• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.2
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• pp.183-189
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• 2012

Most of the domestic residential buildings have used the traditional radiant heating system, circulating hot water through the cross-linked polyethylene(PE-X) pipe buried in the floor panel of the heating space. New type of the heating panel was recently developed using heat pipes with double wicks. Some experiments were carried out in this study to verify the thermal characteristics of this heating system at the unit heating space which surrounded by outer space whose temperature of air be maintained scheduled value with time. Through the various experiments with several parameters, such as flow rate, inlet and outlet temperatures of hot water and the heating duration and so on, we found that the floor heating system with heat pipes was able to reduce the pumping power for hot water circulation by 4~31% compared with the conventional panel heating system using PE-X pipe. These results could be used for optimal design and efficient operation of the heating system as well as improvement of thermal comfort.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1446-1448
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• 2002

The short-time permissible temperature of an overhead distribution line conductor is determined by the softening characteristics of ACSR-OC, ACSR AW/OC 160, typical conductors employed in the overhead distribution line. Transient heat transfer equation and Newton's cooling law were applied to analyze the heating and cooling effects of the insulating conductors, respectively, and the error of co-relation was calibrated after simulating the softening test to assess the short-time characteristic of the insulating conductor. In order to verify the softening characteristic, the conductors were tested with heat cycle. The test was totally carried out 200 cycles, and 1 cycle was to heat and cool at 1.1 times permissible current of the conductor, 1.15 times for 120 minutes, respectively. After heating, the tensile strength and surface of the conductor were observed. In case of ACSR-OC, as the result of 100 hour heating test, the tensile strength of the insulator was 0.8 times the initial value. This is equivalent to the value of the conductors which are used for 10 years at sites.

• Journal of the Korean Society of Food Science and Nutrition
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• v.23 no.5
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• pp.822-826
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• 1994

Effects of concentration(6-9%, db) , heating temperature (80-95$^{\circ}C$), cooking time (10-50min) and heating method (continuous and instantaneous) on the apparent viscosity of cowpea sediment dispersions at 6$0^{\circ}C$ were investigated. The instantaneous heating resulted in higher apparent viscosity than continuous heating regardless concentrations and heating temperatures. The activation energy of the increase rate constant of the apparent viscosity was about 8 kcal/mole. The apparent viscosity of the cowpea sediment dispersion heated to 95$^{\circ}C$ and held for 20 min showed a linear relation with the 20 min height at 92.5$^{\circ}C$ by viscoamylograph.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.11a
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• pp.177-180
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• 2012

Korea residential housing generally use wet floor heating system 'Ondol' which consist of insulation cushioning, lightweight foamed concrete, hot water pipe and mortar on top of reinforced concrete slab. Wet floor heating system's installation process is too complicate and difficult to supervise field for continuing assurance quality. Also, this method has a huge impact on the progress of construction because it take a long time to cure finishing mortar and lightweight foamed concrete. Therefore, it is considered a disturbance factor of reduction of construction duration for enhancing competitiveness. In this study, we conducted an experiment about the radiant heat performance and temperature difference on upper panel of rolled dry floor heating systems which is jointly developed by Kolon global and Sumisho Metalex for remodeling housing, studio apartment and the urban-life housing.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.709-712
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• 2001

The effects of post annealing temperature by the Rapid Thermal Annealing(RTA) on the electrical properties of Pb(Zr,Ti)O$_3$(PZT) thin film were investigated. Analyses by the RTA treatments reveled that the leakage current of PZT thin films strongly depend on heating temperature and time. It was found that leakage current properties of PZT capacitor were changed by heating temperature during the RTA annealing. On Pt/Ti/Si substrates, PZT films are deposited at 350 $^{\circ}C$ by rf magnetron sputtering. The X-ray diffusion (XRD) was confirmed the formation of PZT thin film. Leakage current characteristics were improved with decreasing the post annealing temperature of PZT thin film. RTA annealed film on the 700$^{\circ}C$ shows ferroelectric and electrical properties with a remanent polarization of 12.4${\mu}$C/$\textrm{cm}^2$ coercive field of 117kV/cm, leakage current J= 6.2${\times}$10$\^$-6/ A/$\textrm{cm}^2$

