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Suppression of thermal deformation of machine tool spindle using TiC-Fe composite
Wonjun Bae,Junghwan Kim,Seungchan Cho,김양진,이상관 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.5
The minimization of error generation in machine tool spindle is important because high-speed and ultra-precision machining are extensively utilized in industrial fields. The thermal deformation of the machine tool spindle generated by the frictional heat between the outer and inner bearings can deteriorate the machining accuracy. In this study, a TiC-SUS431 composite was fabricated using the liquid pressing infiltration method to suppress thermal deformation, and its thermal properties were obtained by thermal characteristic tests. For the transient thermal analysis with finite element analysis, the parameters of the machine tool spindlebearing model were selected, and the boundary conditions were calculated. The temperature and thermal deformation of the analysis model were compared by applying SCM415 and TiCSUS431 to the material of the machine tool spindle and changing the rotation speed. From the analysis results, it was demonstrated that the TiC-SUS431 machine tool spindle can improve the machining accuracy by minimizing the spindle thermal deformation.
Phase extraction formula for glass thickness measurement using Fizeau interferometer
Wonjun Bae,김양진 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.4
The thickness variation of transparent optical flats has become a crucial parameter owing to the development of display and semiconductor technologies. Systematic offset phase errors can be generated when the absolute thickness of samples is profiled using a Fizeau interferometer. In this study, a novel 11-sample phase extraction formula was developed to suppress offset phase errors during thickness measurements. The newly developed 11-sample formula was visualized on the frequency domain and complex plane by using Fourier description and the algorithmic polynomial theory. The offset error compensation capability of the 11-sample formula was confirmed based on the results of a numerical analysis. Finally, the glass thickness was measured using a wavelength-scanning Fizeau interferometer and the proposed 11-sample formula. The standard deviation was 9.654 nm, which demonstrates the superior capability of this formula.
Suppression of machine tool spindle vibration using TiC-SKH51 metal-matrix composite
Wonjun Bae,김성태,김양진,Sang-Kwan Lee 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.8
The generation of machine tool spindle vibration is becoming prevalent as high-speed machining and lightweight design are being actively applied in the machining process. As the required machining accuracy increases, the machine tool spindle vibration generated in ultra-precision machining is the main cause of the deterioration of the machining quality. In this study, a TiC-SKH51 metal-matrix composite was used to suppress the machine tool spindle vibration. A vibration characteristic test was conducted to obtain the dynamic characteristics of the TiC-SKH51 and other testing materials. By comparing the results of the vibration characteristic test, the reliability of the finite element analysis software was confirmed. Then, dynamic and static analyses were performed to obtain the dynamic and static characteristics of the machine tool spindle model. The analysis results show that the TiC-SKH51 machine tool spindle can directly suppress the generation of spindle vibrations.
전자정부사업 역량강화 연수의 미시적 효과 : 나이지리아 전자정부 사업 사례연구
배원준(Wonjun Bae),장우찬(Woochan Chang) 한국국제협력단 2019 국제개발협력 Vol.14 No.2
본 연구는 나이지리아 전자정부 역량강화사업의 연수과정을 소재로, 역량강화 연수가 참가자 개인에 미치는 영향과 전자정부 사업의 목표인 업무 재설계(Government Process Re-Engineering)를 달성하는 데 필요한 조건을 확인하였다. Kirkpatrick(1994)의 이론에 따라 개인의 교육훈련 효과를 (1) 교육 과정에 대한 만족도, (2) 교육을 통해 얻게 된 기능, 태도 또는 지식, (3) 실제 일어난 행동 변화, 즉 교육장에서 배운 지식의 현업 활용도, (4) 교육과정 참가로 인해 교육 참가자가 창출하는 조직 차원의 성과로 나누어 보았으며, 맥니마 분석을 통해 연수과정이 참가자의 자기효능감을 유의미하게 증대시키는 것을 확인했다. 다중회귀분석을 활용해 현업 활용도의 증대요인을 분석한 결과, 부처의 정보화 수준이 가장 중요한 것으로 드러났으며, 이는 초점집단면접을 통해서도 확인되었다. This study aimed to assess the impact of an e-government training on individuals and to identify the conditions required for the training to achieve re-engineering of the government process, which is the objective of the e-government projects. We focused on the case of “Capacity Building of e-Government in Nigeria” by the Korea International Cooperation Agency. Adopting the theory of Kirkpatrick (1994), we collected and analyzed data by gauging (1) satisfaction, (2) knowledge, skills, or attitudes, (3) actual transfer or implementation, and (4) change at the organizational level derived from the training. We confirmed through a McNemar Test that the training improved the self-efficacy of the participants to a significant extent. By correlation and multivariate regression analyses, we found that the informatization level of the department is the most important factor in the training transfer.
공간 균일 오차 최소화가 가능한 위상 시프팅 알고리즘을 통한 광학 두께 변동량 측정
배원준(Wonjun Bae),김양진(Yangjin Kim) 대한기계학회 2019 대한기계학회 춘추학술대회 Vol.2019 No.11
Wavelength-tuning interferometry is an effective means of detecting the intensity signals necessary to obtain thickness information, particularly the optical thickness variation of transparent plates. The phase-shift error caused by the non-linearity of a phase-shift can lead to spatially uniform error. When the absolute optical thickness is measured, this could be a significant error source. In this study, we developed a new 19-sample phase-shifting algorithm that can suppress spatially uniform error and harmonic components up to the sixth order. Utilizing the Taylor expansion and symmetric/asymmetric properties, we created a new sampling window. The absence of an equation is solved by adjusting the first and second value of sampling window. Finally, the characteristics of the new 19-sample phase-shifting algorithm are shown by analyzing the Fourier transform of sampling functions, phase-dependent measurement errors, and the root mean square (RMS) error.
Anticariogenic β-Carboline Alkaloids from Commelina communis
Bae, Kihwan,Seo, Wonjun,Kwon, Taeho,Baek, Soohyun,Lee, Shinwoong,Jin, Kapduck 충남대학교 약학대학 의약품개발연구소 1992 藥學論文集 Vol.8 No.-
The methanolic extract of Commelina communis (aerial part) showed antibacterial activity aganist a cariogenic bacterium, Streptococcus mutans OMZ 176. The active principles were identified to be β-carboline alkaloids, 1-carbomethoxy-βcarboline, norharman and harman, which were bactericidal in the minimal inhibitory concentration (MIC) of 100 ㎍/㎖ against the strain.
Bae, Kihwan,Yoo, Beongtae,Lee, Myungkoo,Seo, Wonjun 충남대학교 약학대학 의약품개발연구소 1985 藥學論文集 Vol.1 No.-
It was revealed that magnolol and honokiol isolated from the stem bark of Magnolia obovata, had potent antibacterial activity against Bacillus anthracis. A quantitative analytical method of magnolol and honokiol by HPLC has been established, and the amounts of the two components in the dried stem bark of M. obovata were 1.94%, and 0.44%, respectively.
배기환,서원준 충남대학교 약학대학 의약품개발연구소 1994 藥學論文集 Vol.10 No.-
7,8-Dioxo-A-norerythrinan (A) was synthesized from acid catalyzed cyclization of 6a-hydroxy-1-(2-phenylethyl)-octahydrocyclo-penta[b]pyrrole-3a-caboxylic acid ethyl ester (B) with concomitant deethoxycarbonylation. The intermediate (B) was a hydroxylated compound of N-acyliminium (C). The unstable pyrrolinium (C) was prepared from oxalylation of the enamine of phenethylamine and ethyl 2-oxocyclopentanecarboxylate.