• Journal of applied mathematics & informatics
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• 제15권1_2호
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• pp.211-225
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• 2004

A mixed type dual to a programming problem containing support functions in a objective as well as constraint functions is formulated and various duality results are validated under generalized convexity and invexity conditions. Several known results are deducted as special cases.

• Architectural research
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• 제12권1호
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• pp.39-47
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• 2010

This paper describes a topology optimization technique which can maximize the fundamental frequency of the structures. The fundamental frequency maximization is achieved by means of the minimization of modal strain energy as an inverse problem so that the strain energy based resizing algorithm is directly used in this study. The strain energy to be minimized is therefore employed as the objective function and the initial volume of structures is used as the constraint function. Multi-frequency problem is considered by the introduction of the weight which is used to combine several target modal strain energy terms into one scalar objective function. Several numerical examples are presented to investigate the performance of the proposed topology optimization technique. From numerical tests, it is found to be that the proposed optimization technique is extremely effective to maximize the fundamental frequency of structure and can successfully consider the multi-frequency problems in the topology optimization process.

• 한국농공학회논문집
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• 제52권5호
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• pp.19-26
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• 2010

This study was conducted to find out the reasonable optimum design method of agricultural reinforced concrete structures. Selected design variables are the dimension of concrete section, reinforced steel area, and objective function is formulated by cost function. To test the reliability, efficiency, possibility of application and reasonability of optimum design method, both continuous optimization method and mixed-discrete optimization method were applied to the design of reinforced concrete superstructure of aqueduct and application results were discussed. It is proved that mixed-discrete optimization method is more reliable, efficient and reasonable than continuous optimization method for the optimum design of reinforced concrete agricultural structures.

• 대한전기학회논문지:시스템및제어부문D
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• 제53권11호
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• pp.747-752
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• 2004

This paper presents an iterative linear matrix inequality (LMI) approach to the design of a static output feedback (SOF) stabilization controller. A linear penalty function is incorporated into the objective function for the non-convex rank constraint so that minimizing the penalized objective function subject to LMIs amounts to a convex optimization problem. Hence, the overall procedure results in solving a series of semidefinite programs (SDPs). With an increasing sequence of the penalty parameter, the solution of the penalized optimization problem moves towards the feasible region of the original non-convex problem. The proposed algorithm is, therefore, convergent. Extensive numerical experiments are Deformed to illustrate the proposed algorithm.

• 한국농공학회지
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• 제30권3호
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• pp.82-94
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• 1988

A growing attention has been paid to the optimum design of structures in recent years. Most studies on the optimum design of reinforced concrete structures has been mainly focussed to the design of structural members such as beams, slabs and columns, and there exist few studies that deal with the optimum design of large-scale concrete shell structures. The purpose of the present investigation is, therefore, to set up an efficient optimum design method for the large-scale reinforced concrete cylindrical shell structures like intake tower of reservoir. The major design variables are the dimensions and steel areas of each member of structures. The construction cost which is compo8ed of the concrete, steel, and form work costs, respectively, is taken as the objective function. The constraint equations for the design of intake-tower are derived on the basis of strength design method. The results obtained are summarized as follows 1. The efficient optimlzation algorithrns which can execute the automatic optimum design of reinforced concrete intake tower based on the strength design method were developed. 2. Since the objective function and design variables were converged to their optimum values within the first or second iteration, the optimization algorithms developed in this study seem to be efficient and stable. 3. When using the strength design method, the construction cost could be saved about 9% compared with working stress design method. Therefore, the reliability of algorithm was proved. 4. The difference in construction cost between the optimum designs with substructures and with entire structure was found to be small and thus the optimum design with substructures may conveniently be used in practical design. 5. The major active constraints of each structural member were found to be the 'bending moment constraint for slab, the minimum longitudinal steel ratio constraint for tower body and the shearing force, bending moment and maximum eccentricity constraints for footing, respectively. 6. The computer program developed in the present study can be effectively used even by an uneiperienced designer for the optimum design of reinforced concrete intake-tower on the basis of strength design method.

