• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2005년도 학술발표회 논문집
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• pp.324-330
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• 2005

The flexural strength and ductility capacity of reinforced concrete columns are largely dependent on the amount of transverse steel. However, current design code does not specify the confinement effect of transverse steels in strength calculation. A non-linear moment-curvature analysis of RC column sections was conducted in order to develop PM interaction diagram considering transverse reinforcement effects. In this paper, a more reasonable application method of PM interaction diagram considering transverse steel amounts is introduced and proposed, based on moment-curvature non-linear analysis. Also, we proposed simplified method to use. easily in practical design.

• Structural Engineering and Mechanics
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• 제23권5호
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• pp.563-577
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• 2006

This study involves a series of experiments on the buckling strength of eccentrically compressed cold-formed stainless steel square hollow-section columns. The principal parameters in this study are slenderness ratios ($L_k/r$ = 30, 50, 70) and magnitude of eccentricity e (0, 25, 50, 75, 100 mm) on the symmetrical end-moment. The objectives of this paper are to obtain the buckling loads by conducting a series of experiments and to compare the behavior of the eccentrically compressed cold-formed stainless steel square hollow-section columns with the results of the analysis. The ultimate buckling strength of the square-section members were determined with the use of a numerical method in accordance with the bending moment-axial force (M-P) interaction curves. The behavior of each specimen was displayed in the form of a moment-radian (M-${\theta}$) relationship. The numerically obtained ultimate-buckling interaction curves of the beam columns coincided with the results of the experiments.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2012년도 제38회 춘계학술대회논문집
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• pp.239-243
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• 2012

This paper is concerned with turbulent flow computations using Large Eddy Simulation (LES) and the flow interaction of vortex shedding in a cylindrical duct flow driven by mass blowing through the wall. The purpose is to analyze non-linear combustion characteristics in the presence of vortex shedding generated in a hybrid rocket motor. Experimental studies have shown sudden changes in pressure (referred as a DC-shift), which depend on the strength of vortex strength of incoming flow. The combustion instability because of a sudden change in pressure fluctuations is mainly related with the interaction between vortex shedding. Therefore LES computation on a duct with injected normal blowing was performed to simulate the turbulent flow interactions with the behaviors of vortices and vortex structures along the injected wall.

• 한국유통학회지:유통연구
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• 제16권2호
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• pp.95-118
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• 2011

본 연구는 다음과 같은 연구목적을 가진다. 첫째, 프랜차이즈 시스템에서 사회연결망 밀도와 중앙성이 가맹점의 가맹본부와의 정보공유와 다른 가맹점들과의 정보공유에 미치는 영향에 대한 관계를 실증적으로 밝히고자 한다. 둘째, 앞서 제시한 관계들에 있어 가맹점과 가맹본부 간의 유대강도의 조절역할을 하는지에 대하여 탐색적으로 확인하고자 한다. 셋째, 실증분석의 결과를 토대로 학문적 실무적 시사점을 제시하고자 한다. 본 연구는 실증분석을 하기 위하여 부산지역에 소재한 프랜차이즈 가맹점들을 대상으로 설문조사를 실시하였으며, 설문응답의 신뢰성을 높이기 위해서 가맹점의 점주와 점장을 중심으로 설문조사 하였다. 회수된 설문지는 총 200부이며, 이 중 무성의하게 응답한 11부를 제외한 189부를 실증분석에 사용하였다. 평균변환법과 위계적 다중회귀분석법을 사용하여 가설들을 검증한 결과는 다음과 같다. 첫째, 정보공유 대상이 가맹본부인 경우 사회연결망 중앙성, 유대강도, 밀도 및 중앙성과 유대강도의 상호작용이 정보공유에 유의하게 영향을 미치는 것으로 나타났다. 둘째, 정보공유 대상이 다른 가맹점인 경우 사회연결망 중앙성이 정보공유에 유의한 영향을 미치는 것으로 나타났다. 마지막으로 본 연구의 실증분석 결과를 토대로 학문적 실무적 시사점과 본 연구의 한계점 및 향후 과제를 제시하였다.

• Structural Engineering and Mechanics
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• 제66권5호
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• pp.637-648
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• 2018

When the centers of mass and stiffness of a building do not coincide, the structure experiences torsional responses. Such systems can consist of the underlying soil and the super-structure. The underlying soil may modify the earthquake input motion and change structural responses. Specific effects of the input motion shall also not be ignored. In this study, seismic demands of asymmetric buildings considering soil-structure interaction (SSI) under near-fault ground motions are evaluated. The building is modeled as an idealized single-story structure. The soil beneath the building is modeled by non-linear finite elements in the two states of loose and dense sands both compared with the fixed-base state. The infinite boundary conditions are modelled using viscous boundary elements. The effects of traditional and yield displacement-based (YDB) approaches of strength and stiffness distributions are considered on seismic demands. In the YDB approach, the stiffness considered in seismic design depends on the strength. The results show that the decrease in the base shear considering soft soil induced SSI when the YDB approach is assumed results only in the center of rigidity to control torsional responses. However, for fixed-base structures and those on dense soils both centers of strength and rigidity are controlling.

