• Computers and Concrete
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• 제31권3호
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• pp.267-276
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• 2023

The main purpose of the current research is to develop an efficient two variables trigonometric shear deformation beam theory to investigate the buckling behavior of symmetric and non-symmetric functionally graded carbon nanotubes reinforced composite (FG-CNTRC) beam resting on an elastic foundation with various boundary conditions. The proposed theory obviates the use to shear correction factors as it satisfies the parabolic variation of through-thickness shear stress distribution. The composite beam is made of a polymeric matrix reinforced by aligned and distributed single-walled carbon nanotubes (SWCNTs) with different patterns of reinforcement. The material properties of the FG-CNTRC beam are estimated by using the rule of mixture. The governing equilibrium equations are solved by using new analytical solutions based on the Galerkin method. The robustness and accuracy of the proposed analytical model are demonstrated by comparing its results with those available by other researchers in the existing literature. Moreover, a comprehensive parametric study is presented and discussed in detail to show the effects of CNTs volume fraction, distribution patterns of CNTs, boundary conditions, length-to-thickness ratio, and spring constant factors on the buckling response of FG-CNTRC beam. Some new referential results are reported for the first time, which will serve as a benchmark for future research.

• 한국광학회지
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• 제23권4호
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• pp.147-153
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• 2012

고정 화소수의 표시소자를 기반으로 하는 무안경 방식 다시점 3D 디스플레이는 시점수 증가에 따른 입체영상 저해상도 문제를 안고 있다. 이를 해결하기 위하여, 본 논문은 프로젝션 기반의 무안경식 다시점 3D 디스플레이 시스템에서 구면 형태의 상용 렌티큐라 렌즈시트를 사용하여 단위화소의 폭을 집속하고 광원수 증가에 따른 유효 해상도를 증가시켜 저해상도의 문제를 해결하는 광학적 접근 방법을 제시하였다. 제시된 방법은 주어진 시스템환경에서 도출 가능한 주요 파라메터의 정의 및 이론적, 실험적 결과를 통하여 축소 가능한 단위화소폭 및 확장 가능한 유효 해상도를 도출하는 수순으로 수행되었다. 결과적으로 1.016 mm의 단위화소폭을 기준으로 25 LPI의 렌티큐라 렌즈 시트를 투과하였을 경우, 축소된 폭(Beam waist)은 0.19 mm, 확장 가능한 유효 해상도는 최대 5배를 나타내었다. 이와 더불어, 초점심도(Depth of focus)는 1.496 mm로서 상용 렌티큐라 렌즈 시트의 두께 허용치 및 광학계 정렬 허용범위를 충분히 확보하였다.

• Radiation Oncology Journal
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• 제10권1호
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• pp.115-120
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• 1992

물팬톰내에 조사된 10 MV X-선의 심부율을 입자의 수송이론을 근거로 한 1차원적인 모델을 이용하여 계산하였다. 계산된 이론식의 매개상수는 9개로 줄일 수 있었으며 실측치를 이용하여 비선형 회귀분석 방법으로 얻을 수 있다. 조사면과 선원간의 거리 및 깊이에따른 3차원적인 흡수선량분포의 계산식은 고에너지 광자선이 조사된 물팬톰내에서의 Beam Profile에 대한 시도함수를 이용하여 수송이론에의한 심부율계산을 3차원적으로 확장하였으며 흡수 선량 분포는 3차원적 위치의 함수로 널리 계산할 수 있다. 이 모델을 사용하여 계산된 이론값은 실험값과 $\pm12\%$ 이내의 만족할만큼 잘 일치하였다.

• 한국안전학회지
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• 제21권1호
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• pp.96-104
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• 2006

This study is to find out how the sawdust-mixed RC beam with holes acts compared to two case of normal one with sawdust without hole, without sawdust. variables are ED3H1, ED3H2, ED3H1UB, ED3H2L, ED5H1, ED5H1UB, ED5H2, ED5H2L, Normal with sawdust PLA without sawdust. All sand, aggregate, cement are in accordance with KS. mixing design is also in accordance with KS and done at D remicon company in order to decrease any error in mixing manually. ED3H1 showed 7tone of maximum load capacity having only minor tensile deformation around hole, compared to the center of the beam. ED5H2L showed almost same shape of tensile strain between hole area and center of two beam length, while having 9.5 tone load capacity, incase of two holes being in the longitudinal axis. But ED5H2 in case of two holes being in same forcing direction showed 8.4tone of load capacity while having minor tensile chape around hole and normal tensile shape in the center of beam length. Two diameter 3cm hole in longitudinal axis give more effective behavior than the other case, practically. Capacity decrease between 5cm and 3cm in eccentric position form the longitudinal axis is less than percents. There is minor capacity difference between hole diameter 3cm hole, but 13tone difference of load capacity between hole diameter 5cm.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2020년도 봄 학술논문 발표대회
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• pp.214-215
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• 2020

The 3D scanning technology is being introduced for quality inspection of building construction. Therefore, this study tried to confirm whether it is possible to check the quality of rebar by using 3D scanning. After rebar placed on the formwork slab was scanned with a 3D scanner, the rebar spacing was confirmed by overlapping with the CAD drawing. As a result, the 3D scanner was able to check the quality of rebar work on one floor at a time. Therefore, 3D scanning could be used for quality inspection of rebar works such as columns, beam and girders, walls, and slabs in the future.

