• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.304-308
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• 2008

The optimal design of two stage evaporation & absorption system which is related to the large temperature difference system was investigated numerically in the absorption refrigeration system. The concentrations at inlet & oulet of absorber are 62.9% and 56.9%, but in two stage absorption system the values are 62.2% and 56.2%. Therefore strong solution & weak solution became diluted than the standard value. The amount of weak solution circulation can be reduced in absorption refrigeration system, and the sensible heat load is more reduced to enhance the COP of system. As UAR is increased, COP becomes larger, and this means the role of top section is more important than bottom section in two stage evaporation & absorption system. But the increase of COP becomes slower at 0.7 of UAR ratio. The performance of Type2 is higher than Type1 in COP with the flow direction of cooling waters. This phenomena is due to the active absorption of vapor -absorption & lower temp. cooling water is more effective. The pressure at bottom section becomes higher & that at top section becomes lower and therefore the circulation rate can be diminished more.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 동계학술발표대회 논문집
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• pp.203-211
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• 2008

The optimal design of two stage evaporation & absorption system which is related to the large temperature difference system was investigated numerically in the absorption refrigeration system. The concentrations at inlet & oulet of absorber are 62.9% and 56.9%, but in two stage absorption system the values are 62.2% and 56.2%. Therefore strong solution & weak solution became diluted than the standard value. The amount of weak solution circulation can be reduced in absorption refrigeration system, and the sensible heat load is more reduced to enhance the COP of system. As UAR is increased, COP becomes larger, and this means the role of top section is more important than bottom section in two stage evaporation & absorption system. But the increase of COP becomes slower at 0.7 of UAR ratio. The performance of Type2 is higher than Type1 in COP with the flow direction of cooling waters. This phenomena is due to the active absorption of vapor -absorption & lower temp. cooling water is more effective. The pressure at bottom section becomes higher & that at top section becomes lower and therefore the circulation rate can be diminished more.

• Journal of Advanced Marine Engineering and Technology
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• 제40권4호
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• pp.282-287
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• 2016

최근 조선사들은 선박이 운항되는 연안 환경의 개선과 보호를 위하여 $CO_2$를 절감할 수 있는 친환경 선박과 함께 선박 운항 중 소비하는 에너지의 절감을 위한 고효율화 선박 개발의 노력도 활발하게 수행하고 있다. 본 연구에서는 전기로 구동되는 선박의 증기압축식 냉동기 대신에 선박 엔진 자켓수의 폐열을 이용하여 냉방을 할 수 있는 흡수식 냉동기의 적용 가능성과 냉각시스템에 냉매를 적용하는 시스템의 성능을 분석하였다. 연구결과, 해수와 열교환하여 액화될 수 있는 냉매들 중 R236fa가 가장 적합한 냉매로 분석되었으며, 이를 적용한 흡수식 냉동기의 COP는 0.798로 육상의 냉각탑을 이용한 수랭식보다 15% 그리고 해수 열교환기식 수랭식보다 5% 향상되었다. 냉동능력 1RT를 얻기 위한 LiBr 흡수용액 순환량은 0.013 kg/s로 수랭식 보다 25% 이상 감소하며, 냉각 매체 순환량도 수랭식의 15.7%에 불과한 매우 효과적인 냉동기가 되었다. 해수온도가 $18^{\circ}C$ 이하로 낮으면 발생하게 되는 LiBr의 결정화는 재생기에서 배출되는 엔진 자켓수의 온도를 이용하여 해수 온도를 상승시킴으로써 방지할 수 있다.

• 한국수소및신에너지학회논문집
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• 제15권2호
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• pp.144-151
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• 2004

The effect of the cobalt content on the thermodynamic and, heat and mass transfer properties of the $MmNi_{5-y}B_{y-z}C_z(y=0.5{\sim}1.5,\;z=0.5)$hydrogen storage alloys has been studied systematically. The P-C isotherms curves show that with increasing cobalt content in the alloys, the plateau pressure of the hydrogen absorption and desorption and enthalpy(${\Delta}H$) increases steeply and the plateau region becomes flat, while entropy(${\Delta}S$) decreases. Also at the constant cobalt content the hydrogen transfer rate decreases with the reaction temperature, while the initial reaction kinetics increases. But the initial reaction with hydrogen completes within 1min, although the reaction proceeds about 30minutes thereafter.

• 한국기계가공학회지
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• 제18권10호
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• pp.20-26
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• 2019

This study was conducted on cooling systems in which, for the first time at home and abroad, cold water panels are embedded in the walls of small buildings for radiant cooling by heat absorption with cold water. In summer, cold water is circulated through cold water (chiller) circulation tubes embedded in three walls (two side walls and one rear wall) of a building to implement radiant cooling by the coldness of the water. From the results of this study, the experimental and theoretical natural convection heat transfer coefficients were relatively well-matched over the entire experimental range, thereby verifying the reliability of the experimental results. The surface temperature reduction rate of the walls in which cold water panels are embedded was large whereas that of the walls where no cold water panels are embedded was very small.

