• 제목/요약/키워드: Mean Normal Stress

검색결과 183건 처리시간 0.021초

공간적 상관길이와 유효수직응력의 효과에 따른 거친 단일 균열내의 용질이동특성에 관한 수치적 연구 (A Numerical Study on Characteristics of Solute Transport in a Rough Single Fracture with Spatial Correlation Length and Effect of Effective Normal Stress)

  • 정우창
    • 한국지반환경공학회 논문집
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    • 제10권1호
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    • pp.5-14
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    • 2009
  • 본 연구에서는 유효수직응력의 영향을 받고 있으며, 공간적으로 상관된 간극분포를 포함하고 있는 단일 균열 내에서의 용질이동에 대한 공간적 거동을 수치적으로 분석하였다. 분석결과 단일 균열에서의 용질이동은 간극분포의 공간적 상관정도와 적용된 유효수직응력에 크게 영향을 받는 것으로 나타났다. 공간적 상관길이가 증가함에 따라 용질입자의 평균이동시간은 감소하였으며, 또한 용질이동에 대한 굴곡도와 Peclet 수(유체흐름에 의한 용질의 이송율과 분자확산율과의 관계를 나타내는 무차원 수)가 감소하는 경향을 나타내었다. 이는 공간적 상관길이가 증가할수록 단일 균열 내의 간극분포가 용질입자의 이동에 유리하다는 것을 의미한다. 그러나 유효수직응력이 증가할수록 용질입자의 평균이동시간과 굴곡도는 증가하는 경향을 나타냈으며, Peclet 수는 감소하는 경향을 나타냈다. 이는 유효수직응력이 증가할수록 접촉면의 증가로 인해 한 두 개의 상대적으로 큰 국부유량을 가지는 유로를 따라 이동하기 때문인 것으로 판단된다. 또한 본 연구에서 용질이동에 대한 모의된 결과에 근거하여 공간적 상관길이에 따른 유효수직응력과 용질의 평균이동시간과의 관계를 나타내는 지수형태의 상관식을 제안하였다.

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Effects of cranberry powder on biomarkers of oxidative stress and glucose control in db/db mice

  • Kim, Mi Joung;Chung, Jee-Young;Kim, Jung Hee;Kwak, Ho-Kyung
    • Nutrition Research and Practice
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    • 제7권6호
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    • pp.430-438
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    • 2013
  • Increased oxidative stress in obese diabetes may have causal effects on diabetic complications, including dyslipidemia. Lipopolysccharides (LPS) along with an atherogenic diet have been found to increase oxidative stress and insulin resistance. Cranberry has been recognized as having beneficial effects on diseases related to oxidative stress. Therefore, we employed obese diabetic animals treated with an atherogenic diet and LPS, with the aim of examining the effects of cranberry powder (CP) on diabetic related metabolic conditions, including lipid profiles, serum insulin and glucose, and biomarkers of oxidative stress. Forty C57BL/KsJ-db/db mice were divided into the following five groups: normal diet + saline, atherogenic diet + saline, atherogenic diet + LPS, atherogenic diet + 5% CP + LPS, and atherogenic diet + 10% CP + LPS. Consumption of an atherogenic diet resulted in elevation of serum total cholesterol and atherogenic index (AI) and reduction of high density lipoprotein (HDL)-cholesterol. However, with 10% CP, the increase in mean HDL-cholesterol level was close to that of the group with a normal diet, whereas AI was maintained at a higher level than that of the group with a normal diet. LPS induced elevated serum insulin level was lowered by greater than 60% with CP (P < 0.05), and mean serum glucose level was reduced by approximately 19% with 5% CP (P > 0.05). Mean activity of liver cytosolic glutathione peroxidase was significantly increased by LPS injection, however it was reduced back to the value without LPS when the diet was fortified with 10% CP (P < 0.05). In groups with CP, a reduction in mean levels of serum protein carbonyl tended to occur in a dose dependent manner. Particularly with 10% CP, a reduction of approximately 89% was observed (P > 0.05). Overall results suggest that fortification of the atherogenic diet with CP may have potential health benefits for obese diabetes with high oxidative stress, by modulation of physical conditions, including some biomarkers of oxidative stress.

