• Journal of the Korean Electrochemical Society
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• v.4 no.3
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• pp.104-108
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• 2001

Naphthalene derived mesophase pitch WP) was spun into short fibers by using melt-blown technology. The pitch fibers oxidative stabilization were carried out heating rates of $2^{\circ}C/min,\;5^{\circ}C/min\;and\; 10^{\circ}/min$. The heating rate was a key factor to maximate the capacity of the Li-ion secondary battery through controlling the morphology of the graphitized fiber. The diameters of the melt-blown fibers prepared were in the range of $4{\mu}m\~16{\mu}m$ with functions of air jet speed, air temperature and the temperature of the nozzle. The graphitized fibers of $10{\mu}m$ diameters showed various morphological structure with heating rate of the stabilization. Radial, radial-random and skin-core cross-sectional structure of the fibers were observed at the respective heating rate of $2^{\circ}C/min\;5^{\circ}C/min\;and\;10^{\circ}C/min$. Most crystalline structure of graphite was obtained from the fiber stabilized at heating rate of $10^{\circ}C/min$ exhibiting the best anode performance with 400 mAh/g of capacitance and $96.8\%$ of charge/discharge efficiency.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.64.1-64.1
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• 2010

In this study, the energy and economic analysis of KIER Zero Energy Solar House (KIER ZeSH) was carried out. KIER ZeSH was designed and constructed in the end of 2009 for the purpose of more than 70% energy self-sufficiency in total load as well as less than 20% of additional construction cost. The several building energy conservation technologies like as super insulation, high performance window, wast heat recovery system, etc and renewable energy system. The renewable heating and cooling system is a kind of solar thermal system combined with geo-source heat pump as a back-up device. The capacity of 3.15kW solar BIPV system was also installed on the roof. The measurement by monitering system of ZeSH was conducted for one year from November 2009 to October 2010. The energy self-sufficiency and economic analysis were conducted based on the this monitering result. As a result, the energy self sufficiency is about 83% which is higher than that of the target and the payback period is 11 years.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.5
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• pp.13-19
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• 2014

Urea-SCR system is the selective catalytic reduction to reduce nitrogen oxides ($NO_x$) emitted from diesel vehicles. The objective of this study is numerical analysis of 3-dimensional unsteady melting problems of frozen urea by using an electric heater. It can be applied to determine capacity of power with respect to time and the location of the urea suction pipe in urea storage tank. The study includes the change of liquid volume fraction, temperature profiles and a influence of natural convection by using the commercial software STAR-CCM+(v7.06). The accuracy of the numerical analysis is estimated by comparisons with experimental data. After validation, a numerical analysis for freezing urea is conducted with four different heating power. From the results, it was found that relation of velocity of phase interface and amount of melting urea by increasing heating power in a container. There is also a difference in trend between velocity of phase interface and amounts of melting urea because of effect of natural convection.

• Journal of Biosystems Engineering
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• v.27 no.3
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• pp.235-240
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• 2002

Performance of the heat pump with attaching an air heat exchanger was investigated in the heating condition when the air heat exchanger was worked in the ambient air temperature of -5 to 11$\^{C}$ and air flow rate of 542 to 747 ㎡/h. Performance tests for heating condition were conducted in an experimental room equipped with heat pump. The performance tests were performed in a ambient temperature of -4 ∼ 11$\^{C}$, and room temperature of 4∼22$\^{C}$ respectively. Measured data(temperature, capacity of heat transfer and consumption of electronic power) were analyzed to the efficiency of HEEVA(Heat Exchanger fur the Evaporator), overall heat transfer coefficient and COP of heat pump. The results of inlet temperature for evaporator increased that the temperature was 2 ∼6$\^{C}$, and inlet temperature for condenser decreased that the temperature was 3 ∼ 8$\^{C}$. The results of comparing efficiency of HEEVA for the ratio of heat exchange between hot air and cold air showed that efficiency were considered to 91% because of the ratio of 83∼98%. The results of comparing of COP for the heat pump increased that improvement COP was approximately 0.3∼7.5 than HEEVA had not been operated.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.8 no.2
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• pp.187-197
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• 1996

