• 대한조선학회지
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• 제25권2호
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• pp.11-18
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• 1988

The radiation problem for an oscillating cylinder advancing under the free surface with a constant horizontal velocity is studied using the Green integral equation in the frequency domain. The Green function expressed in terms of the complex exponential, is derived using the damped free surface condition. Special attention is given to the behavior of the numerical solution in the vicinity of the critical Brard number ${\gamma}_c=\omega{\cdot}u/g=0.25$ where $\omega$ is the circular frequency of encounter, u the advancing speed and g the gravitational acceleration. It is shown that the solution is finite in the vicinity of ${\gamma}_c$ although the Green function becomes singular at ${\gamma}_c$. It is also shown that the computed hydrodynamic coefficients agree well with those obtained from the solution of the same problem formulated in the time domain.

• Structural Engineering and Mechanics
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• 제54권4호
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• pp.623-648
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• 2015

A numerical approach is presented for the analysis of the forced vibration of a rigid surface foundation with arbitrary shape. In the analysis, the foundation is discretized into a number of sub squaree-lements. The dynamic response within each sub-element is described by the Green's function, which is obtained by the Fourier-Bessel transform and Precise Integration Method (PIM). Incorporating the displacement boundary condition and force equilibrium of the foundation, it obtains a system of linear algebraic equation in terms of the contact forces within each sub-element. Solving the equation leads to the desired dynamic impedance functions of the foundation. Numerical results are obtained for foundation not only with simple geometrical configurations, such as rectangular and circular foundation, but also the case of irregularly shaped foundation. Several comparisons between the proposed approach and other methods are made. Very good agreement is reached. Also, parametric studies are carried out on the dynamic response of foundation. Addressed in this study are the effects of Poisson's ratio, material damping and contact condition of soil-foundation interface. Several conclusions are drawn the significance of the factors.

• ETRI Journal
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• 제44권3호
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• pp.512-523
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• 2022

Random delay countermeasures introduce random delays into the execution flow to break the synchronization and increase the complexity of the side channel attack. A novel method for attacking devices with random delay countermeasures has been proposed by using a maximal overlap discrete wavelet transform (MODWT)-based power trace alignment algorithm. Firstly, the random delay in the power traces is sensitized using MODWT to the captured power traces. Secondly, it is detected using the proposed random delay detection algorithm. Thirdly, random delays are removed by circular shifting in the wavelet domain, and finally, the power analysis attack is successfully mounted in the wavelet domain. Experimental validation of the proposed method with the National Institute of Standards and Technology certified Advanced Encryption Standard-128 cryptographic algorithm and the SAKURA-G platform showed a 7.5× reduction in measurements to disclosure and a 3.14× improvement in maximum correlation value when compared with similar works in the literature.

• Coupled systems mechanics
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• 제11권3호
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• pp.199-215
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• 2022

The present paper deals with the axisymmetric deformation in homogeneousisotropic thermoelastic solid with two temperatures, with and without energy dissipation using modified couple stresstheory. The effect of energy dissipation and two temperature isstudied due to the concentrated normalforce, normalforce overthe circularregion, thermal pointsource and thermalsource over the circular region. The Laplace and Hankel transform techniques have been used to find the solution to the problem. The displacement components, conductive temperature distribution, stress components and couple stress are computed in the transformed domain and further calculated in the physical domain using numerical inversion techniques. Effects of two temperature and energy dissipation on the conductive temperature,stress components and couple stress are depicted graphically.

• Coupled systems mechanics
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• 제12권3호
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• pp.261-276
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• 2023

This article is an application of new modified couple stress thermoelasticity without energy dissipation in association with two-temperature theory. The upper and lower surfaces of the plate are subjected to an axisymmetric heat supply. The solution is found by using Laplace and Hankel transform techniques. The analytical expressions of displacement components, conductive temperature, stress components and couple stress are computed in transformed domain. Numerical inversion technique has been applied to obtain the results in the physical domain. Numerically simulated results are depicted graphically. The effect of two temperature is shown on the various components.