한국의 젊은 남성에서 족관절 안정성에 대한 부하검사시의 결과 (Results in Stress Test in the Ankle Stability of Young Men in Korea)

  • 이경태;이영구;최병옥
    • 대한족부족관절학회지
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    • 제12권1호
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    • pp.36-40
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    • 2008
  • Purpose: The purpose of this study is to find out the normal results in ankle on varus stress, valgus stress, and anterior draw stress in young men in korea. This would be helpful as the basic data of measuring of ankle instability for operational indication. Materials and Methods: Varus and Valgus stress anteroposterior radiographs and Anterior drawing stress lateral radiographs of 600 normal ankles were reviewed. First, A line parallel was drawn parallel to the articular surface of the distal tibia, and another line was drawn parallel to the articular surface of the talus on anteroposterior radiographs. The interior angle that subtended by these two lines was measured. Second, the reference point is located at the posterior border of the tibia, and the shortest distance from this point to the proximal posterior articular surface of the talus is measured. Results: There were 300 males and 600 ankles. The mean age overall was 21 years (19-22 years) old. The mean length of ankle on anterior draw stress was $5.54{\pm}3.33\;mm$. The mean a interior angle of ankle on varus stress was $0^{\circ}-8.93^{\circ}$, and on valgus stress $0^{\circ}-7.78^{\circ}$. Conclusion: We can consider for operational indication at over the 8.87 mm on anterior draw stress, over the $8.93^{\circ}$ on varus stress, and over the $7.78^{\circ}$ on valgus.

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3대 열량소를 스스로 선택하게 했을 때 흰쥐의 식이 선택성향 및 저전류 Stress가 이에 미치는 영향 (Studies on Self-Selection of 3 macronutrients and the Effect of Electric Stress on Food Selection in Male Rats)

  • 장영애
    • Journal of Nutrition and Health
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    • 제23권7호
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    • pp.504-512
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    • 1990
  • In experiment 1, dietary self-selection of the 3 macronutrients, protein, fat, and carbohydrate were examined in male rats given 3 food cups of 80% carbohydrate, 80% protein, and 70% fat diets simultaneously. All the rats showed normal growth pattern and organ weight, which means they have ability to select just right kinds and amounts of nurients in order to support their growth and development. Mean values of caloric intake, body weight gain, serum lipid values and empty carcass compositions were not significantly differ between the upper and lower quartile groups of fat proportion of empty carcass compared to the lower quartile group(LF). Same feeding design was employed in experiment 2 where the effect of mild electric stress on food selection was studied. The rats in both control and electric stress group revealed a normal growth curve and organ weights. The rats in both control and electric stress group revealed a normal growth curve and organ weights. The stress group showed higher caloric intake and body weight gain than control group, but no significant effects of stress on serum and empty carcass components was found. Even though normal rats seemed to select macronutrients according to their physiolosical needs, there were individual differences in food selection whether they were exposed to stress or not. Therefore life long individual food selection pattern may have a great influence on nutritional status and chronic degenerative diseases of eldery, and on aging process.

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폴리머폼의 압력종속항복조건에 관한 연구 (Pressure-Dependent Yield Criterion For Polymeric Foams)

  • 이희봉
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2000년도 춘계학술대회논문집
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    • pp.17-20
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    • 2000
  • Polymeric foams are excellent energy absorber and have found a wide range of applications especially in the automotive industry. The purpose of the present study is to develop experimental and theoretical methodology to characterize the pressure dependent yield behavior of polymeric foams. For the compression test in a triaxial stress sate a specially designed device was placed in a press machine to produce and control oil pressure. From the experiment results it was observed that the size of Mother circles is changed with mean normal stress in contrast to general metal. Then the Coulomb-Mohr criterion was applied to the data.

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폴리머 폼 재료의 정수압 종속 항복조건 결정에 관한 연구 (Determination of pressure-Dependent Yield . Criterion for Polymeric Foams)

  • 김영민;강신일
    • 소성∙가공
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    • 제11권1호
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    • pp.69-74
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    • 2002
  • In addition to lightweight and moldable characteristics, polymeric foams possess an excellent energy absorbing capability that can be utilize for a wide range of commercial applications, especially in the crashworthiness of the automobiles. The purpose of the present study is to develop experimental methodology to characterize the pressure dependent yield behavior of the energy absorbing polymeric foams. For the compression test in a triaxial stress sate, a specially designed device was placed in a hydraulic press to produce and control oil pressure. For the test material, the polyurethane foams of two different densities were used. The displacement of the specimen, the load subjected to the specimen, and oil pressure applied to the specimen were measured and controlled. Stress strain curves and yield stresses for the four different oil pressure were obtained. It was found from the present experiments that the polyurethane foams exhibited significant increases in yield stress with applied pressure or mean normal stress. Based on this observation, a yield criteria which included the effect of the stress invariant were established for the polymeric foams. The obtained experimental constants which constituted the pressure-dependent yield criterion were verified.

Turbulence Characteristics in a Circular Open Channel by PIV Measurements

  • Kim, Sun-Gu;Sung, Jae-Yong;Lee, Myeong-Ho
    • Journal of Advanced Marine Engineering and Technology
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    • 제35권7호
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    • pp.930-937
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    • 2011
  • The characteristics of mean velocity and turbulence have been analyzed in the circular open channel flow using PIV measurement data for a wide range of water depth. The measured data are fitted to a velocity distribution function over the whole depth of the open channel. Reynolds shear stress and mean velocity in wall unit are compared with the analytic models for fully-developed turbulent boundary layer. Both the mean velocity and Reynolds shear stress have different distributions from the two-dimensional boundary layer flow when the water depth increases over 50% since the influence of the side wall penetrates more deeply into the free surface. The cross-stream Reynolds normal stress also has considerably different distribution in view of its peak value and decreasing rate in the outer region whether the water depth is higher than 50% or not.

