• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.12
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• pp.821-827
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• 2010

Study on the performance characteristics of the solar hybrid system with heat pump operating temperature during winter season has performed by using an experimental test. The system performance and operating characteristics with the heat pump operating temperature, hour and load condition were investigated and analyzed. As a result, the hot water temperature was significantly affected by the heat pump operating temperature at the morning(time 1) and noon(time 2). However, hot water temperature was set by the radiation quality and collecting operation hour at the afternoon(time 3). In addition to the solar fraction was decreased for the high heat pump operating temperature because the heat pump operated with a long operating time and short operating period.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.360-363
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• 2000

A half bridge type double resonant high frequency resonant inverter using PFM is described. This proposed inverter can reduce distribution of the switching current because of using the current of the serial resonant circuit to the input current of the parallel one. In the case of variable capacitance of the DC voltage source separated capacitor the analysis of inverter circuit has generally described by using normalized parameter and operating characteristics has been evaluated in terms of switching frequency and parameters. Based on the characteristics value a method of the circuit design is proposed. The theoretical results are in good agreement with the experimental ones. In the future this proposed circuit is considerated to be useful for induction heating and discharge lamp.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.10
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• pp.737-747
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• 2009

This study is to investigate the effect of the moisture, volatile matter and particle size in the coal on the pulverized coal combustion characteristics using CFD. The results show that as the moisture content in coal increases, flame temperature decreases because of heat loss driven from latent heat of vaporization and reduction of heating value. As the volatile matter content in the coal increases, the temperature in the region near the burner increases, while the temperature in rear region of boiler decreases. The solution to keep the temperature in the rear region of boiler is suggested that particle size is needed to be larger. As the particle size increases, the temperature in the rear region of boiler show tendency to increase, for combustion burning time of coal could be extended.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.6
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• pp.32-41
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• 1999

Natural gas is an attractive fuel in view of environment benefits due to its flow carbon-to-hydrogen ratio. However, its compositions and properties are varied depending upon production regional groups. Therefore, study on the combustion characteristics of natural gas engines with a variety of compositions has been demanded for the efficient application of gas engines. This study aims to investigate the effects of gas composition on engine combustion characteristics. It was found that , by controlling an engine with fixed fuel nozzle area, power and heat release were subject to Wobbe Index. And at fixed excess air ratios, power and heat release were subject to low heating value of unit mixture . In addition, in case of constant nozzle area, combustion duration was found to be inversely proportional to CP(Combustion Potential), and the condition of fixed excess air ratios showed no change in combustion duration, regardless of CP.

• 한국연소학회:학술대회논문집
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• 1999.10a
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• pp.81-91
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• 1999

Fuel characteristics of sewage sludge as required for the fluidized bed incinerators have been evaluated. Sewage sludge is basically a solid fuel with high percentage of moisture. Moisture content of the fuel directly affects the heating value of the fuel and the exhaust gas composition. When the sludge of transported into the incinerator, sludge cake is subject to the mixing, break-up and heat-up. Fluidization process would enhance these physical processes. The sludge fuel could then undergo the moisture evaporation and devolatilization process. Subsequent oxidation of volatiles as well as the remaining char would then follow. Sludge samples are characterized with high percentage of volatiles out of total combustibles. Quantitative understanding of above listed subprocesses would certainly help in the utilization of fluidized bed incinerators. A limited set of fuel characterization tests including calorimetric analysis, proximate analysis, elemental analysis and thermogravimetric analysis were conducted for the selected sludge samples. The measurement reasults of sludge samples were reported along with some published data. Limited experience in the actual incinerator plant is also presented.

• 한국연소학회:학술대회논문집
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• 1999.10a
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• pp.165-172
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• 1999

Landfill gas has merely half heating value compared with liquified natural gas but can be greatly utilized as a commercial fuel. The authors have examined emission characteristics as well as measured burning velocity of LFG mixed gas which contains plenty of $CO_{2}$. With the viewpoint of fuel utilization, flame stability could be one of important characteristics of LFG. In this study, the comparison experiments are conducted between $CH_{4}$ and LFG for searching the region of flame stabilization based upon the flame blowout at maximum fuel stream velocity. As a result, it is found that stabilization region of LFG is not improved with that of $CH_{4}$ in non-swirl/or weak swirl jet diffusion flame. However, it is also known that flame stability is hardly affected by inert gas in the strong swirl with considering widened flame stabilization region of LFG rather than LNG.

• KIEAE Journal
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• v.10 no.3
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• pp.17-26
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• 2010

This study aims at exploring the characteristics of the Usonian houses of Frank Lloyd Wright from an ecological viewpoint. After considering the definition and application of ecological architecture through literature review, 28 Usonian houses were selected and analyzed for the study. Also, nine Usonian houses, which clearly have ecological and historical importance, were visited and more thoroughly analyzed. The result shows that Usonian houses are ecological in terms of 1) the relationship among nature, landscape and house, 2) the orientation, natural light and natural ventilation, 3) the use of natural local materials including wood, stones and bricks, 4) the use of floor heating (the On-dol system inKorea), 5) the human scale, 6) the use of the board and batten unit (an early system of prefabrication), and 7) the openness and flexibility of floor plans.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.821-825
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• 2002

ZnO thick films by Sol-Gel processing were investigated electrics, optics and the sensing characteristics of CO gas. Using the znic acetate dihydrate and acetylaceton (AcAc) as a chelating agent, stable ZnO sol was synthesized. ZnO phase was crystallized through the heat-treatment at $70^{\circ}C$ for 4hrs and influenced the sensing characteristics of the electrics and CO gas by uniform particle distributions not related particle size. The samples on the alumina substrate by thick films were investigated the properties of electrics and the effect of sensing. The sensitivity was so excellent in the sample of the heat-treatment at $600^{\circ}C$ for 12hrs and good in the heat-treatment for 1hrs generally. Crystallization and volatilization of organic materials according to the change of heating treatment temperature of thick films were analyzed by TG-DTA, XRD and mirostructure of thick films were observed by SEM.

• Journal of the Korean Home Economics Association
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• v.27 no.3
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• pp.103-115
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• 1989

This study has been a study on changes seen in rural kitchens and factors affecting the modernization of agrarian kitchen space. The major findings were as follows: 1) The physical changes in kitchen design were carried out rapidly after 1977. This period coincided directly with the period in which kitchen improvement projects were fostered by the Sae Ma-Eul UNDONG 2) The study showed the macro factors contributing to changes in kitchen space to be government policy and industrialization. The study showed the micro factors influening kitchen space changes to be classified along socio-demographic lines and family lifestyle. 3) The factors affecting the degree of satisfaction with kitchens have been divided into socio-demographic and lifestyle characteristics. The level of education achieved by the husband was the most significant among socio-demographic characteristics. Most important among lifestyle characteristics were the cooking fuel used during the slack farm season, eating habits, heating fuel and eating space respectively. The results of this study have some implications in terms of government housing policy. Policymakers should be aware of suitable kitchen spaces to rural households in order to meet their housing needs and expectations.

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.118-123
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• 2000

This experimental study was conducted to figure out the characteristics of convective heat transfer in non boiling vertical downward flow with polymer additives. This experiment was studied in 26mm diameter, 800mm heating length and $1{\times}10^5W/m^2$ heat flux. The polymer concentration ranged from 0PPM to 500PPM with corresponding from Reynolds number $3.3{\times}10^4$ to $6.8{\times}10^4$ in non boiling vertical downward flow. Experimental results show that the characteristics of convective heat transfer was a strong function of polymer concentration and it has decreased with increasing the polymer concentration in non boiling vertical downward flow.