• Tribology and Lubricants
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• 제36권2호
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• pp.105-115
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• 2020

This paper presents a numerical study on the rotordynamic analysis of a dual-spool turbofan engine in the context of blade defect events. The blades of an axial-type aeroengine are typically well aligned during the compressor and turbine stages. However, they are sometimes exposed to damage, partially or entirely, for several operational reasons, such as cracks due to foreign objects, burns from the combustion gas, and corrosion due to oxygen in the air. Herein, we designed a dual-spool rotor using the commercial 3D modeling software CATIA to simulate blade defects in the turbofan engine. We utilized the rotordynamic parameters to create two finite element Euler-Bernoulli beam models connected by means of an inter-rotor bearing. We then applied the unbalanced forces induced by the mass eccentricities of the blades to the following selected scenarios: 1) fully balanced, 2) crack in the low-pressure compressor (LPC) and high pressure compressor (HPC), 3) burn on the high-pressure turbine (HPT) and low pressure compressor, 4) corrosion of the LPC, and 5) corrosion of the HPC. Additionally, we obtained the transient and steady-state responses of the overall rotor nodes using the Runge-Kutta numerical integration method, and employed model reduction techniques such as component mode synthesis to enhance the computational efficiency of the process. The simulation results indicate that the high-vibration status of the rotor commences beyond 10,000 rpm, which is identified as the first critical speed of the lower speed rotor. Moreover, we monitored the unbalanced stages near the inter-rotor bearing, which prominently influences the overall rotordynamic status, and the corrosion of the HPC to prevent further instability. The high-speed range operation (>13,000 rpm) coupled with HPC/HPT blade defects possibly presents a rotor-case contact problem that can lead to catastrophic failure.

• 대한지역사회영양학회지
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• 제14권1호
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• pp.55-66
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• 2009

This study was aimed to examine nutrition knowledge, dietary attitudes, and eating habits of elementary school students and to examine if their characteristics differ by gender. Subjects were 5th and 6th graders of an elementary school (n = 317) in Seoul, and the survey was done during July 2007. Mean height, weight, BMI of subjects was 148.1 cm. 41.7 kg, 19.0, and 14.3% of subjects were categorized as the overweight/obese group. Anthropometric data were not significantly different by gender. Mean score of nutrition knowledge was 14.9 out of 20 showing moderate knowledge levels, and girls scored higher on nutrition knowledge than boys (p < 0.05). Subjects showed knowledge deficit in areas such as nutrients, food groups and specific weight control information. The percentages of correct answers regarding meals for brain function were significantly higher in girls than in boys (p < 0.05). They got nutrition information mainly from mass media and family/relatives. The mean score of dietary attitudes was 41.2 (possible score: 10-50) indicating somewhat positive attitudes, and the score of eating behaviors was 34.8 (possible score: 15-45). Subjects showed problems in eating habits such as having unbalanced diets and snack foods. 82.6% of subjects had unbalanced meals, and these percentages were higher in girls (87.2%) than in boys (78.1%, p < 0.05). Vegetables and fish/shellfish were the most disliked foods. Specific eating behaviors, such as eating slowly, eating grains and having processed foods less frequently, were better in girls than in boys (p < 0.05). Results also showed that majority of subjects need to improve specific behaviors including having diverse foods, eating meals slowly, having meals at regular times, having adequate foods in each food groups, and eating sweets or salty foods less frequently. Only 52.7% of subjects perceived their body images as normal, and 56.4% had experience of weight control. Reasons for weight control were different by gender (p < 0.05). Based on these findings, nutrition education for school children should focus on modifying eating habits or eating behaviors, by suggesting practically applicable methods and providing nutrition information that is interesting and suitable to school-aged children.

