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스마트 팜의 재생에너지 자가 소비 촉진을 위한 최적 포트폴리오 분석 A Study of Optimal Power Portfolio to Promote Smart Farms’ Self-consumption of Renewable Energy

https://doi.org/10.5370/KIEE.2022.71.1.001

이상원(Sangwon Lee) ; 조영상(Youngsang Cho)

The purpose of this study is to analyze the ways to expand the supply of renewable energy to large-scale facility farms and to derive policies to promote self-consumption of renewable energy for efficient use and operation of energy nationwide. This is ultimately intended to reduce power consumption for agriculture supplied from fossil fuel power plants. We assume three main technologies such as photovoltaic power generation, energy storage system(ESS), and air heat pump for smart-farm models, and the objective function and conditions for maximizing cost-benefit are analyzed through linear programming. Assuming several scenarios reflecting various conditions of REC price, CO2 emission price, and agricultural electricity rate, which are the benefit factors of operators who installs renewable energy, we present some conditions for promoting self-consumption of renewable energy and emission price levels through simulation. The results of this study can contribute to increase the benefits of smart farm models with renewable energy installed and the efficiency of nationwide power system management.

신재생에너지 보급률 증가에 따른 지역적 태양광 수용 용량 추정에 관한 연구 A Study on Estimating the Local Capacity of Photovoltaic Generation According to the Increase in the Renewable Energy Penetration Level

https://doi.org/10.5370/KIEE.2022.71.1.009

박재민(Jae-Min Park) ; 김인수(Insu Kim)

Due to eco-friendly policies, the use of distributed generation, which is a renewable energy, in the existing power system is increasing. Such renewable energy has advantages of voltage drop compensation and power loss reduction, but has disadvantages such as reverse current phenomenon, overvoltage, and increased complexity. For this reason, research on the effect and stability of the power system when a distributed power supply is connected is becoming important, and it is necessary to calculate the maximum allowable distributed generation supply capacity. To this end, this study analyzed the effect on the transient state when the distributed generation supply is connected to the power system through simulation, and presented the maximum allowable distributed generation capacity by analyzing frequency, rotor angle, convergence time, voltage magnitude, etc. In this study, the IEEE 37-bus test feeder and IEEE 9-bus test feeder were set as the test bed as the simulation system, and the simulation was conducted including the photovoltaic system installation, fault current, and events such as switch opening and closing.

환상형 전력계통에서의 효율적인 조류해석 계산을 위한 전력망 축소 기법 A Power Grid Network Reduction Method in Loop Power Systems for Efficient Power-flow Calculation

https://doi.org/10.5370/KIEE.2022.71.1.023

조해성(Hae-Sung Jo) ; 김인수(Insu Kim)

The purpose of this study is to reduce large-scale power systems to increase the efficiency of power-flow analysis calculation based on fault analysis, thereby improving the stability and reliability of the power system. Case studies demonstrate that it is possible to improve the calculation speed compared to existing power-flow analysis if the reduction of the system is optimized using the newly proposed power grid reduction technique.

C-Vine Copula 기반의 풍력 발전 투입을 위한 확률론적 조류 계산 Probabilistic Load Flow for Assessment of Wind Power Integration Using a C-Vine Copula Function

https://doi.org/10.5370/KIEE.2022.71.1.035

이륜경(Ryungyeong Lee) ; 신훈영(Hunyoung Shin)

Owing to the increase in renewable energy, the power system is exposed to more variability and uncertainty, which increases the difficulty in analyzing the power systems. Thus, an accurate power system analysis considering the stochastic characteristics of renewable energy is required. In this paper, we propose a Monte-Carlo based probabilistic load flow method that takes into account the statistical dependencies between the power generation from the multiple wind sites. To this end, the vine copula method was employed to capture their dependencies and the marginal distribution of the power generation from the multiple wind sites is modeled using a 3-parameter Weibull distribution. In addition, we suggested the chance-constrained optimization problem for properly allocating a target wind power capacity to the buses. From the numerical experiment conducted on the IEEE 39-bus system, it has been demonstrated that the proposed method can more accurately identify the potential risk with the modeling of the dependencies between the power generation from the multiple wind sites as compared to the deterministic approach or probabilistic load flow based on the random sampling method.

