• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.5
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• pp.176-180
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• 2013

After-treatment apparatus ceramic DPF (diesel particulate filter) have been applied to reduce harmful particulate matters(PM) among emissions from diesel engines so far, but they are easy to be fragile and weak in thermal shock. This research aims to investigate a metal type filter which is superior in mechanical strength and heat conduction rate and is beneficial economically in manufacturing. Basic performance of metal DPF such asloading test, temperature gradient test, thermal shock test, heat resistant test and back pressure was carried out. And then their experimental data provided key informations in designing and manufacturing such as detailed structures of metal mesh filter. Also diesel engine and vehicle of 2957cc displacement was tested under lug-down 3 mode and CVS-75 mode. PM reduction efficiency was 54.5% using metal DPF without loss of performance and fuel consumption.

• Bulletin of the Korean Chemical Society
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• v.19 no.3
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• pp.295-299
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• 1998

HSP104 protein in Saccharomyces cerevisiae is known to provide thermotolerance when induced by various kinds of stresses, such as a mild heat shock, ethanol, and hypoxia. It helps cells survive at an otherwise lethal temperature. Mechanisms by which HSP104 protein works are yet to be elucidated. In order to understand a molecular basis of thermotolerance due to HSP104 protein induced by a mild heat shock, studies on respiratory pathways were carried out in the wild type as well as in the hsp104 deleted mutant. Especially the degree of 13C-acetate incorporation into glutamate-C4 was examined for both strains using 13C-13C homonuclear spin coupling measurements, since glutamate is in a rapid equilibrium with α-ketoglutarate in the TCA cycle. In addition, the temperature effects on the rate of 13C incorporation are compared with or without HSP104 protein expressed. Finally, the inhibitory effect of HSP104 on the respiration pathway was confirmed by the measurements of oxygen consumption rates for both strains.

• Fire Science and Engineering
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• v.32 no.3
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• pp.35-41
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• 2018

Experiments were performed on 140 ml hexane pool fire extinguishment using a twin-fluid nozzle. For this pool fire, the area of the fire source (round shape of 80 mm in diameter) was $0.005027m^2$ and the measured heat release rate was 2.81 kW. The flow rates of water and gas (air and nitrogen) supplied to the twin-fluid nozzle were 156-483 g/min (~0.156-0.483 l/min) and 30-70 l/min, respectively. In the present experimental ranges, the high gas flow rate conditions led to the successful extinguishing of the pool fire. Under the low gas flow rate conditions in the extinguishment regime, the extinguishment time was long and the estimated water consumption was high. Under high gas flow rate conditions, however, the water flow rate conditions did not appear to have a great impact on the extinguishment time and estimated water consumption. On the other hand, in the present experimental ranges, the types of supply gas did not appear to affect the extinguishable flow rate condition, extinguishment time, and estimated water consumption. Finally, using the present experimental results with previous ones using a single-fluid nozzle, the water consumption of twin-fluid and single-fluid nozzles for extinguishing a 140 ml hexane pool fire were preliminarily compared and discussed.

• Journal of Power System Engineering
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• v.9 no.1
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• pp.82-88
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• 2005

This paper presents numerical study on dynamic characteristics of evaporator to control evaporator superheat and compressor capacity with optimum condition in refrigeration system. It is very important to reduce energy consumption and to keep room temperature within a very restricted range with minimum oscillation in some special applications of the refrigeration system. Heat exchange is mainly happened in the evaporator. So, making mathematical model of evaporator and analyzing evaporator characteristics are necessary in order to control the superheat and the capacity of the system. A mathematical model based on the one dimensional partial differential equations representing mass and energy conservation and a tube-wall energy is described. A set of ordinary differential equation is formulated by integrating separately over the two regions(two-phase and vapor) generally presented in a heat exchanger.

• Journal of Energy Engineering
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• v.23 no.4
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• pp.240-246
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• 2014

The present study has been carried out to reduce the heat loss from a refrigerator by changing thermal conductivity and partial removal of rubber magnet near refirgerator gasket. To perform this purpose, two dimensional heat transfer analysis for the horizontal cross sectional plane of a refrigerator has been accomplished. From the present study, it could be seen that the heat loss could be reduced nearly 7% by changing thermal conductivity of rubber magnet from 10W/mK to 1W/mK. The heat loss reduction, 17%, could be achieved by removal of rubber magnet near hotline and the effect on the heat loss reduction by partial removal of rubber magnet might be helpful for the refrigerator power consumption.

• KEPCO Journal on Electric Power and Energy
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• v.5 no.3
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• pp.173-179
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• 2019

Cryogenic air separation unit produces various gases such as $N_2$, $O_2$, and Ar by liquefying air. The process also varies with diverse production conditions. The one for SNG production among them has lower efficiency compared to other air separation unit because it requires ultrapure $O_2$ with purity not lower than 99.5%. Among factors that reduce the efficiency of air separation unit, power consumption due to compress air and heat duty of double column were representatives. In this study, simulation of the air separation unit for SNG production was carry out by using ASEPN PLUS. In the results of the simulation, 18.21 kg/s of at least 99.5% pure $O_2$ was produced and 33.26 MW of power was consumed. To improve the energy efficiency of air separation unit for SNG production, the sensitivity analysis for power consumption, purities and flow rate of $N_2$, $O_2$ production in the air separation unit was performed by change of air boosting ratios. The simulated model has three types of air with different pressure levels and two air boosting ratio. The air boosting ratio means flow rate ratio of air by recompressing in the process. As increasing the first air boosting ratio, $N_2$ flow rate which has purity of 99.9 mol% over increase and $O_2$ flow rate and purity decrease. As increasing the second air boosting ratio, $N_2$ flow rate which has purity of 99.9 mol% over decreases and $O_2$ flow rate increases but the purity of $O_2$ decreases. In addition, power consumption of compressing to increase in the two cases but results of heat duty in double column were different. The heat duty in double column decreases as increasing the first air boosting ratio but increases as increasing the second air boosting ratio. According to the results of the sensitivity analysis, the optimum air boosting ratios were 0.48 and 0.50 respectively and after adjusting the air boosting ratios, power consumption decreased by approximately 7% from $0.51kWh/O_2kg$ to $0.47kWh/O_2kg$.

