• Journal of Advanced Marine Engineering and Technology
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• 제25권3호
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• pp.573-580
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• 2001

When investigating optimum design of the evaporator in the refrigeration and heat pump systems, there is still lack of data for the dynamic characteristics of the evaporator, This is due to the fact that the static characteristics in the evaporator are absolutely difficult to measure and are burdened with uncertainties. In this study, the simulation works for static characteristics in the evaporator of small air conditioner are carried out to obtain the data of dynamic characteristics. In the simulation, the test evaporator is divided by two-phase evaporating region and single-phase heating region. The major parameters are refrigerant flow rate, heat transfer coefficient of air, air velocity and air temperature. The results show that the calculation method for tube length is an easy-to-use to model analysis of static characteristics and to determine state of refrigerant in the evaporator. The effects of the four parameters on the length of evaporating completed point and heat flow rate to the evaporator are clarified.

• 한국수소및신에너지학회논문집
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• 제28권2호
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• pp.150-155
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• 2017

Proper cooling of PEM fuel cell stack is essential for the high-performance operation of fuel cell system. Insufficient cooling of the stack can cause significant damage to components due to overheating and also can decrease cell performance by dehydration of the polymer electrolyte. In the present study, we performed a computational analysis to assess the condition of the cooling system to secure the proper temperature in fuel cell stack system for high altitude long endurance (HALE) unmanned aerial vehicle (UAV).

• 설비공학논문집
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• 제6권1호
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• pp.54-65
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• 1994

Performance of naturally circulating cooling system of $SF_6$ gas charged transformer was simulated and the variations of gas flow rate, maximum coil temperature, gas temperature and cooling air temperature were investigated with respect to the height of radiator, interplates distance and heat generation rate at core. The results show that the height of radiator most significantly affects the performance of natural circulating cooling system of transformer.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2008년도 추계학술발표대회 논문집
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• pp.263-268
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• 2008

In a residential complex case, the efficiency of land use are maximized, but a variation of external condition such as load in-equality, the increase in wind velocity and solar radiation by a height causes increasing energy in a building. Besides, because of increasing window size for a lighting and a view, it comes heating load in winter and cooling load in summer. A choice of cooling-system is important for this reason. Recently an internal high-rise residential complex installs an air-cooling system and operates individual heating. However, this study applies water-cooling used one public cooling-tower instead of an air-cooling system, also with an efficiency test of an air and a water-cooling system, consider an internal applicability.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2008년도 춘계학술발표대회 개요집
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• pp.29-29
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• 2008

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2003년도 추계학술대회
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• pp.47-52
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• 2003

In the recent years, as the research and the development of micro and precision machinery become active, the interest of micro actuators using SMA(Shape Memory Alloy) has been increased. The dynamic characteristic analysis of SMA is necessary for actuator application and many common researches report the material characteristics of SMA sufficiently. However, the research on dynamic characteristics is very deficient. In this paper, the helical spring are fabricated with NiTi SMA wire of high resistivity. The force, response speed, temperature, and displacement are measured by digital force gauge, infrared thermometer, and laser displacement sensor so that the dynamic characteristics of this SMA is analyzed. Also, bidirectional actuator was fabricated and experimented fir its performance.

• 한국주조공학회지
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• 제17권2호
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• pp.151-157
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• 1997

다섯 조성의 서로 다른 Mo, Ni 및 Mn함량을 지닌 3 mass% C-20 mass% Cr 공정조성의 백주철을 질소분위기하에서, 1173, 1273 및 1373 $^{\circ}K$의 온도로 3.6, 7.2, 14.4 및 28.8 ks동안 불안정화열처리를 행한 후 공냉시켜 잔류오스테나이트를 측정한 결과 합금원소함량, 불안정화열처리조건 및 $V{\Upsilon}$사이에 다음과 같은 관계를 얻었다. 즉 Mo, Ni 및 Mn을 첨가한 결과, 주방상태에서 79.89${\sim}$91.65 vol.%범위의 $V{\Upsilon}$가 얻어 졌으며 퍼얼라이트는 전혀 생성되지 않았다. 1173 $^{\circ}K$에서 불안정화열처리를 한 경우에는 무수히 작은 이차탄화물이 석출하였으나 온도가 높아 질수록 그 수는 점차 감소하여 1373 $^{\circ}K$에서는 거의 관찰되지 않았다. 1173 및 1373 $^{\circ}K$에서 불안정화열처리를 한 경우, 불안정화열처리시간의 증가에 따른 $V{\Upsilon}$의 변화는 미미하였으나 1273 $^{\circ}K$의 경우에는 감소하였다. 또한 Mo, Ni 및 Mn의 첨가량이 많아짐에 따라 $V{\Upsilon}$는 증가하였으며 이 두 함수사이의 관계식을 정립시키기 위하여 P인자를 도입하였다.

• 한국자원리싸이클링학회:학술대회논문집
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• 한국자원리싸이클링학회 2004년도 춘계임시총회 및 제23회 학술대회
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• pp.155-158
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• 2004

본 연구에서는 공냉(空冷)된 화력발전소 바닥재의 입도분포, 화학조성, 광물상 등 기초 특성과 압축강도비에 의해 포졸란 반응성을 측정하였다. 바닥재의 주요 성분은 $SiO_2$, $Al_2O_3,\;Fe_2O_3$로 이들의 합계가 91.2wt.%였으며, 주요 광물상은 mullite, quartz, cristobalite, tridymite, hematie 등이었다. 입도별 화학조성 변동은 거의 없었으나, 입도가 커짐에 따라 $SiO_2$는 quartz에서 cristobalite로 존재하는 비율이 증가하였다. 분쇄된 바닥재(blame 비표면적 $7,540cm^2/g$)의 양생 28일에서의 활성도 지수는 101을 나타내었다.

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2001년도 추계학술대회 논문집
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• pp.99-100
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• 2001

보일러, 소각로 등의 연소공정이나, 금속 용융과정 중에 발생하는 분진은 대부분 여과집진장치에 의해 처리된다. 이러한 연소, 금속용융 공정의 배가스는 매우 고온이기 때문에 공냉식이나 수냉식의 배가스 냉각장치를 거친 후 여과집진장치로 유입된다. 고온 배가스 냉각장치는 집진장치의 설치비를 가중시킬 뿐만 아니라 운전유지비의 상승을 초래한다. 따라서 고온에서도 집진성능을 유지할 수 있는 여과포의 개발이 요구되었고, 국외 유명 여과포 제조업체를 중심으로 고온적용 여과포 개발이 활발히 진행되어 왔다. (중략)

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 2003년도 춘계 학술발표회 논문집
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• pp.351-357
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• 2003

In absorption system, the performance of the absorber is critical the overall system performance, size, and first-cost. The objective of this paper is to provide a comprehensive review of the significant effects that researchers have made to numerically analysis model the coupled heat and mass transfer process that occur during falling-film absorption and experimental researches. This study includes experimental work in the enhancement of absorption performance, the effect of the geometry of a vertical absorber, and the effect of configuration of absorption system. This paper is used to highlight key areas which need attention such as film ans vapor hydrodynamics, especially the non-periodicity, instability, and recirculatory motion of waves in the vertical absorber case.