• 한국공간구조학회논문집
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• 제20권4호
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• pp.93-100
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• 2020

In this study, structural characteristics were analyzed by combining gravity load and lateral loads such as seismic loads through static analysis of example structures, and the static characteristics of the twisted structure according to the plane rotation angle were also analyzed. Example structures were selected as regular structure, and twisted structures; 1.0, 2.0, and 3.0 degree angle of rotation per story, and static analysis was performed by the load combination case 1 and case 2. As a result the story drift ratio of the twisted-shaped structure also increased as the plane rotation angle per story increased. The eccentricity according to the load combination was the highest in the lower stories of all analysis models, and the eccentricity was found to be larger as the rotation angle decreased. The twisted-shaped structure was more responsible for the bending moment of the column than the regular structure, and the vertical member axial force of all analysis models was almost similar.

• 한국공간구조학회논문집
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• 제21권4호
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• pp.23-30
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• 2021

In this paper, a twisted shape structure with an elevation form favorable to the resistance of vibration caused by wind loads is selected from among the forms of high-rise buildings. The analytical model is a square, triangular, and hexagonal plane with a plane rotation angle of one degree from 0 to 3 degrees per each story. As a result of the analysis, as the twist angle increased, story drift ratio is increased. Responses with different eccentricity rates were shown by analytical models. Therefore planar shapes designed symmetrically to the horizontal axis of X and Y are considered advantageous for eccentricity and torsion deformation. In the case of the bending moment of the column, the response was amplified in the column supporting the base floor, the roof floor, the floor in which the cross-section of the vertical member changes, and the floor having the same number of nodes as the base floor. Finally, the axial force response of the column is determined to be absolutely affected by the gravity load compared to the lateral load.

• 한국지진공학회논문집
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• 제26권5호
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• pp.203-209
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• 2022

A simplified method for earthquake response analysis of a rectangular liquid storage tank is proposed with fluid-structure interaction considered. In order to simplify the complex three-dimensional structural behavior of a rectangular liquid storage tank, it is assumed that structural deformation does not occur in the plane parallel to the direction in which the earthquake ground motion is applied but in the plane perpendicular to the direction. The structural deformation is approximated by combining the natural modes of the simple beam and the cantilever beam. The hydrodynamic pressure, the structure's mass and stiffness, and the hydrodynamic pressure's added mass are derived by applying the Rayleigh-Ritz method. The natural frequency, structural deformation, pressure, effective mode mass, and effective mode height of the rectangular liquid storage tank are obtained. The structural displacement, hydrodynamic pressure, base shear, and overturning moment are calculated. The seismic response analysis of an example rectangular liquid storage tank is performed using the proposed simplified approach, and its accuracy is verified by comparing the results with the reference solution by the finite element method. Existing seismic design codes based on the hydrodynamic pressure in rigid liquid storage tanks are observed to produce results with significant errors that cannot be ignored.

• Geomechanics and Engineering
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• 제34권6호
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• pp.611-621
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• 2023

This paper presents the results of a numerical investigation of the effect of geotextile reinforcement on underlying buried pipe behavior using PLAXIS 3D. In this study, variable parameters such as the in-plane stiffness of the geotextile, the pipe stiffness, the soil stiffness, the footing width, the geotextile width, and the location of the geotextile reinforcement layer are investigated. Deflections and bending moments acting on the pipe are evaluated for different combinations of variables and are presented graphically. It is observed that with an increase in the in-plane stiffness of the geotextile reinforcement, there is a tendency for a decrease in both deflections in the pipe and bending moments acting on the pipe. Conversely, with an increase in the pipe stiffness, geotextile reinforcement efficiency decreases. In the investigated region of soil stiffness, for the given pipe and geotextile stiffness, an optimum efficiency of geotextile is observed in medium dense soils. Further, it is shown that relative lengths of geotextile and footing has an important role on geotextile efficiency. Lastly, it is also demonstrated that relative location of geotextile layer with respect to the buried pipe plays an important role on the geotextile efficiency in reducing the bending moments acting on the pipe and deflections in the pipe. In general, geotextiles are more efficient in reducing the bending moments as opposed to reducing deflections of the pipe. Numerical validation is done with an experimental study from the literature to observe the applicability of the numerical model used.

