• Journal of Biosystems Engineering
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• 제28권3호
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• pp.217-224
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• 2003

To find out heating load and to determine the power of heat pump compressor for the Ondol room heating the COP of heat pump, the variation of Ondol room air temperature, the variation of ambient temperature and power consumption of heat pump are analyzed. The results from this study were summarized as follows: 1. The COP of the heat pump in close loop decreased as the ambient air temperature. The COP was 2.26 when the temperature difference of condenser was $20\pm3^{\circ}C$. 2. The Ondol surface temperature was $25\pm3^{\circ}C$ when the hot water of $40^{\circ}C$ was supplied from hot water storage tank to the Ondol and the temperature difference between the Ondol surface and the room air temperature was $7~8^{\circ}C$. 3. The ratio of thermal conduction heating load to total heating load in Ondol heating space was found to be 83% and ratio of ventilation heating load was 17%. Therefore, the thermal conduction heating load was confirmod to be a major heating load in Ondol heating space. 4. In case of the ambient temperature of $3.2^{\circ}C$, the efficiency of heat exchange of Ondol heating system was 85%. 5. The heating load per Ondol heating surface area and volume of Ondol room space were theoretically analyzed. In case of the room temperature of $20^{\circ}C$ and the ambient temperature of $-3.2~3.8^{\circ}C$, the heating load per Ondol surface area was 115.8~167.6kJ/h ㆍ㎥ and per Ondol mom space volume was 50.2~72.7kJ/h ㆍ㎥. 6. The compressor power of heat pump fur the Ondol room heating could be determined with the heating load analyzed in this study In case of the Ondol room air temperature of 17~2$0^{\circ}C$ and the ambient temperature of -5~3.8$^{\circ}C$, the compressor power of heat pump per Ondol surface area was analyzed to be $2.3\times10^{-2}psm^2$, and per volume of Ondol room space $1.0\times10^{-2}1.4\times10^{-2}ps/m^2$ps.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2007년도 Proceedings of ISRS 2007
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• pp.149-152
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• 2007

The detection of yellow sand dust using satellite has been utilized from various bands from ultraviolet to infrared channels. Among them, Infrared channels have an advantage of detecting aerosols over high reflecting surface as well as during nighttime. Especially, brightness temperature difference between 11 and 12{\mu}m(BTD) was often used to distinguish between water cloud and yellow sand, because Ice and liquid water particles preferentially absorb longer wavelengths while aerosol particles preferentially absorb shorter wavelengths. We have found that the BTD significantly depends on surface temperature, emissivity, and zenith angle and thereby the threshold of BTD. In order to overcome these problems, we have constructed the background brightness temperature threshold of BTD and then subtracted it from BTD. Along with this, we utilized high temporal coverage of geostationary satellite, MTSAT-1R, to verify the reliability of the retrieved signal in conjunction with forecasted wind information. The statistical score test illustrated that this newly developed algorithm showed a promising result for detecting mineral dust by reducing the errors in the current BTD method.

• Journal of the korean society of oceanography
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• 제39권1호
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• pp.1-13
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• 2004

