• 한국지구과학회지
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• 제28권5호
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• pp.598-602
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• 2007

A long-term in situ observation was carried out in the Ice-valley at Milyang in order to explain the factors and processes associated with the summertime ice formation. The variation of temperature inside Ice-valley in relation with ice formation in summer time was found to depend on precipitation rate in spring and cold air sinking in autumn and winter. The rate of temperature rising tends to correspond to sensible heat release depending on the precipitation amount at the freezing location. The reason of the cold air accumulation in a talus in the Ice-valley is the cold air sinking over the surface of talus due to the occurrence of outside clod air mass and the accumulated cold air from autumn to spring flow outside at the bottom of talus. The out-flowing cold air can result in the ice formation in the hot summer.

• 설비공학논문집
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• 제14권12호
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• pp.1071-1077
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• 2002

Ice adhesion on cooling wall is very important in continuous ice formation. The purpose of the present study is to investigate the possibilities of a three-component aqueous solution as a thermal storage material for the continuous ice formation. By freezing under stirring the solution of 300 mL in a stainless steel vessel which was immersed and cooled in a temperature controlled bath, an ice slurry was formed experimentally with measuring the temperature and stirring load variation. From the experiment, the ice adhesion was suppressed when the supercooling degree decreased and the concentration of aqueous solution increased.

• 설비공학논문집
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• 제14권12호
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• pp.1063-1070
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• 2002

To resist ice adhesion on cooling wall is concerned to continuous ice formation in thermal storage system. In this study, ice slurries were formed with two ecological aqueous solution, one is ethanol+silanol and the other is propylene glycol+silanol. By freezing under stirring the solution of $300m\ell$ in a stainless steel vessel which was immersed and cooled in a temperature controlled bath, the shape of ice slurry and the strength of ice adhesion on wall was observed with measuring the temperature and stirring load variation. As the concentration is smaller and the supercooling degree is larger, the ice adhesion is easy to occur. When the stirring load is larger than$ 2.1\times10^{-5}W$, the ice adhesion occurred.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.223-228
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• 2001

The thermoacoustic refrigerator has not only considerable possibility but also commercial usability, because it has high reliability, lower vibration, no moving part, and can easily be constructed. In this study, The thermoacoustic refrigerator were constructed. The apparatus is capable of driving closed systems containing He or air at mean pressures ranging from 1-9.3 bar, at frequencies ranging from 100-1000Hz. The resonance characteristics of the thermoacoustic refrigerator were investigated for better performance, The resonance tube is 340.5mm in length. In case of using air as a coolant. Freezing frequency is 174Hz, In case of using He as a coolant Freezing frequency is 625Hz. Using He, The cold-part temperature of the heat exchanger fell to $-23.7^{\circ}C$ after 120 minutes in 70W.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.240-245
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• 2000

In this study, thickness, density and effective thermal conductivity of frost forming on the horizontal cylinder were measured with various air temperature and humidity. Reynolds number and temperature of cooling surface are controlled 17300 and $-l5^{\circ}C$ respectively. In each case of air temperature $5^{\circ}C,\;10^{\circ}C,\;15^{\circ}C,$ varying absolute humidity, experiments were executed. In measuring frost surface temperature and thickness of frost layer, infrared thermocouples and CCD camera were used. Frost was gathered from cylinder to measure mass of frost layer. Experimental data showed that the thickness and effective thermal conductivity of the frost layer increase with respect to time. Thickness of frost layer increase with humidity increasing, and density of frost layer increase with air temperature rising. Frost growth with air temperature and density of frost layer with humidity are affected by whether dew point is below or above freezing point.

• 한국태양에너지학회 논문집
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• 제25권4호
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• pp.37-44
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• 2005

An experimental study was conducted to analyze performance of a heating system with variation of control logic of the system. The system uses a solar as heat source and composed with heat pump that uses R-22 as working fluid. The difference between the developed system and the commercially available heating system is working fluid. The solar assisted heating system which was widely distributed in the market uses water as a working fluid. It could be freezing in case of the temperature drops down under freezing point. The anti-freezing fluids such as methyl-alcohol or ethylene-glycol are mixed with the water to protect the freezing phenomena. However, the system developed in this study uses a refrigerant as a working fluid. It makes the system to run under zero degree temperature conditions. Another difference of the developed system compare with commercial available one is auxiliary heating method. The developed system has removed an auxiliary electric heater that has been used in conventional solar assisted heating system. Instead of the auxiliary electric heater, an air source heat exchanger which generally used as an evaporator of a heat pump was adapted as a backup heating device of the developed system. As results, an efficiency of the developed system is higher than a solar assisted heat pump with auxiliary electric heater. The merit of the developed system is on the performance increment when the system operates at a lower solar energy climate conditions. In case of the developed system operates at a normal condition, COP of the solar collector driven heat pump is higher than the air source heat exchanger driven heat pump's.

