• Bulletin of the Society of Naval Architects of Korea
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• v.27 no.1
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• pp.45-56
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• 1990

This study deals with the nonlinear strength analysis of laminated composite cylindrical shells to find the optimum structure of pressure vessel. By applying the F.E.M. using the 8-node degenerated Isoparametric shell element and Total Lagrangian formulation and being adopted Newton-Raphson method with incremental load as a solution scheme. the optimum structure is found from the viewpoint of minimum displacement. As a results of linear analysis on the 9 cases of laminated structure, $[50^{\circ}/-50^{\circ}]$ composition of the shell laminate give the minimum deflection. In case of the nonlinear analysis by applying Quadratic Failure Criteria on laminated combination $[{\theta}^{\circ}/-{\theta}^{\circ}]$, shell laminate structure of ${\theta}=50^{\circ}$ under external uniform pressure was founded as a optimum structure and ${\theta}=50^{\circ}$ for the case of external and axial loading combined.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.339-342
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• 2017

Geometric transform of an image is used to image correction. Ridid-Body, Simlilary transform, etc, many correction methods are exist in computer vision. Image warping is used to correction for image with perspective. To image warping I extracted 4 feature point about warping position. But It is difficult to extract 4 points accurately and warping result with these point is occurs error over 3 or 4 pixel at warping position. So I used template matching to extract 4 points correctly and selected repeatedly 2 points of 4 points because to confirm result correctly. positions of 2 points are changed in near of 3 by 3 pixel and warped each change. So I selected optimal 4 points with a error of less than 1 pixel and finally, warped image using optimal points. For this way is possible to obtain optimum result.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.16 no.4
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• pp.431-437
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• 2003

In this paper, an approximate optimization program based on GUI(graphic user interface) environment is developed. This program is coded by using Fortran and Visual basic. Fortran is used to Progress approximate optimization process. Visual basic is used to make user environment for user to use conveniently. Inside of this program, it uses two independent programs. One is commercial program, ANSYS, and the other is optimization program, PLBA(Pshenichny-Lim-Belegundu Arora). The former is used to obtain approximate equation of stress and displacement of a structure. The latter is used to solve approximate optimization. This algorithm uses second-order information of a function and active set strategy. This program is connecting ANSYS and PLBA. And it progress the process repeatedly until it obtain optimum value. As a method of approximate optimization, sequential design domain(SDD) is introduced. SDD starts with a certain range which is offseted from midpoint of an initial design domain and then SDD of the next step is determined by optimal point of a prior step.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.14 no.3
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• pp.339-348
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• 2001

More often a commercial package for the structural analysis is necessary in the structural optimum design. In this case the task of combining the package with an optimization program must be required, hut it is not so simple because interchanging some data between them is difficult. Sequential approximate optimization is currently used as a natural way to overcome the hard task. If sequential approximate optimization has wide side constraints that the lower limit of design variables is very small and their upper limit is very large, it is not so easy to obtain approximated functions accurately for the whole design domain. This paper proposes a sequential design domain method, which is very useful to carry out sequential approximate optimization in this case. In this paper, the response surface methodology is used to obtain approximated functions and the orthogonal array is used for design of experiments. The sequential approximate optimization of 3-bar and 10-bar trusses is demonstrated to verify the reliability of the sequential design domain method.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.529-535
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• 2017

In this paper the laminate design parameters are researched to maximize the performance index of a composite pressure vessel. The pressure-resistant performance and the light-weight concept with contained internal space are implied in the performance index. To maximize the performance index, the three design variables that the thickness of each of helical and hoop layers and the length of hoop layer are considered under the assumption of fixed internal space. To optimize the variables, the response surface method is introduced for construction of the surrogate model and the ANOVA(analysis of variance) is performed to evaluate the effects of the variables. The optimization problem is formulated to maximize performance index under the burst pressure constraint. To verify the effectiveness of the research, numerical analyses are performed for the optimum model.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.4
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• pp.405-414
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• 2011

Recently, the development of several hundreds of kW scale PCS for fuel cell generation is required as commercialization process of distributed generation systems using high temperature fuel cells such as MCFC begins. This paper proposes and optimized topology suitable for MCFC fuel cell generation system and LCL filter design method considering voltage quality of local loads such as MBOP. An interleaving technique is applied to step-up DC-DC converter, optimized number of phases is determined considering efficiency and volume. Also, a LCL filter design method is proposed considering quality of current injected to the grid as well as that of voltage across the local load. The proposed PCS system is validated through reduced 1kW prototype.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.6
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• pp.1139-1148
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• 2000