5kV급 MV-LVDC 독립형 마이크로그리드의 보호협조 운용방안에 관한 연구 A Study on Operation Method of Protection Coordination in 5kV MV-LVDC Off-grid Micro-grid System

https://doi.org/10.5370/KIEE.2022.71.1.045

김지명(Ji-Myung Kim) ; 이후동(Hu-Dong Lee) ; 한병길(Byeong-Gill Han) ; 노대석(Dae-Seok Rho)

Recently, demands on MVDC distribution system is being significantly increased due to interconnection of renewable energy sources, expansion of DC load and high quality and reliability of the power supply system etc., while commercialization of facilities for MVDC is yet in early stage. Accordingly, demonstration projects on applying existing AC devices and cables to MVDC distribution system are being carried out. However, the protection on high-cost facilities such as converters and cables may not be reliable in the event of fault, and then operation method of protection coordination for MV-LVDC micro grid(MG) system is being required. For the purpose of stable operation of the 5kV MV-LVDC micro-grid, this paper proposes operation methods of protection devices depending on scenarios, such as faults on the MVDC line, LVDC line, or customer load. And also, a modeling of 5kV MV-LVDC MG system, which is composed of PV system, ESS, MVDC cable, DC/DC converter, DC/AC inverter, protection devices etc., is performed using PSCAD/EMTDC S/W. From the simulation results based on the proposed modeling and operation method of protection devices, it is confirmed that this paper is useful tool to perform the proper protection coordination

IEC61850 기반 디지털 변전소의 보호 적정성 평가를 위한 디지털 트윈 개발 Developement of Digital Twin for Protection Adequacy Evaluation of IEC61850 based Digital Substations

https://doi.org/10.5370/KIEE.2022.71.1.055

하광민(Kwang-Min Ha) ; 김수환(Su-Hwan Kim) ; 손규원(Gyu-Won Son) ; 남순열(Soon-Ryul Nam)

Digitalization of substations is universally expanding through digital transformation in existing and new substations. Accordingly, to improve the reliability of operation in digital substations, the requirement is not only expanded for the protection adequacy evaluation on each protection IED but also the constant evaluation of the protection adequacy of the entire digital substation. In general, there is a problem that the state change of the power system is not reflected in protection systems of substations because the protection systems operate without evaluating the protection adequacy of the entire substation after determining the correct value of the protection IEDs. The proposed method in this paper enables the constant evaluation of protection adequacy without additional facilities by applying digital twin technology. In addition, the interoperability of the digital twin model is secured by developing the information exchange between the devices of the digital twin model based on IEC61850.

라인 기동식 릴럭턴스 전동기의 동기화 특성에 관한 연구 Study on the Synchronization Characteristics of Line-Start Synchronous Reluctance Motor

https://doi.org/10.5370/KIEE.2022.71.1.061

김현우(Hyunwoo Kim) ; 박예지(Yeji Park) ; 강준호(Junho Kang) ; 김정원(Jeongwon Kim) ; 정동훈(Dong-Hoon Jung) ; 원성홍(Sung-Hong Won) ; 이주(Ju Lee)

Line-start synchronous reluctance motor(LS-SynRM) has the high efficiency than the induction motor that is almost used in the industrial application. However, LS-SynRM must be operated in the synchronous speed for the high efficiency. When the load has high inertia, LS-SynRM fail to reach the synchronous speed. In this paper, the synchronization characteristics of LS-SynRM are analyzed based on the mathematical model and finite element analysis (FEA). The synchronization characteristics and the synchronous process of LS-SynRM are analyzed based on the mathematical model in s-δ plane. Furthermore, the condition of the synchronization is obtained by the kinetic energy and the motor energy. The three models are selected according to the rotor bar to analyze the synchronization characteristics using FEA. Using the time-harmonic analysis, the equivalent circuit parameters of the three models are calculated, and the starting characteristics and performance of LS-SynRM are compared.

인버터 파라미터에 따른 IPMSM의 공통 모드 전압 및 축 전압 분석 Analysis of Common-mode Voltage and Shaft Voltage of IPMSM Accoring to Inverter Parameters

https://doi.org/10.5370/KIEE.2022.71.1.071

이열경(Yeol-Kyeong Lee) ; 임준혁(Jun-Hyuk Im) ; 허진(Jin Hur)

Cmmon-mode voltage (CMV) occurs in the pulse width modulated (PWM) method inverter of fast switching. The CMV induces shaft voltage and bearing current because of electrical interaction with the parasitic capacitance of the motor. CMV and shaft voltage are considered major causes of bearing fault. Motor fault poses a risk of accidents. Therefore, analysis of the CMV and shaft voltage of the motor is required. This paper analyzes the effect of parameter changes in inverter on CMV and shaft voltage. The parameters include DC link voltage, switching frequency, and carrier wave phase shift. An Equivalent simulation model is constructed through MATLAB/SIMULINK. The parasitic capacitance of the motor is obtained according to its structure. Comparative analysis of CMV, shaft voltage is carried out through simulation. Changes in motor output due to carrier wave phase shift are included. Finally, validation through experiments is included.

