• Korean Journal of Metals and Materials
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• v.50 no.4
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• pp.316-323
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• 2012

The aim of this study is to investigate the effect of post heat treatment on bonding properties of roll cladded Ti/MS/Ti materials. First grade Ti sheets and SPCC mild steel sheets were prepared and then Ti/MS/Ti clad materials were fabricated by a cold rolling and post heat treatment process. Microstructure and point analysis of the Ti/MS interfaces were performed using the SEM and EDX Analyser. Diffusion bonding was observed at the interfaces of Ti/MS. The thickness of the diffusion layer increased with post heat treatment temperature and the diffusion layer was verified as having $({\epsilon}+{\zeta})+({\zeta}+{\beta}-Ti)$ intermetallic compounds at $700^{\circ}C$ and an $({\zeta}+{\beta}-Ti)$ intermetallic compound at $800^{\circ}C$, respectively. The micro Knoop hardness of mild steel decreased with post heat treatment temperature; however, those of Ti decreased at a range of $500{\sim}600^{\circ}C$ and showed a uniform value until $800^{\circ}C$ and then increased rapidly up to $900^{\circ}C$. The micro Knoop hardness value of the diffusion layer increased up to $700^{\circ}C$ and then saturated with post heat treatment. A T-type peel test was used to estimate the bonding forces of Ti/Mild steel interfaces. The bonding forces decreased up to $800^{\circ}C$ and then increased slightly with post heat treatment. The optimized temperature ranges for post heat treatment were $500{\sim}600^{\circ}C$ to obtain the proper formability for an additional plastic deformation process.

• Food Science of Animal Resources
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• v.36 no.1
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• pp.68-76
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• 2016

This study was conducted to investigate the meat quality and sensory properties of 12 major cuts from 10 Hanwoo bulls (25-32 mon of age) after they were aged at 2℃ for 0, 7, 14, and 21 d. Protein content (%) was between 19.17 and 22.50%. Intramuscular fat content ranged from 2.79 to 8.39%. The collagen content of the chuck roll, chuck tender, and short plate muscles was higher (1.97-2.04%) than that of the striploin muscles (1.48%) (p<0.05). CIE lightness (L*) values increased with an increase in aging days for tenderloin, loin, chuck roll, oyster blade, short plate, top sirloin, and eye of round muscles (p<0.05). Most muscles, except the short plate, showed no significant changes in redness CIE (a*) and yellowness (b*) color values during aging. The tenderloin, loin, and striploin showed significantly higher water holding capacity (58.60-62.06%) than that of chuck roll and short plate (53.86-57.07%) muscles (p<0.05). The Warner-Bratzler shear force values of most muscles decreased significantly as the aging period increased (p<0.05), exception the tenderloin. The chuck tender muscles showed the highest cooking loss, whereas tenderloin muscle showed the lowest (p<0.05). The tenderloin muscle had the longest sarcomere length (SL) (3.67-3.86 μm) and the bottom round muscle had the shortest SL (2.21-2.35 μm) (p<0.05). In the sensory evaluation, tenderness and overall-likeness scores of most muscles increased with increase in aging days. The tenderloin and oyster blade showed relatively higher tenderness and overall-likeness values than did the other muscles during the aging period. No significant differences were noted in juiciness and flavor-likeness scores among muscles and aging days.

