• 한국건축시공학회지
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• 제14권6호
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• pp.571-581
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• 2014

본 연구에서는 중공 PC 벽체 (PC Double Wall)를 적용한 계단실 공법을 개발하였다. 중공 PC 벽체는 내부 중공으로 인하여 양중 무게를 줄이고 외부 벽체가 거푸집 역할을 하며, 벽체 내부 중공에 현장 콘크리트를 타설하여 기존 PC 벽체와 비교하여 부재간의 일체성 확보가 우수하다. PC Double Wall 제작 및 현장 콘크리트 타설, 구조적 안전성을 고려하여 PC 벽체 단면과 철근 배근 상세를 제안하였다. 제안 상세를 바탕으로 얇은 PC벽체와 중공부를 효과적으로 형성하기 위한 세움 타설 방식의 거푸집 시스템을 개발하였다. PC Double Wall을 이용하여 계단실 Mock-up test를 통하여 부재 간 일체성과 시공성을 검증하였으며, 부재 간 접합부의 변형 및 균열이 발생하지 않고 시공성이 우수한 것으로 나타났다.

• 대한치과보철학회지
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• 제44권1호
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• pp.10-19
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• 2006

Statement of problem : The various kinds of properties of post and core may affect the stress distribution to the root of endodontically treated teeth Purpose: To evaluate the influence of various kinds of properties of post and core to the stress distribution to the root of endodontically treated teeth. Material and methods: Mandibular first premolar, prepared by general shape of post and core with gold crown, was used to two dimensional axisymmetric modeling for finite element analysis. Then property values of 8 different kinds of post and core was substituted for each. Finally, stress distribution shown areas around the root of post and core was analysed after applying 50N of vortical and oblique load. Results: 1. Stress value of oblique load was much higher than the maximum stress value of vertical load. 2. Under oblique load, very concentrated stress was located on post periapical area and variations in stress were very severe. Contrary to this, stress distribution was relatively uniform in vertical load. 3. Post materials with higher elastic modulus showed relatively more apically focused stress, and post materials with lower elastic modulus showed stress focused on cervical area on the axial wall of post. 4. Stress change according to the properties of core was shown only in the cervical area of post and below core as the higher elastic modulus, then increased in stress. 5. Post and core with medium value of elastic modulus showed relatively uniform stress distribution. Conclusions: Post materials with higher elastic modulus showed relatively more apically focused stress, and post materials with lower elastic modulus showed stress focused on cervical area on the axial wall of post. Stress change according to the properties of core was shown only in the cervical area of post and below core.

• Applied Biological Chemistry
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• 제34권2호
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• pp.110-116
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• 1991

Wall 물질로 저분자량 polyethylene(LMPE)과 urea-formaldehyde 수지를 이용하여 일반적 인 저분자 페로몬과 유사한 특성과 구조를 갖는 모델 화합물로서 citral, n-octanol, 그리고 쌀바구미, 옥수수바구미의 집합 페로몬 활성을 갖는 $({\pm})-5-hydroxy-4-methyl-heptan-3-one$을 microencapsulation하였다. Microencapsulation된 형태는 작은 입자형태의 분말상이었으며, LMPE를 wall물질로 사용한 것 보다는 urea-formaldehyde수지를 사용한 경우가 더 우수한 형태의 polymer를 얻었다. 또한 core 물질의 slow release 효과를 용매 추출법과 headspace 방법으로 측정한 결과 n-octanol과 citral은 40일 이상 그리고 5-hydroxy-4-methyl-heptan-3-one은 15일 이상 지속 효과를 보였다. 그리고 slow release되는 방식은 LMPE보다 urea-formal-dehyde 수지가 상대적으로 초기 감소 경향이 완만하며 core 물질을 일정양씩 더 지속적으로 휘발시켰다.

• Nuclear Engineering and Technology
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• 제47권4호
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• pp.416-423
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• 2015

It had been disputed how to apply wall drag to the dispersed phase in the framework of the conventional two-fluid model for two-phase flows. Recently, Kim et al. [1] introduced the volume-averaged momentum equation based on the equation of a solid/fluid particle motion. They showed theoretically that for dispersed two-phase flows, the overall two-phase pressure drop by wall friction must be apportioned to each phase, in proportion to each phase fraction. In this study, the validity of the proposed wall drag model is demonstrated though one-dimensional (1D) simulations. In addition, it is shown that the existing form loss model incorrectly predicts the motion of the dispersed phase. A new form loss model is proposed to overcome that problem. The newly proposed form loss model is tested in the region covering the lower plenum and the core in a nuclear power plant. As a result, it is shown that the new models can correctly predict the relative velocity of the dispersed phase to the surrounding fluid velocity in the core with spacer grids.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2003년도 춘계 학술발표회논문집
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• pp.329-336
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• 2003

The box system that is composed only of reinforced concrete walls and slabs are adopted on many high-rise apartment buildings recently constructed in Korea. And the framed structure with shear wall core that can effectively resist horizontal forces is frequently adopted for the structural system for high-rise building structures. In these structures, a shear wall may have one or more openings for functional reasons. It is necessary to use subdivided finite elements for accurate analysis of the shear wall with openings. But it would take significant amount of computational time and memory if the entire building structure is subdivided into a finer mesh. An efficient analysis method that can be used regardless of the number, size and location of openings is proposed in this study. The analysis method uses super element, substructure, matrix condensation technique and fictitious beam technique. Three-dimensional analyses of the box system and the framed structure with shear wall core having various types of openings were peformed to verify the efficiency of the proposed method. It was confirmed that the proposed method have outstanding accuracy with drastically reduced time and computer memory from the analyses of example structures.

