• 설비공학논문집
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• 제29권4호
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• pp.167-174
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• 2017

This study attempted to investigate the value of photoelectric sensors in terms of a defrost-control method. Tests were conducted in a calorimeter room under the heating with the defrost-performance test conditions described in KS C 9306. Accordingly, the photoelectric technology is a competitive defrost-control method that can precisely control the operational defrost cycle using the output voltages that are proportional to the frost height. The heating period is gradually reduced because the complex defrost-control method, for which the sensors initiate the defrosting process and the defrosting process is terminated by the time parameter, could not adjust the net defrosting time by itself. Therefore, a complex defrost-control method, for which the photoelectric sensors start the defrosting process and it is terminated by the temperature parameter, is preferred because of the adjustment of the net defrosting time. Regardless of the defrost-control method, the first defrosting cycle is activated earlier than the times that are determined in the second and third cycles and so on, because the first operation cycle can decide the characteristics of the subsequent cycle.

• Journal of Acupuncture Research
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• 제15권2호
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• pp.173-182
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• 1998

In order to evaluate calorie rate of moxa-combustion(direct moxibustion=DM, indirect moxibustion with stainless steel tube=IMS, indirect moxibustion with ginger slice=IMG), calorie rate(%) in the preheating period, heating period, retaining period, and cooling period was calculated respectively to the total combustion calories in all the periods. The result are as follow: 1. Indirect moxibustion with stainless steel tube had the highest rate with the statistical significance than other groups during the preheating period, represented statistical differences between IMS group and IMG group, and also between DM group and IMS group. 2. Indirect moxibustion with ginger slice group showed the highest rate with the statistical significance and followed by DM group and IMG group during the heating period, represented statistical difference among DM, IMS, and IMG group. 3. Direct moxibustion group had the highest rate with the statistical significance than other group during the retaining period, represented statistical difference between DM group and IMG group, and also between DM group and IMS group. 4. Indirect moxibustion with stainless steel tube had the highest rate with the statistical significance than other groups during the cooling period, represented statistical differences between IMS group and IMG group, and also between IMS group and DM group.

• 한국농공학회논문집
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• 제58권5호
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• pp.71-79
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• 2016

The effects of spot heating for growing the strawberry cultivated in a plastic greenhouse during the winter that were estimated in Nonsan strawberry experiment station located in Chungnam. The temperature of water for heating was controlled by a electric hot water boiler and kept at the range of $22{\sim}24^{\circ}C$. Heating pipes were set up in root zone for root zone heating and very close to crown for crown heating. Spot heating effects were estimated by applying spot heating system in three test factors of heating root zone, crown only and crown plus root zone. The material for crown heating pipe was white low density polyethylene and the nominal diameter of that pipe was 16 mm. The material for root zone heating pipe was flexible stainless steel and the nominal diameter of that pipe was 15A. The flow rate of heating water circulation was 480 L/h and water circulation lasted for all day long. Temperatures, harvest yield by test beds were surveyed from Nov. 10, 2013 to Apr. 29, 2014. The temperature of crown spot for crown heating bed was at the range of $13.0{\sim}17.0^{\circ}C$ during the night and that of crown spot in control bed was at the range of $8.0{\sim}14.0^{\circ}C$. Also, the temperature of root zone for root zone heating bed was at the range of $18{\sim}21.0^{\circ}C$ and that of root zone in control bed was at the range of $13.0{\sim}15.0^{\circ}C$. The cumulative yield growth rate in earlier harvest period (from Dec. 20 to Mar. 15) of crown heating bed was 43% compared with that of control bed and the cumulative yield of crown plus root zone heating bed was 39 % and that of root zone heating bed was 39 %.

• 한국식품영양학회지
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• 제28권6호
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• pp.1033-1044
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• 2015

