• Journal of the Korean Arthroscopy Society
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• v.13 no.3
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• pp.189-192
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• 2009

Although the articular cartilage is only a few milimiters thick, it has surprising stiffness to compression, exceptional ability to distribute load minimizing peak stress on subchondral bone and great durability. In many instances, it help to preserve normal joint function for more than 80 years. Varying in thickness, cell density, matrix composition, mechanical properties even within the same joint, it provides low-friction and pain free-motion. However, it lacks a blood or lymphatic supply and neurological elements are absent. It shows limited healing potential because of poor regenerative capacity.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1999.10a
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• pp.343-350
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• 1999

The purpose of this study is to compare the response of the high-strength concrete beam-column-slab subassembly with the response of a normal-strength concrete specimens. Four assemblies were designed 2/3 scale beam-column-slab joint(fc'=240kg/cm2 fc'=700kg/cm2) and tested to investigate seismic behaviour. From the test results 1) flexral cracks emerge to inside of bean deeply for high strength concrete member 2) the high-strength specimens represented stable hysteretic behaviour for the displacement ductility 5.5 but degradation in stiffness and strength and unstable hysteretic behaviors were observed owing to the brittleness of high-strength concrete beyond its range.

• Advances in aircraft and spacecraft science
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• v.3 no.4
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• pp.427-445
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• 2016

Star sensors are the attitude estimation sensors of the satellite orbiting in its path. It gives information to the control station on the earth about where the satellite is heading towards. It captures the images of a predetermined reference star. By comparing this image with that of the one captured from the earth, exact position of the satellite is determined. In the process of imaging, stray lights are eliminated from reaching the optic lens by the mechanical enclosures of the star sensors called Baffles. Research in space domain in the last few years is mainly focused on increased payload capacity and reduction in launch cost. In this paper, a star sensor baffle made of Aluminium is considered for the study. In order to minimize the component weight, material wastage and to improve the structural performance, an alternate material to Aluminium is investigated. Carbon Fiber Reinforced Polymer is found to be a better substitute in this regard. Design optimisation studies are carried out by adopting suitable design modifications like implementing an additional L-shaped flange, Upward flange projections, downward flange projections etc. A better configuration of the baffle, satisfying the design requirements and achieving manufacturing feasibility is attained. Geometrical modeling of the baffle is done by using UNIGRAPHICS-Nx7.5(R). Structural behavior of the baffle is analysed by FE analysis such as normal mode analysis, linear static analysis, and linear buckling analysis using MSC/PATRAN(R), MSC-NASTRAN(R) as the solver to validate the stiffness, strength and stability requirements respectively. Effect of the layup sequence and the fiber orientation angle of the composite layup on the stiffness are also studied.

• Tunnel and Underground Space
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• v.26 no.2
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• pp.68-86
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• 2016

Understanding the frictional properties of rock discontinuities is crucial to ensure the stability of underground structures. In particular, the frictional behavior at depth depends on the complex interaction among mechanical, hydraulic, thermal and chemical characteristics and their coupled effects. In this study, a series of shear tests were carried out in a triaxial compression chamber to investigate the shearing behavior of saw-cut granite surface and rough shear surface of synthetic rocks. The test results were analyzed using Coulomb's shear strength criterion. The frictional behavior of saw-cut granite surface showed little variation at different confining, water pressures and temperature conditions, however in case of synthetic rocks, the frictional behavior showed different trend depending on normal stress level. In addition, the variation of stiffness and dilation at different testing conditions were analyzed, and the stiffness and dilation showed little variation at different water pressures and temperature conditions.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.5
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• pp.584-590
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• 2012

The structural and functional disorder of a detrusor induces a bladder hypertrophy and degenerates a bladder muscle gradually by preventing normal urination. Thus, the thickness of the bladder wall has been increased in proportion to the degree of bladder outlet obstruction. In this study, the mechanical characteristics of the detrusor is analyzed for the physical properties and the thickness changes of the bladder muscle using a mathematically analytic method. In order to obtain the mechanical property of the bladder muscle, the tensile test of porcine bladder tissue is performed because its property is similar to that of human. The result of tensile test is applied to the mathematically model as Mooney Rivlin coefficients which represent the hyperelastic material. The model of the bladder is defined as the spherical shape with the initial volume of 50ml. The principal stress and strain according to the thickness are analyzed. Also, computer simulations for three types of the material property for the model of the bladder are performed based on the fact that the stiffness of the bladder is weakened as the progress of the benign prostatic hyperplasia. As a result, the principal stress is 341kPa at the initial thickness of 2.2mm, and is 249kPa at 6.5mm. As the bladder wall thickness increases, the principal stress decreases. The principal stress and strain decrease as the stiffness of the bladder decreases under the same thinkness.

