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3 자유도 위치 결정 기구의 위치 오차 평가 및 보정법에 대한 불확도 분석
박재준(Jae-jun Park),엄형욱(Hyungwook Eom),조남규(Nahmgyoo Cho) Korean Society for Precision Engineering 2006 한국정밀공학회지 Vol.23 No.7
This study analyzes the uncertainty of the compensation method of a sensing error of three-DOF measuring system. This compensation method utilizes a reference coordinate system using a three point by moving a position of an endpoint of a three-DOF manipulator. The coordinate transformation between the three-DOF manipulator and the measuring system is identified by the reference coordinate system. According to the concept of this compensation method, each positioning error at any position of the end-point of the manipulator is derived. Uncertainty analyses of the compensation values on the basis of sensitivity analysis and Monte Carlo simulation are used to investigate a feasibility and effectiveness of the compensation method.
외부유로 내벽에 설치된 핀 형상에 따른 이중관 열교환기의 열전달 및 유동에 대한 수치해석적 연구
박천동(Chun Dong Park),이동현(Dong Hyun Lee),박병석(Byung-Sik Park),최재준(Jaejoon Choi) 대한기계학회 2017 大韓機械學會論文集B Vol.41 No.2
본 연구에서는 이중관 지중열교환기의 내부에 삽입되는 유로의 외벽에 설치된 핀 형상에 따른 유동 및 열전달 특성의 변화를 수치해석적으로 분석하였다. 해석에는 상용 CFD 소프트웨어인 Ansys Fluent를 이용하였으며, SST k-ω 난류 모델을 적용하였다. 지중열교환기의 성능을 높일 수 있는 핀의 형상을 찾기 위하여 핀의 각도(15°, 30°, 45°, 60°), 높이비(0.1, 0.3, 0.5), 그리고 핀 간의 간격비(1, 3, 5)를 변화시키며 해석을 수행하였다. 그 결과 핀의 각도와 높이가 증가하면서 대부분의 핀 형상에서 외각유로의 외벽과 내벽에서 Nusselt 수가 증가하는 경향이 나타났다. 하지만 핀 각도 15°, 높이 비 0.3 이하의 형상에서 핀이 설치되지 않은 경우보다 외벽의 열전달계수는 증가하며 내벽의 열전달 계수가 감소하는 결과를 관찰하였다. 또한 핀 간의 간격이 감소할 경우 외벽의 열전달계수는 큰 변화가 없으나 내벽의 열전달계수는 감소하는 경향이 나타났다. In this study, the flow and heat transfer characteristics of the finned annular passage were investigated numerically. The annular passage simulates co-axial geothermal heat exchanger, and fins are installed on its inner wall to reduce heat loss from the production passage (annulus) to injection passage (inner pipe). A commercial CFD program, Ansys Fluent, was used with SST k-ω turbulence model. The effects of the geometric parameters of the fin on the inner tube were analyzed under the periodic boundary condition. The result indicated that most parameters had a tendency to increase with an increase in the height and angle of the fin. However, it was confirmed that the Nusselt number of the inner tube on the coaxial 15, 5, 0.3 was lower than that of the smooth tube. Additionally, the Nusselt number of the inner tube exhibited a tendency of decreasing with a decrease in the spacing in Coaxial 15, Sf, 0.3.
The Electrical and Mechanical Properties for Nano/Micro Alumina Composites used GIS Spacer
Park Jae Jun(박재준),Lee Kang Won(이강원),Cho Gyu Beom(조규범),Choi Jeong Wook(최정욱),Oh Seung Soo(오승수),Yoon Hyeon Mun(윤현문),Kim Young Hoon(김영훈),Park Jung Tak(박정탁),Jang Hong Joon(장홍준) 대한전기학회 2015 대한전기학회 학술대회 논문집 Vol.2015 No.11
그라인딩-호모게나이징 처리가 MFC 제조 특성에 미치는 영향
박재준(Jae-Jun Park),최경화(Kyoung-Hwa Choi),조병욱(Byoung-Uk Cho) 한국펄프·종이공학회 2018 펄프.종이기술 Vol.50 No.2
Effects of grinding and grinding-homogenizing treatments on MFC (micro-fibrillated cellulose) manufacturing characteristics were compared. MFC was manufactured by two different mechanical processes: (1) Grinding treatment only (Grinding) and (2) Homogenizing treatment after 5 passes of grinding (Grinding-Homogenizing). And then characteristics of MFCs produced were evaluated. It was found that the grinding-homogenizing treatment can improve fibrillation efficiency compared with the grinding treatment. The grinding-homogenizing treatment produced MFC with higher slurry viscosity and WRV than that with the grinding. In addition, the CED viscosity and the crystallinity index of MFC produced with the grinding-homogenizing process were higher than that with the grinding process at a given MFC slurry viscosity, implying that a high quality MFC could be produced with the grinding-homogenizing process. No distinct differences in crystalline and chemical structure were observed between the MFCs produced with different processes and different pass numbers.
고점도형 고상에폭시/실리카와 알루미나 콤포지트의 전기적, 기계적 특성연구
박재준(Jae-Jun Park) 대한전기학회 2018 전기학회논문지 Vol.67 No.10
In this study, 40, 50, 60, and 70 wt% filler dispersed samples were prepared for the current GIS Spacer or environmentally friendly GIS. In the AC electrical breakdown, EMSC and EMAC decreased with increasing filler content, and EMSC showed better breakdown strength than EMAC. The mechanical properties such as tensile strength and flexural strength of EMSC and EMAC were also increased with increasing filler content. In addition, EMSC results in better mechanical properties than EMAC. The reason for this is considered to be one in which the influence of the interface is important.