• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.11
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• pp.981-987
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• 2014

DC/DC switching power converters are commonly used to generate a regulated DC output voltage with high efficiency. The DC/DC converter is composed of a MOSFET (metal-oxide semiconductor field effect transistor), a PWM-IC (pulse width modulation-integrated circuit) controller, inductor, capacitor, etc. It is shown that the variation of threshold voltage and the breakdown voltage in the electrical characteristics of MOSFET occurs by radiation effects in TID (Total Ionizing Dose) testing at the low energy ${\gamma}$ rays using $^{60}Co$, and 5 heavy ions make the gate of MOSFET broken in SEGR (Single Event Gate Rupture) testing. TID testing on MOSFET is accomplished up to the total dose of 40 krad, and the cross section($cm^2$) versus LET(MeV/mg/$cm^2$) in the MOSFET operation is studied at SEGR testing after implementation of the controller board.

• Journal of the Korean Society of Radiology
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• v.11 no.3
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• pp.101-108
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• 2017

DC/DC switching power converters are commonly used to generate a regulated DC output voltage with high efficiency. The advanced DC/DC converter uses a PWM-IC with OP-Amp. (Operational Amplifier) to control a MOSFET (metal-oxide semiconductor field effect transistor), which is a switching component, efficiently. In this paper, it is shown that the electrical characteristics of OP-Amp. are affected by radiations of ${\gamma}$ rays using $^{60}Co$ for TID (Total Ionizing Dose) testing and 5 heavy ions for SEL (Single Event Latch-up) testing. TID testing on OP-Amp. is accomplished up to the total dose of 30 krad, and the cross section($cm^2$) versus LET($MeV/mg/cm^2$) in the OP-Amp. operation is evaluated SEL testing after implementation of the controller board.

• Journal of dental hygiene science
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• v.12 no.6
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• pp.583-590
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• 2012

The purpose of this study was to investigate effect of the economic stress and state-trait anxiety on the periodontal disease in order to prevent the occurrence and progression of periodontal disease. Date were collected from total of 326 subjects in their forties and fifties by using questionnaire and examination of periodontal states during the period from February to November 2011. Results were analyzed by using frequency, t-test, ANOVA and Multiple regression of SPSS ver. 19.0. 1. The economic stress were significant statistically to the higher, medium and low of gingival index (p<0.01). 2. The state-trait anxiety were significant statistically to the higher, medium and low of gingival index (p<0.001), of the pocket depth (p<0.05), of the clinical attachment loss (p<0.05). 3. The gingival index were investigate effect of the higher the economic stress ($\beta$=0.052, p<0.01), the higher the state-trait anxiety ($\beta$=0.052, p<0.01). As a result, this study suggests that the dental clinic institute needs to let the patients with the periodontal disease know about the effects of economic stress and state-trait anxiety. They also necessarily need to implement education program including stress management, economic stress, and state-trait anxiety improvement in order to prevent periodontal disease and to take charge.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.455-458
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• 2006

This study has numerically modelled the combustion processes of the turbulent swirling premixed lifted flames in the low-swirl burner (LSB). In these turbulent swirling premixed flames, the four tangentially- injected air jets induce the turbulent swirling flow which plays the crucial role to stabilize the turbulent lifted flame. In the present approach, the turbulence-chemistry interaction is represented by the level-set based flame let model. Two-dimensional and three-dimensional computations are made for the various swirl numbers and nozzle length. In terms of the centerline velocity profiles and flame liftoff heights, numerical results are compared with experimental data The three-dimensional approach yields the much better conformity with agreements with measurements without any analytic assumptions on the inlet swirl profiles, compared to the two-dimensional approach. Numerical clearly results indicate that the present level-set based flamelet approach has realistically simulated the structure and stabilization mechanism of the turbulent swirling stoichiometric and lean-premixed lifted flames in the low-swirl burner.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.77-80
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• 2017

One of the fundamental limits of Bluetooth Low Energy(BLE) is that the data transmission is available via singlehop connection. In this research, we suggested the stable multihop transmission method to overcome this limitation. In multihop connection situation, multiple singlehop connection should be made and disconnected dynamically. Therefore, we stored the data within the GATT layer and tried to send it dynamically. We divided whole process as 4 states, and let each nodes transfers around each states to make data connection safely. Also, we set the transfer policy between each states during the transmission to make a robust system. From the experiment in real-time environment, we proved that our method showed high rate of packet delivery in a multihop network, which consists of more than 3 nodes.

