• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2003년도 하계학술대회 논문집 B
• /
• pp.714-716
• /
• 2003

This paper deals with the characteristic analysis of a brushless DC motor (BLDC) and taking into consideration the freewheeling diodes and DC link voltage ripple using a time-stepped voltage source finite element method. By comparing with the experimental results, we show that the proposed computational method is useful for the analysis and design of a BLDC motor. We also examine the influence of freewheeling diodes and DC link voltage ripples on the performance of a BLDC motor such as torque ripples and radial force on the surface of the teeth.

• 열처리공학회지
• /
• 제7권2호
• /
• pp.103-110
• /
• 1994

It is well-known that the analysis of temperature distribution is substantilly important in optimal design of quenching process. The unsteady state temperature gradients generated during the quenching process were numerically calculated by the Finite Element Method(F. E. M.). Formulations of F. E. M. based weighted residural method were presented for the analysis of the two dimensional heat conduction problem. In the process of calculation, the temperature dependency of physical properties of the material was in consideration. At early stage of the quenching process, the abrupt temperature gradient has been shown in the surface of the carbon steel(SM45C).

• 디자인학연구
• /
• 제16권1호
• /
• pp.45-52
• /
• 2003

현대 교회건축은 그 형태와 공간의 구성 및 디자인방법에서 많은 문제점들을 보여주고 있다. 많은 교회들이 기독교적인 정체성의 표현이 결여된 채 건축되어 지고 있다. 안도 타다오의 교회건축의 특성은 전이공간, 빛과 그림자 그리고 상징의 효과적인 구성으로 나타난다. 전이공간은 한국과 일본 등의 사찰에서의 공간체험의 프로세스를 도입한 것으로 보이며 그것은 예배당을 항해 접근하는 동안 사색의 시간을 제공하며 속의 공간에서 성의 공간으로의 극적인 반전을 가능하게 한다. 안도 타다오는 자립벽을 경계로 성과 속의 공간을 구획하였다. 초기 기독교건축 이래로 빛은 교회건축의 중요한 요소였다. 안도 타다오는 현대교회건축이 잃어버린 빛과 그림자를 효과적으로 도입하여 공간의 깊이와 신성을 표현하였다. 안도 타다오에게서 상징은 모든 것이 절제되어진 그의 건축공간에서 기독교의 정체성을 나타내는 적극적이고 효율적인 표현 방법이다. 그는 상징을 건축이나 공간에 부가적인 요소가 아니라 건축과 일체가 되게 표현함으로서 공간 전체가 하나의 기독교적인 정체성을 나타내는 오브제가 되도록 하였다.

• 한국공작기계학회논문집
• /
• 제13권3호
• /
• pp.133-140
• /
• 2004

Recently reduction of industrial products in size and weight has been increased by application of micro-drills in gadgets of high precision and a great interest of a micro-drilling has been raised. Due to the lack of tool stiffness and the chip packing, the micro-drilling requires not only the robust tool structure which has not affected by vibration but also effective drilling methods designed to prevent tool fracture from cutting troubles. This paper presents an optimum design shape of a 0.15 mm micro-drill associated with a new manufacturing process to improve the production rate and to lengthen the tool life and suggestions on the micro-drilling characteristic properties associated with the tool life and workpiece quality.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 2001년도 추계학술대회(한국공작기계학회)
• /
• pp.363-368
• /
• 2001

Studies on brake system recently are focused on braking performance, especially the consideration on safety of braking system in an extreme situation and reduction of vibration and noise during braking operation. The thermal crack and Judder from the friction between brake disc and pad can bring the threaten of passengers' safety in the end. Braking force comes from the change of kinetic energy to friction energy. Since heat energy is developed from here, the analysis on thermal stress and thermal strain can be the good data when selecting the material of brake pad and designing heat radiation holes on the disc and it will also be the data when designing the thickness of the disc. This paper is intended to show a creative design method by suggesting the thermal analysis data through FEM study and using shape design parameters.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2007년도 춘계학술대회A
• /
• pp.23-27
• /
• 2007

To store hydrogen with high pressure is one of key technologies in developing FCVs (fuel cell vehicles). Especially, metal lined composite structure, which is called Type 3, is expected to effectively stand highly pressurized hydrogen since it has high specific strength and stiffness as well as excellent storage ability. However, it has many difficulties to design Type 3 vessels because of their complex geometry, fabrication process variables, etc. In this study, therefore, optimal design of Type 3 vessels was performed in consideration of such actual circumstances using genetic algorithm. Additionally, detailed finite element analysis was followed for the optimal result.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2003년도 추계학술대회 논문집(II)
• /
• pp.522-530
• /
• 2003

Generally, diaphragms are installed in the box girder to prevent or decrease the distortion of the cross section. In engineering practice, diaphragms are spaced in 5m intervals without reasonable basis. the usual diaphragm type is solid-plate type. It is considered to be noneconomical design to the almost design engineers. In this paper, the parametric study was performed to present the design proposal about the diaphragm stiffness and spacing only in the single cell box girder. For that, the distortional warping normal stress, bending normal stress and transverse bending normal stress were analyzed using finite element program 'SMB' for the accurate structural analysis.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
• /
• 한국우주과학회 2004년도 한국우주과학회보 제13권2호
• /
• pp.360-363
• /
• 2004

This review is concerned with the MP (multipactor) phenomena of the diplexer for RFDU DM of next generation satellite. The MP discharge is serious problems to design RF components in space applications such ase damage of physical structure, performance degradation, and mission failure of the satellite. In this work, we employed the 3D finite element method (FEM) to calculate the critical gap points and adopted ESTEC curve, MP susceptibility zone, to analyze the maximum handling RF power in the diplexer. And this work also recommends that one should design the tx filter of the diplexer which is more wider bandwidth upto the points to escape the ears of the group delay especially the cavity type of RF components in space applications.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
• /
• 제52권1호
• /
• pp.9-15
• /
• 2003

This Paper deals with the design of Moving Magnet type Linear Oscillatory Actuator(MM-LOA) using spring damper based on the design procedure and the characteristic analysis. MM-LOA is applied to variable load such as vaccum pump and compressor, The structure of piston type is selected to reduce a noise. MM-LOA has over-displacement in starting state because of the low inertia of mover To improve the starting characteristic, spring damper is used. The optimum spring constant of spring damper is detected and in consideration of spring damper, MM-LOA redesigned. The parameter is calculated by Finite Element Method(FEM). For the dynamic characteristic analysis, time differential method composed of voltage and kinetic equation is used. The propriety of the improved model is verified through the experimental results.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2003년도 하계학술대회 논문집 B
• /
• pp.906-908
• /
• 2003

A Linear induction electromagnetic(EM) pump of liquid metal fast breeder reactor(LMFBR) is used for the purpose that the liquid metal of high temperature is transported by EM force. This paper evaluates magnetic flux density necessary for transporting liquid metal, using analytical model of the linear induction EM pump. Using the 2-D finite element method(2-D FEM), magnetic flux density is estimated in consideration of a geometric model, electric parameter, and velocity of liquid metal. From the viewpoint of hydrodynamics, the results can be used for flow analysis of the liquid metal.