Mobile QR Code QR CODE : The Transactions of the Korean Institute of Electrical Engineers

실계통에서 유도전동기 적용 MVR의 기동속도 변화에 따른 전압 전류 특성 분석 Analysis of Voltage and Current Characteristics According to the Change of Starting Speed of MVR Applied with Induction Motor in Practical System

https://doi.org/10.5370/KIEE.2020.69.11.1579

임태문(Tae-Moon Lim) ; 이희진(Hee-Jin Lee)

When starting a large-capacity induction motor, a very large inrush current is generated, causing a voltage drop in the system. If this voltage drop is large, it affects the other loads and makes it impossible to operate. Also, if the load torque applied to the induction motor is greater than the motor torque, the motor may fail to start. When selecting a motor that drives a large-capacity rotating machine, a starting method and starting time suitable for the power capacity and load characteristics are required. It is a condolfer starting method of a large-capacity induction motor that is actually applied in the industrial field, and it analyzes the operating characteristics that appeared during trial operation, so that it can be used when operating a large-capacity motor.

AC-DC 복합 전력계통 해석을 위한 대규모 전력계통 실시간 모의 기술 개발 Development of Full-Scale Power System Real-time Simulation Technology for AC-DC Integrated Power System Analysis

https://doi.org/10.5370/KIEE.2020.69.11.1586

오승찬(Seung-Chan Oh) ; 송지영(Ji-Young Song) ; 이재걸(Jae-gul Lee) ; 정솔영(Sol-young Jung) ; 구현근(Hyunkeun-Ku) ; 신정훈(Jeong-hoon Shin)

In the case of the KEPCO power system, the installation of power electronic devices such as FACTS/HVDC is increasing to maximize the power transmission capability. The installation of these power electronic devices increase the utilization of the conventional transmission facilities. However, it can also cause power system instability due to the control instability and interaction between conventional facilities and other power electronic devices. By these reasons, the importance of the AC-DC integrated power system analysis technology is increasing. This technology provide the capability to analysis interaction among conventional ac facilities and power electronic based devices. In this paper, AC-DC integrated power system analysis technology based on the real-time simulation. As a case study, the result of the dynamic performance tests of the facilities that operating on the KEPCO power system are provided.

BESS를 이용한 대규모 발전단지 제약완화 효과에 관한 연구 A Study on the Mitigation of Constraints of Large Scale Power Plant using BESS

https://doi.org/10.5370/KIEE.2020.69.11.1597

정솔영(Sol-young Jung) ; 오승찬(Seung-Chan Oh) ; 송지영(Ji-Young Song) ; 구현근(Hyunkeun-Ku) ; 신정훈(Jeong-hoon Shin) ; 이재걸(Jae-gul Lee)

In case of 765kV transmission line tripping, there is a Special Protection Sheme(SPS) in Korea power system. To avoid generator over-speed, preselected generators can be tripped by SPS. However, the system frequency can be under the Under Frequency Relay(UFR) 1st pickup level 59.92Hz when large scale generators are tripped. Accordingly, generation constraints can arise until new transmission lines are installed. In this paper, we proposed BESS for mitigating generation constraints of large scale generators, and we applied to the Korean power system in 2022 to analyze the effects of BESS application.

신규 열병합 발전 플랜트 전력계통 안정화장치(PSS)의 실계통 파라메터 튜닝 연구 Study on the tuning of Power System Stabilizers(PSSs) in the newly installed Combined Heat and Power Plant(CHP)

https://doi.org/10.5370/KIEE.2020.69.11.1604

신정훈(Jeonghoon Shin) ; 정솔영(Solyoung Jung) ; 구현근(Hyunkeun Ku) ; 오승찬(Seungchan Oh) ; 송지영(Jiyoung Song) ; 김수배(Soobae Kim) ; 이재걸(Jaegul Lee)

Due to the global environmental issue to reduce carbon dioxide emission, combined heat and power (CHP) plants have widely been installed adjacent to load pockets. This kind of CHP plant typically consists of a gas and a steam turbine. Because of inherent complicated structures for the combined power plant, the application of power system stabilizers (PSSs) is not easy. Because it is important to set the parameters of PSSs installed in both sides without any negative impact. Careful consideration of possible interaction with the stabilizers installed in Gas Turbine Generator (GTG) and Steam Turbine Generator (STG) should be needed. In the paper, the whole procedure of PSSs tuning for the newly constructed CHP plant(569MVA) is proposed starting from data setup for tuning the parameters based on raw data provided by manufacturers to field test for performance verification of tuned PSSs

