http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
신효철 대한기계학회 1991 대한기계학회논문집 Vol.15 No.6
본 연구에서는 재료 결정격자의 기본단위나 결정립의 형상등 가장 기본적인 형태가 6각형이라는 점에 착안하여 취성재료의 파손모델로 부재들의 결손을 이용하는 결손확률모델을 제안하여 부재결손에 따른 각각의 파손 해석모델과 결손확률을 구한다. 그리고 비결손모델에서 구한 기본인장하중을 기초로 하여 해석하고자 하는 하중하에서 각각의 파손해석모델을 모델링하여 유한요소법으로 부재결손에 따른 요소중심에서의 최대주응력을 구하여 이론극한인장강도와의 비와 결손확률로 취성재료의 파손확률을 구한다. 또한 취성정도에 따른 균열길이에 대한 치수 매개변수를 구함으로써 재료강 도 연구에 기초가 되게 한다. Strength is not simply a single given value but rather is a statistical one with certain distribution functions. This is because it is affected by many unknown factors such as size, shape, stress distribution, and combined stresses. In this study, a model of loss probability is proposed in view of the fact that one of the fundamental configuration of nature is hexagonal, for example, the shapes of lattice unit, grain, and so on. The model sues the concept of loss of certain element in place of Jayatilaka-Trustrum's length and angle of cracks. Using this model, the loss probability due to each loss of certain elements is obtained. Then, the maximum principal stress is calculated by the finite element method at the centroid of the elements under the tensile load for the 4,095 models of analysis. Finally, the failure probability of the brittle materials is obtained by multiplying the loss probability by the ratio of the maximum principal stress to theoretical tensile strength. Comparison of the result of the Jayatilaka-Trustrum's model and the proposed model shows that the failure probabilities by the two methods are in good agreement. Further, it is shown that the parametric relationship of semi-crack lengths for various degrees of birittleness can be determined. Therefore, the analysis of the failure probability suing the proposed model is shown to be promising as a new method for the study of the failure probability of birttle materials.
呂東吉,申孝哲 啓明大學校 産業經營硏究所 1983 經營經濟 Vol.16 No.1
Fundamentally, it is impossible for an investor to expect perfect optimization of decision making under uncertainty, But ultimately it is possible for an investor to pursue optimization based on limited rationality. From those assumptions we can induce following conclusion. Marbowitz Model enabled it possible to establish portfolio indicating optimum leturn-risk level in efficient frontier. Standard deviation is the best means of measuring the risk on stock and portfolio. Sharp Model classified the risk of securities into systematic risk and unsystematic risk. Unsystematic risk can be reducced to Zero by means of appropriate variations, but on the contrary, systematic risk (β coefficient) cannot be reduced perfectly. Lintner Model explained the equity theory of capital market premising dominance principle, homogenious expectations or predictions of an investor, and perfect capital market. Farra Model showed the choice standard of the best portfolio in efficient portfolio. In securities investment decision, it is not the inter-relation between expected return and risk of security, but the interrelation (coveriance) of portfolio securities. Therefore, diversifiable securities are preferable to investors. Efficient Portfolio combination bas small variance in the same level expectation or has high expectation in the same variance. level A reasonable investor can decide the best portfolio by means of an indifference curve.
신효철(Hyo-Chul Shin),신민호(Min-Ho Shin),조국환(Kook-Hwan Cho) 한국철도학회 2013 한국철도학회 학술발표대회논문집 Vol.2013 No.11
터널굴착 시 단층파쇄대와 같이 불량한 암반이 존재할 경우 터널보강 및 시공에 많은 어려움이 있고, 이에 따른 보강, 보조공법이 나날이 발전되어가고는 있지만 아직까지 여러가지 이유로 인해 공사 중 붕괴 사고가 종종 발생되고 있다. 본 논문은 철도터널 시공 중 파쇄대 지역의 붕락 중 측벽부 붕락에 대하여 설계 적용된 일반 물성치하에서 존재된 파쇄대 방향 변화가 터널붕락 유형과 어떠한 상관성이 있는지, 실제 발생한 파쇄대 방향 49도 일 때 붕괴양상의 검정을 통하여, 30도 45도 60도 75도 일 때 파쇄대 방향변화를 통하여 터널의 파괴 유형을 도출하였다. 연구결과, 파쇄대 각도와 파괴영역과의 상관관계, 최대 파괴 깊이 및 방향을 제시하였으며 연구결과를 바탕으로 파쇄대의 존재에 따른 대책수립이 가능할 것으로 판단된다. If there is a fracture zone such as poor rock tunneling, many difficulties were encountered in the tunnel reinforcement and construction. Thus, reinforced and sub method of construction is continuously developed. But, collapse accidents during construction still are often occured by various reasons. In this paper, Assuming the direction of the fracture zone change and side wall of tunnel collapse type, the destruction types of the tunnel are derived through the verification of collapse patterns when incurred direction of the fracture zone is 49 degrees, 30 degrees, 45 degrees, 60 degrees, 75 degrees each other. As a result, there is suggested that a relationship between the fracture angle and zone, the maximum fracture depth and direction. According to this study, it is expected that measures to establish from the existence of fracture zone.
신효철 ( Hyo Chul Shin ),김규용 ( Gyu Yong Kim ),김정현 ( Jung Hyun Kim ),김진만 ( Jin Man Kim ) 한국건축시공학회 2015 한국건축시공학회 학술발표대회 논문집 Vol.15 No.2
In this study, fresh state properties and mechanical properties of low slump concrete which is applied to road pavement have been evaluated by mixing modified sulfur. As results, influence of mixing modified sulfur on the workability was low. Also, compressive strength, and flexural strength tend to decrese with increasing addition rate of modified sulfur. However compressive strength, and flexural strength of modified sulfur concrete were equivalent with that of plain concrete.
이호상,신효철 대한기계학회 1992 대한기계학회논문집 Vol.16 No.7
본 연구에서는 IBPR 방법을 바탕으로 캐비티형상이 동일평면상에 있지 않은 경우에 대한 준3차원 유동해석과 주입기구가 있는 경우에 대한 유동해석을 별도로 수 행하여 실험결과와 비교하였다.해석결과는 실험과 잘 일치하였으며 그를 통해 앞서 개발한 IBRP방법이 보다 일반적인 경우에서의 캐비티 유동해석으로 확장, 응용될 수 있음을 확인할 수 있었다. In order to determine the design parameters and processing conditions in injection molding, it is very important to establish the theoretical model with scientific base. In this study, a two dimensional model has been developed for the purpose and flow simulations of filling process are carried out. The moving boundary transient flow problem along the flat plane is solved efficiently by the Iterative Boundary Pressure Reflection Method which rearranges the impinged melt front along the physical boundary in scientific manner. The two dimensional modeling of filling process is applied to two examples : a three dimensional cover with two screw holes and a two-gated flat cavity with unbalanced runners. The numerical results show good agreement with experimental short shots, especially for the weldline locations and the pressure traces at various locations. They also provide the temperature, clamp force, and velocity field in the mold at different times during filling of cavity.