• Journal of Korean Ophthalmic Optics Society
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• v.11 no.4
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• pp.337-344
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• 2006

Purpose: To evaluate the vision-specific Quality of Life according to modes of refractive error correction in myopia. Method: This study included subjects from two different universities in Korea during March 2005 to June 2005. The following subjects (470) were university students, university faculty members, and their immediate families; all of whom were over the age of 19 and all who had refractive error of some sort. The four focus groups consisted of 171 spectacle wearers, 154 contact lens wearers, 123 refractive surgery patients, and 22 post-refractive surgery patients who returned to wearing glasses. The study of Vision-Specific Quality of Life used QIRC - The Quality of Life Impact of refractive Correction Questionnaire, which was translated by our group from English into Korean. Using analysis of co-variance (ANCOVA) and adjusting for age, sex, job, economic status, and education level, we examined and compared the QOL mean scores of the three groups (glass & contact lenses wears, refractive surgery patients, and post-refractive surgery patients who returned to wearing glasses). Results: After adjusting for major compounding variance, the research results showed the highest QOL mean score of 43.2 for the group who had received refractive surgery, 37.1 for the glasses & contact lenses group, and 33.4 for patients who had returned to wearing glasses after refractive surgery. There were significant differences between the three groups (p=0.001). Conclusion: Refractive surgery has shown a significant contribution to improve the QOL in myopia patients. However, upon our investigation, patients who underwent refractive surgery and returned to wearing glasses had a lower QOL compared to non-refractive surgery patients who wore glasses/contact lenses. Upon concluding our studies that shows that refractive surgery does not always conclusively bring higher QOL, we would like patients to carefully consider their options before undergoing refractive surgery in the future.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.6
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• pp.609-617
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• 2012

The impact, spreading and recoil processes of a nanoparticle-laden droplet impacting on a horizontal solid surface are numerically investigated by solving the conservation equations for mass, momentum, energy and mass fraction. The liquid-air interface is tracked using a level-set method that is modified to include the effect of contact angle hysteresis at the wall. The species transport equation including a thermal diffusion term is additionaly solved to determine the nanoparticle distribution in the droplet. The effect of nanoparticle concentration and contact angle are also studied.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1859-1863
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• 2007

A new type of a fretting wear tester has been designed and developed in order to simulate the actual vibration behavior of a nuclear fuel rod for springs/dimples in room temperature. When considering the actual contact condition between fuel rod and spring/dimple, if fretting wear progress due to the flow-induced vibration (FIV) under a specific normal load exerted on the fuel rod by the elastic deformation of the spring, the contacting force between the fuel rod and dimple that were located in the opposite side should be decreased. Consequently, the evaluation of developed spacer grids against fretting wear damage should be performed with the results of a cell unit experiments because the contacting force is one of the most important variables that influence to the fretting wear mechanism. Therefore, it is necessary to develop a new type of fretting test rig in order to simulate the actual contact condition. In this paper, the development procedure of a new fretting wear tester and its performance were discussed in detail.

• Proceedings of the KSME Conference
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• 2001.06b
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• pp.295-300
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• 2001

In recent years, as changing the habit of eating, the pathology in the colon grows up annually. For that reason, the colonoscopy is generalized. But it requires much time to acquire a dexterous skill to perform an operation. And the procedure is painful to the patient. Therefore, biomedical and robotic researchers are developing a locomotive colonoscope that can travel safely in colon. In this paper, we propose a novel design and concept of semi-autonomous colonoscope and two actuators for the micro robot. The micro robot comprises camera and LED for diagnosis, steering system to pass through the loop, pneumatic actuator and bow-shaped flexible supporters to control a contact force and to keep the space between colon wall and the actuator. For actuating mechanism, we suggest two models. One is based on the reaction force, and the other is impact force. In order to validate the concept and the performance of the actuators, we carried out the preliminary experiments in rigid pipes.