To treat and recycle a large quantity of converter slag. the milling properties of -14/ +24 mesh-sized slag has been considered. The optimal conditions in milling process were investigated for producing powder-type slag and the required consumption was derived for the economical grinding. The characteristics of milling processes were studied in the variation of the rotational speed, milling time, filling ratio of ball, and size and amount of feed. The grinding efficiency was also examined. The optimal rotational speed in this experimental condition was observed to be the value of 79% of critical speed. The extent of grinding was increased with increasing the grinding time. but the efficiency of milling was decreased with the time. 50% ball filling was shown to have the optimal grinding effect, and less amount and small-sized feed made the milling efficiency high. As the result, using Bond's equation, power required for efficient milling was considered and the highest value was observed in the condition of high grinding time and optimal rotational speed.

• Journal of the Korean Institute of Gas
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• v.24 no.1
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• pp.1-9
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• 2020

Because the expenditure of LNG liquefaction processes are high in a LNG project, it is very important to find a suitable liquefaction process model and optimal operating conditions for a project. Various configurations of LNG liquefaction processes have been suggested, and therefore it takes a lot of time and manpower to compare all of these models in order to select an appropriate liquefaction process for a project. A superstructure model can include multiple options in one model and can contribute to decide the best configuration and operating conditions at the same time. This study developed a superstructure model including multiple process options for SMR (Single Mixed Refrigerant) liquefaction process and optimized it. The results showed that the optimization results of the superstructure model have similar values with optimization results of the separate SMR model.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.94-94
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• 2012

기후변화 대응은 온실가스 배출의 감축 및 흡수원을 확대하는 완화(mitigation)와 기후변화로 인한 영향과 취약성을 평가하여 피해를 최소화하는 적응(adaptation)이 상호 균형을 이루어야 한다. 지금까지 우리나라를 포함한 국제사회는 대부분 완화를 위해 노력해 왔지만 최근에 들어 완화만으로는 기후변화의 영향을 회피하기 어렵다는 사실이 인식되면서 적응 연구가 다양하게 이루어지고 있다. 이러한 상황 가운데 적응 계획의 실현화를 위해서 기후변화의 불확실성을 고려한 의사 결정에 관한 연구가 반드시 뒷받침 되어야 한다. 기존의 일반적인 의사결정은 다양한 미래 시나리오들 하에 가장 높은 효용을 가져오는 최적(Optimal)의 대안을 채택하는 고전적 결정분석(Classical Decision Analysis)의 프레임을 사용하였다. 그러나 기후변화로 인해 미래 기후 예측 시나리오의 불확실성이 증대되면서 최근에는 최적의 대안을 선정하는 것에 대한 의문이 제기되며 새로운 기법에 대한 연구가 이루어지고 있다. 본 연구는 기후변화의 불확실성을 고려하기 위한 새로운 의사결정 기법인 로버스트 의사결정(Robust Decision Making, RDM)을 실제유역의 적용을 통해 제안하고자 한다. 로버스트 의사결정은 RAND에서 개발한 것으로 최적의 대안을 채택하는 것 대신 모든 가능한 시나리오 가운데 가장 안정적인 전략을 채택한다는 것에서 기존의 의사결정 체계와 차이가 있다. 연구의 적용은 안동-임하댐 유역을 대상으로 온실 가스 배출 시나리오 A1B, A2, B1시나리오에 대해 15개의 GCMs에서 산출된 기후자료를 기반으로 기후변화의 시나리오를 작성하였으며, 다양한 측면의 대안을 설정하여 용수공급량을 평가하였다. 연구의 결과로 산정될 각 대안 별 안정적인 정도와 취약한 시나리오에 대한 정보는 기후변화의 불확실성을 전제한 의사결정을 할 때 로버스트 의사결정이 갖는 장점이 될 수 있다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.2
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• pp.207-212
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• 2011

A hydraulic breaker is an attachment installed at the end of excavator arm and is used for breaking. As per the authors' knowledge, there have been no research results on reducing the weight of the hydraulic breaker even though this weight reduction is very important for improving the performance of the excavator. In this study, we minimize the weight of the housing of the hydraulic breaker under normal operating conditions, while the maximum stress of the housing is lower than the allowable stress. A meta-model, which is generated by using the CAE results for the sampling design points determined by an orthogonal array, is used to solve the minimization problem. The weight of the housing according to the optimal design is found to be lower than the original weight by 4.8% while satisfying the constraint on the maximum stress.