• Structural Engineering and Mechanics
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• 제18권3호
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• pp.343-362
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• 2004

Rocking response of rigid bodies with rectangular footprint, freely standing on horizontal rigid plane is studied analytically. Bodies are subjected to simulated single component of horizontal earthquakes. The effect of baseline correction, applied to simulated excitations, on the rocking response is first examined. The sensitiveness of rocking motion to the details of earthquakes and geometric properties of rigid bodies is investigated. Due to the demonstrated sensitivity of rocking response to these factors, prediction of rocking stability must be made in the framework of probability theory. Therefore, using a large number of simulated earthquakes, the effects of duration and shape of intensity function of simulated earthquakes on overturning probability of rigid bodies are studied. In the case when a rigid body is placed on any floor of a building, the corresponding probability is compared to that of a body placed on the ground. For this purpose, several shear frames are employed. Finally, the viability of the energy balance equation, which was introduced by Housner in 1963 and widely used by nuclear power industry to estimate the rocking stability of bodies, is evaluated. It is found that the equation is robust. Examples are also given to show how this equation can be used.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2015년도 추계 학술논문 발표대회
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• pp.164-165
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• 2015

Modular construction technique is an adaptation of factory-based mass production concept in ordinary manufacturing industries to construction industry and it assumes that panels, units, etc. are fabricated in factories and assembled in construction sites. Given its structural limitations, modular construction technique is primarily used in low-story buildings whose maximum height is usually five stories, but researchers are actively studying possible adaptation of modular construction technique to high-rise building designs these days as in the case of infill-type modular construction design. Infill-type modular construction technique, most frequently used in high-rise building construction projects, completes frame construction first in reinforced concrete structures and fills unit modules in such structures. However, infill-type modular construction technique leads to longer construction schedule accompanying increase in construction cost, cost overrun due to additional of temporary work, and possible damage to units in the wake of facility construction. Accordingly, this study is performed as a basic study for the development of bottom-up infill-type modular construction technique intended to construct structural frames and fill in units sequentially in a bid to address such drawbacks of current infill-type modular construction technique.

• 한국정밀공학회지
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• 제34권3호
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• pp.217-224
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• 2017

Structural pipe frames are usually manufactured by complex processes, in which a straight pipe with an arbitrary cross-section is prepared via a roll-forming process and then fabricated into three-dimensional shapes by a secondary process. These conventional processes have low productivity. Recently, the inefficiency of the conventional processes has created the need to develop new forming technologies. In this study, a new incremental roll-forming process is proposed. The study is aimed at verifying the feasibility of the proposed process and investigating the fundamental process parameters using finite-element simulations. The result of the simulation demonstrates that the proposed process can be used effectively for cold fabrication of various shapes of structural pipes. In addition, the result of the investigation of parameters shows that the forming amount, number of roll sets, and distance between roll sets are significant factors to be considered in resolving dimensional errors of the product and improving its quality.

• 한국해양공학회지
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• 제22권5호
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• pp.132-137
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• 2008

Ship structures are subject to severe environmental loads causing appreciable hull girder bending which in turn affects the piping system attached to the main hull in the form of a displacement load. While this load may cause failure in the pipes, loops have been widely adopted as a means of preventing this failure, with the idea that they may lower the stress level in a pipe by absorbing some portion of the displacement load. But since such loops also have some negative effects, such as causing extra manufacturing cost, deteriorating the function of the pipe, and occupying extra space, the number and dimensions of the loops adopted need to be minimized. This research developed design formulas for pipe loops, modeling them as frames composed of beam elements, where not only bending but also shear deflection is taken into account. The accuracy of the proposed design formulas was verified by comparing two results respectively obtained by the proposed formulas and MSC/NASTRAN. The paper concludes with a sample example showing the efficiency of the proposed formulas.

• 한국컴퓨터산업학회논문지
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• 제6권5호
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• pp.801-812
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• 2005

H.264/AVC는 부호화 효율을 크게 향상시킨 비디오 부호화에 대한 표준이다. ITU-T와 MPEG는 가변블록의 움직임, 다중참조화면, l/4 화소 움직임 추정/보상기법과 비트율-왜곡 최적화 기법 등 다양하고 복잡한 부호화 기법들을 적용했다. H.264 참조 모델은 비트율-왜곡 최적화 기법에 기반을 둔 복잡한 부호화 모드 결정 기법을 채택했는데, 이는 부호화기의 높은 복잡성을 요구한다. 본 논문에서는 매크로 블록 부호화 모드의 순서에 대한 비트율-왜곡의 비용 값의 분포에 기초한 효율적인 부호화 모드 결정 기법을 제안하였다. 실험결과는 제안한 방법이 부호화 시간에 있어 34%를 감소시켰으며, 비트율-왜곡의 계산 량을 82% 줄였음을 보여준다.