• 폴리머
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• 제30권4호
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• pp.362-366
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• 2006

Pentacene을 폴리이미드(PI) 배향막 위에 증착하면 기판 위에 수직으로 배열하는 것을 편광 FTIR 실험을 이용하여 확인하였다. Pentacene 이 PI 필름 위에 수직으로 증착할 때, 러빙하지 않은 즉, 등방성인 PI 필름 위에서는 특정한 방향성이 없이 배열하는 반면 러빙한 PI 필름 위에서는 러빙 방향과 평행하게 pentacene의 ring 평면이 배열하였다. Pentacene 특성 피크 중 ring 평면에 평행한 transition dipole moment 를 가지는 $1296cm^{-1}$ 밴드는 러빙 방향과 평행일 때 그리고 ring 평면에 수직한 진동운동의 $908cm^{-1}$ 밴드는 러빙 방향에 수직인 편광 IR 스펙트럼 에서 피크가 크게 나타나는 것이 관찰되었다. 이와 같은 평광 FTIR 실험 결과는 기판에 수직으로 증착하는 pentacene 분자들이 PI 필름의 러빙 방향과 평행하게 ring 평면이 배열을 할 때 나타날 수 있는 것으로, PI 사슬들의 배향이 pentacene 분자들의 배향에 영향을 미치는 것을 보여주는 것이다.

• 한국구조물진단유지관리공학회 논문집
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• 제23권6호
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• pp.77-83
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• 2019

원자력발전소에 지진격리장치를 설치하면 지진에 의한 하중을 지진격리장치가 담당하면서 설치 전보다 큰 변위가 발생하게 될 것으로 예상되며, 변위증가에 따라 일부 설비의 지진리스크가 증가될 가능성이 있다. 특히 지진격리된 구조물과 일반 구조물을 연결하는 설비인 배관 시스템의 경우 지진리스크가 크게 증가될 것으로 예상된다. 본 연구에서는 원자력발전소 배관 시스템의 취약부위인 강재 배관 Tee의 한계상태를 누수로 정의하고 면내반복가력시험을 수행하였다. 강재 배관 Tee의 모멘트와 변형각은 기존의 센서를 이용한 계측이 어려우므로 이미지 신호를 이용하여 측정하였다. 본 연구에서는 3인치 강재 배관 Tee의 모멘트와 변형각의 관계를 이용한 누수 선도 및 저주기 피로 곡선들을 제시하였다.

• Journal of Biosystems Engineering
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• 제2권1호
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• pp.33-48
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• 1977

Transporting agricultural products and the other material by the two-wheel-tractor (power-tiler)and trailer system may be one of its most widely used farming functions.The safety and hitching load for all the previaling performing conditions may be the general concern over the operation of the tiller-trailer system. In this study, a mathematical model to determine the static and dynamic forces excerting on the hitch point were developed . Based on the analysis of the model and the field measurements. the limiting hitching load and critical slope were analyzed. The results of the study are summarized as follows ; 1) The limit angle of slope land for the safety steering that two-wheel tractor-single axle trailer system was able to transport agricultural products was the direct angle (${\gamma}$) = 8 ; the cross angle$\beta$) 15 ; and it was decreased in accordance with the increase of carrying load ($W_4). 2) The critical velocity for safe operation in case of running on downward hill road was about 1.08m/sec. 3) The limiting carrying load for the safe steering was W$_4$=600kg. The degree of the safe steering for different braking methods was given in order as follows ; Simulataneous braking the tractor and trailer , braking the trailer only, and braking tractor only. 4) Among the three components of impact loads excerting on the hitch point, the component in the lateral direction ($P_{Vy}$) was near zero in spite of increase of hitching load ($W_4) , while the components in the other two mutually perpedicular directions ($P_{Vx}$ and ($P_{Vz}$) ) had larger values in horizontal plane than those in the slope lands. 5) Moment of forces on the lateral direction (M$y$) had the largest value among the three components of impact moment acting on the hitch point, however all the components were sharply increased in accordance with the increase of hitching loads ($W_4. Three components of the moment were the negative values.

