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김현곤,이동희 경성대학교 공학기술연구소 2012 공학기술연구지 Vol.18 No.-
본 논문에서는 전력 용량 10kW급의 새로운 양방향 PWM Sepic/Zeta 회로를 사용한 컨버터를 제안한다. 이 회로를 설계하고, 이 컨버터의 설계가 동작 가능한지에 Matlab의 Simulink를 사용하여 시뮬레이션 하였다.
평면연삭에서 숫돌의 종류와 연삭조건에 따른 표면거칠기 및 연삭숫돌의 파괴
오동석,이병곤,이종훈 한국공작기계학회 2001 한국생산제조학회지 Vol.10 No.4
In this study, the variation of surface roughness was tested in surface grinding for the three winking materials SM45C, heat-treated SM45C, and gray cast iron. It was performed for the various grinding wheels with two grain size #60, #100, and three grade I,O,R and various grinding depths and feeds. The fractural grinding depths which were obtained when the grinding wheels were destructed in surface grinding works, were examined and compared with the calculated value sug-gested in this study. The results showed that the surface roughness was decreased by decreasing grinding depth, and feed, and increasing grain size and grades. The fracture grinding depths were increased by increasing grain size, grade and feed.
김일곤,유동선 昌原大學校 基礎科學硏究所 2001 基礎科學硏究所論文集 Vol.13 No.-
We have measured the absorption spectrum of CuBr quantum dots at 8.5K. Z1.2 exciton peak moves toward the shorter wavelength relative to the bulk CuBr. After a selective excitation by the dye laser, we could find the spectral hole in the absoprption spectrum. The depth and width of spectral hole depends on the optical fluence of dye laser. There are two process in the hole burning of quantum dots. The rising times of hole depth are 1.2 sec and 250 sec respectively. We think that the fast process is the result of the reduction of quantum dots which have the specific mean diameter, the second process is caused by the variation of a environment of matrix.
오동석,이병곤 한국산업안전학회 2002 한국안전학회지 Vol.17 No.4
In this study, the fracture characteristics of carbonized silicon grinding wheels were examined with tensile, compression, impact and bending test. The experiment was performed for the various grinding wheels with grain size #46, #80, and grade H, L, P, and one vitrified bond and one structure No. 7. Also the centrifugal fracture rpm of carbonized silicon grinding wheels were measured and compared with the calculated values for the various wheel diameters and thicknesses. The results showed that the fracture tensile strength was 1.5~2.0㎏/㎟, and it was increased by decreasing grain size and increasing grade. The fracture compression loads were 1,600~3,000㎏_f, and the inner stress was higher than outer's. And the abosrption energy of impact test was 3.3~4.7 J, and it was increased by decreasing grain size but it was not effected by grade. The fracture bending stress was 0.1~0.2㎏/㎟, and it was increased by decreasing grain size and increasing grade. The centrifugal fracture rpm of carbonized silicon grinding wheel was about 8,500~12,000 and agreed well with the calculated value, and it was increased by decreasing diameter. However, it was almost constant for the reduction of wheel thickness.
서울시 토양 중 다환방향족탄화수소의 농도특성에 관한 연구
김동환,옥곤 한국환경과학회 2005 한국환경과학회지 Vol.14 No.1
Soil is one of the most fundamental elements as well as with water and air in studies associated with the environment, in addition. it is one of the important environmental mediums that constructs a basis of the biological system and performs various roles of matter circulation. This study was carried out in Seoul, in May 2000 to evaluate variation in the concentration levels and distribution characteristics for PAH compounds in soil. Soil samples were collected from 33 sites covering traffic, factory, incineration and mountain groups and the PAHs were analyzed. The results show a wide distribution range of PAHs concentrations between 14.66 ng/g and 1,219.35 ng/g. The highest concentration levels exist at Sungsu-2 of the factory group (FS-2). Daemo-3 of the Mountain group (MD-3) presents the lowest levels as compared with the other sites. PAH compounds including mutagenic and carcinogenic materials show high concentrations in the traffic and factory groups and a high ratio in the mountain group. Besides, these compounds absorbed with micro particles might be spread out over a wide region associated with particles' movement and diffusion. After principal component analysis of the soil samples, the results indicated that the sources of PAHs in the soil were divided into two groups, pesticides and vehicles.
탄소섬유 프리프레그 외부 표면 적층방법에 따른 하이브리드 샤프트 진동특성
홍동표,김현식,홍용,고유곤,유청환 한국공작기계학회 2009 한국공작기계학회 춘계학술대회논문집 Vol.2009 No.-
Studies on carbon fiber epoxy composite is being conducted broadly in industries because of its specific stiffness, specific strength and good fatigue resistance. Because carbon fiber epoxy composite has high vibration characteristics, if existing metal material is alternated by carbon fiber epoxy composite, structure will be low weight, satisfy 1st bending natural frequency and have high fatigue resistance. In this study, research on to manufacture hybrid propeller-shaft using carbon fiber epoxy composite instead of current steel propeller shaft of rear wheel drive vehicle. For this, change of 1st bending natural frequency by the number of layers of carbon fiber epoxy composite on the outer surface of aluminum shaft was observed. Compared the change of 1st bending natural frequency by FEA with computer simulation and vibration test. Through this, the amount of increase in 1st bending natural frequency of hybrid shaft by the increase in number of layers of carbon fiber epoxy composite and high vibration characteristics of hybrid shaft was acknowledged.