The Yellow Sea Warm Current (YSWC) and the Yellow Sea Cold Bottom Water (YSCBW) are two protruding features, which have strong influence on the community structure and distribution of zooplankton in the Yellow Sea. Both of them are seasonal phenomena. In winter, strong north wind drives southward flow at the surface along both Chinese and Korean coasts, which is compensated by a northward flow along the Yellow Sea Trough. That is the YSWC. It advects warmer and saltier water from the East China Sea into the southern Yellow Sea and changes the zooplankton community structure greatly in winter. During a cruise after onset of the winter monsoon in November 2001 in the southern Yellow Sea, 71 zooplankton species were identified, among which 39 species were tropical, accounting for 54.9 %, much more than those found in summer. Many of them were typical for Kuroshio water, e.g. Eucalanus subtenuis, Rhincalanus cornutus, Pareuchaeta russelli, Lucicutia flavicornis, and Euphausia diomedeae etc. 26 species were warm-temperate accounting for 36.6% and 6 temperate 8.5%. The distribution pattern of the warm water species clearly showed the impact of the YSWC and demonstrated that the intrusion of warmer and saltier water happened beneath the surface northwards along the Yellow Sea Trough. The YSCBW is a bottom pool of the remnant Yellow Sea Winter Water resulting from summer stratification and occupy most of the deep area of the Yellow Sea. The temperature of YSCBW temperature remains ${\leq}{\;}10^{\circ}C$ in mid-summer. It is served as an oversummering site for many temperate species, like Calanus sinicus and Euphaisia pacifica. Calanus sinicus is a dominant copepod in the Yellow Sea and East China Sea and can be found throughout the year with the year maximum in May to June. In summer it disappears in the coastal area and in the upper layer of central area due to the high temperature and shrinks its distribution into YSCBW.

• 한국항해항만학회지
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• 제29권6호
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• pp.583-588
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• 2005

하계 한국 남서연안 해역에는 저온수가 나타나고 안개가 자주 형성되는 것으로 알려져 있다. 본 연구에서는 저온수의 출현시기 및 장소와 이 해역에서 형성되는 안개에 미치는 저온수의 영향에 대해 조사${\cdot}$분석하였다. 그 결과, 저수온역은 초여름 대흑산도 부근해역에서 나타나기 시작하여, 이것은 점차 이동하여 7월 말${\~}$8월 초 진도 남서쪽 해역에 위치하고, 그 후 10월 중순경 이 해역에서 소멸된다. 그리고 이 해역에서는 주로 4${\~}$8월에 안개가 발생하는데, 특히 인근해역에 비해 해면온도가 현저하게 낮은 진도해역에서 안개 발생빈도가 높은 것으로 보아, 이 해역에 나타나는 저온수가 안개의 형성에 상당한 영향을 끼치는 것으로 사료된다.

• 설비공학논문집
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• 제29권4호
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• pp.149-158
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• 2017

In general, the air-side j and f factors of evaporators or condensers are obtained through single-design tests performed under air-dry and wet-bulb temperatures. Considering that the indoor or outdoor air temperatures vary significantly during the operation of an air conditioner, it is necessary to confirm that the experimentally-obtained j and f factors are widely applicable under variable air conditions. In this study, a series of tests were conducted on a two-row slit-finned heat exchanger to confirm the applicability. The results showed that, for the dry-surface condition, the changes of the tube-side water temperature, water-flow rate, and air temperature had virtually no effect on the air-side j and f factors. For the wet condition, however, the f factor was significantly affected by these changes; contrarily, the j factor is relatively independent regarding this change. The formulation of the possible reasoning is in consideration of the condensation behavior underneath the tube. The wet-surface j and f factors are larger than those of the dry surface, with a larger amount for the f factor.

• 한국농림기상학회지
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• 제7권1호
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• pp.35-44
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• 2005

2000년 4월부터 2003년 9월까지 광릉 산림 소유역의 플럭스 타워를 중심으로 관측된 미기후 자료(바람, 복사, 여섯 높이의 기온과 습도의 연직분포, 토양 및 나무 온도, 강수와 토양 수분)를 분석하였다. 지형의 영향으로 낮에는 상대적으로 강한 동풍이, 밤에는 약한 서풍인 산곡풍이 지배적이고 풍향의 빈도는 서풍이 두 배정도 많다. 하향 단파 복사는 여름 몬순으로 인해 5월에 가장 크고, 생육기간의 알베도는 0.12-0.16 이며 순복사는 -100～800Wm/sup-2/의 범위를 갖는다. 29m 에서 관측된 월 평균 최고 및 최저 기온(수증기압)은 각각 7-8월에 약 25℃(～25mb), 12-1월에 -6.0℃ (～3mb)이다. 기온과 수증기압의 연직분포는 식생의 계 절변화에 따라 변화한다. 월 평균 포차의 경우, 지면에서 가장 작고(< 8mb), 봄에 가장 크고 겨울에 가장 작다. 월 평균 토양 온도는 0-20℃의 범위를 보이고, 8월에 최대값이 나타난다. 월 평균 나무 온도는 -5.8～21.6℃이며, 그 변화는 월 평균 기온과 잘 일치한다. 연 강수량은 큰 경년 변동을 보이며, 7-8월의 강수량이 년 강수량의 > 60%를 차지한다. 토양수분은 관측장소에 따라 다른 연직분포를 보이며, 강수와 관련하여 물의 수평이동이 중요할 수 있음을 보인다.

