• 터널과지하공간
• /
• 제14권5호
• /
• pp.363-372
• /
• 2004

구마모토 안산암을 대상으로 이중 비틀림(DT) 시험을 통해 유도 홈의 단면 형상이 암석의 응력부식지수에 미치는 영향에 대하여 조사하였다. 정변위속도법에서 변위속도가 증가할수록 균열성장속도는 증가하지만 파괴인성계수는 평균 2.07 MN/m$^{3}$2/로 거의 일정하였다. 정변위법을 통하여 유도 홈의 형상이 사각형, 원형, 삼각형인 시험편을 이용하여 얻은 응력부식지수는 각각 평균 37, 36, 38로 홈의 형상에 관계없이 거의 일정한 값을 보이지만 표준편차는 삼각형 홈에서 가장 크게 나타났다. 암석의 DT시험은 중앙부에 유도 홈이 있는 시험편을 이용하는 것이 효과적이지만 광물의 평균입경 이상의 폭을 가진 사각형 단면의 홈을 이용하는 것이 가장 적절하다.

• 농업과학연구
• /
• 제37권3호
• /
• pp.535-542
• /
• 2010

The purpose of this study was to survey and diagnostic the self-related health cognition, stress, culture life and health-related fitness for residents of rural area. For this study, Total 126 people answered by a written questionnaire and took part in health-related fitness test for old adults in rural area. According to the normal distribution, the indexes were divided into five grades(very poor 5, poor 4, average 3, good 2, very good 1). The self-related health cognition(SF-36) was third grades. The index was as same as average old adults in rural area. The old adults stress level was third grades. The degrees of stress were as same as average old adults in rural area. The participation in the culture life was fourth grades. The health-related fitness test were third-fifth grades. The results of this experiment could be functioned as a very important fundamental source in order to establish satisfying health system, social welfare for the old people in rural area. Taken together, it seemed that self-related health cognition, stress level, participation in the culture life and health-related fitness have to be considered and improved. The indexes should be further investigated and some practical method should be developed for the olded people in rural area.

• 한국학교ㆍ지역보건교육학회지
• /
• 제12권1호
• /
• pp.1-20
• /
• 2011

Purpose: The purpose of this study is to analyze factors affecting suicidal ideation of athletes in middle and high school. Methods: The data in this study came from the survey which conducted to 500 students of physical education high school athletes and elite athletes in general school from the beginning of December 2009 to the end of January 2010 in Seoul and Kyunggi. Finally 436 cases was used. The dependant variable is suicidal ideation in this study. And the independent variables are socio-demographic factors, exercise-related factors, school and family environments, stress and depression factor. The analysis method is logistic regression analysis. Finally 436 cases was used. Results: First, the rate of suicidal ideation of athletes in middle and high school was 28.9%. Second, there were significant differences between stress and sex, grades, athletic career, kind of sport, sport skill level, the average exercise time per day, family circumstances, life satisfaction, future expectations. Third, there were significant differences between depression and sex, academic achievements, the average exercise time per day, family circumstances, life satisfaction, future expectations. Fourth, there were significant differences between suicidal ideation and sport skill level, academic achievements, the average exercise time per day, family circumstances, life satisfaction, future expectations. Fifth, the higher level of stress and degree of depression, the more increased the risk of suicidal ideation. Conclusions: Considering the close relationship between suicidal ideation and suicidal attempt, to reduce the suicidal ideation of athletes in middle and high school it is necessary to adjust exercising time properly and to promote life satisfaction. Also to overcome depression and stress support system should be established and to promote self-efficacy cognition strength program should be introduced in the school. So athletes in middle and high school should have confidence and self-confidence on the future.

