• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2009년도 IWAIT
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• pp.714-718
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• 2009

3D reconstruction of a human face from an image sequence remains an important problem in computer vision. We propose a method, based on a factorization algorithm, that reconstructs a 3D face model from short image sequences exhibiting rotational motion. Factorization algorithms can recover structure and motion simultaneously from one image sequence, but they usually require that all feature points be well tracked. Under rotational motion, however, feature tracking often fails due to occlusion and frame out of features. Additionally, the paucity of images may make feature tracking more difficult or decrease reconstruction accuracy. The proposed 3D reconstruction approach can handle short image sequences exhibiting rotational motion wherein feature points are likely to be missing. We implement the proposal as a reconstruction method; it employs image sequence division and a feature tracking method that uses Active Appearance Models to avoid the failure of feature tracking. Experiments conducted on an image sequence of a human face demonstrate the effectiveness of the proposed method.

• Steel and Composite Structures
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• 제34권6호
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• pp.891-907
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• 2020

Many studies reveal that during destructive earthquakes, most of the structures enter the inelastic phase. The amount of hysteretic energy in a structure is considered as an important criterion in structure design and an important indicator for the degree of its damage or vulnerability. The hysteretic energy value wasted after the structure yields is the most important component of the energy equation that affects the structures system damage thereof. Controlling this value of energy leads to controlling the structure behavior. Here, for the first time, the hysteretic behavior and energy dissipation capacity are assessed at presence of elliptical braced resisting frames (ELBRFs), through an experimental study and numerical analysis of FEM. The ELBRFs are of lateral load systems, when located in the middle bay of the frame and connected properly to the beams and columns, in addition to improving the structural behavior, do not have the problem of architectural space in the bracing systems. The energy dissipation capacity is assessed in four frames of small single-story single-bay ELBRFs at ½ scale with different accessories, and compared with SMRF and X-bracing systems. The frames are analyzed through a nonlinear FEM and a quasi-static cyclic loading. The performance features here consist of hysteresis behavior, plasticity factor, energy dissipation, resistance and stiffness variation, shear strength and Von-Mises stress distribution. The test results indicate that the good behavior of the elliptical bracing resisting frame improves strength, stiffness, ductility and dissipated energy capacity in a significant manner.

• Structural Engineering and Mechanics
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• 제41권1호
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• pp.113-137
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• 2012

Frame structures with viscoelastic (VE) dampers mounted on them are considered in this paper. It is the aim of this paper to compare the dynamic characteristics of frame structures with VE dampers when the dampers are modelled by means of different models. The classical rheological models, the model with the fractional order derivative, and the complex modulus model are used. A relatively large structure with VE dampers is considered in order to make the results of comparison more representative. The formulae for dissipation energy are derived. The finite element method is used to derive the equations of motion of the structure with dampers and such equations are written in terms of both physical and state-space variables. The solution to motion equations in the frequency domain is given and the dynamic properties of the structure with VE dampers are determined as a solution to the appropriately defined eigenvalue problem. Several conclusions concerning the applicability of a family of models of VE dampers are formulated on the basis of results of an extensive numerical analysis.

• 한국항해항만학회지
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• 제26권4호
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• pp.441-447
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• 2002

전세계적인 인구증가와 산업화로 인하여 육지면적의 부족, 육상자원의 고갈 등의 문제로 해양의 이용 및 개발의 관심이 늘어나고 있으며, 환경친화적인 해양공간을 확보하기 위하여 초대형 부유식 해상구조물에 대한 기술개발이 요구되고 있다. 본 논문에서는 초대형 부유식 구조물의 상부구조물에 대한 시간이력해석법에 대하여 소개하고 파랑하중에 의한 부체변형을 이용한 시간변위이력 산정 방법을 제안한다. 또한 주기 및 진폭의 변화에 따른 상부구조물의 동적 시간이력응답 결과를 분석하고 초대형 부유식 상부구조물 시설계안의 동적구조안전성을 평가한다.

• 한국공간구조학회논문집
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• 제4권2호
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• pp.63-71
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• 2004

