AISI 4340 ?? 鋼의 衝擊에너지와 ??값 사이의 相互關係에 관한 硏究

성낙원,심봉식 東亞大學校 大學院 1986 大學院論文集 Vol.11 No.-

Charpy V-notch impact test and compact tension test in the enviroment of high and low temperature on the specimens of N?C?M? steel have been conducted. This paper is to evaluate the correlation between CVN and K? test results as a function of temprature. The results of this study are as follows. 1. The transition temperature by the effect of impact absorption energy from lower shelf to upper shelf have the tendencies of increasing with the incrase of temperature. 2. The value of K? measired from compact test is linearly increased with the increase of temperature. 3. The empirical correlation between impact energy and value of K? is obtained as K?/E=3.2545(CVN)-5.0064 and the rates of the erro from the test results are within 7pe cent.

공업고등학교에서 전자의 기초 이론 학습을 위한 WBI 개발 및 그 학습효과에 관한 연구

최완식,박락영 충남대학교 공업교육연구소 1999 論文集 Vol.22 No.1

The major purposes of this study were: (a) to develop a WBI on the basic teaming of 'electron', (b) to determine if learning effect with the WBI is better than the learning effect with the traditional instruction, (c) to identify whether there is different learning effect between the WBI group with left-menu and the group with right-menu, and (d) to identify whether the students who had learned the lesson(electron subject in the technical high school) with the WBI show better learning attitude on the lesson than the students with the traditional instruction do. Followings were the major findings of this study. (1) The students who had teamed the lesson with WBI showed statistically higher learning abilities of the lesson than the students teamed through the traditional method did. (2) In the WBI experimental groups, the scores obtained just after the lesson had no difference between the WBI group with right-menu and the WBI group with left-menu, but the scores obtained after one week were statistically higher in the WBI group with right-menu than the group with left-meun. (3) In a sense of an average score of the attitude, the students who had learned the lesson with WBI had higher attitude scores than the students learned through the traditional method had. (4) In the WBI experimental groups, there was no difference in the learning attitudes between left-menu group and the right-menu group.

ESO 기법을 이용한 신뢰성 기반 최적설계

김상락,박재용,이원구,유진식,한석영 한국공작기계학회 2007 한국공작기계학회 추계학술대회논문집 Vol.2007 No.-

This paper presents a Reliability-Based Topology Optimization (RBTO) using Evolutionary Structural Optimization (ESO). An actual design involves uncertain conditions such as material property, operational load and dimensional variation. Deterministic Topology Optimization (DTO) is obtained without considering of uncertainties related to the uncertainty parameters. However, RBTO involves evaluation of probabilistic constraints, which can be done in two different ways, the reliability index approach (RIA) and the performance measure approach (PMA). Limit state function is approximated using Monte Carlo Simulation and Central Composite Design for reliability analysis. ESO, one of the topology optimization techniques, is adopted for topology optimization. Numerical examples are presented to compare the DTO with RBTO.

흡연자에서 내피세포 의존성 혈관이완 반응과 비타미 C의 단기효과

최락경,고충원,임달수,황흥곤 世宗醫學硏究所 2000 世宗醫學 Vol.17 No.2

AISI 4340鋼의 引張特性 및 破壞靭性에 미치는 溫度의 影響에 관한 硏究

성낙원,심봉식 동아대학교 공과대학 부설 한국자원개발연구소 1991 硏究報告 Vol.15 No.1

The K_(IC) value derived from CVN test were considerably different from measured value and it was difficult to predict the correct K_(IC) value of the materials under consideration. Compact tension and Charpy V―notch test in the invironment of high and low temperature on the specimen of AISI4340 steel have been conducted. The results may be sumerized as follows. The transition temperature by the impact absorbation energy range from - 50℃ and 150℃ and the impact energy from lower and high shelf have a tendencies of increasing with increase of the temperature. The measured K_(IC) value from CT test linearly increased with the increase of temperature. The K_(IC) value from the test fomular were derived and the error are within 6.8% against measured K_(IC) value.