저 차원 Hankel 구조를 이용한 PMU 데이터 복구에 관한 연구 Study on Missing PMU Data Recovery by Exploiting Low- Dimensional Hankel Structures-Experiments with KEPCO PMU Data Set

https://doi.org/10.5370/KIEE.2020.69.11.1616

신정훈(Jeonghoon Shin) ; 남수철(Suchul Nam) ; (Evangelous Farantatos) ; (Meng Wang) ; 성태응(Tae-Eung Sung)

Phasor Measurement Units (PMUs) provide synchronized phasor measurements at much higher sampling rate than that in the traditional Supervisory Control And Data Acquisition (SCADA) system. Several synchrophasor-based algorithms and techniques have been and continue to be developed for real-time operation applications such as state estimation, stability analysis, disturbance detection, dynamic security assessment etc. However, synchrophasor data quality limits the incorporation of synchrophasor-based applications into control room operations environment and processes. The goal of this project is to develop methods that can improve synchrophasor data quality by recovering missing data reliably and efficiently. Data recovery refers to methods that estimate the values of missing data in the synchrophasor streams. Recently, modeless missing data recovery methods have been developed, that exploit the low-rank property of the spatial-temporal synchrophasor data blocks. A spatial-temporal synchrophasor data block can be considered as a matrix that is constructed by the measurements sampled at consecutive time instants with each row denoting the measurement of one certain channel across time. By exploiting the low-rank property of synchrophasor data matrices, the missing data recovery can be formulated as a low-rank matrix completion problem. The low-rank matrix completion problem has been extensively studied in the past few years and several algorithms have been developed to recover a low-rank matrix from partial observations. In this study, synchrophasor data analysis has been combined with low-rank matrix completion theory to develop a missing synchrophasor data recovery technique and tool.

RTDS 기반의 시각동기 위상측정데이터를 이용한 실시간 전압안정도 감시 및 선로정수 추정 Real-time voltage stability monitoring and transmission parameter estimation based on phasor measurement data using real-time digital simulator

https://doi.org/10.5370/KIEE.2020.69.11.1626

고백경(Baekkyeong Ko) ; 남수철(Suchul Nam) ; 구본길(Bongil Koo) ; 강성범(Sungbum Kang) ; 신정훈(Jeonghoon Shin)

Korea electric power system has more than 40% of load demand concentrated in the metropolitan area. Therefore, most of the power generation is supplied to the metropolitan area using 765kV and 345kV transmission lines. The main lines are 2 routes of 765kV and 4 routes of 345kV between the metropolitan area and the non-metropolitan area, these lines are called interface lines. KEPCO developed WAVI and IF indices, which can be monitoring the voltage stability in real time using PMU data. And KEPCO also developed a transmission lines parameter estimation algorithm by using PMU data for protection relay setting. In this paper, we will describe the verification results based on large-scale RTDS to verify the two algorithms developed above. And the algorithm results are connected SIGUARD PDP Server which is a commercial PMU data concentrator. We are also planning to connect the algorithms to real operating WAMS system in future

디지털변전소 상호운용성 검증시스템 개발 The Development of Verification System for Interoperability in Digital Substation

https://doi.org/10.5370/KIEE.2020.69.11.1633

박유영(Yu-Yeong Park) ; 이남호(Nam-Ho Lee) ; 김남대(Nam-Dae Kim) ; 김우중(Woo-Joong Kim) ; 신정훈(Jeonghoon Shin)

Since KEPCO’s digital substation is not composed of a single manufacturer’s device, but consists of 4 to 6 different manufacturers’ devices, interoperability between devices is considered very important. IEC 61850 International Standard does not define a single way of expressing all information that intelligent electronic devices in substations must implement, but allows the freedom to implement it differently for each manufacturer. The reality is that the operating environment for S/W implementation, communication library, operation method for system operation, and response method for communication failures differ from manufacturer to manufacturer. For this reason, compatibility problems between devices occurred from the beginning of the introduction of digital substations and caused obstacles in substation operation. In this paper, by analysing various compatibility problems that occurred at the site, it explains digital substation interoperability test-bed that can select interoperability issues rather than simply device failures and execute test procedures to verify them in advance, and the verification system that can automatically carry out the whole test process.

