• KIEAE Journal
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• 제12권1호
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• pp.127-132
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• 2012

The energy consumption in the world is growing rapidly. And the environmental issues of climate become a important task. The interest in renewable energy like wind and solar is increasing now. Especially, by reducing power transmission loss, a small wind power is getting attention at the residential areas and campus of university. In this study, we attempted to estimate and compare the wind energy density using wind data of AWS (Automatic Weather Station) of H University. In this case of a campus, the weibull distribution parameter C is 2.27, and K is 0.88. According to the data, the energy density of the small wind power is 12.7 W/m2. We did CFD(Computational Fluid Dynamics) simulations at H University campus by 7 wind directions(ENE, ESE, SE, NW, WNW, W, WSW). In the results, we suggest 4 small wind powers. The small wind power generating system can produce 4,514kWh annually.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제48권6호
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• pp.330-335
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• 1999

This paper proposed the p-q-r coordinate system where the instantaneous active power p, and the two instantaneous reactive powers qq, qr were defined. The three power components are linearly independent, so the compensation for the two instantaneous reactive powers leads to control the two components of the current space vector. With the theory, the neutral current of a three-phase four-wire system can be eliminated by only compensating the instantaneous reactive power using no energy storge element.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2017년도 춘계학술대회 논문집
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• pp.103.1-103.1
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• 2017

Nanocrystalline HfN coatings were prepared by reactively sputtering Hf metal target with N2 gas using a magnetron sputtering system operated in DC and ICP (inductively coupled plasma) condition with various powers. The effects of ICP power, ranging from 0 to 200 W, on the coating microstructure, corrosion and mechanical properties were systematically investigated with FE-SEM, AFM, potentiostat and nanoindentation. The results show that ICP power has a significant influence on coating microstructure and mechanical properties of HfN coatings. With the increasing of ICP power, coating microstructure evolves from the columnar structure of DC process to a highly dense one. Average grain size and nano hardness of HfN coatings were also investigated with increasing ICP powers.

• Communications for Statistical Applications and Methods
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• 제8권1호
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• pp.137-145
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• 2001

There are many situations in which the well-known tests such as log-rank test and Gehan-Wilcoxon test fail to detect the survival differences. Assuming large samples, these tests are developed asymptotically normal properties. Thus, they shall be called asymptotic tests in this paper, Several asymptotic tests sensitive to some specific types of survival differences have been recently proposed. This paper compares by simulations the test levels and the powers of the conventional asymptotic tests and their random permutation versions. Simulation studies show that the random permutation tests possess competitive powers compared to the corresponding asymptotic tests, keeping exact test levels even in the small sample case. It also provides the guidelines for choosing the valid and most powerful test under the given situation.

• 품질경영학회지
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• 제18권1호
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• pp.29-39
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• 1990

In this paper we propose a nonparametric test for testing the equality of several regression lines against ordered alternatives, when the independent variables are positive and all regression lines have a common intercept. The proposed test is based on a Jonckheere-type statistic applied to residuals. Under some conditions our proposed test statistic is asymptotically distribution-free. The small-sample powers of our test are compared with other tests by a Monte Carlo study. The simulation results show that the proposed test has significantly higher empirical powers than the other tests considered in this paper.

• 응용통계연구
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• 제4권1호
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• pp.33-45
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• 1991

변화시점 모형은 지금까지 한 시점에서 단 한 개의 관측자료를 갖는 모형만 생각해 왔다. 이러한 모형을 확장시켜 각 시점에 한 개 이상의 관측자료를 갖는 변화시점 모형을 생각한다. 이러한 모형에서 비모수적인 단측 그리고 양측 검정법을 찾았다. 검정 통계량은 지금까지 소개된 검정 통계량 형태를 확장시킨 형태이고 이들의 귀무가설 분포를 구하여 보았다. 또한 Monte Carlo연구를 통해 이들의 검정력을 비교해 보았다.

• 시큐리티연구
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• 제3호
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• pp.251-272
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• 2000

Attempts have also been made to locate security in the so-called 'policingdivision of labour' In order to understand this, it is necessary to identify some of the links which exist between public police organizations and the private security sector. Such links can be divided into six types : 1) Interpersonal links, 2) Joint operations, 3) Exchange of services, 4) Granting of special powers, 5) Public bodies hiring private personnel, 6) New organizational. Van Reenen provides a useful outline of the different dimensions of future Glibalization of policing. Developments, he suggests, are likely to proceed in four directions : 1) Co-operation : at this level, the nature and powers of national police systems are not required to change, co-operation occurring between self-standing forces. 2) Horizontal integration : this arises when officers obtain authority to operate in another country, or where government officials from one country get authority over the police in another country. 3) Vertical integration : this exists when a police organization is created which can operate within the area of the EC as a whole. 4) Competition : the internationalization of policing in Europe presents itself, more and more, as a market in which different policing systems trade their products.

• Journal of Communications and Networks
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• 제4권2호
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• pp.102-107
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• 2002

The theoretical performance of MMSE linear microdiversity combining in Rayleigh fading, additive interference channels has already been derived exactly in the literature. In the macrodiversity case the fundamental difference is that any given source may well have different average received powers at the different antennas. This makes an exact analysis more difficult and hence for the macrodiversity case we derive a bound on the mean BER and a semi-analytic upper bound on outage probabilities. Hence we provide bounds on the performance of MMSE linear microdiversity combining in Rayleigh fading with additive noise and any number of interferers with arbitrary powers.

• 한국응용과학기술학회지
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• 제9권1호
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• pp.1-6
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• 1992

New five N-acyl-N-methyl taurate and their sodium salts were synthesized by acylating sodium N-methyl taurate in water in the presense of inorganic alkali as a catalyst. Wherein acyl group is a straight-chain radical of 10 to 18 carbon atoms. These compounds were identified by infrared spectroscopy. Surface activities of these sodium N-acyl-N-methyl taurate including surface tension, Ross-Miles foaming powers, foam stabilities, emulsifying powers and detergency were measured respectively. Also critical micelle concentration(cmc) were evaluated. Consequently these anionic surfactants with long chain acyl amine showed good emulsifying power of O/W type and had a good detergence.

• 복식문화연구
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• 제21권5호
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• pp.780-791
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• 2013

This paper is concerned with the development of the silk trade and in particular with silk-ikat production. Early origins are explained and issues relating to the development of long-distance trade are discussed. The principal trading participants are identified and the focus is turned to silk-ikat production in Central Asia. It is recognised that the vast bulk of trade, along what became known as the 'Silk Route' (or 'Silk Road'), did not involve straight-forward or direct exchange between powers to the far east of the route and powers to the far west, but rather was done in stages between adjacent or not too distant locations. Diffusion of ideas was not therefore immediate and operational at one eastern or western extreme of a trading network but, rather, was a gradual process influencing adjacent participants, at stages between the geographic extremes over a long period of time.