• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.11a
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• pp.155-156
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• 2018

In this study, surface spalling and explosive spalling of ring-type ultra-high strength concrete under rapid heating and slow heating were investigated. In rapid heating, the internal temperature difference of the concrete is large, so that continuous surface spalling occurs. However, in slow heating, the difference in the internal temperature of the concrete is small, resulting in explosive spalling at a time. Since the heating condition has a great influence on the internal temperature of the concrete, it is necessary to consider the spalling of the concrete under various heating conditions.

• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.381-386
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• 2008

In this study, the energy characteristic of automatic thermostatic valves according to each heating method in floor radiant heating system were researched by computer simulation. For the analysis of unsteady heat transfer phenomena in household, the method of using electrical equivalent R-C circuit is applied, and radiation heat transfer between panel, ceiling and walls in household is calculated by enclosure analysis method. The parametric study on heating method, valve's control method, outdoor air condition, supply heating water temperature, supply flow rate are performed to compare energy characteristic, respectively.

• New & Renewable Energy
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• v.1 no.2 s.2
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• pp.53-59
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• 2005

Objective of the research is to demonstrate solar thermal space and ground heating system which is integrated to a green-house culture facility for reducing healing cost, Increasing the value of product by environment control, and developing advanced culture technology by deploying solar thermal system. Field test for the demonstration was carried out in horticulture complex In Jeju Island. Medium scale solar hot water system was installed in a ground heating culture facility. Reliability and economic aspect of the system which was operated complementary with thermal storage and solar hot water generation were analyzed by investigating collector efficiency, operation performance, and control features. Short term day test on element performance and Long term test of the whole system were carried out. Optimum operating condition and its characteristics were closely Investigated by changing the control condition based on the temperature difference which Is the most important operating parameter For establishing more reliable and optimal design data regarding system scale and operation condition, continuous operation and monitoring on the system need to be further carried out. However, It is expected that, in high-insolation areas where large-scale ground storage is adaptable, solar system demonstrated in the research could be economically competitive and promisingly disseminate over various application areas.

• Journal of Power System Engineering
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• v.18 no.2
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• pp.50-56
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• 2014

Friction welding is a very useful joining process to weld metals which have axially symmetric cross section. In this paper, for the friction welding with tube-to-tube shape, the feasibility of industry application was determined using analyzing mechanical properties of weld and optimized welding variables was suggested. In order to accomplish this object, rotating speed, friction heating pressure, and friction heating time were selected as the major process variables and the experiment was performed in three levels of each parameter. Weld characteristic was investigated in terms of weld shape and metal loss, and 7mm of metal loss was regarded as the optimal metal loss. By tensile test, tensile strength and yielding strength was measured and fracture was occurred at base metal. In order to optimize the welding condition, fitness function was defined with respect to metal loss and yielding strength and the fitness values for each welding condition could be calculated in experimental range. Consequently, we set the optimal welding condition as the point which had maximum value of fitness function. As the result of this paper the optimal welding variables could be suggested as rotating speed was 1300 rpm, friction heating pressure was 15 MPa, and friction heating time was 10 sec.

• The Korean Journal of Food And Nutrition
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• v.16 no.2
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• pp.130-137
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• 2003

The squid had not been utilized for gel products because of its lower gel forming ability. The objectives of this study were as followed; 1) the optimum heating condition on squid meat paste products and 2) the optimum added level for jelly strength of squid meat paste products. Optimum heating conditions of squid meat kamaboko were as followed; setting(pre-heating) at 15$^{\circ}C$ or 55$^{\circ}C$ for 2 hours and heating at 9$0^{\circ}C$ for 60 minutes. The additives examined were as follows; 20mM EDTA, 10mM PMSF, 5 $\mu$mol/100g TGase, 0.2% potassium bromate, 2% collagen, 2% sucrose ester of stearic acid and 1% egg shell powder. The effects of additives on jelly strength were observed as follow, in descending order; 10mM of PMSF>5 $\mu$mo1/100g of TGase>0.2% of potassium bromate>20mM of EDTA. But sucrose ester of stearic acid and 1% egg shell powder were no effect. The solvents examined were as follows; n-amyl alcohol, n-butyl alcohol, n-hexyl alcohol, ethyl alcohol, ethylene glycol, propylene glycol and glycerin glycol. It showed that high jelly strength as 787gㆍcm for 3% of n-butyl alcohol and 749gㆍcm for 3% of n-amyl alcohol. To adding 5% of n-butyl alcohol and n-amyl alcohol, gave the highest jelly strength and water holding capacity(WHC). Effect of alcohol on jelly strength appeared higher value at added 5% of n-butyl alcohol than n-amyl alcohol, and flying squid product was higher than jumbo squid product.

