• Journal of Advanced Marine Engineering and Technology
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• 제40권2호
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• pp.96-101
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• 2016

The thermal management of high-power LED components in an assembly structure is crucial for the stable operation and proper luminous function. This study employs numerical tools to determine the optimum thermal design in LEDs with a heat sink consisting of a crevice-type vapor-chamber heat pipe. The effects of the MCPCB are investigated in terms of the substrate thicknesses on which the LEDs are mounted. Further, different placement configurations in a system module are considered. This study found that for a confined area, a power of 40 W/LED is applicable to a high-power package. Furthermore, the thermal conductivity of dielectric layer materials should ideally be greater than 0.9 W/m.K. The temperature conditions of the vapor chamber in a heat pipe greatly affect the thermal performance of the system. At an offset distance of 9.0 mm and a $2^{\circ}C$ increase in the temperature of the heat pipe, the resulting maximum temperature increase is approximately $1.9^{\circ}C$ for each heat dissipation temperature. Finally, at a thermal conductivity of 0.3 W/m.K, it was found that the total thermal resistance changes dramatically. Above 1.2 W/m.K, the resistance change reduces exponentially.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제53권8호
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• pp.509-516
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• 2004

The concerns of distributed generations including photovoltaic(PV) system have been increased around the world since PV system is becoming widespread as a clean and gentle energy source for earth. In the future high density grid-connected PV systems will be interconnected with distribution network. As a result, the stability and long-term reliability of PV systems have become more important issues in this area. Grid-connected PV systems have been installed and monitored at field demonstration test center(FDTC) and also data acquisition system(DAS) has been constructed for measuring and analyzing performance of PV system to observe the overall effect of environmental conditions on their operation characteristics. The performance of PV system has been evaluated and analyzed for component perspective (PV array and power conditioning system) and global perspective (system efficiency, capacity factor, and electrical power energy) by field test and loss factors of PV system.

• 설비공학논문집
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• 제20권12호
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• pp.775-780
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• 2008

A dynamic model to simulate LNG reliquefaction process has been developed. The model was applied to two candidate cycles for LNG reliquefaction process, which are Reverse Brayton and Claude cycles. The simulation was intended to simulate the pilot plant under construction for operation of the two cycles and evaluate their feasibility. According to the simulation results, both satisfy control requirements for safe operation of brazed aluminum plate-fin type heat exchangers. In view of energy consumption, the Reverse Brayton cycle is more efficient than the Claude cycle. The latter has an expansion valve in addition to the common facilities sharing with the Reverse Brayton cycle. The expansion valve is a main cause to the efficiency loss. It generates a significant amount of entropy associated with its throttling and increases circulation flow rates of the refrigerant and power consumption caused by its leaking resulting in lowered pressure ratio. It is concluded that the Reverse Brayton cycle is more efficient and simpler in control and construction than the Claude cycle.

• International Journal of Air-Conditioning and Refrigeration
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• 제17권4호
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• pp.135-140
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• 2009

A dynamic model to simulate LNG reliquefaction process has been developed. The model was applied to two candidate cycles for LNG reliquefaction process, which are Reverse Brayton and Claude cycles. The simulation was intended to simulate the pilot plant under construction for operation of the two cycles and evaluate their feasibility. According to the simulation results, both satisfy control requirements for safe operation of brazed aluminum plate-fin type heat exchangers. In view of energy consumption, the Reverse Brayton cycle is more efficient than the Claude cycle. The latter has an expansion valve in addition to the common facilities sharing with the Reverse Brayton cycle. The expansion valve is a main cause to the efficiency loss. It generates a significant amount of entropy associated with its throttling and increases circulation flow rates of the refrigerant and power consumption caused by its leaking resulting in lowered pressure ratio. It is concluded that the Reverse Brayton cycle is more efficient and simpler in control and construction than the Claude cycle.

