• Journal of the Korean Geotechnical Society
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• v.20 no.1
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• pp.61-73
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• 2004

Rayleigh wave and Love wave are the major elastic waves belonging to the category of the surface wave. The fact that Love wave is not contaminated by P-wave makes Love wave superior to Rayleish wave and other body waves. Therefore, the information that Love wave carries is more distinct and clearer than the information of Rayleigh wave. In this study, for the purpose of employing Love wave in the SASW method, the dispersion characteristics of the Love wave were extensively investigated by the theoretical, numerical and experimental approaches. The 2-D and 3-D finite element analyses for the half space and two-layer systems were performed to determine the phase velocities from Love wave as well as from both the vertical and the horizontal components of Rayleigh wave. Also, the SASW measurements were performed at the geotechnical sites to verify the results obtained by the numerical analysis. The results of the numerical analysis and the field testing indicated that the dispersion characteristics of Love wave can be an extended information to make better evaluation of the subsurface stiffness structure by SASW method.

• Journal of Korean Philosophical Society
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• v.142
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• pp.165-192
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• 2017

The purpose of this thesis is to explain the difference between Heidegger's hermeneutical philosophy and Gadamer's philosophical hermeneutics. The difference is to say that Heidegger's philosophy begins with Aristotle's theory of category and transcendental philosophy. On the other hand, the beginning of Gadamer's philosophical research is Plato's dialog, philosophy and Hegels dialectic. 2. Heidegger regards humanism as a variant of the modern ideal of human beings. On the contrary, Gadamer understands humanism as a place where romantism leads to the ideals of human education. 3. Heidegger says that the hermeneutical circle is still a logical and existential structure of the circle. On the contrary, Gadamer understands the circle as a circle between the whole and the part. This circle is the law of traditional hermeneutics derived from the tradition of rhetoric. 4. Heidegger says Plato's philosophy is the first beginning of the substance metaphysic, Hegel's philosophy the end of the subject metaphysic. On the contrary, Gadamer says the hermeneutical understanding and the hermeneutical interpretation is endless. 5. Heidegger's ontology is as Sein zum Tode a future oriented and eschatological. On the contrary, Gadamer's hermeneutic is as Sein zum Text always the way to a past, the infinite openness.

• Journal of Ocean Engineering and Technology
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• v.10 no.3
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• pp.74-82
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• 1996

수면상에 떠있는 2차원 물체에 작용하는 시간평균 표류력 및 표류모오멘트를 비점성 선형 포텐셜 이론을 사용하여 계산하는 방법에 대하여 검토하였다. 부유체 접수면상의 압력을 직접적분하여 구한 수평방향 표류력이 특정주파수 부근에서 음의 값을 보이고 있다. 이는 무한원방에서의 에너지 보전방법에 의한 표류력이 항상 양의 값을 취한다는 기존 이론과 상이하다. 본 논문에서, 이러한 차이가 부유체의 횡요 및 상하동요에 기인한 복원력의 성분과 횡요와의 연성효과에 의하여 발생하였음을 규명하였다. 이는 횡요가 있는 경우, 표류력을 산출하는 기존의 무한원방 방법에 결함이 있음을 보이고 있다. 이에 반하여 기존의 접수면압력 직접적방법은 부유체에 작용하는 시간평균 표류력 및 표류모오멘트를 모든 주파수에 대하여 정확하게 산출한다고 결론지울 수 있다.

• Journal of KSNVE
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• v.9 no.3
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• pp.466-471
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• 1999

The prediction methods of diffraction field in barrier has beenreported much about the infinite length barrier and it is very few work that reasonable sound source was used in experiment. This study, however, has worked about the several model barrier with acoustic scale model experiment. In the case of scale model experiment, it is difficult to use the kind of source with sufficiently characteristics. A spark discharge sound source with the high repeatability, broad band spectra, small size and omnidirectivity has veen used for the prediction of diffraction field. Several model barriers with different length on the ground were considered for the experiment and compared with the the results calculated by the approximation.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.4
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• pp.203-210
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• 2020

