• Journal of Korean Ophthalmic Optics Society
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• v.16 no.1
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• pp.51-60
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• 2011

Purpose: This study was to investigate visual performance and subjective satisfaction with multifocal soft contact lenses at near works in university students. Methods: In a cross-over study design, 26 students (6 male, 20 female) who did not have any ocular disorder with at least 20/20(1.0) binocular vision were fitted with singlevision lenses (SofLens$^{TM}59$, Bausch + Lomb Co. USA) or multifocal lenses (SofLens Multifocal, Bausch + Lomb Co. USA). After 2 weeks, visual performance assessments included visual acuity, stereoacuity and contrast sensitivity function at distance and near. Near point of accommodation, accommodative facility, near point of convergence, vergence facility and near range of clear vision at near were examined. Students' satisfaction and preference were measured using survey questionaries. Results: Subjects maintained at least 20/20 binocular vision with multifocal and single-vision lenses at distance and near. There was no difference between multifocal and single-vision lenses in stereoacuity, contrast sensitivity function and vergence facility at far and near. The near point of accommodation, accommodative facility, near point of convergence and the near range of clear vision with multifocal lenses were better than single-vision lenses. On the survey questionaries, subjects reported that they preferred and satisfied with multifocal lenses with near works, and single-vision lenses with distance works. Conclusions: The majority of university students preferred multifocal to single vision lenses because multifocal lenses provided better visual performance at near works. This study suggests that multifocal lens is helpful for young adult in prolonged near works.

• Journal of Technologic Dentistry
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• v.29 no.2
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• pp.173-180
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• 2007

There was a great problem about the deposition between materials of a different kind at the beginnings of the introduction of porcelains, however, thereafter the deposition efficiency was settlded to the sufficient level of all user thanks to effort to have studied by many scholars and clinical authorities. But in a clinical process, as the difference of designs has an effect on fractures of porcelains, this researcher divided them into 4 groups of A: 1 mm, B: 2 mm, C: 3 mm, and D: 4 mm, and made 40 pieces to each 10 as the test samples to consider a length axis of tooth for studies in accordance with a position of a finishing line to meet between porcelain and metal at the contact point at the adjacent side to a metal porcelain. The sample materials are those to be use at the open market and the test samples wer completed by the same manufacturing technique to that of existent metal porcelain tube. s a result of the strength test on fractures, the average value is as in the following, A: 1 mm - 8.5bar, B: 2 mm - 10.5bar, C: 3 mm - 14.3bar, and D: 4 mm - 15.0bar. In case of the metal porcelain tube, the more faraway to process parts of metal and porcelain from the contact point of adjacent side has the stronger strength of fractures, Accordingly, the research shows that it had better to keep off more than 3 to consider a ledngth axis of tooth.

• Journal of the Korean Society of Safety
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• v.28 no.1
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• pp.88-94
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• 2013

The purpose of this study is to find out the difference of foot pressure according to the firefighter's work postures for providing the basic information to prevent Musculoskeletal disorders. This study was conducted by 9 male firefighters. Work postures were selected for rescuee handling, fire hose and hydraulic rescue equipment work postures. These were divided into 3 position, "High", "Middle" and the postures of taking out and letting down hydraulic rescue equipment were analyzed as starting point and end point respectively. Foot Pressure was used to analyze contact area, peak pressure, and maximum force in terms of work postures, and compared between fire hose and hydraulic rescue equipment work postures. The results of foot pressure are as follows. According to the results of rescuee handling work postures, one person handling posture showed wide contact area and foot pressure showed the highest at right foot. Accoridng to the (High), (Middle), (Low) postures of fire hose, the results didn't show the difference among the contact area, peak pressure and maximum force. As the results of hydraulic rescue equipment work postures, (Low) postures showed the highest in terms of the right foot of contact area, peak pressure and maximum force and (High) postures showed the highest in left foot. The increase of foot pressure lead to be inconvenience of low extremity and muscle fatigue for maintaining postural control cause pain. Thus, it is necessary to design insole-equipped working shoe for reduce the impulse and effect of foot during the rescuee handling work which standing out as foot pressure.

• Journal of the Microelectronics and Packaging Society
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• v.19 no.1
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• pp.55-60
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• 2012

In order to develop electroless-plated Nickel Phosphate (Ni-P) as a contact material for high efficient low-cost silicon solar cells, we evaluated the effect of ambient thermal annealing on the degradation behavior of interfacial adhesion energy between electroless-plated Ni-P and silicon solar cell wafers by applying 4-point bending test method. Measured interfacial adhesion energies decreased from 14.83 to 10.83 J/$m^2$ after annealing at 300 and $600^{\circ}C$, respectively. The X-ray photoelectron spectroscopy analysis suggested that the bonding interface was degraded by environmental residual oxygen, in which the oxidation inhibit the stable formation of Ni silicide phase between electroless-plated Ni-P and silicon interface.

