• Current Optics and Photonics
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• 제4권4호
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• pp.267-272
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• 2020

The propagation of a truncated Airy beam with spatial phase modulation (SPM) is investigated in Kerr nonlinearity with an optical lattice. Before the truncated Airy beam enters the optical lattice, a sinusoidal phase is introduced on the wave-front of the beam. The effect of the spatial phase modulation and optical lattice on propagation behavior is analyzed by direct numerical simulation. It is found that the propagation direction of a truncated Airy beam can be effectively controlled by adjusting the values of phase shift. The effects of optical amplitude, truncation factor, spatial modulation frequency, lattice period and lattice depth on the propagation are discussed in detail. By choosing a high modulation depth, the finite-energy Airy beam can be deflected with a large deflection angle in an optical lattice.

• 대한방사선치료학회:학술대회논문집
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• 대한방사선치료학회 1997년도 학술대회
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• pp.10-11
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• 1997

• 대한방사선치료학회지
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• 제9권1호
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• pp.37-39
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• 1997

• 대한조선학회논문집
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• 제44권1호
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• pp.26-31
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• 2007

Understanding viscoelastic properties of composite materials is essential for the design and analysis of composite structures. Specially, the loss factor and Young's modulus must be known to develop finite element codes for a composite structure with several damping materials. In this study, an advanced technique for obtaining accurate loss factor and Young's modulus of a composite structure is introduced based on the method of American Society for Testing and Materials (ASTM). The loss factor and Young's modulus of a composite structure are measured for different temperatures by performing the test in a vibration measurement room where temperature can be controllable from 5 to 45 Celsius.

• Composites Research
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• 제12권2호
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• pp.26-35
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• 1999

모달변형에너지법과 조화진동해석법을 이용하여 겹침이음부와 부분층댐버를 갖는 보에 대해 유한요소모델을 설정하고 진동감쇠특성을 연구하였다. 모달변형에너지법과 조화진동해석법으로 구한 계의 공진주파수와 손실계수는 거의 같은 값ㅇ르 보였으며, 형상의 변화에 따른 손실계수 변동경향은 이론해석에 의한 결과와 유사하였다. 부분층댐퍼의 위치, 점탄성층과 보강탄성층의 두께 및 탄성계수의 변화가 계의 손실계수에 미치는 영향을 파악하였으며, 점탄성층의 손실계수변화에 따른 영향도 검토하였다. 이들 결과로부터 계의 감쇠효과를 극대화하기 위한 구조물의 형상 및 물성조건을 제시하였다.

• Coupled systems mechanics
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• 제12권2호
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• pp.151-165
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• 2023

In this study, a simple method for the determination of the shear correction factor for composites beam with a rectangular cross section is presented. The plane stress elasticity assumption is used after simplifications of the expression of the stress distribution in the beam. The different fiber orientation angle and volume fraction are considered in this work. The studied structure is subjected to various loading type (thermal and hygrothermal). The numerical results obtained show that there is a dependence of the shear coefficient on the orientation of the fibers. The evolution of the shear correction factors depends not only on the orientation of the fibers and also on the volume fraction and the environment. the advantage of this developed formula of the shear correction factor is to obtain more precise results and to consider several parameters influencing this factor which are neglected if the latter is constant.

• Steel and Composite Structures
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• 제21권2호
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• pp.343-356
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• 2016

As the common cast-in-place construction works fails to meet the enormous construction demand under rapid economic growth, the development of prefabricated structure instead becomes increasingly promising in China. For the prefabricated structure, its load carrying connection joint play a key role in maintaining the structural integrity. Therefore, a novel end plate bolt connecting joint between fully prefabricated pre-stressed concrete beam and high-strength reinforcement-confined concrete column was proposed. Under action of low cycle repeated horizontal loadings, comparative tests are conducted on 6 prefabricated pre-stressed intermediate joint specimens and 1 cast-in-place joint specimen to obtain the specimen failure modes, hysteresis curves, skeleton curves, ductility factor, stiffness degradation and energy dissipation capacity and other seismic indicators, and the seismic characteristics of the new-type prefabricated beam-column connecting joint are determined. The test results show that all the specimens for end plate bolt connecting joint between fully prefabricated pre-stressed concrete beam and high-strength reinforcement-confined concrete column have realized the design objectives of strong column weak beam. The hysteretic curves for specimens are good, indicating desirable ductility and energy dissipation capacity and seismic performances, and the research results provide theoretical basis and technical support for the promotion and application of prefabricated assembly frames in the earthquake zone.

