• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.1
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• pp.116-124
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• 2009

This paper proposes a new Artificial-Intelligent(AI) Power Quality(PQ) diagnosis algorithm using Discrete Wavelet Transform(DWT), Fast Fourier Transform(FFT), Root-Mean-Square(RMS) value. The developed algorithm is able to detect and classify the PQ problems such as the transient, the voltage sag, the voltage swell, the voltage interruption and the total harmonics distortion. The 15.36[kHz] sampling frequency is used to measure the voltages in a power system. The measured signals are used for DWT, FFT, RMS calculation. For AI diagnosis of the PQ problems, a simple multi-layered Artificial Neural Network(ANN) with the back-propagation algorithm is adopted, programmed in C++ and tested in PSIM simulation studies. Finally, the algorithm, which is installed in MP PQ+256 with TI DSP320C6713, is proved to diagnose the PQ problems efficiently.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.4
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• pp.81-94
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• 2010

This paper presents a high efficiency resonant asymmetrical half-bridge flyback converter. The primary half-bridge circuit of the converter operates by a soft-switching type using the asymmetrical pulse-width modulation (PWM) method with the resonant capacitance and transformer leakage inductance. The secondary flyback circuit of the proposed converter utilizes a synchronous rectifier, which operates by a new voltage-driven method with a simple drive circuit. Thus the proposed converter improves the total efficiency. This paper explains the operational principle of the proposed converter by each mode and shows the converter design consideration and a design example for the prototype converter, respectively. After that, the proposed simple driving technique of the synchronous rectifier by a voltage-driven method is explained, briefly. The designed prototype converter has wide input voltage (AC $V_{in,rms}$=75~265[V]), 5[V] DC output voltage, and 100[W] output power. To verify the excellent performance of the proposed converter, the designed prototype is implemented and experimented. The good performance of the proposed converter is shown through the experimental results.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.5
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• pp.72-77
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• 2006

This paper presents a comparison of experimental value by electrolytic tank experimental apparatus and calculated value by CDEGS program for potential rise of structure. When a test current flowed through structure models, potential rise was measured and analyzed for types of structure using the electrolytic tank experimental apparatus in real time, and was computed by means of CDEGS program. The structure models were designed and fabricated with four types on a scale of one-one hundred sixty. When the experimental data were compared with the theoretical values, the similar profile was shown. Therefore, the confidence of measurement was obtained. Potential rise was the lowest value at electric cage type(structure model B). The distributions of potential rise are dependent on the resistivity and absorption percentage in concrete attached to structure.

• Journal of the Korea Convergence Society
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• v.13 no.2
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• pp.249-255
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• 2022

This study proposed an analysis framework for real-time prediction of CNC processing defects using machine learning-based models that are recently attracting attention as processing defect prediction methods, and applied it to CNC machines. Analysis shows that the XGBoost, CatBoost, and LightGBM models have the same best accuracy, precision, recall, F1 score, and AUC, of which the LightGBM model took the shortest execution time. This short run time has practical advantages such as reducing actual system deployment costs, reducing the probability of CNC machine damage due to rapid prediction of defects, and increasing overall CNC machine utilization, confirming that the LightGBM model is the most effective machine learning model for CNC machines with only basic sensors installed. In addition, it was confirmed that classification performance was maximized when an ensemble model consisting of LightGBM, ExtraTrees, k-Nearest Neighbors, and logistic regression models was applied in situations where there are no restrictions on execution time and computing power.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.18 no.2
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• pp.87-100
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• 2022

Unit capacity factor (utilization rate) of nuclear power plants (NPPs) is an important performance indicator. Since the first commercial operation of Kori Unit 1 began in April 1978, the utilization rate of domestic NPPs has gradually increased, reaching 90% from the end of the 1990s. However, due to various issues such as the Fukushima accident in 2011, corrosion of the CLP, the utilization rate dropped to 65~80%. In the early 1980s, the utilization rate of the U.S. NPPs was around 60%. However, since 2004, it has been consistently maintained above 90%. Therefore, in this study, we first examined the causes of declining the utilization rate in domestic NPPs. Next, the significances of the utilization rates are reviewed in five aspects: investment capability, electricity rate, safety and export, etc., with discussion on the current status of the utilization rates in the U.S. Based on this, three key factors are derived as the reasons of the increasing: equipment reliability program, on-line maintenance and the pursuit of institutional rationality. And finally, by synthesizing above results, the measures for increasing the utilization rate of domestic NPPs are proposed in terms of equipment management, institutional improvements, and personnel resources.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1372-1373
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• 2011

신재생에너지 발전기는 출력가변성이 크기 때문에 장기 전력수급계획 수립시 발전용량을 얼마로 할 것인가에 대한 불확실성을 내포하고 있다. 본 논문에서는 확률론적 신뢰도 기법에 기반하여 신재생 발전기가 공급신뢰도에 기여하는 용량산정 방법을 제안하고 우리나라 전력수급기본계획에 적용하는 방안을 살펴보았다. 국내 발전설비계획 수립에 사용하는 공급지장확률(LOLP)을 이용하여 신재생 발전기의 공급 신뢰도 기여용량을 산정하고 그 결과를 현재까지 사용해 온 신재생발전기 이용률에 기반한 기여용량 산정결과와 비교하였다. 특히 신재생발전원 중 우리나라에서 많은 부분을 차지하는 풍력 및 태양광에 대하여 용량가치를 산정하였다. 확률적 신뢰도기반 용량가치 산정법은 제5차 전력 수급기본계획 수립시 적용된 바 있으며, 좀 더 정밀한 산정절차를 수립하여 수급계획에 적용할 필요가 있다. 본 연구의 결과는 향후 수급계획 수립에 신재생 발전원의 정확한 용량가치를 산정하는 방식을 선정하는 데 참고자료로 활용될 수 있다.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.392-393
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• 2008

