• Journal of Mechanical Science and Technology
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• 제18권2호
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• pp.253-261
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• 2004

A simple and effective filtering method to control the member size of an optimized structure is proposed for topology optimization. In the present approach, the original objective sensitivities are replaced with their relative values evaluated within a filtering area. By adjusting the size of the filtering area, the member size of an optimized structure or the level of its topological complexity can be controlled even within a given finite element mesh. In contrast to the checkerboard-free filter, the present filter focuses on high-frequency components of the sensitivities. Since the present filtering method does not add a penalty term to the objective function nor require additional constraints, it is not only efficient but also simple to implement. Mean compliance minimization and eigenfrequency maximization problems are considered to verify the effectiveness of the present approach.

• Earthquakes and Structures
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• 제2권3호
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• pp.279-295
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• 2011

This paper develops a probabilistic methodology for the seismic reliability analysis of structures with random properties. The earthquake loading is assumed to be described in terms of response spectra. The proposed methodology takes advantage of the response spectra and thus does not require explicit dynamic analysis of the actual structure. Uncertainties in the structural properties (e.g. member cross-sections, modulus of elasticity, member strengths, mass and damping) as well as in the seismic load (due to uncertainty associated with the earthquake load specification) are considered. The structural reliability is estimated by determining the failure probability or the reliability index associated with a performance function that defines safe and unsafe domains. The structural failure is estimated using a performance function that evaluates whether the maximum displacement has been exceeded. Numerical illustrations of reliability analysis of elastic and elastic-plastic single-story frame structures are presented first. The extension of the proposed method to elastic multi-degree-of-freedom uncertain structures is also studied and a solved example is provided.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.397-402
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• 2007

Application of hydroforming technology for Engine Cradle has done much to reduce the weight of it. In most cases, hydroformed member of Engine Cradle is made in one-piece. And this method cause a limeted design that amount of expansion at the center portion of the member is not enough to meet the required performance. This limited design leads to decrease the dynamic characteristics of Engine Cradle. In this paper, comparative analyses of conventional stamped engine cradle and hydroformed cradle of one-piece were conducted using Normal Mode analysis and FRF(Frequancy Response Function)analysis. Finally, to improve the disadvantage mentioned above, hydroformed member of 3-pieces was proposed.

• 디지털콘텐츠학회 논문지
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• 제3권1호
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• pp.123-130
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• 2002

본 mailing list system은 데이터 베이스 접근 시 데이터 베이스 ODBC설정정보를 따로 저장하지 않고 mailing list 만을 목적으로 E-mail만 발송하기 때문에 데이터베이스의 무단사용을 막게 되어 있으며, 홈페이지의 회원으로 가입한 가입자의 신상 중 E-mail 주소를 데이터 베이스로부터 읽어들여 전체 또는 어느 특정 층에 해당하는 사람들에게 E-mail을 보낸다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2002년도 가을 학술발표회 논문집
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• pp.287-294
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• 2002

An automatic design method of steel frames using nonlinear analysis is developed. The geometric nonlinearity is considered by the use of stability functions. A direct search method is used as an automatic design technique. The unit value of each member is evaluated by using LRFD Interaction equation. The member with the largest unit value Is replaced one by one with an adjacent larger member selected in the database. The weight of the steel frame is taken as an objective function. Load-carrying capacities, deflections, interstory drifts, and ductility requirement are used as constraint functions. Case study of a three-dimensional two story frame are presented.

• 대한가정학회지
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• 제49권5호
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• pp.97-115
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• 2011

The focus of this study was on the self-differentiation level of families with an elderly member suffering from dementia. Based on 340 questionnaires collected in Seoul and Gyeonggi, the study intended to explain the adaptation issues of those families. The variables of interest, which might be related to the self-differentiation, were chronic anxiety(i.e. stress), the family function, psychosomatic symptoms and the family's adaptation to care-giving. As a result of analyzing the effects of the variables potentially related to the self-differentiation level of care-giving families, the findings from this study were as follow. With decreasing self-differentiation level of the family caring for an elderly member suffering from dementia, the levels of stress and psychosomatic symptoms were significantly increased, but the family function and the adaptation to care-giving tended to decrease. Conversely, with increasing self-differentiation, the levels of stress and psychosomatic symptoms were significantly decreased, while the family function and adaptation to care-giving were promoted.