• Journal of The Korean Society of Agricultural Engineers
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• v.50 no.1
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• pp.39-47
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• 2008

Most of the broiler houses in Korea have experienced problems on controlling the environmental conditions such as suitability, stability and uniformity of rearing condition inside the broiler house. It is very critical which if not properly controlled, would cause serious stress on the chickens. It is therefore urgent to develop optimum designs of naturally ventilated broiler house which is appropriate to the four seasons of Korea. Field experiment for this matter is very difficult to conduct due to the unpredictable and uncontrollable weather condition. In this study, the heating load of a naturally ventilated broiler house was calculated using TRANSYS 15 BES program while internal climate and thermal condition were computed using Fluent 6.2. The computed resulted of the conventional ventilation system (A) and upgraded ventilation system (B) (Seo et al, 2007) were compared with each other for cold season. The results of the Building Energy Simulation(BES) indicated that the system B, the upgraded ventilation system made 8% lower total heating load and 47% lower at only the broiler zone compared to the conventional broiler house. Considering the entire broiler house, the existence of middle ceiling made the heating energy 11% lower required than without middle ceiling. Accordingly, the system B with middle ceiling was found to save heating energy by 20% in average. This study showed that the BES program can be a very powerful to effectively compute the energy loads of agricultural building while the energy load is very close related to ventilation efficiency.

• Journal of Environmental Science International
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• v.13 no.3
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• pp.189-196
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• 2004

Characteristics of urban wanning phenomenon were studied using degree days for three big cities(Seoul, Busan, Daegu) adjacent to airport. Time variation of the cooling and heating degree days was analyzed using the daily mean air temperature data measured at the six meteorological observatory for long-term periods(25～43years). The results for the big cities are as followings: 1) It was found that the heating degree days trended to decrease from year to year. 2) The cooling degree days were nearly unchanged during the same analysis periods. 3) The number of days calling for air-heating also tended to decrease as time passes. 4) Those of air-cooling were nearly unchanged during the same time. It suggests that the change of air-heating condition owing to urbanization came in evidence in the winter season, but that of air-cooling condition was slight in the summer season. On the other hand, the long-term trends of degree days were very small in airport areas except for Kimhae airport. Hence, the gaps of degree days between big cities and rural airport areas are increasing.

• Journal of the Korean Solar Energy Society
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• v.32 no.5
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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.

• Fire Science and Engineering
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• v.20 no.3 s.63
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• pp.113-117
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• 2006

This study presents analysis of fire hazard of electrical heating pad. In order to analyze fire hazard fire experimental and flammability experiment is conducted. The fire experiment is conducted to simulate normal condition and abnormal condition such as breakdown of thermostat. Vertical burning test(UL 94) is conducted for the fire retardant experiment. Kinds of electric heating pad used for experiment are electric mat, fabric pad, vinyl pad. The results show that fire hazard is high in case of breakdown of thermostat with the rating voltage supply. And Material of electric heating pad has not fire retardant performance.

• Aerospace Engineering and Technology
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• v.2 no.2
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• pp.83-88
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• 2003

Satellite mounted on the launch vehicles experiences several environmental heating, such as direct solar flux, Earth IR, Albedo, and free molecular heating during faring jettison-separation launch stage. So, the most outer payload box of satellite is under the worst hot condition. The thermal governing equation is reduced into 1st order ordinary differential equation and analytic solution is acquired if payload box is assumed as a single lumped mass. Applying the analytic solution, we can predict the temperature increase of payload box experienced the worst hot condition, easily.