• Proceedings of the KSME Conference
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• 2001.11a
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• pp.785-790
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• 2001

Linear motors can drive a linear motion without intermediate gears, screws or crank shafts. Linear motors can successfully replace ball lead screw in machine tools, because they have a high velocity, acceleration and good positioning accuracy. On the other hand, linear motors emit large amounts of heat and have low efficiency. In this paper, heat sources of a synchronous linear motor with high velocity and force are measured and analyzed. To improve the thermal stiffness of the linear motor, an insulation layer with low thermal conductivity is inserted between cooler and machine table. Some effects of the insulation layer are presented.

• Journal of Advanced Marine Engineering and Technology
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• v.11 no.1
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• pp.39-52
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• 1987

Recently, the design problem of heat insulation have been reappraised in the aspect of energy saving due to the rising trend of energy cost. For example, that design problem is increasingly requsted in the fields of accommodation air conditioning systems, hot water supply systems, cargo handling systems, district heating or cooling systems. The rational design of heat insulation of piping systems can not only improve the overall efficiency of energy transfer but also give energy saving. In this paper, the heat insulation problem of district heating systems is therefore modeled as the multi-stage decision processes, suitable for dynamic programming technique. And take the object function as the sum of heat insulation material cost involved construction cost and heat loss cost, and propose the design method to minimize the object function for overall piping systems by dynamic programing. Effectiveness of design method presented here is proved by a computer simulation.

• Journal of Magnetics
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• v.16 no.1
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• pp.31-35
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• 2011

A silica aerogel sheet with a very low thermal conductivity is used to suppress the temperature increase of the Cu coil in an induction cooker by reducing the heat flow from the heat source (cooking pot). It is found that the temperature of the Cu coil is reduced significantly by the insertion of an insulation sheet between the heat source and the Cu coil, demonstrating the effectiveness of the insulation sheet in the suppression of the heat flow between the cooking pot and the coil. Furthermore, the temperature of the cooking pot increases more rapidly with the use of the insulation sheet, allowing for an increased efficiency of the induction cooker.

• Journal of Power Electronics
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• v.14 no.2
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• pp.203-216
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• 2014

In the conventional dc-dc converter, a pair of additional diode and the adjacent passive component capacitor/inductor can be added to the circuit with an X-shape connection, which generates a family of new topologies. The novel circuits, also called diode-assisted dc-dc converter, enhance the voltage boost/buck capability and have a great potential for high step-up/step-down power conversions. This paper mainly investigates and compares conventional dc-dc converter and diode-assisted dc-dc converter in wide range power conversion from the aspects of silicon devices, passive components requirements, electro-magnetic interference (EMI) and efficiency. Then, a comprehensive comparison example of a high step-up power conversion system was carried out. The two kinds of boost dc-dc converters operate under the same operation conditions. Mathematical analysis and experiment results verify that diode-assisted dc-dc converters are very promising for simultaneous high efficiency and high step-up/step-down power conversion in distributed power supply systems.

• Journal of Power Electronics
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• v.17 no.1
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• pp.253-261
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• 2017

For a single-phase active power filter (APF), designing a more efficient algorithm to guarantee accurate and fast harmonics extraction with a lower computing cost is still a meaningful topic. The common idea still employs a IRPT-based Park transform, which was originally designed for 3-phase applications. Therefore, an additional virtual signal generation (VSG) link is necessary when it is used in the single-phase condition. This method, with virtual signal generation and transform, is obviously not the most efficient one. Regarding this problem, this paper proposes a novel harmonics extraction algorithm to further improve efficiency. The new algorithm is based on the principle of trigonometric orthogonal functions (TOF), and its mathematical principle and physical meaning are introduced in detail. Its implementation and superiority in terms of computation efficiency are analyzed by comparing it with conventional methods. Finally, its effectiveness is well validated through detailed simulations and laboratory experiments.

