• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.2
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• pp.234-242
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• 2002

A shape optimal design of synthetic intervertebral disc prosthesis is performed using a three-dimensional finite element method. Geometric parameters are introduced to model the cross-sectional geometry of the intervertebral disc. It is assumed that the total strain energy in the intact intervertebral disc is minimized under the normal load conditions, as often cited in other references. To calculate the stain energy density, both the nonlinear material properties and the large deformations are taken into account. The design variables of the annulus fiber angle and the area ratio of the nucleus pulposus are calculated as 31°and 30%, respectively, which complies well with the intact disc. Thus, the same optimization procedure is applied to the design of the synthetic intervertebral disc prosthesis whose material properties are different from the intact disc. For the given synthetic material properties, the values of 67°and 24% for the fiber angle and the area ratio are obtained.

• Steel and Composite Structures
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• v.19 no.4
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• pp.939-952
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• 2015

In this paper, brake pad performance of two organic matrix composites namely, Sample 1 (contains no brass filler) and Sample 2 (contains 1.5% brass filler), is studied based on tribological and squeal noise behavior. In the first stage, a pin-on-disc tribometer is used to evaluate the frictional behavior of the two pads. On the following stage, these pads are tested on squeal noise occurrence using a drag-type brake dynamometer. From the two type of tests, the results show that; (i) brass fillers play a dual role; firstly as reinforcing element of the brake pad providing primary contact sites, and secondly as solid lubricant by contributing to the formation of a layer of granular material providing velocity accommodation between the pad and the disc; (ii) brass fillers contribute to friction force stabilization and smooth sliding behavior; (iii) the presence of small weight quantity of brass filler strongly contributes to squeal occurrences; (iv) there is close correlation between pin-on-disc tribometer and brake dynamometer tests in terms of tribological aspect.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.23 no.3
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• pp.259-265
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• 2014

When the brakes of a vehicle are applied, large amounts of heat are generated on the surfaces of the brake discs owing to friction between the discs and the brake pads. A high temperature gradient on the disc surfaces leads to thermal deformation and severe disc abrasion. Ultimately, the thermal deformation and disc wear give rise to a thermal judder phenomenon, which has a major effect on the stability of the vehicle. To investigate and propose a solution to these problems, thermoelastic instabilities under applied thermal and mechanical loads were analyzed using the commercial finite element package ANSYS by considering the contact surfaces between the discs and pads. Direct-contact three-dimensional finite elements between the discs and pads were applied to investigate the disc friction temperature, thermal deformation, and contact stress so that the thermal judder phenomenon on the surface of the disc could be predicted.

• Geomechanics and Engineering
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• v.12 no.6
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• pp.919-933
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• 2017

A series of Brazilian tests under diameter compression for disc specimens was carried out to investigate the strength and failure behavior by using acoustic emission (AE) and photography monitoring technique. On the basis of experimental results, load-displacement curves, AE counts, real-time crack evolution process, failure modes and strength property of granite specimens containing two pre-existing holes were analyzed in detail. Two typical types of load-displacement curves are identified, i.e., sudden instability (type I) and progressive failure (type II). In accordance with the two types of load-displacement curves, the AE events also have different responses. The present experiments on disc specimens containing two pre-existing holes under Brazilian test reveal four distinct failure modes, including diametrical splitting failure mode (mode I), one crack coalescence failure mode (mode II), two crack coalescences failure mode (mode III) and no crack coalescence failure mode (mode IV). Compared with intact granite specimen, the disc specimen containing two holes fails with lower strength, which is closely related to the bridge angle. The failure strength of pre-holed specimen first decreases and then increases with the bridge angle. Finally, a preliminary interpretation was proposed to explain the strength evolution law of granite specimen containing two holes based on the microscopic observation of fracture plane.

• Steel and Composite Structures
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• v.20 no.6
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• pp.1205-1219
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• 2016

This paper presents a new type of pre-pressed spring self-centering energy dissipation (PS-SCED) bracing system that combines friction mechanisms between the inner and outer tube members to provide the energy dissipation with the pre-pressed combination disc springs installed on both ends of the brace to provide the self-centering capability. The mechanics and the equations governing the design and hysteretic responses of the bracing system are outlined, and a series of validation tests of components comprising the self-centering mechanism of combination disc springs, the friction energy dissipation mechanism, and a large scale PS-SCED bracing specimen were conducted due to the low cyclic reversed loadings. Experimental results demonstrate that the proposed bracing system performs as predicted by the equations governing its mechanical behaviors, which exhibits a stable and repeatable flag-shaped hysteretic response with excellent self-centering capability and appreciable energy dissipation, and large ultimate bearing and deformation capacities. Results also show that almost no residual deformation occurs when the friction force is less than the initial pre-pressed force of disc springs.