• Coupled systems mechanics
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• 제13권3호
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• pp.231-245
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• 2024

In the present work, a microelogated thermoelastic model based on Lord-Shulman (1967) and Green-Lindsay (1972) theories of thermoelasticity has been constructed. The governing equations for the simulated model are converted into two-dimensional case and made dimensionless for further simplification. Laplace and Hankel transforms followed by eigen value approach has been employed to solve the problem. The use of eigen value approach hasthe advantage of finding the solution of governing equationsin matrix form notations. This approach is straight forward and convenient for numerical computation and avoids the complicate nature of the problem. The components of displacement,stress and temperature distribution are obtained in the transformed domain. Numerical inversion techniques have been used to invert the resulting quantities in the physical domain. Graphical representation of the resulting quantities for describing the effect of microelongation are presented. A special case is also deduced from the present investigation. The problem find application in many engineering problems like thick-walled pressure vesselsuch as a nuclear containment vessel, a cylindricalroller etc.

• 대한수학회지
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• 제49권1호
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• pp.69-83
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• 2012

In this note, we present certain circular domain, named Forelli-Rudin construction or Hua construction, which is built on Cartan domains. We compute the explicit Bergman kernel for it and get the corresponding weighted Bergman kernel on its base.

• 한국생물물리학회:학술대회논문집
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• 한국생물물리학회 1996년도 정기총회 및 학술발표회
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• pp.25-25
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• 1996

A mature mutant ribose binding protein (RBP) of Escherichia coli was obtained by site-directed mutagenesis, replacing Thr-3 in the N-domain of wild-type mature RBP (WT -mRBP) with a Trp residue (N- Trp-mRBP). The equilibrium unfolding properties and the refolding kinetics of this protein were monitored by fluorescence and circular dichroism (CD). (omitted)

• 한국해안·해양공학회논문집
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• 제23권5호
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• pp.335-344
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• 2011

곡면의 경계를 가지는 수로에서 비선형 파랑의 상호작용을 모의하기 위한 비정수압 자유수면 모형이 개발되었다. 제안된 모형은 비선형의 3차원 Navier-Stokes 방정식을 곡선좌표 영역에서 계산단계 분리법의 일종인 압력수정법에 의하여 수치적으로 해석된다. 특히, 연직방향으로 변형된 형태의 엇갈린 격자를 이용하여 상대적으로 간단하게 압력방정식과 자유수면 경계조건을 구성하였다. 개발된 모형의 수치해석 정확도는 2차원의 수치 파수조에서 파랑의 비선형 정도에 대하여 5차의 스토스우크스 해석해와 비교하였다. 본 모형의 실제적 적용은 원형의 수로에서 회절과 반사에 의해 변형되는 비선형 파의 변형에 초점을 맞추어 수행하였다. 두개의 파를 중첩한 고비선형의 파에 대한 경우를 제외하고 수치해석 결과는 비선형적인 영향을 고려하지 않은 해석해의 선형적인 중첩과 일치하였다. 두개의 파를 중첩한 고비선형의 파에 대한 모의를 통하여 본 모형은 원형의 수로에서 비선형 군파의 변형에관한 수치적인 모의 가능성을 제시하였다.

• Korea-Australia Rheology Journal
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• 제21권3호
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• pp.193-200
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• 2009

We present a direct simulation technique for two-dimensional mold-filling simulations of fluids filled with a large number of circular disk-like rigid particles. It is a direct simulation in that the hydrodynamic interaction between particles and fluid is fully considered. We employ a pseudo-concentration method for the evolution of the flow front and the DLM (distributed Lagrangian multipliers)-like fictitious domain method for the implicit treatment of the hydrodynamic interaction. Both methods allow the use of a fixed regular discretization during the entire computation. The discontinuous Galerkin method has been used to solve the concentration evolution equation and the rigid-ring description has been introduced for freely suspended particles. A buffer zone, the gate region of a finite area subject to the uniform velocity profile, has been introduced to put discrete particles into the computational domain avoiding any artificial discontinuity. From example problems of 450 particles, we investigated the particle motion and effects of particles on the flow for both Newtonian and shear-thinning fluid media. We report the prolonged particle movement toward the wall in case of a shear-thinning fluid, which has been interpreted with the shear rate distribution.