• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.19-23
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• 1998

Water tree degradations have been considered as one of the most important causes of failure in underground distribution cables with polymeric insulation. Water tree growth is a preliminary step in the sequence of electrical tree initiation and electrical breakdown of the insulation. In this paper, needle electrode is made use of the etching methods and the pellet type specimen is made to observe the water tree in succession. In previous methods are able to observe the tree degradations without cutting and dyeing. The water tree image is recorded on VTR with CCD camera. The tree length of X, Y axis direction and aging area(treeing area) are calculated with image measurement. As a result of this study, water tree is observed by non-destructive method. Electrical tree is initiated from needle electrode tip only but water tree is initiated from total area of water electrode. Electrical tree owing to water treeing is initiated at low electric field and grown with discontinuously. Namely, water tree is shown up a different characteristics of tree growth.

• Research in Community and Public Health Nursing
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• v.16 no.1
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• pp.49-58
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• 2005

Purpose: The purpose of This pre-post quasi-experimental study was designed to analyze the effects of school based smoking prevention education on knowledge and attitude toward smoking of middle school students. Methods: Data were collected by questionnaires from 320 students of the control group and 244 students of the experimental group in Korea, from June 2 to July 16, 2003. The reliabilities of instruments were adequate (Cronbach's alpha=.75-.92). Data were analyzed by t-test, $x^2-test$ and ANCOVA using SAS V8 program. Results: The results were as follows; 1. The ANCOVA models of the knowledge and attitude toward smoking were very significant to explain about education effects. 2. After the smoking prevention education, the smoking knowledge and attitude of the experimental group was significantly improved, whereas those of control group didn't change significantly. Conclusion: Smoking prevention education for middle school students increased their level of smoking knowledge and attitude. Therefore, it is necessary to give and develop a more effective program which is suitable to the subjects's needs and grades. Furthermore more various teaching methods such as VTR. lectures, role play and long term education program are need to be developed.

• Journal of Power Electronics
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• v.18 no.1
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• pp.81-91
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• 2018

This paper proposes a double line voltage synthesis (DLVS) strategy for three-to-five phase direct matrix converters. In the proposed strategy, the input and expected output voltages are divided into 6 segments and 10 segments, respectively. In addition, in order to obtain the maximum voltage transfer ratio (VTR), the input line voltages and "source key" should be selected reasonably according to different combinations of input and output segments. Then, the corresponding duty ratios are calculated to determine the switch sequences in different segment combinations. The output voltages and currents are still sinusoidal and symmetrical with little lower order harmonics under unbalanced or distorted input voltages by using this strategy. In addition, the common mode voltage (CMV) can be suppressed by rearranging some of the switching states. This strategy is analyzed and studied by a simulation model established in MATLAB/Simulink and an experimental platform, which is controlled by a DSP and FPGA. Simulation and experimental results verify the feasibility and validity of the proposed DLVS strategy.

• Korean Journal of Human Ecology
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• v.19 no.2
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• pp.417-428
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• 2010

The purpose of this study was to analyze differences of the indoor environment and student's fatigue response according to ventilation in university lecture hall. The experiments consisted of measuring the indoor environmental parameters and a survey of student's responses. The experiments were in the lecture hall that the actual lecture was conducted in on the $25^{th}$ of May 2009 (not opening windows and door- A) and the $1^{st}$ of June 2009 (opening windows and door- B). The experimental variable was ventilation by opening the windows and door, and the controlled conditions were indoor temperature by air conditioner, volume of the microphone and VTR, lighting conditions and teaching method. The results are as follows: 1) The indoor temperature was maintained in controlling A, B but the $CO_2$ and relative humidity of A (average 3579ppm, 62.6%) was higher than B (average 1697ppm, 48.1%). 2) There were differences in the student's subjective responses and student's fatigue responses between A and B. 3) Therefore, it was found that ventilation by opening the windows and door was a valid way to improve the relative humidity and to reduce $CO_2$ in the lecture hall.

