• 대한건축학회논문집:계획계
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• 제35권11호
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• pp.13-24
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• 2019

The history of tall buildings begins in 1853with the development of elevators. After the Industrial Revolution of the 18th century, the development of high-rise buildings will be carried out in earnest as a means to efficiently use the limited land of cities. The development, which began around Chicago, extended over a long period of time to Asia, maximizing the high competition. However, in the 2000s, not only was it high due to the development of construction and digital technology, but it also became competitive in eco-friendly elements and unstructured forms. High-rise building plans that have gained elemental and morphological diversity are completed by the interrelationships of various plans. Among them, it is important that the core plan has a reasonable approach from the initial planning stage as the basis for the vertical copper plan linking vertically-intensive functions. The cores should be designed to be clear and adequately responsive to changes in the shape of the building. This study aims to provide designers with a reasonable understanding of core planning by identifying core characteristics of irregular high-rise. In particular, we want to analyze the shape of the ground layer core and the relationship between the area and components of the ground layer core. The analysis results are as follows, classified according to the type or use of the building. Of the atypical forms composed of double bending, the TAPER-Curve and TWIST forms are the most distributed, and the plane and core shapes of the ground floor are the most commonly used. Based on the analysis of the validity of the ground floor cores by shape of the cores, the most commonly used forms for core shapes in the planning of the atypical high-rise are square, circular and Oval, and the most efficient oval cores and relatively inefficient ones when planned.

• Applied Biological Chemistry
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• 제46권4호
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• pp.305-310
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• 2003

Hydrophobic core가 변이된 유비퀴틴 단백질이 pH 2 용액에서 보이는 구조적인 특성을 여러 분광학적 방법으로 측정하였다. 낮은 pH값을 갖는 용액에서 이 변이 유비퀴틴의 intrinsic tryptophan fluorescence emission spectrum은 unfolded 상태보다 약간 blue shift되어 있고 또한 그 intensity도 상당히 낮게 나타났다. 이는 이 용액 조건에서 이 변이 유비퀴틴의 삼차구조가 약간 남아 있는 것을 의미한다. 같은 용액에서 이 변이 유비쥐틴의 far-UV circular dichroic spectrum은 native 상태나 unfolded 상태의 spectrum과 현저히 달랐으며 220 nm 에서의 molar ellipticity 값을 통하여 볼 때 pH 2인 용액에서 상당량의 이차구조를 지니고 있었다. 또한 같은 용액에서 이 변이 유비퀴틴은 hydrophobic dye인 8-anilinonaphthalene-1-sulfonic acid(ANS)외 fluorescence emission intensity를 증가시키고 fluorescence emission maximum이 짧은 파장에서 나타나게 하였다(blue shift). 이러한 현상은 pH 2 용액에서 이 변이 유비퀴틴의 hydrophobic core가 느슨하여져서 hydrophobic dye인 ANS가 결합할 수 있는 구조를 띠고 있음을 나타낸다. 이러한 분광학적인 관찰은 이 변이 유비귀틴이 pH 2인 용액에서 상당량의 이차구조를 지니고 있지만 hydrophobic core는 느슨하게 형성된 molten globule과 같은 형태를 지니고 있음을 나타낸다. 이 변이 유비퀴틴의 molten 히obule 형태는 단백질 폴딩 반응의 경로를 연구할 수 있는 좋은 모델이 될 수 있을 것으로 생각된다.