PMU 정보를 활용한 전력계통 상황인지 기술 개발 Development of Power System Situation Recognition Technology Using PMU Data

https://doi.org/10.5370/KIEE.2020.69.11.1640

남수철(Suchul Nam) ; 고백경(Baekkyeong Ko) ; 구본길(Bongil Koo) ; 강성범(Sungbum Kang) ; 신정훈(Jeonghoon Shin)

The PMU can collect time synchronized and very accurate monitoring data. Recently, this technology has received a lot of attention to improve the stability of the power system. The PMU provides fast and accurate monitoring information to the operator, helping the operator to make the best choice. For this reason, many countries are adopting PMU technology. Korea has also attempted to introduce PMU technology, but the introduction has been delayed for various reasons. As the use of PMUs is delayed, concerns about operational difficulties due to renewable energy are increasing in the field. To solve these problems, KEPCO conducted research on expanding the introduction of PMU technology from 2017, and completed it in June 2020. Through the successful implementation of this research project and application to the field, KEPCO has played an important role in changing the negative perception of PMU by domestic engineers. This paper introduces the efforts of KEPCO and plans to expand the use of PMUs in Korea in the future

사후 고장분석에 기초한 송전케이블 선로정수 산정기준의 개선 Improvement of guideline for calculating line constants based on post-fault analysis of cable transmission lines

https://doi.org/10.5370/KIEE.2020.69.11.1649

최종기(Jong-kee Choi) ; 이유진(Yu-jin Lee) ; 이상영(Sang-young Lee) ; 김형근(Hyeong-geun Kim) ; 신정훈(Jeong-hoon Shin)

The symmetrical impedances of a transmission line are important parameters for both accurate fault calculation and reliable protective relay setting. While overhead line impedance calculation results generally agree well with measured impedances at reasonable accuracy, underground transmission line impedances do not agree well very often. So there has been an urgent need for better guideline to determine which impedance should be used among measured and calculated cable transmission line impedances. In this paper, various post-fault analysis of 154kV cable transmission lines were conducted to improve the current KEPCO guideline based on sound technical background as possible.

전력손실 최소화를 위한 심층 강화학습 기반 배전계통 재구성 Distribution Network Reconfiguration to Minimize Power Loss Using Deep Reinforcement Learning

https://doi.org/10.5370/KIEE.2020.69.11.1659

임세헌(Se-Heon Lim) ; 김태근(Tae-Geun Kim) ; 윤성국(Sung-Guk Yoon)

Distribution network reconfiguration (DNR) is a technique that changes the status of sectionalizing and tie switches for various purposes such as loss minimization, voltage profile improvement, load leveling, and hosting capacity increase. Although previous algorithms for DNR show good performance, they still have practical limitations. Most of the algorithms assumed that a central coordinator knows all parameters and/or perfect states in a distribution network. Reinforcement learning which is a model-free optimization technique can be a key way to overcome these limitations. This work proposes a DNR scheme using deep reinforcement learning to minimize power loss defined by the amount of line loss and renewable energy curtailment. We model the DNR problem as a Markov decision process (MDP) problem and apply the reinforcement learning algorithm to solve this problem in real-time. Simulation result using 33-bus radial distribution system shows that the proposed scheme shows similar performance compared to an existing method which uses all information on the distribution network

170kV 가스절연개폐기용 차단 접점 마모에 따른 기계적 열화 특성 분석 The Effect of Mechanical Wear on the Contact applied to 170kV Gas Insulated Switchgear(GIS)

https://doi.org/10.5370/KIEE.2020.69.11.1668

한기선(Ki-Sun Han) ; 이종건(Jong-Geon Lee) ; 주형준(Hyung-Jun Ju) ; 강지원(Ji-Won Kang)

This paper deals with the effect of mechanical wear on the contact of circuit breaker applied to the 170kV Gas Insulated Switchgear (GIS). The arc occurrence was ignored to verify the pure effect of mechanical wear on the contact of circuit breaker. Since only the effect of the mechanical wear was considered, the experiment was carried out under no-load state. The accelerated test method was adopted and the specimens were operated until the lifetime same as actual 170kV GIS contact. The specimens were tripped and closed up to 20,000 times and the its electrical resistances and weights were measured at regular intervals. Based on the test results, the correlation between mechanical wear of contact and trip/close coil current was analyzed. The analysis result showed that, even the slight mechanical wear of contact can cause delays in the trop/close operation of the GIS.

