• 한국강구조학회 논문집
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• 제13권4호
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• pp.363-372
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• 2001

본 연구의 목적은 보항복형 비가새 골조의 $P-{\Delta}$영향을 실험적 방법을 통하여 조사하는데 있다. 이를 위하여 4개의 1층 1스팬의 보항복형 비가새 골조에 대한 가력실험을 실시하였다. 실험의 변수로는 기둥의 강성과 축력비를 적용하였다. 실험결과 저축력 상태의 보항복형 비가새 골조에서는 축력의 정량적인 크기가 $P-{\Delta}$효과로서 골조의 안정성에 영향을 미치는 것으로 나타났다. 그리고 최대수평하중은 기둥의 강성과 지점 회전강성에 비례하여 증가하며 저축력상태의 보항복형 비가새 골조는 붕괴가구 형성이 비교적 안정적인 상태에서 이루어짐을 알 수 있었다. 그리고 한계상태설계기준의 $B_2$ 계수는 골조의 비탄성거동시 $P-\Delta$효과를 적절히 고려하지 못하는 것으로 판단된다.

• 한국강구조학회 논문집
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• 제18권2호
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• pp.123-135
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• 2006

이 연구에서는 원형기둥-상자형보 접합부의 다이아프램 형상에 따른 거동특성과 다이아프램 설계방법에 관한 것이다. 강재 원형기둥-상자형보 접합부의 다이아프램은 상자형보 하부플랜지로부터 전달되는 집중력을 지지하게 되며, 보와 기둥의 강도 뿐만아니라 접합부의 거동에 큰 영향을 미치게 된다. 기존의 연구에서는 부정정 곡선보 모델로부터 유도된 다이아프램의 응력계산식이 제시되어 있으나, 설계식으로 활용되기에는 계산과정이 난해하고 유도과정이 비합리적이다. 또한 접합부 강도에 대한 다이 아프램의 역할을 고려하지 않음으로써 다이아프램의 합리적인 설계가 이루어 지지 못하고 있다. 따라서 이 연구에서는 접합부 다이아프램의 설계변수에 대한 비선형 유한요소 해석을 수행하여, 다이아프램의 형상에 따른 강도특성을 검토하였다. 또한 원형기둥-상자형보, 접합부 다이아프램의 이론식이 접합부의 실제 거동과 큰 차이를 나타냄을 확인하였고, 보와 기둥 및 다이아프램 강성을 고려한 강재 원형기둥 접합부 다이아프램의 설계방법을 제안하였다.

• Wind and Structures
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• 제14권2호
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• pp.85-112
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• 2011

Wind turbine structures are long slender columns with a rotor and blade assembly placed on the top. These slender structures vibrate due to dynamic environmental forces and its own dynamics. Analysis of the dynamic behavior of wind turbines is fundamental to the stability, performance, operation and safety of these systems. In this paper a simplied approach is outlined for free vibration analysis of these long, slender structures taking the soil-structure interaction into account. The analytical method is based on an Euler-Bernoulli beam-column with elastic end supports. The elastic end-supports are considered to model the flexible nature of the interaction of these systems with soil. A closed-form approximate expression has been derived for the first natural frequency of the system. This new expression is a function of geometric and elastic properties of wind turbine tower and properties of the foundation including soil. The proposed simple expression has been independently validated using an exact numerical method, laboratory based experimental measurement and field measurement of a real wind turbine structure. The results obtained in the paper shows that the proposed expression can be used for a quick assessment of the fundamental frequency of a wind turbine taking the soil-structure interaction into account.