• Geomechanics and Engineering
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• 제14권1호
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• pp.29-42
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• 2018

This paper presents the results of an empirical study in which square rock-like blocks containing two parallel pre-existing rough non-persistent joints were subjected to uniaxial compression load. The main purpose of this study was to investigate uniaxial compressive strength and deformation modulus of jointed specimens. Response Surface Method (RSM) was utilized to design experiments and investigate the effect of four joint parameters, namely joint roughness coefficient (JRC), bridge length (L), bridge angle (${\gamma}$), and joint inclination (${\theta}$). The interaction of these parameters on the uniaxial compressive strength (UCS) and deformation modulus of the blocks was investigated as well. The results indicated that an increase in joint roughness coefficient, bridge length and bridge angle increased compressive strength and deformation modulus. Moreover, increasing joint inclination decreased the two mechanical properties. The concept of 'interlocking cracks' which are mixed mode (shear-tensile cracks) was introduced. This type of cracks can happen in higher level of JRC. Initiation and propagation of this type of cracks reduces mechanical properties of sample before reaching its peak strength. The results of the Response Surface Methodology showed that the mutual interaction of the joint parameters had a significant influence on the compressive strength and deformation modulus.

• Structural Engineering and Mechanics
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• 제28권3호
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• pp.295-316
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• 2008

In the present paper a mechanical model to predict the compressive response of high strength short concrete columns with square cross-section confined by transverse steel is presented. The model allows one to estimate the equivalent confinement pressures exercised by transverse steel during the loading process taking into account of the interaction of the stirrups with the inner core both in the plane of the stirrups and in the space between two successive stirrups. The lateral pressure distributions at hoop levels are obtained by using a simple model of elastic beam on elastic medium simulating the interaction between stirrups and concrete core, including yielding of steel stirrups and damage of concrete core by means of the variation in the elastic modulus and in the Poisson's coefficient. Complete stress-strain curves in compression of confined concrete core are obtained considering the variation of the axial forces in the leg of the stirrup during the loading process. The model was compared with some others presented in the literature and it was validated on the basis of the existing experimental data. Finally, it was shown that the model allows one to include the main parameters governing the confinement problems of high strength concrete members such as: - the strength of plain concrete and its brittleness; - the diameter, the pitch and the yielding stress of the stirrups; - the diameter and the yielding stress of longitudinal bars; - the side of the member, etc.

• International Journal of Naval Architecture and Ocean Engineering
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• 제5권1호
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• pp.101-115
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• 2013

This paper examines the application of structural reliability analysis to submarine pressure hulls to clarify the merits of probabilistic approach in respect thereof. Ultimate strength prediction methods which take the inelastic behavior of ring-stiffened cylindrical shells and hemi-spherical shells into account are reviewed. The modeling uncertainties in terms of bias and coefficient of variation for failure prediction methods in current design guidelines are defined by evaluating the compiled experimental data. A simple ultimate strength formulation for ring-stiffened cylinders taking into account the interaction between local and global failure modes and an ultimate strength formula for hemispherical shells which have better accuracy and reliability than current design codes are taken as basis for reliability analysis. The effects of randomness of geometrical and material properties on failure are assessed by a prelimnary study on reference models. By evaluation of sensitivity factors important variables are determined and comparesons are made with conclusions of previous reliability studies.

• Steel and Composite Structures
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• 제42권2호
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• pp.191-207
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• 2022

Undoubtedly, the employment of direct bond interaction between steel and concrete is preceding the other mechanisms because of its ease of construction. However, the large scatter in the experimental data about the issue has hindered the efforts to characterize bond strength. In the following research, the direct bond interaction and bond-slip behavior of CFTs with circular cross-section were examined through repeated load-reversed push-out tests until four cycles of loading. The influence of different parameters including the diameter of the tube and the use of shear tabs were assessed. Moreover, the utilization of expansive concrete and external spirals was proposed and tested as ways of improving bond strength. According to the results section dimensions, tube slenderness, shrinkage potential of concrete, interface roughness and confinement are key factors in a natural bond. Larger diameters will lead to a considerable drop in bond strength. The use of shear tabs by their associated bending moments increases the bond stress up to eight times. Furthermore, employment of external spirals and expansive concrete have a sensible effect on enhancing bonds. Macro-locking was also found to be the main component in achieving bond strength.

• 한국콘텐츠학회논문지
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• 제9권10호
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• pp.427-435
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• 2009

본 연구는 일반 성인 남성을 대상으로 걷기운동이 근기능의 변화에 어떤 영향을 미치는지 알아보기 주4회 8주간 속보 트레이닝 참여에 따른 하지근력의 최대 힘효율과 평균 파워의 변화를 살펴보았다. 그 결과 다음과 같은 결론을 얻었다. 첫째, $60^{\circ}/sec$의 최대 힘효율, 평균파워는 신근과 굴근에서 유의한 상호작용이 나타났으며, 8주 전후 트레이닝은 최대 힘효율, 평균파워는 증가하였다. 둘째, $120^{\circ}/sec$의 최대 힘효율, 평균파워는 신근과 굴근에서 유의한 상호작용이 나타났으며, 8주 전후 트레이닝은 최대 힘효율, 평균파워는 증가하였다. 셋째, $180^{\circ}/sec$의 최대 힘효율, 평균파워는 신근과 굴근에서 유의한 상호작용이 나타났으며, 8주 전후 트레이닝은 최대 힘효율, 평균파워는 증가하였다. 결론적으로 걷기 운동은 등속성 근기능의 굴근과 신근의 개선에 긍정적으로 작용하였다. 본 연구자는 차후 연구에서는 다양한 부하와 계획을 등속성 근기능의 평가가 필요하리라 사료된다.