• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 E
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• pp.2274-2276
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• 1999

In this work, temperature rise and eddy current distribution on the enclosure and conductor of 3 pole gas insulated switchgear were investigated using analytical and experimental measures. The design of the diameters of the conductors and the enclosures of a meal clad gas insulated switchgear is primarily based on the insulation requirements. It is very difficult problem to predict the temperature rise of enclosed switchgear due to the complexity of the phenomena of heat transfer and existence of eddy current loss. To overcome this situations, we focused on the eddy current distribution on the enclosure of switchgear caused by high current 3 pole conductor as a fundamental basis. The experimental results about temperature distribution of 3 pole gas insulated switchgear were reported and measurements are compared with predictions of three-dimensional thermal model for eddy current analysis. As a result, three dimensional numerical analysis found to be in close relationship with experimental results and thermal model is efficient to predict the abnormal temperature rise in switchgear.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.196-201
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• 2008

In DC traction systems, a part of feedback current returning through rails becomes leakage current, illumination on a metal laid underground results from the leakage current to ground. To prevent the leakage current on rails, feedback rails almost have insulated with the ground. Insulation between rails and the ground causes that the earth method changes a isolated method in DC traction systems. the rail potential rise results in the isolated method. the rail potential rise causes an electric shock when a person touches the ground and rolling stock. To decrease the rail potential rise and leakage current, there are methods for reducing the feedback resistance and current of rails, increasing the leakage resistance, decreasing the distance between substations. But it are necessary to forecast and analyze the rail potential and amplitude of leakage current. In this paper, we modeled DC traction systems and feedback circuit to simulate the rail potential and amplitude of leakage current using PSCAD/EMTDC that is power analysis program, forecasted the rail potential and amplitude of leakage current about changing various parameters in the electric circuit. By using the simulation model, we easily will forecast the rail potential and amplitude of leakage current in case of a level of basic design and maintenance in electric railway systems, valuably use basic data in case of system selection.

• 한국전기전자재료학회논문지
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• 제28권1호
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• pp.40-45
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• 2015

Electrode systems: a protrusion on conductor (POC), a protrusion on enclosure (POE), a crack in epoxy plate and a free particle (FP) were fabricated to simulate insulation defects in a gas insulated switchgear (GIS). $SF_6$ gas was filled in the electrode systems by 3 bar and/or 5 bar, respectively. Partial discharge (PD) pulses were detected through a $50{\Omega}$ non-inductive resistor. A calibration test was carried out according to IEC 60270, and the sensitivity was 0.25 pC/mV. PD pulses were distributed in the phase of $50^{\circ}{\sim}135^{\circ}$ and over 95% of them existed in the phase of $55^{\circ}{\sim}120^{\circ}$ for the POC. PD pulses were distributed in the phase of $230^{\circ}{\sim}310^{\circ}$ and over 90% of them existed in phase of $220^{\circ}{\sim}300^{\circ}$ for the POE. PD pulses occurred in the phase of $40^{\circ}{\sim}60^{\circ}$ and $220^{\circ}{\sim}300^{\circ}$ for the crack, and pulse counts were 25% higher in negative polarity than in positive polarity. PD pulses were distributed in every phase unlike to other three electrode systems and the peak magnitude was measured at $118^{\circ}$ and $260^{\circ}$ for the FP. As described above, PD pulses were observed in positive polarity for the POC, in negative one for the POE, in both one for the crack and the FP. In conclusion, it is expected that the identification rate of defect type can be improved by considering the polarity ratio of PD pulses on the PRPDA method.

• 산업경영시스템학회지
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• 제31권3호
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• pp.117-124
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• 2008

Ultra-high voltage transformer industry has characteristic of small quantity batch production system by other order processing unlike general mass production systems. In this industry, observance of time deadline is very important in market competitive power security and company continued existence. The transformer winding is a process that rolls a coil is coated with an electric insulation material in order to generate the required voltage using the voltage fluctuation. The winding process is very important production process in the extra-high voltage transformer manufacturing industry because winding process is core process that occupy weight about half of whole process and is process that decide current ratio of transformer. This paper proposes a statistical calculation and control method of planned leadtime on the basis of real data and informations for the A company in transformer winding process. Moreover, we develop unit process scheduling system.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.102-107
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• 2009

Window system is an essential component for lighting, ventilation and thermal environment in buildings. Moreover, as balcony extension in apartment houses become legalized, the performance requirements of window systems in balcony space are getting complicated. However, at this moment, five properties of the windows are used to represent the performance aspects of the system, including wind resistance, air tightness, water tightness, sound insulation, thermal resistance. And such single properties are not capable to express the performance of a space with the window systems in terms of performance concept. A performance analysis with wholistic approach is required to see the effect of the window system in built environment. Thus, performance-based approach should be established, which will be able to evaluate the goal/function and comfort of occupants/owners. As the first step to develop the performance indicator for the window systme for balcony space, this study conducts a survey to find the required performance aspects. A complete set of performance-based indicators will be developed with verification methods in the later stage of research.

• 한국초전도ㆍ저온공학회논문지
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• 제12권1호
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• pp.61-65
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• 2010

To develop the thermal analysis method for the thermal behavior of HTS power cable system, cooled with sub-cooled liquid nitrogen, new thermo dynamic model for HTS cable system is introduced. The introduced thermal model is mainly modified from the thermal circuit following to IEC60287 for underground power cable systems such as XLPE or paper wrapped insulation cables. The thermal circuits for HTS cables are similar to the forced cooled underground cable system but the major thermal parameters and the configuration is apparently different to the normal cable systems so there has been no proposals in this field of analysing method. In this paper, 154kV HTS cable system has been introduced as an aspects of thermal models and a thermal circuit is proposed for the fundamentals on the dynamic rating systems for the HTS cable system. By using the thermal circuit developed in this paper, the optimal controls on the sub-cooling system's capacity become possible and it is expected to make the efficiency of HTS cable higher than conventional static controls.

