• Journal of Power Electronics
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• 제12권4호
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• pp.615-622
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• 2012

The switching frequency of the power electronic devices used in large synchronous motor drives is usually kept low (less than 1 kHz) to reduce the switching losses and to improve the converter power capability. However, this results in a couple of problems, e.g. an increase in the harmonic components of the stator current, and an undesired cross-coupling between the magnetization current component ($i_m$) and the torque component ($i_t$). In this paper, a novel complex matrix model of electrically excited synchronous motors (EESM) was established with a new control scheme for coping with the low switching frequency issues. First, a hybrid observer was proposed to identify the instantaneous fundamental component of the stator current, which results in an obvious reduction of both the total harmonic distortion (THD) and the low order harmonics. Then, a novel complex current controller was designed to realize the decoupling between $i_m$ and $i_t$. Simulation and experimental results verify the effectiveness of this novel control system for EESM drives.

• 생명과학회지
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• 제14권1호
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• pp.57-60
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• 2004

육종재료를 얻기 위하여 부산ㆍ경남지역에서 수집된 우리나라 재래종 옥수수 49계통에 대하여 주성분분두법을 이용하여 계통간 거리를 구하였고, 이를 이용하여 계통분류를 실시하였던 바 다음과 같은 결과를 얻었다. 계통간 거리에 의해 49계통은 4개의 계통군으로 분류되었고, 계통군 I 에는 11계통, 계통군 II에는 20계통, 계통군 III에 는 14계통, 그리고 계통군 IV에는 4계통이 속하였다. 계통군 I은 조생, 단간, 소수, 소분얼형의 계통들이었고, 계통군 II는 조생, 장간, 대수, 다수, 소분얼형의 계통이었고, 계통군 III은 만생, 단간, 소수, 다분얼형 의 계통이었고, 계통군 IV는 중생, 장간, 대수, 다수, 다분얼형의 계통들이었다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(1)
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• pp.313-316
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• 2003

Investigated about topology of each component of transformer and material choice method and property in this paper. Component of transformer is bobin, winding, insulating paper, Varnish etc. And, experiment and investigated special quality by primary winding of transformer and composition of secondary winding. Investigated loss of transformer and EMI decrease method. Investigated method to select winding size that consider frequency.

• Journal of the Korean Data and Information Science Society
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• 제6권2호
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• pp.77-83
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• 1995

The inferences on a series system under the usual condition using data from constant stress partially accelerated life tests and type I censoring is studied. Two optimal designs to determine the sample proportion allocated each stress level model are also presented, which minimize the sum of the generalized asymptotic variances of maximum likelihood estimators of the failure rate and the acceleration factors and the sum of the asymptotic variances of maximum likelihood estimators of the acceleration factors for each component. Each component of a system is assumed to follow an exponenial distribution.

• 한국염색가공학회지
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• 제6권3호
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• pp.37-43
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• 1994

Commercial Poly(ethylene terephthalate) (PET) filaments were treated in solvents mixtures such as benzyl alcohol/perchloroethylene(BA/PER), benzyl alcohol/trichloroethylene(BA/TRI), benzyl alcohol/ethylene chloride(BA/EC), metha nol/perchloroethylene(ME/PER), and methanol/trichloroethyle(ME/TRI). Swelling of PET in solvent mixtures showed rapidly in the middle range of mixture ratio. Contribution of swelling of each component to total swelling of binary mixtures with increasing treated time was generally showed in proportion to the mixture ratio of the each component in dependence of the extend of swelling.

• 한국항만학회지
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• 제14권1호
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• pp.57-64
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• 2000

For composing the structure model of national maritime power system by system structural modeling, in this study, the 50 basic factors are selected by survey of the extensive and through literatures on maritime, sea, maritime power and sea power. And the basic factors are classified into 36 component factors by cluster method. The 9 attributes are extracted by the application of the principle component analysis method, one of the factor analysis method in system engineering, to component factors. In this study, we define the attributes composing the national maritime power system by integrating the result of this study and existed our studies relating to this topic. Which are showed in Table 2. and we show the structure model of national maritime power system in Fig. 3. In Table 2, the 9 attributes are as follows : the fundamental power of maritime, shipping and port power, naval power, fishing power, shipbuilding power, the power of ocean research and development, dependency on seaborne trade, the protection power of ocean environment and the will and inclination of govemment. Also, in the case of evaluating this system, we conform the importance of considering the interactions among the attributes which have strong interactions in structure model of national maritime power system.