A computer program for thermal design analysis has been developed to predict the operating characteristics and performance of an absorption heat pump to recover $30{\sim}40^{\circ}C$ of waste hot water. The effects of heat transfer area of the system components, temperature and mass flow rate of heat transfer medium, and solution circulation rate on the system performance are investigated in detail. The results obtained indicate that the COP is increased with a decrease in the temperature of driving steam and with an increase in the temperature of waste hot water while the COP is little affected by the variation of a hot water temperature. It is also found that the heating output is increased with an increase in the temperature of waste hot water and driving steam as well as with a decrease in the temperature of hot water. The simulation results are also compared with the experimental results for a periodic operation of the system and obtained a satisfactory agreement.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.1
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• pp.40-47
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• 1993

Gelatinization properties of the air-dried sediment of cowpea were investigated. The water-binding capacity of cowpea flour was drastically increased over the temperature range of 52~55$^{\circ}C$. The percent transmittance of flour suspension was linearly increased at temperature between $65^{\circ}C$ to 75$^{\circ}C$. The gelatinization temperature determined by differential scanning calorimetry was 63.4~76.$0^{\circ}C$. Cowpea flour showed a single-stage of swelling and a low solubility pattern. The minimum moisture content required for the gelatinization was 37.0% . The amylograph peak viscosity was greatly influenced by concentration of the flour, but was not affected by heating temperatures (85~94$^{\circ}C$) at a given concentration. The 20 min height and cold viscosity at 3$0^{\circ}C$ at a fixed concentration was negatively correlated (p<0.05) with heating temperatures.

• 한국태양에너지학회:학술대회논문집
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• 2012.03a
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• pp.451-456
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• 2012

This study was carried out to evaluate thermal performance of the renewable hybrid heat supply system with solar thermal system and wood pellet boiler for Zero Carbon Green home of apartment houses. The hybrid heat supply system was set up at Korea Institute Energy Research in 2011. The system was comprised of the wood pellet boiler unit with heat capacity designed as 20,000 kacal/hr, a evacuated tubular solar collector 3.74 $m^2$ of aperture area at the $20^{\circ}$ install angle, a 0.3 $m^3$ hot water storage tank, a 0.15 $m^3$ hot water storage tank for space heating. Thermal performance tests for one-house of apartment house were carried out by hot water load and heating load in winter season through the hybrid heat supply system. As a result, hot water energy supplied by the hybrid heat supply system was 11kWh in a day. Solar thermal energy portion was 2.99kWh which is 27% of the total hot water energy supply. wood pellet boiler supply portion was 8.017kWh which is 73% of the total hot water energy supply.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.539-543
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• 2009

When the suction pressure of compressor decreases under its limit, the compression ratio is increased causing the malfunctions of compressor. As the method to decrease the compression ratio, hot gas bypass system is usually adopted in heat pump system. In the hot gas bypass system, the discharged gas from the compressor is bypassed into the compressor suction, which causes the increase of suction pressure and the decrease of compression ratio. In this study, the characteristics and performances of the hot gas bypass system in heat pump was investigated experimentally with a variation of the bypass flow rate ratio. With the increase of the bypass rate ratio, the compressor suction pressure was increased, even though the total capacity and COP was decreased. From the analysis of the experimental results, the optimum pressure control algorithm was suggested in this study.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.357-362
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• 2009

As a unutilized energy, treated sewage water locates widespread near urban areas. From the previous survey, the sewage water is reported to hold energy potential up to 36,000 Tcal/year, which was 2.1% of the total domestic energy consumption and 9.7% of the energy usage in the household and business sector in 2006. Temperature of the sewage water differs locally, but its range is observed in a range of $20{\sim}25^{\circ}C$ in summer and $8{\sim}13^{\circ}C$ in winter. Since the temperature range of the sewage water has a better seasonal distribution about $5{\sim}10^{\circ}C$ compared to ambient air, it is a promising heat sink for summer or heat source for winter. The sewage water is also a high quality heat source from its abundant quantity and uniform temperature. Considering the ambient temperature of Korea is very low in winter, a heat pump system using the sewage water can be an alternative to prevent problems of capacity deficiency and frost formation.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.1503-1506
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• 2009

Bubble jet loop heat pipe is a newly devised variation of heat pipe in which heat is effectively transported by the latent heat of evaporation and condensation as well as the heat capacity of circulating working fluid. The circulatory and oscillating motion of the working fluid becomes possible by the motion of bubble jet which is generated at a narrow circular gap. These bubbles are condensed at the condensing section. Bubble jet loop heat pipe makes it possible to carry heat long distances upward and horizontal directions. Because Its structure is a very simple and a low cost, it is available for the floor heating, vinyl house heating, the defrosting of heat pump system and home refrigerator.