관원(關元).중완(中脘).족삼리(足三里) 애구(艾灸)가 수송(輸送) Stress를 준 Rat의 혈액상(血液狀)에 미치는 영향(影響) (Effect of Moxibution at the Kwanwon, Chung-wan and Chok-samni on the blood picture in Rat with transportation stress)

  • 양승희;이준무
    • 대한한방내과학회지
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    • 제15권1호
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    • pp.165-175
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    • 1994
  • Effects of moxibution at the Gwanweon, Jungwan and Joksamlee on the blood picture in rat with transportation stress were determined. Counts of RBC showed a tendency to increase from 6 hours to 12 hours after transportation stress, however in the moxibution group, showed no changes in counts of RBC after transportation stress and the tendency of fluctuation was similiar to those of none stress group. The changes in Hb after transportation stress showed no difference among moxibution group and none moxibution group, however the changes in PCV showed a tendency to increase from 3 hours to 6 hours after transportation stress in two stress group. In the mean values of erythrocytic blood during experimental times, counts of RBC showed a high values (P<.05) in the stress only group, however in the other groups, these values showed no difference (P>.05) among treatment and the values of Hb and PCV showed no difference among 4 treatment groups. In the two stress groups, counts of WBC and Neutrophils showed a tendency to decrease after transportation stress, however the moxibution group was recovered to normal Leukocytes condition on short time compared with those of none moxibution group. In the mean values of Leukocytes during experimental times, counts of WBC and Neutrophils showed a high values and Lymphocytes showed a low values in the stress only group compared with those of other groups, however the stress group with moxibution showed no difference in Leukocytes values compared with those of normal condition group. Monocytes, Basophils and Eosinophils showed no difference among 4 treatment groups(P>.05). Results from this study indicate that the moxibution can tolerate the effects of transportation stress in rat.

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P1ane Strain Strength of Fine Sands

  • Yoon, Yeo-Won;Van, Impe W.F
    • 한국지반공학회지:지반
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    • 제12권3호
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    • pp.5-16
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    • 1996
  • 실리카질 모래에 대한 많은 시험결과로부터 삼축압축시첩과 평면변형시험간의 강도관계를 밀도와 파괴시 유효평균주응력의 함수로 표현하였다. 또한 파괴시 평균주응력과 축차응력간의 응력비가 내부마찰각의 함수로 잘 규정되었으며 그 비는 내부마찰각의 증가에 따라 감소하였다. 또한 중간주응력을 최대주응력과 최소주응력으로써 표현하였으며 이론적인 파괴면의 각도와 평면변형시험에서 관찰된 파괴면의 각도가 비교적 잘 일치함이 확인되었다.

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여성의 긴장성 요실금에 관한 연구 (A Study on Stress Incontinence in Women in Korea)

  • 이영숙
    • 모자간호학회지
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    • 제4권1호
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    • pp.12-23
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    • 1994
  • This study was done to determine the situations of stress incontinence(SI) and the differences in general characteristics, obstetrical history and SI related variables between women with stress incontinence and normal women. The design for study was a descriptive study. The number of subjects consisted of 156 women who were selected by systematic random sampling in Kwangju city. Data collection was done with the modified Hendrickson's Stress Incontinence Scale(1981) which was analyzed using frequency and percentiles. The results were as follows : 1. The stress incontinence (SI) rate of the sample was 64.1% and the majority of the women(40.9%) had experienced SI for a period of five years(the mean period was 2.7 years) without any treatment or care(83.0%). The amount of SI was from one drop(40.0%) to one teaspoon(16.7%) daily. 2. Items on the SI scale had the scores ranging from 4 to 44 with a mean score of 13.7 which showed mild SI. 3. The priority of provocative factors for SI were abdominal tightening(83%), coughing(58%), laughing(52%), sneezing(40%), steeping(18%), sudden standing(17%), nose blowing(13%), heavy exercise(11%), rapid walking up-stairs(10%) and excitment (9%) in that order. 4. There were no significant differences in age, education, spouse, job and income between the women with SI and the normal women. 5. There were no significant differences in the age at the last delivery, age of last baby. number of vaginal, or cesarean deliveries, or abdominal operations between the women with SI and the normal women. It can be concluded that SI in women has a high incidence nth various provocative factors but it is relatively mild SI on a daily basis and generally there has been no treatment. It is suggested that a descriptive study of emotional problems and precipitating variables in SI women will increase the knowledge of SI.

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