• Journal of the Korean Society of Combustion
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• v.20 no.4
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• pp.19-25
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• 2015

An experimental study was conducted to find the effect of a pilot flame on the flammability of inert-gas-diluted methane and propane. The diffusion pilot flame was formed with propane at the innermost nozzle of a concentric triple co-flow burner. The main diffusion flame was formed with nitrogen-diluted methane or propane at the outermost nozzle of the burner. An air flow was located in-between. The results showed that the existence of the pilot flame helped stabilizing the main flame even at the flammability limit concentration of nitrogen-diluted fuel. The co-flow burner generated re-circulation zones and local variation of equivalence ratio depending on the flow rates of the reactants, which are known to help flame stabilization. Hot-wire experiments confirmed that both heating of the reactants and supplying of active chemical species by the pilot flame contributed to stabilization of the main flame. The results of this study would suggest a design concept for an efficient SVRU system that minimizes the emission of unburned hydrocarbon fuel from ship fuel tanks.

• International Journal of Aeronautical and Space Sciences
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• v.3 no.1
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• pp.95-104
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• 2002

Numerical solution of the full Navier-Stokes equation as well as the energy equation has been obtained for the unsteady natural convection in a rectangular enclosure. One side wall was maintained at very high temperature simulating fires. Especially the effect of surface radiation was taken into account. While the enclosed air was assumed to be transparent, the internal walls directly interacted one another through the surface radiation. Due to a significant temperature difference in the flow field, the equation of state was used instead of the Boussinesq approximation. It was found that the rapid heating of the adiabatic ceiling and floor by the incoming radiation from the hot wall made the evolution at thermo-fluid field highly unstable in the initial period. Therefore, the secondary cells brought about at the floor region greatly affected the heat transfer mechanism inside the enclosure. The heat transfer rate was augmented by the radiation, resulting in requiring less time for the flow to reach the steady state. At the steady state neglecting radiation two internal hydraulic jumps were clearly observed in upper/left as well as in lower/right comer. However, the hydraulic jump in the lower/right comer could not be observed for the case including radiation due to its high momentum flow over the bottom wall. Radiation resulted in a faster establishment of the steady state phenomena.

• Journal of the Korean Wood Science and Technology
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• v.22 no.2
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• pp.61-70
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• 1994

This study was executed to find the applicability of press drying of tree disk by investigating the shrinkage and drying defect and to form appropriate model by comparing the actual moisture content(MC) and internal temperature in respect of drying time with calculated values based computer simulation to which was applied finite difference method. In press drying disk, heating period, constant drying rate period maintained plateau temperature at 100$^{\circ}C$ and falling drying rate period were significantly distinguished. Actual MC and internal temperature were analogous to those calculated at comparing points. Heat transfer model formed by Fourier's law using specific heat of moist wood and conduction coefficient considering fractional volume of each element of wood cell wall, bound water, free water and air showed applicability as basic data to developing heat expansion, shrinkage and drying stress during press drying. Also mass transfer model formed by Fick's diffusion law using water vapor diffusion coefficient showed applicability. Longitudinal shrinkage was developed by pressure of hot press and tangential shrinkage was restrained by hygrothermal recovery. The heart check, surface check and ring failure were occurred differently in species, but V-shaped crack didn't develop.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.17 no.5
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• pp.361-367
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• 1984