• 한국전산유체공학회지
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• 제10권4호통권31호
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• pp.66-71
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• 2005

HANARO, a multi-purpose research reactor, 30 MWth open-tank-in-pool type, is planning to produce a fission moly-99 of radio isotopes, a mother nuclide of Tc-99m, a medical isotope and a target handling tool is under development for loading and unloading it in a circular flow tube (OR-5) of HANARO. A guide tube is extended from the reactor core to the top of the reactor chimney for easily loading the target under a normal operation of the reactor. But active coolant through the core can be quickly raised up to the top of the chimney through the guide tube. The jet flow was suppressed in the guide tube after reducing the inner diameter of a flow restriction orifice installed in the OR-5 flow tube for adding the pressure difference in the flow tube. This paper describes an analytical analysis to calculate the flow distribution in the core of HANARO after suppressing the jet flow of the guide tube. As results, it was confirmed through the analysis results that the flow distribution in the core of HANARO were not adversely affected.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2005년도 춘계 학술대회논문집
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• pp.70-73
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• 2005

The HANARO, multi-purpose research reactor, 30 MWth open-tank-in-pool type, is planning to produce a fission moly-99 of radio isotopes, a mother nuclide of Tc-99m, a medical isotope and is under developing a target handling tool for loading and unloading it in a circular flow tube (OR-5). A guide tube is extended from the reactor core to the top of the reactor chimney for easily loading the target under the reactor normal operation. But active coolant through the core can be quickly raised up to the top of the chimney through the guide tube. The jet flow was suppressed in the guide tube after reducing the inner diameter of a flow restriction orifice installed in the OR-5 flow tube for adding the pressure difference in the flow tube after unloading the target. This paper describes an analytical analysis to calculate the flow distribution in the core of the HANARO after suppressing the jet flow of the guide tube. As results, it was confirmed through the analysis results that the flow distribution in the core of the HANARO were not adversely affected.

• 한국공간구조학회논문집
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• 제6권1호
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• pp.55-63
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• 2006

본 논문은 콘크리트 충전 원형 및 각형 합성 강관을 기둥부재로서의 적합성 및 적용성을 위한 연구로 두개의 강관을 합성한 콘크리트 충전 강관 기둥의 축압축 좌굴내력 및 변형형상에 대한 실험적 연구이다. 강관 기둥에 대한 연구는 콘크리트 충전 원형 강관 기둥, 콘크리트 충전 각형 강관 기둥, 콘크리트 충전 합성 강관 기둥으로 분류하여 실험을 수행하였다.

• Steel and Composite Structures
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• 제42권5호
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• pp.617-631
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• 2022

To study the eccentric compressive performance of the basalt-fiber reinforced recycled aggregate concrete (BFRRAC)-filled circular steel tubular stub column, 8 specimens with different replacement ratios of recycled coarse aggregate (RCA), basalt fiber (BF) dosage, strength grade of recycled aggregate concrete (RAC) and eccentricity were tested under eccentric static loading. The failure mode of the specimens was observed, and the relationship curves during the entire loading process were obtained. Further, the load-lateral displacement curve was simulated and verified. The influence of the different parameters on the peak bearing capacity of the specimens was analyzed, and the finite element analysis model was established under eccentric compression. Further, the design-calculation method of the eccentric bearing capacity for the specimens was suggested. It was observed that the strength failure is the ultimate point during the eccentric compression of the BFRRAC-filled circular steel tubular stub column. The shape of the load-lateral deflection curves of all specimens was similar. After the peak load was reached, the lateral deflection in the column was rapidly increased. The peak bearing capacity decreased on enhancing the replacement ratio or eccentric distance, while the core RAC strength exhibited the opposite behavior. The ultimate bearing capacity of the BFRRAC-filled circular steel tubular stub column under eccentric compression calculated based on the limit analysis theory was in good agreement with the experimental values. Further, the finite element model of the eccentric compression of the BFRRAC-filled circular steel tubular stub column could effectively analyze the eccentric mechanical properties.

