• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.283-288
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• 2011

The high heat resistant material for brake disc is required for higher speed trains. Although Aluminum is very expensive, it which has high thermal conductivity and low density has been adapted to high performance light-weight brake disc. In this study, we carry out the thermal stress analysis for suggested shape of Al hybrid brake disc which was designed to meet the optimal point between a performance and economic side. And we compare the results from the analysis to results of conventional disc at the same braking speed. The result show that the temperature on braking surface of Al hybrid disc is lower than the temperature on conventional disc surface, whereas the maximum thermal stress is larger than stress on conventional disc.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 V
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• pp.2669-2672
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• 2003

This paper describes a new method of discrimination between the normal disc and the rewritable one. The conventional method of disc discrimination, using Focus error signal, has a heavy fluctuations. To achieve an accurate discrimination, in this paper, the sum of side beam［1］signal is used for that. A new approach is expected to improve the performance of disc discrimination as well as to reduce the signal variation almost by 50％. Techniques in this paper are applicable to the all types of optical disc player, such as CD (compact disc), VCD(Video-CD) and DVD (digital versatile disc) and any other optical disc players.

• The Journal of Korean Physical Therapy
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• 제15권2호
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• pp.52-66
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• 2003

The intervertebral disc is a cartilaginous structure that resembles articular cartilage in its biochemistry, but morphologically it is clearly different. It shows degenerative and ageing changes earlier than does any other connective tissue in the body, It is believed to be important clinically because there is an association of disc degeneration with back pain. Degenerative changes in the intervertebral disc are thought to develop as aging, mechanical stress and metabolic factors. Genetic factors may also play a part in the onset or progress of the degenerative process. They, together with environmental factors, may act as determinants of the structural characteristics of the intervertebral disc and produce a tendency to generation, In this short review we outline the morphplogy and biochemistry of normal intervertebral disc and the changes that arise during degeneration. Therefore this study will review degeneration of intervertebral disc, so we will have knowledge about low back pain associated with degenerative change in the intervertebral disc.

• 한국정밀공학회지
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• 제18권6호
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• pp.109-114
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• 2001

Forming pressure of the rupture disc has been analyzed theoretically and verified by experiments. Final shape of the rupture disc after forming process is assumed to be hemi-ellipsoid for small height of the rupture disc. The predicted forming pressures are in good agreement with those by experiment. A new simple model has been proposed to predict the burst pressure of the rupture disc. Experimental results show that the proposed model of burst pressure describes the bursting characteristics of the rupture disc very well.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 춘계학술대회 논문집
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• pp.798-803
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• 2007

The brake system of railway plays an important role to enhance the speed of train, and the brake disc is one of major components relating to frictional braking. The performance enhancement of brake disc directly affects the braking performance of train. It is required to understand and investigate the factors need to be considered for the development of new brake disc with improved materials and performance. In this study, through the literature reviews of previous study, several factors including thermal crack phenomena, friction coefficient, materials and durability of disc, temperature characteristics, etc., were introduced for the design of improved brake disc. Moreover, based on the review results, the design direction of new brake disc was suggested. Eventually, a new brake disc with improved performance would be developed based on this investigation.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.1056-1061
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• 2003

CD-R disc drive is one of the basic options of personal computer today. In this trend, various CD-R discs can be purchased in every market. Even very low quality discs are in market too. Today's CD-R disc drive is being operated over 10,000 RPM. So the possibility of the disc fracture is growing faster. Sometimes, during the test of a new disc drive by various methods to confirm the quality of it, fracture of the disc happens. And it happens in end user's personal computer scarcely. In this reason, new methods to confirm the quality and the failure mechanism of the optical disc are studied in this paper.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.150-155
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• 2004

The base material of optical disc is the amorphous polymer, polycarbonate. So crack growth on the rotating optical disc could happen by the static centrifugal force. This phenomenon is called static fatigue. Today's CD-R disc drive is being operated over 10,000 RPM. This is increasing the possibility of the disc fracture when operating. In this reason, new method to measure the static fatigue threshold quality and the way to calculate the threshold J-integral value and the safe crack length of the optical disc are studied. Finally the environmental effect to optical disc is also studied in this paper.

• 한국자동차공학회논문집
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• 제24권1호
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• pp.1-9
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• 2016

Optimum cross-sectional shape of an automotive disc brake was developed based on FEM thermal analyses and the Taguchi method. Frictional heat flux and convection heat transfer coefficients were first calculated using equations and applied to the disc to calculate accurate temperature distribution and thermal deformations under realistic braking conditions. Maximum stress was generated in an area with highest temperature under pads and near the hat of ventilated disc and vanes. The SN ratio from Taguchi method and MINITAB was applied to obtain the optimum cross-sectional design of a disc brake on the basis of thermal deformations. The optimum cross-section of a disc can reduce thermal deformation by 15.2 % compared to the initial design.

• 한국임상수의학회지
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• 제20권4호
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• pp.519-522
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• 2003

An appearance of herniated intervertebral disc into thoracolumbar vertebral canal was evaluated in two patients using computed tomography (CT). Before CT scanning, plain radiography and myelography were performed in both cases. CT images were compared to those of myelography. Dogs were positioned in sternal recumbency under inhalation anesthesia and transverse slices with 2 mm thickness were obtained around thoracolumbar region. The transverse CT images were examined using both vertebral and spiral window mode. The most common findings on CT images were loss of vertebral canal epidural fat, bulging of vertebral canal disc margins, displacement of spinal cord and flatted vertebral canal. Whereas, narrowed intervertebral disc space and simple extradural pattern were the main findings on plain and contrast radiographs. CT imges showed the extent of the herniated disc lesion, type II intervertebral disc hernation, and the displacement of spinal cord in detail in both occations. It is considered that degree and precise localization of the intervertebral disc herniation and subtle lesion of spinal cord could be identified accurately using computed tomography.

• Journal of Acupuncture Research
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• 제32권3호
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• pp.107-115
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• 2015

Objectives : The aim of this study is to investigate the state of cervical disc herniation according to the degree of cervical lordosis and age. Methods : 67 records of inpatients who were diagnosed with herniated intervertebral disc(HIVD) of the cervical spine were analyzed. Cobb's method, Jochumsen method and the Ishihara index were used to measure the degree of cervical lordosis. The state of the cervical disc was identified using magnetic resonance imaging(MRI) of the cervical spine. Then correlations among cervical lordosis, age and cervical disc herniation were analyzed. Results : Disc bulging was associated with hypolordosis and disc protrusion was associated with hyperlordosis and age. Disc extrusion was not associated with either cervical lordosis or age. The number of disc herniations in the cervical spine was correlated with age significantly, but not with cervical lordosis. Conclusions : Cervical disc herniation had a tendency to correlate with age and cervical lordosis, although this is not definite. Future studies that analyze more radiographic images of patients with HIVD of the cervical spine might be necessary to identify the influence of cervical lordosis on cervical disc herniation.