• 전기의세계
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• 제29권1호
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• pp.58-64
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• 1980

In this paper, this objective is to obtain the mathematical model which describes the dynamic characteristics of variable reluctance(VR) step motor, the most important and most widely used motor in practice. In the development of the mathematical model for VR step motor, first the general nonlinear dynamic equations which describe the N-phase VR step motor are derived. These general equations are then applied to the multiple-step type of VR step motor in case, for simplicity, maynetic saturation and core lossess in the iron are neglected. These nonlinear dynamic equations are numerically analysed by the computer simulation, through which the performance characteristics of a step motor undertest are investigated under the various operating conditions.

• Journal of applied mathematics & informatics
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• 제28권3_4호
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• pp.773-781
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• 2010

Recently, Yun [8] proposed a new three-step iterative method with the fourth-order convergence for solving nonlinear equations. By using his ideas, we develop a general form of multi-step iterative methods with higher order convergence for solving nonlinear equations, and then we study convergence analysis of the multi-step iterative methods. Lastly, some numerical experiments are given to illustrate the performance of the multi-step iterative methods.

• Journal of Information Technology Applications and Management
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• 제12권1호
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• pp.157-172
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• 2005

Recently, location-based service (LBS) is a hot issue in the field of computer applications. So many papers introducing new techniques of implementing a LBS and new application fields of LBS have been published recently. However, to the best of our knowledge, none of them discusses feasibility test in the prior to the implementation. The importance of a feasibility test for a design prior to the implementation cannot be overemphasized. This paper presents a method of feasibility test for a LBS design. Our method performs three steps. At the first step, we build a Petri net model of the LBS system which is depicted in natural language. The second step is to analyse the Petri net to find errors and flaws in the design. We also improve the Petri net model by fixing the errors and flaws in this step. A feasibility test is the third and final step. In this step. we verify if the design satisfies the user's requirement in the senses of quality of service (QoS) and of minimizing the implementation cost. The third step is performed in the manner of mathematical analysis of the Petri net.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2004년도 Proceedings of 2004 Korea-Japan Joint Seminar on Particle Image Velocimetry
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• pp.25-32
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• 2004

The new algorithm for higher performance of dynamic PIV has been proposed. Present study considered mathematical basis of PIV analysis for multiple-time-step images and it enables us to analyze the high time-resolution PIV, which is obtained by dynamic PIV system. Conventional single pair image PIV analysis gives us the velocity field data in each time step but it sometimes contains unnecessary information of target flow. Present technique utilize multi-time step correlation information, and it is analyzed.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2000년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 2000
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• pp.251-260
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• 2000

Seismic performance evaluation systems require rational classification of structure systems, proper evaluation criteria, and their scoring index for synthesis. Current seismic performance systems need expert judgments based on collection of available data, approximate analysis of important items, and various scoring system. This study presents a three-step seismic performance evaluation system for building structures in Korea. Each evaluation step determines the seismic performance and the method depends on the degree of refinement of analysis. The preliminary step evaluation involves the global attributes of structures such as vertical irregularity, asymmetric plan, redundancy, and age of structures. The second step requires an elastic analysis for estimation of forces acting on critical sections and checks the strength and ductility. The final step requires inelastic capacity of structures. Each stephas own evaluation scheme with proper weighing factor dependent on the importance and consequence. This study applies the fuzzy theory to a scoring method that synthesizes the individual quantity to a representative value.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 춘계학술대회 논문집
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• pp.597-601
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• 1997

The technology of Semi-Solid Forging(SSF) has been actively developed to fabricate near-net shape products using light and hardly formable materials. Generally, the SSF process is composed of slug heating,forming,compression holding and ejecting step. After forming step in SSF, the slug is comperssed during a certain holding time in order to be completely filled in the die cavity and be accelerated in solidification rate. This paper presents the analysis of temperature,solid fraction and shrinkage at compression holding step for a cylindrical slug,then predicts the solidification time to obtain the final shaped part. Enthalpy-based finite element analysis is performed to solve the heat transfer problem considering phase change in solidification.

• 한국정밀공학회지
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• 제18권10호
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• pp.93-100
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• 2001

The analysis and control of a new type unsymmetrical slotted self-bearing step motor for small angle control is presented. The motor actuator is used for both motor and bearing functionality without any additional coil windings or electromagnets for bearing functionality. A circular-arc, straight-line permeance model for the fringing effect is presented. An unsymmetrical slotted self-bearing step motor layout and control algorithm are described. A new control current generation method using the electromagnets layout geometry, which needs no additional current for bearing functionality, is proposed. As the result of this analysis the fringing effect largely influences on the system characteristics. especially in torque. Even if the bearing functionality is added into the motor functionality, it is shown that the magnitude of torque is not changed.

• 한국정밀공학회지
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• 제14권10호
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• pp.102-108
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• 1997

The technology of Semi-Solid Forging (SSF) has been actively developed to fabricate near-net- shape products using light and hardly formable materials. Generally, the SSF process is composed of slug heating, forming, compression holding and ejecting step. After forming step in SSF, the slug is compressed during a certain holding time in order to be completely filled in the die cavity and be accelerated in solidification rate. This paper presents the analysis of temperature, solid fraction and shrinkage at compression holding step for a cylindrical slug, then predicts the solidification time to obtain the final shaped part. Enthalpy-based finite element analysis is performed to solve the heat transfer problem considering phase change in solidification.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2001년도 가을 학술발표회 논문집
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• pp.193-200
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• 2001

In this study, the methodology to develop a data model for steel box girder bridge based on STEP part 104 is presented. The concept of STEP and the schema of part 104 are briefly reviewed, and then the procedure of data model standardization is described. A new data model for steel box girder bridge is developed by incorporating with not only the geometric and topological representation schema of the part 42 but also the representation structure information of the part 43 and the detailed finite element analysis information of the part 104. The prototype of integrated finite element analysis(FEA) system by interfacing STEP physical file is also presented. The applicability of developed data model for FEA is verified by preprocessor system of FEA.

• 대한치과의사협회지
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• 제56권1호
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• pp.18-40
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• 2018

Meta-analysis is a statistical method that combines the results of individual studies on the same topic. This method is becoming popular, due to providing the combined result that individual studies cannot provide and giving a more precise result. Despite meta-analysis having such significance, there were few Korean guides for the use of the Review Manager (RevMan) software. This study will provide a step-by-step guide, using orthodontic mini-screw as a dental example, to help researcher carry out meta-analysis more easily and accurately.