• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 1994년도 가을 학술발표회 논문집
• /
• pp.127-132
• /
• 1994

This study attemps to investigate the influence of heat of hydration occured during hardening on the strength development of high strength concrete. The concrete design strengths of 500kg/$\textrm{cm}^2$ and 700kg/$\textrm{cm}^2$ were considered to simulated the square columns having $80\times80cm$ and $100\times100cm$, respectively. Both standard curing and field curing specimen were prepared at the specified ages, and the cores were drilled out from the structure. The thermal sensors were installed into the specimen to measure the heat of hydration process occurred during the hardening. This paper tries to uncover the relationship between the temperature history of the concrete and strength development. The correlation of core strength and specimen strength with curing condition is also discussed. Further research is desired to enlight the relationship between strength and heat of hydration of high strength concrete.

• 한국유통학회지:유통연구
• /
• 제15권1호
• /
• pp.73-101
• /
• 2010

본 연구는 유대강도, 공유된 목표, 신뢰와 같은 사회자본이 경제적 성과와 비경제적 성과인 관계지속의도에 미치는 영향에 대하여 부산지역 프랜차이즈 가맹점을 대상으로 공변량 구조방정식모형을 통하여 실증분석하였다. 그 결과 첫째, 유대강도는 관계지속의도에 직접적인 영향을 미치지는 못하지만 신뢰와 경제적 성과를 매개로 간접적으로 긍정적인 영향을 미치는 것으로 나타났다. 둘째, 공유된 가치는 관계지속의도에 직접적인 영향은 물론 신뢰를 매개로 간접적으로 긍정적인 영향을 미치는 것으로 나타났다. 하지만 공유된 목표가 경제적 성과를 매개로 하여 관계지속의도에 영향을 미치지 않는 것으로 나타났다. 마지막으로 이러한 결과들을 토대로 본 연구의 이론적 실무적 시사점을 제시하였다.

• 콘크리트학회논문집
• /
• 제22권4호
• /
• pp.481-488
• /
• 2010

횡구속된 고강도 콘크리트의 역학적 거동을 예측하기 위해 보통강도 콘크리트의 구성모델을 적용할 경우 연성 거동이 과대평가된다. 이러한 문제를 해결하기 위해 콘크리트 강도가 증가함에 따라 구속효과에 미치는 영향을 고찰하여 고강도 콘크리트에 적용 가능한 정확한 응력-변형률 관계가 요구된다. 따라서 이 연구에서는 횡구속된 고강도 콘크리트의 강도와 연성 거동에 양향을 미치는 변수들의 회귀분석을 통한 변수별 회귀식을 바탕으로 새로운 횡구속된 고강도 콘크리트의 구성모델이 제안된다. 횡구속된 고강도 콘크리트의 강도 및 초기강성을 나타내는 응력-변형률 곡선의 상승부는 제안된 구성모델과 잘 일치하였고 연성 거동을 나타내는 하강부 곡선은 원형 단면을 가지는 낮은 횡구속 철근의 항복강도 및 철근비일 때 과대평가되었다. 콘크리트 강도를 주요 변수로 하는 제안된 구성모델은 문헌분석을 통한 25개의 횡구속된 고강도 콘크리트 기둥의 실험적 연구와 비교 분석한 결과 콘크리트 압축강도 60~124 MPa 범위에서의 응력-변형률 곡선과 잘 일치되었다.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2006년도 춘계 학술발표회 논문집
• /
• pp.402-413
• /
• 2006

Strength evaluation of soft soils is a formidable task because of difficulties in sampling, specimen preparation and setting in triaxial cells. In undrained triaxial testing, sampling disturbance, verticality of specimen and bedding effect give a great influence on shear strength measurements. In the other hand, shear wave measurements of specimens are less influenced by these factors. In this research, the bender elements were attached top cap and base pedestal of triaxial cell and shear wave velocities were measured. To initiate a methodology to evaluate shear strength indirectly by measuring shear wave velocity, a relationship between shear strength and shear wave velocity was developed with kaolinite specimens consolidated in the laboratory. Undrained shear strength turns out to increase linearly with shear wave velocity. Stress-strain curves can also be predicted with a hyperbolic model and shear wave measurements.

• 한국가구학회지
• /
• 제12권1호
• /
• pp.21-26
• /
• 2001

This study was carried out to get some basic information on mechanical properties of Platanus orientalis L. for the rational utilization of this wood. Relationship of anatomical characteristics with compression strength parallel to grain was analyzed using stepwise regression technique. All possible combination of 8 independent variables were regressed on compression strength parallel to grain. The summarized results in this study were as follows: 1. The compression strength parallel to grain increased with the increase of wood fiber length and wood fiber width. The strength, however, decreased with increase of number of pore per $\textrm{mm}^2$ and tangential diameter of pore. 2. The major factors affecting compression strength parallel to grain in heartwood were length of wood fiber and number of pore $per{\;}{\textrm{mm}^2}$ but width of wood fiber and length of vessel element were the important factors in sapwood.

