• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 춘계학술대회 논문집
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• pp.272-275
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• 2007

This paper is concerned with modified integration algorithm on the strain-space for rate and temperature dependent elasto-plastic constitutive relations in order to obtain more accurate results in numerical implementation. The proposed algorithm is integrated analytically using integration by part and chain rule and then is applied to the 2-stage Lobatto IIIA with second-order accuracy. It has advantage that is able to consider the convective stress rates on the yield surface of the strain-space. Also this paper is carried out the iteration procedure using the Newton-Raphson method to enforce consistency at the end of the step. And the performance of the proposed algorithm for rate and temperature dependent constitutive relation is illustrated by means of analysis of adiabatic shear bands.

• 대한전자공학회논문지
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• 제24권4호
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• pp.559-567
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• 1987

In this paper, the real time simulation of continuous dynamic system was performed by general integration algorithms using multiprocessor. For the stable simulation, the relation between stability of integration method and integration step-size was investigated from the stability graph. As a typical illustration, the real-time digital simulation and the real-time hard-ware-in-the-loop simulation of flight control system were performed and reviewed. Moreover through the real-time simulation, the design verification and performace test of flight control system could be evaluated. The computer used for simulation is AD10, which is a very high-speed special-purpose computer designed specifically for a time-critical simulation of large and complex models of dynamic systems. The simulation validity is demonstrated by comparing hardware simulation results with software simulation results.

• International Journal of CAD/CAM
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• 제9권1호
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• pp.17-24
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• 2010

For several years, researchers have focused on improving the integration of the CAD, CAM and Analysis through a better communication between the various analysis tools. This tendency to integrate the CAD/Analysis and automation of the corresponding processes requires data sharing between the various tasks using an integrated product model. We are interested in this research orientation to CAD/CAM/Analysis integration by rebuilding the CAD model (BREP), starting from the Analysis results (deformed mesh). Because this problem is complex, it requires to be split into several complementary parts. This paper presents an original interoperability process between the CAD and CAE. This approach is based on a new technique of rebuilding the CAD surface model (Nurbs, Bezier, etc.) starting from triangulation (meshed surface) as a main step of the BREP solid model. In our work, the advantages of this approach are identified using a centrifugal pump example.

• 한국군사과학기술학회지
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• 제13권1호
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• pp.50-56
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• 2010

Military technology transition is the process of transition from the science and technology environment to systems to supply effective weapon systems and support systems to the fighters. In case of technology transition decision, immatured technologies result in increasing acquisition cost and delaying schedule toward the objective system. In this paper, we proposed a method to identify and select critical technology elements by integration relations between technologies or components, for supporting technology transition and risk management of military R&D projects.

• Journal of Ship and Ocean Technology
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• 제9권3호
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• pp.33-42
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• 2005

As the networks connect the world, enterprises tend to move manufacturing activities into virtual spaces. Since different software applications use different data terminology, it becomes a problem to interoperate, interchange, and manage electronic data among heterogeneous systems. It is said that approximately one billion dollar has been being spent yearly in USA for product data exchange and interoperability. As commercial CAD systems have brought in the concept of design feature for the sake of interoperability, terminologies of design features need to be harmonized. In order to define design feature terminology for integration, knowledge about feature definitions of different CAD systems should be considered. STEP standard have attempted to solve this problem, but it defines only syntactic data representation so that semantic data integration is not possible. This paper proposes a methodology for integrating modeling features of CAD systems. We utilize the ontology concept to build a data model of design features which can be a semantic standard of feature definitions of CAD systems. Using feature ontology, we implement an integrated virtual database and a simple system which searches and edits design features in a semantic way.

• 한국노년학
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• 제41권4호
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• pp.491-504
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• 2021

본 연구는 노인의 죽음불안이 자아통합감에 미치는 영향을 알아보고, 죽음불안과 자아통합감의 관계에서 심리적 안녕감의 매개효과를 검증하였다. 이를 위해 서울 및 경기 지역 노인 관련 시설에 거주하는 65세부터 94세까지의 노인 254명을 대상으로 2020년 9월 1일부터 같은 해 11월 30일까지 설문을 시행하였고, 측정도구로는 죽음불안 척도, 심리적 안녕감 척도, 자아통합감 척도를 사용하였고, Baron·Kenny(1986)의 3단계 매개효과 분석 방법을 활용하였다. 연구의 결과는 첫째, 죽음불안이 자아통합감에 미치는 영향력은 통계적으로 유의하였다. 둘째, 적용한 결과, 죽음불안과 자아통합감 간의 관계에서 심리적 안녕감이 완전매개 효과를 갖는 것으로 연구 결과가 나타났다. 이 연구에서는 노인의 자아통합감 문제를 효과적이고 긍정적으로 다루기 위해서는 노인의 죽음불안과 함께 노인의 심리적 안녕감 역시 간과하지 않아야 한다는 것을 밝혔다.

