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탄소강의 담금질 처리과정에서 변형율이력을 고려한 탄소성열응력의 유한요소 해석(1) - 온도분포의 해석 -
김옥삼,조의일,구본권 ( Ok Sam Kim,Eui Il Cho,Bon Kwon Koo ) 한국열처리공학회 1995 熱處理工學會誌 Vol.8 No.3
Temperature distribution, transformation and residual stresses generated during the quenching process of carbon steel. It follows many difficulties in the analytical considerations on those quenching process because of the coupling effects on temperature and metallic structures. In this paper one of the basic study on the quenching stresses was carried out for the case of the round steel bar specimen(SM45C) with 40㎜ both in its diameter and length. The temperature distributions considering strain hysteresis were numerically calculated by finite element technique. In calculating the transient temperature field, the heat flux between water and rod surface was determined from the heat transfer coefficient. The gradient of temperature is almost same to geometric of specimen. At early stage of the quenching process, the abrupt temperature gradient has been shown in the surface of the specimen.
승용차용 미소가속도 센서 축전기부의 전기적성질에 관한 유한요소 해석
김옥삼 여수대학교 1998 論文集 Vol.12 No.2
The microaccelerometer for passenger car using a tunnelling current concept has the potential of high performance, although it requires slightly complex signalprocessing circuit for servo-system. The paddle of microaccelerometer is pulled to have the gap width of about 2nm which almost allows the flow tunnelling current. In the analysis the capacitor volume of microaccelerometer is divided into 22 rectangular (4-node) element. This paper demonstrates at capacitor the use of the coupled the thermo-electric analysis for voltage, current, heat flux and Joule heating then tunnelling current flows. Two electrodes are applied to the microaccelerometer producing a unform difference of temperature gradient and electric potential between the paddle and the substrate.
김옥삼,박우철,구본권 韓國工作機械學會 2000 한국생산제조학회지 Vol.9 No.3
The object of this research is to estimate for pearlite structure of quenched carbon steels. The effects of temperature on physical properties, metallic structures and the latent heat by phase transformation were considered. In this study a set of constitutive equations relevant to the analysis of thermo-elasto plastic materials with pearlite phase transformation during quenching process way presented on the basis of continuum thermo-dynamics. The iso-thermal transformation curve of the SM50C was formulated by cubic spline curve. The formulated equations of evolution in pearlite transformation was used for structure analysis. The volume fraction of pearlite was obtained from the results of calculated metallic structures by Finite element equation.
김옥삼 전남대학교 수산과학연구소 2012 수산과학연구소논문집 Vol.20 No.-
For a more thorough understanding of the influence of micro and macro organisms on sea water, a study of the voluminous literature on the subject is recommended. While some researchers contend that the effect of microbial buried in the sea water, others believe that in many cases, if not most the effect of bacillariaceae is nominal. In one such study it is contended that a principal reason for corrosion of sea water is difference in oxygen availability which results in long cell action. In this paper it is contented that pH has essentially no effect on corrosion over the range from 5 to 9, in which most sea water.
김옥삼 麗水大學校 産業基術硏究所 1999 産業基術硏究所 論文集 Vol.8 No.-
The major advantage in using power cylinder system for industrial car is that large output power can be quickly controlled by very small power level signals. Valve controlled power cylinder system servo drives are an interal part of dump truck, aircraft flap, wing surface engine, landing-gear control, controls for steel mills and other heavy industrial equipments. Although power cylinder system of sump trucks do provide a good understanding of the relative effects of the various control parameters on dynamic performance, detailed system design must include consideration of the inherent nonlinearities to assure a good understanding of large signal response and stability.
선박용 TEMA 열교환기의 전열관 확관시 탄소성 응력 해석
김옥삼,박종대,Kim, Ok-Sam,Park, Jong-Dai 해양환경안전학회 2011 해양환경안전학회지 Vol.17 No.2
선박에 사용되는 TEMA 열교환기 전열관의 확관 공정에서 발생되는 탄소성 응력과 변형량의 거동을 유한요소법으로 해석하였다. 열교환기의 관판 구명의 홈 깊이와 롤러 익스팬더의 작용압력을 변화시켜 해석한 결과, 전열관의 관판 구멍의 홈 깊이가 커지면 탄소성 압축응력은 감소하였고, 롤러 익스팬더 압력이 높을수록 관판 구멍의 홈 모서리 부분의 탄소성 응력이 증가되었다. Marine TEMA heat exchanger is the equipment to transfer the heat energy through both fluids that are enclosed separately by applying conduction and convection phenomena for a large vessels, Especially for heat exchanger working under the high temperature and high pressure, the expansion ratio should be taken into account other than under the low temperature and low pressure. This study was tried to find out the ideal expansion ratio through analyzing the elasto-plastic stress behavior of deformation while tubes are expanded with the finite element methods.
Quenching과정에서 상변태를 고려한 탄소성 열응력의 유한요소 해석 (2) - 오오스테나이트에서 마르텐사이트로의 변태 -
김옥삼,송관흠,구본권 ( O . S . Kim,G . H . Song,B . K . Koo ) 한국열처리공학회 1995 熱處理工學會誌 Vol.8 No.1
In this a set of constitutive equation relevant to the analysis of thermo-elasto-plastic materials with phase transformation during quenching process was presented on the basis of continuum thermodynamic. In calculating the transient thermal stresses, temperature between coolant and specimen(SM45C) surface was determined from the heat transfer coefficient. A calculation was made for specimen with 40㎜ in diameter quenched in coolant from 820℃ and the results are as follow. Stresses at starting point of transformation always show the maximum tensile value. Reverse of stresses takes place after completion of transformation of inner part at specimen.
Quenching과정에서 상변태를 고려한 탄소성 열으역의 유한요소해석(1) - 오스테나이트에서 퍼얼라이트의 변태 -
김옥삼,구본권 ( Ok Sam Kim,Bon Kwon Koo ) 한국열처리공학회 1994 熱處理工學會誌 Vol.7 No.4
Constitutive relation of thermoelasto-plastic material undergoing phase transformation during quenching process were developed on the basic of continuum thermodynamics. The metallic structure, temperature and residual stresses distributions were numerically calculated by the finite element technique. The metallic structure were defined by transformation from austenite to pearlite and characterized as a fuction of thermal history and mixture rule of phase. On the distribution of thermal stress along the radial direction, axial and tangential stresses are compressive in the surface, and tential in the inner part. Radial stress is tensile in the whole body. The reversion of residual stress takes plase at 11.5∼15.5㎜ from the center.
Quenching시 나트륨계 수용액의 냉각성능에 관한 연구
김옥삼,최은순,민수홍 ( Ok Sam Kim,Eun Soon Choi,Soo Hong Min ) 한국열처리공학회 1992 熱處理工學會誌 Vol.5 No.4
Coolingability of coolants is important factor in cooling processor heat treatment of steel, Using standard apparatus and method defined in the Korean Industrial Standard three different shapes of probe were designed, ie, cylinderical, spherical and square on shape with same volume of standard probe. Distilled water and sodium aquious solutions with different concentration of NaOH, NaCl and Na₂CO₃were examined. Estimation of coolingability of each quenchants for the probes of cylinderical, spherical or square shape, the cooling rate is greater square, cylinder and sphere in order. Coolingability of sodium aquious solution of NaCl, Na₂CO₃and NaOH is found generally greater then that of distilled water. Effectiveness of ingredients is in the order of Na₂CO₃, NaOH and NaCl. In both solutions coolingability increases in 20%, 5%, and 10% in order. Analytical results obtained from Finite Element Method were compared with experimental ones and found as practically satisfactional.