• Structural Engineering and Mechanics
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• 제72권2호
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• pp.181-190
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• 2019

Topology optimization of structures seeking the best distribution of mass in a design space to improve the structural performance and reduce the weight of a structure is one of the most comprehensive issues in the field of structural optimization. In addition to structures stiffness as the most common objective function, frequency optimization is of great importance in variety of applications too. In this paper, an efficient multi-objective Bi-directional Evolutionary Structural Optimization (BESO) method is developed for topology optimization of frequency and stiffness in continuum structures simultaneously. A software package including a Matlab code and Abaqus FE solver has been created for the numerical implementation of multi-objective BESO utilizing the weighted function method. At the same time, by considering the weaknesses of the optimized structure in single-objective optimizations for stiffness or frequency problems, slight modifications have been done on the numerical algorithm of developed multi-objective BESO in order to overcome challenges due to artificial localized modes, checker boarding and geometrical symmetry constraint during the progressive iterations of optimization. Numerical results show that the proposed Multiobjective BESO method is efficient and optimal solutions can be obtained for continuum structures based on an existent finite element model of the structures.

• 재활치료과학
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• 제8권4호
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• pp.7-18
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• 2019

목적 : 경두개 직류 자극과 강제 유도 운동 치료의 결합된 중재를 적용한 뇌졸중 환자의 회복과 관련된 연구 동향을 알아보고, 중재 계획 시, 도움이 될 수 있는 정보 및 근거를 제시하는 데 목적이 있다. 연구방법 : 전자 데이터베이스 PubMed, NDSL 등을 이용하여 2009년 1월부터 2018년 12월까지 10년간 온라인 데이터에 등록된 논문을 검색하였다. 주요 검색어로 'Transcranial direct current stimulation' or 'tDCS', 'Constraint-induced movement therapy' or 'CIMT', 'Upper extremity function', 'Upper limb', 'Stroke'을 혼용하여 사용하여 본 연구의 선정기준과 배제기준에 부합하는 6편의 논문을 최종 선정하여 분석하였다. 결과 : 경두개 직류 자극의 적용 전류의 세기, 적용시간 등과 강제 유도 운동 치료의 프로토콜은 다양한 방법으로 이루어져 있었지만, 경두개 직류 자극 직 후 CIMT를 시행하는 중재 절차는 동일하게 시행되었다. 중재 효과를 알아보기 위해 상지기능, 일상생활동작, 대뇌피질 활성도 평가 등이 사용되었다. 경두개직류 자극과 강제 유도 운동 치료의 결합된 중재는 뇌졸중 환자의 상지기능과 일상생활동작 개선에 효과적인 것으로 나타났으며, 대뇌피질의 활성화에도 유의미한 효과가 있는 것으로 나타났다. 결론 : 본 연구를 통해 경두개 직류 자극과 강제 유도 운동 치료의 결합된 중재 적용에 필요한 정보 제공 및 근거를 마련하였다. 추후 연구를 통해, 경두개 직류 자극의 자극시간과 전류의 세기, 전극의 부착 위치 등에 대한 일반화가 필요할 것이며 가장 적절한 강제 유도 운동 치료 프로토콜을 사용하여 큰 모집단을 대상으로 장기간 추적 관찰을 포함한 무작위 대조군 실험연구가 필요하다.

