• 소성∙가공
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• 제4권3호
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• pp.267-281
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• 1995

Preform design is one of the critical fields in metal forming. The finite element method(FEM) has been effective in designing preforms and process sequence, for which the backward tracing scheme of the rigid-plastic FEM has been explored. In this work a program using the backward tracing scheme by the rigid-plastic FEM is developed for three-dimensional plastic deformation, which is an extension of the scheme from two-dimensional cases. The calculation of friction between workpiece and die, and handling of boundary conditions during backward tracing require sophisticated treatment. The developed program is applied to upsetting of a rectangular block and to side pressing of a cylindrical workpiece. The results of the two applications show feasibility of the program on three-dimensional plastic deformation.

• 한국공작기계학회논문집
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• 제13권2호
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• pp.40-46
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• 2004

Magnetic bearing has been adopted to support a rotor by electromagnetic force without mechanical contact and lubrication process. The recent growth of magnetic bearing applications in many industrial fields requires more accurate design of bearing-rotor system. Due to external forces and uncertainties of magnetic bearing system the actual performance and stability my be worse than it is designed. This paper describes the governing equations of rotor magnetic bearing systems and/or the designing of robust controller via standard $H_{\infty}$ control problem. The system stability and response characteristics are studied by simulations and verified with experimental results.

• 한국정밀공학회지
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• 제8권3호
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• pp.55-63
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• 1991

Transforming small ultrasonic energy into large mechanical energy is the essential feature of ultrasonic vibration in various application fields. This energy amplification can be obtained by achieving resonance condition between booster or tool horn and transducer. When it has uniform section with small sectional area, one dimensional analysis provides good estimation of the natural frequency of the horn. But, for arbitrary shape of horn, one dimensional analysis can no longer be applied. At present, designing tool horn whose natural frequency is identical to that of transducer requires serveral stages of trial and error in actual manufacturing process. In this paper, frequency analysis program is developed to easily predict the natural frequency of ultrasonic vibration cutting tool with axisymmetry and 3- dimensional shape using finite element method.

• 세라미스트
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• 제21권2호
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• pp.49-58
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• 2018

Metal oxide based materials have been widely used to fields of electrochemical applications. Recently, various type of defects from microstructures of metal oxides and their nanocomposites have been raised as the important material design factors for realizing highly improved electrochemical properties. Previous experimental and theoretical works have suggested that controlling the reaction activity and kinetics of the key electrochemical reactions by activated interfaces originating from the defect sites can play an important role in achieving the robust energy storage and conversion. Therefore, this paper focuses on the role of defect-controlled metal oxide materials such as doping, edge-sites, grain boundaries and nano-sized pores for the high performances in energy storage devices and electrocatalysts. The research approaches demonstrated here could offer a possible route to obtain noble ideas for designing the metal oxide materials for the energy storage and conversion applications.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 B
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• pp.817-818
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• 2006

A 2.0T class HTS conduction cooled magnet was designed. Designing of magnet shape was performed through two steps. First step is to find a basic cross section for minimize the amount of conductor used and second step to optimize the coil shape to satisfy the magnetic field homogeneity. The magnetic fields was analyzed with FEM and the critical current value of magnet was also expected with the result of field analysis and the Ic to B curve of Bi-2223 HTS tape.

• 항공우주시스템공학회지
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• 제4권4호
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• pp.18-27
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• 2010

Quadrotor is an aircraft which is possible in Vertical Take-off and Landing(VTOL). This aircraft can not only be created as an Unmanned Aerial Vehicle(UAV), but also can be easily used in various fields because of its simplicity of construction. This study is mainly conducted with two main purposes. The first goal is designing the quadrotor focusing on the lightweight and protecting the airframe. The second purpose is stabilizing the quadrotor's attitude by using the PID controller. MATLAB simulation is performed for obtaining PID gain based on equations of motion. We used the compensation filter technique for the calibration of sensor data. PID gain has been drawn out based on the MATLAB simulation. The efficiency of the attitude control is improved by calibration of sensor data.

• 설비공학논문집
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• 제5권1호
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• pp.27-34
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• 1993

The two-stage electrostatic air cleaner is a particle control device that uses electrical forces to move particles in the flowing gas stream onto collector plates. Despite a general understanding of electrostatic air cleaner operation and their successful use in industry, many questions regarding flow, electric fields and particle collection have remained unanswered. In this paper, an experimental investigation for designing the discharge electrode, including ionizer wire diameter, plate length and wire-to-plate spacing, is carried out. The electrical conditions, namely the electric field intensity, the space current and the particle charge intensity, in wire-plate electrostatic air cleaner are reported and examined.

• 한국정보과학회논문지:소프트웨어및응용
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• 제28권12호
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• pp.921-929
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• 2001

PCL(Object Constraint Language)은 UML, 메타모델을 정밀하게 명세화하기 위해서 UML 의미론의 도큐먼트에 사용되어졌다. 피리고 UMLl-은 실시간 UML 웹 개발 UML 등과 같이 다양한 시스템을 개발하기 위해서 확장되었다. 특히 실시간 시스템을 개발할 때 적시성, 동시성, 예측성, 신뢰성이 고려되어야 한다 이에 따라 실시간 UML을 정밀하게 표현하고 구현을 쉽게 하기 위해서 OCL을 사용해야 하지만 현재의 OCL로 실시간을 묘사하기에는 부적합하다. 본 논문에서는 실시간 시스템을 개발하는데 있어서 실시간 언어고 쉽게 변환이 가능하도록 이벤트 위주로 실시간 OCL을 제안하였고 그 효용성의 검증으로서 권선기 시뮬레이터 개발에 응용하였다.

• Journal of Information Technology Applications and Management
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• 제16권1호
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• pp.77-96
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• 2009

The balanced scorecard has drawn attention from many researchers in various fields since its appearance in 1992. It became a norm for performance evaluation framework in many areas, such as marketing, information system evaluation, strategic planning, etc. Centered in the large companies in Korea, the balanced scorecard has been popularly used as a performance evaluation tool for human resource management. Now we Question its applicability to performance evaluation tool even in small business. This study tried to apply the balanced scorecard in developing an information system for performance evaluation in a small business. The study showed that the balanced scorecard can be nicely used in small business as a performance evaluation tool. The process of developing an information system is described in detail. The practitioners are to obtain a lot of insights in designing their human resource management systems from the study results.

• 한국실내디자인학회논문집
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• 제27호
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• pp.168-175
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• 2001

This study focuses to enhance the general understanding on the new approach and to provide a clue for a new paradigm in man-made physical and residential environment of the 21st Century. Through case analysis, this study aims to examine the characteristics of digital culture itself and of its physical and residential environment and to ultimately forecast the changeability of physical and residential environment prompted by the new digital wave. Without having precedent study about digital culture related to environmental issues, this study aimed to analyze the effect of digital culture in the field of physical environment and residential environment, and to forecast the changability in those fields. On the other hand, this study also atoned to be applicable in construction of a new paradigm in designing physical & residential environment in the near future, so as to contribute to the development of a new environment which will eventually improve the quality of human life.