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In situ 중합으로 제조된 nylon 6-PEO copolymer/MMT 나노복합체의 물성연구
김택현,이종순,김갑진,Kim Taeck Hyun,Lee Jong Soon,Kim Kap Jin 한국섬유공학회 2004 한국섬유공학회지 Vol.41 No.6
To improve the impact strength of nylon 6 at low temperature, poly(ethylene oxide) unit was incorporated into nylon 6 main chain. This method, however, was accompanied with some unavoidable problems such as the drastic decrease in modulus and breaking strength and highly increased elongation at break. To resolve these problems, we obtained the nylon 6-PEO copolymer/montmorillonite nanocomposites chips from thein situ polymerization of $\varepsilon-caprolactam$ in the presence of 12-aminododecanoic acid intercalated montmorillonite using poly(ethylene oxide) diamine as a soft segment and 6-aminocaproic acid as a polymerization catalyst. Their structural, thermal, and mechanical properties were characterized using wide angle x-ray diffraction(WAXD), SEM, DSC, and tensile testing.
구조용강 용접재의 피로크랙 전파거동에 미치는 용접후 열처리의 영향
김택현 조선대학교 동력자원연구소 1993 動力資源硏究所誌 Vol.15 No.1
The weld structures, residual stresses to be induced by welding operation are primary factors which influence on the fatigue crack growth rate. Therefore, in this paper, after the Structural steels are welded by Submerged Arc, were investigated the effect of residual stresses and post welded heat treatment on the fatigue crack growth behavior. The main conclusions are as follows; 1. The initial cracks of PWHT(Post Weld Heat Treatment)at the top of slit are more a few quickly generated then the welding materials, but the fatigue crack propagation rate in the whole of life-time is slow. 2. The softening phenomenon of heat treatment doesn't bring large effect to the welding materials and hardness distribution of TWHT, but it brings the large effect of stress retardation rate on initial crack propagation steps. 3. While the distribution of initial residual stresses at crack tip are measured, fatigue crack propagation behavior of weldments consisted with the base metal.
복합재료 적층판의 유한요소 해석을 위한 효율적 경계조건
김택현,김인권 한국공작기계학회 1998 한국생산제조학회지 Vol.7 No.3
This paper presents three boundary techniques which are useful for FEM analysis of composite laminates : 1) a rotational symmetric boundary technique. 2) a quasi three-dimensional boundary technique and 3) a contact boundary technique. The use of the rotational symmetric boundary technique is possible for a smaller FEM model. With the use of the quasi three-dimensional boundary technique. quasi three-dimensional analysis of composite laminates can be performed on the conventional 3-D FEM program. These techniques can readily be adopted to FEM programs.
비대칭 보에 의해 보강된 등방성 평판의 음향방상에 관한 연구
김택현,오택열,김종태,Kim, Taek-Hyun,Oh, Taek-Yul,Kim, Jong-Tye 대한기계학회 1998 大韓機械學會論文集A Vol.22 No.4
The determination of sound pressure radiated from periodic plate structures is fundamental in the estimation of noise level in aircraft fuselages or ship hull structures. As a robust approach to this problem, here a very general and comprehensive analytical model is developed for predicting the sound radiated by a vibrating plate stiffened by periodically spaced orthogonal unsymmetrical beams subjected to a sinusoidally time varying point load. The plate is assumed to be infinite in extent, and the beams are considered to exert both line force and moment reactions on it. Using this theoretical model, the sound pressure levels on axis in a semi-infinited fluid (water) bounded by the plate were calculated using three numerical tools such as the Gauss-Jordan method, the LU decomposition method and the IMSL numberial package. Especially, the variation in the sound pressure levels and their modes were investigated according to the change in frequency, bay spacing and bay distance.
金澤鉉,梁仁榮 조선대학교 동력자원연구소 1983 動力資源硏究所誌 Vol.5 No.1
Surface-hardening shafts are using very much in order to satisfy the limit condition of the deformation. Thus, in this study we considered torsion characteristic from high-freguency heat treatment on the SM45C steel. We investigate the possibility of deriving stress-strain information from the torgue-twist data available from experiments. The obtained results are summarized as follows; 1) Shearing strains at the break point and the yielding point were remarkeably improved for surface hardening shafts. 2) The initial crack occurred at ※ point because of the stress concentration and the formation of surface hardening layer at the corner of key way as shown in Fig.2. 3) The structures of non-treatment materials were unstable since torsional angle has been got ten degrees.