• Journal of radiological science and technology
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• v.15 no.2
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• pp.25-30
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• 1992

With transmitted dose through chest which has the problem of wide variations in absorption, simple film/screen combination method makes it diffucult to image lung field, mediastinum and retrocardiac areas. In order to overcome this, it is very common to use the high kilovoltage technique in diminishing the differences between high and low contrast. We have been adopting this method at department of diagnostic radiology, Seoul National University Hospital. To compare the image of it with that of low kilovoltage technique, we did radiographic tests using beans on the skin. We marked off into three anatomical categories such as lungs, mediastinum and near diaphragm, then attached a bean on a marked area at random. In order to compare with high and low, we took a radiography of high($120{\sim}140\;kVp$) and low($70{\sim}90\;kVp$) kilovoltage tehchniques, respectively at the same time. We have done experiments 320 cases. We evaluated the results of test in response to sensitivity(true positive) and specificity(true negative). In evaluating, we gave them points from 1 to 5 according to true or false. With given points by a radiologist having much experiences, we could acquire the percentage of sensitivity and specificity. The percentage made us to get the schematic table of ROC curve of those two methods. Consequently, high kilovoltage technique appeared 18% better than low kilovoltage technique for detecting beans with our apparatus.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.372-377
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• 2007

For more than 2,500 years, surgical teaching has been based on the so called "see one, do one, teach one" paradigm, in which the surgical trainee learns by operating on patients under close supervision of peers and superiors. However, higher demands on the quality of patient care and rising malpractice costs have made it increasingly risky to train on patients. Minimally invasive surgery, in particular, has made it more difficult for an instructor to demonstrate the required manual skills. It has been recognized that, similar to flight simulators for pilots, virtual reality (VR) based surgical simulators promise a safer and more comprehensive way to train manual skills of medical personnel in general and surgeons in particular. One of the major challenges in the development of VR-based surgical trainers is the real-time and realistic simulation of interactions between surgical instruments and biological tissues. It involves multi-disciplinary research areas including soft tissue mechanical behavior, tool-tissue contact mechanics, computer haptics, computer graphics and robotics integrated into VR-based training systems. The research described in this paper addresses the problem of characterizing soft tissue properties for medical virtual environments. A system to measure in vivo mechanical properties of soft tissues was designed, and eleven sets of animal experiments were performed to measure in vivo and in vitro biomechanical properties of porcine intra-abdominal organs. Viscoelastic tissue parameters were then extracted by matching finite element model predictions with the empirical data. Finally, the tissue parameters were combined with geometric organ models segmented from the Visible Human Dataset and integrated into a minimally invasive surgical simulation system consisting of haptic interface devices and a graphic display.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.188.2-188.2
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• 2011

The use of renewable energy sources is becoming increasingly necessary to minimize the problems derived from the global warming impacts caused by the utilization of fossil fuels as well as their limited supply and reservoir. Also, localized heavy rain has occurred in many areas. As a result, suspended wood waste is being inflow into the dam and the problem of waste disposal has occurred. It is a unique renewable and alternative source for the production of energy. The experiment using wood waste (dry weight 25.0g) was conducted for extraction sugars such as xylose, lactose and glucose. For the sugar extraction from wood waste, hydrolysis experiment using wood waste was conducted by two steps. First step was reacted with 72% sulfuric acid (24.0N and 37.5 ml) for 1hr at $30^{\circ}C$ and second step was reacted at $105^{\circ}C$ for one hour after adding 2.45times of hot water. Extracted sugar was used in the experiment of sugar consumption to estimate feasibility of ethanol production using yeast(P. Stipitis and S cerevisiae). As a result, sugar extracted from wood waste was effective consumed by yeast(P. Stipitis and S cerevisiae). The consumption rate by yeast was S. cerevisiae was faster than that of P. stipitis. It can be confirmed that resource as ethanol production using wood waste was available.