커플드 인덕터기반의 계통 연계형 ?uk CCM 인버터의 동적 모델링과 제어기 설계 Dynamic Modeling and Controller Design for Grid-Connected ?uk CCM Inverter with Coupled Inductor

https://doi.org/10.5370/KIEE.2022.71.1.079

김상오(Sang-Oh Kim) ; 한병철(Byeongcheol Han)

This paper presents a dynamic modeling and controller design for a grid?connected ?uk continuous conduction mode (CCM) inverter with a coupled inductor. The primary- and secondary-side inductors of the conventional ?uk converter are integrated into one coupled inductor in the presented ?uk CCM inverter, and it reduces the number of passive components. To make the ?uk CCM inverter with a coupled inductor connected with the grid utility, an output current controller should be designed appropriately. However, the output current control of the presented ?uk inverter is difficult due to the existence of the right-half plane (RHP) zeros in its transfer function. To solve the problem, a dynamic model of the ?uk CCM inverter with a coupled inductor is developed and a repetitive controller (RC) coupled with feedback and feedforward controllers is applied to this inverter. A practical design guideline is also presented to select control parameters. Experimental results using a 200-W prototype demonstrate the acceptable performance of the proposed controller.

IEEE1547-2018 Category3 대응을 위한 연료전지 시스템의 인버터 제어 전략 Inverter Control of Scheme for IEEE1547-2018 Category3 in Fuel Cell Systems

https://doi.org/10.5370/KIEE.2022.71.1.090

원수연(Su-Yeon Won) ; 이교범(Kyo-Beum Lee)

This paper presents an inverter control scheme for fuel cell systems in IEEE1547-2018 Category3. The current configuration of Grid-Connected fuel cell system has limitations Category3’s LVRT (Low Voltage Ride Through) reponse, additional inverter are needed. The inverter operates in an abnormal state where the grid voltage is unstable, and normally supplies the voltage to BOP (Balance of Plant) of the fuel cell system. Simulated verification of the inverter control scheme was performed to change the voltage source to the BOP from grid to inverter during abnormal conditions.

전기차용 BLDC 와이퍼 전동기의 소음 저감을 위한 최적의 도통각 제어 Optimal Conduction Angle Control for Noise Reduction in xEV BLDC Wiper Motors

https://doi.org/10.5370/KIEE.2022.71.1.098

정기헌(Gi-Heon Jeong) ; 오윤기(Yoon-Gi Oh) ; 이교범(Kyo-Beum Lee)

This paper proposes optimal conduction angle for noise reduction in xEV BLDC wiper motors. Fuzzy logic simulation is performed to review the noise influences by conduction angle. After confirming that the current and torque ripple change according to the parameter change, and the optimized control method and parameters from the simulation to the controller is reflected. A test is conducted to reduce noise in a specific frequency range. Noise influences are verified through Fast Fourier Transform analysis on current wave forms and noise test results

Volt-Var 특성 곡선의 기울기가 전압 Oscillation에 미치는 영향 Effect of Volt-Var Characteristic Curve Slope on Voltage Oscillation

https://doi.org/10.5370/KIEE.2022.71.1.105

맹창엽(Chang-Yeop Maeng) ; 조종민(Jong-Min Jo) ; 명노길(No-Gil Myoung) ; 김현진(Hyeon-Jin Kim) ; 조성수(Seong-Soo Cho)

The penetration of Renewable Energy Source (RES) has been increasing because RES is drawing attention by the environmental problem in the worldwide. The power flow can be changed from unidirectional to bidirectional because of increasing the penetration of RES. In bidirectional system, the efficient operation of conventional Voltage Regulators (VRs) is difficult. As one of the various methods to reinforce the conventional VR, the Volt-Var control of the Smart Inverter (SI) is used for supporting the voltage by using the reactive power of RES. This paper verifies the operating principle of the Volt-Var control function of the inverter and the oscillation phenomenon according to the slope of the Volt-Var curve was confirmed through theory, simulation, and demonstration site

n-TOPCon 태양전지의 선택적 에미터 형성 기술 분석 Analysis of Selective Emitter Formation Technology of n-TOPCon Solar Cell

https://doi.org/10.5370/KIEE.2022.71.1.114

정성진(Sungjin Jeong) ; 차예원(Yewon Cha) ; 김성헌(Sungheon Kim) ; 김홍래(Hongrae Kim) ; 박소민(Somin Park) ; 김태용(Taeyong Kim) ; 박진주(Jinjoo Park) ; 주민규(Minkyu Ju) ; 이준신(Junsin Yi)

The main efficiency limiting factors for homogeneous emitter solar cells are resistance loss through metal contact on the front side and recombination loss at the surface. Herein, a selective emitter technology is introduced to solve the above problem, and it is currently commercialized in the mainstream p-PERC (Passivated Emitter Rear Contact) solar cell. The selective emitter boosts efficiency by 0.3~0.4% when compared to a homogeneous emitter, and when applied to the n-TOPCon (Tunnel Oxide Passivated Contact) solar cell, high efficiency of 26% or higher may be predicted. The most widely utilized selective emitter technologies are laser and etch-back. The One-Step Technology, which is suited to the n-TOPCon solar cell process, a laser is suitable for mass manufacturing with high yield. Because selective emitters increase electrical characteristics, which impact cell efficiency, it is required to study and create a technology that is optimal for the n-TOPCon manufacturing process.

