• 한국전산구조공학회논문집
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• 제17권2호
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• pp.193-201
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• 2004

본 연구의 목적은 축대칭 하중을 받는 원통형 펄의 엄밀해를 구하는데 있어서, 간략하면서도 엄밀한 해를 구하는 방법을 제시하고자 하는데 있다. 이는 임의 형상의 구조해석을 위한 강력한 도구이긴 하지만 여전히 근사해석인 유한요소법에 대체될 수 있을 것이다. 이를 위해 본 논문은 반복법의 일종인 인도행렬법을 이용한 절점역계의 분배방식을 사용하였다. 원통형 쉘의 분배와 전달인자는 한성지반상의 보에 대한 미분방정식으로부터 구해진 것이다. 이러한 방법을 축대칭 집중하중과 정수압을 받는 원통형 쉘에 각각 적용해 보았고, 그 결과는 BEF 이론해와 비교할 때 만족할 만 하였다.

• Current Optics and Photonics
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• 제3권2호
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• pp.154-163
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• 2019

In this study, we developed an optical sighting system capable of shooting at a long-distance target by operating a digital gyro mirror composed of a gyro sensor and an FSM. The optical sighting system consists of a reticle part, a digital gyro mirror (FSM), a parallax correction lens, a reticle-ray reflection mirror, and a partial reflection window. In order to obtain the optimal volume and to calculate the leading angle range according to the driving angle of the FSM, a calculation program using Euler rotation angles and a three-dimensional reflection matrix was developed. With this program we have confirmed that the horizontal leading angle of the developed optical sighting system can be implemented under about ${\pm}8^{\circ}$ for the maximum horizontal driving angle (${\beta}={\pm}12.5^{\circ}$) of the current FSM. Also, if the ${\beta}$ horizontal driving angle of the FSM is under about ${\pm}15.5^{\circ}$, it can be confirmed that the horizontal direction leading angle can be under ${\pm}10.0^{\circ}$. If diagonal leading angles are allowed, we confirmed that we can achieve a diagonal leading angle of ${\pm}10.0^{\circ}$ with a vertical driving angle ${\alpha}$ of ${\pm}7.1^{\circ}$ and horizontal driving angle ${\beta}$ of ${\pm}12.5^{\circ}$.

• Journal of Power Electronics
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• 제9권2호
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• pp.232-242
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• 2009

In this paper, a matrix converter with improved low frequency output performance is proposed by achieving a one-step commutation owing to a general commutation circuit applicable to n-phase to m-phase matrix converters. The commutation circuit consists of simple resister and capacitor components, leading to a very stable, reliable and robust operation. Also, it requires no extra sensing information to achieve commutation, allowing for a one-step commutation like a conventional dead time commutation. With the dead time commutation strategy applied, the distortion caused by commutation delay is analyzed and compensated, therefore leading to better output linear behavior. In this paper, detailed commutation procedures of the R-C commutation circuit are analyzed. A selection of specific semiconductor switches and commutation circuit components is also provided. Finally, the effectiveness of the proposed commutation method is verified through a two-phase to single-phase matrix converter and the feasibility of the compensation approach is shown by an open loop space vector modulated three-phase matrix converter with a passive load.

• Journal of the Korean Data and Information Science Society
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• 제14권4호
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• pp.1007-1012
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• 2003

A recursive procedure for finding the Cholesky root of the inverse of sample covariance matrix, leading to a direct solution for the inverse of a positive definite matrix, is developed using the likelihood equation for the maximum likelihood estimation of the Cholesky root under normality assumptions. An example of the Hilbert matrix is considered for an illustration of the procedure.

• Kyungpook Mathematical Journal
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• 제57권2호
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• pp.211-222
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• 2017

In this paper, we consider three inverse eigenvalue problems for a special type of acyclic matrices. The acyclic matrices considered in this paper are described by a graph called a broom on n + m vertices, which is obtained by joining m pendant edges to one of the terminal vertices of a path on n vertices. The problems require the reconstruction of such a matrix from given partial eigen data. The eigen data for the first problem consists of the largest eigenvalue of each of the leading principal submatrices of the required matrix, while for the second problem it consists of an eigenvalue of each of its trailing principal submatrices. The third problem has an eigenvalue and a corresponding eigenvector of the required matrix as the eigen data. The method of solution involves the use of recurrence relations among the leading/trailing principal minors of ${\lambda}I-A$, where A is the required matrix. We derive the necessary and sufficient conditions for the solutions of these problems. The constructive nature of the proofs also provides the algorithms for computing the required entries of the matrix. We also provide some numerical examples to show the applicability of our results.

