• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.9
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• pp.907-915
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• 2008

The computational fluid dynamic analysis has been conducted for the thermo-chemical flow field in an arcjet thruster with mono-propellant Hydrazine (N2H4) as a working fluid. The Reynolds Averaged Navier-Stokes (RANS) equations are modified to analyze compressible flows with the thermal radiation and electric field. the Maxwell equation, which is loosely coupled with the fluid dynamic equations through the Ohm heating and Lorentz forces, is adopted to analyze the electric field induced by the electric arc. The chemical reactions of Hydrazine were assumed to be infinitely fast due to the high temperature field inside the arcjet thruster. The chemical and the thermal radiation models for the nitrogen-hydrogen mixture and optical thick media respectively, were incorporated with the fluid dynamic equations. The results show that performance indices of the arcjet thruster with 1kW arc heating are improved by amount of 180% in thrust and 200% in specific impulse more than frozen flow. In addition thermo-physical process inside the arcjet thruster is understood from the flow field results.

• Journal of the Korean Society of Food Culture
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• v.20 no.4
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• pp.476-486
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• 2005

The purpose of this study was to investigate the effects of eating habits and control of overeating of obese children on the body weight control program. The program included nutritional education, psychotherapy and physical exercise on weekly session for 9 months. The results of this study were as follows. Participants of the study involved 30 obese children attending elementary school. The average age of the children was 11.78 years, mean height and weight were 146.22cm and 50.61kg. The average BMI and body fat contents were 24.06 and 30.49% respectively and WHR of the children was 0.87. There was a significant difference between boys and girls' BMI(25.18, 23.31, p<0.01). As a result of the eating habits test, 50% of the subjects showed low level of regularity of diet, and 76.7% of the subjects showed high level of balanced diet score. Large portion(83.3%) of the subjects had high level of healthy behavior score. WHR of girls significantly decreased from 0.86 to 0.82(p<0.01) after the body weight control program. There were no significant differences in serum components of the obese children after the program. When regarding the score of eating habits in relation to obesity indices, the WHR significantly decreased(p<0.05) in a group of children with high eating habits score. Also in the group of overeating controls, significantly decreased WHR(p<0.05). In the results of correlation analysis, body weight was positively correlated with BMI(r=0.624), the level of total cholesterol(r=0.5109) and HDL cholesterol(r=0.5088). The score of healthy behavior was positively correlated with height(r=0.5286) and negatively correlated with the level of LDL cholesterol(r=0.3555) and WHR(r=0.4028) These results suggest that the body weight control program must be considerate of the different groups of children with different scores in the eating habits and overeating controls test.

• Journal of Electrical Engineering and Technology
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• v.10 no.5
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• pp.1921-1929
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• 2015

The smart substation is the heart of a transmission system, which is particularly emphasized as the most significant composition of smart grids in China. In order to assess the functionality performance of substation technologies, this paper presents methods used to identify the most promising solutions for smart substation design and to evaluate the technical levels of available technologies. The multi-index optimization model is presented to address the issue of smart substation planning. A mathematical model of the planning decision problem is established with multiple objectives consisting of economic, reliability, and green key indices, and many kinds of concerns including physical and environmentally friendly operations are formulated as a set of constraints. With respect to the assessment of the technical level regarding integration of advanced technologies into a substation, a modified grey whitenization weight function is adopted to structure a novel grey clustering method. The proposed grey clustering approach is used to overcome the difficulty of insufficient quantitative assessment capacity for traditional methods. The evaluation of technical effects provides the classification definition for the development phase and the maturity level of the smart substation. The effectiveness of the proposed approaches in planning decision-making and evaluation of construction efforts is demonstrated with case studies involving the actual smart substation projects of Wenchongkou substation in China Southern Power Grid (CSG) and Mengzi substation in State Grid Corporation of China (SGCC).

