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진동의 주파수분석을 통한 결함 식별 - 회전기계를 중심으로-
정윤성,왕지남,김광섭,Jeong, Yoon-Seong,Wang, Gi-Nam,Kim, Gwang-Sub 한국정밀공학회 1995 한국정밀공학회지 Vol.12 No.11
This paper pressents a condition-based maintenance (CBM) method through bibration analysis. The well known frequency analysis is employed for performing machine fault diagnosis. The statistical control chart is also applied for analyzing the trend of the bearing wear. Vibration sensors are attached to prototype machine and signals are continuously monitored. The sampled data are utilized to evaluate how well the fast fourier transform(FFT) and the statistical control chart techniques could be used to identify defects of machine and to analyze the machine degradation. Experimental results show that the propowed approach could classify every mal-function and could be utilized for real machine diagnosis system.
GLOBAL EXISTENCE OF WEAK SOLUTIONS FOR A KELLER-SEGEL-FLUID MODEL WITH NONLINEAR DIFFUSION
정윤성,강경근,김재우 대한수학회 2014 대한수학회지 Vol.51 No.3
We consider the Cauchy problem for a Keller-Segel-fluid mo- del with degenerate diffusion for cell density, which is mathematically formulated as a porus medium type of Keller-Segel equations coupled to viscous incompressible fluid equations. We establish the global-in- time existence of weak solutions and bounded weak solutions depending on some conditions of parameters such as chemotactic sensitivity and consumption rate of oxygen for certain range of diffusive exponents of cell density in two and three dimensions.
실리콘 단결정 잉곳용 석영유리 도가니의 brownish ring에 대한 연구
정윤성,최재호,민경원,변영민,임원빈,노성훈,강남훈,김형준,Jung, YoonSung,Choi, Jae Ho,Min, Kyung Won,Byun, Young Min,Im, Won Bin,Noh, Sung-Hun,Kang, Nam-Hun,Kim, Hyeong-Jun 한국결정성장학회 2022 한국결정성장학회지 Vol.32 No.3
A brown ring (hereinafter referred to as BR) on the inner surface of a quartz glass crucible used in the manufacturing process of a silicon ingot for semiconductor wafers was studied. BR is 20~30 ㎛ in size and has an asymmetric brown ring shape. The size and distribution of BR were different depending on the crucible location, and the size and distribution of BR were the largest and most abundant in the round part with the highest crucible temperature during Si ingot growth. BR contains cristobalite, which has a higher coefficient of thermal expansion than quartz glass, so it is considered that surface cracks appear. The color development of BR and pin holes are presumed to be due to oxygen vacancies.
5년간 울산대학교병원에서 HPLC법을 이용한 Mycobacteria의 동정과 균종 분포
정윤성,김성률,장철훈,이선호 대한진단검사의학회 2008 Annals of Laboratory Medicine Vol.28 No.1
Background : Infections caused by mycobacteria have been significantly increasing. Due to the difficulty of making a decision about the pathogenicity of mycobacteria, species-level identification is very important for patients’ diagnosis and treatment. The purpose of this study was to identify mycobacteria species using a high performance liquid chromatography (HPLC) method and to provide an initial database for the distribution of mycobacteria in Korea. Methods : Acid fast bacteria isolated from 3,107 clinical specimens were identified by mycolic acid analysis using HPLC. The HPLC patterns were compared with those of standard mycobacteria species. Results : The HPLC patterns were divided into single, double, and triple cluster groups, each group comprising 9, 20, and 4 species, respectively. Mycobacteria and non-tuberculous mycobacteria (NTM) were identifies by HPLC at the rates of 99.5% and 95.6%, respectively. NTM was isolated in 12.4% of the mycobacteria positive specimens. This study also found that there were 20 different NTM species with the distribution of each species ranging from 0.3% to 15.9% of the total NTM. While the rate of NTM has been increasing in Korea, M. avium-intracellulare, M. fortuitum, and M. chelonae are relatively decreasing, and M. kansasii and M. gordonae are relatively increasing. Conclusions : HPLC method was highly discriminative for the identification of NTM in clinical specimens. (Korean J Lab Med 2008;28:24-33)