• Korean Journal of Culture and Social Issue
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• v.25 no.2
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• pp.119-135
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• 2019

There have been many efforts to reduce prejudice and discrimination against people with mental illness in our community. Studies have shown that the threat to people with mental illness is a important factor. In this study, we focused on contact experience and sense of community that are believed to influence both realistic and symbolic threat We looked the differences in threat depending on the type of contact(family, friends/coworker, public places, no contact) with people with mental illness. Next, if there is contact experience, we questioned that the quality of the experience could influence the threats in all types of contact. Finally, could contact experience and sense of community affect the threats? The total of 465 respondents were surveyed in this study. The result showed that the realistic threat were not different depending on the types of contact, but that the symbolic threat were more higher people with no-contact experience than people with contact experience. The quality of experience had a significant effect on both threats, except in the case of the family contact on realistic threat. Lastly, sense of community was analyzed as a significant variable for both realistic and symbolic threats. Based on these results, we discussed the impact of contact and sense of community and implications of this study.

• Composites Research
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• v.12 no.5
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• pp.54-64
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• 1999

This study investigated the impact behaviors of the stitched sandwich composites under the low energy impact by the use of drop weight impact tester. These sandwich composites condidted of the glass fabric faces with a urethane foam core. The upper face and the lower face were stitched to combinr through the core thickness direction using the polyester reinforcements. Four types of the stitched sandwich composites, each having a different core thickness, were tested to determine the effects of the core thickness. The impact conditions were changes with the variations of the mass and drop height of the impact tup. The test results showed that the core thickness and the impact condidtions such as the drop height and the mass of the impact tup affected the impact force, the contact time, and the strain behaviors of the stitched sandwich composites. The stitched sandwich composites are able to avert the damage and also maintain the structural integrity even thouth the presence of the damage owing to the through-the-thickness reinforcements. However, it is important to improve the wetting ability of the stitched reinforcements so that the conventional structures are substituted for the stitched sandwich composites effectively.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.04a
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• pp.504-512
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• 2003

Simulation programs have been developed and used as an attempt to improve the accuracy of Non-Destructive Evaluation(NDE) techniques. The applicability of these programs is very limited, however, because it is difficult to describe the delicacy of the propagation of stress waves. To investigate the applicability of the finite element analysis for stress wave-based NDE techniques numerical simulation for Impact-Echo method and SASW method is performed. The numerical studies are performed to determine the essential parameters such as contact time of impact load, mesh size and time step size. These studies show that the choice of parameter is very important for improving the accuracy and confidence of the numerical procedure and, thereby, the applicability of the numerical analysis for stress wave-based NDE techniques

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.04a
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• pp.42-48
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• 1997

The dynamic response of symmetric cross-ply and angle-ply composite laminated plates under impact loads is investigated using a higher order shear deformation theory. A modified Hertz law is used to predict the impact loads and a four node finite element is used to model the plate. By using a higher order shear deformation theory, the out-of-plane shear stresses, which can be a crucial factor in the failure of composite plates, are determined with significant accuracy. The results compared with previous investigations showed good agreement. The effect of ply sequence and ply angle on the contact force is also studied.

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.3
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• pp.532-537
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• 2011

This paper describes the development of SPH(Smooth Particle Hydrodynamics) scheme and integration into the multi-material shock physics code(ExLO) for the purpose of the application to the extreme large deformation problems. SPH numerical scheme has been extended into the fluid dynamics and the high-speed impact events, such as space structure protection against space debris and meteorite catering. Like other hydrocodes, SPH scheme also solves the conservation equations with the constitutive equation including equation of state. The benchmark problem, Taylor-Impact test, was simulated and the predictions show good agreements with both the published numerical data and experimental data. Currently, the contact treatment between materials is under development.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.3
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• pp.713-722
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• 1991

본 연구에서는 graphite/epoxy와 glass/epoxy 그리고 graphite/epoxy와 kevl- ar/epoxy의 혼합적층된 복합재료 평판의 저속충격에 대한 응답을 유한요소 모델을 사 용하여 수치해석 한후, 각각의 단일적층판들의 결과와 비교하였으며, 이때의 접촉력 관계식은 Yang과 Sun이 제안한 수정된 접촉법칙을 이용하였다. 또한, 수치해석 결과 에서의 충격자의 속도변화로써 혼합적창판 배열에 따른 에너지 흡수율을 계산하였고, 이를 충격특성이 취약한 graphite/epoxy 단일 적층판의 결과와 비교 고찰하였다.