• 대한기계학회논문집
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• 제14권5호
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• pp.1069-1078
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• 1990

본 연구에서는 평면응력 및 평면변형률 문제의 유한요소법해석에 있어서 기존 의 면적좌표를 이용한 삼각형요소나 4절점 isoparametric 사변형요소보다도 정확도가 높은 에너지 직교함수(energy orthogonal function)에 의한 사변형요소를 개발하고 이 유한요소 프로그램을 이용하여 사각형 부재내의 집중하중과 분포하중에 의한 응력집중 현상과 소멸현상을 고찰하는데 있다.

• Steel and Composite Structures
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• 제29권5호
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• pp.623-633
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• 2018

A robust element is essential for successful design of steel frames with Direct analysis (DA) method. To this end, an innovative and efficient curved-quartic-function (CQF) beam-column element using the fourth-order polynomial shape function with end-springs in series is proposed for practical applications of DA. The member initial imperfection is explicitly integrated into the element formulation, and, therefore, the P-${\delta}$ effect can be directly captured in the analysis. The series of zero-length springs are placed at the element ends to model the effects of semi-rigid joints and material yielding. One-element-per-member model is adopted for design bringing considerable savings in computer expense. The incremental secant stiffness method allowing for large deflections is used to describe the kinematic motion. Finally, several problems are studied in this paper for examining and validating the accuracy of the present formulations. The proposed element is believed to make DA simpler to use than existing elements, which is essential for its successful and widespread adoption by engineers.

• 한국공간구조학회논문집
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• 제3권2호
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• pp.85-90
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• 2003

If we use a third order approximation for the displacement function of beam element in finite element methods, finite element solutions of beams yield nodal displacement values matching to beam theory results to have no connection with the number increasing of elements of beams. It is assumed that, as the member displacement value at beam nodes are correct, the calculation procedure of beam element stiffness matrix have no numerical errors. A the member forces are calculated by the equations of $\frac{-M}{EI}=\frac{{d^2}{\omega}}{dx^2}\;and\;\frac{dM}{dx}=V$, the member forces at nodes of beams have errors in a moment and a shear magnitudes in the case of smaller number of element. The nodal displacement value of plate subject to the lateral load converge to the exact values according to the increase of the number of the element. So it is assumed that the procedures of plate element stiffness matrix calculations has a error in the fundamental assumptions. The beam methods for the high accuracy ratio solution Is also applied to the plate analysis. The method of reducing a error ratio of member forces and element stiffness matrix in the finite element methods is studied. Results of study were as follows. 1. The matrixes of EI[B] and [K] in the equations of M(x)=EI[B]{q} and M(x) = [K]{q}+{Q} of beams are same. 2. The equations of $\frac{-M}{EI}=\frac{{d^2}{\omega}}{dx^2}\;and\;\frac{dM}{dx}=V$ for the member forces have a error ratio in a finite element method of uniformly loaded structures, so equilibrium node loads {Q} must be substituted in the equation of member forces as the numerical examples of this paper revealed.

• 미생물과산업
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• 제16권3호
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• pp.6-14
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• 1990

PRDI DNA polymerase is the smallest member of the family B DNA polymerase (Jung et al., 1987). This DNA polyerase is specified by bacteriophage PRDI which infects a wide variety of gram-negative bacteria(Mindich and Bamford, 1988). Because PRDI is highly amenable to genetic and biochemical manipulation, it is a convenient model system with which to study structure-function relationships of DNA polymerase molecules. To determine the functional roles of the highly conserved regions of the family B DNA polymerases, we have initiated site-directed mutagenesis with PRD1 DNA polymerase, and our results show that mutations at the conserved regions within PRD1 DNA polymerase inactivate polymerase complementing activity and catalytic activity.