• Steel and Composite Structures
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• 제35권2호
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• pp.159-169
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• 2020

Sandwich composite wall consists of concrete core attached by two external steel faceplates. It combines the advantage of steel and concrete. The appropriate composite action between steel faceplate and concrete core is achieved by using adequate mechanical connectors. This research studied the compressive behavior of the sandwich composite walls using steel trusses to bond the steel faceplates to concrete infill. Four short specimens with different wall width and thickness of steel faceplate were designed and tested under axial compression. The test results were comprehensively evaluated in terms of failure modes, load versus axial and lateral deformation responses, resistance, stiffness, ductility, strength index, and strain distribution. The test results showed that all specimens exhibited high resistance and good ductility. Truss connectors offer better restraint to walls with thinner faceplates and smaller wall width. In addition, increasing faceplate thickness is more effective in improving the ultimate resistance and axial stiffness of the wall.

• 대한건축학회논문집:구조계
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• 제35권10호
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• pp.155-162
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• 2019

Hybrid precast concrete panel is a wall element that is able to quickly construct the core wall structure for moderate-rise modular buildings. Hybrid precast concrete panel has unique characteristics which is a pair of C-shaped steel beams combined at the top and bottom of a concrete wall, In this study, an improved anchorage detail for vertical rebar is proposed to ensure the lateral force resistance performance of hybrid precast concrete panel emulating monolithic concrete wall. Also, the structural performance of horizontal connection is investigated experimentally with the bolt spacing parameter. And the behavior of hybrid precast concrete panel with the improved detail is compared with the monolithic concrete wall tested in a previous study. Finally, the required thickness of C-shaped steel beam to eliminate or minimize the deformation in horizontal connection is calculated by prying action equation.

• 한국구조물진단유지관리공학회 논문집
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• 제23권5호
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• pp.37-47
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• 2019

본 논문은 바닥 격막을 고려한 코어 및 오프셋 아웃리거 구조의 최적위치를 파악하기 위하여 70층 규모의 초고층 아웃리거 건물을 대상으로 MIDAS-Gen을 이용하여 구조설계를 실시하였다. 그리고 본 해석연구의 주요 변수는 슬래브의 강성, 전단벽의 강성, 아웃리거의 평면상 위치이다. 또한 본 해석결과에 근거하여 슬래브의 강성과 전단벽의 강성이 바닥 격막을 고려한 코어 및 오프셋 아웃리거 구조의 최적 위치에 미치는 영향을 분석하였다. 본 해석연구의 결과에서는 슬래브의 강성, 전단벽의 강성, 아웃리거의 평면상 위치가 초고층 아웃리거 구조시스템의 최적위치에 어떤 영향을 주는 지를 분석하여 나타났다. 그리고 본 논문의 결과는 초고층 아웃리거 구조시스템의 최적위치를 조사하는데 필요한 구조공학자료를 얻는데 도움이 된다고 사료된다.

• 한국건축시공학회지
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• 제7권4호
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• pp.153-159
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• 2007

Recently, as a result of the economic growth, the concentration of population towards the cities and the rise in land prices, the demand for high rise buildings has increased significantly, the trend to build high rise buildings such as the mixed-use development buildings by the domestic construction companies continues. It's very important what kind of form work system is applied on the Core Wall of the high rise buildings to determine the economic efficiency for the whole project. That's because the appropriate selection of the Formwork system enables the construction cost lower, makes the good quality of the finished concrete, reduces the construction period, assurance of safety, and further more, it enables to achieve the successful performance of the projects. Therefore, this research, after comparing the strength and the weakness between the construction methods, focus the point to provide a builder the basic data to choose the right Formwork method.

• Earthquakes and Structures
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• 제20권2호
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• pp.175-185
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• 2021

This study strives to highlight the importance of considering the vertical ground motions (VGM) in the seismic evaluation of RC buildings. To this aim, IDA (Incremental Dynamic Analysis) is conducted on three code-based designed high-rise RC frame-core wall buildings using a suite of earthquake records comprising of significant VGMs. To unravel the significance of the VGM inclusion on the performance of the buildings, IDAs are conducted in two states (with and without the vertical component), and subsequently based on each analysis, fragility curves are developed. Non-simulated collapse criteria are used to determine the collapse state drift ratio and the area under the velocity spectrum (SIm) is taken into account as the intensity measure. The outcome of this study delineates that the inclusion of VGM leads to the increase in the collapse vulnerability of the structures as well as to the change in the pattern of inter-story drifts and failure mode of the buildings. The results suggested that it would be more conservative if the VGM is included in the seismic assessment and the fragility analysis of RC buildings.