• 한국태양에너지학회 논문집
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• 제34권1호
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• pp.58-63
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• 2014

A vertical closed loop ground source heat pump (GSHP) is used to produce heat from the low-grade energy source such as the outside air and ground source. It is known that a heat pump system type has better efficiency comparing to the electric heating system. This study only demonstrates that the vertical closed loop GSHP system is a feasible choice for space cooling of air conditioning. The coefficient of performance (COP) is the ratio of heat output to work supplied to the system in the form of electricity. For the vertical closed loop GSHP system in a cooling mode, the COP is the most commonly used way for judging the efficiency. For the purpose of this experiment, vertical closed loop GSHP system was installed in the laboratory and the experiment was executed. As a result, an average COP of vertical-closed loop GSHP system was 3.62 when the outside average temperature was $33^{\circ}C$.

• 한국태양에너지학회 논문집
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• 제31권5호
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• pp.67-76
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• 2011

생활공간 냉난방용 열펌프의 성능향상을 위해 R22의 대체 냉매로서 새로운 혼합냉매R22/R23/R152a(RM-1)을 개발하고 U. S. A.의 NIST사의 REFPRO Pprogram을 이용해 이 혼합냉매의 P-h diagram을 구성하여 실용화에 이용할 수 있도록 하였다. 본 연구는 실험을 통해 R22와 RM-1의 열펌프 성능효과를 분석하였다. 입 출구 물의 온도와 제2의 전열매체로서 물의 질량유량, 압축기의 소요 에너지 그리고 열펌프의 기타 열적 특성을 다양한 조건하에서 측정하였다. 이 실험 데이터를 통해 공기-물 열펌프 시스템에서의 RM-1과 R22의 성능계수(COP)를 비교하였다. 이를 통해, 혼합냉매 RM-1을 사용하는 열펌프 시스템은 외기온 $-17^{\circ}C$에서도 2.2의 성능계수로 작동하는 결과를 본 연구에서 보여주었다.

• 설비공학논문집
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• 제13권9호
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• pp.904-913
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• 2001

The objective of this study was to investigate the characteristics of jet flow and heat transfer caused by trapezoid rods array in impinging jet system. In this study, trapezoid rods have been set up in front of flat plate to serve as a turbulence promoter. The bottom width of trapezoid rod was W=4, 8 mm and oblique angle were 80$^{\circ}$. The space from rods to the heating surface was C=1, 2, 4 mm, the pitch between each rods was P=30, 40, 50 mm, and the distance from nozzle exit to flat plate was H=100, 500 mm. This results were compared with the case without trapezoid rods. As a result, when rods are installed in front of the impinging plate, the acceleration of the jet flow and the eddies due to the rods seem to contribute to the heat transfer enhancement. Among test conditions, the heat transfer performance was best for the condition of W=8 mm, C=1 mm, P=30 mm and H/B=10. The maximum heat transfer rate is about 1.9 times larger than that without trapezoid rods.

• 설비공학논문집
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• 제21권5호
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• pp.267-272
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• 2009

This study aims to investigate and analyze the present state of ground source heat pump(GSHP) system applied in Korea. It is based on the statistic from the New and Renewable Energy Center in Korea and construction results of the professional companies registered to the center. The research items were installed area, installed year, building use, ground heat exchange type and heat exchanger type of the pump. According to the result of investigation, the using GSHP system have been increasing steadily as the space heating and cooling system in a building. The capacity of this system is also becoming lager based on technical and economical feasibility analysis about the system since GSHP system first introduced in 2000.

• 천문학회보
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• 제39권1호
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• pp.67.2-67.2
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• 2014

Comet nucleus is a solid body consisting of dark dust grains and ice. Cometary volatiles sublimate from subsurface layer by solar heating, leaving behind large dust grains on the surface. Eventually, the appearance could turn into asteroidal rather than cometary. It is, therefore, expected that there would be "dormant comets" in the list of known asteroids. Our research group has undertaken the research on the population of dormant comets. We applied a brand-new asteroidal catalog compiled from data garnered by three infrared astronomical observatories, AKARI, IRAS and WISE. We extracted objects which have comet-like orbits on the basis of their orbital properties (Tisserand parameters with respect to Jupiter, TJ, and aphelion distance, Q). We found that (1) there are a considerable number (>100) of asteroids in comet-like orbits, and (2) 80% of them have low albedo consistent with comets. This result suggest that these low albedo objects could be dormant comets. One unanticipated finding is that 20% of asteroids in comet-like orbit have high albedo similar to S-type asteroids. It is difficult to explain the population of S-type asteroids in comet-like orbits by the classical mechanics theory. We further found that these high-albedo objects are small (D < 2 km) bodies distributed in near-Earth space. We suggest that such high-albedo, small, near-Earth asteroids are susceptible to Yarkovsky effect and injected into comet-like orbits.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 추계학술대회 논문집 전기물성,응용부문
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• pp.220-221
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• 2006