• Steel and Composite Structures
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• 제22권4호
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• pp.821-835
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• 2016

The paper presents an experimental study of the structural behavior of circular flyash-concrete-filled steel tubular stub columns under axial compressive loads. In this study, 90% and 100% by weight of the cement in the concrete core was replaced with flyash. Twenty-seven specimens were tested to study the influence of flyash content, wall thickness of the steel tube, and curing age on the ultimate capacity and confinement effect. The experimental results were compared with the design values calculated using AISC-LRFD (1999), ACI (1999), AIJ (1997) and Eurocode 4 (1994). From the experimental study, it was determined that the confinement effect of circular steel tubes filled with high content flyash concrete was better than that of specimens filled with ordinary Portland cement concrete. The 5.88-mm-thick steel tube filled with 100% flyash concrete was equivalent in strength to a steel tube filled with C30 concrete at 28 days.

• Steel and Composite Structures
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• 제18권3호
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• pp.739-756
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• 2015

This paper presents investigations on the hysteretic behavior of concrete-filled circular tubular (CFCT) T-joints subjected to axial cyclic loading at brace end. In the experimental study, four specimens are fabricated and tested. The chord members of the tested specimens are filled with concrete along their full length and the braces are hollow section. Failure modes and load-displacement hysteretic curves of all the specimens obtained from experimental tests are given and discussed. Some indicators, in terms of stiffness deterioration, strength deterioration, ductility and energy dissipation, are analyzed to assess the seismic performance of CFCT joints. Test results indicate that the failures are primarily caused by crack cutting through the chord wall, convex deformation on the chord surface near brace/chord intersection and crushing of the core concrete. Hysteretic curves of all the specimens are plump, and no obvious pinching phenomenon is found. The energy dissipation result shows that the inelastic deformation is the main energy dissipation mechanism. It is also found from experimental results that the CFCT joints show clear and steady stiffness deterioration with the increase of displacement after yielding. However, all the specimens do not perform significant strength deterioration before failure. The effect of joint geometric parameters ${\beta}$ and ${\gamma}$ of the four specimens on hysteretic performance is also discussed.

• Computers and Concrete
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• 제31권6호
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• pp.527-536
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• 2023

Fiber Reinforced Polymer (FRP) bar has emerged as a viable and sustainable replacement to steel in reinforced concrete (RC) under severe corrosive environment. The behavior of concrete columns reinforced with FRP bars, spirals, and hoops is an ongoing area of research. In this study, 3D nonlinear numerical modelling of circular concrete columns reinforced with Glass Fiber Reinforced Polymer (GFRP) bars and transversely confined with GFRP spirals were conducted using fracture-plastic model. The numerical models and experimental results are found to be in good agreement. The effectiveness of confinement was accessed through von-mises stresses, and it was found that the stresses in the concrete's core are higher with a 30 mm pitch (46 MPa) compared to a 60 mm pitch (36 MPa). The validated models are used to conduct parametric studies. In terms of axial load carrying capacity and member ductility, the effect of concrete strength, spiral pitch, and longitudinal reinforcement ratio are thoroughly investigated. The confinement effect and member ductility of a GFRP RC column increases as the spiral pitch decreases. It is also found that the confinement effect and member ductility decreased with increase in strength of concrete.

• Journal of Advanced Marine Engineering and Technology
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• 제28권6호
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• pp.922-930
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• 2004

An experimental investigation was performed to study on the generation of air bubble and air core with swirling flow in a horizontal cicular tube. To determine some characteristics of the flow, 2D PIV technique is employed for velocity measurement in water. The experimental rig is manufactured from an acryl tube. The test tube diameter of 80mm, and a length of 3000mm. The used algorithm is the gray leve cross-correlation method(Kimura et al. 1986). An Ar-ion laser is used and the light from the laser(500mW) passes through a probe to make two-dimensional light sheet. In order to make coded images of the tracer particles on one frame, an AOM(Acoustic-Optical Modulator) is used. The maximum axial velocities showed near the test tube wall at y/D =0.1 and y/D =0.9 along the test tube. The higher Reynolds number increase, the lower axial velocities are showed in the center of the test tube. The air bubbles are generated from Re =10,000 and developed into air core from the recirculating water pump rpm equal 30Hz. The pressure and temperature are measured across the test tube at X/D=3.33.