• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.273-274
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• 2009

현재 가로등의 93.3[%]를 차지하고 있는 나트륨램프는 색상이 적황색이며, 시력에 장애와 피로감을 주어 인체에 해로우므로 고효율 램프로 교체되고 있으며 백열전구는 전력을 많이 소모하고 잦은 고장으로 빈번한 대체와 유지보수를 필요로 하므로 LED를 선택하면, 유지보수 비용과 안전성, 에너지 효율성면에서 큰 강점을 갖는다. 본 연구에서는 에너지 효율이 높은 LED 가로등 제작을 위한 모듈을 제작하여, 열적, 광학적 분석을 하였다. 동작 150분 후, LED Module의 PCB기판 6 Point에서 Thermal Grease와 Thermal Pad의 처리에 의한 열적 변화를 측정하였으며, Thermal Grease 처리는 Thermal Pad 보다 평균 3 $[^{\circ}C]$ 정도 낮은 35 $[^{\circ}C]$결과를 얻었으며, 제작된 LED Module의 광학적평가의 결과는 10 [m] 높이에서 $20\times20\;[m^2]$ 면적에 조사된 조도의 최대,최소값은 10.9~0.6 [lx]이고, 주로 10~5 [lx] 값이 조도의 면적을 차지하였으며, 곡선은 옆으로 넓게 펼쳐진 곡선을 나타내었다.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.758-759
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• 2011

대용량 교류발전기는 전력계통의 중요한 요소이다. 발전기의 사고 중 가장 많이 발생하는 부위는 전기자 권선이다. 보호제어시스템의 효율적인 운용과 향후 차세대 ECMS를 위하여 교류발전기의 보호계전분야에 대한 연구가 필요하다. 해외에서 교류발전기의 단락 및 지락 보호에 관한 Standards들이 제정되었고 발전기의 상세 모델링과 내부권선 사고 모의에 대하여도 계속 연구 중에 있다. 본 논문에서는 고정자의 주보호인 비율차동계전방식의 검출방법, 동작영역 및 특성곡선과 정정치 등을 조사한 후 내부 외부고장의 경우 동작 시뮬레이션을 수행하였다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.9
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• pp.1500-1506
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• 2008

In this paper, we proposed new reliability characteristic curve, which-can clearly show reliability property of transmission and substation system considering uncertainty such as frequency and duration of device fault. It express the relationship of duration of load curtailments, demand not supplied, and energy not served as “ y = $ax^{-1}$ " curve. and we proposed the method, which can objectively assess reliability of transmission and substation system using proposed characteristic curve as new reliability index. In this method, we used energy index of reliability(EIR) as a criterion of assessment. Finally, we performed a variety of case study for KEPCO system in order to verify usefulness of proposed method.

• Nuclear Engineering and Technology
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• v.15 no.1
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• pp.41-49
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• 1983

A computer code, BERD (Bayesian Estimation of Reliability Data), has been developed and tested in order to update the data for the reliability analysis of safety related systems in a specific nuclear power plant. The code has been used to derive the plant-specific data for reliability analysis of the auxiliary feedwater system of a pressurized water reactor. The prior information for components selected was taken from the U.S. Reactor Safety Study, WASH-1400, and the operating experiences from published licensee event reports. The results show that the updated data are well fitted to log-normal distribution curves and the error factors are reduced significantly.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.151-154
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• 2005

Tilting train improves a traveling velocity through giving a tilt the car-body without ride comfort deterioration In curve. Dynamic behavior in deceleration will show quite another feature in constant velocity, In this study, we see through the dynamic behavior due to a variation of braking force in Korean Tilting Train. Hence we compose of 3D dynamic model, as well as we check upon the property in service braking condition and unique braking condition with a fault system. This study has the meaning with reference data of developing Korean Tilting Train test traveling.

