• Proceedings of the KSME Conference
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• 2001.11a
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• pp.746-752
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• 2001

Design sensitivity analysis for nonlinear structural problems has been emerged in the last decade as a glowing area of engineering research. As a result, theoretical formulations and computational algorithms have already developed for design sensitivity of nonlinear structural problems. There is not enough research for practical nonlinear problems using multi-element, due to difficulties of implementation into FEA. Therefore, nonlinear response analysis for stiffened shell which consists of Mindlin plate and Timoshenko beam, was considered. Specially, it presents the backward-Euler method which is adopted to describe an exact yield state in the stress computation procedure. Then, design sensitivity analysis of nonlinear structures, particularly elasto-perfectly-plastic structure, is developed using direct differentiation method. The accuracy of the developed sensitivity analysis was compared with the central finite difference method. Finally, on the basis of above results, design improvement for stiffened shell is suggested.

• Structural Engineering and Mechanics
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• v.6 no.8
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• pp.857-870
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• 1998

This paper deals with a special class of inverse problems in discrete structural plasticity involving the identification of elastic limits and hardening moduli on the basis of information on displacements. The governing equations lead naturally to a special and challenging optimization problem known as a Mathematical Program with Equilibrium Constraints (MPEC), a key feature of which is the orthogonality of two sign-constrained vectors or so-called "complementarity" condition. We investigate numerically the application of two simple algorithms, both based on the use of the general purpose nonlinear programming code CONOPT accessed via the GAMS modeling language, for solving the suitably reformulated problem. Application is illustrated by means of two numerical examples.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.962-969
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• 2009

The market of building construction has been competitive in Hong Kong, perhaps as anywhere else in the world. The barrier to entry is low because there are relatively low requirements on the three factors of production - technology, manpower and finance. The prevailing building technology is traditional and labour-intensive. There is also not much need of capital because clients' periodic payments have been the main source of project finance. Further, capitalizing on trade sub-contracting, contractors have been able to keep their direct labour-force small and to transfer much of their business risk to the sub-contractors. Based on interviews to solicit the perception of a sample of building contractors on the particular issues of construction finance, we present the findings in this paper and discuss the various implications. We believe that the current practice of construction financing is both the cause and effect of the competition within, and the competitiveness of, the building construction sector in Hong Kong. We conclude that the building construction sector is "locked or stuck" in this "equilibrium" of traditional technology, reliance on clients' finance and exploitation of sub-contracting. In this "equilibrium" state, there is hardly any motivation for contractors to engage themselves in product or process innovation. Consequently, any talk of industry reform or innovation could only remain just that. We believe that this problem is not unique in Hong Kong. The building construction sector in many other developed and developing economies is posed with similar if not the same problems and constraints. We conclude that there has to be some "external forces" to bring this "equilibrium" state to a higher level "equilibrium" one where higher value-added building construction services are supplied and demanded. This is a state where building contractors possessing innovative technology, better financial and manpower resources could thrive to build better buildings with innovative building methods and processes.

• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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• pp.313-318
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• 1994

It is well known that the neural network can be used as an universal approximater for functions and functionals. But these theoretical results are just an existence theorem and do not lead to decide the suitable network structure. This doubfulness whether a certain network can approximate a given function or not, brings about serious stability problems when it is used to identify a system. To overcome the stability problem, We suggest successive identification and control scheme with supervisory controller which always assures the identification process within a basin of attraction of one stable equilibrium point regardless of fittness of the network.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1993.10a
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• pp.47-54
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• 1993

This paper is concerned with the geometrically nonlinear behavior of elastic systems under conservative loading conditions. In particular, the topic are snap through problems and the arc-length method to pass limit points of space trusses is used. And numerical examples are presented to trace nonlinear equilibrium paths.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.3 no.2
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• pp.173-177
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• 2003

In the first part an overview on fuzzy sets and fuzzy numbers is given. A detailed treatment of these notions is introduced in [1,2,3]. This sintetically presentation is useful in understanding and in developping the applications in context problems. In the second part, fuzzy context model is given as an application of fuzzy sets and the fuzzy equilibrium equation is solved [4,5].

• Steel and Composite Structures
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• v.18 no.5
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• pp.1119-1127
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• 2015

A finite-element model for beams with partially delaminated layers is used to investigate their behavior. In this formulation account is taken of lateral strains and the first-order shear deformation theory is used. Both displacement continuity and force equilibrium conditions are imposed between the regions with and without delamination. Numerical results of the present model are presented and its performance is evaluated for static and dynamic problems.

• Journal of the Korean Mathematical Society
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• v.35 no.1
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• pp.135-148
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• 1998

We propose the new controls constructed via the second or direct method of Liapunov to solve the collision avoidance control problems for moving objects and a robot arm in the plane. We also explicate the controlling effect by the simulations.

• Journal of the Korean Chemical Society
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• v.64 no.1
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• pp.19-29
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• 2020

We analyzed the representations of acid-base models in 4 kinds of Chemistry I and 4 kinds of Chemistry II textbooks of the 2009 revised curriculum, and 9 kinds of Chemistry I textbooks and 6 kinds of chemistry II textbooks of the 2015 revised curriculum in this study. The problems of the textbook were divided into the problems of definitions and the representations of the logical thinking. As a result of the study, the lack of the concept of chemical equilibrium had a problem with the representation of reversible reactions in the definition of the Brønsted-Lowry model in the Chemistry I textbooks of 2009 revised curriculum, it also appeared to persist in Chemistry I textbooks of 2015 revised curriculum which contains the concept of chemical equilibrium. The representations of logical thinking were related to particle kinds of conservation logic, combinational logic, particle number conservation logic, and proportion logic. There were few problems related to representation of logical thinking in Chemistry I textbook in 2009 revision curriculum, but more problems of representations related to logics are presented in Chemistry I textbooks in 2015 revision curriculum. Therefore, as the curriculum is revised, the representations of chemistry textbooks related to acid and base models need to be changed in a way that can help students' understanding.

• The Journal of Fisheries Business Administration
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• v.23 no.2
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• pp.53-67
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• 1992

It has been recognized, virtually from the time of its inception, that fisheries economics, like other aspects of resource economics, should ideally be cast in capital-theoretic terms. The fish population or biomass can be viewed as a capital stock in that, like conventional or man-made capital, it is capable of yielding a sustainable consumption flow through time. This study is to introduce the optimal control theory which was extended from the theory of calculus of variations into the study of former static theory of fisheries economics started by Gordon (1954). The optimal control theory eliminated the inadequacies of the classical techniques to a large extent. From this point of view, this study, on the base of Schaefer model, summerizes most of major results achieved so far, but does so in a manner such that the links with capital theory are made transparent. This study explores two sets of problems. The first concerns the optimal approach to the equilibrium stock, i.e. the optimal investment policy. The second set of problems arises from the relaxation of the highly restrictive assumption of autonomy (i.e. the assumption that the parameters are independent of time), then concludes the relaxation of linearity assumption together with the complexities caused by that.