• Nuclear Engineering and Technology
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• 제56권5호
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• pp.1698-1711
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• 2024

Heat pipe cooled reactors have gained attention as a potential solution for nuclear power generation in space and deep sea applications because of their simple design, scalability, safety and reliability. However, under complex operating conditions, a control strategy for variable load operation is necessary. This paper presents a two-dimensional transient characteristics analysis program for a heat pipe cooled reactor and proposes a variable load control strategy using the recuperator bypass (CSURB). The program was verified against previous studies, and steady-state and step-load operating conditions were calculated. For normal operating condition, the predicted temperature distribution with constant heat pipe temperature boundary conditions agrees well with the literature, with a maximum temperature difference of 0.4 K. With the implementation of the control strategy using the recuperator bypass (CSURB) proposed in this paper, it becomes feasible to achieve variable load operation and return the system to a steady state solely through the self-regulation of the reactor, without the need to operate the control drum. The average temperature difference of the fuel does not exceed 1 % at the four power levels of 70 %,80 %, 90 % and 100 % Full power. The output power of the turbine can match the load change process, and the temperature difference between the inlet and outlet of the turbine increases as the power decreases.

• 한국초전도ㆍ저온공학회논문지
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• 제14권2호
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• pp.20-23
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• 2012

With continuous development of the 2nd generation HTS conductor, the critical current of the conductor is also increasing. However, many applications require more than 2 conductors in parallel to transport large current. Applications such as HTS power cables and some HTS current leads usually need much larger transport current than that provided by a single conductor and they require more than several tens of HTS conductors. In the case of parallel connection of multiple HTS conductors, the current distribution depends on the contact resistance of each conductor at the terminals for DC operation. The non-uniform distribution of the terminal resistances results in a non-uniform distribution of the current. The resultant current non-uniformity affects on the measurement of the I-V curve and the thermal performance of the multiple conductors. This paper describes the I-V curves obtained from multiply connected HTS conductors with different terminal contact resistances to investigate the relationship between the distorted I-V curve and heat generation.

• 반도체디스플레이기술학회지
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• 제19권1호
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• pp.42-48
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• 2020

As global warming accelerates, eco-friendly electric cars are being developed to reduce carbon dioxide emissions, and power conversion inverters are used to drive motors. Among inverter components, DC-link capacitor is heated by high current usage, which causes problems such as performance and life-saving of inverter. Although metal cases with good thermal performance have been used to solve this problem, it is difficult to apply them in practice due to insulation problems with other parts. In this paper, the Heat-Generation influence factor of DC-link capacitor is analyzed. Variables on heat-generation are set at 3 levels for film width, inductance, and film thickness. Box-Behnken to 13 tests using the design and minimal deviations, e.g. through the experiment three times by each level. The surface of the film k type by attaching the sensor current is measured temperature. Capacitance was set to a minimum level of 200 ㎌ and had a frequency of 16 kHz with Worst case, ambient temperature of 85℃ and a ripple current of 50 Ams was applied. The temperature at the measurement point was collected in the data logger after sampling at 1 minute intervals for 2 hours after saturation with the ambient temperature. This experiment confirmed that setup factors are correlated with heat-generation.

• 환경영향평가
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• 제27권3호
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• pp.322-333
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• 2018

본 연구는 환경영향평가 제도 운영의 성과를 정량적으로 분석하기 위하여 화력발전소 대기질 분야에서 환경영향평가를 통한 환경영향 저감효과를 계량화하고 그로 인한 사회적 편익을 추정하였다. 환경영향평가의 성과는 제도의 시행여부에 따른 차이로 정의하고, 개별 사업이 환경영향평가를 시행하지 않더라도 준수해야하는 환경 관련 기준과 환경영향평가를 통해 협의된 협의기준을 비교하였다. 2010년부터 10년간 협의완료된 화력발전소 건설사업 전체 60건을 대상으로 환경영향평가의 시행여부에 따른 차이를 추정한 결과 주요 대기오염물질의 배출량이 크게 저감된 것으로 나타났다. $PM_{10}$의 경우 연간 3,745톤, $NO_2$는 74,569톤, $SO_2$는 37,647톤의 배출량이 저감되었으며, 이를 사회적 편익으로 환산한 결과 방법론에 따라 연간 2,397억 원에서 5조 9,665억 원으로 추정되었고, 이는 화력발전소의 운영기간 30년 동안 7조 1,916억 원에서 178조 9,944억 원에 이르는 규모의 사회적 비용이 절감되는 것을 의미한다. 저감된 대기오염물질의 배출량의 규모는 전국의 에너지 발전시설에서 배출되는 양의 절반에 이르며, 우리나라의 연간 경상의료비보다 큰 금액의 경제적 가치를 지닌다. 이는 모든 사업이 배출허용기준과 같이 관련 근거법에 따라서 획일적인 기준을 적용받지만, 환경영향평가 과정을 통해 대상 지역과 사업의 특성 등을 고려하여 각각의 사업계획이 수립됨에 따라 발생한 성과임을 의미한다.