• Journal of Oral Medicine and Pain
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• v.32 no.1
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• pp.105-111
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• 2007

Correlation between occlusal contact pattern and TMD have been hypothesized and partially investigated but results are controversial and not conclusive. The purposes of this study were to compare right-to-left difference of occlusal contact pattern, through contact points, contact force and occlusal balance, in the patients with unilateral TMD and also to evaluate its change related with TMD treatment. 36 patients with unilateral TMD from Department of Oral Medicine in Dankook University Dental Hospital were selected in this study (M:F=7:29, mean age of $29.2{\pm}14.8$ years). A computerized T-Scan II system (Tekscan, INC., USA) was employed for occlusal analysis and the simultaneity and occlusal balance through the number of tooth contact and magnitude of contact force were determined before and after TMD treatment. The number of contact points and contact force was more on the unaffected side than the affected side before treatment (p=0.056 and p=0.060, respectively) while significant difference between both sides was not found after treatment. The number of contact points and contact force on the affected sides significantly increased after treatment (p=0.038 and p=0.052), but the unaffected sides exhibited no significant difference between before and after treatment. In addition, sides difference in relative contact force decreased from about 27% to about 12% after TMD treatment (p=0.001). According to the results of this study, it is likely that unilateral TMD impairs right-to-left occlusal balance and that conservative TMD treatment alleviates the imbalance, subsequently leading to more symmetrical occlusal condition with increased contact points and force.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.10
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• pp.889-895
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• 2014

Machine parts and structures of a change in the displacement and strain can be evaluated safety is one of the important factors. Typically the strain gauge has been employed to measure the displacement and strain. However, this contact-type measurement method has disadvantages that are not measured under condition of specific object shape, surface roughness and temperature. In particularly, 3 point bending and 4 point bending test not use strain gauge. So its test used cross head displacement and deflect meter. Digital Image Correlation measurement methods have many advantages. It is non contact-type measurement method to measure the object displacements and strain. In addition, it is possible to measure the Map of full field displacements and strain. In this paper, measured the 3 point bending deflection using the Digital Image Correlation methods. In order to secure the reliability, Digital Image Correlation method and universal test machine were compared.

• Journal of Wetlands Research
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• v.12 no.2
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• pp.67-73
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• 2010

This study was performed to figure out what would be effective to maintain good water quality in the retention pond which was badly polluted before. In order to keep the good water quality of the retention pond it is necessary to prevent outer non-point source pollutants from flowing into the pond. In this study, we proposed to use porous slag as a blockage of the inflow into the pond from external non-point sources. We experimented with porous slag nets to see how the water is effected. With the results of the experiments, we found out there is a close correlation($r^2=0.9765$) between contact time and the removal rate of phosphorus, therefore we can conclude that contact time affects removal rate greatly. Synthetic wastewater, activated sludge effluent, and sewage were passed through a porous slag packed bed, both phosphorus and the suspended solid in water were removed highly. With the results of these tests, we proposed to set up a porous slag packed bed inside of the retention pond and revetment to prevent external non-point source pollutants flowing into the retention pond.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.366-369
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• 2003

The vertical fountain plating system with the point contact has been used in semiconductor industry. But the plating shape in the opening of photoresist becomes gradated shape, because bubbles from the wafer surface are difficult to escape from the deep openings, vias. So, we designed the tilted electrode ring contact to get uniform bump height on all over the wafer and evaluated the film uniformity by SEM and $\alpha$-step. A photoresist was coated to a thickness of $60{\mu}m$ and vias were patterned by a contact aligner After via opening, solder layer was electroplated using the fountain plating system and the tilted electrode ring contact system. In $\alpha$-step measurement, film uniformities in the fountain plating system and the tilted electrode ring contact system were ${\pm}16%,\;{\pm}3.7%$ respectively. In this study, we could get high uniformity bumps by the tilted electrode ring contact system. So, tilted electrode ring contact system is expected to improve workability and yield in module process.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.457-467
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• 2004

Wave Transmission analysis is one of methods for power transmission and reflection coefficients in coupled infinite structures. This paper focuses the wave transmission analysis of point coupled structures among semi-infinite beams and infinite thin plates considering all kinds of waves. It is supposed that the junction through the beams and plates is an identical spot and no point of contact exist except the spot. The boundary conditions are applied at the spot for continuities of 6 DOF displacements and 6 DOF force equilibriums, and then wave fields are obtained in the coupled structures. Since wave components in plate field are simplified using asymptotic expressions of Henkel functions, the displacements and forces at the plate junction can be simply expressed with magnitudes of the wave components. The wave fields according to incident waves gives the power transmission coefficients in beam/plate point coupled structures. For both coupled structures with a beam vertically and obliquely joined to a plate, power transmission analysis is performed and the analysis results are compared and examined.

• Korean Journal of Applied Biomechanics
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• v.16 no.1
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• pp.89-99
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• 2006

The study were to assess technical factors between the high score group and the low score group, from the subjects of 16 male national gymnasts, and to analyze the kinematical characteristic and main technical cause on technique of Akopian's 3D motion analysis of the male vaulting game in 2001 classification championship. The result of this study is this. There were not so much difference between the two groups in term; of the time of board contact, pre-flight, and total performance, but it takes shorter time when the players who are in the high point group take down the board, and they take long time for post-flight(p<.01). The high point group has a longer perpendicular distance in the moment of horse taking off, 0.05m on the average, than the low point group. The high point group shows 0.16m higher on the average than the other group in term; of the height of post-flight(p<.01). In the phase of board contact, the range of horizontal velocity at board take on were $7.66m/s{\sim}7.33m/s$, but there weren't significantly statistic differences between two groups. The hight score group were 0.68m/s faster than the low point group at the horizontal velocity at board take off event(<.05). About the average horizontal velocity of deceleration, AG1(-1.95m/s) reduces the speed more than AG2(-1.57m/s)(p<.05). And the hight score group were 0.37m/s faster than the low point group at the vertical velocity at horse take off event(<.05). When board taking off, the projectile angle of com were $38.7{\sim}37.8degree$ on the average. the comparative groups show almost same results. When horse taking off, the HPVy of the high point group were 37.6 degree which were a little higher than the low point group. The angular velocities of the players who takes on the horse with a right hand and then takes off with a left hand in the high point group were 14.97rad/sec, 10.82rad/sec in the low point group. However, the angular velocity of the players who takes on the horse with a left hand and then takes off on a right hand with the high point group were 14.97rad/sec, 15.56rad/sec in the low point group.