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박근만(Keun-Man Park),조진래(Jin-Rae Cho),전도형(Do-Hyung Jeon) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
A beam composed of two different materials are called bi-material beams. In case of bi-material beam analysis, it is very difficult to consider detailed material properties. Thus, we need to obtain approximately equivalent beam properties. In this paper, we derive equivalent material properties of bi-material beam for the efficient finite element eigen analysis. Through the comparison with three dimensional finite element model, the proposed numerical technique for bi-material beams is verified.
기계적 합금화법으로 제조된 고온 수전해용 Ni/YSZ 전극의 미세구조 특성
박근만,채의석,홍현선,추수태,Park Keun-Man,Chae Ui-Seok,Hong Hyun Seon,Choo Soo-Tae 한국재료학회 2004 한국재료학회지 Vol.14 No.10
Modified Ni/YSZ cermets for high temperature electrolysis were synthesized by the direct ball milling of Ni and YSZ powder. The ball milling was carried out in dry process and in ethanol with varying milling time. While the dry-milling decreased the average size from 65 to $80{\mu}m$, the wet-milling decreased the average size down to $10{\mu}m$. In addition, very fine particles less than $0.1{\mu}m$ were observed in the wet-milling condition. The subsequent process of cold-pressing and sintering at $900^{\circ}C$ for 2 h did not affect the particle size of dry-milled powder. The electrical conductivity of the dry-milled Ni/YSZ cermet showed the value of $5{\times}10^{2}\;S/cm$ and this value was increased to $1.4{\times}10^{4}\;S/cm$ after the sintering at $900^{\circ}C$ for 2 h.
복합단면을 갖는 비 감쇠 보 구조물의 유한요소 고유치 해석
박근만,조진래,정의봉,배수룡,Park, Keun-Man,Cho, Jin-Rae,Jung, Weui-Bong,Bae, Soo-Ryong 한국전산구조공학회 2007 한국전산구조공학회논문집 Vol.20 No.6
보 구조물의 고유치 해석의 경우 보 이론에 근거한 기존의 다양한 방법들을 통해 효율적이고 수월하게 수행이 가능하다. 하지만 보의 단면이 두 가지 이상의 복합재질로 구성되어 있을 경우 전통적인 보 이론을 적용하기 위해서는 단일의 등가 물성을 산출해야할 필요가 있다. 본 논문에서는 복합단면 보 구조물의 효율적인 유한요소 고유치 해석을 위해 등가의 물성을 산출하였다. 이론 연구를 토대로 개발한 연구용 프로그램으로 대표적인 보 구조물에 대한 유한요소 고유치 해석을 수행하였으며, 해석결과에 대한 신뢰성 검증을 위해 상용 소프트웨어인 ANSYS의 3차원 솔리드 모델의 해석결과와 비교하였다. Numerical eigen analysis of beam-like structure can be easily and effectively done by various conventional beam theory-based methods. However, in case of the structures composed of composite-sectioned beams, the application of conventional numerical methods requires one to derive both equivalent material and geometry properties. In the present paper, these equivalent properties are derived by the transformed section method and the test FEM program is coded. The numerical accuracy of the proposed method is verified through the comparison with the ANSYS 3-D model.
박근(Keun Park),박만진(Man-Jin Park),김동환(Dong-Hwan Kim),장동영(Dong-Young Jang) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6
A scanning electron microscope (SEM) is well known as a measurement and analysis equipment in nano technology, being widely used as a crucial one in measuring objects or analyzing chemical components. It is equipped with an electron optical system that consists of an electron beam source, electromagnetic lenses, and a detector. The present work concerns numerical analysis for the electron optical system so as to facilitate design of each component. Through the numerical analysis, we investigate trajectories of electron beams emitted from a nano-scale field emission tip, and compare the result with that of experimental observations. Effects of various components such as electromagnetic lenses and an aperture are also discussed.
주사 전자현미경의 이미지 해상도 향상을 위한 방안 및 실험적 검증
김동환(Dong Hwan Kim),김영대(Young Dae Kim),박만진(Man Jin Park),장동영(Dong Young Jang),박근(Keun Park) 한국생산제조학회 2007 한국생산제조학회지 Vol.16 No.5
The electric part of thermal SEM(Scanning Electron Microscopy) consists of high voltage generation, lens control, and image processing. Several methodologies for enhancing SEM image are addressed and those results are verified through analyses and experiments. The controller employes a DSP(Digital Signal Processing), making the system more flexible and convenient than the classical analogue based controller. In some parts based the analog circuit, there are inevitable sources of noise and image distortion. The experimental investigation is provided along with analytical proof to enhance the SEM image.