• 국제학술발표논문집
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• The 10th International Conference on Construction Engineering and Project Management
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• pp.85-92
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• 2024

Reinforced concrete modular integrated construction (MiC) has been widely used in Hong Kong nowadays, but the solutions for temporary tying of the side walls during the construction of the composite wall have still shortcomings. Based on a MiC project in Hong Kong, this paper proposes a new inner tie system for composite wall. The system components are installed on the side walls of precast modules without penetrating through the side walls. After the loop is rotated to contact the hook, the tying effect can be generated when the concrete is poured on site between the middle gap of two modules. This system replaces tie bolts penetrating through precast side walls, so that the modules' interior fitting-out can be fully completed in factory and the on-site construction has no adverse effects on the internal decoration. This paper mainly describes the mechanism of the system, FEA simulation and optimization of the member size, as well as tensile and punching shear tests to verify the reliability, safety and to get more information about failure mode of the system. The system will be further examined by assembling 1:1 mockup modules, and finally applied to a real MiC project soon. The system can also act as permanent tie bars for the composite wall to reduce the total wall thickness, save the structural cost and increase the usable area. Compared with other existing tying methods in the industry, the system is easy to install, reliable to take loads, adaptable to large construction errors, and has the potential to be widely used in future practical projects.

• Steel and Composite Structures
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• 제32권3호
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• pp.337-346
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• 2019

The present paper tries to contribute fill the gap of application of the component method to tubular connections. For this purpose, one typical joint configuration in which just one component can be considered as active has been studied. These joints were selected as symmetrically loaded welded connections in which the beam width was the same as the column width. This focused the study on the component 'side walls of rectangular hollow sections (RHS) in tension/compression'. It should be one of the main components to be considered in welded unstiffened joints between I beams and RHS columns. Many experimental tests on double-sided I-beam-to-RHS-column joint with a width ratio 1 have been carried out by the authors and a finite element (FE) model was validated with their results. Then, some different analytical approaches for the component stiffness and strength have been assessed. Finally, the stiffness proposals have been compared with some FE simulations on I-beam-to-RHS-column joints. This work finally proposes the most adequate equations that were found for the stiffness and strength characterization of the component 'side walls of RHS in tension/compression' to be applied in a further unified global proposal for the application of the component method to RHS.

• The Journal of the Acoustical Society of Korea
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• 제28권2E호
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• pp.60-65
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• 2009

The present study aims to investigate the effects of sound diffusers and absorbers on the sound clarity in classrooms. In order to do this, computer simulations were carried out to find the effective area of treatment which could enhance the sound clarity in the room. Acoustic measurements were undertaken in a lecture room with several conditions changing the surface of walls and ceilings with diffusers and absorbers. Diffusion and absorption treatments were applied to the side walls, rear wall and the ceiling of the classroom. SPL, RT, D50, RASTI were measured at 9 measurement points with one sound source and MLS was used as the sound source signal. The results show that higher sound clarity was obtained when diffusers were applied to rear walls and ceiling rather than side walls. Also, it was confirmed that absorption increased sound clarity more effectively with smaller amount in comparison with diffusers. It was also concluded that the effects of sound diffusers and absorbers on the sound clarity could be obtained distinctly at the rear area of the classroom.

• 대한기계학회논문집A
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• 제37권10호
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• pp.1269-1278
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• 2013

엔드밀링 공정은 형상창성기구의 특성 상, 절삭면적의 주기적인 변화를 피할 수 없다. 그러므로, 본 연구에서는, 가공 중 절삭날과 공작물 사이의 간섭영역에 해당하는 절삭면적의 모델을 확립하여, 가공면 형상 특성과 절삭면적의 관계를 규명하고자 한다. 대상 가공면은 측벽을 선정하였으며, 형상 특성은 축 방향 진직도를 선택하였다. 절삭면적 및 축방향 진직도에 영향을 미치는 특이점 추정 모델의 타당성은 반경 방향 및 축 방향 절삭깊이를 변화시키며 엔드밀링 가공을 수행하여 검증하였다. 연구 결과, 배분력이 음의 값을 갖지 않는 안정적인 엔드밀링 가공의 경우, 상향절삭은 절삭면적이 증가했다. 일정해지는 영역에서, 하향절삭은 절삭면적이 일정했다 감소하는 영역에서 가공면을 창성하며, 영역이 변화될 때 가공면에 특이점이 발생하는 것이 확인되었다.

• Earthquakes and Structures
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• 제23권2호
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• pp.151-168
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• 2022

Torsion is one of the most important causes of building collapse during earthquakes. Sometimes, despite the symmetric form of the building, infill walls disturb the symmetry of the lateral resisting system. The purpose of this research is to investigate the effect of urban layout on developing torsion caused by infill walls. For this purpose, a typological study was conducted based on the conditions of perimeter walls on 364 buildings and then 9 cases were selected. The dimensions of the selected buildings are constant and the conditions of the perimeter walls including facades with openings and cantilevered facades are variable. The selected buildings with 60 different layouts of infill walls were analyzed and the behavior of each one was evaluated based on the torsional irregularity criteria of seismic codes. The results of the analyses showed that if the perimeter walls of a building are symmetric, asymmetric interior walls will not be important in developing torsion and effective parameters in symmetry of the perimeter infill walls are the number of walls, area of openings, aspect ratio, and construction details. Finally, architectural solutions to mitigate the torsional effects of infill walls were proposed for buildings with solid infill walls on some sides, for buildings where the perimeter walls of one side are on the cantilevered part, and for buildings where the perimeter walls of two adjacent sides are on the cantilevered part. In three-sided buildings, where two adjacent façades are cantilevered, it is often impossible to use the potential of the infill walls.