In recent, there have been several developments in lamp technology that promise savings in electrical power consumption and improved Quality of the lighting space. Above all, the advantages of ring-shaped electrodeless fluorescent lamp are the removal of internal electrodes and heating filaments that are a light-limiting factor of conventional fluorescent lamps. Therefore, the life time of ring-shaped electrodeless fluorescent lamps is substantially higher than that of conventional fluorescent lamps last up to 60,000 hours, There are intended as a highly efficient replacement for the incandescent reflector lamp in many applications. In this paper, maxwell 3D finite element analysis program (Ansoft) was used to obtain electromagnetic properties associated with the coil and nearby structures. The electromagnetic emitting properties were presented by 3D simulation software operated at 250 kHz and some specific conditions. In addition, the optical characteristics of ring-shaped electrodeless fluorescent lamp were measured including light flux, efficiency and color temperature for each case.

• Advances in Energy Research
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• 제6권2호
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• pp.161-172
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• 2019

The principal intention of this experimental work is to confer upon the exergy study of GSHP associated with horizontal earth heat exchanger for space heating. The exergy analysis recognizes the assessment of the tendency of various energy flows and quantifies the extensive impression of inefficiencies in the system and its components. Consequently, this study intends to provide the enlightenment for well interpretation of exergy concept for GSHP. This GSHP system is composed of heat pump cycle, earth heat exchanger cycle and fan coil cycle. All the required data were measured and recorded when the experimental set up run at steady state and average of the measured data were used for exergy investigation purpose. In this study the rate at which exergy destructed at all the subsystems and system has been estimated using the analytical expression. The overall rational exergetic efficiency of the GSHP system was evaluated for estimating its effectiveness. Hence, we draw the exergy flow diagram by using the various calculated results. The result shows that in the whole system the maximum exergy destruction rate component was compressor and minimum exergy flow component was earth heat exchanger. Consequently, compressor and earth heat exchanger need to be pay more attention.

• 설비공학논문집
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• 제18권7호
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• pp.541-548
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• 2006

A hybrid ventilation system was introduced to predict the ventilation performance of the apartments. This ventilation system was composed of the natural supply-air inlet and the forced exhaust-air outlet. Analysis was conducted by CFD technique and was performed on three ventilating flow rates; 30, 60, $120m^3/h$. As the results, residents feel comfortable thermally for $60m^3/h$. In the case of $120m^3/h$, however, residents feel uncomfortable both thermally and in air currents. In this study the energy saving for space heating is also an important factor. In the case of whole region with $180m^3/h$, residents feel comfortable at each region of the model apartment. It is shown that this hybrid ventilation system is possible method for the apartment house.

• 설비공학논문집
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• 제18권7호
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• pp.571-577
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• 2006

The characteristics of ice packing factor (IPF) at the ice slurry system using one line type are compared with the system using two lines type. The installation space for one transporting line is saved at the one line system. For the one line type, the ice packing factor is reduced along the downstream, but for the two lines type, the ice packing factor is fixed. For the one line system, mass flow rate in the main line is fixed along the down-stream, but for two lines system, the mass flow rate in the main line is reduced along the downstream. For one line system, along the down stream after IPF=0, the temperature at the main steam is increased, and the extracted mass flow is increased. The initial IPF, at which the IPF is not arrived at zero upto the final node, is proposed for the B area.

• 한국주거학회:학술대회논문집
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• 한국주거학회 2002년도 추계학술발표대회
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• pp.249-254
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• 2002

The purpose of this study is to identify the causes-effects of residential mobility and satisfaction. The research design employes a survey questionnaire for gathering a set of statistically-reasonable number of data among one million population of Ulsan metropolitan city. To make it more concrete, the attentions to be taken are on establishing (1) motives for moving (2) satisfaction factors in living, and (3) a relationship between houses and their environmental characteristics and the degree of satisfactions by them. The results of empirical analyses provide the following major findings: The most significant house-moving motivations were to achieve living-space at an affordable size or as wide as possible and to gain access to a comfortable and convenient environment. Per the residential satisfaction, highly respected factors were having good neighbors and active interactions with them and having good cooling-heating conditions, sunny rooms, and less noise and air pollution. Finally, the relation of house and its environment with the satisfaction indicated the following significant two: The higher the satisfaction, the shorter the duration of living and the history of construction. The less the satisfaction, the smaller the size of house and/or its complex.