Spatial variation of diffracting wave amplitudes along a semi-infinite breakwater is investigated using the analytical solution of Penney and Price (1952) for wave diffraction. On the front side of the breakwater, the fluctuation of wave amplitudes due to diffracting waves would cause a wave force greater than that of superposed incident and reflected waves. The diffracting wave phase varies in circular shape from the breakwater tip of (x, y) = (0, 0) whereas the incident and reflected wave phases vary in planar shape. So, the total wave amplitude of the incident (or reflected) waves and the diffracting waves would fluctuate at a position away from the energy discontinuity line. The position (x, y) = (0, y) on the front and lee sides of the breakwater is at a distance y(π/2 - β) of the point on the energy discontinuity line along the diffracting wave crest line. The degree of reduction of the diffraction wave energy is proportional to the distance from the point on the energy discontinuity line along the diffracting wave crest line. Therefore, the diffracting wave amplitudes on the front and lee sides of the breakwater would be inversely proportional to the square root of y(π/2 - β).

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.28 no.4
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• pp.240-249
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• 2016

In this study, we investigated wave force distribution at points on a vertical structure of semi-infinite breakwater considering diffraction. Wave forces of monochromatic and random waves on a vertical structure are studied considering diffractions in front and lee side of the breakwater for non-breaking wave condition. We selected width of breakwater are 0 for reference condition. In monochromatic wave case, relative wave force becomes 0 on the head of the breakwater by acting incident wave force and diffracting wave force simultaneously and oscillating patterns of relative wave force occurs based on 1.0 as distance from the head increases. Relative wave force of monochromatic waves decreases as incident wave angle increases. Relative wave force of random waves is defined by using ratio of root mean square and wave force spectrum in this study. The case considering random phase of each wave components are compared to the case which don't consider random phase and both results are almost similar. Relative wave force of random waves is also 0 near the head of the breakwater likewise monochromatic wave. Oscillating pattern of relative wave force of random waves becomes relatively weaker for composition of each wave components as distance from the head increases.

• Geophysics and Geophysical Exploration
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• v.11 no.2
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• pp.153-160
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• 2008

Seismic modeling is used to simulate wave propagation in the earth. Although the earth's subsurface is usually semi-infinite, we cannot handle the semi-infinite model in seismic modeling because of limited computational resources. For this reason, we usually assume a finite-sized model in seismic modeling. In that case, we need to eliminate the edge reflections arising from the artificial boundaries introducing a proper boundary condition. In this study, we changed three kinds of boundary conditions (sponge boundary condition, Clayton and Engquist's absorbing boundary condition, and Higdon's transparent boundary condition) so that they can be applied in elastic wave modeling for anisotropic media. We then apply them to several models whose Poisson's ratios are different. Clayton and Engquist's absorbing boundary condition is unstable in both isotropic and anisotropic media, when Poisson's ratio is large. This indicates that the absorbing boundary condition can be applied in anisotropic media restrictively. Although the sponge boundary condition yields good results for both isotropic and anisotropic media, it requires too much computational memory and time. On the other hand, Higdon's transparent boundary condition is not only inexpensive, but also reduce reflections over a wide range of incident angles. We think that Higdon's transparent boundary condition can be a method of choice for anisotropic media, where Poisson's ratio is large.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.06a
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• pp.297-302
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• 1999

Finite element analysis is peformed about the crack propagation in half-space due to sliding contact. The analysis is based on linear elastic fracture mechanics and stress intensity factor concept. The crack location is fixed and the friction coefficient between asperity and half-space is varied to analyze the effect of surface friction on stress Intensity factor for horizontal crack. The crack propagation direction is predicted based on the maximum range of shear and tensile stress intensity factor.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.06a
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• pp.30-37
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• 1999

헤르츠 접촉하에 있는 반무한체에서의 표면균열을 살펴보았다. 시편의 응력확대계수 K를 구하기 위해 사용되는 간단화된 방법을 이 논문에 쓰여진 모델에 적용시켰다. 기존에 알려진 결과에 비해 상당히 만족스런 결과를 얻었으며 다른 방법보다 이 방법이 훨씬 더 편리함이 입증되었다.

• Tribology and Lubricants
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• v.17 no.5
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• pp.373-379
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• 2001

The problem of interest is formulating elastic contact problem of a layered semi-infinite solid in terms of Fourier integral. The plane strain problem is considered for a solid composed of homogeneous isotropic two layers with different mechanical properties. General solutions for the subsurface stress and deformation field of frictionless elastic bodies under normal loading using of Fourier transformation technique are obtained. The numerical results for the stress distribution of coated solid for some particular cases are given.