• Journal of Nutrition and Health
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• 제37권3호
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• pp.193-201
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• 2004

The objective was to evaluate the factors influencing on the growth of children aged 3 - 6 years by mini dietary assessment and anthropometric indices in 556 children and by analyzing mineral contents of hair from 273 children by inductively coupled plasma mass spectrometry (ICP-MS). The mean concentration of zinc (Zn) in hair was 68.9 $\pm$ 31.1 ppm and the zinc level of 91 ％ children was less than 60％ of the reference value of 180 ppm. The mean content of lead (Pb) in hair was 1.76 $\pm$ 1.20 ppm, but only 67％ of 273 children was within the reference value of 2 ppm and the lead level of 33％ of children was 2 - 4 times higher than the reference value. The level of Zn was negatively correlated with Pb content (r = -0.305, p 〈 0.01). Hair Zn content, regardless of age, was significantly positively correlated with height (r = 0.214) and body weight (r = 0.159). The height of 95.3％ children was belonged to the normal range of 90 - 109.9％ of standard value and the body weight of 49.8％ children was in the range of 90 - 109.9％ of standard value. However, 8.1 ％ children was overweighted (110 - 119.9％ of standard) and 9.4％ children was obese (120 - 149.9％ of standard) and 0.9％ children was severe obese (〉 150％) which resulted in total 10.3％ obese. Contrary to our expectation, 32.8％ children was underweight (70 - 89.9％ of standard) and 36％ of the underweight children showed the low content of zinc (10 - 49 ppm) in hair. There was no significant correlation between dietary intake of Zn and hair Zn content. Hair Zn content was low even though children consumed greater than 75％ of their requirement for zinc. Regardless of dietary intake of Zn, hair Zn level was rather negatively correlated to the content of Pb in hair. 38.8％ children had an unbalanced diet which resulted in lower intake of calorie, Ca, Zn, vitamin B$_2$ compared with those consuming variety of foods. Therefore, it would be needed that new approach for nutrition education to improve eating habit having the unbalanced diet in preschool children. It might be also suggested to develop new food products to complement the nutrients of Zn, Ca, Fe as snacks or dietary supplement for Korean preschool children.

• Journal of Community Nutrition
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• 제1권1호
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• pp.25-32
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• 1999

In this study, focus group interviews were used to investigate female university students' eating behavior, factors related to eating behavior, information sources for nutrition, and formats for nutrition education. Thirty-six students participated in one of five focus groups during December 1998 in Seoul. Focus group discussions were video, audio-taped, transcribed and analyzed by major themes. Results showed that subjects have undesirable eating behaviors, such s eating irregular meals and skipping meals. These behaviors are caused by a lack of time, habit, or for the purpose of losing weight. The students tended to have unbalanced diets and frequently ate out. They had a large amount for dinner and frequently snaked when stressed or had an empty stomach. Most of them were interested in weight control and had attempted to lose weight, but they did not participate in regular exercise. The most frequently used source for nutrition information was the mass media, but much nutrition information was based on what they learned from home economics class during middle to high school. They received more support from mothers, elder sisters, and friends for eating behaviors, such s lowering caloric intake and losing weight. In nutrition education, they wanted to learns behaviorla skills to adopt healthy behaviors, including meal planning, applying scientific weight control methods, exercise that fit into their lives, and stress management. They also mentioned that nutrition screening and assessment should be a part of nutrition education programs. As a method for nutrition education, subjects preferred an individualized approach to group education. These results provide the qualitative information for developing nutrition education programs which will be implemented for Korean University students.

• Journal of Microbiology and Biotechnology
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• 제25권12호
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• pp.2090-2099
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• 2015

Recently, the cardiovascular disease has been widely problematic in humans probably due to fibrin formation via the unbalanced Western style diet. Although direct (human plasmin) and indirect methods (plasminogen activators) have been available, bacterial enzyme methods have been studied because of their cheap and mass production. To detect a novel bacterial fibrinolytic enzyme, 111 bacterial strains with fibrinolytic activity were selected from kimchi. Among them, 14 strains were selected because of their stronger activity than 0.02 U of plasmin. Their 16S rRNA sequence analysis revealed that they belong to Bacillus, Leuconostoc, Propionibacterium, Weissella, Staphylococcus, and Bifidobacterium. The strain B. subtilis ZA400, with the highest fibrinolytic activity, was selected and the gene encoding fibrinolytic enzyme (bsfA) was cloned and expressed in the E. coli overexpression system. The purified enzyme was analyzed with SDS-PAGE, western blot, and MALDI-TOF analyses, showing to be 28.4 kDa. Subsequently, the BsfA was characterized to be stable under various stress conditions such as temperature (4-40oC), metal ions (Mn²⁺, Ca²⁺, K²⁺, and Mg²⁺), and inhibitors (EDTA and SDS), suggesting that BsfA could be a good candidate for development of a novel fibrinolytic enzyme for thrombosis treatment and may even be useful as a new bacterial starter for manufacturing functional fermented foods.