• 콘크리트학회논문집
• /
• 제11권4호
• /
• pp.137-145
• /
• 1999

The use of steel fiber reinforced to improve the strength and flexural toughness of concrete is well known, but reinforcement of polymer concrete with steel fibers has been hardly reported till now. Polymer concrete has high strength, durability and freeze-thaw resistance than that of cement concrete, but it has disadvantage such as low flexural toughness. In this paper, the strength characteristics and flexural toughness of steel fiber reinforced polymer concrete are investigated experimentally with various steel fiber aspect ratios($\ell$/d), and contents(vol.%). As the result, the flexural and splitting tensile strengths and flexural toughness were increased aspect ratio, and reach the maximums at a aspect ratio of 50. The relationship between the compressive, flexural and splitting tensile strength were high. And the relationship between flexural strength and strain energy was approximately linear.

• Nutritional Sciences
• /
• 제4권2호
• /
• pp.112-119
• /
• 2001

This study was performed fir the purpose of finding the relationship between fat-free mass (FFM) which mainly represents muscle mass change, and muscle strength. The correlation between diet and exercise behaviors and FFM in healthy elderly men over age 55 was also investigated. FFM and corresponding hand grip strength declined significantly with increasing age. However the concentration of serum albumin, the indicator of protein nutritional status, showed no change with increases in age. The subjects were categorized into three groups according to FFM textiles. Anthropometry such as height, BMI, circumferences of waist and hips, body fat mass percent and hand grip strength decreased significantly in the lowest FFM group. But albumin level showed no change relative to FFM level. FFM showed a significant relationship to nutrient intake such as energy and fat. However, no association was found with exercise behavior probably because there were no instances of resistance exercise habits among the subjects studied. The variance in FFM could be attributed 86.2% to height and age. The variance of height-adjusted FFM could be attributed only 40.6% to age and fat intake. In conclusion decreases in FFM may cause reductions in muscle strength in elderly men. Increasing energy and fat intake were associated with increased FFM and may protect elderly men from the risk of sarcopenia. FFM had no association with endurance exercise habits.

• Journal of Nutrition and Health
• /
• 제34권4호
• /
• pp.449-457
• /
• 2001

This study was performed to show change of fat-free mass(FFM), representing mostly the muscle mass change, and muscle strength with increasing age, and relationship between dietary, exercise behaviors and FFM in healthy middle-and old aged women who are of age over 55 years. The FFM and correspondingly hand grip strength showed significant positive correlation with age. But concentration of serum albumin showed no significant relationship with age. The subjects were categorized into groups according to FFM tertile. The anthropometry such as weight, BMI, fat mass, circumferences of waist and hip, WHR, and hand grip strength decreased significantly in the lowest FFM group. But the albumin level showed no change according to FFM level. The FFM showed significant correlation with nutrient intakes such as energy, carbohydrate, protein, Fe, P, Ca. No association, however, was shown with exercise behavior probably because of no case with resistance exercise habits. The variance of FFM was explained 55.2% by height and carbohydrate intake. The variance of height-adjusted FFM could be explained only 16.2% by intake amount of carbohydrate. In conclusion, the decrease of FFM may cause to reduce muscle strength in female elderly. The increasing nutrient intakes were associated with the increased FFM and may protect from risk of sarcopenia. However, only the carbohydrate intake could influence independently the FFM in middle- and old-aged women. The FFM has no association with endurance exercise habits. (Korean J Nutrition 34(4) : 449∼457, 2001)

• 아동학회지
• /
• 제36권4호
• /
• pp.111-127
• /
• 2015

This study was conducted in order to model the relationship between children's ego strength and their school adjustment and life satisfaction levels. For this purpose, 4,765 4th-6th grade elementary school children were surveyed by means of a questionnaire. The collected data were analyzed by means of structural equation modeling. The results of this study may be summarized as follows. First, in all the grades, a significant and positive correlation was observed between the children's ego strength and their school adjustment and life satisfaction levels. Second, ego strength was found to be a variable that had a significant effect on life satisfaction indirectly through the medium of school adjustment. Third, the relation model between the variables differed according to grade. That is, the direct effect of ego strength on life satisfaction was stronger in the high grades, and the level of school relationship adjustment was found to have a significant effect on family relationship satisfaction as a factor of life satisfaction in 4th graders, whereas it did not in the case of 5th and 6th graders.

• 한국방재학회 논문집
• /
• 제10권2호
• /
• pp.39-46
• /
• 2010

본 연구에서는 조골재, 세골재 및 시멘트량을 달리한 포장용 콘크리트 시편에 대한 강도시험을 통해 물성 정량화 모델식을 제시하였다. 관계식으로는 압축강도와 휨강도, 압축강도와 쪼갬인장강도, 압축강도와 탄성계수 그리고 휨강도와 쪼갬인장강도의 상관관계식을 제시하였다. 모델식에 사용된 데이터는 총 61~81개 조합으로서, 1개 조합에 사용된 시편은 3-4개이었다. 아울러 제시된 상관관계 모델식을 사용하여 고속도로 10개 현장과 국도 4개 현장의 LTPP 구간에서 얻은 코어시편의 탄성계수를 추정하는 절차를 제시하였다. 변동성을 감안하여 본 연구에서는 각 LTPP 구간을 대표하는 탄성계수로서 압축강도에서 탄성계수로 환산한 값과 코어 시편을 사용하여 스트레인게이지에 의해 측정된 탄성계수의 평균값을 사용함으로 인해 코어시편으로부터 발생될 수 있는 측정오차를 줄일 수 있는 방안을 제시하였다.