In previous paper(Lee et al., 1984), preparation formula and processing conditions of the fish meat (mackerel) paste using dielectric heating were described, that included the proper shape and size of product and the conditions of dielectric heating, hot air dehydration, and heating with electric heater to yield the minimum expansion and case hardening during heating and to controll the final rater activity of 0.86 to 0.83 accompanying with a complete reduction of viable cells and good texture. In present study, changes in VBN, pH, total plate count, water activity, texture, the loss of available lysine, color indexes, TBA value, and the content of TI were determined to assess the quality stability and shelf-life of the product during the storage for 35 days at $5^{\circ}C\;and\;25^{\circ}C$, respectively. And the effect of vacuum sealing and hot water treatment before storage on the storage stability of product was also mentioned. As the product was vacuum packed in K-flex film bag, heat treated in boiling water for 6 minutes, and stored, water activity was maintained 0.86 to 0.84 for 35 days regardless of storage temperature, and the increase of total plate count was negligible in case of $5^{\circ}C$ storage while tended to gain slightly after 25 days at $25^{\circ}C$ storage. Changes in VBN was also minimum with an increase of 1.5 mg/100g at $5^{\circ}C$ and 7.0mg/100g at $25^{\circ}C$, but in case of unpacked sample, it was 24.5mg/100g at $5^{\circ}C$ and 42.4 mg/100g at $25^{\circ}C$ even after 7 days. In textural property hardness tended to increase after 28 days and folding test score was down to A or B from AA grade. The loss of available lysine was $7.5\%\;at\;5^{\circ}C$ and $17.0\%\;at\;25^{\circ}C$ but brown color was not deeply developed as the color index score indicated. TBA value was not increased at $5^{\circ}C$ while it tended to increase rapidly after 30 days at $25^{\circ}C$. Changes in TI content was not obvious except that it showed a tendency of increase at the end of storage as well as in the change of lysine and TBA value. It is concluded from the results that the quality of the product, pasteurized and water activity controlled by dielectric heating, and vacuum packed in K-flex film would be stable for more than 35 days at $5^{\circ}C$ and at least 25 days even at room temperature.

• Journal of Bio-Environment Control
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• v.22 no.3
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• pp.270-278
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• 2013

The objective of the present study is to provide data needed to decide covering method to be able to increase the thermal insulation and light transmittance efficiency of commercial greenhouse. The thermal insulation effect, PPF transmittance and quantity of condensation water were estimated in experimental tomato greenhouses covered with three types of coverings of single layer, air inflated and conventional double layers covering. The overall heat flow of air inflated double layers greenhouse was similar to that of conventional double layers greenhouse, but the temperature between covering material and thermal screen in air inflated double layers greenhouse was lower than that in conventional double layers greenhouse at the same outside temperature condition due to air leakage through the gap of roof vent. The overall heat transfer coefficients acquired by experiment that was performed in single layer and conventional double layers greenhouses were close to those obtained from model experiment. Even though the PPF transmittance of air inflated double layers greenhouse was lower than that of single layer greenhouse, which was greater than that of conventional double layers greenhouse. The quantity of condensation water on covering surface of single layer greenhouse was greater than that of air inflated double layers greenhouse due to lower covering surface temperature.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.299-303
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• 2008

The treated sewage temperature is about $5^{\circ}C$ lower in summer and $5{\sim}10^{\circ}C$ higher in winter than ambient air. It can be used heat pump heat source and is good heat source on high performance of heat pump. In this study, to develop 100RT 2-stage compression heat pump use treated sewage water heat source and system applies to sewage disposal plant. Although heat pump is better performance, the large temperature difference between load and source makes the performance degradation of a heat pump. To solve this problem screw 2-stage compression is considered. The experiment was focused on the system operating performance variations over supply water and treated sewage water a temperature in the field. The results show that system of heating performance is higher then general heat pump and is enough to supply a hot water of $70^{\circ}C$.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.29 no.3
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• pp.111-118
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• 2017

Performance factors such as the EER(Energy Efficiency Ratio) and the COP (Coefficient of Performance) are being replaced by seasonal energy efficiency factors, like the SEER (Seasonal EER) and the SCOP (Seasonal COP) to evaluate the performance of a heat pump by the time of the year. Seasonal performance factors, such as the CSPF (Cooling Seasonal Performance Factor) and the HSPF (Heating Seasonal Performance Factor) are used to describe the heat pump's performance during the cool and hot seasons. In this study, the optimization of all heat pump's operating parameters was experimentally conducted to enhance the SEER based on the EU standard (EN 14825). Moreover, the SEER was improved by the compressor frequency, as well as indoor and outdoor fan speeds. In addition, the performance characteristics of the heat pump were studied under partial load conditions. As a result, the SEER was enhanced by 17% when the compressor frequency was optimized. An additional 2% improvement was achievable with the optimization of indoor and outdoor fan speeds.