• Journal of Veterinary Clinics
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• v.28 no.1
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• pp.122-127
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• 2011

A 5-year old, intact male, Cocker spaniel dog was referred with paraplegia and loss of deep pain perception. Physical, neurological examinations, radiography, and computed tomography were evaluated. Based on the clinical examinations, the dog was diagnosed with severe disc herniation ($L_2$ to $L_3$ intervertebral disc space). On the next day of presentation (6 days after loss of deep pain perception), hemilaminectomy was performed. After decompression of spinal cord and removal of herniated disc materials, $1{\times}10^6$ canine allogenic adipose tissue-derived mesenchymal stem cells (MSCs) diluted by $50{\mu}l$ saline were directly applied to the injured site of the spinal cord. Ten weeks of follow-up after surgery, full recovery of deep pain perception and motor function were evaluated in both hind limbs. Based on the result, we suggest that the transplantation of allogenic adipose tissue-derived MSCs to dogs with spinal cord injuries could be a considerable method to expect better clinical outcomes in veterinary practice.

• 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 Academy of Nursing Administration
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• v.21 no.1
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• pp.43-52
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• 2015

Purpose: In this study, behavioral styles of Dominance, Influence, Steadiness, and Conscientiousness (DISC) were examined and differences in job satisfaction and clinical competence among newly hired nurses were explored. Methods: For this explanatory correlational research, 176 newly hired clinical nurses were recruited from three university hospitals and one general hospital located in Seoul and Gyeonggi province. Data were collected in August, 2013 though self-report questionnaires. Results: The distribution of behavioral styles was 11.4%, 42%, 29% and 17.6% for Dominance, Influence, Steadiness, and Conscientiousness respectively. DISC behavioral styles were associated with sub-areas of job satisfaction such as professional position and doctor-nurse relationship. DISC behavioral styles were significantly associated with the total score for clinical competence and sub-areas of data collection, basic nursing skills, critical thinking, education and leadership, and attitudes toward professional development and practical skills. Multiple linear regression analysis showed that DISC behavioral styles predicted clinical competence (Adj. $R^2$=.14, F=9.42, p<.001). Conclusion: A focus on cultivating influential and steady behavioral styles among newly hired nurses can be helpful in improving job satisfaction and clinical competence. There is a need to improve interpersonal relationships through a deeper understanding of each person's behavioral style based on the analysis of DISC behavioral styles.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.607-612
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• 2004

Disc brake noise continues to be a major concern throughout the automotive industry despite efforts to reduce its occurrence. Eliminating vibrations during braking is an important task for both vehicle passenger comfort and reducing the overall environmental noise levels. There are several classes of disc brake noise, the major ones being squeal, judder, groan, and moan. In this study, analytical model for moan noise of rear disk brake is investigated. Modeling of the disc brake assembly to take account of the effect of different geometrical and contact parameters is studied through the use of multi-body model. The contact stiffness of the caliper and torque member plays an important role in controlling brake vibration. Therefore, a suitable material pair at the caliper/body contact has been made. An ADAMS model of a rear disc brake system was integrated with a flexible suspension trailng arm from MSC/NASTRAN. A fully non-linear dynamic simulatin of brake system behavior, containing rigid and flexible bodies, was performed for a Prescribed set of operating conditions. Simulation results were validated using data from vehicle experimental testing.

• Transactions of the Society of Information Storage Systems
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• v.2 no.3
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• pp.178-183
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• 2006

A Blu-ray disc, which has a more than 25GB optical capacity, has been known as a promising next-generation optical disc format. It commonly has a 1.1 mm thick substrate and a 0.1 mm thick cover layer for beam transmitting and the protection of the reflecting surface. The cover layer is generally formed by the spin coating process. However, in conventional spin coating, small bumps are formed along the rim of the disc, which results in the fatal reading error. Numerical simulation of the thin film flow behaviors during spin coating with the commercial solver and optimal spinning conditions was obtained. Thickness distribution of the cover layer according to the variation of substrate's edge shape could be calculated as well. By modifying the shape of the substrate edge shape, the bumps along the disc rim could be minimized, and it was proved that the chamfered edge, around $5{\sim}10$ degree, is the simplest and most effective way to minimize the bumps.