DRIE 시스템을 이용한 식각 공정에서 RF 소스 전력과 PR 패턴 사이즈가 깊은 Silicon Via 측벽 표면 형상에 미치는 영향 평가 Effects of RF Power Source and PR Pattern Size on Sidewall Surface of Deep Silicon Via during DRIE Process

https://doi.org/10.5370/KIEE.2022.71.1.121

김동표(Dong-Pyo Kim) ; 김경섭(Kyung-Seob Kim) ; 정중채(Jung-Chae Jeong)

It has been very difficult to etch deep silicon via with photo-resist (PR) during deep reactive ion etching (DRIE) process because of the erosion of PR and the formation of vertical striations. The effects of RF source power and PR pattern size were researched on the etch rate, via top size and etch depth. The PR mask patterns with 10 μm thickness were composed of 10, 20, 30 and 40 μm squares. The etch rates and the etch profiles of deep silicon vias were monitored by the cross sectional FE-SEM images. As the RF source power and PR pattern size were increased, we obtained higher etch rate and deeper etch profiles. However, we observed the vertical striations at the surface of deep silicon vias at higher RF source power.

공진 방사체 임피던스 측정을 이용한 고효율 안테나 회로 설계 연구 A Study of High Efficient Antenna Design Using Impedance Measurements of Radiative Resonators

https://doi.org/10.5370/KIEE.2022.71.1.127

서동호(Dongho Seo) ; 김용주(Yong Joo Kim) ; 윤원상(Won-Sang Yoon) ; 한상민(Sang-Min Han)

A new antenna design method with high efficient characteristics is proposed by measuring input impedance of a radiative resonator. By means of a simple de-embedding method, the resonant frequency and input impedance are measured for antenna resonators. Retaining the resonant antenna characteristics, an impedance-matched feedline can be designed. In order to verify the validation, the patch antenna has been implemented with the proposed method. From the experimental results, the proposed antenna design has presented well matching property, a higher antenna gain, and higher radiation efficiency, compared to a reference patch antenna implemented by a conventional design method.

전방향 모바일 매니퓰레이터의 강인 영상기반 비주얼 서보잉 Robust Image Based Visual Servoing of Omnidirectional Mobile Manipulator

https://doi.org/10.5370/KIEE.2022.71.1.132

조강민(Kangmin Jo) ; 좌동경(Dongkyoung Chwa)

This paper proposes robust image based visual servoing of an omnidirectional mobile manipulator using integral sliding mode control to compensate for the uncertainty that may occur while performing the image-based visual servoing. The stability of the overall omnidirecitonal mobile manipulator system using the proposed method is proven by the Lyapunov stability analysis by showing that the error stays on the sliding surface always and asymptotically converges to zero. In order to solve the singularity problem that can occur when controlling the omnidirectional mobile robot and the manipulator at the same time, a switching technique is proposed in such a way that the omnidirectional mobile robot and manipulator operate sequentially to prevent the abnormal operation of the manipulator and solve the singularity problem. The validity of the proposed robust image based visual servoing method is verified through simulation results.

비선형 마찰 모델을 고려한 BLDC 모터의 적분 슬라이딩 모드 제어 Integral Sliding Mode Control of BLDC Motor considering Nonlinear Friction Model

https://doi.org/10.5370/KIEE.2022.71.1.140

장지영(JiYoung Jang) ; 허준서(Junseo Heo) ; 좌동경(Dongkyoung Chwa)

This paper proposes an integral sliding mode control method for robust control of brushless direct current (BLDC) motor. In order to improve the control performance, the friction force of the motor is expressed using the Stribeck friction model, which is a nonlinear friction model that can accurately represent the friction force at low speed. The parameter values required to design the integral sliding mode controller are then obtained by identifying the parameters of the dynamic equations of the motor including the nonlinear friction model using the Levenberg-Marquardt (LM) algorithm. The performance of the proposed integral sliding mode control method for the BLDC motor is verified through both the simulation results and the actual motor speed control test results.

