• Journal of the Korean Society of Safety
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• v.33 no.4
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• pp.84-89
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• 2018

The number of landslides has increased since the 2000s due to the increased frequency of heavy rainfall caused by abnormal weather. A variety of debris flow prevention facilities have been installed as a countermeasure against this problem. However, it is not easy to evaluate the efficiency of debris flow prevention structures except for the structures with constant volume such as the erosion dam, because the other structures are limited to be reproduced in simulation program for debris flow. Therefore, the methods by which the debris flow prevention structures were modeled were proposed, and the efficiency of four prevention structures installed in Baekyang Mt. in Busan was evaluated with UDS, which accuracy had been verified, using these methods. The initial amount of debris flow was determined based on landslide which occurred in 2014, and specifications of the complex retaining walls around the settlements were measured and applied modeling for terrain. The numerical results showed that the efficiency of debris flow prevention structures could be quantitatively presented. Among the debris flow prevention structures installed in Baekyang Mt., prevention structure of barrier type for debris flow was the most efficiency and debris flow prevention device was the lowest efficiency when the only depth of debris was evaluated. It seems that this study is meaningful to propose the methods which were used to model the debris flow prevention structures that could not be reproduced in most 2D debris flow numerical analysis programs. If precise verification of the presented methods is carried out, it will be possible to provide clear criteria for the efficiency evaluation method of disaster prevention structures.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.7
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• pp.629-636
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• 2009

Mechanical stimulation is known to play a vital role on the differentiation of mesenchymal stem cells (MSCs) to pre-osteoblasts. In this research, we developed a tensile cell stimulator, composed of a DC motor-driven actuator and LVDT sensor for measuring linear displacement, to study the effects of tensile stress on osteogenic differentiation of MSCs. First, we demonstrated the reliability of this device by showing the uniform strain field in the silicon substrate. Secondly, we investigated the effects of tensile stretching on osteogenic differentiation. We imposed a pre-set cyclic strain at a fixed frequency on cell monolayer cultured on a flexible silicon substrate while varying its amplitude and duration. 60 min of resting period was allowed between 30 min of cyclic stretching and this cycle is repeated up to 7 days. Under the combined stimulation with osteogenic media and mechanical stretching, the osteogenic markers such as alkaline phosphatase (ALP), osterix, and osteopontin began to get expressed as early as 4 days of stimulation, which is much shorter than what is typically required for osteogenic media induced differentiation. Moreover, different markers were induced at different magnitudes of the applied strains. Lastly, for the case of ALP, we observed the antagonistic effects of osteogenic media when combined with mechanical stretching.

• Child Health Nursing Research
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• v.6 no.3
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• pp.316-328
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• 2000

This study aims at not only suggesting some ideas useful in planning and doing the sexual education in the primary schools in the near future putting into test the sexual education program which has been developed by researchers in accordance with the national education courses but also improve sexual health of the children through taking right sexual knowledge and sound sexual attitude. For this study 21 students are selected from all class of the fourth grade of the 'D' primary school at H district in KangWon-Do and have been taught the sexual education program during 6weeks, 12times. The findings of the study are as follows: 1. After the sexual education program, the sexual knowledge of the primary school children show to be significantly different from that they had before(t=-6.661, p=.000). So, this finding indicating that the sexual education program helps the children have and expand the correct sexual knowledge accordingly. 2. In order to look into any change of the sexaul attitudes of the primary school children after the sexual education program, there were significant difference(t=-3.808, p=.001). It is discovered that children come to have more affirmative and sound sexual attitude after sexual education program. As the findings of the study indicate, it may be concluded as follows: Since the sexual education program can affirmative influence on the sexual knowledge and sexual attitudes of the children, it is recommendable to start the sexual education program as early as possible in their childhood so that they can establish a sound sexual mortality for themselves. Additionally, to perform the sexual education program suitable for every stage of children should be developed, qualified teachers and the educational materials should be reinforced and added enough and institutional device should be made to execute the sexual education program systematically.

