• Journal of Biomedical Engineering Research
• /
• v.25 no.5
• /
• pp.361-367
• /
• 2004

The axial compressive strength, relative 3-D stability and osteoconductive shape design of an intervertebral fusion cage are important biomechanical factors for successful intervertebral fusion. Changes in the stress distribution of the vertebral end plate and in cage stability due to changes in the spike shape of a newly contrived box-shaped fusion cage are investigated. In this investigation, the initial contact of the cage's spikes with the end plate and the penetration of the cage's spikes into the end plate are considered. The finite element analysis is conducted to study the effects of the cage's spike height, tip width and angle on the stress distribution of the vertebral end plate, and the micromigration of the cage in the A-P direction. The stress distribution in the end plate is examined when a normal load of 1700N is applied to the vertebra after inserting 2 cages. The micromigration of the cage is examined when a pull out load of l00N is applied in the A-P direction. The analysis results reveal that the spike tip width significantly influences the stress concentration in the end plate, but the spike height and angle do not significantly influence the stress distribution in the end plate touching the cage's spikes. In addition, the analysis results show that the micromigration of the cage can be reduced by adjusting the spike angle and spike arrangement in the A-P direction. This study proposes the optimal shape of an intervertebral fusion cage, which promotes bone fusion, reduces the stress concentration in a vertebral end plate, and increases mechanical stability.

• Journal of Korean Society of Steel Construction
• /
• v.14 no.6
• /
• pp.711-720
• /
• 2002

A 3-D numerical model, which could demonstrate the static and dynamic responses of a curved bridge more precisely with the moving vehicles, was developed The dynamic response induced by the centrifugal rolling motion of vehicle was identified according to the variations of the partial grade and the curvature of the slab. Dynamic characteristics of the curved bridge with the moving vehicle were analyzed under the condition of support types and two different support systems. Parametric studies were conducted to compare the efficiency of load distribution in the curved bridge. In general, while the vehicle was crossing the curved bridge, negative reaction occurred in the inside of the girder. The final result showed that the support system located outside the girder was more advantageous than other systems, and the characteristics of load distributions differed from the others in the various conditions of support systems.

• Journal of Korean Society of Steel Construction
• /
• v.9 no.3 s.32
• /
• pp.431-440
• /
• 1997

The paper describes a theoretical model for the prediction of bridge temperatures from meteorological data measured at bridge site and local meteorological center together with existing finite element heat transfer theory and solar radiation transfer theory to determine the time dependent temperature distribution of bridge. In this analytical model, the most adequate equation for the calculation of solar radiation on the bridge surface, which is dominant in day time is described based on the results of several experimental studies for the solar energy. The validity of this model is tested against field data obtained from long term experimental program on Sadang Viaduct in Seoul. Also, this paper describes the linear correlation between design variables and meteorological data to establish analytical criteria for the prediction of the average temperature, which are responsible for the longitudinal deformation of the bridges and of the vertical differential temperature profiles. which are responsible for the bending deformations from the long term experimental results.

• Korean Journal of Human Ecology
• /
• v.15 no.3
• /
• pp.457-467
• /
• 2006

The following research compares two mostly-used apparel systems that are used in colleges of Korea, Gerber and PAD, by analyzing advantages and disadvantages of their Dart, Tuck and Pleats-related functions in pattern construction process. The results are the following: First, regarding transformation methods, Gerber system was able to use pivot method, while PAD system was able to use both pivot and slash method. As for movement, distribution, synthesis, folding, producing additional Dart function, the PAD system was not able to synthesize more than two Darts, and only showed differences for other functions. On the other hand, the diamond-shape Dart and diagonal Dart can be produced only in PAD system, while none of curvy shaped Dart can be produced in both systems. Second, as for pattern outer line connection capability, which is a Dart automatic transformation function, both systems showed unnatural shapes and need for correction. Third, when constructing according to the type of Tuck, we could distribute multiple Darts at a time with PAD system, while with Gerber system, distribution into multiple Darts at a time was impossible at all. Fourth, when constructing according to the contour of Pleats, Gerber system made it possible to make construction of multiple lines and box/inverted Pleats with just one order, but PAD system required repetitive tasks, which remains room for enhancement in regard to such inefficiency.

• Journal of KIISE:Software and Applications
• /
• v.34 no.10
• /
• pp.937-944
• /
• 2007

In this paper, we propose multiple human tracking with an moving stereo camera. The tracking process is based on mean shift algorithm which is using color information of the target. Color based tracking approach is invariant to translation and rotation of the target but, it has several problems. Because of mean shift uses color distribution, it is sensitive to color distribution of background and targets. In order to solve this problem, we combine color and depth information of target. Also, we build human body part model to handle occlusions and we have created adaptive box scale. As a result, the proposed method is simple and efficient to track multiple humans in real time.

