• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2274-2276
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• 1999

In this work, temperature rise and eddy current distribution on the enclosure and conductor of 3 pole gas insulated switchgear were investigated using analytical and experimental measures. The design of the diameters of the conductors and the enclosures of a meal clad gas insulated switchgear is primarily based on the insulation requirements. It is very difficult problem to predict the temperature rise of enclosed switchgear due to the complexity of the phenomena of heat transfer and existence of eddy current loss. To overcome this situations, we focused on the eddy current distribution on the enclosure of switchgear caused by high current 3 pole conductor as a fundamental basis. The experimental results about temperature distribution of 3 pole gas insulated switchgear were reported and measurements are compared with predictions of three-dimensional thermal model for eddy current analysis. As a result, three dimensional numerical analysis found to be in close relationship with experimental results and thermal model is efficient to predict the abnormal temperature rise in switchgear.

• Korean Journal of Materials Research
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• v.27 no.7
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• pp.353-358
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• 2017

Recycled cenosphere, which is a hollow shaped particle from fly ash, has become attractive as a building material due to its light weight and excellent heat insulation and soundproof properties. In this paper, we investigated the effect of cenosphere size on the physical and optical properties. High brightness of cenosphere as raw material is required for a wide range of ceramics applications, particularly in fields of building materials and industrial ceramic tiles. Cenospheres were sorted by particle size; the microstructure was analyzed according to the cenosphere size distribution. Cenospheres were generally composed of quartz, mullite, and amorphous phase. Colour measurement corresponding to chemical composition revealed that the contents of iron oxide and carbon in the cenospheres were the major factors determining the brightness of the cenospheres.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.8 no.2
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• pp.27-35
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• 2012

Five zero energy house models developed in Korea for the purpose of the energy performance were compared and analyzed in the study. The standard passive house model applying common technology and efficient energy performance elements was proposed. Standard passive house 5 models have been developed commonly aiming at 100% energy saving, applying high-performance and high-efficiency exterior thermal insulation, using 3 low-e coated window system, and targeting average 0.65 ACH to enhance privacy. Energy recovery ventilators and dry and cold radiant heating floor has been partially applied. Eco-design techniques such as the awning device, heat insulating door, using natural light have been used. Solar and geothermal systems as the application of renewable energy technologies have been commonly applied. And fuel cells were applied to a partial model. The standard model based on common technical elements and average performance of each element and obtained from five model analysis has been proposed in the study.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.231-234
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• 1998

In this experiment, A1$_2$O$_3$thick films were prepared by electrophoretic method using A1$_2$O$_3$ fine powder of which compositions were FA-5-500 and FA-5-900. As a result of measurement for A1$_2$O$_3$ thick film characteristics due to applied voltage, deposition time and additives condition, the result of deposited films exhibited superior than others when the applied voltage and deposition time were 65 volts and 2 seconds in case of using modified suspension medium added additives. When taken a heat treatment and sintered A1$_2$O$_3$ deposition film made by electrophoresis with A1$_2$O$_3$ suspension medium at 1$700^{\circ}C$ for 5 minutes in hydrogen environment, it could be fabricated in good uniformity and electric characteristics as the A1$_2$O$_3$ insulating thick films.

• Progress in Superconductivity and Cryogenics
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• v.16 no.1
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• pp.14-18
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• 2014

The mechanical, electrical and thermal characteristics of insulating materials may significantly affect the performance and reliability of electrical devices using superconductors. General method to provide insulating layer between coated conductors is wrapping coated conductor with Kapton tape. But uniform and compact wrapping without failure or delamination in whole coverage for long length conductor is not a simple task and need careful control. Coating of insulating layer directly on coated conductor is desirable for providing compact insulating layer rather than wrapping insulating layers around conductor. Ceramic added polymer has been widely used as an insulating material for electric machine because of its good electrical insulating properties as well as excellent heat resistance and fairy good mechanical properties. The insulating layer of coated conductor should have high breakdown voltage and possesses suitable mechanical strength and maintain adhesiveness at the cryogenic temperature where it is used and withstand stress from thermal cycling. The insulating and mechanical properties of polymer can be improved by adding functional filler. In this study, insulating layer has been made by adding ceramic particles such as $SiO_2$ to a polymer resin. The size, amount and morphology of added ceramic powder was controlled and their effect on dielectric property of the final composite was measured and discussed for optimum composite fabrication.

