• Journal of ILASS-Korea
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• v.22 no.4
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• pp.210-217
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• 2017

A gasoline direct injection engine has an intake air temperature can be lowered by the fuel vaporization in the combustion chamber increase the volume efficiency is high compression ratio. Therefore, study for injection rate and characteristics which influence mixture formation in combustion chamber is important. Movement of the injector needle has a direct effect on the injection of the fuel, such as formation of cavitation, the fuel injection rate, etc. Therefore, recent studies on the dynamic characteristics of the injector considering the movement of the needle have been reported, but it takes a lot of time and cost to experimentally confirm the movement of the needle inside the injector. In this study, AMESim, a commercial 1-D code, and Star-CCM+, a 3-D CFD code, were used to predict the dynamic performance of the injector with needle motion. In order to predict the movement of the needle under the high pressure, the result of the surface pressure distribution according to the movement of the needle was derived by using the morphing technique of flow analysis. In addition, we predicted the injection rate of the injector considering the movement of the needle in conjunction with the 1-D code. The injection rate of the injector was measured by the BOSCH's method and the results were similar to those of the simulation results. This method can predict the injection rate and injection characteristics and this result is expected to be used to predict the performance of gasoline direct injection engines with low cost and time in the future.

• Journal of the East Asian Society of Dietary Life
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• v.18 no.1
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• pp.127-134
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• 2008

This study was designed to evaluate the nutritional status and dietary problems of obese elementary students consuming unbalanced diets. Blood parameters, body-image perceptions, taste preferences, and nutrient intakes of 40 obese elementary students with unbalanced diets were compared to those of 40 additional obese elementary students as a control. The averages for age, height, weight, and obesity index were 11.5 years, 142.0 cm, 51.0 kg, and 35.4% in the study group and 11.8 years, 144.0 cm, 53.5 kg, and 36.3% in the control group, respectively. The major disliked foods by the students in the study group were vegetables (65%) particularly Kimchi (15%), as well as fish(15%), and pulses (10%). Mean serum cholesterol, blood glucose, GOT/GPT, and hemoglobin levels were 175.1 mg/dL, 89.2 mg/dL, 24.1/18.9 IU/L, and 14.3 g/dL in the study group and 182.8 mg/dL, 91.3 mg/dL, 28.3/33.9 IU/L, and 14.7 g/dL, in the control group, respectively. Approximately 60${\sim}$80% of the subjects responded that they eat a meal everyday, and the remainder skipped at least one meal. The preference for salty tasting foods was significantly lower in the study group, but the preference for hot tasting food was higher as compared to the obese control group(p<0.05, p<0.05). The daily energy intakes of the study and control groups were 1,768.3 kcal and 1,572.7 kcal, respectively, but there was no significant differences between them. Daily intakes of animal protein, fat, animal fat, and vitamin $B_2$ were significantly higher in the study group than in the control group. In conclusion, this study found that obese children consuming unbalanced diets strongly disliked vegetables, particularly Kimchi, as well as hot tasting foods; however, they preferred salty foods. Daily intakes of animal protein and fat were higher in the study group as compared to obese children not consuming unbalanced diets.

• Journal of the East Asian Society of Dietary Life
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• v.22 no.4
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• pp.452-462
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• 2012

The study was conducted to investigate the dietary behaviors and lifestyles of Korean university students and Chinese international students in the Jeonbuk area. Self-administered questionnaires were collected from 241 Korean university students and 198 Chinese international students. Statistical data analysis was completed using SPSS v. 12.0. Breakfast-skipping among subjects was very common, and the most frequently given reason for skipping this meal was 'lack of time'. More than 85% of Korean male students and 75% of Korean female students reported regularly eating lunch in university canteens or restaurants around campus, whereas 86% of Chinese male students and 82% of Chinese female students regularly ate their lunches in university canteens or at home. About 62% of Korean male students, 72% of Korean female students, 48% of Chinese male students, and 70% of Chinese female students responded that they do not regularly eat dinner, the main reasons cited for this being 'irregularity of lifestyle' and 'part-time work'. Snack intake by the subjects was high. Beverages were the snack item most frequently consumed by Korean and Chinese male students, whereas cookies and fruits were most frequently consumed by Korean and Chinese female students. About 28% of Korean male students and 44% of Chinese male students were smokers, respectively. Half of Chinese female students drank alcohol once or twice a week. About 42% of Korean male students and 65% of Chinese male students played sports, respectively. Dietary behaviors and lifestyles of Korean and Chinese students tended to be very similar. Chinese students performed more health-oriented activities in comparison to Korean students. In conclusion, a practical and foreigner-friendly nutritional education program should be devised in order to correct the dietary behaviors and health-related lifestyles of Korean and Chinese students.