• 한국지진공학회논문집
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• 제3권1호
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• pp.103-112
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• 1999

본 연구는 두 지점간의 진동수 응답함수를 이용하여 시간 및 진동수 영역에서의 원심펌프(20Hp. 50Hp) 가진력을 추정하기 위한 것이다. 진동수 응답함수는 실수부와 허수부에 대한 신호정보를 가지고 있으며 응답함수 역시 실수부와 허수부에 대한 신호정보를 가지고 있다 따라서 이들 진동수 응답함수 및 응답함숴의 복소수 계산으로부터 가진력을 실험적으로 구하였으며 이론적인 방법에 의하여 구한 가진력과 실험적으로 구한 값을 비교함으로서 펌프에 의한 주진동수 성분의 크기는 펌프 및 모터중량의 10-25% 정도가 됨을 제시하였다. 가진력 산정을 위한 시간영역에서의 불평형질량의 크기는 펌프 및 모터중량의 약 30-60%임을 알수 있었다 한편 펌프회전에 의한 진동은 주진동수 이외에도 주진동수의 2-3배의 크기를 갖는 성분이 있음을 알 수 있었으며 대상 콘크리트 슬래브의 고유진동수와의 가진진도수비를 달리함에 따라 정확한 진동전달률을 조절하는데 활용할 수 있다.

• 한국식품영양학회지
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• 제24권2호
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• pp.145-152
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• 2011

This study was conducted to investigate the meal quality and dietary behaviors of low-income family children by qualitative method. The subjects were 12 children(2 boys and 10 girls) aged 7 to 11, enrolled in an after-school care center in Kimpo, Gyeonggi province. Most of their mothers had jobs(83.3%) and 75% were the beneficiaries of a government assistance program. When compared using body mass index(BMI) percentile, 16.7% of the subjects were classified as being overweight. The food intake patterns and meal qualities were evaluated from dietary records for three non-consecutive days. The mean dietary diversity score(DDS) was 3.8, suggesting at least one food group was deficit. Only 8.3% of the records indicated a satisfactory intake of all five food groups, and fruit was the most deficit food group(58.3%). Also, the proportion of balanced of meals was low, especially breakfast(36%), in that main dish(the source of protein) was not included. The children had problematic eating behaviors, such as an unbalanced diet, eating meals in a hurry, skipping breakfast, and irregular meal times. They answered that they liked to eat simple meals and convenient foods. In conclusion, nutrition education should incorporate strategies to reach families and help with meal planning and management, as well as modifying the eating behaviors of children, in order to improve nutritional status.

• 동아시아식생활학회지
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• 제14권2호
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• pp.113-122
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• 2004

