• 한국추진공학회지
• /
• 제26권1호
• /
• pp.77-87
• /
• 2022

한국항공우주연구원 스크램제트 엔진 시험설비를 활용한 스크램제트 엔진 흡입구 지상 시험을 수행하기 위하여 일반적으로 진행하는 시험 가능 여부 확인 절차를 소개하였다. 스크램제트 흡입구 시험을 수행하기 위하여 새롭게 제작된 마하 5 노즐의 설계 과정을 정리하였으며, 노즐의 코어 유동 분포를 확인하기 위한 장치를 설명하고 코어 유동 시험 분석 결과를 기록하였다. 일련의 시험 결과를 통하여 흡입구가 신규 마하 5 노즐 코어에 위치하는 것을 확인하였다.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2001년도 추계학술대회논문집B
• /
• pp.934-939
• /
• 2001

In computational study of the flow in piston engines and the flow through moving valves, the use of moving vertices is essential for modelling flows with moving boundaries. The positions of cell vertices in such cases must be allowed to vary with time. To simulate 3-dimensional port-valve and piston-cylinder of HIMSEN 6H21/32 engine, a commercially available code, STAR-CD, was used. Changes in mesh geometry was specified by PROSTAR commands.(i.e. the Change Grid operation in the EVENTS command module.) Control of the intake flow is expected to play an important role as designers seek to obtain better fuel spray characteristics, fuel mixing and mixture preparation, combustion performance, and emissions reductions to meet national standards. As a result of analysis, velocity fields indicate the presence of a structured flow comprised of one pair of counter-rotating vortices under the intake valve during the early induction process. These flow structures remain visible for most of the intake process. As the piston moves towards BDC, these vortices develops into a larger tumbling motion that dominates the flow structure.

• 동아시아식생활학회지
• /
• 제15권1호
• /
• pp.1-10
• /
• 2005

Dietary behavior, body mass index(BMI) and nutrient intake status of 185 boys and 205 girls in 3rd grade middle school students in Daegu area were analyzed. Boys were 168.6cm tall and weighed 61.3kg on the average and girls 158.5cm and 54.4kg, respectively. From their BMIs, 17.9% were classified as the underweight, 54.2% as the average, 14.7% as the overweight and 13.2% as the obesity. The average energy intake per day was 2222.6 kcal for boys, 1796.2 kcal for girls which were 83.3% and 86.6% of the RDA, respectively. Composition rate of carbohydrate, protein, fat in relation to energy intake was 62.4 : 16.5 : 21.1 for boys and 58.8 : 16.0 : 25.2 for girls. Protein was taken low and carbohydrate and fat were high in this study. Particularly, fat intake rate of girls was high. Calcium, iron, vitamin A, and vitamin B2 did not meet the RDA and especially calcium was taken 63.9% for boys and 54.01 % for girls. Most of the students have tendency to eat irregularly and to overeat. For the nutrients intake, calories and calcium intake were lower than the RDA regardless of gender and iron intake was not enough for girls only. In relation to BMI, obesity group students were taking lower calories and proteins than the normal students were. No consistent trend was shown for boys about nutrient intake in relation to eating speed. Students had a correct perception of their body image which was similar to that of their mothers. Nutrient average intake is under the average and the percentile under 70% of RDA was high contrary to the fact that nutrient intake like calcium and iron was exceedingly important particularly in the growth process. Therefore, nutritional education for the proper intake of nutrients was required for the students in Daegu area. Especially, education has to be focused on the balanced diet and correct food choices for the proper dietary behaviors.