태양광 발전기의 계통 접속 허용용량 증대를 위한 배전사업자 관점의 경제성 평가 An Economic Evaluation of the Viewpoint of Distribution System Owner for the Increase of Hosting Capacity in the Distribution System with Interconnected Solar Photovoltaic Generators

https://doi.org/10.5370/KIEE.2020.69.11.1675

우수화(Su-Hwa Woo) ; 권보성(Bo-Sung Kwon) ; 배동진(Dong-Jin Bae) ; 문찬호(Chan-Ho Moon) ; 송경빈(Kyung-Bin Song)

Economic evaluation is performed to calculate the hosting capacity of solar PV generator that is economically feasible from the perspective of the distribution system owner. The benefit for the increase of hosting capacity in the distribution system is avoided investment cost such as the construction cost of distribution line, the maintenance cost of distribution line, and the replacement cost of distribution facilities. The cost is the investment cost of the smart inverter for increased hosting capacity. The sensitivity analysis on the disposal cost of the smart inverter, the maintenance cost of distribution line, and the length of distribution line is performed to compensate for the uncertainty of future cost.

태양광 발전시스템의 손실비용 절감을 위한 실 데이터 기반 고장진단 프로그램 개발 Development of Fault Diagnosis Program for reducing Power Loss Cost of the Photovoltaic Power System using Actual Operation Data

https://doi.org/10.5370/KIEE.2020.69.11.1682

조경희(Kyeong-Hee Cho) ; 김응상(Eung-Sang Kim) ; 이동규(Dong-Kyu Lee) ; 이문수(Munsu Lee) ; 박준호(June Ho Park)

Countries are looking for a pathway toward a sustainable transition from fossil-based to less or zero-carbon sources in energy sector in order to reduce its impact from climate change. Among different renewable resources, photovoltaic power system (PV) is considered as one of the most promising technology, which has the biggest potential for increasing renewable energy. However, its profit can be varied depending on operation and management, which possibly causes performance degradation and safety issues due to faults. Therefore, we have collected actual operation data from the PV monitoring system which located in Changwon, Gyeong-nam province during one year. While most of the PV system has security function which is limited to its inverter protection, in this study, based on fault data software program is developed for fault diagnosis in order to increase robustness of the PV system and minimize operation cost. Also, the program comprises machine learning algorithm based on fault data to classify its types of faults. It also presents economic loss of each PV module considering mean time to repair (MTTR) occurred from the event of faults in the PV system. As a result, the program helps faster fault diagnosis of the PV system and decreasing overall operation cost for the system operator.

디지털변전소 트러블 모의장치 개발에 관한 연구 A Study on the Development of Trouble Simulator for Digital Substation

https://doi.org/10.5370/KIEE.2020.69.11.1689

박유영(Yu-Yeong Park) ; 김석곤(Seok-Kon Kim) ; 박철원(Chul-Won Park)

As of January 2020, KEPCO has operated about 60 digital substations. Digital substation has established for new 154kV substations since 2013, and it has installed as a multi-vendor-based system in which 4 to 6 manufacturers' devices are selected from among 30 various manufacturers. It was initially determined that there would be no interoperability problems when using electronic devices that satisfy IEC 61850 international standard, but there have been large and small obstacles in digital substations from initial operation until now. The main reason for this was that, except for device failure, communication messages were interpreted in information exchange between facilities, and when a failure occurred, the response and interpretation method was different for each manufacturer. IEC 61850 international standard is not defined to use all expression methods in the same way. Within a certain range, IEC 61850 has the range that manufacturers can freely be implemented, and the continuous change in the operating condition and software affects the interoperability of digital substation. Trouble simulator is a device to test the performance of conventional and new devices in digital substation by reproducing the field failures occurring in the digital substation. In addition, it is possible to prepare countermeasures and secure interoperability of digital substation system by simulating and testing possible obstacles in advance. In this paper, it will be discussed the configuration of the developed trouble simulator for failure testing of digital substations and actual application cases