• 방송과미디어
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• 제6권2호
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• pp.84-101
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• 2001

In this paper, we present a primitive system design of a super multi-view(SMV) 3-D display system based on a focused light array(FLA) concept using reflective vibrating scanner array(ViSA). The parallel beam scanning using a vibrating scanner array is performed by moving left and right an array of curvature-compensated mirrors or diamond-ruled reflective grating attached to a vibrating membrane. The parallel laser beam scanner array can replace the polygon mirror scanner which has been used in the SMV 3-D display system based on the focused light array(FLA) concept proposed by Kajiki at TAO(Telecommunications) Advancement Organization). The proposed system has great advantages in the sense that it requires neither huge imaging optics nor mechanical scanning pals. Some mathematical analyses and fundamental limitations of the proposed system are presented. The proposed vibrating scanner array, after some modifications and refinements, may replace polygon mirror-based scanners in the near future.

• Applied Microscopy
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• 제39권4호
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• pp.349-354
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• 2009

TFT-LCD의 구조불량이 발생한 박막 트랜지스터에 대해서 집속이온빔 가공장치(Dual-beam FIB/SEM)를 이용하여 연속절편법(Serial sectioning)과 일련의 연속적인 2차원 주사전자현미경 이미지를 얻었고, IMOD 소프트웨어를 통해서 3차원 구조구현(3D reconstruction) 연구를 하였다. 3차원 구조구현 결과, Gate막과 Data막이 접합되어 있는 불량이 관찰되었다. 두 막이 접합되어서 ON/OFF 역할을 하는 Gate의 기능이 상실되었고, Data신호는 Drain을 통해서 투명전극에 전류를 공급하여 계속 빛나는 선 불량(line defect)이 발생한 것으로 판단된다. 이 논문의 결과인 집속이온빔 가공장치(Dual-Beam FIB/SEM)를 이용한 3차원 구조구현 연구와 연속절편법, 주사전자현미경 이미지작업, 이미지 프로세싱에 대한 결과는 향후 연구의 기초자료로 활용될 수 있을 것으로 판단된다.

• 한국전자통신학회논문지
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• 제4권3호
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• pp.236-242
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• 2009

2관절 유연한 로봇 팔는 관절 축을 회전할 때 진동이 발생한다. 본 논문에서는 유연한 로봇팔의 진동 동력학은 bernoulli-Euler의 beam이론과 라그란지 방정식을 이용하여 구하였고, $\dot{D}$-2C가 skew symmetric이다는 사실을 사용하여 계산량을 줄이는 단순한 구조의 새로운 제어기를 제안한다. Lyapunov 안정도 이론은 관절을 조절하기 위한 안정한 확정적인 비선형 제어기를 성취하기 위하여 적용된다.

• 한국해양공학회지
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• 제23권6호
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• pp.131-135
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• 2009

We present an optimum design method for a rectangular reinforced concrete beam using Genetic Algorithms. The optimum design procedure in this paper employs 2 design cases: i) all of the design variables (b, d, As) of the rectangular reinforced concrete section are used pseudo-continuously, ii) one is pseudo-continuous for the concrete cross section (b, d) and the other is discrete, using an index for the steel area (As). The optimum design in this paper uses Chakrabarty's model. In this paper, the Genetic Algorithms use the method of Elitism and penalty parameters to improve the fitness in the reproduction process, which leads to very practical designs. The optimum design of the steel area in the examples uses ASTM standard reinforcing bars (#3~#11, #14, #18).

• Steel and Composite Structures
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• 제37권1호
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• pp.37-49
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• 2020

In this paper, free vibration finite element analysis of axially moving laminated composite beams subjected to axial tension is studied. It is assumed that the beam has a constant axial velocity and is subject to uniform axial tension. The analysis is based on higher-order theories that have been presented by Carrera Unified Formulation (CUF). In the CUF technique, the three dimensional (3D) displacement fields are expressed as the approximation of the arbitrary order of the displacement unknowns over the cross-section. This higher-order expansion is considered in equivalent single layer (ESL) model. The governing equations of motion are obtained via Hamilton's principle. Finally, several numerical examples are presented and the effect of the ply-angle, travelling speed and axial tension on the natural frequencies and beam stability are demonstrated.