• Journal of KIISE:Software and Applications
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• v.36 no.8
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• pp.673-682
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• 2009

Recently, photo sharing and publishing based Social Network Sites(SNSs) are increasingly attracting the attention of academic and industry researches. Unlike the face recognition environment addressed by existing works, face annotation problem under SNSs is differentiated in terms of daily updated images database, a limited number of training set and millions of users. Thus, conventional approach may not deal with these problems. In this paper, we proposed a face annotation method for sharing and publishing photographs that contain faces under a social network service using random projection, non-linear regression and representational state transfer. Our experiments on several databases show that the proposed method records an almost constant execution time with comparable accuracy of the PCA-SVM classifier.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.1
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• pp.45-53
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• 2015

Large-capacity of household washing machine can become unbalanced during the dehydration process. To solve this problem, several types of suspensions have been installed in a washing machine. In this study, physical tests were carried out on a frictional suspension, and the nonlinear characteristics were modeled by combining several simple physical models. The parameters were estimated based on the least squares solution. The simulation and test results were compared to verify the validity of the friction damper model.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.04a
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• pp.240-244
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• 2005

In this study a simple model is developed that predicts impact damage in a composite laminate using an analytical model. The model uses a non-linear approximation method (Rayleigh-Ritz) and the large deflection plate theory to predict the number of failed plies and damage area in a quasi-isotropic composite circular plate (axisymmetric problem) due to a point impact load at its centre. It is assumed that the deformation due to a static transverse load is similar to that occurred in a low velocity impact. It is found that the model, despite its simplicity, is in good agreement with FEM predictions and experimental data for the deflection of the composite plate and gives a good estimate of the number of failed plies due to fibre breakage. The predicted damage zone could be used with a fracture mechanics model developed by the second investigator and co-workers to calculate the compression after impact strength of such laminates. This approach could save significant running time when compared to FEM solutions.

• Earthquakes and Structures
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• v.12 no.5
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• pp.543-557
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• 2017

Results of an extensive study aiming to properly extend the well known pushover analysis into 3-D problems of asymmetric buildings are presented in this paper. The proposed procedure uses simple, 3 DOF, one-story models with shear-beam type elements in order to quantify the effects of inelastic torsional response of such buildings. Correction coefficients for the response quantities at the "stiff" and "flexible" sides are calculated using results from non-linear time history analyses of the simple models. Their values are then applied to the results of a simple, plane pushover analysis of the detailed building models. Results from the application of the new method for a set of three, conventionally designed, five-story buildings with high values of uniaxial eccentricities are compared with those obtained from multiple non-linear dynamic time history analyses, as well as from similar pushover methods addressing the same problem. This initial evaluation indicates that the proposed procedure is a clear improvement over the simple (conventional) pushover method and, in most cases, more accurate and reliable than the other methods considered. The accuracy, however, of all these methods is reduced substantially when they are applied to torsionally flexible buildings. Thus, for such challenging problems, use of inelastic dynamic analyses for a set of two component earthquake motions appears to be the preferable solution.

• Proceedings of the Korean Information Science Society Conference
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• 2007.10c
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• pp.371-374
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• 2007

본 논문에서는 고정 비용을 고려한 비선형 수송문제(Fixed Charge Non-linear Transportation Problem)에 대해 다룬다. 이는 한 종류의 상품을 다수의 공급처에서 다수의 수급처로 수송할 때, 총 수송비용과 고정 비용이 최소가 되도록 각 공급처와 수급처 간의 수송량을 결정하는 문제이다. 현재 비선형 수송문제에 대한 다양한 해법들이 제안되고 있으며 그 중에서도 메타 휴리스틱을 이용한 해법들이 가장 활발히 연구되고 있다. 본 논문에서는 메타 휴리스틱 방법들중에 가장 널리 이용되고 있는 유전 알고리즘을 이용한 해법을 제시하고자 한다. 유전 알고리즘을 적용함에 있어서 제일 첫 관문은 해의 유전자표현을 어떻게 나타낼 것인가이다. 본 논문에서는 수송문제의 해를 걸침나무로 표현할 수 있다는 점 에 착안하여 다양한 트리 표현법을 수송문제에 적용해 보고 수치 실험을 통해 그 성능에 대한 비교 연구를 한다.

