• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.331-336
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• 2004

Due to the outstanding insulating characteristics, Laminated Polypropylene paper (LPP) and Kraft paper have been used as ac power insulation for conventional cable. Recently, both of LPP and Kraft has been studied as main insulation fur high temperature superconducting (HTS) cable. Ifowever, studies on the use of LPP/Kraft paper for HTS cables are thinly scattered. In this paper, the comparison among LPP, Kraft and LPP/Kraft Samples impregnated with liquid nitrogen $(LN_2)$ on dielectric insulation characteristics was investigated. It was found from the experimental data that the breakdown strength becomes lower in the order LPP, Lpp/Kraft and Kraft but the lifetime indices n becomes lower in the order Kraft, LPP/Kraft, LPP. Moreover, partial discharge inception and dielectric loss tangent become lower in the order Kraft, LPP, LPP/Kraft.

• Journal of the Korea Institute of Building Construction
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• v.19 no.6
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• pp.539-547
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• 2019

Recently, the international community signed a climate change agreement to prevent global warming. Yet currently, the fossil fuels have been widely used in to supply building energy for cooling and heating. The Green Building certification (G-SEED), an energy efficiency rating for new or existing buildings requires that buildings meet certain conditions. Insulation is used as a building material to reduce the energy supply to buildings and to improve the thermal insulation, and it accounts for more than 90% of the total heat resistance provided by the building surface components that meet the energy-saving design standards of new buildings. In this investigation, a performance evaluation study was conducted through an experimental study by directly extracting the foam polystyrene insulation on-site during the remodeling of a building that was in the range of 22~38 years old. Through tests, it was found that the thermal conductivity of the extrusion method insulation (XPS) was reduced by 48% and the compressive strength of XPS decreased by 36% compared to KS M 3808, which is the initial quality standard. For bead method insulation (EPS) with a thickness of 50mm, the thermal conductivity, the compressive strength, and flexural failure load were similar to the initial quality standard. Therefore, in the calculation of the primary energy requirement per unit area per year, the performance of bead method insulation can be estimated simply by considering the thickness of the insulation, while a correction factor that considers its performance deterioration should be applied when extrusion method insulation is used.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.289-290
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• 2008

The purpose of this paper is to analyze AC Breakdown of solid/air composite insulation depending on the thickness and the pressure of dry air for eco-friendly insulation. SF6 gas has been widely used in electric equipment as gas insulation because of high dielectric strength and arc extinguishing performance. However, because SF6 gas is one of the green house effect gases, alternative insulation such as SF6 mixture, extremely low temperature gas, vacuum, liquid and solid insulating are being investigated.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.10a
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• pp.21-24
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• 2000

Traction motors driven by several type inverters have been subjected to increasing demands for higher operating temperature, more demands for duty cycles, higher starting current, frequent voltage transients and finally severe environmental exposure. For applications to inverter duty, traction motors needs a special insulation system, which has characteristics of increased bond strength, lower operating temperature and higher turn-to-tum insulation. Also it needs major contributors to insulation life and reliability of motors, which more considered by temperature, voltage, frequency, rise time, pulse configuration, wire thickness and insulation materials. In this paper, to evaluate of reliability and expected life, it is analyzed the several stresses and their degradation mechanism on insulation system of AC traction motor.

• 전기의세계
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• v.22 no.3
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• pp.13-24
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• 1973

In this report, as a method to solve the problems on impulse insulation coordination in ribbon core transformer owing to it's BIL stepping up, new design to alter winding distribution of multiple-layer concentric winding to Convex type winding is proposed. The main focus of this method is to settle the weakness of axial direction insulation strength and as a result of theoretical analysis through experiment of model transformers, the following conclusions are obtained; (a) As the electric loadings in a design which increases by strengthenning axial direction insulation endurance in presently avarilable transformers owing to it's BIL stepping up can be restricted in Convex type winding, reasonable design will be suited to the transformer with higher BIL. (b) Convex type winding is a very improved insulation design in respect of insulation coordination because it has shield plate effect to even impulse oscillation. (c) There is a disadvantage to cause leakage flux to increase in Convex type winding, however, the constancy of electric loadings in a design in spite of BIL stepping up restricts the increase of leakage flux to some extent.