• Journal of the Korean Society for Advanced Composite Structures
• /
• v.2 no.1
• /
• pp.15-22
• /
• 2011

Pultruded fiber reinforced polymeric plastic (PFRP) structural members may be one of attractive alternatives of the structural members in the civil engineering applications because of its many advantageous mechanical properties. However, they have relatively low modulus of elasticity and also cross-sections of structural shapes are composed of thin plate components such as flange and web. Therefore, structural stability is an important issue in the design of pultruded structural compression members. For the design of pultruded structural member under compression, buckling and post-buckling strengths of plate components may be taken into account. In the structural steel design following AISC/LRFD, in addition to the buckling strength, the nonuniform stress distribution in the section is incorporated with a form factor. In this paper, the form factor for the design of PFRP structural member under compression is investigated through the analytical study. Furthermore, the process for the determination of the form factor is suggested.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.13 no.5
• /
• pp.142-151
• /
• 2005

To predict the fatigue life of the Hub Bearing Unit(HBU), preload effect and initial axial clearance have to be considered. Various theory and equations for the HBU design used in the passenger car are well developed in many literatures. But most design hand book for bearings or bearing catalogues do not consider the initial axial clearance and preload effect. So there are limits and difficulties to use those data in actual bearing design. To consider the preload effect and initial axial clearance, complex elliptic integrals and nonlinear equations are involved. These equations are difficult to solve during the design process. In order to solve these problems effectively, a program is developed to solve these equations reliably and to help the designer in obtaining the performance data of the HBU such as load distribution, maximum contact stress and fatigue life. The preprocessor of the program helps users to prepare the input data through a dialog box and the post processor makes graphical presentation of the result. In this paper, theoretical and numerical background for the prediction of the fatigue life of the HBU is explained. A simple example is presented to show the usefulness of developed program.

• Aerospace Engineering and Technology
• /
• v.7 no.1
• /
• pp.68-75
• /
• 2008

Space radiation environments depend on satellite mission orbit, period, and date, and it can be predicted by simulation. Total Ionizing Dose(TID) can be predicted by Dose-depth Curve which only inform the dose level depending on the shielding thickness. So detail effective shielding analysis considering real structure is necessary to predict part level TID. For this purpose, program is developed to calculate shielding thickness distribution by structure modeling and ray trace from certain point in the structure. Finally TID at certain point in the 3-dimensional structure can be calculated by integration of shielding distribution result and dose-depth curve data. Using this program, TID is analyzed at part level certain point by modeling of equipment box structure in the satellite.

• Journal of the Korean Geotechnical Society
• /
• v.26 no.12
• /
• pp.51-60
• /
• 2010

Earth pressure due to gravity generally increases linearly with the depth, but the distribution of earth pressure due to surface load depends on the loading condition, the ground condition, and the boundary condition. In this study, the earth pressure on a rigid wall due to the vertical surface load was measured in experiments. Rigid wall was built in the model test box, and it was filled with homogeneous sandy ground (width 30 cm, height 88 cm, length 110 cm). Rigid wall was composed of 8 segments, which were tested on the two load cells. In the tests, we observed the distribution of the earth pressure on the rigid wall depending on the vertical surface load and it's location. According to the test results, the lateral earth pressure due to the vertical surface load showed its maximum value at a constant depth and decreased with the depth, to the negligible value at the critical depth. The critical depth and the depth at which lateral earth pressure reaches its maximum were not decided by the magnitude of the vertical surface load. They were dependant on the distance from the rigid wall.

• Journal of applied mathematics & informatics
• /
• v.25 no.1_2
• /
• pp.67-83
• /
• 2007

The characteristics of steady two-dimensional laminar boundary layer flow of a viscous and incompressible fluid past a moving wedge with suction or injection are theoretically investigated. The transformed boundary layer equations are solved numerically using an implicit finite-difference scheme known as the Keller-box method. The effects of Falkner-Skan power-law parameter (m), suction/injection parameter ($f_0$) and the ratio of free stream velocity to boundary velocity parameter (${\lambda}$) are discussed in detail. The numerical results for velocity distribution and skin friction coefficient are given for several values of these parameters. Comparisons with the existing results obtained by other researchers under certain conditions are made. The critical values of $f_0$, m and ${\lambda}$ are obtained numerically and their significance on the skin friction and velocity profiles is discussed. The numerical evidence would seem to indicate the onset of reverse flow as it has been found by Riley and Weidman in 1989 for the Falkner-Skan equation for flow past an impermeable stretching boundary.