• 대한수학회보
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• 제33권4호
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• pp.503-512
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• 1996

In this paper we investigate a relation between the multiplicity of solutions and source terms in a nonlinear suspension bridge equation in the interval $(-\frac{2}{\pi}, \frac{2}{\pi})$, under Dirichlet boundary condition $$ (0.1) u_{tt} + u_{xxxx} + bu^+ = f(x) in (-\frac{2}{\pi}, \frac{2}{\pi}) \times R, $$ $$ (0.2) u(\pm\frac{2}{\pi}, t) = u_{xx}(\pm\frac{2}{\pi}, t) = 0, $$ $$ (0.3) u is \pi - periodic in t and even in x and t, $$ where the nonlinearity - $(bu^+)$ crosses an eigenvalue $\lambda_{10}$. This equation represents a bending beam supported by cables under a load f. The constant b represents the restoring force if the cables stretch. The nonlinearity $u^+$ models the fact that cables expansion but do not resist compression.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.1082-1086
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• 2004

Since the sheet forming of Mg alloy has many difficulties due to the low formability, many forming conditions need to be selected properly. Especially, the process variables should be investigated to increase the formability, such as, forming temperature. In this paper, the effects of forming process variables has been investigated using the bending and deep drawing process. A simple U-bending designed for mobile part could be formed in room temperature and springback amounts are surveyed. On the other hand, square cup part couldn't be formed in room temperature due to the low formability. Therefore, the effects of forming temperature are investigated in deep drawing process for square cup part. As a experimental and FEM results, the optimum forming temperature is presence and formability in a higher temperature is less than that of lower temperature. Above experimental results are compared with the FEM analysis and well coincided with the experimental results. Therefore, more detail investigations could be progressed to select more appropriate process conditions by the FEA.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2006년도 춘계학술대회 논문집
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• pp.281-284
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• 2006

Metallic sandwich plates with hi-directional inner structure are important new structures for forming applications. Bi-directional corrugated inner structures with less than 25% of relative density are fabricated by piecewise sectional forming process and then bonded with two face sheets by adhesive bonding. Drawing and U-bending experiments have performed and shown that the radius of curvature of sandwich plates is 75mm and sandwich plates are bended 90 degrees without collapse of inner structures. Bi-directional inner structures are suggested to improve formability of sandwich plates for bending and drawing.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1996년도 가을 학술발표회 논문집
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• pp.495-500
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• 1996

In this paper, it is the effect of using fiber sheet (Carbon Fiber Sheet & Aramid Fiber Sheet) and Steel Plate for reinforced concrete beam, 25 specimens are tested, 16 specimens for bending capacity and the other are for shear capacity. In the case of bending testing, the kind and quantity of the reinforcement materials, the bondage and the existence of crack were selected as experimental variables. And in the case of shear testing, it is testified the effect of reinforcement with the variables of the method of reinforcement (side type and U type). As a result, using the reinforcement meterials can increase the capacity of bending stress.

• 한국구조물진단유지관리공학회 논문집
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• 제1권1호
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• pp.65-73
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• 1997

In this paper, It is the effect of using fiber sheet (Carbon Fiber Sheet & Aramid Fiber Sheet) and Steel Plate for reinforced concrete beam. 25 specimens are tested, 16 specimens are for bending capacity and the other are for shear capacity. In the case of bending testing, the kind and quantity of the reinforcement materials, the bondage and the existence of crack were selected as experimental variables. In the case of shear testing, It is testified the effect of reinforcement with the variables of the method of reinforcement (side type and U type). As a result, Using the reinforcing materials can increase the capacity of bending and shear stress.

• 대한기계학회논문집A
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• 제31권4호
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• pp.425-431
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• 2007

[ $Al_2O_3/SiC$ ]composite ceramics were sintered to evaluate the bending strength and elastic wave characteristics. The three-point bending test was carried out under room temperature. The elastic wave was detected by fracture wave detector. The crack healing behavior was investigated from 1373 K to 1723 K. The bending strength of $Al_2O_3/SiC$ composite by nanocomposite is higher than that of $Al_2O_3$ monolithic. Crack-healing behavior depended on an amount of additive powder $Y_2O_3$. In $Al_2O_3/SiC$ composite ceramics with 3 wt. % $Y_2O_3$ for additive powder, the bending strength at 1573 K is about 100% increase than that of the smooth specimens. From the result of wavelet analysis of elastic wave signal, the smooth specimen and heat treated specimen of $Al_2O_3$ monolithic and $Al_2O_3/SiC$ composite ceramics showed characteristics of frequency about 58 kHz. The strength of $Al_2O_3/SiC$ composite ceramics was a little higher than those of $Al_2O_3$ monolithic. The dominant frequencies were high with increasing of $Y_2O_3$ for additive powder. The dominant frequencies had direct connection with the bending strength.

• Structural Engineering and Mechanics
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• 제31권4호
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• pp.383-392
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• 2009

The static and dynamic analyses of simply supported beams are studied by using the U-transformation method and the finite difference method. When the beam is divided into the mesh of equal elements, the mesh may be treated as a periodic structure. After an equivalent cyclic periodic system is established, the difference governing equation for such an equivalent system can be uncoupled by applying the U-transformation. Therefore, a set of single-degree-of-freedom equations is formed. These equations can be used to obtain exact analytical solutions of the deflections, bending moments, buckling loads, natural frequencies and dynamic responses of the beam subjected to particular loads or excitations. When the number of elements approaches to infinity, the exact error expression and the exact convergence rates of the difference solutions are obtained. These exact results cannot be easily derived if other methods are used instead.

• 한국해양공학회지
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• 제5권2호
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• pp.225-225
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• 1991

• 한국광학회:학술대회논문집
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• 한국광학회 2006년도 하계학술발표회 논문집
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• pp.181-182
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• 2006

• Restorative Dentistry and Endodontics
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• 제33권4호
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• pp.323-331
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• 2008

이 연구의 목적은 세가지 니켈-티타늄 파일의 휨과 회전 조건 하에서의 응력 분포를 유한요소 모형을 이용하여 비교하는 것이다. ProFile .06/#30, ProTaper와 ProTaper Universal의 F3파일을 마이크로컴퓨터 단층촬영을 하고 reverse engineering을 통하여 세 니켈 티타늄 파일의 구조를 얻고 삼차원 유한요소모형을 제작하였다. 니켈 티타늄 합금의 비선형적인 물리적 성질을 반영하고 ABAQUS 프로그램을 이용하여 휨과 회전 조건 하에서의 기계적인 움직임을 수학적으로 예측 분석하였다. U-형태의 단면 구조를 가진 ProFile이 모형 가운데 가장 좋은 휨 성질을 나타냈다. 동일한 휨량 조건에서는 볼록한 삼각형 단면의 ProTaper가 다른 모형보다 많은 힘을 필요로 하였으며, 반면에 가장 높은 von Mises 응력은 ProTaper Universal의 단면에서 움푹 파인 부위에 집중되었다. ProFile 모형은 동일한 크기의 회전력 에 대해 가장 큰 응력 집중을 U-형 구 부위에 나타냈다. ProTaper 모형은 다른 모형에 비해 동일량을 비틀기 위해 더 많은 힘을 필요로 하였으며, 반면에, 동량의 비틀림에서는 가장 높은 von Mises 응력이 ProTaper Universal의 단면에서 움푹 파인 부위에 집중되었다.