조선시대 김치는 재료를 가열하여 담그는 김치가 많았다. 소금이 비쌌기 때문에 소금과 시간을 절약하기 위하여 채소를 가열하여 세포벽을 파괴하는 방법을 사용한 것이다. 그러나 현재는 맥이 끊겨 있기 때문에 본 논문에서 조선시대 김치 조리서를 분석하여 가열하여 담그는 김치를 밝혔다. 그 결과, 재료를 데쳐서 담그는 김치는 27가지였다. 김치가 무르는 것을 방지하기 위하여 재료를 백반물에 담그는 김치는 2가지, 재료를 석회물에 데쳐서 담그는 김치는 3가지였다. 재료를 식초로 가열하여 담그는 김치는 7가지, 재료를 삶아서 담그는 김치는 5가지, 재료를 볶아서 담그는 김치는 6가지, 재료를 소금에 볶아서 담그는 김치는 2가지, 재료를 쪄서 담그는 김치는 3가지였다. 잡균을 죽이고 유산균만 잘 번식하게 하기 위하여 끓인 담금액을 부어서 담그는 김치는 25가지였다. 말똥이나 두엄으로 김칫독을 가열하여 숙성시키는 김치는 17가지였다. 치아와 소화력이 좋지 않은 노인을 위한 익혀 담그는 김치는 7가지였고, 그 중 3가지가 숙깍두기였다. 노인용 김치인 채김치 3가지와 채깍두기 3가지도 있었다.

• 설비공학논문집
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• 제6권3호
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• pp.315-324
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• 1994

The energy recovery efficiency(ERE) of an aquifer thermal energy storage system was calculated using curvilinear coordinate. The results of the calculation were compared with the experimental results, and agreed within 11% of the discrepancy. The variation of ERE was investigated as a function of the underground water natural velocity, the amount of the stored energy, and period of the energy recovery. The slower the natural velocity and shorter the recovery period, the higher ERE was yielded. Also it was found that increase in the amount of energy storage yields higher ERE, and carries out less influential ERE to the natural velocity. Reiterative usage of the aquifer as a thermal storage tends to gradually increase ERE. The result of this study implements that the aquifer thermal energy storage system is suitable for large cooling/heating loads, such as district cooling/heating.

• 한국태양에너지학회 논문집
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• 제32권5호
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• pp.11-17
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• 2012

In this study, a simulation program was developed with heat transfer model in the thermal storage tank for a solar collector and burner combined heating and hot water supply system. Analysis was conducted with variation of operating condition and schedule to analyze performance of a hot water supply and panel heating system with a solar collector and burner combined thermal storage tank. The simulation program is divided two sections. One part is calculation of temperature variation of water which flows through the panel in the floor for heating of the residential house during 24 hours, and the other part is heat transfer calculation for the reaction time to get desired water temperature in the thermal storage tank. As results, light oil consumption and system performance during operation period were analyzed with variation of climate condition and with or without solar collector. Most of the case, oil could be saved about from 24 to 41% with installing the solar collector. The performance of the system is more dependent on radiation time of the solar collector rather than the intensity of the solar radiation which was adopted for the climate analysis.

• Advances in materials Research
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• 제4권1호
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• pp.13-22
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• 2015

Concrete suffers strength loss when subjected to elevated temperatures during an accidental event such as fire. The loss in strength of concrete is mainly attributed to decomposition of C-S-H gel and release of chemically bound water, which begins when the temperature exceeds $500^{\circ}C$. But it is unclear about how much strength loss occurs in different stages of heating, retention and cooling regimes. This work is carried out to separate the total strength loss into losses during different stages of heating, retention and cooling. Tests were carried out on both Ordinary Portland Cement (OPC) based concrete and Ground Granulated Blast Furnace Slag (GGBFS) blended concrete for $200^{\circ}C$, $400^{\circ}C$, $600^{\circ}C$ and $800^{\circ}C$ with a retention period of 1 hour for each of these temperature levels. Furnace cooling was adopted throughout the experiment. This study reports strength loss contribution during heating, retention and cooling regimes for both OPC based and GGBFS based concretes.

• 한국지열·수열에너지학회논문집
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• 제16권3호
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• pp.8-16
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• 2020

This paper presents the heating performance analysis results of a ground-source heat pump (GSHP) system using hybrid ground heat exchanger (HGHE). In this paper, the HGHE refers to the ground heat exchanger (GHE) using both a surface water heat exchanger (SWHE) and a vertical GHE. In order to evaluate the system performance, we installed monitoring sensors for measuring temperatures and power consumption, and then measured operation data with 4 different load burdened ratios of the HGHE. During the entire measurement period, the average heating capacity of the heat pump was 37.3 kW. In addition, the compressor of the heat pump consumed 9.4 kW of power, while the circulating pump of the HGHE used 6.7 kW of power. Therefore, the average heating coefficient of performance (COP) for the heat pump unit was 4.0, while the 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 HGHE.

