• 한국지반공학회논문집
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• 제28권9호
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• pp.69-83
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• 2012

국내에서 출토빈도가 높은 9개 암종을 대상으로 침투에 의한 함수시 강도저감에 대한 연구를 시행하였다. 함수에 의한 강도저감은 암종에 관계없이 암석강도에 지배된다는 사실을 확인하였다. 강도가 약한 암일수록 강도저감 민감도가 예민함을 알 수 있다. 강도에 따라 0.5%의 함수비에 50% 내외의 강도 저감현상이 발생하는 일은 매우 흔하게 관찰된다. 대부분의 암석은 포화함수비의 1/4~1/2의 포화에서 파괴가 일어난다는 사실도 확인할 수 있었다. 함수시 암석강도의 약화는 교질물질의 접착강도 약화와 용탈에 의한 것으로 사료된다.

• Nuclear Engineering and Technology
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• 제51권3호
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• pp.769-775
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• 2019

The tensile strength of irradiated 3C-SiC, SiC with artificial point defects, SiC with symmetric tilt grain boundaries (GBs), irradiated SiC with GBs are investigated using molecular dynamics simulations at 300 K. For an irradiated SiC sample, the tensile strength decreases with the increase of irradiation dose. The Young's modulus decreases with the increase of irradiation dose which agrees well with experiment and simulation data. For artificial point defects, the designed point defects dramatically decrease the tensile strength of SiC at low concentration. Among the point defects studied in this work, the vacancies drop the strength the most seriously. SiC symmetric tilt GBs decrease the tensile strength of pure SiC. Under irradiated condition, the tensile strengths of all SiC samples with grain boundaries decrease and converge to certain value because the structures become amorphous and the grain boundaries disappear after high dose irradiation.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 가을 학술발표회 논문집
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• pp.207-214
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• 1997

Strength experimental on mortar which use Quenched Blast-Furnace Slag as aggregate was carried our for a fundamental study of application possibility of Quenched Blast-Furnace Slag as aggregate. It gives the following results. The strength of mortar use Quenched Blast-Furnace Slag is decrease as substitution rate is higher. As W/C rate increase, the strength decrease, but the strength decrease of fine aggregate rate 1:3 is lower than 1:2. The relation with fine aggregate is that the amount of fine aggregate is inversely proportional to strength. Th relation with age is proportional to strength and strength rate of going is lower than general mortar in 28 age the change of strength proportionately with W/C rate is that as W/C rate increases, th strength is drop ; it shows that it has same tendency as general mortar sand or crushed sand, but while W/C rate increase the strength is as high as general mortar. The reason can be assumed that water content per unit needed to Quenched Blast-Furance Slag is more than in case of sand. In addition, the relation with substitution rate is that the strength is the strongest at substitution rate 25% and 50% ; that is , sometimes it is higher than mortar which use sand 100%. In addition, long age strength of mortar which use Quenched Blast-Furnace Slag as aggregate is about to be studied in the last.

• 한국학교ㆍ지역보건교육학회지
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• 제24권4호
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• pp.27-37
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• 2023

Objectives: The purpose of this study was to investigate the effect of handgrip strength level on cognitive impairment in hypertensive patients. Methods: This study used the first to eighth year data of the Korean Longitudinal Study of Aging (KLoSA). Of the 10,254 respondents who participated in the basic survey, respondents were included that they were diagnosed with high blood pressure and had no cognitive impairment. The handgrip strength was based on the highest value of handgrip strength for both hands. Cognitive function using MMSE results and 23 points or less were defined as cognitive impairment. Cox models were conducted to estimate the hazard ratios (HRs) of cognitive impairment in relation to handgrip strength adjusting for covariates. Results: In the case of hypertension patients, the probability of cognitive decline decreased by 3.0% every time the maximum handgrip strength increased by 1 unit. In the analysis by age, under the age of 64 had a 1.8% decrease in the probability of cognitive decline whenever the maximum handgrip strength increased by 1 unit, and a 3.6% decrease in those over the age of 65. In the gender analysis, male had a 3.2% decrease in the probability of cognitive decline for every 1 unit increase in the maximum handgrip strength, and female had a 2.6% decrease. Conclusions: The results of this study are expected to be used as basic data for the development of interventions to prevent cognitive decline in hypertensive patients by identifying the effect of handgrip strength level on cognitive decline. It is also expected to be used as basic data for health education on the necessity of increasing muscle strength for hypertension patients in the community.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 가을 학술발표회 논문집(I)
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• pp.139-144
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• 1998