• Journal of the Microelectronics and Packaging Society
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• v.30 no.2
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• pp.65-70
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• 2023

Nanoimprint lithography (NIL) has attracted much attention due to its process simplicity, excellent patternability, process scalability, high productivity, and low processing cost for pattern formation. However, the pattern size that can be implemented on metal materials through conventional NIL technologies is generally limited to the micro level. Here, we introduce a novel hard imprint lithography method, extreme-pressure imprint lithography (EPIL), for the direct nano-to-microscale pattern formation on the surfaces of metal substrates with various thicknesses. The EPIL process allows reliable nanoscopic patterning on diverse surfaces, such as polymers, metals, and ceramics, without the use of ultraviolet (UV) light, laser, imprint resist, or electrical pulse. Micro/nano molds fabricated by laser micromachining and conventional photolithography are utilized for the nanopatterning of Al substrates through precise plastic deformation by applying high load or pressure at room temperature. We demonstrate micro/nanoscale pattern formation on the Al substrates with various thicknesses from 20 ㎛ to 100 mm. Moreover, we also show how to obtain controllable pattern structures on the surface of metallic materials via the versatile EPIL technique. We expect that this imprint lithography-based new approach will be applied to other emerging nanofabrication methods for various device applications with complex geometries on the surface of metallic materials.

• The Journal of Korean Physical Therapy
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• v.27 no.6
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• pp.419-424
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• 2015

Purpose: This study aimed to evaluate the effects of lumbar stabilization exercise on the abdominal muscle-back muscle ratio in white-collar workers. Methods: Forty white-collar workers without any pain who worked at an information technology (IT) company located in the Gyeonggi province were included in this study. Of these, 20 subjects were randomly allocated to the lumbar stabilization exercise group, whereas the remaining 20 were randomly allocated to the control group. The lumbar stabilization exercise group performed a 40-minute-long exercise once a week for 8 weeks. The strength of the abdominal and back muscles was measured using the CENTAUR 3-D Spatial Rotation Device (BFMC, Germany). Data analysis was conducted using SPSS 18.0 for Windows. The Paired t-test was performed to compare the values measured before and after exercise within each group. The independent sample t-test was performed to analyze the differences between the 2 groups. The statistical significance for all the analyses was set at .05. Results: The strength of the abdominal muscles after the exercise significantly differed between the lumbar stabilization exercise group and the control group (p<0.05). However, the increase in the abdominal muscle-back muscle ratio was significant in only the lumbar stabilization exercise group (p<0.05), but not in the control group (p>0.05). Conclusion: The improvement of the abdominal muscle-back muscle ratio through lumbar stabilization exercise may have positive effects on lumbar stabilization. Moreover, lumbar stabilization exercise is considered beneficial for the prevention of back pain and musculoskeletal diseases.

• Journal of Chest Surgery
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• v.9 no.2
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• pp.265-270
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• 1976

Implantation of a permanent pacemaker is a widely accepted procedure for the patient with complete heart block.As a result of these device, the prognosis for patients with Adams-Stokes syndrome caused by complete A-V block and other cardiac arrhythmia have become much more optimistic. Permanent pacemaker implantation by means of a transvenous approach has made the operative risk much less and the procedure simpler. However, a number of complications have been reported in the literature regarding transvenous endocardial pacemaker implantation during the last a decade. The patient presented in this paper is a 26-year old girl who was implanted with a permanent pacemaker at 14 years of age because of a congenital A-V block. Following first exchange of pulse generator, the electrode (lead) was fractured, so that by the pulse generator, a change to the transvenous technique of implantation was made, After this, there were episodes of recurrent wound infection on three occasions, even though the site of pulse generator implantation was exchanged to the contralateral side of chest wall, massive doses of antibiotics were administered and sensitivity tests for coagulase positive staphylococcal infection were performed. Though there was no definite evidence of blood stream infection by blood culture, we decided not to use the transvenous technique and not to implant the pulse generator in the chest wall because the venous system and the entire anterior chest wall appeared to be diseased or contaminated by virulent pyogenic organisms. Finally this intractable systemic and local wound infection was successfully controlled by myocardial lead implantation via a subxiphoid approach and implantation of the pulse generator far down in the abdominal wall. The causes and routes of recurrent wound infection and possible blood born infection in this particular patient are still obscure. We strongly believe that myocardial pacemaker implantation is much safer than transvenous endocardial pacemaker implantation & myocardial pacemaker implantation is a definite method for controlling such an intractable wound infection. following transvenous pacemaker implantation.

