• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.8 no.3
• /
• pp.85-90
• /
• 1988

A probabilistic model for the failure in a homogeneous soil slope is presented. The Safety of the slope is measured through its probability of failure rather than the customary factor of safety. The safety margin of slope failure is assumed to follow a normal distribution. Sources of uncertainties affecting characterization of soil property in a homogeneous soil layer include inherent spatial variability., estimation error from insufficient samples, and measurement errors. Uncertainties of the shear strength-along potential failure surface are expressed by one-dimensional random field models. The rupture surface, created at toe of a soil slope, has been considered to propagate towards the boundary along a path following an exponential (log-spiral) law. Having derived the statistical characteristics of the rupture surface and of the forces which act along it, the probability of failure of the slope was found. Finally the developed procedure has been applied in a case study to yield the reliability of a soil slope.

• Archives of design research
• /
• v.14 no.3
• /
• pp.211-220
• /
• 2001

The general characteristics of the elder gait are to show a tendency that stride length and cycle decrease compared with those of adult, then walk velocity decreases. Despite differences by age in design of elder footwear, the study on characteristics of elderly gait is few. This study aims to compare pressure distributions of elderly foot with those of young students by using EMED. The ground contact time on foot was longer than that of university students in Result. Elderly males and females have 1.12 times and 1.20 times greater maximum force over the whole areas on the foot during walking than that of younger males and females, respectively. The elderly have long ground contact time at the middle foot. The guidelines which should be considered in designing shoes for the elderly are proposed. The results can be applied to design of the elder footwear on the basis of ergonomics.

• Journal of the Korean Magnetics Society
• /
• v.2 no.1
• /
• pp.69-74
• /
• 1992

This paper describes the energy and speed characteristics of an induction coil-gun. The coil-gun has some merits that it can be easily installed and repeatedly used many times, it does not damage mechanically in the course of launch and the force exerted on the projectile is distributed uniformly. An equivalent circuit is employed for modeling the coil-gun. The circuit equations and equation of motion are then derived based on the equivalent circuit. These equations are solved numerically by using Runge-Kutta method. Finally the energy transfer ratios are obtained according to the variations of the resonant frequency of driving circuit and charging voltage of capacitors. The muzzle velocities of projectile are also obtained according to the variations of electrical conductivity and initial position of projectile, firing angle of driving circuit, charging voltage of capacitor and resistance of driving coil, respectively.

• Computational Structural Engineering
• /
• v.7 no.3
• /
• pp.105-113
• /
• 1994

Precast concrete(P.C.) large panel structures have usually weaker stiffness at joints than that of monolithic in-situ reinforced concrete structures. But structural designers do not in general take into account this characteristics of P.C. large panel structures and use the same analytical models as for the monolithic structure. Therefore, the results of analysis obtained by using these models may be quite different from those actually occurring in real P.C. structure. In this study, the change in force and stress distribution and deflections of structure caused by applying lower shear stiffness at vertical joints are investigated through trying several finite element modeling schemes specific for P.C. structures, Finally, for engineers in practice, a simplified model, which takes account of the effect of lower shear stiffness at vertical joints, is proposed with the understanding on possible amount of errors.

• Journal of the Korean Magnetics Society
• /
• v.8 no.5
• /
• pp.308-316
• /
• 1998

In this paper, the effects of lateral displacement on the thrust, lift force and (guide force) are investigated by 3-D Finite Element Analysis (FEA) in controlled-PM LSM which has some strong points that electrical power can be minimized and the thrust and lift force can be simultaneously obtained. The variations of airgap flux density and the forces concerning lateral displacement have been analyzed and the effect of lateral displacement and airgap length on the motor performance have been investigated in detail by analysis and experiment results. As the result of this study, the characteristics of PM-LSM concerning with the change of lateral placement and airgap have been made clear quantitatively.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2015.05a
• /
• pp.41-41
• /
• 2015

하천의 지형을 조사하고 계측하는 것은 하천을 연구하는 전문가들에게 필수적인 일이다. 하지만 하천의 지형을 계측하는 것은 쉽지 않으며, 조사를 하여도 유사의 이송으로 인하여 하천의 지형은 시간이 지남에 따라 변하게 된다. 그러므로 실험이나 모델링을 통하여 하천의 지형을 예측하고 모의하는 것은 중요한 연구이다. 모델링을 이용하여 유사이송에 의한 하상변동을 잘 예측하기 위해서는 하천의 복잡한 흐름을 정확히 모의하는 것이 중요하며 유사를 발생시키는 힘인 하상전단응력을 정확히 산정하는 것 또한 중요하다. 하상의 전단응력을 산정하는 방법으로는 대표적으로 로그법칙에 의한 방법, 레이놀즈응력 분포를 이용한 방법, 난류운동에너지를 이용한 방법 등이 있다. 앞서 말한 방법으로 산정된 전단응력 값은 차이를 보이며, 이는 하상변동을 정확히 모의하는 것에 문제를 발생시킬 수 있다. 따라서 본 연구에서는 곡선좌표계를 이용하여 3차원 유동 및 하상변동을 모의할 수 있는 수치모형을 이용하여 전단응력 산정 방법에 따른 하상변동량을 분석하는 것이다. 하천의 복잡한 흐름을 정확히 모의하기 위하여 본 연구에서는 RANS (Reynolds Averaged Navier-Stokes) 방정식을 3차원으로 해석하여 흐름 계산을 하였고 유사량 산정공식과 Exner 방정식을 이용하여 유사이송에 의한 하상변동을 계산하였다. 흐름 계산의 검증을 위하여 선행 연구의 실험을 대상으로 모의하였다. 그리고 곡선으로 된 실험 수로를 대상으로 전단응력 산