• Journal of Nutrition and Health
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• v.35 no.1
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• pp.124-136
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• 2002

As the elderly population has increased in recent years in Korea chronic degenerative diseases prevalent in the aged have garnered attention in relation to food behavior. In general, dietary intakes of elderly Koreans were inadequate in quality as well as in quantity. Especially, intakes of Ca, vitamin A, and riboflavin along with total energy were insufficient. They tended to consume high carbohydrate and low fat energy rates which may be resulted from long standing vegetable-based flood patterns. Relationships between dietary intakes and indices of cardiovascular diseases revealed that blood pressures and serum lipids patterns tended to be poor in individuals having high abdominal fat accumulations which seemed to be related with dietary consumption of high carbohydrate and insufficient intake of many nutrients. These results suggested that a nutritionally balanced diet including animal sources floods is needed in order to prevent an abdominal obesity and cardiovascular diseases. The bone health status of the Korean elderly appeared poor. It was more serious in women recording a higher prevalence rate of osteopenia and osteoporosis than in men. There were strong associations between dietary factors and bone health status. Bone mineral density was found to be higher with higher intakes of protein energy rate, the total amount of feeds, and many nutrients including Ca and p, indicating that a good quality diet is essential in maintaining healthy bone status in later life. mental health condition of the elderly as measured by cognitive function and the degree of depression was also inadequate and had strong association with dietary consumption. The positive results were obtained in individuals having an adequate dict. Therefore, it could be summarized that the physical as well as mental health in elderly Koreans are highly related with their dietary patterns. Thus, the older adults need te consume nutritionally well balanced diet in sufficient amount, which contains various flood items including significant amounts of animal source floods in a daily diet in order to maintain healthy condition.

• Journal of the Korean Institute of Landscape Architecture
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• v.18 no.4
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• pp.127-140
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• 1991

The Primary purpose of this study is to investigate factors and variables which have significant effects on user satisfaction with recreational facilities in Taejong-Dae recreational complex, thereby establishing indices of planning and development of urban parks and open space. To test the causal models of this research, the date were gathered by self-administered questionnaires from 967 households in Pusan City which were selected by the multi-stage probability sampling methood. The analysis of the multi-stage primarily consists of two phase : The first analysis dealt exploratory factor analysis which identified major factors involved in satisfaction with recreational activities and facilities in Taejong-Dae recreational complex and the second analysis tested the fit of the causal models of this research by employing LISREL methodology. There are three advantages of using LISREL over other multivariate analysis methods : First, measurement error is allowed and calculated in LISREL, otherwise there is a risk of seriously misleading estimates of coefficients ; Second, LISREL deals with latent variables or unmeasured variables ; Third, it enables to test causal relations among variables. The factors analysis identified that five factors are involved in satisfaction with recreational facilities. The five factors of satisfaction with recreational facilities are space for repose and relaxation, active recreation facilities such as pool and zoo, physical exercise facility, convenience and maintenance facility, and linear facility, and linear facility for walking. The second phase analysis tested the fit of the causal models for satisfaction with recreational facilities to the data and identified statistically significant causal linkage among overall satisfaction with Taejong-Dae recreational complex, other endogenous factors and exogenous variables. Overall fits of both causal models were very good. Among endogenous factors, facility for repose and relaxation. linear facility for walking, active recreation facility, facility for convenience and maintenance were identified as having significant effects on overall satisfaction. Exogenous variables which have significant effects on endogenous variables wer also identified. These significant relationships indicate important factors and variables that should be considered in planning and development of the recreational complex. On the basis of these significant causal relationships, implications for planning and the delovepment of Taejong-Dae recreational complex were suggested.

• Journal of Korean Medicine for Obesity Research
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• v.9 no.2
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• pp.21-32
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• 2009

Objectives Identification of individuals predisposed to obesity is an important issue for prevention and control of the obesity. It was reported that a high prevalence of obesity appeared in Taeumin among Sasang constitutions, but Enneagram personality-types has not been used to classify the patterns of obesity. These two classification methods were employed in combination in the current study, and it was analyzed whether the morbidity pattern of obesity can be characterized in further detail. Methods The subjects were 125 University students(62 males and 63 females) who answered both questionnaires for Sasang constitutions and Enneagram personality types. The obesity of students was classified by the obesity index and BMI. Results Only Taeumin group of Sasang constitutions was overweight, and the male of the group was overweight or obese. Analysis of the obesity index and BMI according to the Enneagram personality types showed significant differences(p<.05) between the types in the female group. These values were highest at the type 3 and lowest at the type 4. The physical indices according to both the centers of Enneagram and Sasang constitutions showed that only Taeumin female group had significant differences(p<.05) in the obesity index and BMI. Taeumin male group was overweight or obese in all centers of Enneagram and Taeumin female group was overweight or obese only in heart-center. Conclusions Diagnosis of the present data suggest that the classification of obesity patterns using Enneagram personality types in addition to Sasang constitutions is very useful to prevent and control the obesity.

