• Structural Engineering and Mechanics
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• 제56권1호
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• pp.49-56
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• 2015

Dynamic compaction (DC) is a useful method for improvement of granular soils. The method is based on falling a tamper (weighting 5 to 40 ton) from the height of 15 to 30 meters on loose soil that results in stress distribution, vibration of soil particles and desirable compaction of the soil. Propagation of the waves during tamping affects adjacent structures and causes structural damage or loss of performance. Therefore, determination of the safe or critical distance from tamping point to prevent structural hazards is necessary. According to FHWA, the critical distance is defined as the limit of a particle velocity of 76 mm/s. In present study, the ABAQUS software was used for numerical modeling of DC process and determination of the safe distance based on particle velocity criterion. Different variables like alluvium depth, relative density, and impact energy were considered in finite element modeling. It was concluded that for alluvium depths less than 10 m, reflection of the body waves from lower boundaries back to the soil and resonance phenomenon increases the critical distance. However, the critical distance decreases for alluvium depths more than 10 m. Moreover, it was observed that relative density of the alluvium does not significantly influence the critical distance value.

• Computers and Concrete
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• 제1권3호
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• pp.303-324
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• 2004

The Component-Based Software Development (CBSD) has established itself as a sound paradigm in the software engineering discipline and has gained wide spread acceptance in the industry. The CBSD relies on the availability of standard software components for encapsulation of specific functionality. This paper presents the framework for the development of a software component for the design of general member cross-sections. The proposed component can be used in component-based structural engineering software or as a stand-alone program developed around the component. This paper describes the use-case scenarios for the component, its design patterns, object models, class hierarchy, the integrated and unified handling of cross-section behavior and implementation issue. It is expected that a component developed using the proposed patterns and model can be used in analysis, design and detailing packages to handle reinforced concrete, partially prestressed concrete, steel-concrete composite and steel sections. The component can provide the entire response parameters of the cross section including determination of geometric properties, elastic stresses, flexural capacity, moment-curvature, and ductility ratios. The component can also be used as the main computational engine for stand-alone section design software. The component can be further extended to handle the retrofitting and strengthening of cross-sections, shear and torsional response, determination of fire-damage parameters, etc.

• Geomechanics and Engineering
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• 제20권5호
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• pp.411-420
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• 2020

Numbers fitting-curve equations have been proposed to predict soil-water retention curve (SWRC) whose parameters have no definitude physical meaning. And these methods with precondition of measuring SWRC data is time-consuming. A simplified directly method to estimate SWRC without parameters obtained by fitting-curve is proposed. Firstly, the total SWRC can be discretized into linear segments respectively. Every segment can be represented by linear formulation and every turning point can be determined by the pore-size distribution (PSD) of Mercury Intrusion Porosimetry (MIP) tests. The pore diameters governing the air-entry condition (AEC) and residual condition (RC) can be determined by the PSDs of MIP test. The PSD changes significantly during drying in SWR test, so the determination of AEC and RC should use the PSD under corresponding suction conditions. Every parameter in proposed equations can be determined directly by PSD without curve-fitting procedure and has definitude physical meaning. The proposed equations give a good estimation of both unimodal and bimodal SWRCs.

• 한국산업융합학회 논문집
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• 제23권4_2호
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• pp.627-635
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• 2020

In this study, the optimal support span determination of pipeline system was carried out in consideration of the effects of seismic loads. The theoretical support and structural analysis were used to determine the optimal support span of piping system according to pipe diameter using theoretical and structural deflection criteria. The reliability of the analysis results was secured by comparing the structural and theoretical results. In particular, the optimum support span of piping system was obtained by considering the effects of seismic load, and the optimal support span of pipe diameter and piping system tended to be proportional to each other. When considering the effects of earthquakes on different pipe diameters(300~2,500mm), the span length is reduced by up to 48% at the allowable stress criterion, and the pipe span length is reduced by up to 5.9% at the deflection criterion. It can be seen that the effect of the seismic load on the determination of the piping span length has a greater effect on the stress than the displacement.

• 한국융합학회논문지
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• 제10권11호
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• pp.533-541
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• 2019

본 연구는 간호대학생의 자기조절학습에 영향을 주는 요인들의 구조 방정식 모형을 만들고 검증하기 위함이다. 이를 위해 재학 중인 간호대학생들에게 자가보고식 설문지를 작성하게 하여 273부의 자료를 구조방정식 모형으로 분석하였다. 분석결과 모형 적합지수는 적절한 수준을 나타내었고, 6개 경로 중 5개 경로는 통계적으로 유의미하여 분산의 68%를 설명하였다. 따라서 간호대학생의 자기조절학습을 증진시킬 수 있도록 자기결정동기, 대인관계유능, 성취목표지향을 향상시키는 교육이 필요하며, 이를 위해 간호대학생의 자율성과 관계성을 증진시킬 역량 강화 프로그램이 개발되어야 할 것이다.

