• Journal of Korean Physical Therapy Science
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• v.28 no.3
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• pp.42-52
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• 2021

Background: The purpose of this study was to investigate the effects of the severity and direction of lumbar disc herniation (LDH) on the facet joints and paraspinal muscles. Design: Cross-sectional design. Methods: The subjects were divided according to the diagnosis for severity of unilateral herniation of L4-L5 disc. The groups consisted of disc protrusion group (n=15), disc extrusion group (n=15), and no disc herniation group (n=15). The asymmetry and angle of facet joints and the cross-sectional area of paraspinal muscles were analyzed and compared using magnetic resonance imaging (MRI). Results: The results showed that the angle of facet tropism was larger in disc extrusion group than the disc protrusion group and the difference was found to be significant difference (p<0.01). In addition, when both left and right angles of patients with unilateral disc herniation were measured, the results showed larger facet joint angle in the herniated area of the disc extrusion group than in the disc protrusion group. When paraspinal muscles were measured according to the severity of disc herniation and the degree of facet joint asymmetry, there was no difference in paraspinal muscles between the disc protrusion and disc extrusion groups. Meanwhile, the multifidus muscle was smaller in the group with facet tropism than the group without facet tropism (p<0.03), while there were no significant differences in the erector spinae and psoas muscles. Conclusion: Progression of disc herniation resulted in increased facet joint tropism, increased angle of the facet joints in the direction of disc herniation, and decreased size of the multifidus muscle.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.396-401
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• 2008

The disc-pad brake system is an important part of automobile safety system. During braking, the kinetic energy and potential energies of a moving vehicle are converted into the thermal energy through frictional heat between the brake disc and the pads. Most of the thermal energy dissipated through the brake disc. The temperature could be exceed the critical value for a given material, which leads to undesirable effects, such as the brake fade, premature wear, brake fluid vaporization, bearing failure, thermal cracks, and thermallyexcited vibration. The object of the present study is to investigate temperature field and temperature variation of brake disc and pad during single brake. The brake disc is decelerated at the initial speed with constant acceleration, until the disc comes to stop. The pad-disc brake assembly is built by 3D model with the appropriate boundary condition. In the simulation process, the mechanical loads are applied to the thermomechanical coupling analysis in order to simulate the process of heat produced by friction.

• The Journal of Churna Manual Medicine for Spine and Nerves
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• v.14 no.1
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• pp.93-98
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• 2019

Objectives : This study aimed to introduce a new traction therapy and proposes that a new Chuna manual therapy technique could be implemented. Methods : The patient is placed in the prone position and their ankle is fixed to the fixing table. Next, clinicians contact on the vertebral spinal process above herniated disc region with the tissue pulled head part of scaphoid bone and the lower part of the pelvis is pulled horizontally to the foot. Conclusions : It was recently identified that traction while maintaining lumbar lordosis is more effective for lumbar disc herniation and is associated with fewer side effects. Chuna manual therapy also uses a technique of lumbar flexion-distraction manipulation to treat HIVD. further research is required.

• Tribology and Lubricants
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• v.25 no.6
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• pp.421-426
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• 2009

The brake system is important part of automobile safety system. The disc brake system is divided two parts: the rotating axisymmetrical disc and the stationary pads. During braking, the kinetic energy and potential energy of moving vehicle were converted into the thermal energy through frictional heat between the brake disc and the pads. The frictional heat, which is generated on the interface of the disc and pads, can cause high temperature during the braking process. The object of present work is to determine temperature and thermal stress, to compare to simulation results and experimental results in the disc by partial 3D model of ventilated disc brake with appropriate boundary conditions. In the simulation process, the mechanical loads were applied to the thermo-mechanical coupling analysis in order to simulate the process of heat produced by friction.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.6
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• pp.60-68
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• 2013

The present research aims to develop aluminum disc brakes to replace existing cast iron disc brakes in automobiles. The foundation for developing an aluminum disc is laid by investigating the performance characteristics of existing cast iron disc brakes and comparing those characteristics with those of aluminum disc brakes. This study involves FEM thermal/structural analysis of disc materials and experimental tests using a brake dynamometer. The results of this study show that, aluminum discs have not only better thermal/mechanical properties than existing cast iron discs, including better heat, wear, and crack resistance, but also that aluminum discs. Weigh less than existing cast iron discs, which results in improved maneuverability. Aluminum discs will become a more essential part of automobiles as electric cars become the major means of transportation.

• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.1
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• pp.57-78
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• 2022

The disc cutter and cutterbit, which are the most important factors to increase the excavation efficiency of TBM, are key factors in the design and construction of the cutter head. The arrangement, spacing, number, size, and material of disc cutters suitable for the ground conditions determine the success or failure of TBM construction. The disc cutter, which is a representative consumable part in TBM construction, can cause enormous disruption to the construction cost as well as the construction cost unless accurate prediction of wear and replacement cycle is accompanied. Therefore, in this study, the method of calculating the replacement cycle of the disc cutter calculated at the time of design for the slurry shield TBM field, and the depth of wear and replacement location of the disc cutter that occurred during actual construction were compared by analyzing the field data. For a quantitative comparison, weathered soil/weathered rock, soft rock, and hard rock were classified according to the ground in the section showing constant excavation data, and the trajectory of circle was different depending on the location of the disc cutter, so it was compared and analyzed.

• Transactions of the Society of Information Storage Systems
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• v.1 no.1
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• pp.42-47
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• 2005

We developed an optical pickup system which is used fer Blu-ray Disc. A liquid crystal element was used to make compensation for spherical aberration. Spherical aberration is a difficult problem in the optical pickup system for Blu-ray Disc. To reduce the effects of wavelength variation from the laser source, we designed a diffraction optical element. We took a measurement of all of the parts used to make a pickup system and validated the performance of each part. Then, we made a performance test fur the optical pickup system which we developed for Blu-ray Disc and the results were satisfactory.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.7
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• pp.22-28
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• 2019

In this study, as part of the subway braking system, the structural analysis was performed with the fatigue analysis by comparing subway brake disc and wheel-type brake. When structural analysis was performed, it was possible to verify that the wheel-type brake were higher than the brake discs in case of total deformation. As the same loading conditions were given to the subway brake disc and wheel-type brake, wheel-type brakes was shown to have more deformation than brake disk but lower damage than the subway brake disc. Comparing with each fatigue loading condition, the maximum fatigue life for 'Sample history' is found to be about 60 times longer than for 'SAE bracket history'.

• Tribology and Lubricants
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• v.26 no.1
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• pp.31-36
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• 2010

The brake system is an important part of the automobile safety system. The disc brake system is divided into two parts: a rotating axi-symmetrical disc, and the stationary pads. The frictional heat, which is generated on the interface of the disc and pads, can cause high temperatures during the braking process. The frictional heat source (the pads) is moving on the disc and the location is time-dependent. Our study applies a moving heat source, which is defined by the time and space variable on the frictional surface, in order to simulate the frictional heat behavior accurately during the braking process. The object of the present work is the determination of the temperature distribution and thermal stress in the solid disc by non-axisymmetric 3D modeling for repeated braking.

• Journal of Korean Neurosurgical Society
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• v.53 no.1
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• pp.31-38
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• 2013

Objective : Asymptomatic patients show high degeneration prevalence at lumbar disc in previous literatures. Unfortunately, there are few Korean data, so the authors attempted to analyze the prevalence of disc degeneration in highly selective asymptomatic Korean subjects using MRI. Methods : We performed 3 T MRI sagittal scans from T12 to S1 on 102 asymptomatic subjects (50 men and 52 women) who visited our hospital between the ages of 14 and 82 years (mean age 46.3 years). All images were read independently by three observers (two neurosurgeons and one neuroradiologist) who were not given any information about the subjects. We classified grading for lumbar disc herniation (HN), annular fissure (AF), and nucleus degeneration (ND), using disc degeneration classification. Results : The prevalence of HN, AF, and ND were 81.4%, 76.1%, and 75.8% respectively. Almost all levels showed an age-related proportional tendency with some exceptions. Conclusion : In asymptomatic Korean subjects, the abnormal findings showed high prevalence of AF, ND, and extrusion. Especially in young ages, the authors found that bulging, protrusion, and AF showed high prevalence at L4/5 and L5/S1. And ND showed high prevalence at L5/S1. So, all lumbar disc degenerations are not pathologic, especially in children and adolescents.