인공신경망 기반의 적분 슬라이딩 모드 제어기를 이용한 6자유도 매니퓰레이터의 강인 궤적추종 Robust Tracking Control of 6 DOF Manipulator using Artificial Neural Network based Integral Sliding Mode Control

https://doi.org/10.5370/KIEE.2022.71.1.148

황준하(Junha Hwang) ; 좌동경(Dongkyoung Chwa)

This paper proposes a robust tracking control method for a six degree-of-freedom manipulator using artificial neural network based integral sliding mode control. The proposed method is designed to consider all of the actual manipulator's weight, length, and moment of inertia, while maintaining the robustness against the disturbance and the uncertainty of the system model. The trajectory tracking error can be effectively reduced by using the proposed method even in this situation. Both the simulation and experimental results are provided to verify the validity of the proposed method.

쿼드로터 시스템의 강인 추종 제어를 위한 적분 슬라이딩 모드 기반 외란 관측기 및 제어기 설계 Integral Sliding Mode Based Disturbance Observer and Control for Robust Tracking Control of Quadrotor Systems

https://doi.org/10.5370/KIEE.2022.71.1.157

임채윤(Chaiyoon Lim) ; 허준서(Junseo Heo) ; 좌동경(Dongkyoung Chwa)

In this paper, an integral sliding mode disturbance observer (ISMDO)-based integral sliding mode controller (ISMC) design method is proposed for robust tracking control of the position and attitude angles of a quadrotor system with disturbances. First, the dynamics of the quadrotor system is modeled including disturbances. Second, the disturbances are estimated and compensated for by designing the ISMDO. Third, a virtual attitude angle generator is used to control to follow a desired position, and a robust controller is designed to track the desired value of the system. Finally, simulations are performed to verify the proposed control method to show that the proposed robust control method is very effective compared to the methods using only one of the ISMC and the nonlinear disturbance observer.

외란관측기와 모델 예측 제어를 이용한 로봇팔의 하이브리드 위치-힘 제어 Hybrid Position-Force Control of Robot Manipulator via Model Predictive Control Combined with Disturbance Observer

https://doi.org/10.5370/KIEE.2022.71.1.164

이승민(Seungmin Lee) ; 유제휘(Jehwi Yoo) ; 백주훈(Juhoon Back)

When model predictive control is applied to an actual robot, it has a disadvantage of being vulnerable to model error and disturbance. This problem can be solved through robust control using disturbance observer. However, if using robust control to a robot in contact, a the robot apply, is not only hinders, these is a problem. In addition, when using model predictive control with disturbance observer, these is a problem that the model predictive controller can’t reflect system constraints. In this paper, we propose a momentum-based disturbance observer reflecting contact constraint and model predictive controller with disturbance compensation. As different dynamic characteristics in the contact direction, we design a robust controller for each of the contact space and operational space. By combining this with the model prediction control technique, a disturbance observation model prediction controller for hybrid position-force control is derived. The proposed method is validated through simulation.

상태 양자화를 고려한 쿼드로터의 샘플치 퍼지 상태 조정기 설계 Sampled-data Fuzzy State Regulator Design for a Quadrotor Under the State Quantization Consideration

https://doi.org/10.5370/KIEE.2022.71.1.173

한태준(Tae Joon Han) ; 안지호(Ji Ho An) ; 김한솔(Han Sol Kim)

In this paper, a method to design a sampled-data fuzzy regulator is proposed under state quantization. To this end, the attitude and altitude systems of a quadrotor are represented as the Takagi-Sugeno (T-S) fuzzy model. And then, the state regularization condition of each system are derived in the form of the linear matrix inequality (LMI) based on the Lyapunov-Krasovskii functional (LKF). When deriving the condition, we use the robust control technique to handle the uncertainties raised by the state quantization. Finally, the effectiveness of the proposed method is validated through the simulation example.

로봇팔의 시간지연 제어기에서 각 가속도 추정에 대한 추종 성능 비교연구 A Comparative Study of Tracking Performances on Angular Acceleration Estimation for Time-delayed Control of a Robot Manipulator

https://doi.org/10.5370/KIEE.2022.71.1.182

이준우(Joon-Woo Lee) ; 정슬(Seul Jung)

This paper presents a comparative study of tracking performances between several methods of estimating acceleration signals for a time-delayed controller(TDC) of a robot manipulator. To implement the time-delayed controller completely, there are three requirements: 1) Fast sampling time, 2) constant inertia value, and 3) angular acceleration signals. This paper focuses on the acceleration estimation for TDC. Several methods for angular acceleration estimation are tested: 1) Finite difference method with low pass filtering, 2) Kalman filtering, 3) desired angular acceleration, 4) control input, 5) Jacobian relationship. We experimented five methods on one arm of a dual arm robot to follow a circular trajectory and their tracking performances are compared.