• 설비공학논문집
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• 제29권6호
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• pp.289-296
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• 2017

This study aimed to analyze the deck floor heating system of an outdoor swimming pool in terms of the thermal capacity/output and the surface temperature distribution based on the outdoor temperature, to design for anti-freezing during winter. Through the transient heat transfer simulation with PHYSIBEL and theoretical equations, the surface temperature distribution of the floor heating system at two outdoor conditions in Jeju, were calculated and evaluated. The results indicate that the specific thermal output required for maintaining $4^{\circ}C$ surface temperature at the design outdoor temperature of $0.1^{\circ}C$, was about $90W/m^2$. This performance analysis can be applied for future design criteria, including optimizations of system capacity and size.

• 한국식품위생안전성학회지
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• 제10권2호
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• pp.97-102
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• 1995

For improved preservation of boiled-dried anchovies, the current preservation method of corrugated-cardboard box packaging and freezing below -18$^{\circ}C$ was compared to the nylon/polyethylene(NY/PE) packaging along with cooling temperature ranging from 5$^{\circ}C$ to 1$0^{\circ}C$ as well as ambient condition for eight months by determining physicochemical quality of stored samples. Lipid oxidation of stored anchovies and their browning increased with storage time. The phenomenon was delayed under the conditions of lower temperature and air-tight packaging. As quality-indicative criteria of stored anchovies, carbonyl value(r=-0.989), browning (r=-0.949) and color a value(r=-0.989), browning(r=-0.965), Hunter's color b value(r=-0.949) and color a value(r=-0.940) showed a highly-negative correlations with organoleptic qualities of the samples. Based on the above results, air-tight packaging in a laminated film and subsequent storage at cooling temperature was found to be a possible alternative to the current freezing-storage of boiled-dried anchovies from the physicochemical point of view.

• 한국수산과학회지
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• 제15권2호
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• pp.111-116
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• 1982

말쥐치를 보다 효과적으로 이용하기 위한 하나의 방법으로서 말쥐치 동건품의 가공사건 및 저장중의품질변화를 실험하였다. 동결온도 $-10^{\circ}C$이고 송풍해동조건이 온도 $56\pm2^{\circ}C$, 풍속 1 m/sec 일 때 동결시간 10시간, 해동시간2시각, 동결 및 해동포수는 5소파 가장 적합하였다. 이 때 제품의 수분사양은 $23.6\%$, 수율은 $10.2\%$였다. 상온에서 함기포장하여 저장한 결과 90일까지는 품질에 큰 변화 없이 저장 가능했다. Omission test결과 제품의 맛에는 유리아미노산과 5'-mononucleotide가 주된 구실을 한다는 것을 알 수 있었다. 또한 말쥐치 동건품과 시판 동건명태는 관능 검사결과 맛, 냄새, 텍스튜어 등이 거의 비슷하였다.

• 한국축산식품학회지
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• 제33권6호
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• pp.763-771
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• 2013

본 연구에서는 전기자장 및 송풍식 냉동 방법이 냉동 중육의 온도 변화 및 해동 후의 이화학적 품질에 미치는 영향을 살펴보았다. 우육(등심 및 우둔), 돈육(삼겹 및 뒷다리) 및 계육(가슴 및 다리)을 구매하여 공시 재료로 사용하였으며 냉동은 전기자장 냉동법 및 송풍식 냉동법($-20^{\circ}C$, $-45^{\circ}C$)의 세가지 방법을 사용하였다. 육의 이화학적 특성변화를 분석하기 위하여 해동감량, 가열감량, 보수력 및 일반성분 분석을 실시하였다. 냉동 중 육의 온도 변화 비교에서는 축종 및 부위에 관계없이 전기자장 냉동법(2 h)의 냉동 완료 시간이 $-20^{\circ}C$ 및 $-45^{\circ}C$ 송풍식 냉동법(24 h 및 8 h)보다 짧은 결과가 나타났다. 해동 후 품질 평가 결과에서 해동감량은 전기자장 냉동법을 이용한 우육 등심이 4.80%로 가장 낮았지만, 가열감량과 보수력에서는 43.7% 및 60.7%로 가장 높았다(p<0.05). 부위 및 냉동 방법에 따른 회분 함량에는 차이가 없었지만, 조단백, 조지방 및 수분함량은 유의적인 차이를 나타내었다(p<0.05). 지방함량은 전기자장 냉동법 우육의 등심과 우둔이 각각 10.4% 및 4.7%로 낮았지만, 수분함량은 67.1% 및 71.9%로 가장 높았다(p<0.05). 단백질 함량은 계육 가슴(23.4%, 24.1% 및 23.1%)에서 가장 높았으며, 보수력에 영향을 미쳤을 것으로 판단되었다. 본 실험 결과 전기자장 방법이 송풍식 방법보다 냉동 시간이 짧고 해동감량, 가열감량 및 보수력 실험에서 유의적으로 좋은 결과를 나타내어 식육의 품질을 떨어뜨리지 않을 것으로 기대할 수 있었으며, 축종 및 부위별 비교 결과 수분과 단백질 함량이 낮고 지방함량이 높은 부위일수록 드립이 적은 것으로 판단되었다.