• Journal of Ocean Engineering and Technology
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• v.28 no.5
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• pp.466-473
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• 2014

Underwater gliders do not have any external propulsion systems that can generate and control their motion. Generally, underwater gliders would obtain a propulsive force through the lift force generated on the body by a fluid. Underwater gliders should be equipped with mechanisms that can induce heave and pitch motions. In this study, an inner movable and rotatable mass mechanism was proposed to generate the pitch and roll motions of an underwater glider. In addition, a buoyancy control unit was presented to adjust the displacement of the underwater glider. The buoyancy control unit could generate the heave motion of the underwater glider. In order to analyze the underwater dynamic behavior of this system, nonlinear 6-DOF dynamic equations that included mathematical models of the inner movable mass and buoyancy control unit were derived. Only kinematic characteristics such as the location of the inner movable mass and the piston position of the buoyancy control unit were considered because the velocities of these systems are very slow. The effectiveness of the proposed dynamic modeling was verified through sawtooth and spiraling motion simulations.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.5
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• pp.1887-1895
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• 2013

In this study, physical experiments were performed in a two-dimensional wave flume to investigate the hydraulic and structural performance of a SFT model. The experiments were made by generating regular waves of different heights and periods under various conditions of buoyancy to weight ratio (BWR) and water depth as well. Through the analysis of the experimental data, it was clarified that the sway and heave motions of the tunnel body linearly increased with wave height and period. In contrast, the roll motion was rather insignificant unless wave height and period were comparatively large as the design wave. Similarly proportional relationship with respect to wave height and period was obtained in case of the maximum tensile force acting on the tension legs and the wave loads on the tunnel body. Regarding the change of water depth or BWR conditions, generally decreasing trend was obtained according to increase of water depth but decrease of BWR for both of the magnitudes of structural behaviors or wave loadings on the SFT structure.

• Korean Journal of Applied Biomechanics
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• v.21 no.2
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• pp.223-230
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• 2011

The purpose of this study was to analysis the effect of form and hardness of outsoles on the motion of the lower extremity joints and on foot pressure during gait. The subjects were 15 women(mean age, $48.5{\pm}2.4$ years), who had no serious musculoskeletal, coordination, balance or joint/ligament problems within 1 year prior to the study. The pelvic tilt, joint angles at the lower extremities and the vertical ground reaction force(GRF) were compared during gait with 3 types of shoes (A, B, C) by using one-way repeated ANOVA(p<.05). During gait, the peak tilt angle and the range of motion(ROM) of the ankle and knee joints were found to be significantly different among the 3 types of shoes. The type C shoes showed a significantly lower mean second maximum vertical GRF than types A and B. The curved outsoles of type C shoes, which had a form and hardness different from those of A and B, was designed strategically for walking shoes to provide stability to the Additionally, type C induced the dispersion of eccentric pressure and made the center of pressure roll over to the center line of the foot.

• Physical Therapy Korea
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• v.9 no.3
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• pp.113-124
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• 2002

The objectives of this study was to investiage the effects of sitting posture on carpal tunnel syndrome. Carpal tunnel syndrome (CTS) continues to be one of the most widely publicized maladies of the cumulative trauma disorder. Many studies have reported a positive association between CTS and highly repetitive work, high force, and poor posture. High force and repetitive work have especially been associated with CTS, but the evidence for work being a primary cause of CTS is strongest when these factors are combined. In addition to carpal tunnel syndrome, hand, wrist, and other disorders are attributed to these work-related movements. Such disorders are referred to as repetitive stress injuries, cumulative trauma disorder, overuse syndromes, and chronic upper limb pain syndrome. Incorrect posture also may play a role in the development of CTS in people who work at a computer and other types of keyboards. The tendency to roll the shoulders forward, round the lower back, and thrust the chin forward can shorten the neck and shoulder muscles, compressing nerves in the neck. This, in turn, can affect the wrist, fingers, and hand. The treatment and prevention of carpal tunnel syndrome continue to be approached with a segmental view of the human body. For example, the most common ergonomic solution for carpal tunnel syndrome associated with keyboard use is to keep the wrists in a neutral position by using a wrist rest in front of the keyboard and good sitting posture.