• Journal of Community Nutrition
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• v.3 no.2
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• pp.103-109
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• 2001

With a continuous and steep increase in life expectancies, Korean society is expected to enter the aged society by year 2020. And as the number of elderly increases, the burden of medical and health care expenses for them becomes greater in every developed society. Hence, the preventive approach for chronic degenerative diseases remains to be the best solution for the above-mentioned problem and warranting optimal nutrition would be one of the most important approaches. We performed a nutrition survey on 585 older adults of 50 years of age and older, residing in 3 metropolitan areas including Daejun, Daeku and Kwangju. Anthropometry, including body composition analysis based on the bioelectrical impedance analysis using InBody 3.0 and dietary intake survey by semi-quantitative flood frequency questionnaires, were used in collecting data. As one of the most important factors affecting the health and nutritional status of the elderly, we focused on living arrangements. Analyses were performed on the data from 550 subjects only, after excluding statistical outliers. Three hundred and sixty-eight of them(66.9%) were female and the number of elderly(65 years of age and older) was 485. According to the statistical analyses, the female elderly were more vulnerable to malnutrition than the male elderly. And the older they befame, the less adequate they were in nutrient intake. In addition to this, the elderly living alone showed the poorest patterns of nutrient intake and anthropometry. Although the exact effect of living alone could differ among different sex-age groups, the fact that the elderly living alone is vulnerable to malnutrition would remain concrete. This raises the utmost necessity of nutrition intervention to be devised and directed to the targeted population, namely the living-alone elderly from the government level. The intervention may include nutrition education, nutrition counseling and support In forms of meal service by networking the efforts of central as well as local governments to ensure the good health of the Korean elderly.

• Korean Journal of Community Nutrition
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• v.15 no.2
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• pp.169-179
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• 2010

Good snack consumption behaviors are important among elementary students because snack provides additional energy and nutrients and because good dietary behaviors should be formed during early stages of life. This study investigated, among elementary school students, 1) snack consumption behaviors, 2) snack-related nutrition knowledge level, and 3) relationships between snack behaviors and snack-related nutrition knowledge. A convenience sample (N = 372), drawn from 5th and 6th graders of an elementary schools in Siheung-si, Gyeonggi-do, completed a pre-tested questionnaire. More than 85% of the participants snacked more than once per week. Most (77%) had their snacks at home. Fruit and fruit juice were the most frequently consumed and the most liked snack items. Taste was the most important in choosing a snack item closely followed by health/nutrition. Snack-related knowledge level was relatively high and the participants obtained their nutrition knowledge through mass media (30.4%) and family/friends (29.0%). Snack-related nutrition knowledge level and snack consumption behaviors showed positive relationships in various areas such as choosing more nutritious snack items and checking nutrition labels. Although this study was limited by its cross-sectional study design, these positive relationships suggest that better nutrition knowledge could result in better behaviors. Results of this study indicated that factual nutritional knowledge has been well transmitted to students. Therefore, future nutrition education on snacking could focus more on providing problem-solving and operational knowledge.

• Journal of Korean society of Dental Hygiene
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• v.6 no.1
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• pp.63-77
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• 2006

The purpose of this study was to prepare a student and education guideline by examining the college life satisfaction of students studying dental hygiene. Subjects were students going to dental hygiene-related department of three colleges in the Gwangju and Jeonnam areas. College life and life satisfaction was examined at general characteristics. The following results were obtained. 1. Subjects included 35.7% of 1st grade, 33.4% of 2nd grade, and 30.9% of 3rd grade. In the health state, average accounted for the highest percent(76.9%); in the student's associates, a little for the highest percent(76.8%); and in the participation in clubs, no participation for the highest percent(77.1%). 2. For motives to select the dental hygiene, good employment after graduation accounted for the highest percent(61.0%). The highest desired employer was a dental clinic(33.5%), and the highest desired duration was a whole life(61.0%). 3. According to the grade, satisfaction was significantly different in social recognition, major in education, professor, facilities, professor-student, career, and college development(pE0.05). 4. According to the school record, satisfaction was significantly different in social recognition, major in education, professor, professor-student, career, college development, and general life(pE0.01). 5. According to the student's associates, satisfaction was significantly different in social recognition, major in education, professor-student, and general life(pE0.01). 6. According to the participation in clubs, satisfaction was significantly different in professor, facilities, college development, and religious life(pE0.05). In conclusion, as students were in the lower grade, made good school record, had happier associates, and participated in clubs more actively, their satisfaction at college life became higher. Accordingly, professors and school authorities should strive to examine students' actual problem and discuss and resolve them in order to help their effective school life.