• Journal of the East Asian Society of Dietary Life
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• v.24 no.5
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• pp.552-563
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• 2014

This study was performed to investigate the dietary habits and nutritional knowledge of elementary school students (boy : 250, girl : 250) by gender. Frequency of skipping breakfast was high in both boys and girls. Duration of mealtime was significantly higher for boys compared with girls (p<0.001). Regularity of meals was not significantly different between boys and girls. Reason for irregular meals was 'no appetite' for both boys (39.6%) and girls (40.0%). Unbalanced diet was high in both boys (60.8%) and girls (59.6%), and problems related to dietary habits were in order of 'unbalance diet', 'irregular mealtime', 'overeating', 'skip a meal frequently', and 'eat out frequently'. Frequency of snack intake was significantly higher for girls compared to boys(p<0.05). The criterion for selecting snacks was higher for 'nutrition' compared to 'good taste' for both boys and girls. Frequency of eating out was statistically insignificant, and eating out preferences were in the order of 'Korean food', 'western food', and 'Chinese food'. Eating behavior 'eat meat, fish, egg, tofu every meal' was significantly higher for boys compared to girls (p<0.01). 'Healthful' response rates were 57.6% for boys and 58.8% for girls. Practice level of nutritional knowledge was significantly higher in girls compared to boys (p<0.001). To establish good eating behaviors, we should develop systematic and continuous education programs.

• Journal of Korean Public Health Nursing
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• v.22 no.1
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• pp.5-17
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• 2008

Purpose: To understand the dietary habits and factors influencing the dietary habits in adults of an urban community. Method: The data were collected via questionnaires that investigated dietary habits, health behaviors, health-related factors, and general characteristics. A total of 302 subjects were selected from those who had visited an urban public center over a 2-week period. The data of 294 subjects were analyzed using descriptive analysis, t-test, ANOVA, and multiple regression, after 8 questionnaire were excluded due to incomplete data. Results: The degree of dietary habits was in the middle range. The most positive dietary habit was 'intake fibers from vegetables, fruits, and cereals', followed by 'not enjoy salty food and salt' and 'eating breakfast everyday'. The significant predictors influencing dietary habits were age, present smoking behavior, perceived health status, and drinking frequency, and these variables accounted for 27.3% of the variance in the dietary habits score. Conclusion: Health care providers should focus on health promotion planning regarding dietary habits and other health-related behaviors in combination and use integrated strategies regarding the factors that influence dietary habits and other health-related behaviors.

• Journal of the Korean Home Economics Association
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• v.33 no.3
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• pp.225-242
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• 1995

This study was undertaken to review the relationship between middle-school students' food-behavior and their health conditions/school performances. For this purpose, 495 male and female middle-school students were sampled form seven middle schools located in Seoul for a questionnaire survey. The surveyed data were analysed with simple frequency, percentage, t-test, chi-square test, dispersion analysis, Pearson's correlation and hierarchical multiple-regression analysis which make use of the SPSS/PC+ package system. The results of survey can be summarized as follows; Most of students had three meals a day regularly, but some female students used to skip breakfast or supper. The amount of a mael was adequate. Their main night-smacks were fruits. The problem perceived by students was unbalanced meal ; Female students took more snack than that of male students. They usually took a snack a day. All students tended to take delicious snacks. The most favorate smack of students was fruits. Most students did not suffer any serious diseases, but some had one or more respiratory diseases. Female students had some or other physical troubles in their eyes, mouth, digesting organs, muscle/bone, skin and had fatigue. Female students had mental problems of depression, uneasiness and hostility. The average I.Q. of students was 117.4, and those who had higher I.Q. got much higher scores. The regularity and amount of meal and intake of animal food were all positively related with the growth of height and weight. And the taller, the higher I.Q. they had. Those students who took meals three times regularly and adequately, who had no coffee and snack and who took balanced meals were healthier in both physical and mental terms. In particular, those who had adequate amount of breakfast regularly were not only healthier but also had higher I.Q. and school performance.

• Korean Journal of Rural Living Science
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• v.9 no.1
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• pp.19-31
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• 1998

The purpose of this study was to compare the consciousness health status and food habit for farmers in Korea. Eight hundred persons were surveyed by rural leader of RDA, composed with 35.1% of male and 64.9% of female. Data collection includes height weight and blood pressure by measuring method and personal & family situation by interview for influential factor of health status and food habit. The questionnaire was included dietary habit of salt, sugar, dietary fiber and fat intake and other behavior questions related with diet. The subjects were composed 32.5% of elementary school graduated and 50% of middle size farming. Of the all subjects, 54% of were rice planted farming mainly and 19 were over 65 year-aged group. In the concept of disease prevalence. gender difference was exist, liver and heart complains were more frequency in male and waist pain and urinary complain in female, shoulder pain and nervousness were frequently prevalent to all group of farmers. The hypertension prevalence of farmers were 16% by measuring blood pressure, but consciousness of hypertension was very low (5%). The correlation of health status with personal factors were analysed, body weight, number of family, education level, and working level were significant with CMI score and Farmers' syndrome score. The food habit status was negatively correlated with weight and BMI, age was negatively correlated with CMI score and farmers' syndrome. The consciousness of health status and food habit score were significantly correlated with smoking and alcohol drinking. It concludes that good food habit contribute wellness of health. Nutrition education for better food habit would be helpful on health status.