• Proceedings of the KIEE Conference
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• 1998.07e
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• pp.1617-1619
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• 1998

In the nation, 154kV XLPE cable with an insulation thickness of 23mm have been used for transmission lines. The thickness is designed by old parameters which were determined by Kreuger, Oudin et al. in 1960s. By the way, the manufacturing technology has been developed. Especially in extruding and curing process we are using a triple common extruding head and applying gas-curing process. It allows the quality of XLPE cable improved. The paper evaluates the AC minimum insulation breakdown strength of XLPE power cable using model table. We can verify the uplifted insulation quality. And we expects the cable insulation thickness to be reduced applying the new parameter to the cable insulation design.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.1285-1287
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• 2003

The aging of the insulation reduces the electrical and mechanical strength of the insulation. At same point, a voltage surge or mechanical shock from a traction motor start will fracture or break down the insulation. To achieve the expected life usually requires extensive laboratory evaluation of the insulation systems and the use of accelerated aging tests. There are several nondestructive test available for checking. the condition of motor insulation, the probable extent of aging, and the rate of which aging is taking place. So the insulation characteristics of stator coil were each analyzed by measurement of dielectric loss($tan{\delta}$), capacitance and partial discharge. The method of diagnosis is able to analyze the aging condition and predict the life of the traction motor.

• Journal of the Korea Institute of Building Construction
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• v.17 no.5
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• pp.419-427
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• 2017

In order to examine the possibility of practical use of aluminate cement concrete at low-temperature environment with insulation method, an experimental studies on flowability, setting time, freezing temperature, size variation and compressive strength of the mortar at low-temperature were conducted. Compressive strength was increased in use of CSA, aluminate cement with gypsum. Workability and physical properties were improved by using aluminate cement and gypsum. In addition, freezing resistance and physical properties were improved by applying the insulation curing method. Especially, when alumina cement and gypsum were used together, the insulation curing method was more effective in improving the compressive strength.

• Journal of the Society of Naval Architects of Korea
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• v.56 no.6
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• pp.515-522
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• 2019

Since Liquefied Natural Gas (LNG) is normally carried at 1.1 bar pressure and at -163℃, special Cargo Containment System (CCS) are used. As LNG carrier is becoming larger, typical LNG insulation systems adopt a method to increase the thickness of insulation panel to reduce sloshing load and Boil-off Rate (BOR). However, this will decrease LNG cargo volume and increase insulation material costs. In this paper, silica aerogel, glass bubble were synthesized in polyurethane foam to increase volumetric efficiency by improving mechanical and thermal performance of insulation. In order to increase dispersibility of particles, ultrasonic dispersion was used. Dynamic impact test, quasi-static compression test at room temperature (20℃) and cryogenic temperature (-163℃) was evaluated. To evaluate the thermal performance, the thermal conductivity at room temperature (20℃) was measured. As a result, specimens without ultrasonic dispersion have a little effect on strength under the compressive load, although they show high mechanical performance under the impact load. In contrast, specimens with ultrasonic dispersion have significantly increased impact strength and compressive strength. Recently, as the density of Polyurethane foam (PUF) has been increasing, these results can be a method for improving the mechanical and thermal performance of insulation panel.

• KIEAE Journal
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• v.9 no.6
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• pp.13-18
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• 2009

Korean traditional houses have been developed in harmony with natural environment and comfortable indoor condition by using the natural resources including building layout, space composition and materials. Originally Korea traditional architectures have used wood lintel constructions and loess walls through the many years. Theses loess have many strength such as highly heat capacity, controling of humidity, a deodorant than any other materials. Nowaday it is recommended to use exterior and interior walls in loess wall to meet the eco-friendly materials to improve our residental environmental. Thus this study aims to research the sound insulation performance of traditional loess brick wall varied with thickness, thermal insulation materials and cavity wall. The sound insulation performance of these loess walls are compared with other masonry wall's and sound insulation performance of th walls were tested in anechoic laboratory to measure the sound transmission loss of these walls. The loess brick wall with 75mm thickness of cavity is shown the sound insulation performance with Rw 57 which is nearly same performances of 1B brick wall and cement 8' block wall, The improving effect of insulation materials is shown in the high frequency bandwidth. Especially, there is improving as much as 11 dB using the extruded poly stylene form(75mm) and poly ethylene film(0.7mm).