• Journal of the Korean Solar Energy Society
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• v.30 no.6
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• pp.28-33
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• 2010

Solar collectors to be applied are mainly flat-plate or vacuum tube collector which is used for hot water supply of house because of low heat value and low temperature. There are a necessity to expand applicable scope of solar collector into the industrial process heat source and air conditioner for coping with renewable energy policy of government and industrial trend. This study is to analysis the performance of PTC solar collector of concentrating type and flat-plate of non-concentrating. For this, temperature difference and heating value as insolation of air outside is measured from these two collectors mounted on 2-axial solar tracking system. It is investigated that temperature profile obtained from PTC solar collector is uniform and collecting heat per unit area is 6.8kcal/$m^2$ min which is about 3 times with compare to flat-plate collector of 2kcal/$m^2$min. Also the amount of heat to be produced from PTC solar collector is 3 Mcal/$m^2$ which is about 2 times with compare to flat-plate collector of 1.5Mcal/$m^2$ as a result of operating these two collectors during one month. Therefore, it is obtained that heat collecting performance of PTC solar collector is superior to flat-plate.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.25 no.5
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• pp.225-232
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• 2013

Heat pump systems have been widely adopted in buildings for cooling and heating, due to their higher energy efficiency. Recently, the demand for hot water supply from the heat pump system has been increasing. To increase the water supply temperature with higher system efficiency and reliability, a heat pump water heater adopting cascade cycle was investigated in this study. The cascade heat pump water heater consisted of a low-stage cycle using R410A, and a high-stage cycle using R134a. A simulation program for the cascade heat pump water heater was developed, and verified by comparison with experimental data. The performance of the cascade heat pump water heater was optimized, by varying the compressor rotating speeds of the low- and high-stage cycles. At low ambient temperatures, the performance of the cascade cycle was compared with that of the single-stage cycle. The system efficiency of the cascade cycle was higher than that of the single-stage cycle, showing a lower compression ratio and compressor discharge temperature.

• Journal of Families and Better Life
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• v.23 no.2 s.74
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• pp.107-125
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• 2005

Each ethnic group has a different cultural background and has developed its own culture in the name of a tradition. The interaction between different cultures is ever increasing through the process of acculturation or culture contact The purpose of this study is to provide baseline information about domestic living of Korean immigrants in Australia and Australians for a larger cross-cultural study project. As the first step, the usage of domestic space and seating styles of 52 Korean households in Melbourne were analyzed. Ethnographic research was conducted, utilizing a questionnaire. The findings of this research are as follows: 1. The most popular type of Living-Dining-Kitchen arrangement was the one which the kitchen is separated from the living and dining area. The level of satisfaction was the highest when the living room, dining room, and kitchen were all separated. 2. A laundry room was indispensable for Koreans in Australia, and they wanted to dry laundry and do ironing in there. Most people were satisfied with the toilet separated from the bathroom A drain hole on the floor of the bathroom was not indispensable for most Korean-Australians. 3. Korean-Australians tend to engage in various activities in their individual rooms, and they estimated that the size of most rooms were small. They also wanted to renovate the house to expand the rooms. 4. The seating style of Korean-Australians was mostly chair-seating. Yet, they often made beds on the floor for guests, and made kimchi sitting on the floor. Also, when they were relaxing, they were using both chair-seating and floor-seating. 5. Korean-Australians were not very satisfied with the use of floor carpets because of the dust collected on the carpets, and the difficulty to clean. It may be related to their preferred floor seating style, as well. 6. Almost all Korean-Australians take off their shoes inside of the house for hygienic reasons. They had a shoes cabinet at the entrance inside of the house. 7. The most popular heating system was ducted heating. The level of satisfaction about this was moderate because hot air contains lots of dust and it makes rooms very dry. Many were using electric blankets and their desired heating system was Ondol (heated floor). 8. Korean-Australians thought that the living room was the most important place for the family, and believed it should be decorated well to entertain guests. They also pointed out that the lighting was not bright enough in general.