• 한국자동차공학회논문집
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• 제11권5호
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• pp.70-76
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• 2003

An experimental study was performed to understand the heat transfer and fluid dynamic characteristics of Sub-Cooled Hybrid Condenser (SCHC), which conventional condenser and receiver dryer are integrated into. SCHC also employs a sub-cooled refrigerant passages at the end of the condenser in order to supply perfect liquid refrigerant to the expansion unit. Throughout the present study, it was found that the developed SCHC increases in the degree of sub-cooling by 10~100% compared to conventional condenser. The excessive sub-cooling has improved the cooling performance by 10%, and that leads reduction in evaporator outlet air temperature by $1.5^{\circ}C$. Also found through the study is that the refrigerant pressure drop across SCHC is fairly increased due to insertion of the desiccant cartridge in the receiver tank which is composed of zeolite, filter and supporter plate.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.990-995
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• 2009

Experimental basic study was performed to understand the characteristics of sub-cooled refrigerant using a cold heat storage system. This system was made up general vapor-compression refrigeration cycle added sub-cooler and ice storage tank. The purpose of this study are to application use of cold-heat storage systems multiplicity of fields and to understand of sub-cooling system. At the condition using ice storage system, the ice making process was operated during night time by electric power. And then, the refrigerant was sub-cooled using stored cold-heat after being discharged from the air cooling condenser during the day time. Comparing the result at general operation with the operation using sub-cooling system. This study showed the effects of the sub-cooled degree. The cooling performance was increased owing to the sub-cooling of refrigerant during day time, and the compressor consume power was a little decreased. Thus the COP was also increased owing to the sub-cooling of refrigerant.

• 한국태양에너지학회 논문집
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• 제28권1호
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• pp.65-74
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• 2008

In this study, dynamic characteristics analysis of AC system is investigated using a cool thermal storage system. A analysing program for cool thermal storage AC system is developed. The performances are studied by several variables and dynamic characteristics. Comparing the result at conventional operation condition with that at the condition using ice storage system, this study showed the effects of the sub cooled degree, superheated degree, efficiency of compressor and evaporating temperature. At the condition using thermal storage system, the thermal storage process was operated during midnight being not needed the cooling of the AC unit through the continuous running of the condenser. The refrigerant was sub-cooled using stored energy after being discharged from the air source condenser during the daytime. The COP was increased owing to the sub-cooling of refrigerant during daytime, thus the power consumption was effectively decreased.

• 한국자동차공학회논문집
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• 제12권5호
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• pp.205-210
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• 2004

Sub-cooled hybrid condenser(SCHC) which have been developed through this study is an appliance of integrating a condenser with a receiver dryer, which were previously separated. It is supposed that the development of sub-cooled hybrid condenser will be able to reduce not only weight, size, production process and cost, but also quite improve in capability, which will be of great use for the technological development and research of an air conditioning system whose importance is higher in a car. Through the present study it was found that the developed SCHC increases in the degree of sub-cooling by 10∼100% compared to conventional condenser. The excessive sub-cool has improved the cooling performance by 10%, and that leads to the reduction in evaporator outlet air temperature $1.5^{\circ}C$. Additionally, it is expected that sub-cooled hybrid condenser weights less by 100g than the previous condensers which has equal super heat.

• 대한설비공학회지:설비저널
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• 제17권4호
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• pp.408-417
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• 1988

This study optimized the condenser dimension of heat pump system with the heat sources which are solar irradiation and ambient air. At first, the author selected the principal design factors influencing the performance of heat pump system. And the author considered the variation of condenser dimension according to the variation of the selected design factors, that is, ambient air temperature, condenser temperature, degree of superheating, degree of sub-cooling and irradiation. As a result this study, among refrigerants R12, R22 and R500, refrigerant R22 has more heating output than R12 and R500, and the coefficient of performance on this heat pump system is not greatly influenced by the degree of superheating and degree of sub cooling. The ambient air temperature is below $5^{\circ}C$ at balance point and the optimal tube length of condenser dimension is about 3.8 m. Also the author gained the optimal design diagram for the optimization of condenser dimension according to various design factors.

• 한국태양에너지학회 논문집
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• 제38권6호
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• pp.15-26
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• 2018

It is difficult to check the exact building energy consumption reduction such as when green remodeling of buildings, because it is due to outdoor air temperature over the years. And in Korea although Big Data of building energy consumption is collected and managed through "The Information System of the Building Energy and Greenhouse Gases" it is underutilized because of non calibration of outdoor air temperature change. Therefore, this study aims to develope calibration method of building energy consumption by outdoor air temperature according to micro climates, and building use types. As a result of analysis, Regression equations of Building energy consumption and $HDD_m/CDD_m$ are derived and calibration method is developed by Regression coefficient.