• 컴퓨터교육학회논문지
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• 제6권1호
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• pp.19-28
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• 2003

본 논문에서는 e-learning의 컨텐츠 표준화 연구에 있어 국내외적으로 관심이 집중되고 있는 ADL의 SCORM 표준을 따르는 LMS를 개발하기 위해 컴포넌트 구조에 기반한 개발 방법론을 제시한다. 또한 JSP, EJB 등 J2EE 기반의 분산 객체 컴포넌트에 기반하여 개발된 LMS인 iOneLMS를 SCORM 표준을 따르는 LMS로 변환하기 위해 제시된 방법론에 따라 SCORM 핵심 모듈을 설계하고 J2EE 기반의 EJB 컴포넌트로 구현하였다. SCORM 컴포넌트 모듈은 컨텐츠 들여오기, 강좌등록하기, 수강 및 학습 데이터 수집 등 세 모듈로 나누어 구현하도록 하였으며, 구현 과정에서 ADL 및 AICC에서 제공하는 클래스 라이브러리를 일부 재사용 하였다.

• 대한본초학회지
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• 제23권3호
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• pp.163-173
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• 2008

Objectives : Imyosan (IMS), a drug preparation comprised of Phellodendri Cortex (PC) and Atractylodis Rhizoma (AR), is commonly used as a traditional herbal medicine in Korea and China for the treatment of various inflammatory diseases. However, little is known about the effect of IMS and its component herbs on inflammatory mediators in RAW 264.7 cells. Therefore, in this study, methanol extracts of IMS and its component herbs were examined to determine if they inhibited inflammatory effects in RAW 264.7 cells. Methods : Cytotoxic activity of IJHT and its components on RAW 264.7 cells was using 5-(3-carboxymethoxyphenyl)-2H-tetrazolium inner salt (MTS) assay. The nitric oxide (NO) production was measured by Griess reagent system. And proinflammatory cytokines were measured by ELISA kit. The levels of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expression were detected by western blot. Results : Methanol extract of IMS and its component herbs were significantly reduced iNOS and COX-2 expression as well as NO, PGE2, $IL-1{\beta}$ and IL-6 production in RAW 264.7 cells. Conclusions : The results of this study indicated that the anti-inflammatory effect of Imyosan extract is more potent than that of extracts of its component herbs in macrophages.

• 한국자동차공학회논문집
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• 제14권5호
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• pp.172-180
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• 2006

This study was to analyze the effect of mixed fuel composition and mass fraction on the characteristics of evaporating diesel spray and combustion under the various ambient conditions. The characteristics of vaporization distribution and combustion were visualized by laser induced fluorescent method and direct photography. The experiments were conducted in the constant volume vessel and rapid compression expansion machine with optical access. Multi-component fuels mixed i-octane, n-dodecane and n-hexadecane were injected the vessel and rapid compression expansion machine with electronically controlled common rail injector. Experimental results show that fuel vapor formed stratified distribution. And vaporization and diffusion are become actively increasing in mass fraction of low boiling point component. Consequently multi-component fuels were expected to control the evaporating behavior according to their suitable mass fraction.

• 산업경영시스템학회지
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• 제44권4호
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• pp.98-105
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• 2021

Using the frequency-based decomposition, I decompose the consumption growth to explain well-known patterns of stock returns in the Korean market. To be more specific, the consumption growth is decomposed by its half-life of shocks. The component over four years of half-life is called the business-cycle consumption component, and the components with half-lives under four years are short-run components. I compute the long-run and short-run components of stock excess returns as well and use component-by-component sensitivities to price stock portfolios. As a result, the business-cycle consumption risk with half-life of over four years is useful in explaining the cross-section of size-book-to-market portfolios and size-momentum portfolios in the Korean stock market. The short-run components have their own pricing abilities with mixed direction, so that the restricted one short-term factor model is rejected. The explanatory power with short- and long-run components is comparable to that of the Fama-French three-factor model. The components with one- to four-year half-lives are also helpful in explaining the returns. The results about the long-run components emphasize the importance of long-run component in consumption growth to explain the asset returns.