• International Journal of Air-Conditioning and Refrigeration
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• v.7
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• pp.101-111
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• 1999

The effect of various conditions of frosting and defrosting on the defrosting behavior of a fin-tube heat exchanger has been examined experimentally. An electric heater is used for defrosting in a fin-tube heat exchanger. There are several local maxima in the water draining rate. The amount of residual water on the heat exchanger after completion of defrosting is kept constant due to surface tension on the heat exchanger. Without considering degradation of the thermal performance due to the frosting, the defrosting efficiency is improved with increasing amount of frost irrespective of the frosting condition. The defrosting behavior is affected by frosting density as well as frost accumulation, both of which vary with the experimental operating conditions. The heat loss to the surrounding air decreases, and melting and defrosting efficiencies show high values with decreasing heat input.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.10
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• pp.781-785
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• 2002

The effects of different surfaces on dry and wet frosting test were experimentally investigated. The results of experiment were compared by the performance evaluation coefficient (PEC). Results showed that the air-side pressure drop of lacquer coated evaporator increased by 5% as compared to the plasma treated one. It was also found that the Plasma coated evaporator is lower than lacquer coated one in the PEC ratio.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.8
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• pp.671-675
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• 2002

The gas adsorption efficiency for various surfaces with three different characteristics has been reviewed. The dimethyl disulfide gas has been used to investigate characteristics of gas adsorption for different surface characteristics such as plasma treated, lacquer coated and untreated. Three different surfaces were evaluated in dry conditions initially and tested at wet surface conditions with spraying water to evaluate the gas adsorption efficiency which usually occurred at defrost cycles. The results show that the gas adsorption of the plasma treated sample has better performance than others. The lacquer coated and untreated samples showed the similar result, but the lacquer coated sample showed a slightly better performance.

• Journal of Institute of Convergence Technology
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• v.1 no.1
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• pp.1-4
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• 2011

The object of this experimental study is to investigate the effect on frost prevention and delay by the method of alternating the function of outdoor coil rows under the frost conditions ($2^{\circ}C/1^{\circ}C$). The heat pump system with the new method can make frost delay time longer and eliminate frost effectively. It is withstand over 280 minutes without a conventional defrosting method. Maximum COP in case of adopting new method is 13% higher than that in case of reverse cycle defrosting method. Also in case of moving air injection duct faster, the frost delay time is lengthened and its COP is enhanced more.

• Korean journal of food and cookery science
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• v.28 no.5
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• pp.623-628
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• 2012

The study was about to produce red ginsengs easily, using a household microwave oven to promote the consumption of fresh ginsengs in the home. Producing red ginsengs with a household microwave oven 'defrost function' takes 13 minutes (A), 'cook function' 6 minutes (B), and finally, 'defrost function' 44 minutes (C). For characteristics of microwave-produced red ginsengs, total saponin loss, color of powder, polyphenol content and saponin composition were compared with common red ginsengs. The color test for red ginseng powder showed that the color of household microwave-produced 6-minute cooked red ginseng (B) or 44-minute defrosted red ginseng (C) was closer to that of the common red ginsengs (E). The total saponin content in water eluted during red ginseng production showed that the saponin loss in microwave red ginseng was negligible compared to the common red ginsengs. Microwave red ginsengs showed no difference in phenol content that of the and higher total ginsenoside content than common red ginsengs. The ginsenoside $Rg_1$, Re, Rf, $Rg_2+Rh_1$, $Rb_1$, Rc, $Rb_2$, $Rb_3$, Rd and $Rg_3$ contents of microwave red ginsengs (A, B) were higher compared to that of the common red ginsengs; the ginsenoside Re, Rc, $Rb_2$, $Rb_3$, Rd and $Rg_3$ contents of 44-minute defrosted red ginseng (C) were higher compared to the common red ginsengs. It is considered that red ginseng production, using microwave oven at home, can be a fast and convenient way to produce highly functional red ginsengs with high ginsenoside content.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.2
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• pp.121-129
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• 2016

The noise pattern of a household refrigerator is dependent on the characteristics of its operating cycle which is repeated with a specific pattern depending on various parameters, such as room temperature and performance of its mechanical parts. Analysis of noise pattern is essential prior to evaluation of sound quality of a refrigerator. In this study, 14 units of refrigerator were classified into 4 types according to noise pattern and sort of mechanical part, which helps to analyze characteristics of refrigerator noise. Sound quality metrics(loudness, sharpness, roughness, and fluctuation strength) were calculated to compare noise pattern of the 4 types of refrigerator. The results of this study can be useful to decide noise performance of refrigerator.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.10 no.6
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• pp.649-657
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• 1998

In this study, the effects of the various conditions of frosting and defrosting on the behavior of defrosting in a fin-tube heat exchanger have been examined experimentally. The electric heater is used for defrosting in a fin-tube heat exchanger It is shown that there are several local maxima in the water draining rate. The amount of residual water on the heat exchanger after the completion of defrosting is kept constant due to surface tension on the heat exchanger. Without considering the degradation of the thermal performance due to the frosting, the defrosting efficiency is improved with increasing amount of the frost irrespective of the frosting condition. The defrosting behavior is affected by the frosting density as well as the frost accumulation, which vary with the experimental operating conditions during the frosting period. The heat loss to the surrounding air decreases, and the melting and defrosting efficiencies show high values with decreasing heat input.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.5
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• pp.436-443
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• 2005

Experimental study was performed to understand the operation of an on-site showcase working in a super discount store. Inlet and outlet temperatures of evaporator, condenser, expansion valve and compressor were measured for both air and refrigerant sides. Electric power consumption of compressors, defrosting heaters, cooling water pumps and etc. were measured. The operating characteristics of the showcase system under various working conditions were analyzed and discussed. During the defrosting process, the air temperature inside the showcase increased to $15^{\circ}C$, which gave harmful effect to the frozen food. The collected data will serve as valuable information for diagnosing and improving the performance of showcases.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.11
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• pp.1084-1091
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• 2004

In automotive air handling system, mixing of air streams by the cooler and the heater affects the comfort of cabin room. In the present study, computer-aided analysis is done to improve the thermal comfort and for the optimal design of automotive HVAC system. The simulation software used was FLUENT, and complicate geometries were created by three dimensional CAD. Air flow volume, fir distribution rate and temperature controllability and temperature differences between upper and lower discharge air are analyzed through numerical simulation at vent, floor and defrost mode. Also, velocity vector of sirocco fan is investigated through the scroll housing. The velocity vector magnitude is larger at lower region of fan than that at any other regions. Recirculation and disturbance of air is relatively high near the cut-off edge in the scroll housing. By using the results of this study, the time for prototype production can be reduced and timely decisions can be made to determine initial design directions.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 1997.11a
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• pp.289-296
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• 1997

This paper discribes an experimental explosion risk assessment study on refrigerators containing flammable hydrocarbon refrigerant. A refrigerator used in this study is a larder fridge type, 215 liter in volume. The hydrocarbon refrigerant used in the refrigerator is iso-butane(C$_4$H$_{10}$). For the explosion safety assessment of the refrigerator, temperature of compressor, cooling air circulation fan motor, defrost heater and inner lamp were measured during the operation. And to confirm the ignitablity of flammable gas by the electric spark of the switches of the refrigerator, ON-OFF test of all switches were conducted with compulsorily near the stoichiometric concentration atmosphere of iso-butane-air mixture. As the result of experiment above mentioned and another experiment for the explosion safety assessment, we can conclude that explosion hazard in connection with the use of hydrocarbon refrigerant was few.w.