• Journal of Nutrition and Health
• /
• 제43권6호
• /
• pp.597-606
• /
• 2010

본 연구에서는 채소와 과일 섭취 증진을 위한 영양교육이 행동변화단계의 진전에 따라 사회심리적요인에 변화를 초래하는지 파악하고자 초등학생을 대상으로 영양교육을 실시한 후 행동전단계를 두 단계로 나누어 이 두 단계 아동들의 채소와 과일 섭취의 장점과 단점에 대한 인지, 인지적 행위적 변화과정, 자아효능감의 수준 변화를 조사하였다. 충남 연기군의 한 초등학교 5학년 아동 71명에 대한 설문 조사에 의해 행동전단계 (고려전, 고려, 준비)로 분류된 47명을 대상으로 2007년 11월 19일부터 12월 24일까지 6주 동안 채소와 과일섭취 영양교육을 실시하고 교육전과 후에 사회심리적요인의 수준을 설문지법에 의해 조사하였다. 1) 영양교육 후 채소섭취의 장점에 대한 인지도 점수는 고려전단계나 고려 및 준비단계에 속한 대상자 모두에서 증가하였고, 단점에 대한 인지도 점수는 두 단계 모두에서 감소하였다. 그러나 과일섭취에 있어서는 장점에 대한 인지도 점수에서는 고려전단계와 고려 및 준비단계 모두에서 교육 후 변화가 없었으나, 단점에 대한 인지도 점수는 고려전 단계에 속한 대상자에서만 유의적인 감소가 나타났다 (p < 0.01). 채소섭취에 대한 장점과 단점에 대한 인지 개선 영양교육은 두 단계 모두에서 효과적이었다. 2) 영양교육 후 채소섭취의 인지적 변화과정에서는 고려전단계의 대상자에서 의식향상 (p < 0.001)점수가 증가되었고, 고려 및 준비단계에 속한 대상자에서는 걱정해소 (p < 0.01), 자기재진단 (p < 0.05), 환경재평가 (p < 0.01), 사회규범변화(p < 0.05) 등 여러 변수의 점수가 증가하였다. 과일섭취의 인지적 변화과정에서는 고려전단계에 있는 대상자에서 환경재평가 (p < 0.01)점수의 증가를 나타내었고, 고려 및 준비단계에서는 변화를 보인 변수가 없었다. 채소와 과일섭취의 행위적 변화과정에서는 모두 변화가 없었다. 3) 영양교육 후 채소섭취에 관한 자아효능감은 고려전단계에 있는 대상자에서 '채소를 보이는 곳에 둔다' (p < 0.01)와 '혼자 채소를 먹을 때 권장섭취 횟수만큼 먹을 수 있다' (p < 0.01). '채소 먹을 시간을 낼 수 있다' (p < 0.05)에서 증가를 나타내었다. 고려 및 준비단계에서는 고려전단계에서 나타난 '혼자 채소를 먹을 때 권장섭취 횟수만큼 먹을 수 있다' (p < 0.01)와 '채소 먹을 시간을 낼 수 있다' (p < 0.01)의 항목을 포함하여 '다양한 종류의 채소를 살 수 있다' (p < 0.01)에서 교육 후에 자아효능감이 높아졌다. 즉 채소섭취의 행동변화단계가 높아질수록 자아효능감의 수준이 성숙됨을 보였다. 과일섭취에 대해서는 영양교육 후 고려전단계에 속한 대상자에서 '과일을 보이는 곳에 둔다'의 자아효능감의 점수가 증가되었다 (p < 0.05). 이상의 연구결과에서 영양교육 후 행동전단계에 있는 아동들의 행동변화단계의 진전이 일어났고, 고려전단계와 고려 및 준비단계에서 모두 사회심리적요인의 수준이 높아졌으나 두 단계 간에는 교육효과의 유의적인 차이가 없었다. 과일에 비해 채소섭취와 관련된 사회심리적요인에서 교육 효과가 더 크게 나타났으며, 사회심리적요인들 중에서 판단 균형의 단점에 대한 인지도, 인지적 변화과정, 자아효능감이 영양교육의 평가지표로 사용될 수 있는 가능성을 보였다.

• 대한지역사회영양학회지
• /
• 제8권2호
• /
• pp.160-170
• /
• 2003

Pregnant women in South Korea are a highly risk group fur iron deficiency anemia. Previous studies indicated that the 24-hour recall method was insensitive in distinguishing iron deficiency anemic women from normal women. This method is also impractical to when used at community health centers where no public health dietitians are employed. The objective of this study was to develop a convenient tool to evaluate the usual iron (Fe) intake of pregnant women. The study participants were 115 pregnant women (age 23 to 37 years) at gestational stage of 13 to 24 weeks. Anemic subjects were classified on the basis of their serum ferritin < 12.0 ${\mu}$g/L and hemoglobin < 12.0 g/dL levels. Food frequency questionnaires with 46, 29, and 15 commonly consumed food items were used to measure the usual intake of iron of the subjects. Hemoglobin and serum ferritin were measured from fasting blood samples. Nutrients intake was assessed on three consecutive days using the 24-hour recall method and the food record method. The iron index score calculated using the food frequency method showed a significantly positive correlation with iron intake for the three days dietary intake. The iron index showed a significantly difference (p < 0.05) between the normal and anemic groups. However, there was no significant difference in the iron intake between the anemic and the normal women as measured by the 24-hour recall and food record method. Our study indicated that the 29-food items questionnaire could be used as a screening tool to identify poor dietary intake of iron. (Korean J Community Nutrition 8(2) : 160170, 2003)