저압배전선로 전압안정화를 위한 상태관측과 반복제어를 적용한 무효전력 보상기 Reactive Power Compensator with State Observer and Repetitive Control for Stabilization of Low Voltage Distribution Line

https://doi.org/10.5370/KIEE.2020.69.11.1697

서정진(Joungjin Seo) ; 김영록(Youngroc Kim) ; 차한주(Hanju Ch)

In this paper, a new reactive power control algorithm using a stat observer and repetitive control for voltage adjustment to the low-voltage distribution line is proposed and verified by simulation and experiment. A reactive power compensator has a single -phase full bridge inverter structure and consists of DC voltage controller to maintain a constant DC voltage, and current controller for reactive power generation. A DC ripple compensation method use an output from the state observer and the output is used as the DC voltage controller feedback to regulate the DC voltage constant. In order to inject a stable reactive power, the fundamental component of current is controlled by a PI controller, and a repetitive controller is connected in parallel with the PI controller to compensate for lower-order harmonics. The repetitive controller, as implemented in the synchronous coordinate system, serves to eliminate low-order odd harmonic components. The proposed control technique is experimented with a ±5kVar single phase inverter system and verified the performance of the proposed algorithm by confirming that THD is reduced to 2% from 9%.

머신 러닝 방법을 이용한 절연 게이트 쌍극자 트랜지스터의 도핑 농도 최적화 및 영향도 분석 Optimization and Analysis of Doping Concentration in Insulated-Gate Bipolar Transistor using Machine-Learning Method

https://doi.org/10.5370/KIEE.2020.69.11.1703

김정식(Jungsik Kim)

In this study, machine-learning and technology computer-aided design (TCAD) simulation are collaborated for optimizing and analyzing the doping concentration in insulated gate bipolar transistor (IGBT). Stochastic current-voltage data is extracted from TCAD simulation. Theses results are trained in XGBoost algorithms of machine-learing method. From the trained results, targeting the performance of IGBT without additional experiment or numerical simulation is being easy and fast. Therefore, the collaboration of TCAD simulation and machine-learning is effective and useful to save time and cost in the development of semiconductor.

Black-box 아크 모델의 비선형 특성을 활용한 고체 절연물 내 보이드에 의한 부분방전 해석모델 개발 Development of Partial Discharge Analysis Model by Void in Solid Insulation Using Nonlinear Characteristics of Black-box Arc Model

https://doi.org/10.5370/KIEE.2020.69.11.1707

주형준(Hyung-Jun Ju) ; 이종건(Jong-Geon Lee) ; 한기선(Ki-Sun Han) ; 박규훈(Kyu-Hoon Park) ; 이방욱(Bang-Wook Lee)

Partial discharge measurement and analysis of solid insulators should be performed indispensably for predicting the insulation life and diagnosis of electric power facilities. Prior to the actual partial discharge measurement, the partial discharge can be analyzed through a simulation study based on the design of an accurate equivalent model of the insulating materials. The high reliability of partial discharge simulation can reduce cost, manpower, and time required when performing actual partial discharge measurement tests, and can be effectively applied to complex partial discharge characteristics analysis of insulating materials. In this paper, a partial discharge simulation was performed by designing an equivalent model of a partial discharge test cell injected with a small circular void in the inner center. To evaluate the reliability of the simulation results, the actual partial discharge of the test cell was measured according to the test procedure of IEC-60270. A capacitive equivalent model that can simulate the partial discharge characteristics of the test cell was designed and a simulation study of partial discharge inside the insulator was conducted. The partial discharge measurement system is designed using a black-box arc model that can describe the nonlinear characteristics of the arc. The parameters of the simulation model were selected by establishing a simulation scenario assuming the condition of adding electrical deterioration to the voids of the same size. In addition, to verify the simulation results, PRPD (Phase Resolved Partial Discharge) patterns generated in voids was obtained using a partial discharge measuring device. The parameters related to the partial discharge characteristics such as the maximum partial discharge amplitude, number and distribution were investigated. As a result, the consistency of the partial discharge simulation results was verified through a comparative study of simulation and test results, and a reliable partial discharge modeling technique was established.

