• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.2095_2096
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• 2009

송배전용 설비에 사용되는 애자의 신뢰성은 전기적인 절연성질과 기계적인 내구성 뿐만 아니라 애자가 설치된 송전선로의 오손에 의한 내환경성에 의해서도 결정될 수 있다. 지금까지 염분 및 분진이 심한 지역에서 오손물이 애자에 미치는 영향에 대한 연구는 전기적, 기계적 신뢰성에 영향을 미치는 오손물질의 성분 분석 등을 통해 저압과 고압의 환경에서 진행되어 왔다.[1] 본 논문에서는 2003년부터 우리나라에서 운전해 오고 있는 765kV 애자오손 신뢰성 검토와 미국 전력연구원(EPRI)에서 수탁받은 765kV 고분자애자 특성연구의 일환으로, 765kV 상용선로에 사용되는 애자류에 대한 장기열화특성을 연구하기 위해 765kV 실증 시험설비를 구축하였다. 아울러, 765kV 애자 장기열화특성 분석을 위한 기초연구로 염분 및 분진 오손도를 측정하여 765kV 환경에서 애자종류에 따른 오손 특성을 검토하였다. 그 결과, RTV 실리콘고무 코팅 애자가 자기 및 유리재 애자에 비해 염분 오손도 면에서 비교적 우수한 특성을 지님을 확인 할 수 있었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.1670_1671
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• 2009

산업경제구조의 변화로 경험이 풍부한 전문가들이 은퇴하고 경험이 적은 직원들이 그들의 업무를 대신하는 구조로 조직이 변화하고 있다. 동시에 녹색성장시대의 도래로 화석연료를 사용하는 설비에 대한 투자가 줄면서 점차로 노후화되는 경향을 보이고 있어 불필요한 운전 과도현상에서 기인된 극단적인 손상은 설비자체 및 전력공급계통 전체에 치명적이라고 할 수 있다. 따라서 석탄화력발전소 제어 시스템은 이러한 사안들을 안정적으로 이끌어 나가기 위한 중요한 요소로 저비용 고효율 발전소 유지를 위해 중점적으로 발전시켜 나가야 할 부분이다. 본 논문은 석탄화력발전소의 주구성요소인 보일러와 터빈을 제어하는 마스터 제어기의 복잡한 로직을 모델 기반의 간단한 로직으로 개발하여 시뮬레이션 한 결과를 실제 발전소에 적용하기 위한 내용을 기술하였다. 실제 발전소는 많은 위험요소들을 안고 있기 때문에 시뮬레이션에서 나타나는 급격한 제어동작을 수용할 수 없을 경우도 있으며, 실제 다른 많은 변수들이 제어불안정 요소로 작용할 수 있다. 차후 실제 적용한 결과는 예측제어의 사용과 같은 제어시스템 향상을 위한 개발과 운영효율 향상에 사용될 것이다. 튜닝 과정에서의 연구결과는 시간절약과 제어부분 결함제거 등 직원들의 전문지식 향상 등에 도움을 주게 될 것이다.

• 설비공학논문집
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• 제17권1호
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• pp.16-24
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• 2005

The goal of the present paper is to show the optimum design and operation conditions on 6 kW solar water heating system by using computer simulation with verified modelling. As the object functions, we took not only the amount of acquired and auxiliary heat but LCC, which has a relative importance and decisive role in economy. As expected, the maximum heat is acquired at the slope of collector with the equal degree to the latitude, facing the south. The capacity increase of the circulation pump and the storage tank lead to the increase of acquired heat and the decrease of auxiliary heat, but do not necessarily give economical advantages owing to additional electrical power consumption. In the present system, the minimum LCC can be obtained at the storage tank volume of 450 L and the mass flow rate of 0.344 kg/s.

• 설비공학논문집
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• 제22권6호
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• pp.337-344
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• 2010

Good plant-growth conditions can be achieved by means of using greenhouses. One of the main issues in greenhouse cultivation is energy savings through the development of high efficient heating and cooling system. GSHPs are one of the recommended systems to cope with this pending need. The aim of this study is to investigate the heating performance of ground source multi-heat pump system installed in a greenhouse under part load conditions. Daily average heating COP of the heat pump unit was very high by at least 7.4, because of relatively large condenser, evaporator, and mass flow rate through ground loop heat exchanger. However, the system COP, overall heating coefficient of the performance of the system with heat pump unit and GLHX, decreased drastically due to relatively large power consumption of circulating pump under part load condition. It is suggested that the technology to enhance the performance of the ground source multi-heat pump system for a greenhouse under part load conditions should be developed.