• Journal of Magnetics
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• 제4권1호
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• pp.1-4
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• 1999

The microstructure and magnetic properties of$ Fe_{87}Zr_7Si_4B_2$ nanocrystalline alloys were studied by magnetization measurements and M ssbauer spectrometry over a wide temperature range. Three well resolved spectral components have been found and attributed to bcc-Fe grains (with almost pure iron structure), residual amorphous matrix enriched with solute elements and interfaces formed at the grain-matrix boundaries. It has been shown that, contrary to the expectation, during crystallization the atomic segregation occurs leading to the formation of primary bcc-Fe grains and the partition of Si atoms into the residual amorphous matrix.

• Journal of international Conference on Electrical Machines and Systems
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• 제2권1호
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• pp.77-82
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• 2013

By using simulation, compensating characteristics of a voltage sag compensator utilizing single-phase matrix converter is examined. System configuration is described and mathematical model of single-phase matrix converter is derived by using the state space averaging method. In addition, the single-phase matrix converter is stabilized by phase-lead compensation. Finally, compensating characteristics of the compensator is investigated for 500 W R-L load and it is demonstrated that the compensator can operate correctly for loads for the range of power factor 0.6 (lagging) - 0.8 (leading) and for up to 50% voltage sag.

• 기술혁신학회지
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• 제20권3호
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• pp.781-804
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• 2017

영상 보안 분야는 하이테크 산업이면서 원천기술의 발전 속도는 느리고 응용 기술 분야의 발전 속도는 빠른 특징을 지니고 있는 것으로 알려져 있으며, 영상 보안 하드웨어 관련 분야에서의 국내 기업들의 기술 수준은 높으나 이를 이용한 응용 시스템 분야의 기술 수준은 그렇지 못한 실정이다. 국내 영상산업 분야 기업들의 기술 선택은 시장 경쟁력 강화라는 측면에서 해당 기업의 생존 가능성을 결정한다. 본 논문에서는 지능형 영상 보안 산업 분야의 국내 기업들을 위하여 장기적인 기술경쟁에서 원천 기술을 획득하기 위한 기술의 선택 방법을 제안한다. 이를 위하여 글로벌 선도기업의 특허 현황 분석을 통하여 그들이 집중하는 기술 분야를 확인하고, 국내 기술의 현황을 파악하여 선도기업과의 차이를 분석하였다. 또한, 국내 중소기업의 CTO와 CEO등 전문가들과의 패널토론을 통하여 조사한 기술과 제품의 미래시장 규모를 추정하였으며, 요소기술-응용제품 매트릭스 기법을 이용하여 기술의 중요성을 평가하여 R&D 기회 기술선택방법을 제안하였다. 본 연구의 성과를 통하여 영상 보안 산업분야의 중소기업이 선택과 집중이 가능한 기술 획득을 추진함으로서 기술사업화 성과를 제고 할 수 있을 것으로 기대한다.

• 한국경영과학회지
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• 제36권4호
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• pp.29-41
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• 2011

As industires are evolving into a more advanced type industrial system, service economy has been more emphasized. But with the expansion of the service economy, the failure of the service has also increased. Customers flee caused by the service failure leads to from simple problems like financial loss to serious problems like damaging corporate image. Therefore, if possible, the system providing defect-free service should be established. If this is not possible, preventive measures should be taken in order to minimize the failure. The study as a tool to prevent service failure presents the concepts "service error matrix." And to confirm whether this idea is practical or not, this study investigated the hotel, one of the leading service industries, about actually occurring service failure and applied to service error matrix suggested in this study. Finally service blueprint and Poka-yoke are completed in order to reduce service failure of Y hotel which was the object of the interview for this study.

• 복식문화연구
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• 제15권3호
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• pp.525-540
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• 2007

This study intended to construct the brand switching matrix in the Korean casual wear market and to analyze it in various aspects. 1,014 sample data were collected in Seoul area, a center of fashion retailing. Since the respondents cited over 200 brand names as their last 2 purchased casual wear brands, 15 most frequently-purchased brands were selected for constructing the brand switching matrix. As a result of the examination, it was founded that the brand loyalty was dominant rather than brand switching in the casual wear market. Polo was identified as the leading brand in the market. Its brand equity, which was comprised of brand recognition, brand preference (loyalty), perceived quality, and brand association, was evaluated very high. Especially, the strength of Polo was the consumer's strong preference and the brand image of simplicity, naturalness, and neatness. After combining 15 brands into 6 groups based on the style and price, additional interpretation was performed on this 'trend switching matrix.' A transition of fashion trend in casual wear was observed. Applying the brand switching matrix on fashion products gave us much insight to the market.