K-EDES: 국내 변전소 지진 피해예측 웹시스템 K-EDES: Earthquake Damage Estimation Web-System for Electrical Substations in South Korea

https://doi.org/10.5370/KIEE.2020.69.11.1717

황명하(Myeong-Ha Hwang) ; 이인태(In-Tae Lee) ; 연관희(Kwan-Hee Yun)

Recently, various research and developments related to the large-scale earthquake source generation model and facility damage estimation model have been conducted. However, the earthquake damage estimation model and visualization research for electrical substations in South Korea are insufficient. Therefore, we propose K-EDES which includes an earthquake source generation model considering topography characteristics and damage estimation for electrical substations in South Korea. K-EDES consists of large-scale seismic source synthesis, damage estimation model for electrical substations, model simulator, visualization of damage estimation results, and provides an environment for integrated management. In addition, K-EDES can be performed in real-time because it includes distributed parallel systems and resource management functions for resource status and work schedule management. The results of this study helps real-time response of electrical substations management in the event of an actual earthquake. Therefore, it is possible to shorten the period of earthquake damage recovery and reduce the repair and maintenance costs.

QoS 기반 웹서비스 컴포지션을 위한 효율적인 리플래닝 기법 Efficient Replanning Technique for QoS-aware Web Service Composition

https://doi.org/10.5370/KIEE.2020.69.11.1724

길현영(Hyunyoung Kil) ; 남원홍(Wonhong Nam)

A Web service is a service provided by software systems to support machine to machine inter-operations over Web. Given a set of Web services and a goal, the QoS-aware Web service composition problem constructs a composite Web service with the optimal accumulated QoS value, which satisfies the given goal specification. However, in the real world environment, frequent changes happen inherently ― for instance, temporary machine down, heavy system workload, and network failure. If the solution we have constructed is not valid anymore due to the changes, we have to solve a new problem again. Ordinary approaches to find a new solution from scratch may waste computation time, since they explore the whole searching space again. Hence, in this paper, we propose a novel replanning algorithm, which does not solve the new composition problem from scratch but explores only the changed space to identify the new optimal solution. In the experiment, our replanning algorithm can deal with the composition problem much faster than the original algorithm to solve from scratch.

딥 러닝 알고리즘을 이용한 전동기 고장 진단에서의 알고리즘 성능 향상 기법 연구 A Study on the GAN Algorithm Performance Improvement Method in Motor Failure Diagnosis Using Deep Learning Algorithm

https://doi.org/10.5370/KIEE.2020.69.11.1732

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

When deep learning is applied to motor fault diagnosis, the Generative Adversarial Network (GAN) algorithm is used to compensate for the insufficient number of data. However, the model’s performance includes not only classification performance, but also overfitting degree and outlier detection performance. Unlike classification performance, outlier detection performance is affected not only by the amount of data but also by the quality. However, increasing similar data is not the best way to increase the model’s overall performance. Therefore, an RMSE-based data evaluation technique is proposed to find virtual data that maximizes model performance. It was confirmed that the proposed method helps to improve the outlier data detection performance of the model.

시뮬레이티드 자율주행 자동차의 주행행동 학습을 위한 기반 강화학습 CNN based Reinforcement Learning for Driving Behavior of Simulated Self-Driving Car

https://doi.org/10.5370/KIEE.2020.69.11.1740

조영완(Youngwan Cho) ; 이종석(Jongseok Lee) ; 이광엽(Kwangyup Lee)

This paper proposes a self-learning method for autonomous vehicle driving behavior using reinforcement learning without considering the dynamic model of the vehicle. In order to make decision needed for determine the optimal driving behavior (steering, throttle, brake) to achieve a given driving purpose in each state by using state information of the vehicle, such as vehicle movement speed, direction, degree of deviation from the center of the track, and distance to the edge of the track, we propose a method of applying the reinforcement learning by the DDPG structure and further using the driving image to improve driving performance. In this paper, we propose structures of an action decision network(Actor) and an action value evaluation network(Critic) to implement the DDPG learning model. We also propose a prediction model for predict the next state driving image based on the current driving image to improve driving performance in the corner path and a corner classifier for classifying the driving track type. The method proposed in this paper was implemented in a TORCS simulator environment, and the performance of the target driving behavior was evaluated through applying the learning model to driving agent.