• 한국컴퓨터산업학회논문지
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• 제2권11호
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• pp.1421-1426
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• 2001

오늘날 멀티미디어 정보의 양이 매우 빠른 속도로 증가함에 따라 멀티미디어에 대한 효율적인 관리가 더욱 중요하게 되었다. 특히 동영상과 같은 이미지에서는 특정 이미지를 추출하여 필요한 이미지를 관리하고자 하는 욕구가 증가되어가고 있다. 본 논문에서는 멀티미디어 자료의 효과적인 색인화 및 검색을 위한 동영상 처리를 위한 여러 멀티미디어 의미정보 추출 방법 중 내용 기반 의미 정보 추출 방법을 이용하여 특정 이미지를 검색하고 추출된 이미지만 저장하는 알고리즘을 설계하였다. 입력 영상에서 RGB 정보를 추출한 후 동영상의 모든 프레임을 순차적으로 검사하면서 주 RGB 범위 군집화 방법을 통하여 구성 내용의 위치와 분포를 참조하여 일치여부를 파악하여 입력 영상과 일치하는 동영상을 저장하도록 하였다.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
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• pp.471-474
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• 2006

The Mixer is apparatus that help precipitation or an inhomogeneous distribution of various phases to be mixed and that user makes necessary material mixing one or the other. Mainly the mixer which is used from chemical and food industry is very important system in engineering that mixes the material. The inside flow of the mixer under the actual states which put a basis in flow of the fluid is formed rotation of the impeller. The inside flow of impeller will be caused by various reasons change with shape of impeller, number of rotation, mixing material and flow pattern of free surface etc. Also mixer study depended in single-phase flow and experimental research. So the numerical analysis of flow mixing solid-fluid particle is simulated. It is become known, that the case where agitator inside working fluid includes the solid particle the sinkage reverse which the solid particle has decreases an agitation efficiency. From the research which it sees the hazard solid which examines the effect where the change of the sinkage territory which it follows agitation number of revolution and diameter of the particle goes mad to an agitator inside flow distribution - numerical analysis the inside flow distribution of liquid state with Eulerian Two-Phase Method.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.852-855
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• 2003

Gas-Assisted Injection Molding(GAIM) process, that can be used to provide a hollow shape in a molding, is a variant of the conventional injection molding process. GAIM has many advantages such as reduction of material, sink mark. warpage. and lower injection pressure. Thus, GAIM has been widely applied in the industry to make moldings with a hollow channel such as handles, TV frames and so on. On the other hand, GAIM has some disadvantages such as slow cooling time and flow marks. In the disadvantages, hot gas core causes slow cooling of a molding and the overflow. which is to prevent flow mark. is waste of materials. To solve these problems, we developed a new GAIM system that we called RGIM(Reverse Gas Injection Molding). The RGIM has two special units; one is the overflow buffer, which is used for reduction of a material, and the other tile air unit, which is used for faster cooling of a molding. We conducted an experiment and simulation to verify the efficiency of the RGIM system. Through experiments and simulation, we confirmed the effectively operating of the RGIM system and extracted the optimum process conditions.

• 한국생산제조학회지
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• 제21권5호
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• pp.797-804
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• 2012

Magnesium has a long tradition of use as a lightweight material in the field of automotive industry. This paper presents the design optimization process of Mg armrest frame to minimize its weight by replacing the steel frame. formerly, the analysis of steel armrest frame was peformed to determine the design specifications for Mg armrest frame. The initial design of Mg armrest frame was carried out by topological optimization technique. After six types of design variables and four types of response variables were defined, DOE(Design of Experiment) and RSM (Response Surface Method) were applied in order to measure sensitivity of design variables and realize optimization through regression model. After design optimization, the weight of the optimized Mg armrest frame was reduced by about 3% compared to the initial design of the Mg frame and was decreased by 41.7% in comparison with that of the steel frame. Some prototypical armrest frames were also made by die casting process and tested. The results were satisfying for its design specifications.

• Earthquakes and Structures
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• 제18권3호
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• pp.391-405
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• 2020

The use of passive energy dissipation devices has been widely used in the construction industry to minimize the probability of damage occurred under intense ground motion. In this study, collapse margin ratio (CMR) and fragility curves are the main parameters in the assessment to characterize the collapse safety of the structures. The assessment is done on three types of RC frame structures, incorporating three types of dampers, viscoelastic, friction, and BRB dampers. The Incremental dynamic analyses (IDA) were performed by simulating an array of 20 strong ground motion (SGM) records considering both far-field and near-field seismic scenarios that were followed by fragility curves. With respect to far-field ground motion records, the CMR values of the selected frames indicate to be higher and reachable to safety margin more than those under near-field ground motion records that introduce a high devastating impact on the structures compared to far-field excitations. This implies that the near field impact affects the ground movements at the site by attenuation the direction and causing high-frequency filtration. Besides that, the results show that the viscoelastic damper gives better performance for the structures in terms of reducing the damages compared to the other energy dissipation devices during earthquakes.