• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.6
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• pp.77-82
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• 2008

This paper presents a Reliability-Based Topology Optimization(RBTO) using the Evolutionary Structural Optimization(ESO). An actual design involves some uncertain conditions such as material property, operational load and dimensional variation. The Deterministic Topology Optimization(DTO) is obtained without considering the uncertainties related to the uncertainty parameters. However, the RBTO can consider the uncertainty variables because it has the probabilistic constraints. In order to determine whether the probabilistic constraints are satisfied or not, simulation techniques and approximation methods are developed. In this paper, the reliability index approach(RIA) is adopted to evaluate the probabilistic constraints. In order to apply the ESO method to the RBTO, sensitivity number is defined as the change in the reliability index due to the removal of the ith element. Numerical examples are presented to compare the DTO with the RBTO.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.10
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• pp.66-76
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• 2002

Automated welding and soldering are an important manufacturing issue in order to lower the cost, increase the quality, and avoid labor problems. An off-line programming, OLP, is one of the powerful methods to solve this kind of diversity problem. Unless an OLP system is ready for the path optimization in welding and soldering, the waste of time and cost is unavoidable due to inefficient paths in welding and soldering processes. Therefore, this study attempts to obtain path optimization using a genetic algorithm based on artificial intelligences. The problem of welding path optimization is defined as a conventional TSP (traveling salesman problem), but still paths have to go through welding lines. An improved genetic algorithm was suggested and the problem was formulated as a TSP problem considering the both end points of each welding line read from database files, and then the transit problem of welding line was solved using the improved suggested genetic algorithm.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2015.07a
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• pp.308-309
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• 2015

최근 들어 일반인들도 다중 콥터와 4k 고성능 카메라를 장착한 상용 드론을 구매하여 자신의 취미 활동용으로 사용하고 있다. 드론을 이용한 많은 동호회가 생겨나고 1인 1드론, 개인용 드론의 시대가 시작되고 있다. 또한 사물인터넷의 시대에 걸맞게 아두이노, 라즈베리파이와 같은 오픈하드웨어 플랫폼과 오픈 소스를 이용하고 저가형 3D printer 의 보급으로 자신만의 독특한 형태를 지니는 기체 제작을 시작하고 있다. 이에 본 논문에서는 3D 캐드를 이용한 위상최적화 기법을 적용하여 기존 상용 기체의 강성은 그대로 유지하되 기체 프레임 무게를 절반으로 줄인다. 또한, 풍동실험을 진행해서 기존 기체에서 발생하는 유체흐름을 분석하고 새로운 기체를 적용했을 경우에도 유사한 유체흐름이 나타나도록 설계하여 3D 프린터를 사용하여 제작하였다.

• Journal of the Korea Institute of Military Science and Technology
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• v.21 no.3
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• pp.264-278
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• 2018

The support structure of an optical mirror system is the one of the important design elements because the one affects the optical aberrations of the mirror surface. In this paper, Lagrange equation of the moving body of the fast steering mirror system(FSM) has been formulated to use with optimization design. Major goals for optimization are to assign the reasonably flexible stiffness to the structure and to enhance the first natural frequency of the mirror and support system in aid of more affordable control bandwidth for the FSM. Pursuing these purposes with the proposed method, the finite element analysis(FEA), optimization technique and the Zernike polynomial estimation are used for the design effects. It is concluded that the proposed approach for design well guides toward the desired design goals with regards to both structural and optical performances.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.16 no.1
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• pp.1-8
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• 2003

Topology optimization has been evolved into a very efficient conceptual design tool and has been utilized into design engineering processes. Traditional topology optimization has been using homogenization method and optimality criteria method. homogenization method provides relationship equation between structure which includes many holes and stiffness matrix in FEM. Optimality criteria method is used to update design variables while maintaining that volume fraction is uniform. Traditional topology optimization has advantage of good convergence but has disadvantage of too much convergency time. In one way to solve this problem, element removal method using the criterion of an average stress is presented. As the result of examples, it is certified that convergency time is very reduced.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.8A
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• pp.821-828
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• 2008

In this paper, we present an optimized design of RS(23,17) decoder for UWB, which uses the pipeline structured-modified Euclidean(PS-ME) algorithm. Firstly, the modified processing element(PE) block is presented in order to get rid of degree comparison circuits, registers and MUX at the final PE stage. Also, a degree computationless decoding algorithm is proposed, so that the hardware complexity of the decoder can be reduced and high-speed decoder can be implemented. Additionally, we optimize Chien search algorithm, Forney algorithm, and FIFO size for UWB specification. Using Verilog HDL, the proposed decoder is implemented and synthesized with Samsung 65nm library. From synthesis results, it can operate at clock frequency of 250MHz, and gate count is 17,628.

• Journal of Korean Society of Steel Construction
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• v.15 no.6 s.67
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• pp.603-610
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• 2003

A damage identification technique using static displacement data is developed to asses s the structural integrity of bridge structures.As such, the relationship between static displacement and stiffness is derived, and the optimization technique utilized.Comparisons with numerical and experimental tests are performed to investigate the practical applicability of the proposed method.Various damage scenarios are considered by varying damage-width as well as damage-degree. The influence of noise in identifying the damage is also numerically investigated.Finally, the applicability and limitation of the proposed method are discussed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.9
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• pp.2179-2182
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• 2009

Recently, the development of new structural model in optical mechanical system is required to be started from the conceptual design with low cost, high performance and quality. In this point, a structural-topological shape of system concerned with conceptual design of mechanical structure has a great effect on performance of the system such as the structural rigidities and weight reduction. In this paper, the optimization design methodologies are presented in the design stages of large optical structure. First, using topology optimization, we obtain the optimal layout and the reinforcement of structure, and then carry out the detail designs using size optimization and multidisciplinary optimization technique. As an example, these methods were applied to the design of large mirror structure.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.1
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• pp.39-46
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• 2017

In this paper, a model updating procedure based on the response surface method combined with the multi-objective optimization was proposed and applied for updating of the FE models representing a low-rise reinforced concrete building before and after the seismic retrofit. The dynamic properties to be matched were obtained from vibration tests using a small shaker system. By varying the structural parameters according to the central composite design, analysis results from the initial FE model using a commercial software were collected and used to produce two regression functions each of which representing the errors in the natural frequencies and mode shapes. The two functions were used as the objective functions for multi-objective optimization. Final solution was determined by examining the Pareto solutions with one iteration. The parameters representing the stiffnesses of existing concrete, masonry, connection stiffness in expansion joint, new concrete, retrofitted members with steel section jacketing were selected and identified.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.6
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• pp.1381-1388
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• 1993

This paper presents a method for the simultaneous optimal design of structural and control systems. Sensitivities of performance index with respect to structural design variables are analyzed. The structural design variables are optimized to minimize the performance index by use of conjugate gradient method. The method is applied to a half model of an active vehicle suspension system with elastic body moving on a randomly profiled road. The suspension control force of an optimally controlled system in the presence of measurement errors are calculated by use of linear quadratic Gaussian control theory and Kalman filter theory. The performance index contains ride comfort, road holding and working space of suspension. The structural design variables taken are stiffness, daming properties and the position of the suspension system. The random road profile considered as colored noise is shaped from white noise by use of shaping filter. The performance of an optimal simultaneous structure/control system is compared with that of an optimal controlled system.