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.9
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• pp.1288-1295
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• 2009

The study was conducted to investigate the effects of different levels of xylanase on performance, blood parameters, intestinal morphology, microflora and digestive enzyme activities of broilers. The wheat-based diets were supplemented with 0, 500, 1,000, 5,000 U/kg xylanase. Xylanase supplementation significantly (p<0.05) improved the feed:gain ratio of broilers from 1 to 21 d and 1 to 42 d. Supplementing 500 U/kg and 1,000 U/kg xylanase improved (p<0.05) the villus height and the ratio of villus height to crypt depth in the small intestine. Excess supplementation of xylanase (5,000 U/kg) increased the villus height in the ileum (p<0.01) and the ratio of villus height to crypt depth in the duodenum and ileum (p<0.05). The microflora in the ileum and caecum, digestive enzyme activities in the small intestine and the concentrations of serum glucose, uric acid, insulin and IGF-I were not affected by the supplementation of xylanase. Excess level of xylanase (5,000 U/kg) had a tendency to induce the multiplication of E. coli and total aerobes. The results suggested that supplementing 500 U/kg and 1,000 U/kg xylanase was beneficial for broilers and excess xylanase supplementation resulted in no further improvement or negative effects.

• Journal of Korean Academy of Nursing
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• v.30 no.6
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• pp.1556-1568
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• 2000

The aims of this study were to identify the effects on sexual role identity and sexual attitude of the A-V programed sexual education on Oct. 1. 1997 through Sep. 30, 2000. The program was focused on the formation of the desirable sexual activity, attitude and androgyny sexual role identity of the Korean adolescents, and that was the 25 minute VTR media "Our sexuality is healthful". This study was non equivalent post-test only quasi-experimental design, and the subjects were 530 middle school boys in Busan, Korea. After the manipulation, the change of sexual role identity and sexual attitude was analysed. Outcome measures were middle school boys′ sexual role identity toward KSRI on a seven-point Likert scale and sexual attitudes toward SAS on a five-point Likert scale. The data was analysed by SPSS WIN. The results were summarized as follows : 1) The experimental group who was exposed to the A-V media produced by the author showed the higher score of androgyny sexual role identity than the control group who didn′t watch the A-V program. 2) The experimental group showed the higher rate of the androgyny than the control group, On the other hand, their rate of the masculinity turned out to be lower than the latter group. 3) The experimental group didn′t show the difference of SAS score from the control group .In conclusion, "Our sexuality is Healthful" A-V program for sexual education brought about the significant change of sexual role identity of the middle school boys, but didn′t affect their attitude toward sexual activity.

• Journal of the Korean Society of Food Culture
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• v.8 no.1
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• pp.55-62
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• 1993

These studies were conducted to: a) investigate work patterns and productivity indices, b) rate performance levels of employees and c) determine the suggested levels of personnel and labor hours for the effective labor control in school foodservice. Eighteen elementary school foodservices in Seoul were selected in order to analyze work patterns by the work sampling methodology. Allowance time and performance rating by VTR observation was done to determine the standardized labor hours. The results were as follows. The average percentage of each work function of the total work functions such as direct work function, indirect work function and delay were 65.57%, 8.12%, 26.31% respectively. The productivity index is 0.92 min/meal. The average working and delay hours per week of the foodservice director, foodservice employees and supply person were 33.64 hours, 23.25 hours, 38.52 hours respectively. The percentage of delay hours of total labor hours for foodservice employees and supply person were 42.27% and 24.0%. The standardized work hours and the appropriate levels of foodservice employees of 17 elementary school foodservices were examined: The average rating of the foodservice employees work was 1.19 and British Insulated Calendarer Cables (BICC) allowance rate was 19.40% on the average. The total work hours of foodservice employees were 172.64 hours per week and levels of personnel were 4.53 persons. BICC allowance rate was applied: The standardized work hours per week was 180.95 hours and appropriate levels of personnel were 4.11 persons based on legal 44 working hours.