• Journal of Digital Convergence
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• v.18 no.11
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• pp.387-394
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• 2020

The purpose of this study is to identify walking time, self-efficacy for exercise, sleep quality and depression in order to confirm the relationship between college students' activity level and psychological index. The research method is a cross-sectional descriptive survey of college students. The subjects of this study were 135 students enrolled in colleges in Gyeongbuk. Self-efficacy for exercise was higher than the average, and walking time was about 1.7 hours per day on average, walking less than 2 hours. Sleep quality was most of them had problems with their sleep quality (71.9%). Depression was about half of the students showed a tendency to be depressed (49.6%). It was found that there was a correlation between self-efficacy and depression for exercise (p=.012). This study can be used as basic data for the development of programs to increase physical activity and improve psychological index of college students in the future.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.7
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• pp.42-49
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• 1999

In this paper, we proposed a simple measurement method to find the behaviors of the fiber-to-waveguide coupler. The polished fiber blocks and planar waveguides on silicon dioxide were fabricated independently and then optically coupled by physical pressure. Several kinds of polymer with different refractive indices were used for waveguide films. The proposed method makes it possible to measure the center wavelength, bandwidth, extinction ratio, and polarization dependence of the coupler during fabrication procedure. The wavelength sensitivity increased with refractive index of polymer. The symmetric planar waveguide structure and isotropic property of guiding materials reduced polarization dependent property. Insertion loss of the coupler was less than 0.5dB. It is expected that our measurement method is useful for developing various optical devices using evanescent coupling between polished fiber and planar waveguide such as optical modulators and filters etc.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.14 no.2
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• pp.39-53
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• 2015

The paper analyzes factors to affect pedestrian volumes by land-use type using 2012 Seoul Pedestrian Survey. First of all, five groups were classified based on land-use types around survey points such as residential, commercial, industrial and green uses, using k-average cluster analysis. Then, differences in average pedestrian volumes by group were compared for a day and time of day. In addition, multiple regression analysis was employed to identify factors to affect pedestrian volumes, considering physical features, land use types, public transportation accessibility, and socio-economic indices as independent variables by spatial hierarchy. Model results show that the walkway width positively influenced on pedestrian volumes for all groups, whereas other variables differently affected by group. Our results can be used as basic data for establishing polices with respect to pedestrian road design and improvement as well as estimating pedestrian demand by land-use type.

• Journal of Ecology and Environment
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• v.39 no.1
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• pp.43-49
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• 2016

Fishways are constructed to provide longitudinal connectivity of streams or rivers where their flow has been altered by in-stream structures such as dams or weirs. Nature-like fishways have an additional function of providing fish habitats. In the study, we estimated the role of a nature-like fishway (length: 700 m, slope: 1/100) for fish habitat by using two dominant species in the Sangju Weir, Nakdong River, to calculate the optimal ecological flow rate using Physical HABitat SIMulation (PHABSIM). To identify the dominant species that used the fishway, we conducted trap monitoring from August to November 2012 at the fishway exit. The dominant species were Zacco platypus and Opsariichthys uncirostric amurensis with a relative abundance of 62.1% and 35.9%, respectively. Optimal habitat suitability indices (HSIs) for Z. platypus and O. u. amurensis were calculated as 0.6-0.8 m/s (water velocity) and 0.2-0.4 m (water depth), and 0.5-0.7 m/s (water velocity) and 0.1-0.3 m (water depth), respectively. The optimal ecological flow rates (OEFs) for Z. platypus and O. u. amurensis were 1.6 and 1.7 cubic meter per second (CMS), respectively. The results of the study can be used in a management plan to increase the habitat function of nature-like fishways in the Sangju Weir. This methodology can be utilized as an appropriate tool that can determine the habitat function of all nature-like fishways.