• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.603_604
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• 2009

HTS tape is developed for the purpose of being applied to the power cable, motor and generator, etc. The resistance of conventional power cables is not changed a lot by over current condition. But HTS(High temperature superconductor)power cable has some different properties. The impedance of superconductor is changed due to the magnitude of current, temperature, and magnetic field. And the characteristics analysis of HTS power cable under many kind of fault conditions are important to apply real system. In addition the magnitude of over current is 10 times larger than rated current. In this paper, the characteristics of HTS power cable are analyzed when over current flows. Model cable used 2G wires was made and experimented. The results will be helpful to manufacture real HTS power cable.

• 설비공학논문집
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• 제4권4호
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• pp.263-276
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• 1992

The transmission current in a power cable is determined under the condition of separate pipe cooling. To this end, the thermal analysis is conducted with the standard condition of separate pipe cooling system, which constitutes one of the underground power transmission system. The changes of transmission current in a power cable with respect to the variation of temperatures and flow rates of inlet cooling water as well as the cooling spans are also determined. As a consequnce, the corresponding transmission current is shown to vary within allowable limit, resulting in the linear variation of the current for most of the cable routes. The abrupt changes of current, however, for the given flow rate of inlet cooling water in some cooling span lead to the adverse effects on the smooth current transmission within the underground power transmission system. In practice, it is expected that the desinging of the separate pipe cooling system in conjunction with the evaluation of system capacity should take into account the effects of design condition on the inlet cooling flow rate.

• Journal of Power Electronics
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• 제13권5호
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• pp.746-756
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• 2013

The modularized subunit of an electronic power transformer (EPT) is a series connection of two H-bridge voltage-source converters and a DC-DC converter with a high-frequency isolation transformer (HFIT). On the basis of cascading and paralleling the modularized subunits, EPT can be used in high-voltage and large-current applications in the power system. This paper discusses the steady state analysis of the modularized subunit of EPT. Theoretical analysis considers the influences of the two H-bridge voltage-source converters on the two sides of the DC-DC converter. We deduce the formulas of the theoretical calculation on the internal electrical characteristics of EPT (e.g., the voltages of the DC-bus capacitor and the primary side peak current of the HFIT). This paper provides guidance on the design and selection of EPT key elements (e.g., the DC-bus capacitors and HFIT). Experimental results are obtained from a single subunit of a laboratory model rated at 962 V, 15 kVA. All calculations, simulations, and experiments confirm the theoretical analysis of the subunit of EPT.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 C
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• pp.1028-1030
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• 1999

전 세계적으로 송전 용량의 증대 요구에 따라 송전 시스템이 초고압화 되어 가고 있으며 환경친화성 및 여러 특성에 있어 OF(Oii filled) 케이블에 비하여 우수한 성능을 지닌 XLPE(Crosslinked Polyethylene) 케이블의 사용이 급속하게 증가하고 있는 추세이다. 최근 345kV급 이상의 XLPE 케이블 시스템 개발이 해외 선진업체들에 의해 활발히 진행되고 있으며 이의 평가를 해외공인 인증기관에서 수행하여 개발된 제품의 디자인 검증 및 장기간 신뢰성을 입증하고 있다. 이러한 추세에 맞추어 LG 전선은 400kV 케이블 및 접속함의 사내 개발시험후 해외공인 인증기관인 네덜란드의 KEMA에서 IEC 62067에 따른 인증시험을 완료하여 개발된 제품의 높은 신뢰성을 인증 받았으며, 자사의 초고압 기술을 한 단계 상승시켜 세계 선진업체들과 경쟁할 수 있는 발판을 마련하였다.

• KEPCO Journal on Electric Power and Energy
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• 제1권1호
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• pp.67-71
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• 2015

The concept known as Vehicle-to-Grid (V2G) is to provide power to help balance loads by charging at night when demand is low and sending power to the grid when demand is high. Therefore, it is important to model the cost-benefit characteristics of Electric vehicle(EV)'s operation considering the negawatt market in real time. This paper proposes a methodology to formulate the various costs and economic benefits for sending the EV's power back to the grid, including a concept of inconvenience costs caused by operating the EV as a battery. This paper also introduces the general decision-making process based on the cost-benefit analysis in order to simulate the reasonable participation of V2G service. In the case study, it is confirmed by two-case simulations that the proposed approach is useful to help EV owners' decision-making. In the future, it is expected that the proposed methodology can be used as a decision-making guideline to help prepare the EV' power transmission.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
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• pp.1216-1218
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• 2005

A high temperature superconducting power transformer gets its advantages over the conventional ones when the rated capacity of the HTS transformer becomes 30 MVA or more. The standard capacity of the recent 154 kV/ 22.9 kV power transformer is 3 phase 60 MVA in Korea which means that the rated current of the secondary becomes more than 1,500 amps. Considering the current capacities of the HTS wires being developed recently, it is inevitable to use the HTS wires in parallel in order to be applied to the power transformer. But nonuniform distribution of currents and large AC losses are major problems in parallel HTS windings setting aside the difficulties of making parallel windings. To solve these problems, several kinds of multiply laminated HTS wires were fabricated and tested for the application of these multiple wire to an HTS power transformer. Test results were compared with that of each other and the best were selected for the application to an HTS power transformer.

