• KIEAE Journal
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• v.14 no.6
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• pp.81-86
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• 2014

In recent years, many researchers have considered the building energy consumption reduction accordingly to deal with abnormal climate changes and greenhouse gas reduction. However, the lighting energy use ratio has increased in spite of the development of the high efficiency lighting device. Therefore, the study aims to produce the LED lighting applications for the effective lighting heat removal by using the heat characteristics of LED lighting and analyzing the heat removal effect. In order to increase radiant heat efficiency, the heat pipe and heat sink was attached on PCB as LED lighting applications. Experiment was conducted to verify the temperature and air velocity of inside duct: thermocouples, anemometer. The heat removal effect of LED lighting applications was measured by observing the temperature of the lighting applications and the change of air velocity in duct. The experiment shows that the temperature change in the duct according to air velocity was $0.9{\sim}5.8^{\circ}C$. It is also concluded that heat removal was calculated from 33 to 81W.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.2
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• pp.26-34
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• 2011

Hybrid powertrain systems have been developed to improve the fuel efficiency of internal combustion engines. In the case of a parallel hybrid powertrain system, an engine and a motor are directly coupled. Because of the hardware configuration of the parallel hybrid system, friction and the pumping losses of internal combustion engines always exists. Such losses are the primary factors that result in the deterioration of fuel efficiency in the parallel-type hybrid powertrain system. In particular, the engine operates as a power consumption device during the fuel-cut condition. In order to improve the fuel efficiency for the parallel-type hybrid system, cylinder deactivation (CDA) technology was developed. Cylinder deactivation technology can improve fuel efficiency by reducing pumping losses during the fuel-cut driving condition. In a CDA engine, there are two operating modes: a CDA mode and an SI mode according to the vehicle operating condition. However, during the mode change from CDA to SI, a serious fluctuation of the air-fuel ratio can occur without adequate control. In this study, an air-fuel ratio control algorithm during the mode transition from CDA to SI was proposed. The control algorithm was developed based on the mean value CDA engine model. Finally, the performance of the control algorithm was validated by various engine experiments.

• Journal of Fisheries and Marine Sciences Education
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• v.20 no.3
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• pp.500-507
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• 2008

Hot air drying is a method that let moistures evaporate by heat exchange between heating air and dry target. This way is dominating more than about 70% of dryers that the use extent is wide fairly, and is established in domestic than dryer that use conduction or radiation etc. Most of research about drying had been emphasized in size of device through analysis for these dry phenomenon plain, heating topology, and aspect of form and so on by dry target's special quality, and research about device development or waste heat withdrawal technology in energy utilization efficiency side is slight real condition. Therefore, in this study, Investigated numerically about thermal efficiency elevation that is leaned against as that change the temperature of inlet and outlet in heat exchanger of the hot air drying tower.

• Journal of the Korean housing association
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• v.15 no.3
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• pp.101-108
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• 2004

To find more efficient exhaust effect, air curtain of upward or downward trend in gas table and left or right side of range hood were made. As result that film vapor from range hood lower part by digital camera, the air current change by moving existence and nonexistence of exhaust fan and direction of air curtain were known. Under all experiment condition, upward air curtain superior exhaust performance.

• Plant Journal
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• v.7 no.2
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• pp.44-51
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• 2011

Given the fact that the entire bituminous coal used for a boiler is imported, the supply of coal is often affected by the rise of international coal price. Moreover, coal suppliers have been diversified due to the competition among power generation companies for reducing costs and inexpensive sub-bituminous coal is used. As a result, boilers combustion conditions have been deviated from the initial boiler design. This requires the selection of adequate excessive air ratio for different combustion conditions to enhance the efficiency of boiler operation. The boiler efficiency has been identified through an examination on the change of excessive air ratio by mixed fuel in unit 8 of Dangjin power plant complex. In addition, an excessive air ratio was calculated based on the examination result. According to the study result, the adequate excessive air ratio was 13% when Macquarie and Powder river were mixed at a ratio of 5:5 and when Sonoma and Megaprima persada were mixed at a ratio of 5:5. When BHP Billiton and Powder river were mixed at a ratio of 4:6 and Centennial and Batubara were mixed at a ratio of 3:7, the adequate excessive air ratio was 11%.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.762-767
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• 2009

