• Steel and Composite Structures
• /
• 제19권6호
• /
• pp.1421-1447
• /
• 2015

In this paper, the effect of material-temperature dependent on the wave propagation of a cantilever beam composed of functionally graded material (FGM) under the effect of an impact force is investigated. The beam is excited by a transverse triangular force impulse modulated by a harmonic motion. Material properties of the beam are temperature-dependent and change in the thickness direction. The Kelvin-Voigt model for the material of the beam is used. The considered problem is investigated within the Euler-Bernoulli beam theory by using energy based finite element method. The system of equations of motion is derived by using Lagrange's equations. The obtained system of linear differential equations is reduced to a linear algebraic equation system and solved in the time domain and frequency domain by using Newmark average acceleration method. In order to establish the accuracy of the present formulation and results, the comparison study is performed with the published results available in the literature. Good agreement is observed. In the study, the effects of material distributions and temperature rising on the wave propagation of the FGM beam are investigated in detail.

• Advances in nano research
• /
• 제7권2호
• /
• pp.135-143
• /
• 2019

The important effect of porosity on the mechanical behaviors of a continua makes it necessary to account for such an effect while analyzing a structure. motivated by this fact, a new two-step porosity dependent homogenization scheme is presented in this article to investigate the wave propagation responses of functionally graded (FG) porous nanobeams. In the introduced homogenization method, which is a modified form of the power-law model, the effects of porosity distributions are considered. Based on Hamilton's principle, the Navier equations are developed using the Euler-Bernoulli beam model. Thereafter, the constitutive equations are obtained employing the nonlocal elasticity theory of Eringen. Next, the governing equations are solved in order to reach the wave frequency. Once the validity of presented methodology is proved, a set of parametric studies are adapted to put emphasis on the role of each variant on the wave dispersion behaviors of porous FG nanobeams.

• 수산해양교육연구
• /
• 제25권1호
• /
• pp.1-11
• /
• 2013

The aim of this study was estimated the characteristics of the wave propagation by the water level conditions using a numerical modeling method at the Wando sea area. For three cases numerical simulation on the condition of incident and incoming of the deepwater design wave and the season normal wave, the spatial distribution of the incident wave at study area were investigated. And the calculated numerical modeling results were compared with measured field wave data. According to on-site wave data measured for 18 days, the range of the significant wave height and period were 0.10~1.14 m, 4.35~8.74 sec, respectively, and the maximum wave height were 0.15~1.66 m. From the results of numerical model for offshore design wave incident, the wave height attacked from Southern-East direction at this study area were over maximum 10.5 m because of rapidly change of water depth. Numerical modeling by three water level conditions of Approxmate Lowest Low Water Level(Approx. L.L.W), Mean Sea Level(M.S.L) and Approximate Highest High Water Level(Approx. H.H.W) were practiced. From the results for the case of Approx. H.W.L, variations of wave height at the back area of islands were about 1.6 m at maximum value for the case of deepwater design wave incoming. The significant wave heights of winter season were bigger than summer under normal wave condition, the incident wave height over 5.5 m decreased by shielding effect of islands. The change of maximum wave height at summer season were distinct than winter and was about 1.2 m and 0.8 m, respectively.

• Applied Microscopy
• /
• 제42권3호
• /
• pp.136-141
• /
• 2012

Diversification and individualization are pursued to fulfill the increasing human desire for beauty. There are many methods to change human appearances; of these, a permanent wave is often applied to improve beauty. A permanent wave uses physical and chemical methods to break and reform the bonds of natural hair. Thus, research into the optimized conditions for permanent waves is necessary to minimize hair damage and improve the efficiency of the treatment. The object of this study is to examine the effect of varying the alkalinity (8%, 12%, and 16%) of the permanent wave treatment on the wave efficiency, degree of hair damage via tensile strength, and degree of hair protein release. The results indicate that the treatment with the highest alkalinity (16%) is more effective than that with 8% alkalinity; however, the degree of hair damage when treated with the 16% alkalinity wave is higher than with the 8% alkalinity wave. Additionally, hair proteins increasingly dissolve with increasing alkalinity of the permanent wave.

