• 전기의세계
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• 제29권9호
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• pp.577-583
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• 1980

This paper is intended to analyze the characteristics of breakdown of polyethylene dielectrics, which was caused by A.C. voltage after impulse fatigue, by using weibull distribution. The impact of impulse fatigue upon the accurance and development of tree and the impact of void upon treeing are investigated. From the results of experiment, it is found that the life of polyethylene subjected to impulse voltage is shorter than that not subjected to impulse voltage. And in the case of void existence, it's life comes to be short remarkably, and the breakdown is almost concentrated on its initiation. From the results observed by the microscope, it is found that the treeing phenomena varies according as whether impulse voltage was applied to polyethylene before being applied to A.C. voltage and whether polyethylene has void or not.

• Transactions on Electrical and Electronic Materials
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• 제15권6호
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• pp.348-352
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• 2014

In light of the sure protection function, the most important factors of a varistor are the clamping voltage ratio and degradation characteristics. The degradation characteristics of Pr/Co/Cr/Er co-doped zinc oxide varistors were investigated by impulse currents (0.4~2.1 kA) stress for the specified content of $Er_2O_3$ (0.5 and 2.0 mol%). The varistor doped with 2.0 mol% $Er_2O_3$ exhibited the best clamp characteristics, with the clamp voltage ratio (K) in the range of K = 1.63~1.88 at the impulse currents of 5-50 A. However, the varistor doped with 0.5 mol% exhibited excellent electrical stability, with variation rates for the breakdown field, for the nonlinear coefficient, and for the leakage current density of -6.9%, -12.6%, and -14.3%, respectively, after application of an impulse current of 2.1 kA. In contrast, the varistor doped with 2.0 mol% was destroyed after application of an impulse current of 1.2 kA.

• 응용통계연구
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• 제25권2호
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• pp.239-249
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• 2012

We estimate nonlinear impulse responses of stock indices by asset class by the Local Projection method as suggested by Jorda (2005) to compute impulse responses. The method estimates impulse responses without the specification and estimation of the underlying multivariate dynamic system unlike the usual way of vector autoregression(VAR). It estimates Local Projections at each period of interest rather than extrapolating into increasingly distant horizons with the advantages of easy estimation and non-linear flexible specification. The Local Projection method adequately captures the nonlinearity and asymmetry of the impulse responses of the stock indices compared to those from VARs.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2000년도 추계종합학술대회
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• pp.581-584
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• 2000

This paper describes the effect of lightning impulse current on ZnO varistors(390 V, 6.5 kA) used in low-voltage AC mains as a protective device against transient overvoltages. A lightning impulse current standardized in IEC 61000-4-5 is applied to the varistors, and the energy applied to the varistor at each time is about 12 J. In the experiment, various Parameters such as leakage current, reference voltage are measured with the number of applied impulse current. Also, micro-structure changes of the varistors after applying the lightning impulse current of 200 times are compared. The electrical characteristics of the varistors are degraded by overtime impulse current, showing increase in leakage current and decrease in reference voltage.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부 C
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• pp.907-909
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• 1998

This paper describes the effect of impulse current on degradation of ZnO blocks. In this study, an impulse current generator which can produce 8/20 [${\mu}s$], 3 [kA] and 4/10 [${\mu}s$], 5 [kA] waveform is designed and fabricated to simulate the lightning impulse current. The residual voltage, reference voltage, and leakage current flowing to the ZnO blocks are observed. The experimental results show that the leakage current increases continuously with the number of applied impulse current, but no significant changes in residual voltage and in operating voltage are observed until the ZnO block is destroyed. Also, it is confirmed that the main factor on degradation of ZnO blocks is rather the total energy applied to ZnO blocks than the peak value of the impulse current.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2003년도 추계학술대회 논문집
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• pp.95-98
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• 2003

When a shock wave discharges from an open end of a duct, an impulse wave is generated outside the duct, causing serious noise and vibration problems. The magnitude of the impulse wave can be reduced by installing of a perforated duct. In the current study, the characteristics of the impulse wave discharged from the exit of a perforated duct are numerically investigated. A TVD (total variation diminishing) scheme is used to solve the unsteady, axisymmetric, compressible Euler equations. In computations, the porosity of a perforated pipe $(\sigma)$ and the Mach number of incident shock wave $(M_s)$ are varied in the range of $\sigma=0\~19\%\;and\;M_s=1.01\~1.50$, respectively. The results show that the directivity and magnitude of impulse wave strongly depend upon the Mach number of incident shock wave and the porosity of the perforated pipe. The present CFD results are in close agreement with experimental results.

• 한국음향학회지
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• 제19권8호
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• pp.26-34
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• 2000

This paper presents a new adaptive impulse noise cancelling technique based on the adaptive nonlinear suppressing function. The proposed "adaptive threshold algorithm (ATA)" is controlled by the normalized power prior input data term, and this adaptive threshold makes the cancelling system highly robust against additive impulse noise. For the performance evaluation, we have tested the proposed algorithm with the observed signals simulated in various impulsive noise environments and real EMG signals. As a result the proposed algorithm shows superior performance of 51.7% to the available techniques in the points of SNR and MSE.

• 패션비즈니스
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• 제10권4호
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• pp.140-150
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• 2006

The purpose of this study was to examine affecting the addictive buying behavior toward fashion luxury products. 227 female college students were who purchased fashion luxury products surveyed for this study. For data analysis, descriptive statistics, factor analysis, and multiple regression were used. As the results, addictive buying toward luxury products was classified into three factors: impulse addictive, money addictive, and psychological addictive. Also, consumers' individuality pursuit was classified into four factors: unique choice, non-similarity choice, individual choice and non-social interest. Multiple regression results revealed that impulse buying, stress, and unique choice accounted for 38% of the explained variance in addictive buying toward luxury products. Also, regression results indicated that impulse buying, stress, unique choice and reference group accounted for 38% of the explained variance in impulse addictive buying. Finally, regression results pointed out that unique choice and impulse accounted 24% of the explained variance in psychological addictive buying. Based on these results, fashion social responsibility marketing strategies would be suggested.

• 한국생활과학회지
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• 제24권6호
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• pp.829-846
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• 2015

The purpose of this study was to examine the influence of materialism and clothing shopping orientation on clothing impulse buying. The subjects were 309 female college students in Gyeongsang provinces. The obtained data were analyzed by reliability analysis, frequency, factor analysis, correlation analysis and regression analysis. The major results of this study were as follows: First, two factors of materialism were identified: happiness pursuit materialism and possession pursuit materialism. Second, two factors of clothing shopping orientation were identified: conspicuous shopping orientation and hedonic shopping orientation. Third, a significant positive correlation was found among two factors of materialism, two factors of clothing shopping orientation, and clothing impulse buying. Fourth, possession pursuit materialism influences clothing impulse buying through conspicuous shopping orientation. Fifth, happiness pursuit materialism influences clothing impulse buying through hedonic shopping orientation.

• Journal of applied mathematics & informatics
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• 제18권1_2호
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• pp.145-158
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• 2005

We formulate a stochastic control problem on proportional reinsurance that includes impulse and regular control strategies. For the first time we combine impulse control with regular control, and derive the expected total discount pay-out (return function) from present to bankruptcy. By relying on both stochastic calculus and the classical theory of impulse and regular controls, we state a set of sufficient conditions for its solution in terms of optimal return function. Moreover, we also derive its explicit form and corresponding impulse and regular control strategies.