• 한국디지털건축인테리어학회논문집
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• 제8권2호
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• pp.57-64
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• 2008

The walls of art museums become the background of exhibits, and they form a unit space depending on the of each exhibit. In addition, the walls are configured and presented depending on the rhythm of space, or the structure of an axis. In this study, according to the axis composed for each unit space, the presentation methods of walls were classified as follows: The central type, the skewed type, the crossed type, the one-side corridor type, and the two-way corridor type. By analyzing visual configurations formed by the arrangement of each unit space, the value and the hierarchy of walls are discussed To analyze the classified types with the physical change of unit space, the factors of visual integration, connectivity, depth, and visual axis are compared, and various configurations of walls and space change are applied.

• Computers and Concrete
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• 제19권5호
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• pp.509-514
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• 2017

Concrete retaining walls are the most common types of geotechnical structures for controlling instable slopes resulting from lateral pressure. In analytical stability, calculation of the concrete retaining walls is regarded as a rigid mass when its safety is required. When cracks in these structures are created, the stability may be enforced and causes to defeat. Therefore, identification, creation and propagation of cracks are among the important steps in control of lacks and stabilization. Using the numerical methods for simulation of crack propagation in concrete retaining walls bodies are among the new aspects of geotechnical analysis. Among the considered analytical methods in geotechnical appraisal, the boundary element method (BEM) for simulation of crack propagation in concrete retaining walls is very convenient. Considered concrete retaining wall of this paper is Pars Power Plant structured in south side in Assalouyeh, SW of Iran. This wall's type is RW6 with 11 m height and 440 m length and endurance of refinery construction lateral forces. To evaluate displacement and stress distributions (${\sigma}_{1,max}/{\sigma}_{3,min}$), the surrounding, especially in tip and its opening crack BEM, is considered an appropriate method. By considering the result of this study, with accurate simulation of crack propagation, it is possible to determine the final status of progressive failure in concrete retaining walls and anticipate the suitable stabilization method.

• Journal of Plant Biology
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• 제36권3호
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• pp.285-292
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• 1993

Cellular compatibility in the self-parasitism of Cuscuta australis R. Brown was studied at the ultrastructural level. The front cells of the haustorium penetrated the host stems independently grew within the host tissues and transformed into elongate, filamentous hyphae. Each hyphal cells contained a large nucleus and dense cytoplasm with abundant cell organelles. Multilamellar structures were contained in the cytoplasm and cell walls of the penetrating hyphal cells. When the hyphal cells did not yet invade the host cells, the middle lamella and the fused cellulosic cell walls of the two partners at the host-parasite interface were preserved well. As the invasion of the parasitic hyphal cells progressed, however, the middle lamella was not found at the interface and the host cell walls and plasma membranes were partially broken down. A hyphal cell penetrated deeply into the host cell had a more darkly stained cytoplasm with numerous of cell organelles. In the host cells attacked by the hyphal cells the limiting membranes of plastids were broken down and several vesicles were arrayed near the cell walls. No plasmodesmatal connections between the host and parasite cell walls were found; however, half-plasmodesmata were observed frequently on the side of the hyphal cell walls. These results suggested that the compatibility response in the self-parasitism of Cuscuta was expressed by cell walls, not by plasmodesmata, between the host and the parasite cells.

• 한국조경학회지
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• 제30권2호
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• pp.63-69
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• 2002

The Second Namsan Tunnel required renovation. The landscape design was conducted as part of the comprehensive programs for renovation. The landscape design covered site analysis, design development, a working drawing and a maintenance plan. In May of 2001, the Second Namsan Tunnel was renovated and reopened to traffic. The tunnel was recreated as a new type of tunnel with function and beauty. The entrance and retaining wall of the tunnel has public character. Users are greatly affected by the entrance and retaining walls along roads. The landscape architect had to find new materials and methods to improve the environment and to combine artwork with the entrance and walls of the tunnel. The surface of the tunnel entrance and retaining walls are artistically treated with ceramic tiles and paint. Various regional characteristics and cultural meaning are symbolically expressed. Or the tunnel entrance from the Joong-gu side, entitled "Glory of the Future", the hibiscus symbolizes the bright and glorious future of Korea. On the retaining walls, entitled "Hope", the promising Joong-gu is symbolized through image of Korean magpies, mountains, rocks, roses, winds and nature. As for the tunnel entrance from the Yongsan-gu side, entitled "Vivid Spirit", pine trees symbolize the Koreans′strong will and an enterprising spirit. On the retaining walls, entitled "Lively Motions", Yongsan-gu is symbolized through image of pigeons, mountains, rocks, roses, winds and clear skys. The entrance and retaining wall of the Second Namsan Tunnel, whose surfaces are treated with tiles and paint with artistic value, would create an atmosphere using large-scale wall paintings. In this artwork, users would perceive a unique sense of place through the symbolic images of the vertical planes of the tunnel.

• Wind and Structures
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• 제13권1호
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• pp.83-94
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• 2010

Wind tunnel measurements on T-shaped free-standing walls and inclined free-standing walls have been carried out. Mean net pressure coefficients have been derived and compared with previous research. It was observed that the high loads at the free ends are differently distributed than those derived from the pressure coefficients for free-standing walls in EN 1991-1-4. In addition net pressure coefficients based on extreme value analysis have been obtained. The lack of correlation of the wind induced pressures at windward and leeward side result in lower values for the net pressure coefficients when based on extreme value analysis. The results of this wind tunnel study have been included in Dutch guidelines for noise barriers.