• 한국강구조학회 논문집
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• 제13권3호
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• pp.289-299
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• 2001

본 논문은 직각펀형 외다이아프램 형식의 각형강관-H형강보 접합부의 반강접 특성을 파악하기 위하여 기존 실험결과를 수집하여 모든 실험체를 기준이 되는 실험방법과 동일하게 모델링하여 유한요소해석을 실시하였다. 이 해석결과를 실험결과와 비교 검증하여 해석결과의 신뢰성을확보, 이를 준용하는 것으로 하여 본 접합부형식의 반강접거동에 영향을 미치는 주요한 변수를 파악하고 차후 골조해석에 적용 가능한 적절한 모멘트-회전각 곡선을 제안, 함수를 구성하는 세가지 파라메타에 대하여 다중선형회귀분석을 실사하였다.

• International Journal of Concrete Structures and Materials
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• 제18권3E호
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• pp.173-181
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• 2006

The objectives of this study are to evaluate the reliability of an existing nonlinear analysis program for predicting the inelastic behavior of reinforced concrete frame with seismic details and to observe the redistribution of the internal forces, which can not be easily measured by an experiment. In order to carry out this task, the nonlinear analysis program of IDARC 2D(3) was run on a 2-bay, 2-story moment-resisting reinforced concrete plane frame with seismic details. (1) The effort to obtain the results of the analysis similar to those of experiment was made by determining the appropriate values of model parameters. The comparison of the analysis results with those of experiment and the observation of the distribution of internal forces obtained through nonlinear analysis points to the following conclusions. (1) The overall relationship between lateral load and lateral displacement given by the analysis is similar to that of experiment. However, the values of initial stiffness and the amount of energy dissipation in the initial displacement steps given by the analysis show larger values than those of experiment. (2) The analysis provided detailed information on the distribution and redistribution of internal forces and proved useful in elucidating the crack pattern, the sequence of the occurrence of plastic hinges, and the failure or yielding mechanism for the whole structure. (3) In spite of the similarity in overall behavior of analysis and experiment, there exists a significant discrepancy in some local behaviors. Furthermore, the hysteresis in the relationship between moment and curvature in some column ends have shown sudden deteriorations in strength, which can not be interpreted satisfactorily at the present time. Therefore, it is necessary to develop a better analytical model to fill this knowledge gap.

• 한국통신학회논문지
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• 제31권9A호
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• pp.913-919
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• 2006

본 논문에서는 스트립 폭과 격자주기, 비유전율, 유전체 층의 두께, 그리고 TE(transverse electric) 평면파의 입사각에 따른 접지된 다층 유전체위의 저항띠 격자구조에 의한 TE 산란 문제를 수치해석 방법인 FGMM(Fourier-Galerkin Moment Method)을 이용하여 해석하였다. 유도되는 표면전류밀도는 간단한 함수인 지수함수를 사용하여 Fourier 급수로 전개하였다. 전반적으로 다층유전체의 비유전율과 두께가 증가함에 따라 반사전력이 증가하였고, 반사전력의 급변점들은 공진효과에 기인한 것으로 과거에 wood's anomallies$^{[7]}$라고 불리워졌다. 제안된 방법의 검증을 위하여 기존의 완전도체 경우인 균일 저항율 R = 0에 대한 정규화된 반사전력의 수치결과는 기존 논문들과 일치하였다.