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2254-2255
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• 2008

Thermoforming is one of the most versatile and economical process to produce polymer products. The drawback of thermoforming is difficult to control thickness of final products. Temperature distribution affects the thickness distribution of final products, but temperature difference between surface and center of sheet is difficult to decrease because of low thermal conductivity of ABS material. In order to decrease temperature difference between surface and center, heating profile must be expressed as exponential function form. In this study, Finite Difference Method was used to find out the coefficients of optimal heating profiles. Through investigation, the optimal results using Finite Difference Method show that temperature difference between surface and center of sheet can be remarkably minimized with satisfying Temperature of Forming Window.

• The Korean Journal of Food And Nutrition
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• v.28 no.1
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• pp.126-133
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• 2015

Ohmic heating uses electric resistance heat which occurs equally and rapidly inside food when the electrical current is transmitted into. Prior to the study, we have researched the potato starch's thermal property changes during ohmic heating. Comparing with conventional heating, the gelatinization temperature and the range of potato starch treated by ohmic heating are increased and narrowed respectively. This result is appeared equally at wheat, corn and sweet potato starch. At this study, we treated potato, wheat, corn and sweet potato starch by ohmic/conventional method and observed change of external structure by microscope and internal structure by X-ray diffractometer. Conventional heated at $55^{\circ}C$ potato starch was not external structural changes. But ohmic heated potato starch is showed largely change. Some small size starch particle were broken or small particles are made of larger particle together or small particles caught up in the large particle. Changes in ohmic heated potato starch at $60^{\circ}C$ was greater. The inner matter came to an external particle burst inside and only the husk has been observed. The same change was observed in the rest of the starch. The change of internal structure of potato starch was measured using X-ray diffraction patterns. There was no significant difference between ohmic and conventional heating at $55^{\circ}C$. But almost every peak has disappeared ohmic at $60^{\circ}C$. Especially $5.4^{\circ}$ peak to represent the type B was completely gone. When viewed from the above results, external changes with change in the internal crystal structure of the starch particles were largely unknown to appear. In conclusion, during ohmic heating changes of starch due to the electric field with a change in temperature by the heating was found to have progressed at the same time.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.04a
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• pp.140-141
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• 2022

CFD analysis was performed to analyze the temperature distribution of the inner space of the curing house according to blocking the opening of the gang-form with a tent in case of concrete pouring and heat curing of the apartment house during the winter season. If the gang-form opening is closed with a tent during internal heating using a hot air blower in the winter, the internal temperature rises compared to the non-reserved due to air-tightness of the curing spaces, and uniform temperature distribution can be ensured. In addition, it is possible to increase curing efficiency by reducing the amount of heat supplied and shortening the heating time.

• 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 Society of Food Culture
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• v.23 no.1
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• pp.26-32
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• 2008

: In this experiment, three samples of oils were used. These oils were hydrated soybean oil, pure soybean oil and regular soybean oil. Oil was used after heating at $235-240^{\circ}C$ every four hours term and total heating hours was 16 hours. The physio-chemical analysis and sensory evaluation were performed on these oils. The hydrated soybean oil showed lower acid, peroxide and carbonyl value than the other two oils (p<0.05 or p<0.001). The other two oils were more affected in rancidity than the hydrated soybean oil. In color test, whereas L value lowed during the heating time, a and b value increased during the heating time. The tendency of high L value and low b value in a long-time heating was more apparant on the pure soybean oil and the regular soybean oil than on the hydrated soybean oil (p<0.05). In sensory evaluation, color and rancidity order increased during the heating time. The hydrated soybean oil showed color and rancidity order than the other two oils. In overall quality test, the pure and regular soybean oil that had been used for 12 and 16 hour were not preferable. The hydrated soybean oil that had been used for 16 hour were not preferable. In sensory evaluation, the hydrated soybean oil, the pure and regular soybean oil did not show a apparent difference, although the hydrated soybean oil had a little better scores on the overall quality.