• Journal of the Korean Ceramic Society
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• v.48 no.5
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• pp.404-411
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• 2011

The humidity controlling ceramic materials was developed by applying the phenomena of dew condensation in the capillary. It is said that the humidity range which human feels comfortable is from 40 to 70% in relative humidity. In this study, the ceramic tile using natural soils such as diatomite for interior wall was investigated. In particular, we had introduced novel processing routes for fabricating microcellular ceramics tile using hollow microsphere as a pore former. The microcellular pores in the humidity controlling ceramic materials showed the superior properties such as light-weight, heat insulation. The cell density was ${\sim}1.0{\times}10^9$ cells/$cm^3$ and density of sample was 0.65 g/$cm^3$ in the case of 1.71 wt% hollow microsphere content. Also, it is observed that the BET surface area and the pore volume of the sintered diatomite tile have the values of 40.92 $m^2$/g and 0.173 $cm^3$/g.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.50 no.2
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• pp.65-72
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• 2001

This paper presents the design and test results of a 10kVA single phase HTS transformer which is operating at 77K. Double pancake windings with BSCCO -2223 HTS tape and GFRP cryostat with room temperature bore are used in the transformer. Four double pan cake windings were used in pancake windings are connected in parallel to conduct the secondary current of 45.4A. the rated voltages of each winding are 440/220V. Numerical calculation using Finite Element Method was used to evaluated the performance of each arrangement. Considering the magnetizing reactance, leakage reactance, electrical insulation and the circulating current in low voltage winding which had two windings in parallel, HLLH arrangement was finally chosen. Estimation of the AC loss, magnetizing loss and self field loss, in the design stage, where effects of perpendicular field and parallel field are considered. Room temperature bore type cryostat has been constructed and its heat loss was measured.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.05b
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• pp.57-60
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• 2004

Electrical arc is the final stage of insulation breakdown and has high current density which cause heat and light in insulator. Insulator under electrical arc lost its insulating strength and eternal damages. Conventional criterion of electrical arc resistance in Standards have depended on the change of sound pressure and light color after damages on insulator by electrical arc. The recognition of these changes is done by human himself which was very subjective and resulted in some error to judge whether insulator has damages or not. This paper has shown that antenna method is the appropriate measure to judge electrical arc resistance for insulator. Antenna measures the electromagnetic waves radiated from tungsten electrodes with 6mm gap regulated by KSC2130. Applied voltage cross two tungsten electrodes have two different methods such as 1/8 10 and continuous 10mA. Signal amplitudes obtained by antenna has diminished after the damage of insulator, which will provide objective and good way to judge the electrical arc resistance.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.05b
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• pp.138-141
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• 2004

In this paper, we Investigated effects on impurities and water of semiconductive shield through a thermal, mechanical, and absorption experiment to estimate performance of insulating materials in power cable. Specimens had been prepared 22[kV], 154[kV] XLPE power cables and then were made of sheet form with XLPE and semiconductive shield with dimension of 0.4[mm] ~1.2[mm] of thickness from power cable. Heat capacity $({\Delta}H)$ and glass trasition temperature (Tg) of XLPE sheet were measured by DSC (Differential Scanning Calorimetry). We could know that thermal stabilities of 154[kV] are more excellent than 22[kV] from this experimental result. The strain of mechanical properties in 22[kV] and 154[kV] XLPE was 486[%], 507[%] and stress was 1.74$[kgf/mm^2]$, 1.80$[kgf/mm^2]$. The absorption contents of existing semiconductive shield were measured 710[ppm] to 1,090[ppm], and semiconductive shield of 22[kV] cable was measured 14,750[ppm] to 24,780[ppm]. We thermal and mechanical properties of 154[kV] could know more excellent than 22[kV] from this experimental result.

• Korean Institute of Interior Design Journal
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• v.18 no.6
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• pp.28-35
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• 2009

The purpose of this study is to analyze the state-of-the-art housing cases with passive cooling technologies and to explore the feasibilities for their applications in domestic housing design. Nineteen Leadership in Energy and Environmental Design housing cases from 2002 to 2007 were selected and analyzed their used passive cooling technologies. Besides traditional passive cooling technologies such as site planning according to the sun direction, the use of thermal mass, insulation, shading, below-ground spaces and ventilation, the relatively new technology trends were detected as followings; the use of high performance envelope, operable windows, and geo-thermal energy as the cooling source of heat pumps, increased areas of photovoltaic cells, and the education of the owner and tenants about the adopted passive cooling technologies in a building. Especially, the education may have not been focused in the domestic design despite of its effectiveness on the appropriate operations of passive cooling technologies. The results of this study show their positive adaptations would be beneficial to domestic housing design to reduce energy costs and have cooler housing environments in summer.