• Ocean Systems Engineering
• /
• 제1권4호
• /
• pp.337-353
• /
• 2011

In the present study, an offshore platform having large partial porous cylindrical members, which are composed of permeable and impermeable cylinders, is suggested. In order to calculate the wave force on large partial porous cylindrical members, the fluid domain is divided into three regions: a single exterior region, N inner regions and N beneath regions, and the scattering wave in each fluid region is expressed by an Eigen-function expansion method. Applying Darcy's law to the porous boundary condition, the effect of porosity is simplified. Wave excitation forces and wave run up on the structures are presented for various wave conditions. For the idealized three-dimensional platform having large partial porous cylindrical members, the dynamic response evaluations of the platform due to wave forces are carried out through the modal analysis. In order to examine the effects of soil-structure interaction, the substructure method is also applied. The displacement and bending stress at the selective nodal points of the structure are computed using various input parameters, such as the shear-wave velocity of soil, the wave height and the wave period. Applying the Monte Carlo Simulation (MCS) method, the reliability evaluations at critical structure members, which contained uncertainties caused by dynamic forces and structural properties, are examined by the reliability index with the results obtained from MCS.

• 한국가시화정보학회지
• /
• 제16권3호
• /
• pp.8-15
• /
• 2018

Recently, as the high speed railway becomes more common, new environmental problems such as noise around tunnels are appearing. When a high speed train enters a tunnel, a compression wave in the tunnel is generated and propagated toward the tunnel exit at a sonic speed. When it reaches the tunnel exit, a part of compression wave radiates as a pulse typed impulse wave to the outside of tunnel. The impulse wave has an explosive noise. When the impulse wave is propagated around a village, it induces a serious noise or other problems to the resident. In order to solve these engineering problems, it is important to investigate the radiation characteristics of the impulse wave radiated from the tunnel exit. In this study, the effect of the length and angle of the baffle plate at the tunnel exit on the impulse wave radiated from the tunnel exit was investigated by numerical analysis. As a results, the baffle plate greatly affected the propagation of impulse wave.

• 한국해양학회지
• /
• 제19권2호
• /
• pp.195-199
• /
• 1984

풍파발생초기 세계에서 바람에 의해 형성된 취송류가 초기 단계의 파의 특성을 결정하는데 미치는 영향을 이론적으로 다루었다. 본 연구의 관점은 Phillips(1957)의 풍파발생이론의 관점과 유사하다. 취송류를 고려하면 Phillips가 구한 결과를 상당히 변경시키는 것으로 판명되었다. 특히 공명 조건에 있어서 취송류가 큰 역할을 하고 있다.

• 전자공학회논문지B
• /
• 제28B권5호
• /
• pp.335-342
• /
• 1991

A real-tme nonlinear parameter tomography is pumping wave method. This tomorgraphy has a merit which requires no 180$^{\circ}$ projection datum, while the ray-bending effect is remrkably remained on the reconstructed image. In this paper we intend to compensate this ray-bending effect using the perturbation method. Impulsive pumping wave makes derived compensative term simple form, nad the compensative image is easily obtained. We perform computer simulation to confirm the improvement of corrected imate.

• 한국윤활학회:학술대회논문집
• /
• 한국윤활학회 1999년도 제29회 춘계학술대회
• /
• pp.156-161
• /
• 1999

new bearing concept, the wave journal bearing, has been developed to improve the static and dynamic performances of an air-lubricated hydrodynamic journal bearing. This concept features waves on bearing surface. In this study, we present the solution of the compressible Reynolds equation valid for arbitrary Knudsen numbers. Straight wave journal bearing is investigated numerically. The performances of straight wave bearing are compared to the plain journal bearing over relatively wide range of bearing number and eccentricity. The wave journal bearing offers better stability than the plain journal bearing under a13 bearing numbers covered in this study. The bearing load and stability characteristics are dependent on the geometric parameters such as the amplitude and the starting point of the wave relative to the applied load. Under the condition of Knudsen number)0.01, we can not ignore the effect of slip for journal bearing.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
• /
• pp.316-318
• /
• 2004

In this study, the influence of electromagnetic wave effected on human body of light sensing was classified. Subjects of the eye was stimulated by the rays of LED and the measured electrical signals(EEG, EOG and ERG) in human body were compared and analyzed in the case of exposed at electromagnetic wave or not. The result show that when the subjects were not exposed at electromagnetic wave, the ratio of a wave has a large percentage in the EEG signal and the ratio of $\beta$ wave has come to good.