• Journal of Magnetics
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• 제18권2호
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• pp.130-134
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• 2013

Most electrical machines like motor, generator and transformer are symmetric in terms of magnetic field distribution and mechanical structure. In order to analyze these problems effectively, many coupling techniques have been introduced. This paper deals with a coupling scheme for open boundary problem of symmetric and periodic structure. It couples an analytical solution of Fourier series expansion with the standard finite element method. The analytical solution is derived for the magnetic field in the outside of the boundary, and the finite element method is for the magnetic field in the inside with source current and magnetic materials. The main advantage of the proposed method is that it retains sparsity and symmetry of system matrix like the standard FEM and it can also be easily applied to symmetric and periodic problems. Also, unknowns of finite elements at the boundary are coupled with Fourier series coefficients. The boundary conditions are used to derive a coupled system equation expressed in matrix form. The proposed algorithm is validated using a test model of a bush bar for the power supply. And the each result is compared with analytical solution respectively.

• 한국전자통신학회논문지
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• 제15권3호
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• pp.413-420
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• 2020

군 전술정보통신체계(TICN: Tactical Information and Communication Network)는 이동기지국시스템(MSAP: Mobile Subscriber Access Point)을 활용하여 음성 및 데이터 등 실시간 멀티미디어 서비스를 제공한다. 이때 소용량 무선전송체계와 대용량 무선전송체계를 통해 외부전송로를 구성하게 된다. 각 무선전송체계의 통신기기들은 전술차량에 탑재되고 전술차량에 공급전원이 통합전원제어장치로 절체 될 때 전원차단을 예방하기 위해 2차전지가 사용된다. 본 논문은 이동기지국시스템 통합제어장치 배터리 충전용 무선전력전송기기를 장하분배법을 이용하여 기본 설계하고 공극에 의한 설계 변수인 1차 측 권선 수와 코어 재질선정을 FEM(Finite Elements Method) 해석을 통해 확인하였다.

• Design & Manufacturing
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• 제14권3호
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• pp.57-62
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• 2020

In the drug delivery system industry, the technology with even split injection becomes important for maximizing efficiency and minimizing the side effects. In conventional drug delivery system, infection can occur due to pain and splashing. Also, various applications are impossible due to disposable use, and it is the reason to avoid to use this system because of the complexity of the driving method. Therefore, in this study, a painless drug delivery device is developed for non-pain with electrical insulation breakdown method. Finite elements analysis was used to evaluate the ejection characteristics of drugs according to the shape of the micro ejection nozzle. The effect of the number of holes in the micro nozzle, the length of the nozzle and the inner shape of the nozzle on the drug discharge characteristics were analyzed.

• 한국농공학회논문집
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• 제46권5호
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• pp.61-68
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• 2004

Methodologies of the finite element and boundary element are combined to achieve an efficient and accurate analysis model of frame structure containing shear wall. This model analyzes the frame by employing the finite element method and the shear wall by boundary element method. This study is applicable to a specific situation, where the boundary element is surrounded by finite elements. By employing FE dominant method in which boundary stiffness matrix is transformed into finite element stiffness matrix, boundary element and finite element method are combined to analyze frame structure with walls.

• 한국HCI학회:학술대회논문집
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• 한국HCI학회 2008년도 학술대회 1부
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• pp.78-84
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• 2008

이 논문에서는 부채꼴 모양을 가진 요소의 집합으로 3 차원 도자기 모델을 구성하고 사용자가 촉감을 느끼면서 가상공간의 도자기를 제작할 수 있도록 하는 새로운 모델을 제안한다. 변형체를 다루기 위해 기존에 사용하던 유한 요소법(finite element method)과 같은 방법은 모델이 복잡하고 연산량이 많아 실시간 햅틱 렌더링(haptic rendering)에 사용하기에는 많은 제약이 있다. 제안한 모델에서는 도자기 모양의 특징에 착안하여 부채꼴 모양을 가진 요소들이 원통 형태로 모여 쌓여있는 구조를 이용하였다. 이를 통해 요소의 개수를 줄이고 복잡한 연산을 최대한 단순화면서 효율적인 모델링이 가능하도록 하였다.