This study was conducted to examine the correlation among growth development, bone mineral density, and nutrient intakes in preschool children. A total of 62 preschool children measured the anthropometric characteristics and the bone mineral density of carpus using DEXA. The questionnaires categorized to determine health status, life style, dietary behaviors, and dietary intakes were filled out by children's mothers. The average ages of the study subjects were 62.4 months in boys and 62.1 months in girls. The birth height and weight of the subjects were 50.9 cm and 3.4 kg in boys and 50.3 cm and 3.3 kg in girls, respectively. The average height, weight, % body fat, and obesity index were 111.7 cm, 19.6 kg, 15.0%, -2.1% in boys and 109.4 cm, 18.7 kg, 17.5%, 0.2% in girls, respectively. The bone mineral density in carpus was 0.25 g/cm$^2$ in boys and 0.24 g/cm$^2$. In girls. Proportions of children having regular meals were 69.0%, 94.7%, and 69.0% for breakfast, lunch, and dinner, respectively. The major reasons for irregular meal were poor appetite and lack of time for breakfast and snacks for dinner. Most of the children(52.6%) had breakfast with the whole family together, and all the children had lunch and dinner with a part of the family. Most of the children answered they had snack more than once a day, and 64.3% had an unbalanced diet. The intakes of energy, calcium, iron, zinc, vitamin A, vitamin B$_1$, niacin, and vitamin C did not meet the Korean RDAs. Average bone mineral density in carpus was positively correlated to the body weight, the total body water, the lean body mass, and the obesity index, respectively(p＜0.01, p＜0.01, p＜0.01 and p＜0.01). The body weight, the total body water, and the lean body mass showed the significant negative correlations with the animal iron intake(p＜0.05, p＜0.01 and p＜0.01). The bone mineral density in the distal carpus was negatively correlated to the animal protein intake and the animal iron intake(p＜0.05 and p＜0.05). And the bone mineral density in the ultradis carpus and the average bone mineral density in the carpus were positively correlated to the plant calcium intake(p＜0.05 and p＜0.05). Therefore, more systematic studies to investigate the roles of protein, iron, and calcium in growth development of preschool children were required.

• 대한간호학회지
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• 제3권3호
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• pp.36-49
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• 1973

This study was carried out for the objectives to collect the basic informations on the health behaviors of the elementary school children in an urban area in Korea. Seven hundred students were drawn to fill in the designed questionnaire which carries variety of Questions on health re-lated behaviors in general, eating habits, disease history, mental health, and sex education. Questionnaire were filled in by their parents. Major findings are as follows: ① 55.7% had habits of washing the hands before eating whereas 59.8% trashing their hands after toilet. The others had no idea of washing hands before eating and after toilet. ② 26,5% had habits of brushing the teeth twice a day 54.7% only once in the morning, and 2.6% once only in the evening. Thus, the idea of prevention from decayed teeth seems to be lacking among the school children. ③ Bathing habits were also inquired to get 40.3% of bathing more than once a week, 43.1% once every two weeks, and the rest of 16.6% once every one to three months. ④ 41.7% keep the regular bedding time whereas 58.3% irregular. Physical exercises were con-ducted by 76.6% on the ground while 23.5% did not practice any physical exercises at all. Of those physical exercises, rope skipping occupied 37.5%, and the other 66.9% consisted of 14 different kinds of individual type physical exercises such as gymnastic exercise. The main reasons for not enjoying exercises were different by sex; boys largely complained the inadequacy and lack of gymnastic facilities and girls felt in short of friends who could join the exercises. ⑤ 31.9% of the school children had been taking not much of food while 28.3% had unbalanced diets. Of these unbalanced diets, meat occupied 33.2% to be the priority to have an order of the following items such as vegetables, bread or noodle, and fishes as next to each. For eating habits, 88.5% take simple snack such as bread (38.4%, cookies, fruits, and candies in order. 25.8% of the children were provided such snacks or their parents regularly. Breakfast was sufficiently taken by 45.0% whereas 8.4% had never sufficiently. As to the lunch, 63.6% had sufficiently while 16.8% insufficiently. 70.6% take breakfast with all family members together and 30.4% separately. Correlation of sufficient taking of breakfast and eating together of tile family member's seems to be significant when we compare 72.5% of sufficient takers who enjoy breakfast together with the family members with 55.6% of insufficient takers who enjoy it with the family. This finding allows the investigator to point out the importance of table circumstances for children's eating. ⑥ The most common disease was catching a cold (38.8%), and the second was stomach trouble to be followed by the frequency of car sickness, headache, and skin infection. Doctors are consulted only by 23.9% when they are sick whereas 59.7% resorted to the drug stores. The lower the educational attainment of the parents, the lower the rate of visiting clinics. ⑦ 36.7% of their parents pointed out the problems of personality guidance as the most difficult thing at home 71.3% of their parents worried about and unsatisfied with their children's personality traits. Of these complains of the parents, impatience stood at the top to be tabulated at 24.1%, and 21.1% indicated narrow-mindedness. In line with this primary socialization at home, the most crucial problem seems to be related with the lack or recognition of the parents'own role when we find only 43.1% of the parents understood the importance of their own role for the home education of children; the latter group attributed tile responsibility of personality formation to the children themselves. ⑧ As to the sex educational aspects, 30.9% of children have ever asked about the physiology of reproduction or sexual matters to their parents, of those parents only 17.0% could give the constructive responses to the inquiries of the children. In companies on with these data, 25.6% recognized their own role in sex education for their own children while the large segments of the parents (51.1%) attributed the responsibility of sex education to tile low level of 38.3% who recognized the importance of sex education in the school curriculum and 25.1% of the parents insisted to wait until they get to know naturally about sex. 38.1% of the parents said they had some knowledge on sex from books while 16.9% through mass media. The next groups had common senses of sex from their own parents, school friends and other sources.

