• Journal of the Korean Solar Energy Society
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• v.35 no.6
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• pp.25-33
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• 2015

In this study, heating performance of the air-cooled heat pump with vapor-injection (VI) cycles, re-heater and solar heat storage tank was investigated experimentally. Devices used in the experiment were comprised of a VI compressor, re-heater, economizer, variable evaporator, flat-plate solar collector for hot water, thermal storage tank, etc. As working fluid, refrigerant R410A for heat pump and propylene glycol (PG) for solar collector were used. In this experiment, heating performance was compared by three cycles, A, B and C. In case of Cycle B, heat exchange was conducted between VI suction refrigerant and inlet refrigerant of condenser by re-heater (Re-heater in Fig. 3, No. 3) (Cycle B), and Cycle A was not use re-heater on the same operating conditions. In case of Cycle C, outlet refrigerant from evaporator go to thermal storage tank for getting a thermal energy from solar thermal storage tank while re-heater also used. As a result, Cycle C reached the target temperature of water in a shorter time than Cycle B and Cycle A. In addition, it was founded that, as for the coefficient of heating performance($COP_h$), the performance in Cycle C was improved by 13.6% higher than the performance of Cycle B shown the average $COP_h$ of 3.0 and by 18.9% higher than the performance of Cycle A shown the average $COP_h$ of 2.86. From this results, It was confirmed that the performance of heat pump system with refrigerant re-heater and VI cycle can be improved by applying solar thermal energy as an auxiliary heat source.

• Journal of The Association for Neo Medicine
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• v.1 no.1
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• pp.103-113
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• 1996

It is thought that the quantity and quality of the heat stimulation and the mechanism of heating process are important to understand the moxa-combustion. In order to get the basic data on the effective moxa-combustion method, combustion temperature changes (average temperature, peak temperature, average gradient temperature and maximum gradient temperature) of the heating period were measured respectively by the density of moxa material. For the experiment, samples of $300mg/0.26cm^3$ , $400mg/0.26cm^3$ and $500mg/0.26cm^3$ of moxa material were molded in a conical mold with each 10mm in diameter and height. 1. The average temperature and peak temperature of heating period on the moxa-combustion showed higher in the $400mg/0.26cm^3$ and $300mg/0.26cm^3$ than in the $500mg/0.26cm^3$ sample respectively. 2. The average gradient temperature of heating period on the moxa-combustion rose quickly in the $300mg/0.26cm^3$, $400mg/0.26cm^3$ and $500mg/0.26cm^3$ in that order and the maximum gradient temperature rose more quickly in the $300mg/0.26cm^3$ and $400mg/0.26cm^3$ than in the $500mg/0.26cm^3$ sample respectively. According to the above results, it is concluded that the density of moxa material is (the) more important (factor) than the weight or volume of moxa material on the combustion temperature changes of the heating period for the evaluation of the quality and quantity of moxa-combustion.

• Journal of Biosystems Engineering
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• v.16 no.1
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• pp.83-89
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• 1991

One of the most serious problems in Korean sericulture farms is to improve the adiabatic conditions for the simple silkworm rearing houses which has been widely adapted since early 1980'. Thus, this study is aimed to solve the problems by selecting the thermal screen material and by finding the method of its instalation. For the study, 4 kinds of materials which are (1) TE005,(2) NW60, (3) NW300 and (4) AL110 are selected and 4 different types of methods which are surrounding boundary of rearing bed(type A), surrounding inside of wall and ceiling (type B), installing on inside of wal ony (type C) and installing on ceiling Inly (type D) are installed. Decision criteria of the best combination of screen material and installation methods is made by calculating the heating load coefficients and by testing the application at the simple silkworm rearing houses. The obtained results are summarized as follows ; 1. The effect of thermal screen on reducing the thermal energy is remarkable. It saves energy more 50% than unscreened simple silkworm rearing houses. 2. From a stand point of a good screed material on thermal energy reduction, the NW300, AL110 and PE005 are recommanded materials. However, NW60 and PE005 are regarded as desirable materials from the practical point view. 3. Also, the effect on thermal energy reduction is largely affected by the method of thermal screen installation. The surrounding boundary of the silkworm rearing bed(type A) is the most desirable method to reduce the energy, which saves 56.6% of it. 4. In the practical application, NW60 and type A is considered to be the best combination of material and installation method. By this combination, the level of maximum heating load can be reduced at the rate of 43% for spring season and 40% for autumn season. 5. Another heating method, comparted heating, can be recommended to save the energy.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.24 no.5
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• pp.340-344
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• 1991