• Structural Engineering and Mechanics
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• 제85권6호
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• pp.825-835
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• 2023

The effective buckling length factor is an important parameter in the elastic buckling analysis of steel structures. The present article aims at developing a new method that allows the determination of the buckling factor values for frames. The novelty of the method is that it considers the interaction between the bracing and the elastic supports for asymmetrical frames in particular. The approach consists in isolating a critical column within the frame and evaluating the rotational and translational stiffness of its restraints to obtain the critical buckling load. This can be achieved by introducing, through a dimensionless parameter 𝜙_i, the effects of coupling between the axial loading and bending stiffness of the columns, on the classical stability functions. Subsequently, comparative, and parametric studies conducted on several frames are presented for assessing the influence of geometry, loading, bracing, and support conditions of the frame columns on the value of the effective buckling length factor K. The results show that the formulas recommended by different approaches can give rather inaccurate values of K, especially in the case of asymmetric frames. The expressions used refer solely to local stiffness distributions, and not to the overall behavior of the structure.

• Structural Engineering and Mechanics
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• 제73권2호
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• pp.153-165
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• 2020

The effect of soil foundation plays active role in optimum design of steel space frames when included. However, its influence on design can be calculated after a long iterative procedure. So it requires longer computer time and more computational effort if it is done properly. The main purpose of this study is to investigate how these effects can be calculated in more practical way in a shorter time. The effects of semi-rigid column bases are taken into account in optimum design of steel space frames. This study is carried out by using JAYA algorithm which is a novel and practical method based on a single revision equation. The displacement, stress and geometric size constraints are considered in the optimum design. A computer program is coded in MATLAB to achieve corporation with SAP2000-OAPI (Open Application Programming Interface) for optimum solutions. Four different steel space frames including soil structure interaction taken from literature are investigated according to different semi-rigidly supported models depending on different rotational stiffness values. And the results obtained from analyses are compared with the results available in reference studies. The results of the study show that semi-rigidly supported systems in the range of appropriate rotational stiffness values offer practical solutions in a very short time. And close agreement is obtained with the studies on optimum design of steel space frames including soil effect underneath.

• Structural Engineering and Mechanics
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• 제44권1호
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• pp.85-107
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• 2012

The building frame and its foundation along with the soil on which it rests, together constitute a complete structural system. In the conventional analysis, a structure is analysed as an independent frame assuming unyielding supports and the interactive response of soil-foundation is disregarded. This kind of analysis does not provide realistic behaviour and sometimes may cause failure of the structure. Also, the conventional analysis considers infill wall as non-structural elements and ignores its interaction with the bounding frame. In fact, the infill wall provides lateral stiffness and thus plays vital role in resisting the seismic forces. Thus, it is essential to consider its effect especially in case of high rise buildings. In the present research work the building frame, infill wall, isolated column footings (open foundation) and soil mass are considered to act as a single integral compatible structural unit to predict the nonlinear interaction behaviour of the composite system under seismic forces. The coupled isoparametric finite-infinite elements have been used for modelling of the interaction system. The material of the frame, infill and column footings has been assumed to follow perfectly linear elastic relationship whereas the well known hyperbolic soil model is used to account for the nonlinearity of the soil mass.

• Journal of Information Processing Systems
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• 제13권6호
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• pp.1575-1584
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• 2017

As interest in big data has increased recently, NoSQL, a solution for storing and processing big data, is getting attention. NoSQL supports high speed, high availability, and high scalability, but is limited in areas where data integrity is important because it does not support multiple row transactions. To overcome these drawbacks, many studies are underway to support multiple row transactions in NoSQL. However, existing studies have a disadvantage that the number of transactions that can be processed per unit of time is low and performance is degraded. Therefore, in this paper, we design and implement a multi-row transaction system for data integrity in big data environment based on HBase, a column-based NoSQL which is widely used recently. The multi-row transaction system efficiently performs multi-row transactions by adding columns to manage transaction information for every user table. In addition, it controls the execution, collision, and recovery of multiple row transactions through the transaction manager, and it communicates with HBase through the communication manager so that it can exchange information necessary for multiple row transactions. Finally, we performed a comparative performance evaluation with HAcid and Haeinsa, and verified the superiority of the multirow transaction system developed in this paper.