• Korean Journal of Materials Research
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• v.13 no.5
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• pp.333-337
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• 2003

We report a new fabrication process for carbon nanotube field emitters with high performance. The key of the fabrication process is trim-and-leveling the carbon nanotubes grown in trench structures by employing a planarization process, which leads to a uniform distance from the carbon nanotube tip to the electrode. In order to enable this processing, spin-on-glass liquid is applied over the CNTs grown in trench to have them stubborn adhesion among themselves as well as to the substrate. Thus fabricated emitters reveal an extremely stable emission and aging characteristics with a large current density of 40 ㎃/$\textrm{cm}^2$ at 4.5 V/$\mu\textrm{m}$. The field enhancement factor calculated from the F-N plot is $1.83${\times}$10^{5}$ $cm^{－1}$ , which is a very high value and indicates a superior quality of the emitter originating from the nature of open-tip and high stability of the carbon nanotubes obtained new process.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.7 no.9
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• pp.429-442
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• 2017

This study was performed to investigate and analyze users' needs for m-health based prevention and intervention programs that are intended to improve the awareness of metabolic syndrome and promote health behaviors of college students. A questionnaire survey was conducted to 200 college students of 2 university in D city. Data were analyzed using descriptive statistics, t-tests, chi-square test with the SPSS Version 20.0. The result showed that users wanted customization of prescriptions and accurate measurement of health applications, and provided a positive feedback on information exchange between those who manage their health. The most preferred content was proper exercise methods, and the preferred gamification factors were goal-setting, compensation, and competition. The optimal price for wearable devices was between 10,000 to 50,000 won, and calorie consumption function was also preferred. Although users with experiences of wearable devices and health apps had a higher knowledge score pertaining to metabolic syndrome, there was no significant difference in the overall score. Concerning the health behaviors associated with lifestyles, individuals without the experiences of wearable devices and health apps showed a remarkably lower score. The research has a significance that it investigated and analyzed the contents needed for the development of effective moblie health based prevention and intervention programs targeting the population in their early adulthood. Therefore, based on the findings, we propose a rich and concrete follow-up study on the needs and characteristics of different user types by collecting a population with experiences of wearable devices, and a development of differentiated mobile health based prevention and intervention programs.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.10
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• pp.1189-1193
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• 2012

The Miniaturized Fingerprint Imager (MFI) is a slim optical mouse that can be used as an input device for application to wireless portable personnel communication devices such as smartphones. In this study, we have fabricated key optical components of an MFI, including the illumination optical components and imaging lens. An LED beam-shaping lens consisting of an aspheric lens and a Fresnel facet was successfully machined using a diamond turning machine (DTM). A customized V-shaped groove for beam path banding was fabricated by the bulk micromachining of silicon that was coated with aluminum using the shadow effect in thermal evaporation. The imaging lens and arrayed multilevel Fresnel lenses were fabricated by electron beam lithography and FAB etching, respectively. The proposed optical components are extremely compact and have high optical efficiency; therefore, they are applicable to ultraslim optical systems.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.341-341
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• 2012

Recently, oxide semi-conductor materials have been investigated as promising candidates replacing a-Si:H and poly-Si semiconductor because they have some advantages of a room-temperature process, low-cost, high performance and various applications in flexible and transparent electronics. Particularly, amorphous indium-gallium-zinc-oxide (a-IGZO) is an interesting semiconductor material for use in flexible thin film transistor (TFT) fabrication due to the high carrier mobility and low deposition temperatures. In this work, we demonstrated improvement of flexibility in IGZO TFTs, which were fabricated on polyimide (PI) substrate. At first, a thin poly-4vinyl phenol (PVP) layer was spin coated on PI substrate for making a smooth surface up to 0.3 nm, which was required to form high quality active layer. Then, Ni gate electrode of 100 nm was deposited on the bare PVP layer by e-beam evaporator using a shadow mask. The PVP and $Al_2O_3$ layers with different thicknesses were used for organic/inorganic multi gate dielectric, which were formed by spin coater and atomic layer deposition (ALD), respectively, at $200^{\circ}C$. 70 nm IGZO semiconductor layer and 70 nm Al source/drain electrodes were respectively deposited by RF magnetron sputter and thermal evaporator using shadow masks. Then, IGZO layer was annealed on a hotplate at $200^{\circ}C$ for 1 hour. Standard electrical characteristics of transistors were measured by a semiconductor parameter analyzer at room temperature in the dark and performance of devices then was also evaluated under static and dynamic mechanical deformation. The IGZO TFTs incorporating hybrid gate dielectrics showed a high flexibility compared to the device with single structural gate dielectrics. The effects of mechanical deformation on the TFT characteristics will be discussed in detail.