• 대한지역사회작업치료학회지
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• 제7권1호
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• pp.25-35
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• 2017

목적 : 본 연구의 목적은 수정된 강제유도 운동치료가 편마비 뇌성마비 아동의 상지 기능과 관련된 요소들에 미치는 영향을 알아보는 것이다. 연구방법 : 8세에서 11세 사이의 편마비 뇌성마비 아동 4명을 대상으로 실험을 실시하였다. 수정된 강제유도 운동치료는 하루 5시간 동안의 건측 제한과 이 시간동안 2시간의 환측의 집중적인 과제훈련, 주당 5회, 총 8주를 실시하였고, 수정된 강제유도 운동치료가 상지 기능과 관련된 요소에 미치는 영향을 확인하기 위하여 Jebsen Hand Function Test와 3차원 동작분석을 실시하였다. Jebsen Hand Function Test는 실험 2주마다 반복 측정을 실시하였고, 3차원 동작분석의 경우에는 실험 전과 실험 후에 측정을 실시하였다. 결과 : 수정된 강제유도 운동치료 후, Jebsen Hand Function Test에서는 하위 검사 모두에서 경과 시간의 유의한 감소가 나타났고(p<.05), 3차원 동작 분석 결과 수정된 강제유도 운동치료 적용 전에 비해 8주의 경과 후 손바닥 두드리기 검사와 검지 두드리기 검사에서 통계학적으로 유의한 감소가 나타났고(p<.05), 아래팔의 회내와 회외 운동에서는 수정된 강제유도 운동치료 적용 전에 비해 8주의 경과 후 통계학적으로 유의한 증가가 나타났다. 결론 : 본 연구의 결과를 통하여, 수정된 강제유도 운동치료는 편마비 뇌성마비 아동의 상지 기능과 관련된 요소를 효과적인 치료하는 방법임을 알 수 있었다. 그리고 향후 수정된 강제유도 운동치료를 위한 개별화된 적용 방법과 개인의 상태에 따른 다양한 적용 기간의 연구가 필요할 것으로 생각된다.

• Journal of Communications and Networks
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• 제7권4호
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• pp.471-477
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• 2005

This paper proposes an efficient constraint-based optimization model for the design of 3G mobile networks, such as universal mobile telecommunications system (UMTS). The model concerns about finding a set of sites for locating radio network controllers (RNCs) from a set of pre-defined candidate sites, and at the same time optimally assigning node Bs to the selected RNCs. All these choices must satisfy a set of constraints and optimize an objective function. This problem is NP-hard and consequently cannot be practically solved by exact methods for real size networks. Thus, this paper proposes a hybrid search strategy for tackling this complex and combinatorial optimization problem. The proposed hybrid search strategy is composed of three phases: A constraint satisfaction method with an embedded problem-specific goal which guides the search for a good initial solution, an optimization phase using local search algorithms, such as tabu algorithm, and a post­optimization phase to improve solutions from the second phase by using a constraint optimization procedure. Computational results show that the proposed search strategy and the model are highly efficient. Optimal solutions are always obtained for small or medium sized problems. For large sized problems, the final results are on average within $5.77\%$ to $7.48\%$ of the lower bounds.

• Earthquakes and Structures
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• 제18권1호
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• pp.45-56
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• 2020

The application of critical excitation method with displacement-based objective function for multi degree of freedom (MDOF) systems is investigated. To this end, a new critical excitation method is developed to find the critical input motion of a MDOF system as a synthetic accelerogram. The upper bound of earthquake input energy per unit mass is considered as a new constraint for the problem, and its advantages are discussed. Considering this constraint, the critical excitation method is then used to generate synthetic accelerograms for MDOF models corresponding to three shear buildings of 10, 16, and 22 stories. In order to demonstrate the reliability of generated accelerograms to estimate dynamic response of the structures, three target ground motions with considerable level of energy contents are selected to represent "real critical excitation" of each model, and the method is used to re-generate these ground motions. Afterwards, linear dynamic analyses are conducted using these accelerograms along with the generated critical excitations, to investigate the key parameters of response including maximum displacement, maximum interstory drift, and maximum absolute acceleration of stories. The results show that the generated critical excitations can make an acceptable estimate of the structural behavior compared to the target ground motions. Therefore, the method can be reliably implemented to generate critical excitation of the structure when real one is not available.