• 한국건축친환경설비학회 논문집
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• 제12권6호
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• pp.531-542
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• 2018

Building energy demands have highly risen in modern society; thus, It is necessary to reduce building energy demands especially commercial buildings adopting a curtain wall architecture. Curtain wall architectures have a high ratio of windows which is a vulnerable in heat insulations as cladding. In order to complement insulation performance of windows in these buildings, there are various methods adopted often such as installing blinds, wing wall and films. There are two suggestions of this paper. 1) WWR (Window-to-Wall Ratio) makes a impaction of energy demands in buildings. 2) Another one is an efficiency of blind systems which are installed in buildings in order to reduce cooling demands. It is also critical to make fundamental model for low-energy building construction by processing a lot of simulation As a result by this study, 1) an external blind system is more useful for reducing cooling energy demands rather than an internal blind system. 2) Buildings which have a large window require more amount of cooling demands. In case of WWR 45%, it needs more cooling energy rather than WWR 15% model's 3) Adopting blind system would reduce energy demands. WWR 45% model with external blind systems reduces about 4% of cooling energy demands compared to same model without any blind systems.4) it is necessary to study an efficiency of blind systems combined with renewable energy and it will be possible to reduce more energy demand in building significantly.

• 한국인터넷방송통신학회논문지
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• 제15권4호
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• pp.199-203
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• 2015

산업의 발전과 더불어 전력에 대한 수요량이 증가하고 있다. 이에 따라 전기의 생산 및 송전 용량이 커지고 시설이 대규모화될 뿐만이 아니라 높은 신뢰성으로써 동작할 것을 요구받고 있다. 전기의 생산 및 공급 과정에서 요구 되는 높은 신뢰성은 산업 사회의 필수적인 요소라고 할 수 있다. 설비의 사고 및 정전 사고 등은 높은 전기적 의존을 가진 고도 산업 사회에 막대한 경제적 손실 및 장애를 가져다준다. 이 논문에서 운전 중 케이블의 부하 전류와 수명과의 상관 관계에 대한 기초 연구를 제시한다. 본 연구를 위하여, 절연 저항과 부하 전류를 측정하기 위한 CT와 온도 측정 장치를 운전 중인 6.6 kV 케이블 시스템에 설치하였다. 측정 장치는 동작한지 약 20년이 경과한 케이블 시스템에 설치 운영 중이다. 대부분 케이블의 절연 저항은 한계 이상의 값을 나타내었으므로, 잔여 케이블 수명을 발견하기 어려웠으며, 부하 전류는 거의 변동이 없는 시스템이었다. 주변 온도는 $15{\sim}25^{\circ}C$로서 변동폭은 매우 적었다.

• Tribology and Lubricants
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• 제35권4호
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• pp.206-214
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• 2019

This study investigates alternative refrigerants and refrigerant oils as well as the tendency of protecting the global environment in view of automobile air-conditioning systems. Since decades, the R12 refrigerant is not used in automobile air-conditioners because of the ozone depletion potential (ODP) problem, and for the last 20 years, the ODP-free R134a refrigerant is leading the new automotive air-conditioning market. However, owing to its high global warming potential (GWP), the R134a refrigerant use in automobile air-conditioning system is also prohibited by law, and alternative refrigerants with a low GWP need to be proposed. Therefore, recently, the application of R1234yf, R152a, or other alternative refrigerants has started worldwide. By contrast, natural refrigerant R744 was introduced in the market several years ago by VDA (Verband Der Automobilindustrie), which is a German association in the automotive industry. This study also deals with refrigerant oils. For a long time, polyalkylene glycol (PAG) oil has been traditionally used with automobile air-conditioners, and polyolester (POE) oil is suitable for HEV, PHEV, and EV air-conditioning systems, where it is used by the electrically driven compressor owing to its excellent electrical insulation properties. Finally, PAG is an excellent lubricant for all the R134a, R152a, R1234yf, and R744 refrigerants, and has the advantage that it can be applied rapidly to alternative refrigerant air-conditioning systems.

• 한국인터넷방송통신학회논문지
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• 제14권4호
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• pp.197-203
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• 2014

발전소의 전력 케이블 시스템에서 발생할 수 있는 사고를 예측하고 방지하는 기술이 필요하다. 사선 상태에 있는 케이블의 동작 특성을 진단하기 위하여 부분방전 및 $tan{\delta}$ 법이 사용되고 있으나, 케이블이 갖고 있는 문제점들을 사전에 발견하기란 쉬운 일이 아니다. 이 논문에서 우리가 연구한 케이블은 (주)서부 발전소에서 설치되어 운전 중인, 발전 운영에 핵심 역할을 하는 6.6kV 고전압 배전 선로이다. 케이블의 온도 및 전류를 측정하고, 이를 바탕으로 절연저항을 측정하기 위한 장치를 개발하였다. 이 장치를 발전소 현장에 시험 설치를 하였고, 동작 중인 케이블의 수명을 평가하기 위한 동작특성의 진단을 성공적으로 마무리 하였다. 진단 데이터를 분석 평가함으로써 단기적으로는 운전 중 6.6kV 케이블 시스템의 고장상태를 파악하는데 활용되며, 장기적으로는 발전소 부하에서의 6.6kV 케이블 시스템의 설치 및 운영에 있어서 원가를 절감하기 위한 노력에 기여하고자 한다.