DC 모터 속도 제어시스템을 위한 내부모델 원리 기반 제어기와 외란 관측기 기반 제어기의 등가 조건 An Equivalent Condition of IMP-based Controller and DOB-based Controller for a DC Motor Speed Control System

https://doi.org/10.5370/KIEE.2022.71.1.189

손영익(Young Ik Son) ; 양선직(Sun Jick Yang) ; 아마레 네비옐레울 다니엘(Nebiyeleul Daniel Amare)

Asymptotic tracking of a reference model and nonlinear disturbance rejection are two of the most important attributes of an effective control system. A DOB-based controller, which is designed based on an augmented system model including the disturbance dynamics, relies mainly on the disturbance estimation to provide robust reference tracking performance. While IMP-based controller design technique achieves the same result by including a dynamic model of the reference and disturbance in the control system model. However, the similarity of these two control techniques extends beyond basic design consideration. This paper presents an analytical study that reaches an equivalent condition between the two classes of controllers for a DC motor speed control problem. Based on the obtained condition, it is proposed that the DOB-based controller can be designed such that it shows the same performance as the IMP-based controller. This has been further verified through a simulation which shows the same robust performance in both cases.

비선형 자기부상시스템의 저차 외란관측기 제어기 설계에 대한 연구 A Study on a Reduced-Order Disturbance Observer Controller for Nonlinear Electro-magnetic Suspension systems

https://doi.org/10.5370/KIEE.2022.71.1.196

조남훈(Nam-Hoon Jo)

In this paper, we study on a reduced-order disturbance observer (DOB) controller for nonlinear Electro-magnetic suspension (EMS) systems with mass uncertainty. Since it is rather complicated to design a nonlinear DOB controller for nonlinear systems, this paper aims to design a linear DOB controller for nonlinear systems. Since noise suppression of reduced-order DOB controller is superior to that of standard DOB controller, this paper focuses on the reduced-order DOB controller. Using the case study of nonlinear EMS systems, it is found that the followings should be carefully chosen for the design of reduced-order DOB controller: high-frequency gain of the nominal model, pole and zero location of the nominal model, selection of Q-filter, and the choice of primary controller.

기구학 해석을 이용한 바이올린 활 연주 로봇팔의 최소 링크 길이 계산 Minimum Link Lengths Computation of Violin Bow Playing Robot Arm Using Kinematic Analysis

https://doi.org/10.5370/KIEE.2022.71.1.203

최명환(Myoung Hwan Choi)

For a violin playing robot to be successful as an entertainment robot it needs to portray the image of a human arm playing the violin. Hence it is desired that the robotic manipulator has an articulated structure similar to the human arm. Since shorter link lengths result in smaller link weight, smaller actuator size/weight, and thus fast motion capabilities of the manipulator, it is crucial to determine the minimum link lengths of the manipulator. This paper presents a computation method of the minimum link lengths required for the bow motion and the kinematic design of the violin bow playing robot arm. The workspace of the bow playing arm is analyzed using the geometric dimensions of the bow and the violin bridge. The bow frog motion paths are computed for four violin strings. It is shown that a planar RRR mechanism can generate the motion required for violin bow playing robot, and the minimum link lengths of the manipulator are found that result in the robot workspace encompassing the bow frog motion paths and that avoids the singularities in the robot motion path

블록체인 기반의 사용자 관리 가능한 증명서 시스템 A User-manageable Credential System based on Blockchain

https://doi.org/10.5370/KIEE.2022.71.1.210

홍성호(Hyungbo Shim) ; 김희열(Jeong Woo Kim)

Credentials are one of the most important things to prove oneself in modern society. As the world goes digital, credentials change its form from paper to digital. However, digital data are easy to be forged and to be duplicated. To make digital data secure, cryptographic digital signature is the key technology ensuring its authenticity and integrity. And it is an inevitable choice for secure credential management systems. Recently blockchain has been raised as another key technology to guarantee data transparency. It is a decentralized and public ledger of transactions that anyone can participate and execute programs called smart contract. In this paper, we propose a credential management system based on Ethereum blockchain. This system provides users with a means both to manage their credentials by themselves and to prove their credentials without the issuer. We implemented its prototype on Ethereum, and analyzed the proposed system compared to previous systems.

생성 모델을 이용한 전력 수요량 예측 Electricity Consumption Prediction using Generative Models

https://doi.org/10.5370/KIEE.2022.71.1.218

김희상(Heesang Kim) ; 임현승(Hyeonseung Im) ; 문양세(Yang-Sae Moon)

Recently, advanced metering infrastructure (AMI) has been deployed for power demand distribution and energy saving, and correspondingly traditional watt-hour meters installed in apartments and industrial sites are also being replaced with AMIs. Accordingly, power demand prediction using AMIs will become increasingly important to save electrical energy consumption. In this paper, we develop various deep learning-based electricity consumption prediction models using simple neural networks, convolutional neural networks, recurrent neural networks, and encoder-decoder-based generative models. To build prediction models, we use average power demand data collected from various home smart meters. Experimental results show that the generative model outperforms other deep learning-based models in terms of mean squared error, and we roughly explain why the generative model is better than other models by examining the activation layer output distributions.