한전에서는 배전용 변압기의 부하관리를 위하여 전국사업소에 산재해 있는 변압기를 NDIS1) 부하관리 시스템으로 데이터 베이스화 하고, 각 변대에 수용되어 있는 고객의 월별 전기사용량을 추출하기 위하여 영업정보시스템과 연계하여 변압기, 배전선 개체관리는 물론 부하계산, 부하실적 및 부하예측 자료를 관리하고 있다. 이중 전등부하는 고객의 월간 사용전력량(kWh)과 최대부하(kVA)의 부하특성에 따른 상관 계수를 산정하여 이를 상관식에 적용하여 최대부하를 산출하고 있으며, 동력부하는 계약전력 및 종합수용률을 적용하여 부하전류를 계산하고 있으나 최근 고객의 냉방부하 급증으로 인하여 고객의 계약전력과 실제 설비용량과의 많은 차이가 발생하고 있어 변압기 관리에 어려움이 있고, 과부하로 인하여 변압기가 소손되는 사례도 발생하고 있다. 따라서 변압기 무선부하 감시시스템으로 측정한 결과를 토대로 변압기 이용율 계산의 정확도를 높이고 변압기 관리를 효율적으로 할 필요가 있다.

• Korean Journal of Organic Agriculture
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• v.31 no.3
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• pp.229-247
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• 2023

This study investigates the facility use status of smart farming farmers to improve facility use rate of farmers. To this end, a survey was conducted on smart farming farmers in Jeonnam province, and the main survey contents are as follows: facility use rate, the reasons for low facility use, the perception of the introduction and use of smart farming etc. As a result of the survey, many farmers have introduced smart farming facilities even though they do not have enough use capacity. Thus it is necessary to improve the use capacity of farmers. Second, the average facility use rate of farmers was 65.1%, and 37.5% of respondents did not use even 50% of smart farming facilities. To improve the use rate, education on how to use facilities and continuous consulting support for farmers are needed. And the largest number of farmers perceived the risk like crop damage or facility failure due to poor use of facilities. This means that risk management due to the smart farming facilities is important. Third, farmers answered that rapid and continuous repair service were the most important when using facilities. Thus it is important to foster rear industries such as maintenance companies to stably operate smart farming facilities.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.11a
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• pp.874-877
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• 2007

최근 건설 산업이 고도화, 지능화됨에 따라 건설자재정보의 효율적인 관리방안으로 RFID 기술을 이용하려는 연구 및 적용 사례가 증가 하고 있다. RFID(Radio Frequency Identification)란 라디오 주파수를 이용한 무선인식 기법을 뜻하는 것으로 건설자재에 RFID Transponder(이하 태그)를 부착하여 생산, 유통, 설비 등 전 과정의 정보 추적 및 관리가 가능하다. 그러나 RFID 시스템 특성상 전자기장이 형성되는 철골자재나 수분이 포함된 콘크리트, 도료(안료) 등의 자재에서는 RFID 적용이 쉽지 않다. 또한, 현재 사용 중인 RFID 장비마저도 표준화 되어 있지 않고 사용 주파수 대역 또한 각각 다르기 때문에 건설자재에 적용하기위한 RFID 시스템의 표준화 및 규격화가 절실하다. 본 논문에서는 건설자재에 RFID를 적용하기 위한 표준화 방향을 제시하는 기초 연구로써 목재, 철재 빔, 도료(안료), 콘크리트, 배관자재(철/동/PE)에 Passive Type의 일반(Pager) 태그, 금속 태그, 액체형 태그를 부착 매립하여 125KHz, 13.56MHz, 900MHz의 주파수 대역과 자재 물성별 인식거리 및 인식률 시험을 진행하여 건설자재에 RFID를 적용하기위한 표준 주파수 대역 및 재질에 따른 적정 태그를 제시하고자 한다.

• Journal of Bio-Environment Control
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• v.23 no.4
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• pp.371-375
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• 2014

This study was carried out to get the basic data to practically design an artificial light-used plant factory system for common ice plant (Mesembryanthemum crystallinum L.) cultivation. The adequate range of light intensity was $120-200{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ and the carbon fixed rates was $0.84nmolCO_2{\cdot}cm^{-2}{\cdot}s^{-1}$. When the planting density, light intensity, and yield were $0.0225m^2$ ($15{\times}15cm$), $200{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$, and 1,000 plants per day, the total number of the plants, cultivated area, and total light intensities were estimated as 25,000 plants, $563m^2$, and $140,625{\mu}mol{\cdot}s^{-1}$, respectively. About 153.2kW with 2,785 fluorescent lights (FL) needed for the electric power and the electricity charges was 2.46 million won for one month. At a harvest rate of 1,000 plants per day in closed-type plant factory, the light installation cost, total installation cost, and total production cost were 27.85, 83.56, and 100.27 million won, respectively. The production cost per plant including labor cost was calculated as 370 won, providing that the cultivation period was 25 days and marketable ratio was 80%. Considering the annual total expenses, incomes, and depreciation cost, the sales cost per plant could be estimated around 970 won or higher.