• 한국가구학회지
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• 제21권1호
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• pp.26-39
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• 2010

This is a leading study to replace the structural analysis methodology on the specific traditional joint by a numerical analysis. Tests were carried out to test the compressive methodologies with the numerical results. The Japanese larch was used as a sample. The Orthotropic property of wood was specifically considered for the finite element numerical analysis. Linear numerical analysis and non-linear numerical analysis for the BEAM element and the two SOLID elements of ANSYS were used to analyze the compressive performance. In addition, more finely divided elements were used to raise the accuracy of the numerical result. Finally, the statistically significant differences were tested between that of the analytical and numerical results. It could be concluded that the SOLID 64 element shows the most optimum result when the non-linear analysis with the more finely divided element was used. However, finely dividing of the element is a considerable time consuming process, and it is quite difficult to raise the accuracy of the non-linear numerical analysis. Therefore, if considering the vertical displacement to be of the only interest, the BEAM element is more efficient than the SOLID element because the BEAM element is reflected as a simple line, which is less time consuming and difficult in dividing the elements. But, the BEAM element cannot accurately model the knot as a strength defect factor which is an important property in the orthotropic property of wood. Therefore, the SOLID element should be used to model the strength defect factor, knot, as it can be efficiently applied on the structural size flexure member which could be more strongly effected by the knot. In addition, it is useful at times when the failure types of members are to be more closely investigated, as the SOLID element is able to examine the local stress distribution of the member. The conclusion drawn by this study is of the good concordance between analytical results and numerical results of compressive wood members, but how orthotropic properties should only be considered. The numerical analysis on the specific Korean traditional joints will be based on the current study results.

• 한국터널지하공간학회 논문집
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• 제14권1호
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• pp.55-77
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• 2012

현대식 Rock TBM공법은 TBM에 의한 굴착과 지반 타입에 따른 능동적인 지보가 어우러진 공법으로 세그먼트를 사용하지 않고 숏크리트, 링빔, 록볼트, 와이어매쉬 등의 지보재에 의해 터널을 지보한다. 현대식 Rock TBM에서 사용되는 링빔은 H-형강을 사용하여 NATM의 강지보재와 유사하나 원형으로 완전히 폐합되어 설치됨에 따라 강지보재보다 더 효과적이다. 따라서 현대식 Rock TBM에서 링빔은 터널의 안정성 향상에 기여하는 바가 크며, 본 연구에서 소개하는 가압형 링빔(pressurized ring beam)은 그 효과를 더욱 향상 시킬 수 있다. 가압형 링빔의 효과를 검증하기 위해 3차원 수치해석을 수행하였으며 그 결과 최소주응력 증가, 과대변위를 발생시키는 소성변형률의 감소, 링빔 설치 후 발생하는 변위인 상대변위감소 그리고 링빔 간격 증가 효과를 확인하였다.

• 한국강구조학회 논문집
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• 제18권5호
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• pp.535-542
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• 2006

본 논문에서는 압연형강(H형강)을 이용한 강합성 교량에 대한 3차원 유한요소 해석을 실시하여, 가로보가 활하중 횡 분배에 미치는영향에 대해 검토하였다. 고려된 주요 변수는 주형과 가로보의 단면2차모멘트비, 가로보의 설치 여부, 가로보의 개수 등이다. 유한요소 해석을 통한 활하중 횡분배 계수와 함께 관용적인 격자해석에 의한 활하중 횡분배 계수도 비교하였다. 분석결과에서 가로보는 활 하중 횡분배에 별다른 영향을 미치지 못하며, 콘크리트 바닥판이 활하중 횡분배에는 가장 중요한 역할을 하는 것으로 나타났다. 따라서 활하중 횡분배를 목적으로 설치하는 가로보는 제거가 가능한 것으로 판단된다.