• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.492-497
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• 2002

In this paper, Power Flow Analysis(PFA) method has been applied to the prediction of vibration energy density and intensity of coupled shell structures in the medium-to-high frequency ranges. To consider the wave transformation at joint between shell elements, power transmission and reflection coefficients are investigated for various joint angles, and here Donnell-Mushtari thin shell theory has been used. For validations computations are performed to analyze the response of coupled shells by changing the excitation frequency and damping loss factor.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.2
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• pp.25-34
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• 2003

In the present paper, formulation of a nine-node assumed strain shell element is modified and extended for analysis of actuator embedded/attached structures. The shell element can alleviate locking and has sic DOFs per node by discarding assumption of no thickness change. In modeling of the physicalquantities, we have assumed linear strain field through the whole thickness direction. The electric and mechanical quantities have been coupled through the constitutive equations. Unlike typical shell element, the present shell element allows thickness change. Thus, three-dimensional piezoelasticity can be accurately simulated. Base on the formulation, a finite element program is generated and the code is validated by solving numerical examples. The results from the present work are well agreed with those from other references.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1994.10a
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• pp.975-979
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• 1994

The experimental and finite element studies of a coaxial cylindrical shell filled with liquid in the annular gap were performed to understand its vibration characteristics. Finite element analysis was achieved by using ANSYS code. Form the investigation of the changing trend of natural frequencies for the change of annular gap we know that the natural frequency of the coaxial cylindrical shell varies according to the mode shape. that is, in case of in-phase mode the natural frequency decrease as annular gap increase, but in case of out-of-phase mode the natural frequency increase. Finite element analysis results show the excellent agreement with the experimental results both in air and in water case, so that analysis on other cases with be possible without experiment.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.352.2-352
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• 2002

In this paper, Power Flow Analysis (PFA) method has been applied to the prediction of vibration energy density and intensity of coupled shell structures in the medium-to-high frequency ranges. To consider the wave transformation at joint between shell elements, power transmission and reflection coefficients are investigated for various joint angles, and here Donnell-Mushtari thin shell theory has been used. (omitted)

• Journal of the Society of Naval Architects of Korea
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• v.29 no.2
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• pp.103-114
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• 1992

A study result of buckling reliability is presented for the axially compressed imperfect elastic cylinder. Multi-mode analysis program is developed from Karman-Donnell Equation for the calculation of the buckling load of the cylindrical she1l. Geometric intial imperfection is approximated by double Fourier series of which coefficients are assumed random variables with jointly normal distribution characteristics. Crude Monte Carlo simulation technique is used to calculate the probabilistic failure properties of several cases with various imperfection Conditions.

• Journal of Korean Society of Steel Construction
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• v.26 no.3
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• pp.219-229
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• 2014

The experiment and FE analysis of ultimate behavior of GFRP cylindrical shell structure stiffened by steel pipe ring instead of rectangular cross-section ring was presented. Four kinds of test models were designed and flexural failure experiment was performed to investigate ultimate behavior characteristic according to the size of cross section of steel pipe ring and diameter of GFRP shell. Material properties of specimens were experimented by bending, tensile and compressive test. Displacements and strains were measured to evaluate failure behavior of steel pipe ring and GFRP shell structure. The experimental results were compared with the FEA results by commercial program ABAQUS. It is observed that GFRP shell structure stiffened by steel ring have enough ductility to bending failure, and an increase of bending rigidity of steel ring is very effective to increase of failure strength of GFRP shell structure.

• Journal of the Korea Concrete Institute
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• v.22 no.6
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• pp.741-751
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• 2010

An experimental study was performed to investigate the earthquake resistance of the beam-column connections as a part of a precast concrete moment-resisting frame that uses precast concrete U-shaped shells for the beams. Five full-scale precast concrete specimens and one conventional monolithic concrete specimen were tested under cyclic loading. The parameters for this test were the reinforcement ratio, stirrup spacing, and end-strengthening details of the precast beam shell. The test results showed that regardless of the test parameters, the precast concrete beam-column connections showed good load-carrying capacity and deformation capacity, which were comparable to those of conventional monolithic concrete specimen. However, at large deformations, the beam-column connections of the precast concrete specimens were subjected to severe strength degradation due to diagonal shear cracks and the bond-slip of re-bars at the joint region. For this reason, the energy dissipation capacity and stiffness of the precast concrete specimens were significantly less than those of the cast-in-place specimen.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.1
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• pp.39-46
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• 2013

Smart material such as SMA (Shape Memory Alloy) has been studied in various ways because it can perform continuous, flexible, and complex actuation in simple structure. Smart soft composite (SSC) was developed to achieve large deformation of smart material. In this paper, a shell actuator using woven type SSC was developed to enhance stiffness of the structure while keeping its deformation capacity. The fabricated actuator consisted of a flexible polymer and woven structure which contains SMA wires and glass fibers. The actuator showed various actuation motions by controlling a pattern of applied electricity because the SMA wires are embedded in the structure as fibers. To verify the actuation ability, we measured its maximum end-edge bending angle, twisting angle, and actuating force, which were $103^{\circ}$, $10^{\circ}$, and 0.15 N, respectively.

• Journal of the Earthquake Engineering Society of Korea
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• v.6 no.2
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• pp.9-19
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• 2002

Steel piers and concrete-filled steel(CFS) piers, in spite of reasonable strength, high ductility, small section, and fast construction, have not been considered as one of alternatives to RC piers even in the highly populated urban area where aseismic safety, limited space and fast construction are indispensably required. This paper, the first of two companion papers for the seismic performance of steel and CFS piers, tests steel and CFS piers under quasi-static cyclic loading to estimate their ductility and strength. Additional details such as rebars and base ribs are added to increase the ductility of a concrete-filled steel pier with minimum additional cost. Also, simplified numerical analyses using nonlinear spring and shell elements are examined for the estimation of the ductility and strength of concrete-filled steel piers and a steel pier. The result shows that concrete-filled steel peirs have higher energy absorption, i.e., ductility and strength than those of steel pier and increasing bonding between in-filled concrete and lower diaphragm, and the improved details of stress concentrated region would be important for the ductility and strength of a pier. Numerical results show that simplified modeling with nonlinear springs and shells has potential to be effective modeling technique to estimate the seismic performance of a concrete-filled steel pier.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.211-214
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• 2010

플랫 플레이트 시스템은 기둥 주위의 국부적인 응력집중 현상으로 인한 뚫림전단 파괴에 대해 취약하다. 따라서 유한요소해석을 통해 이러한 플랫 플레이트 시스템의 뚫림전단 성능을 평가하고자 한다. 슬래브의 전단을 고려하기 위하여 Reissner-Mindlin 가정을 바탕으로 한 등매개변수 감절점 쉘 요소를 적용하였다. 콘크리트의 재료적 비선형 거동을 고려하기 위해 압축거동은 수정압축장 이론을 적용하였으며 인장강성효과 또한 콘크리트 재료모델에 반영하였다. 기존 실험결과와의 비교를 통해 타당성을 검증하고자 하였다. 비교 결과, 약 16%의 오차율을 보였으며 보강비가 낮은 실험체에 비해 보강비가 높은 실험체가 실험결과에 가까운 값을 예측하는 것으로 나타났다.