On heating and fleering food-stuffs, it is very important to obtain informations about thermophysical properties of fishes for designing of freezing and heating equipment and analyzing of physico-chemical reaction during storage. It is particularly necessary to measure denaturation enthalpy, temperature, latent heat of freezing, activation energy, enthalpy, entropy and free energy on freezing and heating rate. In this study, DSC was used to study effects of freezing and heating rate on thermophysical properties and denaturation temperature on scanning rate $2.5-10.0^{\circ}C/min$. On increasing scanning rate, denaturation temperature of protein and lipid incresed and freezing point, activation energy, enthalpy, entropy were decreased. In freezing process free energy of fishes were found to be $14.2-18.9 kcal/mol$.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.4
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• pp.370-376
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• 2005

For the purpose of investigating the effective removal of heating/cooling load from light-weighted building envelope, two air-conditioning systems, conventional parameter air-conditioning system and air-barrier system, are evaluated and compared by both experiment and simulation with six different cases during heating and cooling season. In addition, the characteristics of window-side building thermal load are assessed by varying supply air velocity in order to seek the optimal system operation condition. The results are as follows. 1) Air-barrier system is more effective to remove heating/cooling load at perimeter zone than conventional parameter air-conditioning system. Moreover, the better effectiveness appears during cooling season than during heating season. 2) The experiment during cooling season provides that indoor temperature of air-barrier system shows $1^{\circ}C$ less than that of the conventional system with similar outdoor air temperature profile, and indoor temperature distribution is more uniform throughout the experimented model space. It concludes that air-barrier system can achieve energy saving comparing to the conventional system. 3) The capturing efficiency of air-barrier system is 0.47 on heating season and 0.2 on cooling season with the same supply air volume. It results that the system performs effectively to remove building thermal load, moreover demonstrates high efficiency during cooling season. 4) The simulation results provide that capturing efficiency to evaluate the effective removal of building load from perimeter zone shows high value when supply air velocity is 1 m/s.

• Korean Journal of Food Science and Technology
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• v.44 no.1
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• pp.28-33
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• 2012

The effect of puffing conditions on the physical properties and sensory evaluations of a puffed snack (ppeongtuigi) made of purple sweet potato flour was investigated. The snacks consisted of coated artificial rice with purple sweet potato flour with water, tempered to 7%, 9% and 11% moisture. The coated material was puffed at 236, 241, or $246^{\circ}C$ for 4, 5, or 6 s. The $L^*$ value decreased as the heating time increased. The $a^*$ and $b^*$ values, specific volume, and hardness increased with increasing heating temperature and heating time. Puffed snacks produced under conditions of higher moisture (7%), higher heating temperature ($246^{\circ}C$), or longer heating time (5 s) showed high scores for appearance, color, taste, and overall acceptability in sensory evaluations.

• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.3
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• pp.113-124
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• 2012

Reliable estimation of energy load inside the greenhouse and the selection of cooling and heating facilities are very important preceding factors to save energy as well as initial and maintenance costs of operating a greenhouse. Recently, building energy simulation (BES) technique to simulate a model similar to the actual conditions through a variety of dynamic simulation methods, and predict and analyze the flow of energy is being actively introduced and developed. As a fundamental research to apply the BES technique which is mainly used for analysis of general buildings, to greenhouse, this research designed four types of naturally-ventilated greenhouses using one of commercial programs, TRNSYS, and then compared and analyzed their energy load properties, by applying meteorological data collected from six regions in Korea. When comparing the greenhouse load of each region depending on latitude and topographical characteristics through simulation, Chuncheon had nearly 9~49 % higher heating load per year than other regions, but its annual cooling load was the reverse to it. Except for Jeju, 1-2W type greenhouses in five regions showed about 17 % higher heating load than a widespan type greenhouse, and 1-2W type greenhouses in Chuncheon, Suwon, Cheongju, Daegu, Cheonju and Jeju had 23 %, 20 %, 17 %, 16 %, 18 % and 20 % higher cooling load respectively than a wide span-type one. Glasshouse and vinyl greenhouse showed 8~11 % and 10~12 % differences respectively in heating load, while 2~10 % and 7~10 % differences in cooling load respectively.

• Resources Recycling
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• v.9 no.3
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• pp.13-21
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• 2000

This study describes to analyze the heat transfer characteristics of waste solvent recovery system using a double pipe heat exchanger heating solvent by the hot oil. The solvent recovery system consists of the feeding pump, the double pipe heat exchanger, the vacuum spray chamber, and the condenser. A double pipe heat exchanger consists of the first section to conduct the heating of solvent to the thermal saturated point and the second section to evaporate the saturated solvent. The heat transfer area for vaporization of water, benzene and alkylbenzene was predicted by the heat balance modelling and experimentally measured from the temperature distribution as a function of solvent flow rate and heating temperature. The required heat transfer area for vaporization was increased with increasing solvent flow rates and with decreasing heating temperatures due to decreased quantity of transferred heat per the unit area. Theoretical modelling of the heat transfer area for solvents vaporization in the pipe showed good agreement with experimental results. Results showed to be suitable for the waste solvent recovery using a double pipe heat exchanger.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.17 no.2
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• pp.30-41
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• 2021

This paper presents the heating performance analysis results of a heat pump system using a dual heat source. In this paper, a dual heat source refers to the ground-coupled heat exchanger using both a surface water heat exchanger (SWHE) and a vertical ground heat exchanger (VGHE). In order to evaluate the system performance, we installed a monitoring system to measure the temperature and power consumption of a heat pump and then collected operation data with 4 different load burdened ratios of the dual heat source heat exchanger. During the whole measurement period, the average heating capacity of a water-to-water heat pump unit was 37.3 kW. In addition, the compressor of the heat pump consumed 9.4 kW of power, while the circulating pump of the dual heat source heat exchanger used 6.7 kW of power. Therefore the average heating coefficient of performance (COP) for the heat pump unit was 4.0, while the entire system including the circulating pump was 2.7. Finally, the parallel use of SWHE and VGHE was beneficial to the system performance; however, further researches are needed to optimize the design data for various load ratios of the dual heat source heat exchanger.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.2
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• pp.94-100
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• 2022

A study was conducted to significantly increase the heat transfer area by simultaneously burying the excel pipe in the floor and wall of a container house, thereby greatly reducing the initial heating time. In addition, a small hot water boiler suitable for the heating load of a small container house with a maximum area of 6 m² was studied. A wall-mounted hot water boiler was developed as a result of the study. When a hot water boiler is installed outdoors for heating, heat radiation energy is lost in winter from the hot water boiler and hot water pipe due to the low temperature. We propose an approach through which the energy loss was greatly reduced and the temperature of hot water increased in proportion to the operating time. Moreover, as the mass flow rate of the hot water flowing inside the excel pipe increased, the temperature of the hot water decreased. The temperature of the wall and floor surfaces of the container house increased in proportion to the increase in the mass flow rate of hot water flowing inside the excel tube. Natural convection heat transfer was realized from the wall and floor surfaces of the container house, and the heat transfer area was increased by a factor of 3 with respect to heat transfer area limited to the floor by the existing hot water panel. As a result, the initial temperature increase rate was much higher because of the larger heat transfer area.