• The Journal of Engineering Geology
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• v.12 no.3
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• pp.345-360
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• 2002

This study was for analysing the sedimentary rock slope stability and providing the reinforcement method that can heighten stability. The study area consists of Cretaceous basalt or basaltic tuff belonging to Hak-Bong Basalt Formation in Ha-Yang Group. Nature of geological structure confirmed in this area ars bedding, joint and fault. Majority of geological structure that affect most relationship rock slope stability is bedding. It is shown that dip direction is 120~160/15~25. In other structure, joint sets are shown that dip direction of set 1 is 310~330/65~85 and set 2 is 230~250/70~85. Joint set 3 shows above 85$^{\circ}$ high angle on NE trend although do not show clear. Stability analysis about rock slope used kinematic analysis, limit equilibrium method and FLAC by numerical analysis method. FLAC is continuum model that use Fintie Defferentce Method, but could use Interfaces Module and get discrete model's analysis effect such as UDEC.

• Structural Engineering and Mechanics
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• v.61 no.4
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• pp.497-510
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• 2017

A framed structure may be composed of two sub-structures, which are linked by a hinged joint. One sub-structure is the primary system and the other is the secondary system. The primary system, which is subjected to the periodic external load, can give rise to an auto-parametric resonance of the second system. Considering the geometric-stiffness effect produced by the axially internal force, the element equation of motion is derived by the extended Hamilton's principle. The element equations are then assembled into the global non-homogeneous Mathieu-Hill equations. The Newmark's method is introduced to solve the time-history responses of the non-homogeneous Mathieu-Hill equations. The energy-growth exponent/coefficient (EGE/EGC) and a finite-time Lyapunov exponent (FLE) are proposed for determining the auto-parametric instability boundaries of the structural system. The auto-parametric instabilities are numerically analyzed for the two frames. The influence of relative stiffness between the primary and secondary systems on the auto-parametric instability boundaries is investigated. A phenomenon of the "auto-parametric internal resonance" (the auto-parametric resonance of the second system induced by a normal resonance of the primary system) is predicted through the two numerical examples. The risk of auto-parametric internal resonance is emphasized. An auto-parametric resonance experiment of a ${\Gamma}$-shaped frame is conducted for verifying the theoretical predictions and present calculation method.

• The Journal of Pediatrics of Korean Medicine
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• v.24 no.1
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• pp.57-64
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• 2010

Objectives This study is to examine case that has an significant result on treating Polyarticular Type Juvenile Idiopathic Arthritis(JIA) the patient who did not response to DMARDs and NSAIDs with oriental medicine. JIA is the most common form of persistent arthritis in children before age 16. The symptoms of JIA is pain and edema of joints, fever, lethargy, reduced physical activity, and poor appetite. But the symptoms vary. Methods The patient felt pain and had limitation of mobility on his joints, but the DMARDs and NSAIDs were not effective. Therefore, he was treated with oriental medicine and withdrew from DMARDs and NSAIDs. The patient took DMARDs and NSAIDs from May 2007 to November 2008(He did not took DMARDs and NSAIDs from December 2007 to June 2008), and took oriental medicine from November 2008 until now. Results The patient's pain and limited mobility on his joints, edema, morning stiffness, fatigue was gone, and could maintain the condition. He doesn't have DMARDs or any other western medicine anymore. Conclusions This study shows that a Polyarticular Type Juvenile Idiopathic Arthritis patient who had ineffective response to DMARDs and NSAIDs can reach to the clinical remission by oriental medicine treatment. His morning stiffness, fatigue, pain of joints, edema was gone and ESR was in normal range with Oriental medicine treatment.

• Journal of the Korea Concrete Institute
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• v.22 no.1
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• pp.77-84
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• 2010

Latex modified concrete (LMC) exhibits improved material properties including high tensile strength and durability compared with conventional concrete, and hence LMC has been used as protective layers over the bridge deck slabs to increase their service life with underlying assumption of excellent bond behavior between the LMC overlay and the concrete substrate. In this study, the effect of the primary parameters of the concrete substrate (i.e., shrinkage, stiffness and cracking capacity) as well as the LMC overlay thickness on the probability of cracking of the bridge deck slabs using LMC overlays was investigated by carrying out the finite element analysis that simulated the bond behavior of LMC overlays on normal strength concrete (NSC) and HPC bridge deck slabs. Based on the results of the numerical analysis, it is concluded that the relatively high shrinkage strains and stiffness of HPC slabs can increase its probability of cracking in bridge deck slabs using LMC overlay.

• Magazine of the Korea Concrete Institute
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• v.10 no.4
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• pp.93-100
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• 1998

This paper presents a study on the flexural stiffness, plastic hinge length and plastic hinge rotation capacity of reinforced high performance concrete beams. 15 beams with different strength of concrete, reinforcement ratio and the pattern of loadings were tested. From the test results of reinforced normal strength concrete beams and reinforced high performance concrete beams with the concrete which has cylinder compressive strength of 700kg/${cm}^2$, slump value of 20~25cm and slump-flow value of 60~70cm. It is found that an extreme fiber concrete compressive strain of ${\varepsilon}_{cu}=0.0047$ may be used in ultimate curvature computations of reinforced high performance concrete beams. An empirical equation is proposed to estimate the effective moment of inertia. length and rotation capacity of plastic hinge of simply supported reinforced high performance concrete beams. The estimated deflections using this equation agree well with the experimental values.