• 한국식품영양과학회지
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• 제43권6호
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• pp.926-933
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• 2014

본 연구는 청소년을 대상으로 BMI에 따라 채소류의 섭취상태를 조사함으로써 체형에 따른 적절한 채소 섭취지도와 바람직한 식생활 및 식습관 형성에 필요한 기초자료를 제시하고자 하였다. 따라서 충남 부여군에 거주하는 중 고등학교 청소년 400명을 대상으로 BMI에 따라 저체중군, 건강체중군, 과체중 이상 군으로 분류하여 식습관, 채소류의 1일 섭취수준, 채소류에 대한 인식, 채소류 관련 식습관을 비교 분석하였다. 조사대상자의 가족 수는 4명(49.0%)이 가장 많았고, 아버지 학력과 어머니 학력은 '고등학교 졸업'이 각각 39.0%, 59.0%로 가장 많았으며, 월평균소득은 '300~400만원(32.3)%'이 가장 많았다. 아침식사를 거르는 이유는 '시간이 부족해서(44.3%)'가 가장 많았으며, 편식하는 음식의 종류는 저체중과 과체중의 경우 '곡류'라는 응답이 가장 높게 나타난 반면, 건강체중의 경우에는 '채소류'라는 응답이 가장 높아 유의한 차이를 보였다(P<0.001). 채소류의 1회 섭취량을 고려한 1일 섭취횟수는 저체중군 3.3회, 건강체중군 3.8회, 과체중군 3.8회로 체형군별 유의한 차이가 없었다. 그러나 점심식사를 통한 채소류의 섭취횟수는 저체중군이 1회로 건강체중군 1.3회와 과체중군 1.4회보다 유의하게 낮았다(P<0.05). 채소류에 대한 인식도 평가에서 채소류는 '먹으면 피부가 예뻐진다'(P<0.01)와 '조리방법에 따라 먹을 때도 있고 먹지 않을 때도 있다'(P<0.05)라는 인식이 저체중군에서 유의하게 높았다. 채소류 관련 식습관 평가에서 저체중군의 채소류 기호도는 건강체중과 과체중군에 비해 낮았으며, 채소가 좋은 이유는 '맛이 있어서', 채소가 싫은 이유는 '그냥'이, 채소의 섭취량은 '급식과 집에서 먹는 양이 비슷하다'가, 싫어하는 채소 색은 '흰색', 싫어하는 채소 조리법은 '삶아서 무침', 채소의 싫어하는 느낌은 '쌉쌀하다', 선호하는 김치는 '나박김치'라는 응답이 가장 많았다. 이상의 결과를 종합하면, 본 조사 청소년의 채소류 섭취는 전반적으로 낮았으며, 특히 건강체중군은 채소류에 대한 편식이 높았고 저체중군은 점심식사를 통한 채소류의 섭취횟수와 채소류에 대한 기호가 유의하게 낮았다. 앞으로 청소년의 체형과 채소류 섭취와의 관계를 보다 정확하게 규명하기 위한 연구와 함께 본 연구 결과를 고려한 적절한 채소류 섭취지도가 지속적으로 이루어져야 할 것이다.