• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.420-422
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• 2003

Aging and failure of motor insulation depend on the stresses imposed on it. The insulation life time depends on the severity of the stresses. The electrical aging by transient surge is very important to traction motor in EMU(electric multiple unit). This paper Presents the insulation characteristics of stator coil by transient surge from inverter. There are several nondestructive tests available for checking the condition of motor insulation, the probable extent of aging,. and the rate of which aging is taking pace. So the insulation characteristics of stator coil were each analyzed by measurement of leakage current, dielectric loss($tan{\delta}$), capacitance, polarization index(PI) and partial discharge. The method of diagnosis is able to analyze the aging condition and Predict the life of the traction motor in EMU.

• Proceedings of the KSR Conference
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• 2003.10c
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• pp.623-627
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• 2003

Aging and failure of motor insulation depend on the stresses imposed on it. The insulation life time depends on the severity of the stresses. The electrical aging by transient surge is very important to traction motor in EMU(electric multiple unit). This paper presents the insulation characteristics of stator coil by transient surge from inverter. There are several nondestructive tests 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 leakage current, dielectric loss($tan{\delta}$), capacitance, polarization index(PI) and partial discharge. The method of diagnosis is able to analyze the aging condition and predict the life of the traction motor in EMU.

• Journal of Magnetics
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• v.20 no.2
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• pp.110-113
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• 2015

Two kinds of magnetic fluids with different volume fractions are symmetrically filled into the W0.9 photonic crystal waveguide structure. The 2D plane-wave expansion method is used to investigate the slow light properties numerically. The constant group index criterion is employed to evaluate the slow light performance. The wavelength bandwidth ${\Delta}{\lambda}$ centering at ${\lambda}_0=1550nm$ varies from 32.4 to 44.2 nm when the magnetic field factor ${\alpha}_{\parallel}$ changes from 0 to 1. And the corresponding normalized delay bandwidth product can be tuned from 0.221 to 0.258. For comparison and optimization, two infiltration cases are investigated and the more advantageous infiltration scheme is found.

• Journal of the Korean Society of Food Science and Nutrition
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• v.24 no.2
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• pp.234-241
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• 1995

Effect of microwave heating on the oxidative stability of the soybean oil, sesame oil, butter and margarine were investigated by mearsuring fatty acids amout and tocopherol losses. The index for chemical properteis, free fatty acid, peroxide value, anisidine value, carbonyl value, conjugated diene and triene levels were also mearsured in the oil samples for 5, 10, 15 and 20 min of heating in a microwave oven. No significant difference was observed on the fatty acids composition in the fats and oils before and after microwave heating. During microwave treatment, the oxidative degradation of the tocopherols in the samples became greater with increasing heating time. The amount of tocopherols in the soild fats, butter and margarine, dropped drastically after 5 min of heating and reduced to 95% of their original levels after 20min heating ${\gamma}$-tocopherol in butter showed the most unstable states and completely destroyed during microwave treatment for 20min. On the other hand, 80% of tocopherols in the liquid oils were still remained after 5min of heating except $\delta$-tocopherol in sesame oil.

• Proceedings of the KIEE Conference
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• summer
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• pp.1124-1126
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• 2004

The measurements were performed to assess the insulation deterioration condition of the stator winding of Dae-Cheong hydro-generator ${\sharp}2$ which had been in service after being constructed 1980. After repair of the stator winding insulation. we conducted insulation diagnostic tests which include resistance, polarization index(P. I). AC current, dissipation factor($Tan{\delta}$) and partial discharges ($Q_{max}$). The results of diagnostic tests were compared to the previous records. On the basis of these test results. this paper tried to present the importance of insulation repair for the generator stator winding.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.90-93
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• 1997

고주파 반응성 스퍼터링 방법을 사용하여 희토류가 첨가된 SiO$_2$ 박막을 제작하여 특성을 조사하여, 양질의 희토류 원소가 첨가된 SiO$_2$ 박막의 최적의 제작조건을 도출하고 Er-Al:SiO$_2$ 박막의 소자웅용 가능성에 대하여 조사하였다 열처리전의 Er의 농도는 EDS(Energy dispersing x-ray spectrometer)로 측정한 결과 0.77% 로 농도를 나타내었고 코아층 첨가된 Er은 균일하게 분포되었다 크레드층의 굴절률은 633nm의 파장에서 측정하였을때 1.458이였고 코아층의 굴절률은 동일 파장에서 1.757이였다. 굴절률 분포도 (Refractive Index Profile)는 계단형 굴절률 분포로 코아층/클래드 굴절률 차 $\Delta$n$_{ESI}$ = 0.1였다.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2118-2122
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• 2005

This test was performed to assess the corelation of insulation deterioration condition with breakdown voltage of the stator winding of 3.3kV class induction motors which have been in service for 10 years after being installed in 1993. The insulation diagnostic tests include resistance, polarization index(P.I), dissipation factor$({\Delta}tan{\delta})$, maximum partial discharges (Qmax) and AC breakdown test. we evaluated the corelation of insulation diagnostic test with AC breakdown test for stator wilding of high voltage induction motor.

• Proceedings of the KIEE Conference
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• 2004.05b
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• pp.39-41
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• 2004

The measurements were performed to assess the insulation deterioration condition of the stator winding of Dae-Cheong hydro-generator #2 which had been in service after being constructed 1980. After repair of the stator winding insulation, we conducted insulation diagnostic tests which include resistance, polarization index(P.I), AC current, dissipation factor($Tan\delta$) and partial discharges ($Q_{max}$). The results of diagnostic tests were compared to the previous records. On the basis of these test results, this paper tried to present the importance of insulation repair for the generator stator winding.

• Communications of the Korean Mathematical Society
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• v.9 no.4
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• pp.961-973
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• 1994

A stochastics process $X = {X(t) : t \in T}$, with an index set T, is said to be infinitely divisible (ID) if its finite dimensional distributions are all ID. An ID process X is said to be a stochastic integral process if $X = {X(t) : t \in T} =^D {\int f_td\Lambda : t \in T}$ where $f : T \times S \to R$ is a deterministic function and $\Lambda$ is an ID random measure on a $\delta$-ring S of subsets of an arbitrary non-empty set S with the property; there exists an increasing sequence ${S_n}$ of sets in S with $U_n S_n = S$. Here $=^D$ denotes equality in all finite dimensional distributions.

• Steel and Composite Structures
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• v.43 no.2
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• pp.185-200
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• 2022

A Closed-form solution for dynamic response of a functionally graded (FG) nonlocal nanobeam due to action of moving harmonic load is presented in this paper. Due to analyzing in small scale, a nonlocal elasticity theory is utilized. The governing equation and boundary conditions are derived based on the Euler-Bernoulli beam theory and Hamilton's principle. The material properties vary through the thickness direction. The harmonic moving load is modeled by Delta function and the FG nanobeam is simply supported. Using the Laplace transform the dynamic response is obtained. The effect of important parameters such as excitation frequency, the velocity of the moving load, the power index law of FG material and the nonlocal parameter is analyzed. To validate, the results were compared with previous literature, which showed an excellent agreement.