• Bulletin of the Korea Photovoltaic Society
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• v.7 no.2
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• pp.7-15
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• 2021

태양광 발전소에 대한 성능을 평가하기 위해서는 IEC 61724-1에 적합한 계측장치를 설치하고 데이터를 수집하여 평가하는 것이 일반적인 방법이다. 본 논문에서는 태양광발전소 현장에서 DC 어레이 성능을 평가하기 위한 방법을 제시하였다. 측정 일사량과 같은 환경정보 값과 태양광 DC 어레이 전압-전류 특성 곡선을 이용해 일사량에 따른 출력모델 식을 도출하였다. 도출된 모델 식은 태양전지 셀의 종류나 버스바에 따라서 차이가 발생되므로 기존의 태양전지 셀 등가회로 수식을 반영한 시뮬레이션 모델식이 적절히 변경되어야 함을 실험을 통해 검증하였다. 주기적인 진단 평가를 실시하지 않는 국내외 태양광 발전소는 성능저하가 발생된 상태로 운전되는 경우가 다수 일 것이다. 대부분의 관제모니터링을 시스템은 미쓰매칭 손실 평가분석이 불가능하며 운전상태 모니터링 하는 시스템이 대부분이다. 이에 태양광 발전소의 효율적 운영을 위해서는 현장진단 장치를 이용한 주기적 성능진단 평가나 발전소 데이터의 손실평가 분석 기술의 개발이 필요할 것이다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.36 no.4
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• pp.273-282
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• 2023

Probabilistic safety assessment (PSA) has been widely used to evaluate the seismic risk of nuclear power plants (NPPs). However, studies on seismic PSA for process plants, such as gas plants, oil refineries, and chemical plants, have been scarce. This is because the major disasters to which these process plants are vulnerable include explosions, fires, and release (or dispersion) of toxic chemicals. However, seismic PSA is essential for the plants located in regions with significant earthquake risks. Seismic PSA entails probabilistic seismic hazard analysis (PSHA), event tree analysis (ETA), fault tree analysis (FTA), and fragility analysis for the structures and essential equipment items. Among those analyses, ETA can depict the accident sequence for core damage, which is the worst disaster and top event concerning NPPs. However, there is no general top event with regard to process plants. Therefore, PSA cannot be directly applied to process plants. Moreover, there is a paucity of studies on developing fragility curves for various equipment. This paper introduces PSA for gas plants based on FTA, which is then transformed into Bayesian network, that is, a probabilistic graph model that can aid risk-informed decision-making. Finally, the proposed method is applied to a gas plant, and several decision-making cases are demonstrated.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.11 no.4
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• pp.460-466
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• 2018

With the development of information technology, the scale of computer software system is constantly expanding. Reliability and cost of software development have a great impact on software quality. In this study, based on the software failure interval time data, a comparative analysis was performed on the characteristics of the software development cost model based on the lifetime distribution following the Type-2 Gumbel and Erlang distribution in the NHPP model. As a result, the trends of the cost curves for the Go-Okumoto model and the proposed Erlang model and the Type-2 Gumble model both decreased in the initial stage and gradually increased in the latter half of the failure time. Also, Comparing the Erlang model with the Type-2 Gumble model, we found that the Erlang model is faster and more cost-effective at launch. Through this study, Software operators should remove possible defects from the testing phase rather than the operational phase to reduce defects after the software release date, it is expected to be able to study the prior information needed to understand the characteristic of software development cost.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.6
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• pp.533-541
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• 2011

This paper studies modeling of Jeju 80kV HVDC system and its controller by using PSCAD/EMTDC program. Reduced ac network is applied to verify interaction between ac network and dc system. Design parameter is applied to the converter transformer, harmonic filter and dc transmisstion line to simulate dc system. HVDC controller is divided into a rectifier controller and a inverter controller according to the converter operating mode. The inverter controller is composed of current control, voltage control and extingtion angle control. The rectifier controller is composed of current control and voltage control. Both controller has VDCOL characteristics so that current order is dependant on voltage variation. Step response, ac network single phase fault, three phase fault is simulated to verify the dynamic performance of controller model in both transient state and steady state.

• Journal of Korean Society of Steel Construction
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• v.29 no.1
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• pp.81-88
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• 2017

Residual stress is defined as stress that already exists on a structural member from the effects of welding and plastic deformation before the application of loading. Due to such residual stress, welded H-section compression members under centroidal compression load can undergo buckling and failure for strength values smaller than the predicted buckling load and specified compressive strength. Therefore, this study was carried out to evaluate the effect of residual stress from welding on the determination of the buckling load and specified compressive strength of the H-section compression member according to the column length variation. A three-dimensional nonlinear finite element analysis was performed for the H-section compression member where the welded joint was fillet welded by applying heat inputs of 3.1kJ/mm and 3.6kJ/mm using the SAW welding method.