• 한국기계연구소 소보
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• 통권18호
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• pp.147-152
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• 1988

The dynamic simulation for automobile running on bumpy road is introduced. The modeling method that is a very close approximation to automobile is presented. Because the output printed at every integration time step is lots of amount, to save the time of interpretation of dynamic response, the ouptput data are interactively processed by PLOT88, also a configuration of automobile is generated by animated graphic displays using PADL and APPLICON.

• Structural Engineering and Mechanics
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• 제53권3호
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• pp.537-573
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• 2015

Multiple-step beams carrying intermediate lumped masses with/without rotary inertias are widely used in engineering applications, but in the literature for free vibration analysis of such structural systems; Bernoulli-Euler Beam Theory (BEBT) without axial force effect is used. The literature regarding the free vibration analysis of Bernoulli-Euler single-span beams carrying a number of spring-mass systems, Bernoulli-Euler multiple-step and multi-span beams carrying multiple spring-mass systems and multiple point masses are plenty, but that of Timoshenko multiple-step beams carrying intermediate lumped masses and/or rotary inertias with axial force effect is fewer. The purpose of this paper is to utilize Numerical Assembly Technique (NAT) and Differential Transform Method (DTM) to determine the exact natural frequencies and mode shapes of the axial-loaded Timoshenko multiple-step beam carrying a number of intermediate lumped masses and/or rotary inertias. The model allows analyzing the influence of the shear and axial force effects, intermediate lumped masses and rotary inertias on the free vibration analysis of the multiple-step beams by using Timoshenko Beam Theory (TBT). At first, the coefficient matrices for the intermediate lumped mass with rotary inertia, the step change in cross-section, left-end support and right-end support of the multiple-step Timoshenko beam are derived from the analytical solution. After the derivation of the coefficient matrices, NAT is used to establish the overall coefficient matrix for the whole vibrating system. Finally, equating the overall coefficient matrix to zero one determines the natural frequencies of the vibrating system and substituting the corresponding values of integration constants into the related eigenfunctions one determines the associated mode shapes. After the analytical solution, an efficient and easy mathematical technique called DTM is used to solve the differential equations of the motion. The calculated natural frequencies of Timoshenko multiple-step beam carrying intermediate lumped masses and/or rotary inertias for the different values of axial force are given in tables. The first five mode shapes are presented in graphs. The effects of axial force, intermediate lumped masses and rotary inertias on the free vibration analysis of Timoshenko multiple-step beam are investigated.

• 대한지리학회지
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• 제46권1호
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• pp.81-99
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• 2011

본 연구는 다각적으로 이루어지고 있는 물류산업의 공간적 연구를 종합적으로 정리하여 이를 체계화 하고자 함이다. 물류산업은 물류기능별 독립적 최적화, 전문화된 물류서비스를 제공하는 자재관리와 물적유통, 로지스틱스, 정보통신 기술과 경영이 포함된 공급사슬관리 단계로 발전하면서 복잡한 공간조직을 형성한다. 물류산업의 복잡한 공간조직은 지리공간과 가상공간, 분업과 통합, 매개화와 탈매개화로 체계화된다. 또한 이들 세 가지의 영역이 공간상에서 혼재하는 역동적 특성을 보인다. 이 역동적 특성은 정보통신 기술과 경제활동의 공간 간의 상호작용과 밀접한 관계가 있다.4

• Structural Engineering and Mechanics
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• 제38권2호
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• pp.211-229
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• 2011

In this paper, we present a new explicit procedure using periodic cubic B-spline interpolation polynomials to solve linear and nonlinear dynamic equation of motion governing single degree of freedom (SDOF) systems. In the proposed approach, a straightforward formulation was derived from the approximation of displacement with B-spline basis in a fluent manner. In this way, there is no need to use a special pre-starting procedure to commence solving the problem. Actually, this method lies in the case of conditionally stable methods. A simple step-by-step algorithm is implemented and presented to calculate dynamic response of SDOF systems. The validity and effectiveness of the proposed method is demonstrated with four examples. The results were compared with those from the numerical methods such as Duhamel integration, Linear Acceleration and also Exact method. The comparison shows that the proposed method is a fast and simple procedure with trivial computational effort and acceptable accuracy exactly like the Linear Acceleration method. But its power point is that its time consumption is notably less than the Linear Acceleration method especially in the nonlinear analysis.