• 한국자동차공학회논문집
• /
• 제10권1호
• /
• pp.51-58
• /
• 2002

A simulation model has been developed to predict the performance of 5-valve gasoline engine by gas exchange process with combustion model. In this study, we simulated the intake flow characteristics and performance of 5-valve engine with entwine speed and we compared the 5-valve engine performance with that of 4-valve engine. As a result. the calculated value was in consistency with the measured value relatively. The performance of 5-valve engine was higher than that of 4-valve engine in high engine speed region.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2011년도 제42회 하계학술대회
• /
• pp.930-931
• /
• 2011

As the upsurge in oil prices and global warming, Energy saving is needed to overall industry. If The head of Intake gate screen is high. The pumping process involves a loss of energy and results in high emissions of greenhouse gases. Therefore, blockages in intake gate should be free. Another advantage of cleaning is stabilizing pumping system. Because vibration and cavitation decreases when loss of head is low.

• Journal of Nutrition and Health
• /
• 제34권1호
• /
• pp.98-111
• /
• 2001

The article demonstrates a method of studying human health and nutrition by applying a multi-disciplinary approach and examines how humans developed and survived by adjusting to their environment. This process involves physiological, cultural and genetic adaptation both independently and interactively. This study postulates that a sound human health may be the result of balance between nutrition and environmental conditions. It is noted that there is a positive correlation between malaria and fava bean intake, and sickle cell anemia and cassava intake. It is also suggested that the difference in disease structure in soybean and non-soybean consumption cultures can be explained by an ecological approach to studying nutrition. This study further suggest that the relationship between nutrition and socio-cultural system. epidmiological study of nutrition and cultural environment nutrition and conceptual characteristics, nutrition and food intake pattern, nutrition and health sociological functions and the physioloical, cultural and genetic adaptation can all be stimulating research subjects to be studied form and ecological point of view. This article also includes the results from a series of ecological studies conducted by the author investigating the relationship between nutritional status of Korean breast-feeding mothers and the composition of the human milk and also the Vitamin D status of Korean and their lifestyle. (Korean J Nutrition 34(1):98-111, 2001)

• Journal of Advanced Marine Engineering and Technology
• /
• 제18권2호
• /
• pp.97-103
• /
• 1994

This paper describes briefly the simulation program for predicting the performance of a high speed turbocharged four cycle diesel engine. The wave phenomena in the intake and exhaust systems are calculated by the characteristic method. The combustion process in the power cycle is represented by the heat release pattern which is given by the Wiebe's function or the pattern based on measured values. Turbocharger matching for the engine is described by utilizing the characteristic maps of both the compressor and turbine, which are obtained from quasi-steady states. A comparison of experimental and calculated results shows a good agreement. Then the influences of the intake system, the period of valve overlap and the characteristics of the turbine are numerically investigated by the simulation.

• Journal of Mechanical Science and Technology
• /
• 제15권1호
• /
• pp.108-116
• /
• 2001

The in-cylinder flow field of gasoline engine comprises unsteady compressible turbulent flows caused by the intake port, combustion chamber geometry. Thus, the quantitative analysis of the in-cylinder flow characteristics plays an important role in the improvement of engine performances and the reduction of exhaust emission. In order to obtain the quantitative analysis of the in-cylinder gas flows for a gasoline engine, the single-frame particle tracking velocimetry was developed, which is designed to measure 2-dimensional gas flow field. In this paper, influences of the swirl and tumble intensifying valves on the in-cylinder flow characteristics under the various intake flow conditions were investigated by using this PTV method. Based on the results of experiment, the generation process of swirl and tumble flow in a cylinder during intake stroke was clarified. Its effect on the tumble ratio at the end of compression stroke was also investigated.