• 한국안전학회지
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• 제26권2호
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• pp.62-69
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• 2011

This paper presents a new simple two-dimensional frame finite element able to accurately estimate the load-carrying capacity of reinforced concrete beams flexurally strengthened externally bonded fiber reinforced polymer (FRP) strips and plates. The proposed analysis model considers distributed plasticity with layer-discretization of the cross-sections and the bond-slip behavior of epoxy layer. The proposed model is used to predict the load-carrying capacity and the applied load-midspan deflection response of RC beams subjected to bending loading. Numerical simulations and experimental measurements are compared based on numerous tests available in the literature and published by different authors. The numerically simulated response agree remarkably well with the corresponding experimental results. Thus, the proposed model is suitable for efficient and accurate modeling and analysis of flexural strengthening of RC beams with externally bonded FRP sheets/plates and for practical use in design-oriented parametric studies.

• 한국공간구조학회논문집
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• 제22권4호
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• pp.39-48
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• 2022

The energy dissipation of inverted V-type eccentric steel braced frames can be achieved through the yielding of a slit link, through yielding of a number of strips between slits when the frame is subjected to inelastic cyclic deformation. On the other hand, the development of seismic resistance system without residual deformation is obtained by applying the superelasdtic shape memory alloy (SMA) material into the brace and link elements. This paper presents results from a systematic three-dimensional nonlinear finite element analysis on the structural behavior of the eccentric bracing systems subjected to cyclic loadings. A wide scope of structural behaviors explains the horizontal stiffness, hysteretic behaviors, and failure modes of the recentering eccentric bracing system. The accurate results presented here serve as benchmark data for comparison with results obtained using modern experimental testing and alternative theoretical approaches.

• 로봇학회논문지
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• 제3권1호
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• pp.23-32
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• 2008

This paper presents a task planning system for a steward robot, which has been developed as an interactive intermediate agent between an end-user and a complex smart home environment called the ISH (Intelligent Sweet Home) at KAIST (Korea Advanced Institute of Science and Technology). The ISH is a large-scale robotic environment with various assistive robots and home appliances for independent living of the elderly and the people with disabilities. In particular, as an approach for achieving human-friendly human-robot interaction, we aim at 'simplification of task commands' by the user. In this sense, a task planning system has been proposed to generate a sequence of actions effectively for coordinating subtasks of the target subsystems from the given high-level task command. Basically, the task planning is performed under the framework of STRIPS (Stanford Research Institute Problem Solver) representation and the split planning method. In addition, we applied a state-partitioning technique to the backward split planning method to reduce computational time. By analyzing the obtained graph, the planning system decomposes an original planning problem into several independent sub-problems, and then, the planning system generates a proper sequence of actions. To show the effectiveness of the proposed system, we deal with a scenario of a planning problem in the ISH.

• 한국측량학회지
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• 제30권6_2호
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• pp.593-605
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• 2012

LiDAR systems provide dense and accurate topographic information. A pre-requisite to achieving the potential accuracy of LiDAR is having a proper system calibration, which aims at estimating all the systematic errors in the system measurements and the mounting parameters relating the different components. This paper presents a rigorous and two approximate methods for LiDAR system calibration. The rigorous approach makes use of the LiDAR equation and the system raw measurements. The approximate approaches utilize simplified LiDAR equations using some assumptions, which allow for less strict requirements regarding the raw measurements. The first presented approximate method, denoted as quasi-rigorous, assumes that we are dealing with a vertical platform (i.e., small pitch and roll angles). This method requires time-tagged point cloud and trajectory position data. The second approximate method, denoted as simplified, assumes that we are dealing with parallel strips, vertical platform, and minor terrain elevation variations compared to the flying height above ground. Such method can be performed using the LiDAR point cloud only. Experimental results using a real dataset, whose characteristics deviate to some extent from the utilized assumptions in the approximate methods, are presented to provide a comparative analysis of the outcome from the introduced methods.

• Steel and Composite Structures
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• 제25권1호
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• pp.35-43
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• 2017

This paper presents the findings of experimental and numerical investigations on failure analysis and structural behavior of notched steel I-beams reinforced by bonded Carbon Fiber Reinforced Polymer (CFRP) plates under static load. To find solutions for preventing or delaying the failures, understanding the CFRP failure modes is beneficial. One non-strengthened control beam and four specimens with different deficiencies (one side and two sides) on flexural flanges in both experimental test and simulation were studied. Two additional notched beams were investigated just numerically. In the experimental test, four-point bending method with static gradual loading was employed. To simulate the specimens, ABAQUS software in full three dimensional (3D) case and non-linear analysis method was applied. The results show that the CFRP failure modes in strengthening of deficient steel I-beams include end-debonding, below point load debonding, splitting and delamination. Strengthening schedule is important to the occurrences and sequences of CFRP failure modes. Additionally, application of CFRP plates in the deficiency region prevents crack propagation and brittle failure.