딥러닝을 위한 하이브리드 가지치기 Hybrid Pruning of Deep Learning System

https://doi.org/10.5370/KIEE.2020.69.11.1750

이성준(Sungjun Lee) ; 서기성(Kisung Seo)

A convolutional neural network (CNN), which is one of the deep learning models, has been very successful in a variety of computer vision tasks. Filters of a CNN are automatically generated, however, they can be further optimized since there exist the possibility of existing redundant and less important features. Evolutionary algorithms is adopted to remove the unnecessary filters in order to minimize the parameters of CNN networks while maintaining a good performance of classification. Previous approach using evolutionary algorithm shows excellent performance for the filter reduction, but has a limitation of huge amount of computation. Hybrid approach combining evolutionary algorithm and weight based pruning (APoZ) is proposed to enhance the efficiency of reduction and to reduce computation complexity. We demonstrate the proposed filter reduction method performing experiments on CIFAR-10 data based on the classification performance.

HEVC VLSI 디블로킹 필터를 위한 메모리 할당 기반의 설계 Memory Allocation-based VLSI Design for HEVC Deblocking Filter

https://doi.org/10.5370/KIEE.2020.69.11.1755

김현준(Hyunjun Kim) ; 배종우(Jongwoo Bae)

In this paper, we propose a high-performance VLSI architecture and memory allocation algorithm for HEVC Deblocking Filter. For high-performance VLSI design, a parallel architecture is employed. Our architecture employs 8 parallel filters and 4-stage pipeline to meet the high-performance video requirements. In the implementation of highly parallel VLSI architecture, high bandwidth and low latency memory access is very important. A novel memory allocation algorithm is proposed to reduce the on-chip SRAM access conflicts between the parallel filters. By storing 4x4 pixel blocks used for the computation of parallel filters into different SRAM blocks, the data for horizontal and vertical filtering can be accessed without conflicts. Therefore, the maximum on-chip SRAM throughput is maintained during the filtering computation. The proposed architecture can process video of 16K (15360x8640) at 60fps in real time. The VLSI implementation of the proposed architecture operates at 140MHz and the gate count is 244K in TSMC 65nm process. Compared with the previous works, the proposed work shows the performance improvement of 90%.

자궁경부암 세포를 위한 광학 모니터링 시스템의 설계 및 분석 Design and analysis of an optical monitoring system for cervical cancer cells

https://doi.org/10.5370/KIEE.2020.69.11.1761

이훈(Hun Lee) ; 오지현(Ji-Hyeon Oh) ; 박건석(Gun-Seok Park) ; 최세운(Se-woon Choe)

Flow cytometer is a device for precise analysis of cells by measuring scattering of light and fluorescence according to the cell type. It is used for various purposes in many fields such as molecular biology, immunology, and pathology. However, flow cytometry is expensive and inconvenient in terms of maintenance when simple comparisons between cells are performed or when only simple measurement such as the number of cells is required. In this study, we designed a system that can measure forward scatter, side scatter, and fluorescent scatter using LED and photodiode. As a result, it was possible to measure the fluorescence scattering of cervical cancer cells stained with Calcein AM or DiD, and a high linear relationship with the number of cells was confirmed.

활선상태의 전력용 콘덴서 및 직렬 리액터 용량 측정방법 A method for static capacitor and series reactor capacity measurement of live wire state

https://doi.org/10.5370/KIEE.2020.69.11.1767

박성구(Sung-Koo Park) ; 한동균(Dong-Gyun Han) ; 이진락(Jin-Rak Lee) ; 전명수(Myung-Su Jeon) ; 김성철(Seong-Cheol Kim)

As the static condenser used to improve the power system power factor is installed, a voltage distortion due to inflow of harmonics occurs. In order to reduce harmonics, a series reactor is installed and operated. However, the fault countermeasures due to the burnout of the serial reactor is insufficient. In this paper, a method for measuring the condenser capacity of a live wire status and a series reactor capacity was proposed. In this paper, we propose a method of measuring the capacity of the condenser in the live wire state and the capacity of the series reactor, and provide the basis data for predicting the deterioration state and the degree of performance degradation of the condenser and the series reactor. also, to verify the proposed capacitor capacity measurement method, the capacity measurement method and the effectiveness of the measurement equipment were verified by conducting a demonstration test in connection with the capacity measurement equipment at a demonstration site where L and C values of live wires.