• Journal of the Korean Institute of Rural Architecture
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• v.25 no.3
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• pp.27-35
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• 2023

This study aims to provide implications for Korea's efficient application policies for closed schools by identifying the current status of how closed schools are revitalized in Japan and their supportive measures. In Japan, a total of 2,215 schools have closed from 1992 to 2001, and 8,580 schools from 2002 to 2020, with 10,709 closures occurring from 1992 to 2020. The average number is about 369 per year. In terms of the overall trend, the number of closed schools have been put into use and the numbers have increased from 70% in 2013 to 74% in 2020. To summarize the characteristics of the use, first, there is a complex phenomenon in which the use of closed schools are becoming more diverse. Second, closed schools are most often revitalized as educational facilities for residents, followed by social sports facilities, social education facilities and cultural facilities. Third, the use of closed schools in the industries are increasing as they are used as "corporal facilities and start-up support facilities". In order to promote the use of closed schools, the Ministry of Education, Culture, Sports, Science and Technology in Japan promoted the simplification and elasticity of property disposal procedures in 2008. Since 2010, the disclosure of information on closed facilities and matching service between providers and users have been unified through the "Let's Connect to the Future ~ Closed School for All" project. The Cabinet Office including the four offices, and five central governments are advocating the use of closed schools by promoting subsidy support projects.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.12
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• pp.7068-7076
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• 2014

This study examined differences in beauty majors' career maturity and career decision-making depending on the grade and analyzed the relationship between the career maturity with the career decision-making to present basic data for guidelines that would help any relevant field with their career consultations and education targeting those students majoring in beauty at college. A total of 336 beauty majors in the metropolitan area were selected as the research subjects. The study confirmed that the higher the grade, the greater the career maturity. The students who had a higher level of career maturity tended to be included in the reasonable career decision-making category while those students with a lower level of career maturity were determined to conduct dependent decision-making. In terms of the career decision, the students in the higher grades were reasonable enough to make decisions logically because they collect various information through systematic stages but when it comes to the students in the lower grades, they were divided into the intuitive type that would reach a decision through emotional self-recognition depending on how one feels at this moment or what situation one is going through as well as the dependent type that would let people or environments influence one's decision-making. The grades of the students tended to cause differences in the career maturity and the career decision-making, and the significance between the two variables was proven. If the relevant fields carry out systematic grade-focused programs and career guidance not only to improve the career maturity of even the lower graders but also to encourage the students to make reasonable decisions, such programs and career guidance will be a help when the students try to determine a career.

• Journal of The Korean Association For Science Education
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• v.22 no.3
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• pp.560-570
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• 2002

This study was focused on whether secondary science teachers have consistent, integrative scheme on the definition of atmospheric pressure and phenomena caused by air pressure. We had made questionnaire and let 94 science teachers answer. We sorted the responses according to their major, school and compared them with the description in textbooks. The result can be summarized into three findings. First of all, teachers whose major is chemistry have strong tendency to understand that atmospheric pressure is caused by molecular motion though it, in textbooks, is defined as the pressure by weight of air mass. The half of respondents believed that decreasing of atmospheric pressure in high altitude is due to molecular motions, while most textbook says decrease in the weight of air mass. Secondly, many science textbooks show that air mass expands, rises, becomes less dense and the pressure of atmosphere becomes low when it receives heat. So, most of respondents explained low pressure is formed by lower density. Thirdly, they answered that they just teach the phenomena of air pressure by using the textbooks which mainly deal with the present state rather than a principle. In conclusion, the science textbooks should present the exact description and consolidated structures of those concepts to prevent students from having misconceptions on air pressure. In addition, training program for science teachers would be necessary to reconsider and explore the natural phenomena in various viewpoints.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.05a
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• pp.130-133
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• 2002

As a society advances, an aging phenomenon and many diseases which did not exist in old times are happening. Especially, in case of the aged patient, because we cant know the time the condition of the patients health become worse, the study of the Tele-information system has been actively carried out by the necessity of a persistent observation. A ECG signal a kind of a vital signals has been widely used to the medical information system as an usual clinical diagnosis for the patients who possess heart diseases. BlueTooth is a close range wireless communication technology which uses a wireless frequency 2.4GHz and has a high trust and self - error correction technology according to a low power consumption quality and a high-speed frequency hopping. This makes get a high trust concerning a data transmission than an existing modem. In addition, though wireless modem is restricted by a minimal of a wireless terminal, It will be possible to coincide with the function of the portable with the low power consumption quality by using Bluetooth. And as the system on a chip of module progresses, the possibility of the small size is present According to this, Bluetooth module transmits the medical information, which is input from the outside among the operations that use the Bluetooth to the Bluetooth module that is connected the host PC. And the system that the host PC transmits the medical information from the connected Bluetooth module to the Internet has once embedded. this study let the host PC embedded in advance of the existing system and transmit the medical information by the addition of the Tcp/Ip protocol stark under all embedded environments to internet.

• The Journal of the Korea Contents Association
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• v.17 no.6
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• pp.71-80
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• 2017

The standards for achievement levels for building blocks in elementary geometry class is to enhance spatial cognitive ability through practices describing shape patterns of building blocks observed from different directions. However, most of building block in the textbook is described from only one perspective. Even worse, some examples in the textbook are almost impossible to observe in the real world. Contrary to this, simulated views by Wings3D has shown that each box may look quite differently from different angles let alone the size of each box. Using Wings3D, it is also very easy to build different types of building blocks with various levels of difficulty in the virtual space. Based on these results, in this study, 3D visualization SW is suggested as a potential pedagogical tool for the elementary geometry class to help kids perceive objects in space more precisely. We have shown that 3D visualization SW such as Wings3D could be a powerful, compact 3D SW for most of subjects which are covered in elementary geometry education. Wings3D has another advantage of economic open source SW fully compatible with school PCs.