• 한국산학기술학회논문지
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• 제20권4호
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• pp.580-589
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• 2019

인도네시아는 전력 공급이 매우 부족한 현실에 처해 있으며, 이에 대한 해결책으로 화력발전소 건설 계획이 증가하고 있다. 화력발전소는 발전에 수반되는 엔진과 장비의 과열을 식히기 위해 냉각수 계통을 필요로 하며, 냉각수 계통 중 순환수 취수펌프장(circulating water pump chamber)은 일반적으로 ANSI (1998) 기준에 따라 설계된다. 본 연구에서는 인도네시아 K-석탄화력발전소의 순환수취수펌프장이 현장 여건상 ANSI (1998)의 확산각 설계기준 $20^{\circ}$를 만족시킬 수 없어, 수리적으로 안정된 흐름 및 구조물이 되도록 3차원 수치모형실험을 수행하였다. 수치모형으로 Flow-3D 모형을 이용하였다. Flow-3D 모형의 적용성을 검토하기 위해 Rodi (1997)의 사각형 구조물 주변에 형성되는 흐름 연구 결과와 금회 수치해석 결과를 비교하였다. 수치해석에서 도출된 종방향 유속 분포는 잘 일치함을 보여주고 있다. 순환수취수펌프장 내 설계유속을 만족시키기 위해 유속 저감에 유리한 사각형 형태의 배플을 적용하였다. 순환수취수펌프장으로 유입되는 유속이 1.5 m/s ~ 2.5 m/s로 분포되는 경우, 배플에서 분리흐름의 각도는 약 $15^{\circ}{\sim}20^{\circ}$로 발생하였다. 이를 고려하여 분리흐름 각도 이하로 하류에 배플을 배치함으로 Inlet bay 설계유속 0.5 m/s 이하를 만족시켰다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 춘계학술대회
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• pp.668-671
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• 2007

A numerical study was conducted on a simplified model of a high-temperature solar receiver which incorporates liquid-metal heat pipe. The objective of this paper is to compare the isothermal characteristics of the heat pipe receiver with the conventional receiver utilizing convection of molten salt as heat carrier. The solar receiver was assumed to be subject to a concentration ratio between 50 and 1,000 to supply high-temperature heat to a stirling engine for electric power generation. For simplicity of the analysis, a cylindrical geometry was assumed and typical dimensions were used based on available literature. The heat pipe had a shape of double-walled cavity and the working fluid was a sodium. The analysis was performed assuming that the radiation heat flux on the inner walls of the receiver was uniform, since the focus of this study was laid on the comparison of the conventional type and heat pipe type receiver. The results showed that the heat pipe type exhibited superior performance when the operating temperature becomes higher. In addition, to explore the advantage of the heat pipe receiver, the channel shape and dimensions should be adjusted to increase the heat transfer area between the wall and the heat trnasfer medium.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2008년도 추계학술발표대회 논문집
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• pp.232-237
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• 2008

The integration of PV modules into building facades or roof could raise their temperature that results in the reduction of PV system's electrical power generation. Hot air can be extracted from the space between PV modules and building envelope, and used for heating in buildings. The extraction of hot air from the space will enhance the performance of BIPV systems. The solar collector utilizing these two aspects is called PV/T(photovoltaic/thermal) solar collector. This research is about the development of solar roof system with PV/T collector to apply into buildings. A test cell experiment was performed with the PVT roof installed: It found that the hot air supply from the PVT air collector contributed to increase the heating efficiency by 2 times and the electrical efficiency by about 8%.

• 한국전기전자재료학회논문지
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• 제29권12호
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• pp.819-823
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• 2016

DSSC (dye-sensitized solar cell) is expected to be one of the next-generation photovoltaics because of its environment-friendly and low-cost properties. However, commercialization of DSSC is difficult because of the electrolyte leakage. We propose thermal curable base on silicon resin and apply a unit cell and large area ($200{\times}200mm$) dye-sensitized solar cell. The resin aimed at sealing of DSSC and gives a promising resolution for sealing of practical DSSC. In result, the photoelectric conversion efficiency of the unit cell and the module was 6.63% and 5.49%, respectively. In the durability test result, the photoelectric conversion efficiency of the module during 500, 1,000, 1,500 and 2,000 hours was 0.73%, 0.73%, 1.82% and 2.36% respectively. It was confirmed that the photoelectric conversion efficiency characteristics are constant. We have developed encapsulation material of thermal curing method excellent in chemical resistance. A sealing material was applied to the dye-sensitized solar cell and it solved the problem of durability the dye-sensitized solar cell. Sealing material may be applied to verify the possibility of practical application of the dye-sensitized solar cell.

• Nuclear Engineering and Technology
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• 제54권1호
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• pp.72-83
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• 2022

This paper presents a numerical investigation of two-phase natural circulation flows established when external reactor vessel cooling is applied to a severe accident of the APR1400 reactor for the in-vessel retention of the core melt. The coolability limit due to external reactor vessel cooling is associated with the natural circulation flow rate around the lower head of the reactor vessel. For an elaborate prediction of the natural circulation flow rate using a thermal-hydraulic system code, MARS-KS1.5, a three-dimensional computational fluid dynamics (CFD) simulation is conducted to estimate the flow rate and pressure distribution of a liquid-state coolant at the brink of significant void generation. The CFD calculation results are used to determine the loss coefficient at major flow junctions, where substantial pressure losses are expected, in the nodalization scheme of the MARS-KS code such that the single-phase flow rate is the same as that predicted via CFD simulations. Subsequently, the MARS-KS analysis is performed for the two-phase natural circulation regime, and the transient behavior of the main thermal-hydraulic variables is investigated.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 B
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• pp.1332-1334
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• 2002

Thermoelectric generation is the direct energy conversion method from heat th electric power. The conversion method is a very useful utilization of waste energy because of its possibility using a thermal energy below $150^{\circ}C$ This research objective is th establish the thermoelectric technology on a optimum system design method and efficiency, and cost effective thermoelectric element in order to extract the maximum electric power from a wasted hot water. This paper is considered in manufacturing a thermoelectric generator and measuring of electric resistance of module a thermoelectric modules. It was found that the electric resistance of thermoelectric modules was defined as a temperature functions. The relationship between electric resistance and temperature characteristics can be a analogized as function of electric current.