XAI 알고리즘을 통한 전동기 고장 진단에서의 연속 웨이블릿 변환 데이터 성능 평가 Performance Evaluation of the Continuos Wavelt Transformation Data in Motor Fault Diagnosis through XAI Algorithm

https://doi.org/10.5370/KIEE.2022.71.1.225

한지훈(Ji-Hoon Han) ; 박상욱(Sang-Uk Park) ; 홍선기(Sun-Ki Hong)

The data mainly used for motor fault diagnosis is FFT. However, preprocessing such as continuous discrete wavelet transform is used. When using deep learning algorithms, the performance of the data is evaluated by the model output. However, in order to improve the learning possibilities and preprocessing performance of data, performance evaluation from a model perspective is required. For this purpose, data performance evaluation using the LRP algorithm, one of the XAI techniques, is studied. Initial fault state diagnosis using current data, which is difficult to solve with FFT data, is performed with STFT and CWT data, and performance is evaluated through LRP. Experimental Results STFT and CWT are preprocessing techniques that enable the use of current signals for early fault diagnosis. Among the two preprocessing methods, the use of CWT is more preferable because the flexibility of the preprocessing is increased.

모바일 게임플레이 행동 정책 학습을 위한 YOLOv3 기반 강화학습 YOLOv3 based Reinforcement learning for mobile game playing policy

https://doi.org/10.5370/KIEE.2022.71.1.233

이태학(Taehak Lee) ; 조영완(Youngwan Cho)

This paper proposes a reinforcement learning model that constructs a sequential behavioral decision policy for playing a game by extracting feature points in an environment in which a game image is given. In this paper, we propose a method of optimizing performance through state domain reduction, transfer learning, and multi-agent-based modeling to obtain the maximum score available for game environments that must continue their actions and have time limitations in decision making. These methods were implemented for the ‘Timberman’ game environment and experimented with learning performance by applying them as a player’s behavioral policy to evaluate the trained model.

YOLOv4-CSP 기반 실신 감시 시스템 Swoon Monitoring System based on YOLOv4-CSP Object Detection Algorithm

https://doi.org/10.5370/KIEE.2022.71.1.239

채정우(Jung-woo Chae) ; 김태경(Tae-kyeong Kim) ; 조현종(Hyun-chong Cho)

When swoon occurs, it is important to detect it immediately. If immediate and quick detection is not possible, additional serious accidents may occur. Therefore, this study proposed swoon monitoring system that can detect swoon from real-time images of CCTV based on the increasing number and installation of CCTV. For the detection of swoon, deep learning based object detection algorithm applied with the Cross Stage Partial connections network model was used. Through this, swoon detection is performed within a single frame, and the amount of computation required for swoon detection is reduced and can have a fast processing speed. In addition, it is possible to have high detection performance through various BoF and BoS techniques with CSP network model. The result of swoon detection and classification performance through object detection algorithm showed 94.2% F1-Score, 92.6% mAP and 95.4% Accuracy

탑뷰 이미지를 사용한 영상기반 한우 체중 추정 시스템 Image-based Korean Cattle Weight Estimation System using Top View Image

https://doi.org/10.5370/KIEE.2022.71.1.246

이창복(Chang-bok Lee) ; 박연수(Yeon-Soo Park) ; 조현종(Hyun-chong Cho)

Weight information is important to understand the growth of cattle and to calculate an appropriate daily feed amount. However, since the method of measuring weight using a scale consumes a lot of labor and time, weight information is not actively used in Korean cattle farms. Image-based weight estimation can be a new weight estimation method that does not cause stress to cattle and does not require labor. In this study, top-view data that is easy to apply to actual Korean cattle farms was used. A segmentation mask was obtained by dividing the cow and the background, and weight was estimated by extracting weight correlation factors from the segmentation mask. The weight estimation of the method of proposing area, body length, and body width, which are verified factors based on related studies, reached an error rate of 8.5%, and when the extracted grid elements were added to improve performance, it reached 7.5%.