• Journal of Energy Engineering
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• v.27 no.2
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• pp.32-48
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• 2018

Monitoring of energy use should be a priority in order to efficiently manage building energy use. Energy use in buildings can be managed by dividing them into energy sources, uses, and ZONE. By energy source, electricity, gas, fuel, and district heating are supplied to run the building's facilities. The purpose can be divided into five main applications, including cooling, heating, lighting, hot water and ventilation, but not many elevators and electric heaters that are difficult to include in the five applications are classified. ZONE Star refers to the comparison or separate management of areas for which the purpose of the building is similar or different. In addition, energy efficiency management requires control of the temperature, humidity, and people who will be measuring energy in the building, and the recent problem of fine dust should directly affect the ventilation of the building.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.8
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• pp.1163-1171
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• 2017

The problem of fault current to exceed the rated capacity of a power circuit breaker can cause a serious accident to hurt the reliability of the power system. In order to solve this issue, current limiting reactors and circuit breakers with increased capacity are utilized but these solutions have some technical limitations. Back-to-back high voltage direct current(BTB HVDC) may be applied for reducing the fault current. When BTB HVDCs are installed for reduction in fault current, selecting the optimal location of the BTB HVDC without causing overload of line power becomes a key point. In this paper, we use genetic algorithm to find optimal location effectively in a short time. We propose a new methodology for determining the BTB HVDC optimal location to reduce fault current without causing overload of line power in metropolitan areas. Also, the procedure of performing the calculation of fault current and line power flow by PSS/E is carried out automatically using Python. It is shown that this optimization methodology can be applied effectively for determining the BTB HVDC optimal location to reduce fault current without causing overload of line power by a case study.

• Journal of KIISE
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• v.44 no.6
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• pp.607-612
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• 2017

This paper presents an attempt to apply Deep Learning technology to solve the problem of forecasting floods in urban areas. We employ Recurrent Neural Networks (RNNs), which are suitable for analyzing time series data, to learn observed data of river water and to predict the water level. To test the model, we use water observation data of a station in the Trinity river, Texas, the U.S., with data from 2013 to 2015 for training and data in 2016 for testing. Input of the neural networks is a 16-record-length sequence of 15-minute-interval time-series data, and output is the predicted value of the water level at the next 30 minutes and 60 minutes. In the experiment, we compare three Deep Learning models including standard RNN, RNN trained with Back Propagation Through Time (RNN-BPTT), and Long Short-Term Memory (LSTM). The prediction quality of LSTM can obtain Nash Efficiency exceeding 0.98, while the standard RNN and RNN-BPTT also provide very high accuracy.

• The Journal of the Korea Contents Association
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• v.11 no.12
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• pp.578-585
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• 2011

Nowadays, wireless local area networks are widely deployed so that stations can potentially associate with an access point. The AP selection strategy is one of the significant research areas for wireless local area networks. The selection strategy solves the relevant problem is which AP can be selected and associated with a station so that the efficient resource utilization can be obtained. Rather than merely choosing the AP with the strongest received signal strength, however, we calculate effective throughput for each neighboring AP and use it as a basis for AP selection. Referencing the throughput is better than referencing the signal strength only because the network may contain a severe load imbalance. We have performed computer simulations using OPNET modeler in order to verify the performance of the proposed scheme. The results show us that the proposed selection method outperforms that of the conventional one in terms of throughput and delay.