• 한국기계가공학회지
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• 제13권5호
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• pp.43-49
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• 2014

This study was carried out to improve the design of an intercooler for a small marine diesel engine. Diesel engines for small marine ships have mainly been developed by changing the structure of the vehicle engine. Sea water was most commonly used in the intercooler of small marine diesel engines to cool the hot air compressed by the turbocharger. In this study, the intercooler is modeled and simulated using STAR-CCM+ in order to find optimal data for the design of an intercooler. In the results, the temperature differences between the data from a numerical analysis and experimental data were $0.38^{\circ}C$ in the hot air outlet and $3.63^{\circ}C$ in the cooling water outlet. Therefore, it was confirmed that both analysis and experimental results need to be considered when designing an intercooler. A closer degree of similarity in the two datasets can improve the confidence in the design of these intercoolers.

• Restorative Dentistry and Endodontics
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• 제21권2호
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• pp.451-469
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• 1996

The purpose of this study was to investigate the effect of calcium hydroxide and glass ionomer cement fillings on the levels of $LTB_4$ and $LTC_4$ in experimentally inflamed rat dental pulp. The dental pulp in the mandibular incisor of wistar rat was irritated by cutting a 5mm deep hole in the dentin with a twist drill bur of 0.5mm diameter, without cooling. The cavities were filled with calcium hydroxide(light-cured) and glass ionomer cement(light cured). The untreated pulp served as control tissue specimen. After cavity preparations, the rat with or without various treatment were sacrificed in various time by decapitation. The dental pulp tissue were carefully removed and the concentrations of $LTB_4$ and $LTC_4$ were determined by radioimmunoassay. And pulps were examined histologically to observe inflammatory feature. The result were obtained as follows : 1. The inflammatory features of pulps were observed microscopically in all experimental groups. And degree of inflammation was decreased with time. 2. The concentrations of $LTB_4$ and $LTC_4$ for all experimental groups were significantly higher than those for control group 6 hours after cavity preparation(p<0.05). 3. The group filled with calcium hydroxide was the lowest, and the group filled with glass ionomer cement, the group of irritation in that order showed increased concentrations of $LTB_4$ and $LTC_4$ 6 hours after cavity preparation. In the concentrations of $LTB_4$, significant differences among 3 groups were noted(p<0.05). 4. The group filled with calcium hydroxide was the lowest, and the group filled with glass ionomer cement, the group of irritation in that order showed increased concentrations of $LTB_4$ and $LTC_4$ 24 hours after cavity preparation. And there were statistically significant difference in concentrations of $LTB_4$ between the group of irritation and the group filled with calcium hydroxide(p<0.05). 5. The group filled with calcium hydroxide was the lowest, and the group filled with glass ionomer cement, the group of irritation in that order showed increased concentrations of $LTB_4$ and $LTC_4$ 48 hours after cavity preparation. But no statistically difference was found (p>0.05). 6. The concentrations of $LTB_4$ and $LTC_4$ in all experimental groups were highest level at 6 hour after experiment and decreased as time progresses(correlation coefficient>0.8).

• Journal of Advanced Marine Engineering and Technology
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• 제38권9호
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• pp.1021-1026
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• 2014

본 논문에서는 hot-gas를 이용한 다양한 바이패스 제어 방식 중에서 증발기 흡입부 방식에 대해 각각의 성능에 영향을 미치는 외기온도, 출수온도, 과열 및 과냉도 등에 대해서 알아보았다. 그 주요 결과를 요약하면 다음과 같다. 우선, 증발기 흡입부로 hot-gas를 바이패스 하였을 경우에 냉동장치의 성능은 외기온도, 출수온도, 과열 및 과냉도 등에 영향을 받는 것을 알 수 있었다. 따라서 이러한 변수에 대한 최적화를 통해 본 냉동장치의 기초 설계 자료를 제공할 수 있다. 그리고 증발기 흡입부 hot-gas 바이패스 방식의 운전특성을 고찰하여 본 논문에서 제안하는 냉동장치에 대한 적용 가능성을 확인할 수 있었다.

• 천문학회보
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• 제46권2호
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• pp.45.1-45.1
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• 2021

Horizon Run 5 (HR5) is a cosmological hydrodynamical simulation which captures the properties of the Universe on aGpc scale while achieving a resolution of 1kpc. This enormous dynamic range allows us to simultaneously capture the physics of the cosmic web on very large scales and account for the formation and evolution of dwarf galaxies on much smaller scales. On the back of a remarkable achievement of this, we have finished to run follow-up simulations which have 2 times larger volume than before and are expected to complementary to some limitations of previous HR simulations both for the study on the large scale features and the expansion history in a distant Universe. For these simulations, we consider the sub-grid physics of radiative heating/cooling, reionization, star formation, SN/AGN feedbacks, chemical evolution and the growth of super-massive blackholes. In order to do this project, we implemented a hybrid MPI-OpenMP version of the RAMSES code, 'RAMSES-OMP', which is specifically designed for modern many-core many thread parallel systems. These simulation successfully reproduce various observation result and provide a large amount of statistical samples of Lyman-alpha emitters and protoclusters which are important to understand the formation and expansion history of early universe. These are invaluable assets for the interpretation of current ΛCDM cosmology and current/upcoming deep surveys of the Universe, such as the world largest narrow band imaging survey, ODIN (One-hundred-square-degree Dark energy camera Imaging in Narrow band).