• Journal of Nutrition and Health
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• v.31 no.4
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• pp.787-798
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• 1998

This study is an analysis on how current elementary teachers think about nutrition education, how they are teaching it, and problems that have occurred. The main purpose of this analysis was to deal with future problems in nutrition education by analyzing the present situation . The survey was done on 544 currently working elementary school teachers. from the 9 education departments within Seoul, 2 schools were chosen from each department by stratified random sampling. The survey used a questionnaire that was passed out personally to teachers from September 1, 1997 to the 19th. The 544 usable questionnaires were analyzed by using the teachers had nutrition education training and the average score of nutrition knowledge was 13.30 $\pm$2.73 out of 20. Nutrition education was being taught as apart of other subjects in 87.9% of the schools, and mainly by lecture. Audio visuals aids were used by 53.7% of the teachers and the most common was the VTR. Nutrition education was taught as a part of physical education and 41.5% were using teacher guides to help them. 91.9% of the teachers supported the idea of nutrition education in elementary schools. Nutrition education was supported by 80. 0% of teachers to begin when children are in kindergarten, proving that early nutrition education is supported. The analysis showed that nutrition education should be taught by parents(29.4%) , teachers(29.2%), and nutritionists(25.9%) relating that family , education, and school lunch programs should tie in with each other. 96.7% of the teachers responded that they would teach nutrition education. However, 41.0% disagreed with having a separate course for nutrition education . Proper eating habits, nutrition and its diseases, and growth with nutrition were the main categories within nutrition education and the most effect method was thought to have audio visuals, guides for teachers , and to link the subject matter with school lunch programs. The teachers main responses to problems with children were that they are too much instant food, did not eat in a variety , and had no manners in eating. Ironically, the believed that malnutrition, fainting and growth stunt were not important nutrition problems.

• Journal of Technologic Dentistry
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• v.24 no.1
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• pp.83-93
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• 2002

This study was performed to evaluate the importance of parents, knowledge, cognition and behaviour about dental health care on the development of dental caries in preschoolers. Subjects were comprised of 170 preschoolers collected from three preschoolers placed in Pusan and Kimhae area and study period were 6 months from January, 2000. Examination on the preschoolers' dental health and questionnarie survey on parents' knowledge, cognition and behaviour about dental health care were conducted. Collected data were analyzed by chi-square test and t-test using SAS program. Dental caries was so prevalent as the rate of 73.5%. And, the rate was different by the area(p=0.001), and increased with preschooler's age(P=0.004). The parents gain the knowledge about dental health care mainly from dentist or dental hygienist(32.9%), newspaper, magazine booklets(26.5%), TV and VTR tape(20.0%), etc, but rarely from school health education(4.7%). Caries prevalence was significantly lower in case of regular brushing than that of insufficient brushing(p=0.002) and in case of consistently informing brushing time to their children(p=0.014). This results showed that the dental health care for preschoolers is insufficient and the most important factor for caries prevention is regular brushing. And it seemed that the parent's concern and knowledge play an important role for the prevention of preschooler's dental caries. Dental health education would be focused on the parents, especially for the practice of preventive behavior by preschoolers themselves.

• Journal of Korean Society for Geospatial Information Science
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• v.14 no.1 s.35
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• pp.57-63
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• 2006

The purpose of this study is to correct data on 3 intersection ranging from Kwangchun INT. to Nongsung INT. by the means of VTR recording and site survey and to measure the responsiveness of performance index by diversifying the platoon dispersion factor in signal progression simulation. The results are as follows : 1. The value of platoon dispersion factor was 0.28-0.33. The value in up stream is lower than that of in down stream even on the same intersection. 2. The platoon index showed big changes, though performance index didn't according to platoon dispersion factor. Therefore the value of platoon dispersion factor which is inner variable in T7F can be fixed for 0.34. 3. There was only little divergence in performance index changes according to platoon dispersion factor in designing the progression or T7F model.