• 대한인간공학회지
• /
• 제32권5호
• /
• pp.413-420
• /
• 2013

Objective: The objective of this study was to compare one-hand and two-hands lowering activity in terms of biomechanical stress for the range of lowering heights from knuckle height to 10cm above floor level. Background: Even though two-hands lifting/lowering activity of manual materials handling tasks are prevalent at the industrial site, many manual materials handling tasks which require the worker to perform one-hand lifting/lowering are also very common at the industrial site and forestry and farming. Method: Eight male subjects were asked to perform lowering tasks using both a one-handed as well as a two-handed lowering technique. Trunk muscle electromyographic activity was recorded while the subjects performed the lowering tasks. This information was used as input to an EMG-assisted free-dynamic biomechanical model that predicted spinal loading in three dimensions. Results: It was shown that for the left-hand lowering tasks, the values of moment, lateral shear force, A-P shear force, and compressive force were increased by the average 6%, as the workload was increased twice from 7.5kg to 15kg. For the right-hand lowering task, these were increased by the average 17%. For the two-hands lowering tasks, these were increased by the average 14%. Conclusion: Even though the effect of workload on the biomechanical stress for both one-hand and two-hands lowering tasks is not so significant for the workload less than 15kg, it can be claimed that the biomechanical stress for one-hand lowering is greater than for two-hands lowering tasks. Therefore, it can be concluded that asymmetrical lowering posture would give greater influence on the biomechanical stress than the workload effect for one-hand lowering activity. Application: The result of this study may be used to provide guidelines of recommended safe weights for tasks involved in one-hand lowering activity.

• Journal of Korean Neurosurgical Society
• /
• 제61권6호
• /
• pp.689-699
• /
• 2018

Objective : The goal of this study was to compare several parameters, including wall shear stress (WSS) and flow pattern, between unruptured and ruptured anterior communicating artery (ACoA) aneurysms using patient-specific aneurysm geometry. Methods : In total, 18 unruptured and 24 ruptured aneurysms were analyzed using computational fluid dynamics (CFD) models. Minimal, average, and maximal wall shear stress were calculated based on CFD simulations. Aneurysm height, ostium diameter, aspect ratio, and area of aneurysm were measured. Aneurysms were classified according to flow complexity (simple or complex) and inflow jet (concentrated or diffused). Statistical analyses were performed to ascertain differences between the aneurysm groups. Results : Average wall shear stress of the ruptured group was greater than that of the unruptured group (9.42% for aneurysm and 10.38% for ostium). The average area of ruptured aneurysms was 31.22% larger than unruptured aneurysms. Simple flow was observed in 14 of 18 (78%) unruptured aneurysms, while all ruptured aneurysms had complex flow (p<0.001). Ruptured aneurysms were more likely to have a concentrated inflow jet (63%), while unruptured aneurysms predominantly had a diffused inflow jet (83%, p=0.004). Conclusion : Ruptured aneurysms tended to have a larger geometric size and greater WSS compared to unruptured aneurysms, but the difference was not statistically significant. Flow complexity and inflow jet were significantly different between unruptured and ruptured ACoA aneurysms.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2006년도 정기 학술대회 논문집
• /
• pp.159-166
• /
• 2006

Although the strain distribution along the length of a beam in buildings or infrastructures is non-uniform, most fiber optic sensors are point sensors that can measure the strain only at a local point of a beam. Long gage fiber optic sensors that measure integrated strain over a relatively long length can consider strain variation. This type of sensor was found to be efficient and useful for monitoring large-scale structures. On the other hand, the maximum strain or stress in a beam can not be measured with long gage optic sensors. However, for the assessment of the safety of multi-span steel beams subjected to various vertical loads, the maximum strain or stress measured during monitoring is required for comparison with the allowable stress of the beam calculated by a design code. Therefore, in this paper, mathematical models are presented for determination of the maximum values of strains in more three-span steel beams based on the average strains measured by long gage optic sensors.