• The Journal of the Acoustical Society of Korea
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• v.11 no.4
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• pp.5-13
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• 1992

The vibration of a vehicle, which is caused by and transmitted from the engine, has significant effect on the ride comfort and the dynamic characteristics of the engine mount system has direct influence on the vibration and noise of the vehicle. This paper examines the body shake caused by the engine excitation force on engine key-off of a jeep by experiment and computer simulation using a general purpose mechanical system program, DADS. The computer simulation model consists of the engine, body including frame, and front and rear axles and each axle has right and left tires. The force element between body and suspension is modeled as a combination of suspension spring and damper, and the unsprung mass has roll and pitch motion. The body shake obtained from experiment was compared with the result of computer simulation. Parametric study of the body shake on engine key-off is performed with changing the stiffness of engine mount rubber, the engine mount installation angle and position of engine mounts by using the verified computer simulation model.

• Journal of the Korean Magnetics Society
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• v.5 no.1
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• pp.1-7
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• 1995

${(Fe_{0.85}Co_{0.15})}_{75}Al_{7}B_{18-x}Nb_{x}(x=2,\;4\;and\;6\;at%)\;and\;{(Fe_{0.85}Co_{0.15})}_{75}Al_{y}B_{21-y}Nb_{4}(y=3,\;5,\;7,\;9\;at%)$ alloys were prepared by a single-roll quenching method. Microstructure and magnetic properties of the alloys such as saturation magnetization, initial permeability, coercive force and power loss have been investigated as functions of composition and armea1ing temperature. Nanocrystallines are obtained by armealing of as-prepared amorphous alloys in all compositions except the alloy of 9 at% AI. Saturation magnetization increases after armea1ing and, decreases with Nb content. However, AI and B affects the saturation magnetization insignificantly. Initial perrreability of nanocrystallized alloy at 50 kHz is improved roore than twice compared to that of the as-prepared alloy. Coercive force and core loss reach less than half after armea1ing.

• Journal of the Microelectronics and Packaging Society
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• v.27 no.2
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• pp.19-26
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• 2020

Flexible displays have been evolved into curved, foldable, and rollable as the degree of bending increases. Due to the presence of brittle electrodes (e.g. indium-tin oxide (ITO)) that easily cracked and delaminated under severe bending deformation, lowering mechanical stress of the electrodes has been critical issue. Because of this, mechanical stress of brittle electrode in flexible displays has been analyzed mostly in terms of bending radius. On the other hand, in order to make rollable display, various mechanical components such as roller and spring are needed to roll-up or extend the screen for the rollable display apparatus. By these mechanical components, brittle electrode in the rollable display is subjected to the excessive tensile stress due to the retracting force as well as the bending stress by the roller. In this study, mechanical deformation of rollable OLED display was modeled considering boundary conditions of the apparatus. An analytical modeling based on the classical beam theory was introduced in order to investigate the mechanical behavior of the rollable display. In addition, finite element analysis (FEA) was used to analyze the effect of mechanical components in the apparatus on the brittle electrode. Furthermore, a strategy for improving the mechanical reliability of the rollable display was suggested through controlling the stiffness of adhesives in the display panel.

• Structural Engineering and Mechanics
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• v.48 no.4
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• pp.479-500
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• 2013

This paper presents the experimental as well as analytical study conducted on layer-bonded scrap tire rubber pad (STRP) isolators to develop low-cost seismic isolators applicable to structures in developing countries. The STRP specimen samples were produced by stacking the STRP layers one on top of another with the application of adhesive. In unbonded application, the STRP bearings were placed between the substructure and superstructure without fastening between the contact surfaces which allows roll-off of the contact supports. The vertical compression and horizontal shear tests were conducted with varying axial loads. These results were used to compute the different mechanical properties of the STRP isolators including vertical stiffness, horizontal effective stiffness, average horizontal stiffness and effective damping ratios. The load-displacement relationships of STRP isolators obtained by experimental and finite element analysis results were found to be in close agreement. The tested STRP samples show energy dissipation capacity considerably greater than the natural rubber bearings. The layer-bonded STRP isolators serve positive incremental force resisting capacity up to the shear strain level of 150%.