• 한국레이저가공학회:학술대회논문집
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• 한국레이저가공학회 1999년도 춘계학술발표대회 논문개요집
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• pp.29-32
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• 1999

The material properties of laser welding zone such as strength coefficient, work-hardening exponent, and plastic anisotropic ratio are analytically obtained from those of base metals based on the tensile tests. . The finite element formulation is developed for predicting strain distributions and weld line movements in the forming processes of laser welded blank. The welding zone(WZ) is modelled with the several, narrow finite elements whose material characteristics are based on the experimental results and the analytical equations. In order to show an application of the developed weld element the stamping process of auto-body door inner panel is simulated. FEM predictions are compared and showed good agreements with experimental observations.

• 반도체디스플레이기술학회지
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• 제10권3호
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• pp.61-65
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• 2011

The capabilities of finite elements codes allow now accurate simulations of blanking processes when appropriate materials modelling are used. Over the last decade, numerous numerical studies have focused on the influence of process parameters such as punch-die clearance, tools geometry and friction on blanking force and blank profile. In this study, three dimensional finite element analysis is carried out to design a lead frame blanking die using LS-Dyna3D package. After design of the blanking die, an experiment is also carried out to investigate the characteristics of blanking for nickel alloy Alloy42, a kind of IC lead frame material. In this paper, it has been researched the investigation to examine the influence of process parameters such as clearance and air cylinder pressure on the accuracy of sheared plane. Through the experiment results, it is shown that the quality of sheared plane is less affected by clearance and air cylinder pressure.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1998년도 춘계학술대회논문집
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• pp.36-39
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• 1998

To predict strain distributions and weld line movements in the forming processes of tailored blank sheets, the 2-dimensional finite element formulation is developed. The welding zone is modelled with the several, narrow finite elements. The material properties of weld elements are calculated from those of base metals, based on the experimental evaluation. To verify the finite element formulation developed, the forming process of an autobody door inner panel section is simulated. FEM predictions are compared and showed good agreements with experimental measurements.

• Structural Engineering and Mechanics
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• 제48권1호
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• pp.125-150
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• 2013

This paper intends to present an application of isogeometric analysis in crack problems. An isogeometric formula is developed based on NURBS basis functions - enriched and adopted via X-FEM enrichment functions. The proposed method which is represented by the combination of the two above-mentioned methods, first by using NURBS functions models the geometry exactly and then by defining level set function on domain, identifies available discontinuity in elements. Additional DOFs are allocated to elements containing the crack and X-FEM enrichment functions enrich approximate solution. Moreover, a subelement refinement technique is used to improve the accuracy of integration by the Gauss quadrature rule. Finally, several numerical examples are illustrated to demonstrate the effectiveness, robustness and accuracy of the proposed method during calculation of crack parameters.

• 대한기계학회논문집A
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• 제35권9호
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• pp.1091-1097
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• 2011

SGBEM-FEM 교호법은 유한 물체 내에 존재하는 삼차원 균열을 해석하는 유용한 방법으로 알려져 있다. 이 방법으로 일반적인 평면 혹은 비평면 삼차원 균열에 대한 정확한 응력강도계수를 구할 수 있다. 기존의 방법에서는 균열을 모델화 하는데 8 절점 사각형 경계요소를 사용한다. 그러나 임의 형상의 균열의 경우는 3 절점 삼각형 요소를 사용하여 균열을 모델화 하는 것이 더 편리하다. 따라서 본 논문에서는 3 절점 삼각형 요소와 7 절점 사각형 요소를 사용하여 전진 프런트 법으로 균열을 모델링 하였다. 사용된 균열 모델의 정확성을 검토하기 위하여 몇 가지 형상의 균열에 대하여 응력강도계수를 구하여 기존의 해와 비교하였다.