• 한국공간구조학회논문집
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• 제15권1호
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• pp.57-64
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• 2015

This paper shows the test results of continuous reinforced concrete beams with external post-tensioning rods. Six three-span beams were prepared and tested to fail. Three beams were designed to have flexure-dominating behavior and the others to have shear-critical behavior. In each group, one beam without external post-tensioning rods was designated as a control beam and two beams had the external post-tensioning rods of 18 mm or 22 mm diameter. External post-tensioning rods were installed within an interior span of 6000 mm. They show V-shaped configuration because two anchorages were located at the top of interior supports and a saddle pin at mid-span was installed at the bottom of the beam. Test results show that the load and shear capacities of strengthened beams were increased when compared with the control beam. Additionally, the measured shear strength was compared with the strength predicted by ACI 318-11 code equations. The detailed ACI 318-11 equation predicted the measured shear strength and failure location of the continuous beam reasonably well.

• 한국공간구조학회논문집
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• 제19권3호
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• pp.69-76
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• 2019

A Beam String Structure (BSS) is a type of hybrid structures, which is composed of upper structural members, lower strings, and struts. Due to the advantages that the pre-tensioned strings elicit pre-caber of the upper structural members, the deflection can be greatly reduced without increasing the structural member size. In this study, a two-way beam string structure is proposed to endure bi-directional loading. The two-way beam string structure consists of two cable parts, namely, sagging and arch-shaped cables. A parametric study is presented aimed at proposing design guide lines of the two-way beam string structures. Numerical finite element analyses through the ABAQUS package were implemented to obtain their behaviors.

• 한국광학회:학술대회논문집
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• 한국광학회 2007년도 하계학술발표회 논문집
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• pp.151-152
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• 2007

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 춘계학술대회 논문집
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• pp.377-378
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• 2012

• 한국의학물리학회지:의학물리
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• 제1권1호
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• pp.109-122
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• 1990

전자선 치료에 있어서 조사면을 부분적으로 차폐할 수 있는 차폐체 제작 방법을 제시하였다. Lipowitz 합금으로 만든 차폐체는 표준 Siemens cone에 적합하며, 조사면의 평탄도는 차폐체에 의한 영향을 거의 받지 않았다. 그러나 개방 조사면에 대한 차폐 조사면의 비가 0.7 이상이면 차폐체에 의한 선량의 차이가 있음을 알았다. Biggs 등이 제안한 Cone ratio는 차폐 조사면의 Cone ratio curve가 개방조사면의 Cone ratio를 따르지 않기 때문에 본 연구에서는 Cone ratio를 Cone factor와 Insert ratio로 나누어 차폐 조사면에 대한 선량 변화를 넓게 측정하였다.

• Macromolecular Research
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• 제16권5호
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• pp.434-440
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• 2008

Three-armed, star-shaped molecules containing 4-(N,N-diphenyl)amino-4'-nitroazobenzene chromophores were synthesized to study the diffraction behavior after inscribing surface relief gratings. The two molecules differed in terms of their mode of chromophore attachment to the core. In compound 5, they were bound to the core laterally through alkylene spacers, whereas the chromophores were tethered perpendicularly to the core in compound 4. Although 60 wt% of the polar azobenzene chromophores was comprised of large molecules, no aggregation behavior was observed in the absorption spectra of the thin films. The surface relief gratings were elaborated on the surface of the molecular films by the two-beam interference method. The dynamics of grating formation were studied in terms of the diffraction efficiency using two different film samples made up of two star-shaped molecules. The maximum diffraction efficiency of D-$(ENAZ)_3$, compound 4, was measured to be about 30%, which was significantly high. The mode of chromophore attachment affected the dynamic properties of the diffraction gratings.

• Steel and Composite Structures
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• 제27권3호
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• pp.337-353
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• 2018

In previous weak-axis moment connection tests, brittle fracture always initiated near the edge of the beam flange groove weld due to force flow towards the stiffer column flanges, which is the opposite pattern as strong-axis moment connections. As part of the China NSFC (51278061) study, this paper tested two full-scale novel weak-axis reduced beam section moment connections, including one exterior frame connection specimen SJ-1 under beam end monotonic loading and one interior frame joint specimen SJ-2 under column top cyclic loading. Test results showed that these two specimens were able to satisfy the demands of FEMA-267 (1995) or ANSI/AISC 341-10 (2010) without experiencing brittle fracture. A parametric analysis using the finite element software ABAQUS was carried out to better understand the cyclic performance of the novel weak-axis reduced beam section moment connections, and the influence of the distance between skin plate and reduced beam section, a, the length of the reduced beam section, b, and the cutting depth of the reduced beam section, c, on the cyclic performance was analyzed. It was found that increasing three parametric values reasonably is beneficial to forming beam plastic hinges, and increasing the parameter a is conducive to reducing stress concentration of beam flange groove welds while increasing the parameters b and c can only reduce the peak stress of beam flange groove welds. The rules recommended by FEMA350 (2000) are suitable for designing the proposed weak-axis RBS moment connection, and a proven calculation formulation is given to determine the thickness of skin plate, the key components in the proposed weak-axis connections. Based on the experimental and numerical results, a design procedure for the proposed weak-axis RBS moment connections was developed.