금속 음영이 포함된 CBCT 영상에서 딥러닝을 이용한 해부학적 구조물의 다중 클래스 분할 방법 Multi-class Segmentation of Anatomical Structures Using Deep Learning in CBCT Images Containing Metal Artifacts

https://doi.org/10.5370/KIEE.2022.71.1.253

양수(Su Yang) ; 천소영(Soyoung Chun) ; 김다엘(Dael Kim) ; 전보성(Bo Soung Jeoun) ; 유지용(Jiyong Yoo) ; 강세룡(Se-Ryong Kang) ; 최민혁(Min-Hyuk Choi) ; 김조은(Jo-Eun Kim) ; 허경회(Kyung-Hoe Huh ?) ; 이삼선(Sam-Sun Lee) ; 허민석(Min-Suk Heo) ; 이원진(Won-Jin Yi)

In order to perform preoperative surgical planning, accurate segmentation of anatomical structures in cone-beam computed tomography (CBCT) images is required. However, this image segmentation is often impeded by metal artifacts, and it takes a lot of time due to morphological variability in patients. In this paper, we proposed a deep learning based automatic multi-calss segmentation method for anatomical structures in CBCT images containing metal artifacts. Four U-Net based deep learning models were used for anatomical structure segmentation. Each deep learning model was constructed by changing the encoder of U-Net architecture to the backbones (DenseNet121, VGGNet16, ResNet101, and EfficienNetB4). For training and testing our method, we used 20744 CBCT images containing metal artifacts from 30 patient datasets. Experimental results show that the segmentation performances of the mandible, midfacial bone, mandibular canal, and maxillary sinus were achieved F1 scores of , , , and using DenseNet121 with Tversky loss, respectively. Furthermore, our method was able to perform robust and accurate segmentation of anatomical structures in CBCT images containing metal artifacts.

확률적 정보량에 의한 표면근전도 진폭 추정 매개변수 평가 Evaluation of SEMG Amplitude Estimation Parameters by Amount of Probabilistic Information

https://doi.org/10.5370/KIEE.2022.71.1.261

이진(Jin Lee)

Optimal Amplitude estimation from the SEMG(surface electromyogram) signal is important because it can be used potential sources to control prosthetics and robotics. In this paper, four representative SEMG amplitude estimation parameters(ARV:average rectified value, RMS:root mean square, MTA:mean turn amplitude, MSA:mean spike amplitude) were evaluated based on probabilistic information theory, which determine the amount of information that each parameter is able to extract from SEMG signal. Surface EMG signals from eleven subjects were recorded in biceps brachii muscle with constant isometric 20, 50, and 80%MVC contractions. The parameters were investigated by the amount of mutual information between stimulus(contraction level) and response(amplitude estimation parameter) variables. Results of this study show there are no statistical significant differences(p<0.05) in the point of amount of information among the four variables. Although the evaluation method suggested here were applied to amplitude estimation parameters, it can also be considered as alternative tool to evaluate various processing technique in different areas of surface EMG analysis.

가스절연지상개폐기 PD 자동진단기법 연구 A Study on the Automatic PD Diagnosis Method for Gas Insulated Load Break Switches

https://doi.org/10.5370/KIEE.2022.71.1.267

전시식(Si-Shik Jeon) ; 차동욱(Dong-wook Cha) ; 김영달(Young-Dal Kim)

Partial discharge diagnosis is being carried out to prevent failure of ground switch of distribution facilities. However, the reliability of partial discharge diagnosis is insufficient because the results are different depending on how the experts classify the partial discharge and noise signals. Therefore, in this paper, a method to automatically classify partial discharge and noise signals was studied in order to improve the reliability of the partial discharge diagnosis results of ground switch. Partial discharge and noise signal are obtained through the High Frequency Current Transformer(HFCT). And the features were extracted based on the pulse shape analysis, the standard deviation and gravity center of signal. The features are used as input to neural networks and learned using back-propagation. In addition, the structure of neural networks was optimized through genetic algorithm.

자가용 전기설비의 변압기 검사 통계 기반 교체 주기 분석 Analysis of Replacement Cycle based on Inspection Statistics of Receiving Power Transformer for Private Electrical Facilities

https://doi.org/10.5370/KIEE.2022.71.1.275

김영석(Young-Seok Kim) ; 김종민(Chong-Min Kim) ; 정기석(Ki-Seok Jeong)

This study was conducted a reliability analysis of the replacement cycle based on the inspection data of receiving power transformers in domestic private electrical facilities. The dataset was constructed with a sample of 529,024 transformer data from about 2.4 hundred-thousands high voltage electrical consumers. Five examples were selected for cumulative failure probability and failure rate based life indicators. Considering the over or under estimation of reliability analysis, the appropriate data sampling level was selected by examining the correlation with life indicators according to the failure data rate. Two-parameter weibull probability distribution was selected by based on the data distribution pattern and distribution suitability review results based on AndersonDarling statistics. Finally, the replacement cycle was presented as a cumulative failure probability-based B10, B20, and mean failure to time and failure rate-based life indicator.