• Nuclear Engineering and Technology
• /
• v.7 no.2
• /
• pp.107-118
• /
• 1975

The lattice dynamics of Cr, Mo, and W are formulated in terms of a simple shell model in which the transition metal ions in the crystals are treated as deformable ions. The model involves a total of seven parameters; two charge parameters and five force constant parameters. The numerical values of the model parameters are determined by fitting to three elastic constants and the lattice vibrational frequencies measured by the neutron inelastic scattering experiments. Attempts are made to compute the phonon dispersion relations, the frequency distribution functions, and the lattice specific heats of three metals. The results are compared with experiments. It is found that the simple shell model can give a satisfactory account for the lattice vibrational characteristics of transition metals. The usefulness of the model is then discussed in comparison With other lattice dynamical models.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.20 no.3
• /
• pp.213-220
• /
• 2000

The method of photoelasticity allows one to obtain principal stress differences and principal stress directions in a photoelastic model. In the classical approach, the photoelastic parameters are measured manually point by point. The previous methods require much time and skill in the identification and measurement of photoelastic data. Fringe phase shifting method has been recently developed and widely used to measure and analyze fringe data in photo-mechanics. This paper presents the test results of photoelastic fringe phase shifting technique for the stress analysis of a circular disk under compression and an edge-cracked plate subjected to tensile load. The technique used here requires four phase stepped photoelastic images obtained from a circular polariscope by rotating the analyzer at $0^{\circ}$, $45^{\circ}$, $90^{\circ}$ and $135^{\circ}$. Experimental results are compared with those or FEM. Good agreement between the results can be observed. However, some error may be included if the technique is used to general direction which is not parallel to isoclinic fringe.

• Korean Journal of Remote Sensing
• /
• v.20 no.4
• /
• pp.245-252
• /
• 2004

The mechanism of cold core eddy formation was investigated using boundary conditions between the East China coastal cold water and the Kuroshio Warm Current, wind data related to the monsoon which was measured by QuikSCAT, and the bottom topography of the East China Sea. When winds blow from the southeast at an intensity comparable to that in the winter period in 1999 and 2003, the warm Kuroshio and Tsushima Current became stronger, and temperatures were considerably higher than those of the extended cold water of the coast of the East China. At that time, the cold water was captured by warm water from the Kuroshio and the Tsushima Current. This facilitated the formation of mesoscale cold core eddies with diameter of 150km in the East China Sea in May, 1999 and February, 2003. The cold core eddy which was detected by NOAA, SeaWiFS and QuikSCAT satellites. The East China Sea is considered to be important not only as a good fishing ground but also nursery and spawning area for many kinds of fishes. Therefore, it would be worth studying spatio-temporal variations of the cold core eddy in the environmental conditions of the northwestern East China Sea using systematic remote sensing techniques.

• The Journal of Korean Academy of Prosthodontics
• /
• v.46 no.1
• /
• pp.1-11
• /
• 2008

Statement of problem: Over the past decade, increased demand for esthetically pleasing restorations has led to the development of all-ceramic systems. Recent reports suggest that the all-ceramic crowns have excellent physical properties, wear resistance, and color stability. In addition, numerous ceramics have excellent biocompatibility, a natural appearance, and improved physical bonding with resin composite luting agents. However, the brittle nature of ceramics has been a major factor in their restriction for universal usage. Functional occlusal loading can generate stress in the luting agent, and the stress distribution may be affected by the marginal geometry at the finish line. Tooth preparation for fixed prosthodontics requires a decision regarding the marginal configuration. The design dictates the shape and bulk of the all ceramic crowns and influences the fit at the margin. Purpose: The purpose of this study was to evaluate the stress distribution within marginal configurations of all- ceramic crowns (90-degree shoulder, 110-degree shoulder, 135-degree shoulder). Material and methods: The force is applied from a direction of 45 degrees to the vertical tooth axis. Three-dimensional finite element analysis was selected to determine stress levels and distributions. Results and conclusion: The result of stress level for the shoulder marginal configuration was more effective on stress distribution at 135-degree shoulder margin. But the stresses concentrated around at 135-degree shoulder margin. The stress decreased apically at the surface between cements and alumina core, and increased apically at the surface between alumina core and veneering porcelain.