• Journal of the Korean Physical Society
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• 제73권10호
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• pp.1584-1588
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• 2018

During hyperthermia therapy, cancer cells are heated to a temperature in the range of $40{\sim}45^{\circ}C$ for a defined time period to damage these cells while keeping healthy tissues at safe temperatures. Prior to hyperthermia therapy, the amount of heat energy transferred to the cancer cells must be predicted. Among various non-invasive methods, the thermal prediction method using the specific absorption rate (SAR) is the most widely used method. The existing methods predict the thermal distribution by using a single constant for the mass density in one organ through assignment. However, because the SAR and the bio heat equation (BHE) vary with the mass density, the mass density of each organ must be accurately considered. In this study, the mass density distribution was calculated using the relationship between the Hounsfield unit and the mass density of tissues in preceding research. The SAR distribution was found using a quasi-static approximation to Maxwell's equation and was used to calculate the potential distribution and the energy distributions for capacitive RF heating. The thermal distribution during exposure to RF waves was determined by solving the BHE with consideration given to the considering contributions of heat conduction and external heating. Compared with reference data for the mass density, our results was within 1%. When the reconstructed temperature distribution was compared to the measured temperature distribution, the difference was within 3%. In this study, the density distribution and the thermal distribution were reconstructed for the agar phantom. Based on these data, we developed an algorithm that could be applied to patients.

• 한국주조공학회지
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• 제2권1호
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• pp.2-11
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• 1982

In order to investigate the relationship between the thermal characteristics of the various molds as green sand mold, dry sand mold, $CO_2$ mold and shell mold, and the solidification characteristics of molten metal, the thermal analysis of rarious molds and melt were performed. The structure of Al-Castings was a/so observed. Results obtained in this experiment were as follows : 1) The heating rate of the molds was increased in the order of green sand mold, $CO_2$ mold, dry sand mold and shell mold, On the other hand the solidification time of the melts was shortened in the order of dry sand mold castings, $CO_2$ mold castings, green sand mold castings and shell mold castings. 2) The arrest temperature period in the heating curve of the green sand mold was resulted from the eraporation of moisture contained in mold, which was transfered to the outer side of the mold. 3) The temperature fluctuation of the melt in the shell mold was considered to be resulted from the combution heat of resin contained in the mold. 4) The amounts of heat absorption of the molds were increased in the order of dry sand mold, $CO_2$ mold, green sand mold and shell mold. 5) The higher the solidification rate was, the longer was its shrinkage pipe and the finer its grain size.

• 대한치과기공학회지
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• 제20권1호
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• pp.21-25
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• 1998

A detailed description of the Laboratory Processing procedures for Soft Base Denture that varies from those offered by the manufacturer has provid to be effective. As follows ; 1. Pomotion of patient's comfortability 2. increase in denture retention 3. because of the same heat-curing denture materials used improves bonding & endurance 4. often used denture refitting 5. reducing the rate of alveolar absorption The processing for soft base denture is very sensitive, consequntly.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 동계학술발표대회 논문집
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• pp.324-329
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• 2008

The liquid cooling effect of a natural convection type radiator by using the PCM has been investigated experimentally. The radiator size is $423{\times}295{\times}83$ mm and PCM container size is $398{\times}270{\times}26$ mm. The objective is elapsed time higher than maximum time to reach for maximum operating temperature of a general liquid cooling radiator. This study, in order to study on the effects of the phase-change phenomenon, carried out the various mass flow rate, input electric power, ambient and melting point of three type PCM. For the above experimental parameter, the melting time was performed about 180/250/560 min at input power 150 W and ambient $30^{\circ}C$ from using the three type PCM(PCM_S1/S2/S3) respectively. Furthermore, the effects of the thermal dissipation was decreased higher input power than lower input power at heating block and melting time of PCM. However, the effects of mass flow rate did not nearly affect of the thermal performance especially.

• 생명과학회지
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• 제32권3호
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• pp.232-240
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• 2022

리포좀을 제조하는 방법으로 여러가지 알려져 있다. 그 중 Bangham법이 가장 간단하며 일반적으로 많이 이용되어 왔다. 소규모 실험 수준에서는 효과적으로 리포좀을 제조할 수 있지만 유기용매 제거의 어려움과 지질막 형성에 반응기 크기 등의 문제로 대규모 생산을 할 수 없다는 문제점이 있다. 반면 톤(t) 단위로 대량생산이 가능한 Emulsion Method는 균일한 입자를 가진 리포좀으로 제조가 가능하나 포집률이 현저히 낮은 단점이 있다. 그래서 본 연구에서 높은 포집율과 안정성을 향상시킨 Heating Method으로 리포좀 최적의 공정방법을 개발하여 포집률, 입자크기, 제타전위 및 SD rat에 경구 투여하여 흡수율 실험을 수행하였다. 약 214 nm의 작고 균일한 리포좀을 형성하였고, 포집률은 Emulsion Method는 26.46%, Heating Method는 38.67%으로 Heating Method법을 제조된 리포좀이 높은 포집률을 보여주는 것을 확인할 수 있었다. 혈중 농도 대비 모든 군에서 1.5-2배 정도 증가한 경향을 보여주었고, 4-12 hr까지 점차 낮아지는 양상을 나타냈다. Ascorbic acid powder의 혈중 최고 농도는 약 12.017 ㎍/ml, Emulsion Method 리포좀 13.871 ㎍/ml, Heating Method 리포좀은 16.322 ㎍/ml 순으로 ascorbic acid powder보다 향상된 흡수율 결과를 보여주었다.