• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.17 no.2
• /
• pp.193-201
• /
• 2004

The aim of this study is focused on getting an almost exact solution which is the simplicity and exactness of an axisymmetrically loaded cylindrical shell. This method replaces the finite element method which is a very powerful tool for analysis of any kind of structure which has an arbitrary shape, but is still a numerical analysis. Instead, this study uses the method of distribution of end actions which is a kind of iteration technique to implement the leading matrix method. The distribution and carry-over factors of a cylinder are calculated by the theory of a differential equation of a beam on an elastic foundation. The results are satisfactory when this method is applied to a cylinder that is subjected to a concentrated load and hydrostatic pressure when compared with the BEF analogy separately.

• Current Optics and Photonics
• /
• v.3 no.2
• /
• pp.154-163
• /
• 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
• /
• v.9 no.2
• /
• pp.232-242
• /
• 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
• /
• v.14 no.4
• /
• pp.1007-1012
• /
• 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
• /
• v.57 no.2
• /
• pp.211-222
• /
• 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
• /
• v.4 no.1
• /
• pp.1-4
• /
• 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
• /
• v.2 no.1
• /
• pp.77-82
• /
• 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.

• Journal of Korea Technology Innovation Society
• /
• v.20 no.3
• /
• pp.781-804
• /
• 2017

Video surveillance industry as a high-tech industry has traits that a pace of source technology development is slow while a pace of application technology development is fast. Unlike domestic companies have shown technological excellence in the field of video surveillance hardware, global leading companies are leading technologies in the field of intelligence video surveillance which would lead the future of the industry. Therefore, technology selection of the domestic companies determines the viability of the company with respect to the terms of market competitiveness reinforcement. In order to achieving this, find out the technology areas where the global leading companies are focused on analysis of global patents. After global patents analysis, identify the status of domestic technologies and analyze the difference between the global leading companies and the domestic companies. Decompose the technologies by element technology-application matrix which is obtained through a panel discussion of domestic SMEs' CTO, CEO, or other experts, they derive the necessary R&D opportunity technologies to ensure the future competitiveness of the company.

• Journal of the Korean Operations Research and Management Science Society
• /
• v.36 no.4
• /
• pp.29-41
• /
• 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.

• The Research Journal of the Costume Culture
• /
• v.15 no.3 s.68
• /
• pp.525-540
• /
• 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.