• Journal of dental hygiene science
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• v.20 no.1
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• pp.44-50
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• 2020

Background: Smartphones are a modern necessity. While they are convenient to use, smartphones also have side effects such as addiction. This study assessed the relationship between smartphone use, a part of everyday life in modern society, and oral health. Methods: An analysis was conducted using 2017 Korea Youth Risk Behavior Web-based Survey data. The propensity score estimation algorithm used logistic regression and 1:1 matching algorithm using nearest-neighbor matching. After matching, a total of 15,032 participants were classified into two groups containing 7,516 teenagers each who did and did not use smartphones, respectively. Results: Comparison of oral health behaviors according to smartphone use revealed a statistically significant difference in the frequency of tooth brushing per day, use of oral hygiene products, intake of foods harmful to oral health, and experience of oral health education (p<0.05). The factors affecting oral pain experience of adolescents were examined. Compared to male participants, female participants had an odds ratio of 1.627 for oral pain (p<0.05). According to the household income level, compared to the group with higher income, the group with lower income showed higher oral pain experience (p<0.05). Oral pain experience was 1.601 times more frequent among teenagers using smartphones (p<0.05). Conclusion: The results of this study indicated that use of smartphones by adolescents affected their oral health. These findings indicate the need for improved oral health management through the use of effective school oral health programs and individual counseling by oral health professionals, promotion of information dissemination through public media, and development of prevention strategies.

• Korean Journal of Community Nutrition
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• v.17 no.2
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• pp.205-214
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• 2012

This study examined intakes of nutrients, carotenoids and polyphenols according to lens turbidity levels among adults visiting a cataract clinic. A total of 102 males and females aged 40 years or higher agreed to participate in the study, and a face-to-face survey interview was conducted to obtain information on general characteristics, health behaviors, and dietary intakes of each participant. The dietary data were collected by a food frequency questionnaire which was previously validated in a Korean population. In addition to essential nutrients, intakes of a total of 10 carotenoids and polyphenols were calculated based on the tables of food functional composition developed by National Academy of Agricultural Science. The subjects were divided into 3 groups according to turbidity levels (< 16, ${\geq}16$ and < 25, ${\leq}25$), and health behaviors and dietary intakes were compared among the turbidity groups. Data showed seemingly higher energy intake and lower dietary antioxidant (i.e., vitamin A, ${\beta}$-carotene, lutein, zeazanthin, lycopene, cryptozanthin) intakes in the highest turbidity group. However, no statistically significant findings were found in all the comparative analysis on characteristics of health behavior and intakes of nutrients, carotenoids and polyphenols. The current study findings should be cautiously interpreted in consideration of several limitations including a cross-sectional study design, a small sample size, uneven sample size distribution across turbidity groups, and limited generalizability due to using a convenience sample. Therefore we cannot conclude that the risk of cataract is unrelated with dietary antioxidant intakes based solely on the results of this study.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.848-853
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• 2004

Regarding to the project SUAV (Smart Unmanned Aerial Vehicle) in KARI (Korea Aerospace Research Institute), several engine configurations has been evaluated. However it's not an easy task to collect all the necessary data of each engine for the analysis. Usually, some kind of modeling technique is required in order to determine the unknown data. In the present paper a qualitative method for reverse engineering is proposed, in order to identify some design patterns and relationships between parameters. The method can be used to estimate several parameters that usually are not provided by the manufacturer. The method consists of modeling an existing engine and through a simulation, compare its transient behavior with its operating envelope. In the simulation several parameters such as thermodynamics, performance, safety and mechanics concerning to the definition of operation-envelope, have been discussed qualitatively. With the model, all engine parameters can be estimated with acceptable accuracy, making possible the study of dependencies among different parameters such as power-turbine total inertia, TIT, take-off time and part load, in order to check if the engine transient performance is within the design criteria. For more realistic approach and more detailed design requirements, it will be necessary to enhance the compressor map first, and more realistic estimated values must be taken into account for intake-loss, bleed-air and auxiliary power extraction. The relative importance of these “unknown” parameters must be evaluated using sensitivity analysis in the future evaluation. Moreover, fluid dynamics, thermal analysis and stress analysis necessary for the resulting life assessment of en engine, will not be addressed here but in a future paper. With the methodology presented in the paper was possible to infer the relationships between operation-envelope and engine parameters.