트러스형 공간 구조물은 무주의 대공간을 덮을 수 있는 장점과 구조적 성질이 동일한 등가 연속체 쉘 로 치환하여도 비교적 정확한 해를 얻을 수 있다는 장점으로 인해 21세기 첨단 구조물의 한 장인 초대형 구조물 분야에 많이 활용되고 있으며, 효율적인 부재의 이용과 대량생산의 가능성으로 인해 많은 발전을 해 왔다. 그러나 이러한 쉘 형태의 공간 구조물은 구조 거동의 특성상 주로 구조안정문제가 구조설계에서 해결해야하는 핵심적인 기술력이 되며, 이를 어떻게 해결하여야 할 것인가의 문제는 아직도 많은 연구자들에게 난제로 남아 있다. 즉, 연속체 쉘 구조의 원리에서 긴 경간을 얇게 만들면, 뜀좌굴과 분기좌굴같은 불안정 거동이 나타나게 되며, 이러한 쉘형 구조 시스템에서 구조 불안정 문제의 특징은 초기 조건에 매우 민감하게 반응한다는 것이고, 이런 문제들은 수학적으로 비선형 문제에 귀착하게 된다. 따라서, 본 논문에서는 공간 프레임형 구조물의 불안정 현상을 살펴보기 위하여, 다양한 파라메타중 초기불완전량과 rise-span 비가 트러스 구조물의 불안정 현상에 미치는 영향을 알아보고자 하며, 이를 위해 1-자유절점 공간구조물, 2-자유절점 공간구조물, 다-자유절점 공간구조물을 예제로 채택하여 불안정 거동을 살펴보고자 한다.

• 한국해양공학회지
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• 제13권4호통권35호
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• pp.19-27
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• 1999

To design a very large floating structure, such as a floating airport, we have to estimate the hydroelastic responses of a very large floating structure (VLFS) exactly. We developed the numerical method for estimating the hydroelastic responses of the VLFS. The developed numerical approach is based on a combination of the three-dimensional source distribution method, the wave interaction theory and the finite element method for structurally treating the space frame elements. The Numerical results of the hydroelastic responses and steady drift forces of a somisubmersible type offshore structure, which is supported by the 33(3 by 11) floating bodies, with various bending rigidities are illustrated.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.1038-1042
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• 2007

The factors influencing the floor impact sound insulation include floor finishing materials, shock absorbing floors (slabs included), and ceiling structures. The ceilings of the apartment houses, currently built in Korea, are set up with lower parts of slabs and paper finishing, or with double floors for protecting against floor impact sounds in order to improve the sound insulating performance. The most common the method of ceiling structure construction consists of 'wood boarded frames + Gypsum boards + ceiling papers', which is called the wood boarded frame method. This study aimed to measures and evaluates floor impact sound insulation by which the ceiling space are widened according to suppression system is added in apartment house ceiling structure.

• 한국실내디자인학회논문집
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• 제15권5호
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• pp.112-119
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• 2006

This study intends to understand the visual experience of architectural space generated by users' movement based on the interpretation of visual properties. An analytic theory of Isovist is suggested for the objective and comparable measurement for such visual experience, and a computer program for the analysis has been proposed as well. By using the analytical theory and computer program, eight houses designed by Adolf Loos and Le Corbusler are analyzed for the purpose of understanding the visual characteristics of the Modern Architecture and the contemporaries. The result shows that, while the architectural space of Loos emphasizes personal privacy as for being livable spaces, the architectural space of Corbusier emphasizes users' movement as for including diverse visual arrays. These commensurable results exhibit that the analytical tool and research frame suggested in this study can be a competitive tool for such analysis.

• Structural Monitoring and Maintenance
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• 제1권4호
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• pp.427-449
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• 2014

A hybrid optimization method for the identification of state-space models is presented in this study. Hybridization is succeeded by combining the advantages of deterministic and stochastic algorithms in a superior scheme that promises faster convergence rate and reliability in the search for the global optimum. The proposed hybrid algorithm is developed by replacing the original stochastic mutation operator of Evolution Strategies (ES) by the Levenberg-Marquardt (LM) quasi-Newton algorithm. This substitution results in a scheme where the entire population cloud is involved in the search for the global optimum, while single individuals are involved in the local search, undertaken by the LM method. The novel hybrid identification framework is assessed through the Monte Carlo analysis of a simulated system and an experimental case study on a shear frame structure. Comparisons to subspace identification, as well as to conventional, self-adaptive ES provide significant indication of superior performance.

• Structural Engineering and Mechanics
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• 제48권1호
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• pp.1-16
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• 2013

The seismic response of RC space frame structures with isolated footing resting on a shallow soil stratum on rock is presented in this paper. Homogeneous soil stratum of different stiffness in the very soft to stiff range is considered. Soil, footing and super structure are considered to be the parts of an integral system. A finite element model of the integrated system is developed and subjected to scaled acceleration time histories recorded during two different real earthquakes. Dynamic analysis is performed using mode superposition method of transient analysis. A parametric study is conducted to investigate the effect of flexibility of soil in the dynamic behaviour of low-rise building frames. The time histories and Fourier spectra of roof displacement, base shear and structural response quantities of the space frame on compliant base are presented and compared with the fixed base condition. Results indicate that the incorporation of soil flexibility is required for the realistic estimate of structural seismic response especially for single storey structures resting on very soft soil.