• Journal of Mechanical Science and Technology
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• v.19 no.4
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• pp.947-957
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• 2005

In this study a simple model is developed that predicts impact damage in a composite laminate avoiding the need of the time-consuming dynamic finite element method (FEM). The analytical model uses a non-linear approximation method (Rayleigh-Ritz) and the large deflection plate theory to predict the number of failed plies and damage area in a quasi-isotropic composite circular plate (axisymmetric problem) due to a point impact load at its centre. It is assumed that the deformation due to a static transverse load is similar to that oc curred in a low velocity impact. It is found that the model, despite its simplicity, is in good agreement with FEM predictions and experimental data for the deflection of the composite plate and gives a good estimate of the number of failed plies due to fibre breakage. The predicted damage zone could be used with a fracture mechanics model developed by the second investigator and co-workers to calculate the compression after impact strength of such laminates. This approach could save significant running time when compared to FEM solutions.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.969-972
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• 2007

수송문제는 산업공학 및 전자계산학 분야에서 중요한 문제 중의 하나로 인식된다. 수송문제가 시설을 수립하거나 고객들의 요구를 이행하기 위한 추가적인 고정 비용과 연관될 때, 이를 고정비용을 고려한 비선형 수송문제(Fixed Charge Non-linear Transportation Problem)라 한다. 고정비용을 고려한 비선형 수송문제는 한 종류의 상품을 다수의 공급처에서 다수의 수급처로 수송할 때, 수송비용과 고정비용이 최소가 되도록 수송량을 결정하는 문제이다. 본 논문에서는 이 비선형 수송문제에 가장 많이 쓰이는 메타 휴리스틱 방법들 중 유전 알고리즘을 이용한 해법을 제시한다. 유전 알고리즘을 적용함에 있어서 가장 중요한 것 중에 하나는 해의 유전자표현을 어떻게 나타낼 것인가 인데, 본 논문에서는 수송문제의 해를 걸침나무로 표현할 수 있다는 점에 착안하여 유전자 표현법들을 수송문제에 적용해 보고 수치 실험을 통해 그 성능에 대한 비교를 한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.248-251
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• 2007

본 논문에서 다루는 고정 비용을 고려 한 비 선형 수송문제 (Non-linear Transportation Problem)는 한 종류의 상품을 다수의 공급처 에 서 다수의 수요처로 수송 할 때, 총 수송비용 및 고정비용이 최소가 되도록 각 공급처와 수요처간의 수송량을 결정하는 문제로 현재 비선형 수송문제에 대한 다양한 해법들이 제안되고 있으며 그중에도 메타 휴리스틱이 가장 활발히 연구되고 있다. 본 논문에서는 이 메타휴리스틱 방법들 중에 가장 주목받고 있는 유전 알고리즘을 이용하여 비선형 수송문제에 대한 해법을 제시하고자 한다. 유전 알고리즘을 적용함에 있어서 가장 중요한 것 중에 하나가 어떻게 해를 유전자 표현으로 나타낼 것인가 인데 본 논문에서는 수송문제의 해를 걸침나무로 표현할 수 있다는 점에 착안하여 다양한 트리 표현법을 수송 문제에 적용해 보고 수치 실험을 통해 그 성능에 대한 비교 연구를 한다.

• Structural Engineering and Mechanics
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• v.29 no.5
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• pp.489-504
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• 2008

In piezoelectric flexible structures, the contribution of vibration modes to the dynamic response of system may change with the location of piezoelectric actuator patches, which means that the ability of actuators to control vibration modes should be taken into account in the development of modal reduction model. The spatial $H_2$ norm of modes, which serves as a measure of the intensity of modes to system dynamical response, is used to pick up the modes included in the reduction model. Based on the reduction model, the paper develops the state-space representation for uncertain flexible tructures with piezoelectric material as non-collocated actuators/sensors in the modal space, taking into account uncertainties due to modal parameters variation and unmodeled residual modes. In order to suppress the vibration of the structure, a dynamic output feedback control law is designed by imultaneously considering the conflicting performance specifications, such as robust stability, transient response requirement, disturbance rejection, actuator saturation constraints. Based on linear matrix inequality, the vibration control design is converted into a linear convex optimization problem. The simulation results show how the influence of vibration modes on the dynamical response of structure varies with the location of piezoelectric actuators, why the uncertainties should be considered in the reductiom model to avoid exciting high-frequency modes in the non-collcated vibration control, and the possiblity that the conflicting performance specifications are dealt with simultaneously.

• Computational Structural Engineering
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• v.10 no.2
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• pp.149-160
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• 1997

Mechanical structures are composed of substructures connected by joints and boundary elements. While the finite element representation of plain substructures is well developed and reliable, joints have a lot of uncertainties in being accurately modelled and affect dynamic behavior of a total system. In order to improve the accuracy of a finite element model, a new method is proposed, in which reduced finite element model is combined with a system identification technique. After substructures except joints are modelled with finite element method and joint properties are represented by parameter states, non-linear state equation is derived in which parameter states are multiplied by physical states such as displacements and velocities. So the joint parameter identification is transformed into non-linear state estimation problem. The methods are tested and discussed numerically and the feasibility for physical application has been demonstrated through two example structures.