• Journal of Acupuncture Research
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• 제18권6호
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• pp.171-187
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• 2001

Objective : Moxibustion has been proved efficacious for many diseases, but isn't widespread in the clinics due to a danger of skin burning, the smoke produced while burning a moxa combustion and so on. Therefore, another type of moxa that can be resolved these troubles is required. To improve the effect of moxibustion and develop the new thermal stimulating treatment, the performance of commercial moxibustion widely used are studied systematically and found out quantitatively. Methods : We have selected two types (small-size moxa A(sMA), small-size moxa B (sMB)) among small-size moxaes used widely in the clinic. We examined combustion time, various temperatures, temperature gradient in each period during a combustion of moxa. Results : 1. The combustion time in the preheating period appeared somewhat longer in sMA than in sMB. 2, The combustion time in the heating period appeared longer in sMA by 26% than in sMB. 3. The average temperature in the heating period was $37.6{\sim}37.8^{\circ}C\;in\;sMA\;and\;36.2{\sim}36.8^{\circ}C$ in sMB and the maximum temperature measured at a center of contact surface in sMA was $48.6^{\circ}C$, higher by over $2.8^{\circ}C$ than that of sMB moxibustion. 4. The average ascending temperature gradient in the heating period was $0.08{\sim}0.1^{\circ}C/sec$ in both moxaes, and the average ascending temperature gradient of heating period in sMB appeared larger. The maximum ascending temperature gradient appeared higher in sMB, and the time reaching maximum ascending temperature gradient appeared much earlier in sMA than in sMB. 5. The combustion time in the retaining period was around 100 sec in sMA and around 275 sec in sMB. 6. The average temperature in the retaining period was $42.2{\sim}46.0^{\circ}C\;in\;sMA\;and\;39.3{\sim}41.4^{\circ}C/sec$ in sMB. The minimum temperature in the retaining period was over $38.80^{\circ}C$ in sMA but just $34.7^{\circ}C$ in sMB. 7. The average descending temperature gradient in sMA was $-0.050{\sim}0.067^{\circ}C/sec$ and in sMB was $-0.030{\sim}0.037^{\circ}C/sec$ 8. The combustion time in the cooling period appeared longer over two times in sMA than in sMB, and the time which the cooling period (minimum temperature) finished at appeared later in sMB by 55 sec. 9. We classified the combustion process that the measured temperature rose over body heat($37^{\circ}C$) into the effective combustion period. The effective combustion time was 233.3 sec in sMA and 300.4 sec in sMB respectively, and was longer by about 29% in sMB. The average temperature and maximum temperature in the effective combustion time appeared higher in sMA. The time taken until the maximum temperature was reached was 225.1 sec in sMA and 244.5 sec in sMB, faster by about 20 sec in sMA. The maximum ascending temperature gradient during the effective combustion period appeared larger about 1.4 times in sMB, but the time when the maximum ascending temperature gradient happened was faster in sMA. Conclusion : It appears that sMB, compared with sMA, is proper if necessary to apply the long time and weak stimulus, because of the gentle stimulus during the relatively longer time. In contrast, sMA that the symmetrical combustion happened is proper if necessary to apply the short time and strong stimulus.

• 설비공학논문집
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• 제27권1호
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• pp.31-38
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• 2015

Geothermal heat pump (GHP) systems have become an efficient alternative to conventional cooling and heating methods due to their higher energy using efficiency. These systems use the ground as a heat source in heating mode operation and a heat sink in cooling mode operation. The aim of this study is to evaluate the heating performance of the GHP system for a residential building ($420m^2$) in Ulaanbaatar, Mongolia. In order to demonstrate the feasibility of a sustainable performance of this system, we installed the water-to-water geothermal heat pump with ten vertical ground heat exchangers and measured operation parameters from October 19, 2013 to March 26, 2014. The results showed that the entering source temperature of brine from the ground heat exchangers was in a range of the design target temperature of $-10^{\circ}C$ for heating. For total values of the representative results, the ground heat exchangers extracted heat of 53.51 MWh from the ground. In addition, the GHP system supplied heat of 83.55 MWh to the building and consumed power of 30.27 MWh. Consequently, the average heating seasonal performance factor ($SPF_h$) of the overall system was evaluated to be 2.76 during the measurement period of the heating season.