• 한국전자파학회논문지
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• 제12권3호
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• pp.409-426
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• 2001

본 논문은 유한차분 시간영역 해석법(Finite-Difference Time-Domain Method)을 사용하여 900 MHz용 휴대폰으로부터 방출된 전파의 인체 두부(頭部)에 흡수된 전력량을 산출하였고, 흡수전력으로 인한 두부내의 온도 상승량을 계산하였다. 이를 위하여 인체두부를 5층 매질로 모델링하였고, 휴대폰은 금속상자에 부착된 모노폴안테나로 모델링하였다. 모델링에 사용된 인체두부와 휴대폰의 크기는 상용의 값을 사용하였다. 사용된 모노폴 안테나의 길이는 8.16 cm이고, 휴대폰의 출력은 상용 900 MHz의 600 mW을 사용하였다. 설정된 모델링하에서 인체의 위해(危害)정도를 알려주는 지수는 1 g, 10 g 평균 北 흡수율(SAR-Specific Absorption Rate)의 분포를 계산하였고 이에 따른 1g, 10 g 평균 온도 상승량을 계산하였다. 그 결과 비흡수율이 최대가 되는 지점은 인체 두부의 피부 부분이었고 최대 온도 증가 위치는 이보다 안쪽부분에서 나타났다. 인체 두부와 휴대폰의 이격거리에 따른 SAR과 온돈 상승량을 계산하였다.

• 한국표면공학회지
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• 제34권5호
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• pp.503-509
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• 2001

Thin films of hydrogenated amorphous silicon (a-Si : H) and hydrogenated amorphous silicon carbide (a-SiC:H) of different compositions were deposited on Si(100) wafer and glass by RF plasma-enhanced chemical vapor deposition (RF-PECVD). In the present work, we have investigated the effects of the RF power on the properties, such as optical band gap, transmittance and crystallinity. The Raman data show that the a-Si:H material consists of an amorphous and crystalline phase for the co-presence of two peaks centered at 480 and $520 cm^{-1}$ . The UV-VIS data suggested that the optical energy band gap ($E_{g}$ ) is not changed effectively with RF power and the obtained $E_{g}$(1.80eV) of the $\mu$c-Si:H thin film has almost the same value of a-Si:H thin film (1.75eV), indicating that the crystallity of hydrogenated amorphous silicon thin film can mainly not affected to their optical properties. However, the experimental results have shown that$ E_{g}$ of the a-SiC:H thin films changed little on the annealing temperature while $E_{g}$ increased with the RF power. The Raman spectrum of the a-SiC:H thin films annealed at high temperatures showed that graphitization of carbon clusters and microcrystalline silicon occurs.

• 한국항행학회논문지
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• 제24권4호
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• pp.261-266
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• 2020

항공기 장착물에 KW급 전력변환장치가 탑재되는 경우, 전력 변환 시 발생하는 대량의 발열에 대한 방열설계가 고려되어야 한다. 적절한 방열을 하지 못하는 경우, 장비 오작동 및 화재의 우려가 발생하며 이는 항공기 운항에 있어 치명적인 요인이 될 수 있다. 본 논문은 항공기 장착물에 탑재되는 KW급 전력변환장치의 방열설계에 관하여 기술하였다. 전산해석을 통한 설계 및 제작 후 시험을 수행하였으며, 고전력 변환에 따른 발열부품의 급격한 발열 현상을 확인하여 해석 모델을 보정하였다. 모델 보정 후 방열구조가 개선된 형상으로 설계를 개선하였으며, 미 군사규격인 MIL-STD-810G 의 고온동작 시험을 수행하여 개선된 형상의 타당성을 검증하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 19-21 Oct. 1992
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• pp.292-296
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• 1992

There are lots of disturbance in the super heater temperature control system of power plant boiler as follows. 1.Burner light off. 2.Excess Air. 3.Burner tilt. 4.G.R fan flow. Temperature control system of super heater in the power plant has delay time about 5 min. So it is difficult to control the super heater temperature in the power plant. This paper show us the application of domestic development DCS to control the super heater temperature in seoul #5 thermal power plant unit.