• Korean Institute of Interior Design Journal
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• v.14 no.3 s.50
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• pp.46-54
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• 2005

This study explored how the elementary schools provided proper interior environments to the students in terms of ecological aspects. 14 cases-7 in Busan and 7 in Osaka which were newly built or remodelled since 2000 were selected. These schools were analyzed based on the eco-school guideline suggested In the former study. The guideline categorizes into three parts: 1) energy efficiency related with lighting, ventilation, heating and insulation, 2) greening, 3) sustainability including recycling water system and use of environmentally friendly materials. The results showed that Korean schools require more systematic planning for natural lighting, ventilation, Insulation, greening and new water system while Japanese schools need use of environmentally friendly materials and consideration for natural lighting, insulation and interior greening. Especially, natural lighting and natural ventilation through roof window, atrium, wind tower and use of natural insulation and blind window system should be basically considered at the Initial planning. Also, this study reveals that ecological approach including greening and natural lighting with various architectural form should be applied in future elementary school design to make the school environment more agreeable and economical.

• Transactions on Electrical and Electronic Materials
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• v.3 no.3
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• pp.34-38
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• 2002

In this paper, efficiency estimation of toxicity fee fire resistance cable experiments was measured smoke density of toxicity free fire resistance polyolefin insulation material and electric field dependence of tree shape in low density polyethylene (LDPE). One of the most serious causes of failure in high-voltage cables, can be an electrical discharge across an internal gab or void in the insulating material. Treeing due to partial discharge is one of the main causes of breakdown in the insulating materials and reduction of the insulation life. Therefore the necessity for establishing a method to diagnose the aging of insulation materials and to predict the breakdown of insulation and research of the fire resistance character has become important. First, we have studied on electric field dependence of tree shape in LDPE about treeing phenomena occurring on the high electrical field. Second, the measurement method is the attenuation quantity of irradiation by smoke accumulating with in a closed chamber due to non-flaming heat decomposition and flaming combustion. A main cause of fire-growth and generating toxic gas when, it bums, should be dealt with great care in life. safety design. The fire gases were occurred carbon monoxide and decomposition than in polyolefin due to incomplete combustion of PVC, which has high content of carbon in chemical compound.

• Journal of the Korean Solar Energy Society
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• v.30 no.5
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• pp.32-37
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• 2010

In order to handle the crisis about energy-environment problem, it is necessary to develop the future-oriented and innovative energy technology in architecture area. So the development of new technology for energy saving and alternative energy use has been spurred in this area. Double skin window system, which is an active covering to respond to the exterior change of the environment, is the skill that can reduce the indoor cooling and heating load and the environmental architecture can be realized. This study works out U-value of windows using the window-simulation program with the development and study of the double skin. In addition, the effect of the double skin insulation on the efficiency rating has been analyzed, applying to the certification system of the building energy efficiency rating which has implemented.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.11a
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• pp.10-11
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• 2018

Internal Insulation system is applied to the most apartment building in Korea. However due to the importance of building energy enhanced the interest of the exernal insulation system. The extermal insulation system has better thermal performance because the thermal bridge through the structure are rarely formed. But the thermal bridge around the window decrease the thermal performance of the envelope system. Therefore the technology for reducing the thermal bridge around window improves energy efficiency of the building. In order to this it is necessary to minimize the thermal bridge around window of building. In this study it is aimed to minimize the thermal bridge around the window of building. It was confirmed that the use of thermal bridge barrier imporved the heat transfer rate by 64% or more and the condensation reduction phenomenon by 42% or more compared with the exist technology. These thermal bridge barrier will be used as the main technology to improve the energy efficiency of building.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.115-118
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• 2000

In case of developing new motor, many examinations was tested to decide a motor efficiency and reliability. To give reliability judgment, traction motor winding insulation was tested by electrical method after appling electrical, heat, mechanical, environmental stress. In this study, stator form-wound winding of traction motor in urban transit E.M.U was tested by accelerative thermal degradation test. Stator form-wound winding was tested on the accelerative degradation composed of heat, vibration, moisture, overvoltage and researched insulation resistance, dielectric loss, partial discharge for insulation degradation properties, evaluated withstand voltage. Degradation temperature was $230[^\circ{C}]$, $250[^\circ{C}]$, $270[^\circ{C}]$, for stator form-wound winding respectively. On the test results of accelerative thermal degradation, insulation properties were relied all temperature until 10 times and expected life was evaluated by the rule of reducing $10[^\circ{C}]$ life into halves. Expected life was 31.8 years. It is guaranteed insulation reliability because of exceeding 25 years life times as considering.