Some types of semi-Volatile organic compounds (SVOC) that are emitted from plastics used in building materials and household appliances have associated health risks, even at low concentrations. In this study, micro chamber method for measuring SVOC is introduced and SVOC such as di (2-ethylhexyl) phthalate and butylated hydroxyltoluene emitted a flooring material were measured using a micro chamber method. Airflow characteristics in a micro test chamber deeply depended on air exchange rate. From the evaluation using an index of air change efficiency, such as the air age and the coefficient of air change performance, a fixed air exchange rate of $1.5\;h^{-1}$ in the micro chamber is desirable.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.4
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• pp.106-112
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• 2013

Compression ratio is an important factor affecting engine performance and emission characteristics since thermal efficiency of spark ignition engine can be theoretically improved by increasing compression ratio. In order to evaluate the effect of compression ratio change in HCNG engine, natural gas engine was employed using HCNG30 (CNG 70 vol%, hydrogen 30 vol%). Combustion and emission characteristics of CNG and HCNG fuel was analyzed with respect to the change of compression ratio at each operating condition. The results showed that thermal efficiency improved and $CH_4$, $CO_2$ emission decreased with the increase in compression ratio while $NO_x$ emissions were decreased at a certain excess air ratio condition. Higher thermal efficiency and further reduction of exhaust emissions can be achieved by the increase of compression ratio and the retard of spark timing.

• Journal of the Korean Solar Energy Society
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• v.34 no.3
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• pp.115-121
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• 2014

With increment on interesting about improving renewable energy efficiency, many research have been conducted and the research about hybrid air-water heater using solar energy that can make heating air and hot water has been conducted also. In this experiment, the temperature difference and thermal efficiency were investigated when two heating medium(air and liquid) was working simultaneously. As a result, thermal efficiency showed 44% to 88% when these heating medium was working simultaneously depending on operation condition and it is better than traditional solar collector. Also possibility of application into building equipment also was confirmed based on temperature and thermal efficiency. But necessity of additional studies about proper operation condition according to purpose of use and heat load was confirmed because change of thermal efficiency by air velocity and flux of liquid was shown a huge difference.

• Journal of Korean Society for Atmospheric Environment
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• v.28 no.6
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• pp.675-687
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• 2012

Applying an external electric field across air filter media is one of methods to improve the filtration performance. Metal wire meshes have been commonly used as electrodes situated on both sides of a thick filter pad. For a thin filter medium a short circuit, known as the biggest drawback for applying an external electric field to air filter, can occur at the closest point between electrodes. In this study several types of insulated meshes were prepared by coating #50 meshes with a dielectric material, Nylon 66, and the filtration property of air filter was evaluated at the presence of external electric field using those insulated meshes as electrodes and compared with that of filters using bared meshes. The collection efficiency of tested filter was increased from 78% to 95% for singly charged 100 nm particles by application of external electric field. As a result, there was no significant difference in collection efficiency between filters with insulated and bared electrodes. Similar results could be also seen from the tests using polydisperse particles. Finally, through this study, we found that the insulation of mesh electrodes doesn't affect the filtration performance of fibrous air filter under external electric field.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.1955-1961
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• 2008

A lot of researches on a linear induction motor(LIM) have been advanced to realize a traction system with high efficiency and performance for railway transit for a long time. However, most of them are limited in design of a LIM part such as Primary and Secondary. At a LIM which is traveling, the change of an air-gap(It occurs by a construction tolerance of a secondary reaction plate) becomes the cause which decreases a smoother ride and the efficiency of railway transit system. Therefore, uniform air-gap operation of LIM is important issue to improve the system efficiency. However, the researches which control the air-gap length of the LIM with technical and high-cost problem have been not advanced a lot. Therefore, in this research, it is introduced an air-gap control system for performance test machine of a scale-downed LIM which is able to control the air-gap length of the LIM and monitor a variety of performance changes of the propulsion system, and conducted a research on feasibility of the system based on characteristic analysis.