• Journal of the Architectural Institute of Korea Planning & Design
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• v.34 no.2
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• pp.3-11
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• 2018

Korea has achieved a rapid economic development and with the increase in population and national income and the expansion of social and economic activities, energy consumption has rapidly increased too. Energy consumption per head has constantly increased and currently, power consumption per head is 7.5 times bigger than in 1985. Buildings occupy 25% of total energy consumption and especially, 50% of total energy is consumed for heating and cooling. In this situation, multi-family housing, which has constantly been increased, has an energy saving rate of 1.9%, which is the lowest level and this makes the government's energy policy for sustainable energy system development useless. Besides, energy consumption leads to secondary problems, such as air, water and marine pollution and heat pollution and wastewater/drainage and the increased use of fossil fuel is a fundamental reason for ozone layer destruction and global warming. Therefore, efficient energy consumption plans are required. This study aims to analyze energy performance in each block type of high-rise and diversified multi-family housing that accounts for 60% of all the housing forms, depending on the variations in stories through BIM-based energy simulation. For this study, four representative block types were selected, based on the multi-family floor plan, which is certified for energy performance evaluation and they were applied to the floor plan of a multi-family house that is scheduled to be built. Then BIM modeling was conducted from the fifth story to the 40th story at an intervals of 5 stories and based on the finding, energy characteristics of each block type and energy performance depending on the variations in stories were analyzed. It is considered that this would serve as objective data for block type and block story decision of energy performance-based multi-family housing.

• Journal of ILASS-Korea
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• v.15 no.3
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• pp.131-139
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• 2010

Gas motion within the engine cylinder is one of the major factors controlling the fuel-air mixing and combustion processes in diesel engines. In this paper, a special swirl-chamber is designed and applied to a DI (direct injection) diesel engine to generate a strong swirl motion thus enhancing gas motion. Compression, combustion and expansion strokes of this DI diesel engine with the swirl-chamber have been simulated by CFD software. The simulation model was first validated through comparisons with experimental data and then applied to do the simulation of the spray and combustion process. The velocity and temperature field inside the cylinder showed the influences of the strong swirl motion to spray and combustion process in detail. Cylinder pressure, average temperature, heat release rate, total amount of heat release, indicated thermal efficiency, indicated fuel consumption rate and emissions of this DI diesel engine with swirl-chamber have been compared with that of the DI diesel engine with $\omega$-chamber. The conclusions show that the engine with swirlchamber has the characteristics of fast mixture formulation and quick diffusive combustion; its soot emission is 3 times less than that of a $\omega$-chamber engine; its NO emission is 3 times more than that of $\omega$-chamber engine. The results show that the DI diesel engine with the swirl-chamber has the potential to reduce emissions.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.5
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• pp.277-282
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• 2015

During hot and humid weather, air-conditioners consume a large amount of electricity due to the large amount of latent heat. Simultaneous usage of a dehumidifier may reduce latent heat and reduce electricity consumption. In this study, dehumidification performance was measured for a small-sized dehumidification rotor made of inorganic fiber impregnated with metallic silicate within a constant temperature and humidity chamber. Regeneration to dehumidification depends on ratio, rotor speed, room temperature, regeneration temperature, room relative humidity and frontal velocity to the rotor. Results demonstrate an optimum area ratio (1/2), rotor speed (1.0 rpm), and regeneration temperature ($100^{\circ}C$) to achieve a dehumidification rate of 0.0581 kg/s. As the area ratio increases, the optimum rotation speed and the optimum regeneration temperature also increase. Above the optimum rotor speed, incomplete regeneration reduces dehumidification. Above the optimum regeneration temperature, increased temperature variation between regeneration and dehumidification reduces dehumidification. Dehumidification rate also increases with an increase of relative humidity, dehumidification temperature and flow velocity into the rotor.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.517-522
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• 2008

Ventilation rate and filter were selected to simultaneously satisfy indoor air quality and minimize energy consumption in residential housing. The concentrations of indoor particles were calculated using an adapted mass balance model for various ventilation airflow rates. To satisfy the guidelines for indoor concentrations of particles, the minimum ventilation rates of 1.0/h, 0.6/h and 0.4/h were required for MERV11, MERV13 and MERV14, respectively. And the fan power consumptions induced by ducts, a heat exchanger and a filter were calculated for various ventilation airflow rates. The increase in the ventilation rate caused a dramatic increase in the power consumption, but the filter performance did not have much of an effect on the fan power for ventilation airflow rates lower than 0.4/h. The use of the ventilation filter of MERV 14 was suggested at a ventilation rate of 0.4/h when the fan power consumptions were considered in addition to the indoor concentrations of particles and $CO_2$. The use of the MERV14 filter at a ventilation rate of 0.6/h could be more effective than the additional use of an indoor air cleaner when the residential housing unit was ventilated.