• Wind and Structures
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• 제18권4호
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• pp.347-373
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• 2014

Since its development in the early 1980's the force balance technique has become a standard method in the efficient determination of structural loads and responses. Its usefulness lies in the simplicity of the physical model, the relatively short records required from the wind tunnel testing and its versatility in the use of the data for different sets of dynamic properties. Its major advantage has been the ability to provide results in a timely manner, assisting the structural engineer to fine-tune their building at an early stage of the structural development. The analysis of the wind tunnel data has evolved from the simple un-coupled system to sophisticated methods that include the correction for non-linear mode shapes, the handling of complex geometry and the handling of simultaneous measurements on multiple force balances for a building group. This paper will review some of the components in the force balance data analysis both in historical perspective and in its current advancement. The basic formulation of the force balance methodology in both frequency and time domains will be presented. This includes all coupling effects and allows the determination of the resultant quantities such as resultant accelerations, as well as various load effects that generally were not considered in earlier force balance analyses. Using a building model test carried out in the wind tunnel as an example case study, the effects of various simplifications and omissions are discussed.

• Earthquakes and Structures
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• 제10권4호
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• pp.735-755
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• 2016

This article presents a proposed analytical methodology to determine seismic force-resisting system R-values for steel diagrid framed systems. As current model building codes do not explicitly address the seismic design performance factors for this new and emerging structural system, the purpose of this study is to provide a sound and reliable basis for defining such seismic design parameters. An approach and methodology for the reliable determination of seismic performance factors for use in the design of steel diagrid framed structural systems is proposed. The recommended methodology is based on current state-of-the-art and state-of-the practice methods including structural nonlinear dynamic analysis techniques, testing data requirements, building code design procedures and earthquake ground motion characterization. In determining appropriate seismic performance factors (R, ${\Omega}_O$, $C_d$) for new archetypical building structural systems, the methodology defines acceptably low values of probability against collapse under maximum considered earthquake ground shaking.

• Journal of Power Electronics
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• 제9권4호
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• pp.631-642
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• 2009

The sun is a useful reference direction because of its brightness relative to other astronomical objects and its relatively small apparent radius as viewed by spacecrafts near the Earth. Most satellites use solar power as a source of energy, and so need to make sure that solar panels are oriented correctly with respect to the sun. Also, some satellites have sensitive instruments that must not be exposed to direct sunlight. For all these reasons, sun sensors are important components in spacecraft attitude determination and control systems. To minimize components and structural mass, some components have multiple purposes. The solar cells will provide power and also be used as coarse sun sensors. A coarse Sun sensor is a low-cost attitude determination sensor suitable for a wide range of space missions. The sensor measures the sun angle in two orthogonal axes. The Sun sensor measures the sun angle in both azimuth and elevation. This paper presents the development of a model to determine the attitude of a small cube-shaped satellite in space relative to the sun's direction. This sensor helps small cube-shaped Pico satellites to perform accurate attitude determination without requiring additional hardware.

• 한국보육지원학회지
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• 제10권6호
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• pp.25-42
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• 2014

본 연구는 유아의 자기결정력에 영향을 미치는 주요 변인들의 상대적 영향력을 규명하는데 연구의 목적을 두었다. 유아의 자기결정력에 관련된 주요 변인으로 유아의 자아존중감, 자기조절력 및 놀이성을 포함하였으며, 특히 유아의 자아존중감이 유아의 놀이성과 자기결정력 간의 관계에서 매개역할을 수행하는 가를 검증하고자 하였다. 본 연구의 목적을 달성하기 위해 현재 어린이집에 재원하고 있는 만4,5세 유아-어머니 총 337쌍을 연구대상으로 선정하였다. 연구대상 유아의 놀이성은 연구자의 현장관찰을 통해, 유아의 자기결정력, 자아존중감 및 자기조절력은 이들의 담임교사의 설문과 질문을 통해, 그리고 어머니-유아 간 조화적합성은 연구대상 어머니의 설문지를 통해 각각의 연구 자료를 수집하였다. 본 연구의 주요 결과를 살펴보면, 첫째, 유아의 자기결정력은 유아의 자아존중감, 자기조절력, 놀이성은 직접적으로, 어머니-유아 간 조화적합성은 간접적으로 영향을 미치는 것으로 나타났다. 아울러 유아의 자아존중감은 자기결정력과 어머니-유아 간 조화적합성 사이에서 완전 매개역할을, 자기결정력과 자기조절력, 놀이성 사이에서는 부분 매개역할을 수행하는 것으로 나타났다.

• BMB Reports
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• 제37권1호
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• pp.28-34
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• 2004

The discovery of biochemical and cellular functions of unannotated gene products begins with a database search of proteins with structure/sequence homologues based on known genes. Very recently, a number of frontier groups in structural biology proposed a new paradigm to predict biological functions of an unknown protein on the basis of its three-dimensional structure on a genomic scale. Structural proteomics (genomics), a research area for structure-based functional discovery, aims to complete the protein-folding universe of all gene products in a cell. It would lead us to a complete understanding of a living organism from protein structure. Two major complementary experimental techniques, X-ray crystallography and NMR spectroscopy, combined with recently developed high throughput methods have played a central role in structural proteomics research; however, an integration of these methodologies together with comparative modeling and electron microscopy would speed up the goal for completing a full dictionary of protein folding space in the near future.