• 전력전자학회논문지
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• 제16권3호
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• pp.302-308
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• 2011

현재 철도 차량용 공조 시스템은 3상 AC 380V를 입력으로 받아 온/오프 제어만 하고 있어 효율 저감 및 소음 등의 문제점을 가지고 있으며 AC 전원 공급이 차단될 경우 blower 동작이 멈추는 문제점을 가지고 있다. 본 논문에서는 UPS 기능을 갖는 A/C blower용 인버터 시스템을 제안한다. 제안한 인버터 시스템은 입력으로 AC 전원과 DC 전원을 받아서 blower 구동용 유도전동기의 V/F 제어를 하며, CAN통신을 이용하여 속도, 모드 및 Soft-Start 시간 등을 제어한다. 또한 CAN 통신 고장시에는 정비용으로 RS-232통신을 이용해서도 제어할 수 있고 조작자가 직접 하드웨어적으로 제어할 수도 있어 기존의 문제점을 보완할 수 있다. 시뮬레이션과 실험을 통해 제안한 인버터 시스템의 유용성을 입증한다.

• 동력기계공학회지
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• 제19권5호
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• pp.67-72
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• 2015

The reliable operation of onsite emergency diesel generator(EDG) should be ensured by a conditioning monitoring system designed to maintain, monitor and forecast the reliability level of diesel generator. The purpose of this paper is to develop condition diagnosis algorithm(logic) and analysis program of engine for the accurate diagnosis in actual condition of emergency diesel generator engine. As a result of this study, we confirmed that developed engine condition diagnosis algorithm and analysis program could be efficiently applied for actual EDG engine in nuclear power plant.

• 한국태양에너지학회 논문집
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• 제28권5호
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• pp.72-77
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• 2008

The purpose of this paper is to explain the real characteristics of generation system of large scale power system of high voltage the grid connected PV power system for electricity industry. Main system is made up PCS in the class 150kVA. and we studied commercial operation in Korea-Western Power Company,(Tae-An headquarter) with the capacity of module is 122.5 $kW_p$. On the average, power plant utilities' utilization is 12.71 percent and consumption rate is 6.66 percent. We operated normally since 25th, August 2005 without any other problems.

• 전력전자학회논문지
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• 제16권6호
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• pp.587-593
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• 2011

본 논문에서는 고 전력밀도 및 저가형으로 구성 가능한 새로운 구조의 계통 연계형 태양광 인버터 시스템을 제안한다. 제안 시스템은 태양전지의 최대 전력점 추종기능과 배터리의 충 방전 기능을 단일 전력단으로 구성함으로써, 고 전력밀도 및 저가격형 시스템 구성이 가능하다. 또한, 제안 시스템은 배터리를 링크 캐패시터에 직렬 연결함으로써 링크 캐패시터의 전압 스트레스를 배터리 전압만큼 저감할 수 있으므로 가격저감 효과가 크다. 최종적으로 제안 시스템의 우수성과 신뢰성 검증을 위하여 1.5kW급 태양광 인버터 시스템의 시작품을 제작하였고, 이를 이용한 실험결과를 바탕으로 제안 시스템의 타당성을 검증한다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 추계학술대회 초록집
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• pp.49.2-49.2
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• 2011

본 논문에서는 대용량 태양광 PCS의 병렬운전 알고리즘에 대해 제안한다. 제안한 알고리즘은 dc-link 전압을 이용하여 PCS를 독립적으로 제어한다. 일반적으로 태양광 PCS는 정격용량 또는 그 근처에서 최대 효율을 낸다. 제안한 알고리즘은 일사량이 적을 시 일부 PCS만 작동하도록 하여 전력 변환 효율을 높인다. 항상 모든 PCS가 작동하는 것이 아니라 필요한 수량만 작동하도록 하고, 작동하는 PCS도 순차적으로 바꿔서, 전제 시스템의 수명을 늘리는 효과도 있다. 또한 일부 PCS가 고장이 날 경우 다른 PCS가 작동하도록 하여 태양광 발전이 멈추지 않고 계속 발전할 수 있도록 한다.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.1243-1248
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• 2008

$CO_2$ emission amount and characteristics of combined heat and power (CHP) plant in industrial complex of Korea is evaluated by using the fuel analysis method. Fuel analysis methods of several foreign countries and developed one which is developed considering the operation characteristics of the surveyed CHP plants are used. The operation data is surveyed for all of the CHP plants in industrial complex and is composed of fuel consumption amount, generation, sale and efficiency of heat and electricity, condensed steam enthalpy, and etc of the each CHP.