• 설비공학논문집
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• 제29권6호
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• pp.316-326
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• 2017

Commercial buildings and institutions are predominantly cooled, thereby dissipating excess heat to a vertical ground heat exchanger (VGHE), than heat extracted over an annual cycle. Surface waters, such as lakes and ponds, provide a cost-effective means of reducing the VGHE length, and in balancing the thermal loads to the ground. This paper presents the measurement and analysis of the cooling performance of ground-coupled heat pump (GCHP) system, using surface water heat exchanger (SWHE) submerged in an artificial pond. In order to measure the performance of the system, we installed monitoring equipment, including sensors, for assessing the temperature and power consumption, after which the operation parameters were determined. The results from the thermal performance test for the SWHE indicate that the temperatures at the outlet of the SWHE and within the pond were affected by outdoor air temperature. In addition, the results reveal similar variation trends on temperatures; however, the peak temperatures of the SWHE were somewhat greater than those of outdoor air, due to the thermal capacity of the pond. Analyzing the cooling performance over the measurement period, the average coefficient of performance (COP) of heat pump was found to be 5.71, while that for the entire system was 2.99.

• 설비공학논문집
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• 제12권4호
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• pp.381-387
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• 2000

An experimental study on the stratified fluids was carried out to investigate the flow characteristics, heat transfer through the interface of fluids, and the applications of thermal behaviors in the square cavity. The same volume of water and silicon oil was filled in it. The experiments were performed with the variations of initial temperatures and cooling surface temperatures. And the effect of vertical or horizontal cooling surface positions in the square cavity was investigated. When the cooling surface temperatures were $-4^{\circ}C$ , the supercooling phenomena were observed for both cases of cooling surface positions in the full region regardless of the initial temperature of fluid. In the square cavity with horizontal cooling surfaces, the lower the initial temperatures were, the longer the supercooling durations were, and with vertical cooling surface the lower the initial temperatures were, the shorter the supercooling durations were.

• Journal of Mechanical Science and Technology
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• 제16권5호
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• pp.696-702
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• 2002

In the present paper, the effects of inlet pressure on the heat and mass transfer rates of an air cooler are numerically predicted by a local analysis method. The pressures of the moist air vary from 2 to 4 bars. The psychrometric properties such as dew point temperature, relative humidity and humidity ratio are employed to treat the condensing water vapor in the moist air when the surface temperatures are dropped below the dew point. The effects of the inlet pressures on the heat transfer rate, the dew point temperature, the rate of condensed water, the outlet temperature of air and cooling water are calculated. The condensation process of water vapor is discussed in detail. The results of present calculations are compared with the test data and shows good agreements.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2004년도 학술대회지
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• pp.143-148
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• 2004

In order to see physical characteristics of water masses and tidal currents in Gamak Bay, some field surveys have been conducted using ADCP, Aanderaa current meter and CTD from May 17 to June 3, 2004. The northwest of the bay appeared to have a high temperature and a high salinity so that it coincided with the previous results. The distribution of temperature and salinity seemed to reflect the characteristics of water masses. At the south mouth of the bay, a northwestward-southeastward flow was dominant at the surface layer while a northeastward-southwestward flow was dominant at the bottom layer.