3상 유도전동기 기동전류의 배수에 따른 역률 변화에 관한 연구 A Study on the Variation of the Power Factor according to the Multiples of the 3-phase Induction Motor Starting Current

https://doi.org/10.5370/KIEE.2020.69.11.1773

김종겸(Jong-Gyeum Kim)

Induction motor is one of the most representative inductive loads. Induction motor is a rotating electric device unlike a transformer, and its power factor is different between starting and normal operation. In particular, the power factor of starting is lower than during normal operation. This is because the proportion of reactive power required to form a rotating magnetic field at the initial starting is higher than the amount of active power associated with the output. Induction motor is mainly used in places that require a fast rotation speed. Induction motor can be quickly acquired at rated torque when directly starting, but have a disadvantage in that a voltage drop occurs due to high current generated at starting. In addition to affecting the voltage drop, the size of the starting current can also affect the power factor until the rated speed is reached according to the duration. In this study, we analyzed changes in power, power factor, and voltage drop in the process of reaching the rated speed from starting when the multiples of the starting current were different for induction motors of the same capacity.

태양광 아크차단기 시험을 위한 기반 아크발생장치 개발 Development of UL1699B based DC Arc Generator for Photovoltaic Arc Fault Circuit Interrupter Test

https://doi.org/10.5370/KIEE.2020.69.11.1778

박광묵(Kwang-Muk Park) ; 방선배(Sun-Bae Bang) ; 박진영(Jin-Young Park) ; 홍성준(Seong-Jun Hong) ; 이순형(Soon-Hyung Lee)

In this paper, the development of a DC arc generator that is applicable to DC AFCI development and suitable for UL1699B test conditions is presented. The DC arc generator consists of a motor control system, an electrode system, an arc generator circuit. By applying an automated system using a motor and a linear actuator, the accuracy of the control such as electrode spacing has been improved. As a result of conducting an experiment on the developed product, the arc was successfully generated, and the minimum arc current according to the UL1699B test condition was satisfied. In addition, it was proved that DC arc characteristics can be analyzed through data such as arc voltage and arc current according to variables such as electrode spacing. The developed DC arc generator is expected to be used for research such as arc characteristics analysis and modeling, testing and product standardization under various conditions.

전기철도 유도전압 계산 알고리즘 개선 연구 A Study on the Improvement of Electrified Railway Inducing Voltage Calculation Algorithm

https://doi.org/10.5370/KIEE.2020.69.11.1785

최경(Kyung Choi) ; 최황규(Hwang-Kyu Choi) ; 이상무(Sang-Moo Lee) ; 이향범(Hyang-Beom Lee)

An improved algorithm to predict the induced voltage at the communication line by the electrified railway is presented, and the effects of the revised factors are reviewed and a verification through field measurement is performed. In addition, through this research process, we could find points to note about the preparation of input data. As a result of expanding the number of parallel conductors used to apply the multi-conductor calculation method according to the actual system, and applying the proper impedance calculation formula according to the position of the conducting line, a reduction ratio of 41-50% compared to the existing program is obtained. Field surveys are conducted to verify the effectiveness of this program, and very valid results are obtained that match the measurement situation. Therefore, the program with this algorithm can be applied practically in predicting and taking prevention in advance of dangers caused to communication facilities before railway construction.

데이터마이닝 기법을 이용한 전철전력설비 이상상태 데이터 분석 Anomaly Data Analysis of Electric Railway Facility using Data Mining Method

https://doi.org/10.5370/KIEE.2020.69.11.1795

신승권(Seung-Kwon Shin) ; 김재원(Jae-Won Kim) ; 조규정(Gyu-Jung Cho) ; 정호성(Ho-Sung Jung) ; 김형철(Hyung-Chul Kim)

It is necessary to develop a novel technology for predicting and diagnosing anomaly conditions of the railway power system, such as voltage drop and distortion so as to prevent a fault due to a power outage of the railway power system during railroad operation. Therefore, for intelligent management and maintenance of electric power equipment for railway system, an algorithm for an anomaly condition monitoring system based on real time TEO information was developed, and field installation for performance verification of the developed module was completed. In this paper, we describe the data mining process of a real-time monitoring system for anomaly conditions of the railway power system and the process of verifying the operation of the monitoring system.