축방향의 압축하중을 받는 얇은 원통 "쉘"의 좌굴에 관한 실험적 연구

成洛元 東亞大學校 大學院 1981 大學院論文集 Vol.5 No.-

An experimental study of the buckling of thin cylindrical shell under the axial compression was carried out. Buckling procedure were obserbed and the results obtained for the buckling stress were compared with theoretical value and approximate soulution of the exisiting literature. The test model of aluminum alloy were used. From this study, the results are as follows; Buckling behavior is a dynamic procedure combinded with potential change due to the bending energy stored by the successive compression load. The pattern of buckling wave formed in rhombic figure and the length of these wave in axial direction and circumferential direction were same. Buckling of thin cylindrical shell occured in the limit of elasticity and buckling load were less the theoretical balue. The results obtained were good agreement with the approximate solution and emperical formula for the buckling load be induced in the form

ESO 기법을 이용한 컴플라이언트 메커니즘 설계

이원구,박재용,김상락,유진식,한석영 한국공작기계학회 2008 한국공작기계학회 춘계학술대회논문집 Vol.2008 No.-

A compliant mechanism is a mechanism that produces its motion by the flexibility of some or all of its members when the input forces are applied. Whereas the topology optimization based on homogenization and SIMP parameterization has been successfully applied for compliant mechanism design, an ESO approach has not been considered yet for the optimization of these types of systems. This work presents a modified version of the evolutionary structural optimization (ESO) Procedure for its application in topology optimization of compliant mechanisms, It will be shown that an additive version of this method must be adopted in order to achieve the optimum design, since the traditional ESO method's element removal technique is not efficient in this case. The methodology is based on a mutual energy concept for formulation of flexibility and the ESO method. A multi-objective optimization problem is formulated as an application of compliant mechanism design. The procedure has tested in several numerical applications and benchmark examples to illustrate and validate the approach.

複合組織鋼의 低 및 高 사이클 疲勞特性에 관한 硏究(Ⅱ) : 高사이클 疲勞特性

成洛元 東亞大學校 大學院 1988 大學院論文集 Vol.13 No.-

In this study, a series of experiments on the dual phase steel with different grain size are performed to investigate high cycle fatigue properties. Specimen of SM 20C steel, matrix material and the dual phase steel consisting of three different sized grains were subjected to a series of high cycle fatigue test. The crack propagation rate in the high cycle fatigue region also has been examined taking in to consideration of crack closure effect. The test results in high cycle region show that the propagation rate in most range of stable crack propagation, second stage, are linealy aranged by using the effective stress intensity factor range. Dual phase steel are superior to SM 20C steel in fatigue limit and has longer fatigue life. The ratio of fatigue propagation life and fatigue limit are decreased as it approches to the value of fatigue limit. The aspect ratio of the surface crack length and the depth show constant slope between 0.68 and 0.78. The curve of U, the ratio of effective stress intensity factor range versus crack length show an asymptote to the constant value as the crack length increase. Through above mentioned experimental results, it is also found that the crack propagation rate is quite dependent to the crack length and stress amplitude in the local range. And fatigue life of the dual phase steel in the region of stable crack propagation could be predicted in term of effective stress intensity factor range.

다단변동/충격하중하의 탄소섬유강화 복합재료의 피로강도 특성 및 잔류강도 저하거동에 관한 연구

성낙원,이수진 동아대학교 공과대학부설 생산기술연구소 1996 生産技術硏究所硏究論文集 Vol.1 No.-

Under the multi-step loading and impact loading, similar to real loading, fatigue tests have been carried out to examine the characteristics of a fatigue strength and a fatigue life and the degradation of the residual strength in carbon-epoxy composite materials. Two different shape of test specimen and test methods were used and the theory of cumulative damage and the residual strength degradation was applied to the test data of two parameter Weibull distribution. The static ultimate strength of the test piece used here in is observed to be relatively higher than that of existing composite materials, while fatigue life is shorter than that of estimated by residual strength degradation model when the stress level above 0.62. The fatigue life of the materials tested were observed the one of the high-low multi-step was longest and the one of the low-high next compared by Miner's value. It is proven that the prediction of fatigue life by the analysis of the theory of cumulative damage and degradation is resonable.

炭素纖維强化 複合材料의 機械的 强度特性 및 疲勞壽命豫測에 관한 硏究

成洛元,沈奉植 동아대학교 공과대학 부설 한국자원개발연구소 1993 硏究報告 Vol.17 No.1

An experimental investigation was performed on the carbon-epoxy resin composite materials under constant stress amplitude and two step loading high low type and low high type loading, to study the mechanical properties and fatigue properties. Different shape of test specimen and test methods were used for evaluating the dispersion pattern in fatigue life and its reliability. A statistical approach was applied to test data with the aid of two parameter Weibull probabilities. It is indicated that the dispersions in the fatigue life are more wider at the high stress amplitude than at the low stress level and fatigue life was extended in the two step loading. Experimental data for the fatigue life showed good agreement with the one of the theoretically predicted at high stress level.