• 대한기계학회논문집A
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• 제30권4호
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• pp.364-372
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• 2006

In this paper, we present a finger tip tactile sensor which can detect contact normal force as well as slip. The sensor is made up of two different materials, such as polyvinylidene fluoride (PVDF) known as piezoelectric polymer, and pressure variable resistor ink. In order to detect slip on the surface of the object, two PVDF strips are arranged along the normal direction in the robot finger tip and the thumb tip. The surface electrode of the PVDF strip is fabricated using silk-screening technique with silver paste. Also a thin flexible force sensor is fabricated in the form of a matrix using pressure variable resistor ink in order to sense the static force. The developed tactile sensor is physically flexible and it can be deformed three-dimensionally to any shape so that it can be placed on anywhere on the curved surface. In addition, a tactile sensing system is developed, which includes miniaturized charge amplifier to amplify the small signal from the sensor, and the fast signal processing unit. The sensor system is evaluated experimentally and its effectiveness is validated.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2002년도 학술발표회 발표논문집
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• pp.417-420
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• 2002

VFS는 침전물, 영양물질, 농약 등이 지표수로 유입하는 것을 감소시킬 수 있는 유용한 BMP이다. VFS의 식생의 종류는 목초, 관목 및 나무가 있으나 우리 나라와 같이 비점원오염 관리를 목적으로 하는 경우에는 목초가 가장 적당한 식생이다. VFS의 효과는 토양특성, 배수면적, 지형과 지변경사, 식생의 품질과 토지이용과 기후에 지배된다. 그리고 주기적인 VFS의 관리는 비점원오염을 관리하는데 중요한 요소이다. 식생의 정화능력을 이용한 VFS는 비점원오염 관리에 매우 효과적인 것으로 밝혀지고 있다. 그러나 VFS 독자적인 적용보다는 저류지와 같은 다른 기법과 동시에 적용하는 복합적인 관리대책을 강구하는 것이 더 효과적이다. VFS의 폭은 토양 특성, 배수면적, 지면 경사, 식생의 종류, 토지 이용도 등에 따라서 다르나 대체로 10m 정도가 적당할 것으로 사료된다. 그러나 보다 신뢰성 있는 VFS의 설계기준은 실제 시공과 사후 효과분석을 통하여 많은 자료를 축적한 후에 얻을 수 있을 것이다.

• 대한조선학회논문집
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• 제33권3호
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• pp.22-34
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• 1996

본 논문에서는 선상가열에 의한 평판의 굽힘변형과 관련하여 열탄소성보의 잔류변형과 잔류음력의 분포를 예측하기 위한 간이 수치해석을 시도하였다. 3차원 평판의 거동을 2차원 보의 변형으로 단순화시키기 위하여 수정된 스트립 모델을 사용하고 여기에 유한요소법을 사용하여 시간의 변화에 따른 열탄소성보의 거동을 간편하게 계산할 수 있는 PC용 전산프로그램을 개발하였다. 본 해석에서는 온도장을 구하는 과정은 생략하였고 이미 주어진 온도분포를 사용하여 열변형이 발생하는 문제만을 다루고 있으며 온도에 따른 재료특성치의 변화도 고려하였다. 본 프로그램의 검증을 위하여 계산결과는 기발표된 실험결과나 유사한 방법의 수치해석 결과와 비교하였다.

• 한국구조물진단유지관리공학회 논문집
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• 제3권2호
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• pp.199-204
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• 1999

최근에 복합재료는 콘크리트, 집성보와 같은 기존의 구조재를 보강하여 성능을 향상시킬 목적으로 적용되고 있다. 특히, 대규모의 집성보 구조물은 춤이 큰 부재를 필요로 하는데 섬유보강판을 이용하여 보의 상하부를 보강하면 춤을 크게 하지 않고도 보의 강도와 강성을 증가시킬 수 있다. 본 연구에서는 집성보에 유리섬유보강 플라스틱판(GFRP)을 붙여 스팬 중앙에 집중하중을 가한 휨실험을 수행하였고 실험결과를 층간이론을 이용한 수치해석법과 비교하였다.

• 한국전자통신학회논문지
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• 제7권3호
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• pp.465-473
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• 2012

본 논문은 WLAN/WiMAX 시스템에 적용 가능한 이중대역 평면형 모노폴 안테나를 설계, 제작 및 측정하였다. 제안된 안테나는 2개의 훅크 모양의 선로, 비대칭 접지면 그리고 접지면에 사각 슬릿을 갖도록 설계하였다. 측정과 시뮬레이션 결과사이의 데이터가 잘 일치하고 있는 데이터를 얻었으며 -10dB 임피던스 대역폭을 기준으로 WLAN과 WiMAX 대역을 동시에 만족하고 있음을 확인하였다. 또한 2D 그리고 3D 방사패턴과 이득에 측정결과가 제시되고 논의되었다.