• 설비공학논문집
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• 제30권4호
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• pp.186-194
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• 2018

A ground-source heat pump system (GSHP) is more energy efficient than other heat-source systems because it uses annual constant underground and water temperatures. Especially, two-well geothermal systems using groundwater as the heat source can achieve higher performance than closed-loop geothermal systems. However, performance of two-well geothermal systems is decreased by occurring overflow according to scale during long-term operations. Therefore, this study presents a two-well pairing geothermal system that controls the groundwater level of a diffusion well. In addition, a two-well pairing geothermal system and an SCW geothermal system were installed, and a comparative analysis of cooling performance depending on system operation under the same load conditions was conducted. The result was that the average heat pump coefficient of performance (COP) of the two-well pairing system was 6.5, and the entire system COP was 4.3.

• 설비공학논문집
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• 제30권4호
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• pp.167-174
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• 2018

The geothermal heat pump systems were installed for heating and cooling of public buildings in Jincheon Eco-friendly Energy town. The heat pump system was operated at night to save on operational costs, and the cold heat was stored in thermal energy storage (TES). In this study, the performance of geothermal heat pump systems with the TES during the summer season was analyzed, and the operational costs with and without the TES were compared. The electric chiller model was used to simulate a heat pump applied without the TES system. Electric rates of each system were measured to calculate operational costs. When the TES is used in the air conditioning system, the electric load (30.4 MWh) calculated in the daytime can move to off-peak load time, and the operational cost is reduced by 36~54%.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.52-57
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• 2009

This paper describes the multi-heat pumps applied in an ground source heat pump system for an actual building. The performance of a ground source multi-heat pump installed in the field was investigated at heating season. The average COP of the systems with single U-tube and double tube type GLHXs were 4.8 and 5.0, respectively. It is needed to investigate the long term performance of double tube type GLHX, because the reduction of inlet temperature of OD HX for this GLHX was larger than it for U-tube GLHX.

• 설비공학논문집
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• 제17권4호
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• pp.341-346
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• 2005

The simplification of solar thermal systems reduces the possibility of operating trouble and lowers the cost of the initial investment and maintenance. This also leads to increased competitiveness in the energy market. We proposed a spiral-jacketed storage tank that functions both as a heat exchanger and expansion tank, which removes the secondary piping and markedly simplifies the entire system. The new storage tank was designed and manufactured to maintain the same performance as the conventional system and the exiting system was remodelled by adopting the newly proposed storage tank. This experiment was conducted under real conditions over a period of several months. The retrofitted system with the spiral-jacketed storage tank showed good performance that is on a similar level as the previous system having a typical storage tank and heat exchanger.

• 설비공학논문집
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• 제18권12호
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• pp.947-954
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• 2006

Building energy consumption according to the ventilation has been considered to be an important subject. The purpose of this study is to investigate the cooling and heating loads in a test space with a forced ventilating system. In the test space, on/off controlled air-conditioning and forced ventilating facility were operated between 8 : 30 to 21 : 00 during 4 days and some important data like temperatures and energy consumption were measured to obtain actual thermal loads. The simulation was carried out in a mode of temperature level control using a TRNSYS 15.3 with a precisely measured air change amount and performance data of air-conditioner. Heating load and cooling load including sensible and latent were compared between by experiment and by simulation. Both of thermal loads associated with ventilation show a close agreement within an engineering tolerance.

• 조명전기설비학회논문지
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• 제21권6호
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• pp.71-76
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• 2007

본 논문에서는 상용전원이 침수되었을 경우, 이에 의한 인체 감전의 위험성을 실증실험을 통해 검토하였다. 실험을 위해 한쪽 벽면에 노출된 충전부가 설치된 모의수조를 구축하고 내부에 도전성 수용액을 채운 후, 전원으로부터의 거리, 방향, 도전성 수용액의 전도율 및 수위에 따른 전위를 측정하였다. 실험 결과 수중에 설치된 전원장치로 인한 전위분포는 거리에 따라 달라지지만, 침수 수용액의 도전율, 노출된 충전부로부터의 각도 및 측정높이는 전기적으로 미치는 영향이 거의 없음이 확인되었다.