• 기본간호학회지
• /
• 제11권1호
• /
• pp.82-91
• /
• 2004

Purpose: The purpose of this study was to identify health promoting behavior and life satisfaction in rural elderly people. Method: The data were collected from October 1st 2002 to October 31th, 2003. The participants were 142 elderly people living in Hong Cheon, Korea. Data were collected using structured questionnaires and analyzed using the SPSS program. Result: The average score for the health promoting behavior was 2.64 (${\pm}0.34$), with a minimum of 1.48 and maximum of 3.80. The average scores for each subscale were, nutrition, 2.98, interpersonal support, 2.78, health responsibility, 2.67, self-actualization, 2.66, stress management, 2.58, and exercise, 1.93. Signifiant differences in health promoting behavior were found according to the following general characteristics: education level, religion, senior citizens center usage and allowance. The average score for life satisfaction was 2.68 (${\pm}0.42$), with a minimum of 1.38 and a maximum of 3.85. Senior citizens center usage was the only general characteristics that showed a significant difference for life satisfaction. There was a significant positive correlation between health promoting behavior and life satisfaction (r= 0.5783, p=0.001). Self-actualization and stress management had statistically significant casual effects on life satisfaction ($R^2$=0.3961). Conclusion: Effective methods to enhance life satisfaction of rural elderly should emphasize self-actualization and stress management.

• 접착 및 계면
• /
• 제21권1호
• /
• pp.20-26
• /
• 2020

Single lap-shear joints (SLJ) specimens with and without partial round fillets were fabricated to measure the average shear strength of adhesives. The effects of the length of the adherend on the SLJ specimens were also investigated. An epoxy adhesive was used to bond aluminum alloy. Tensile tests were performed on the adhesive bulk specimens to measure the mechanical properties. The finite element analysis (FEA) method was used to measure the adhesive stress distributions, i.e., the peel and shear stresses, on the bonded part. The experimental results revealed that the specimen consisting short length of adherend and without the partial round fillets exhibited the smallest average shear strength of adhesive among the investigated specimens. FEA revealed that the low average shear strength for the specimen with a short adherend length was caused by high stress concentrations on the adhesive at the edge of the bonded part.

• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2016년도 학술발표회
• /
• pp.445-445
• /
• 2016

급변하는 개수로 흐름에서 발생하는 바닥전단응력의 분포는 하천구조물 설계에 있어 매우 중요한 요소이다. 하천 구조물 중 호안에 대한 하천설계기준 '설계편 제 24장 호안'에는 호안 설계에 대한 일반적인 사항이 제시 되어 있으나, 구체적인 소류력 또는 유속에 대한 기준, 각 호안공법들의 안정성을 평가하기 위한 시험법 등에 대한 구체적인 기준이 부족한 상황이다. 소류력 측정방법에는 간접측정법과 직접측정법이 있다. 간접측정법에는 Reach-Average공식, Reynolds Stress, TKE공식 (Turbulent Kinetic Energy)이 있고 직접측정법에는 Shear Meter, Preston Tube 등이 있다. 본 연구에서는 바닥전단응력을 직접 측정할 수 있는 1차원 소류력 측정장치를 개발하고, 최대유속 5m/s 가변형 고속수로 실험을 통하여 Reach-Average 공식, Reynolds Stress, TKE 공식으로 산정한 바닥전단응력 값과 1차원 소류력 측정장치 값을 비교 분석하였다. 실험케이스는 총 3개로, 22.42???, 30.00???, 41.00??? 유량을 사류이면서 난류인 상태로 실험을 수행하였다. 분석 결과, 본 연구에서 개발한 1차원 소류력 측정장치의 측정값은 TKE공식과 약 2.3% 차이가 났으며, Reach-Average공식과 약 8.1%, Reynolds Stress는 약 22.1% 차이가 났다. 즉, 본 연구에서 개발한 1차원 소류력 측정장치는 유속 범위(1m/s ~1.6m/s )에서 TKE공식을 이용한 바닥전단 응력과 가장 근사하게 나타나는 것으로 분석되었다.

• Korea-Australia Rheology Journal
• /
• 제12권3_4호
• /
• pp.157-163
• /
• 2000

We develop a simple model which can describe and explain abnormal stress relaxation of ABS melt for which stress dose not exponentially decay. The relaxation behavior of ABS melt consists of two distinct relaxation modes. One is the relaxation of the matrix phase similar to the case of homopolymer melt. The other is manifested by the collection of butadiene rubber particles, named as the cluster, where the particles are connected through the interaction between grafted SAN and matrix SAN. The second mode of the relaxation is characterized by the relaxation time, which is a function of the average size and the microscopic state of the cluster. Experimental results reveal that it can be represented as the product of the average size of the clusters by a function of internal variable that represents the fraction of strained SAN chains inside the cluster.