• Structural Engineering and Mechanics
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• 제63권5호
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• pp.617-628
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• 2017

In order to study the failure mode and seismic behavior of the interior-joint in steel traditional-style buildings, a single beam-column joint and a double beam-column joint were produced according to the relevant building criterion of ancient architectural buildings and the engineering instances, and the dynamic horizontal loading test was conducted by controlling the displacement of the column top and the peak acceleration of the actuator. The failure process of the specimens was observed, the bearing capacity, ductility, energy dissipation capacity, strength and stiffness degradation of the specimens were analyzed by the load-displacement hysteresis curve and backbone curve. The results show that the beam end plastic hinge area deformed obviously during the loading process, and tearing fracture of the base metal at top and bottom flange of beam occurred. The hysteresis curves of the specimens are both spindle-shaped and plump. The ultimate loads of the single beam-column joint and double beam-column joint are 48.65 kN and 70.60 kN respectively, and the equivalent viscous damping coefficients are more than 0.2 when destroyed, which shows the two specimens have great energy dissipation capacity. In addition, the stiffness, bearing capacity and energy dissipation capacity of the double beam-column joint are significantly better than that of the single beam-column joint. The ductility coefficients of the single beam-column joint and double beam-column joint are 1.81 and 1.92, respectively. The cracks grow fast when subjected to dynamic loading, and the strength and stiffness degradation is also degenerated quickly.

• Radiation Oncology Journal
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• 제20권3호
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• pp.274-282
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• 2002

목적 : 방사선치료시 환자에 조사되는 방사선량을 매 치료시마다 간편하게 확인하기 위한 생체내(in vivo) 선량측정의 한 방법으로 투과선량을 이용하는 새로운 시스템에 필요한 알고리즘을 이미 개발한 바 있다. 본 연구에서는 조사면 일부가 차폐된 부정형 조사면에서 적용하기 위한 보정 알고리즘을 개발하고자 하였다. 재료 및 방법 : 알고리즘을 개발하기 위한 기본 자료를 마련하기 위하여 투과선량 측정을 시행하였다. 측정에는 선형가속기의 6 MV 및 10 MV의 X선을 이용하였고, 이온함형 측정기 및 전위계를 사용하였다. 측정조건으로는 조사면의 크기(collimator opening)는 $2\times2\;cm^2$에서 $32\times32\;cm^2$까지 한 변을 2 cm씩 증가시켜 16단계로 하였고, 팬톰 두께(phantom thickness; Tp)는 0, 10, 20 및 30 cm, 팬톰과 측정기간의 거리(phantom chamber distance; PCD)는 10, 30 및 50 cm으로 하였다. 이 때 조사면의 일부를 차폐하였으며 차폐되지 않은 유효조사면(effective field size)의 크기를 $5\times5,\;10\times10,\;15\times15$ 및 $20\times20\;cm^2$으로 하였다. 결과 : 조사면의 일부가 차폐체에 의하여 차폐된 경우 종양선량이 감소되며 동시에 투과선량도 감소된다는 물리학적인 추론을 이용하여 방사선조사면 일부 차폐가 투과선량에 미치는 영향을 보정하기 위한 알고리즘을 개발하였으며 조사면 일부가 차폐된 여러 측정 조건에서 알고리즘을 이용한 계산치와 실제측정치 간의 오차는 ${\pm}1.0\%$ 이내이었다. 결론 : 투과선량 계산 알고리즘은 조사면 일부가 차폐된 불규칙 조사면의 경우 ${\pm}1.0\%$ 이하의 오차 범위로 정확히 투과선량을 계산할 수 있음을 확인하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제32권2호
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• pp.250-255
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• 2008

Springs are widely utilized in machine element. To find out stiffness of frustum-shaped coil spring, the space beam theory using the finite element method is adopted in this paper. In three dimensional space, a space frame element is a straight bar of uniform cross section which is capable of resisting axial forces, bending moments about two principal axes in the plane of its cross section and twisting moment about its centroidal axis. The corresponding displacement degrees of freedom are twelve. To find out load vector of coil spring subjected to distributed compression. principle of virtual work is adapted. And this theory was programming using MATLAB software. To compare FEM using MATLAB software was applied MSC. Nastran software. The geometry model for MSC. Patran was produced by 3-D design modeling software. Finite element model was produced by MSC. Patran. Finite element was applied tetra (CTETRA) having 10 node. The analysis results of the MATLAB and MSC. Nastran are fairly well agreed with those of various experiments. Using MATLAB program proposed in this paper and MSC. Nastran, spring constants and stresses can be predicted by input of few factors.