• 한국전산구조공학회논문집
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• 제15권1호
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• pp.165-172
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• 2002

일반적으로 모멘트 지지 강구조물은 유한요소법에 의해 이상화되고 해석되어 왔으며 기둥과 기둥의 연결부, 기둥과 보의 접합부의 정확한 비선형 해석 결과를 위해 많은 노력을 해온 반면에 기둥의 지지부에 대한 해석은 고정단 또는 힌지로 간단하게 이루어져 왔다 그러나 실제로 기둥의 지지부는 고정단도 힌지도 아닌 그 중간인 반강성으로 거동한다. 본 논문에서는 이러한 기둥 지지부를 반강성모델을 이용해서 해석하고 그 결과를 고찰하여 기둥 지지부의 강성 및 강도의 변화가 미치는 영향을 평가하였다. 미국 시방서에 의해 설계된 전형적인 두개의 3층 모멘트지지 강구조물을 이미 개발된 강성도법 및 유연도법에 기초한 7iber 유한 요소를 사용하여 해석하였다. 기등의 지지부는 고정단과 힌지사이에 있는 반강성 지지부를 모델하기 위해 다양한 강성도를 갖는 회전 스프링을 사용하였다. 실제의 기둥 지지부와 가깝게 모델된 반강성 지지부를 갖는 구조물의 해석 결과는 고정지지부를 갖는 구조물과 어느 정도 비슷한 결과를 보여주었다. 또한 pushover 해석과 비선형 시간 이력 해석을 통해 기둥 지지부의 강성도가 감소함에 따라 1층 보의 소요 처짐각(rotational demand)이 증가하는 현상이 관찰되었다 시공상의 문제 및 노화로 인한 기동 지지부의 강성도 감소는1층의 접합부에 대한 소요 터짐각의 증가를 유발하고 그것은 곧 soft-story mechanism을 유발하게 된다.

• Advances in Computational Design
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• 제3권1호
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• pp.49-69
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• 2018

This paper shows an optimal design for reinforced concrete rectangular combined footings based on a criterion of minimum cost. The classical design method for reinforced concrete rectangular combined footings is: First, a dimension is proposed that should comply with the allowable stresses (Minimum stress should be equal or greater than zero, and maximum stress must be equal or less than the allowable capacity withstand by the soil); subsequently, the effective depth is obtained due to the maximum moment and this effective depth is checked against the bending shear and the punching shear until, it complies with these conditions, and then the steel reinforcement is obtained, but this is not guaranteed that obtained cost is a minimum cost. A numerical experimentation shows the model capability to estimate the minimum cost design of the materials used for a rectangular combined footing that supports two columns under an axial load and moments in two directions at each column in accordance to the building code requirements for structural concrete and commentary (ACI 318S-14). Numerical experimentation is developed by modifying the values of the rectangular combined footing to from "d" (Effective depth), "b" (Short dimension), "a" (Greater dimension), "${\rho}_{P1}$" (Ratio of reinforcement steel under column 1), "${\rho}_{P2}$" (Ratio of reinforcement steel under column 2), "${\rho}_{yLB}$" (Ratio of longitudinal reinforcement steel in the bottom), "${\rho}_{yLT}$" (Ratio of longitudinal reinforcement steel at the top). Results show that the optimal design is more economical and more precise with respect to the classical design. Therefore, the optimal design presented in this paper should be used to obtain the minimum cost design for reinforced concrete rectangular combined footings.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2001년도 추계학술발표대회
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• pp.613-616
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• 2001

이 연구에서는 가수분해효소인 Orientase 22BF를 5가지 당체에 흡착법을 사용해서 고정시키고 충전층반응기에 넣어 흡수도를 비교함으로써 고정화효율을 평가하였다. 결과는 다음과 같다. 최적 담체는 Celite IT 640, Duolite A568, 그리고 Silicagel 60이었으며, 담체의 최적조건은 pH 5.0, 온도 $50^{\circ}C$로 나타났다. 또한 이 연구에서 peptide solution을 얻기 위하여 난황 단백질을 사용하였다.