• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.433-437
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• 2005

This study was carried out the design and analysis of solar thermal system with preheating of returning district heating water for the Chung-ju district heating and cooling system. Two different types of solar collectors are used for this system. TRNSYS simulation program was used for the analysis. As a results, the solar system efficiency is $35.8\%$ for the plate type and $45.1\%$ for the evacuated type solar collector in the case of $50^{\circ}C$ for the returning district heating water temperature. The returning district heating water temperature is on of the very important factors that is influence on the system efficiency. So the effect of the returning district heating water temperature on the system efficiency is analyzed in this study.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.178-181
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• 2008

Cylindrical stainless-steel/sodium heat pipe for a high-temperature application was manufactured and tested for transient and steady-state operations. The container material was made of stainless-steel 316, and the working fluid was sodium. Stainless-steel 316 mesh screen was inserted as a capillary structure. The working fluid fill charge ratio was approximately 64 $\sim$ 181% based on the pore space of the wick. The outer diameter of the heat pipe was 12.7 mm and the total length was 250 mm. The evaporator part was 150 mm and the condenser 80 mm. The performance test of the heat pipe has been conducted in the furnace with up to 800 W. The variation of the average heat transfer coefficient was investigated as a function of heat flux and vapor temperature. As input thermal load increased, it was showed that difference of temperatures in evaporator and condenser decreased and that operating section and heat transfer characteristics at the heat pipe increased.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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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.

• New & Renewable Energy
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• v.1 no.2 s.2
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• pp.53-59
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• 2005

Objective of the research is to demonstrate solar thermal space and ground heating system which is integrated to a green-house culture facility for reducing healing cost, Increasing the value of product by environment control, and developing advanced culture technology by deploying solar thermal system. Field test for the demonstration was carried out in horticulture complex In Jeju Island. Medium scale solar hot water system was installed in a ground heating culture facility. Reliability and economic aspect of the system which was operated complementary with thermal storage and solar hot water generation were analyzed by investigating collector efficiency, operation performance, and control features. Short term day test on element performance and Long term test of the whole system were carried out. Optimum operating condition and its characteristics were closely Investigated by changing the control condition based on the temperature difference which Is the most important operating parameter For establishing more reliable and optimal design data regarding system scale and operation condition, continuous operation and monitoring on the system need to be further carried out. However, It is expected that, in high-insolation areas where large-scale ground storage is adaptable, solar system demonstrated in the research could be economically competitive and promisingly disseminate over various application areas.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.161-164
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• 2006

A design program has been developed to predict film cooling performance in a liquid rocket engine combustion chamber. A thermal protecting effect of low mixture ratio gas has been analysed by CFD. A one-dimensional film cooling model based on the CFD results has been implemented in the previously developed design program of regenerative cooling. The predicted heat flux at the nozzle throat ranges from -16% to +28% when it is compared to the published measured data. The throat heat flux reduces by 36% when film cooling of 10% of fuel mass flow rate is applied.

• Journal of the Korean Society of Propulsion Engineers
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• v.10 no.4
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• pp.85-92
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• 2006

A design program has been developed to predict film cooling performance of a liquid rocket engine. A thermal protecting effect of low mixture ratio gas layer has been analysed by CFD. A one-dimensional film cooling model based on the CFD results has been implemented to the previously developed design program of regenerative cooling. Satisfactory agreement has been achieved by comparing the predicted maximum heat flux at the throat of a subscale chamber and the average measured value, and the predicted nozzle average heat flux and the measured value for a full scale chamber with film cooling. It is ascertained that the film cooling is effective to reduce the throat heat flux in rocket engine chamber.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.4
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• pp.455-459
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• 2010

In recent years, the crisis of energy is growing seriously and also the contamination of ecology has been reverberated as international problem. The social concerns on energy crisis have been growing for the last several years and also the interests in new and renewable energy have been increased. Therefore, in order to solving these problems, this study has dealt with the solar air collector with perforated endothermic panel to increase the indoor temperature. And also, the PV panel for running indoor air circulating fan has used to increase the convective heat transfer. From this study, the inlet air temperature is increased up to 42[$^{\circ}C$]. This temperature is enough to heat the indoor air condition during winter season. And also the result revealed that the mixing effect of convection is increased with increasing in fan circulating power.

• Aerospace Engineering and Technology
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• v.3 no.1
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• pp.197-204
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• 2004

A design of regenerative cooling system of 30 ton level thrust combustion chamber for ground test has been performed. The 1-D design code has been validated by comparing with the heat flux of the NAL calorimeter for high chamber pressure and water-cooling performance of the ECC engine of MOBIS. The present design code has been confirmed to predict accurately the heat flux and water-cooling performance for high chamber pressure condition. The maximum hot-gas-side wall temperature is predicted to be about 720 K without thermal barrier coating and the coolant-side wall temperature is less than the coking temperature of RP-1. The coolant temperature rises nearly 100 K with thermal barrier coating when Jet-A1 is used as coolant.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.474-477
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• 2006

유동형 급속열분해기((fluidized bed type fast pyrolyzer, 용량 300g/h)를 이용하여 너도밤나무와 침엽수 흔합재(독일가문비나무/전나무, 50:50)로부터 바이오오일을 생산하였다. 목질바이오매스의 열분해는 약 $470{\pm}5^{\circ}C$에서 1-2초 간 진행되었다. 목질바이오매스의 열분해 생성물의 조성을 살펴보면, 너도밤나무는 바이오오일이 약 60%, 탄이 약 9% 피리 고 가스가 31% 가량 생산되었으며, 침엽수 혼합재는 49%의 바이오오일, 9%의 탄, 그리고 42% 가량의 가스가 생성되었다. 두 종류의 목질바이오매스에서 생산된 바이오오일에는 약 17-22% 가량의 수분이 포함되어 있었으며, 비중은 약 1.2kg/L 이었다. 바이오오일의 원소 조성은 탄소가 45%, 산소가 47% 수소가 7%, 그리 고 질소가 1% 로서 일반적 인 목질바이오매스와 큰 차이는 없는 것으로 나타났다. 그러나 화석자원에서 생산되는 오일류와 비교하여 산소함량은 매우 높았으나 황은 전혀 포함하고 있지 않았다. 바이오오일의 GC분석 결과 총 90여종의 고리형, 또는 비고리형 저분자량 화합물이 검출되었으며 이들의 함량은 바이오오일 전건중량의 31-33% 정도로 측정되었다.

• New & Renewable Energy
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• v.19 no.3
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• pp.22-33
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• 2023

The number of fire and explosion accidents caused by pyrolysis oil and gas at waste plastic pyrolysis plants is increasing, but accident status and safety conditions have not been clearly identified. Therefore, the aim of the study was to identify the risks of the waste plastic pyrolysis process and suggest appropriate safety management measures. We collected information on 19 cases of fire and explosion accidents that occurred between 2010 and 2021 at 26 waste plastic pyrolysis plants using the Korea Occupational Safety and Health Agency (KOSHA) database and media reports. The mechanical, managerial, personnel-related, and environmental problems within a plant and problems related to government agencies and the design, manufacturing, and installation companies involved with pyrolysis equipment were analyzed using the 4Ms of Machines, Management, Man, and Media, as well as the System-Theoretic Accident Model and Processes (STAMP) methodology for seven accident cases with accident investigation reports. Study findings indicate the need for establishing legal and institutional support measures for waste plastic pyrolysis plants in order to prevent fire and explosion accidents in the pyrolysis process. In addition, ensuring safety from the design and manufacturing stages of facilities is essential, as are measures that ensure systematic operations after the installation of safety devices.