This study is intended to devolop the self waterproof agents for high performance concrete by analyzing the properties of fresh and hardened mortar with various addition ratios of the inorganic admixture and zinc stearate. As the results of the test, the flow and air content increase with the addition of expansive additives. When the replacement rate of silica fume increases, the flow decreases for the increased viscidity. And the flow and sir content decrease with the addition of zinc stearate. At hardened state, the compressive strength, tensile strength and flexual strength decrease with the addition of expansive additives and zinc stearate. With the increase of silica fume's replacement, they show a little decrease at early age and then increase gradually. Also, absorption and permeability show a steep decrease when zinc stearate is added, and a slack decrease with the replacement of silica fume.

• Structural Engineering and Mechanics
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• 제65권3호
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• pp.343-348
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• 2018

This paper reports mechanical behavior of recycled fine aggregate concretes after high temperatures. It is found that compressive strength of recycled fine aggregate concretes decline significantly as the temperature rises. The elastic modulus of recycled fine aggregate concretes decreases with the increase in temperature, and the decrease is much quicker than the decrease in compressive strength. The split tensile strength of recycled fine aggregate concrete decrease as the temperature rises. Through the regression analysis, the relationship of the mechanical behavior with temperature are proposed, including the compressive behavior, elastic modulus and split tensile strength, which are fitting the test data.

• 대한통합의학회지
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• 제8권3호
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• pp.71-81
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• 2020

Purpose : The purpose of this study is to investigate the instant effect of Kinesio taping on pain decrease and improvement of functional disorder of the subjects who have lumbar instability. Methods : A total of 20 patients (13 men and 7 women) who have lumbar instability were chosen as the subjects. The experiment was conducted by assigning the subjects into Kinesio taping group and placebo taping group. A visual analog scale (VAS) was used to measure back pain and Biering-Sorensen test was applied to measure the muscle endurance of back extensor muscles. A digital dynamometer was used to test the isomeric contraction strength of lumbar extensor muscle. The subject performed single-leg stance and double-leg stance task and their static balancing ability was measured by a testing device that captures the static balancing ability. Results : In a within-group comparison, Kinesio taping group showed a significant decrease of VAS (p<.05) and a significant increase of endurance and strength of lumbar extensor muscle (p<.05). In Kinesio taping group, the shift distance in anterior-posterior sway and medial-lateral sway during the double-leg stance significantly decrease (p<.05). The shift distance in anterior-posterior sway and medial-lateral sway also significantly decreased during the single-leg stance (p<.05). Placebo taping group showed a significant decrease of visual analog scale (p<.05). In a between-group comparison, Kinesio taping group showed a significantly larger decrease of VAS (p<.05), significant larger increase of muscle endurance and muscle strength (p<.05), and significant larger decrease of anterior-posterior sway in the double-leg stance (p<.05), compared to placebo taping group. Conclusion : Application of Kinesio taping to the subjects with lumbar instability produced positive effect of reducing pain, increasing muscle strength and endurance, and improving static balancing ability.

• International Journal of Internet, Broadcasting and Communication
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• 제15권2호
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• pp.187-195
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• 2023

Sarcopenia is a phenomenon in which muscle function, including muscle strength, deteriorates as muscle mass decreases in the process of increasing age. The diagnosis of sarcopenia utilizes total muscle mass and limb muscle mass, and limb muscle mass is expressed as height squared, body weight, and BMI. Each divided value is used as an index, mainly less than 7.23 kg/m2 for men and less than 5.67 kg/m2 for women. Grip strength, standing up from a chair, and walking speed were mainly used as physical function factors, and grip strength less than 27 kg for men and less than 16 kg for women were used as indicators. The limb muscle mass showed a decreasing trend after peaking in the mid-20s in men, and maintaining a gradual peak in women from the mid-20s to the mid-40s, showing a more rapid decline in men. The rate of decrease in muscle mass and strength continues to increase after the age of 20, and muscle strength rapidly decreases after the age of 80. In Korean men, total muscle mass and limb muscle mass show a decreasing trend from the mid-30s, and a more markedly rapid decrease from the age of 60. For women, it remains constant from the age of 30 to the age of 50, then gradually decreases after the mid-50s, and shows a rather rapid decrease after the mid-70s, showing a more gradual decrease than that of men. Men show a sharp decrease from the mid-40s when limb muscle mass is divided by height squared, and women show a marked decrease after 70 years old when limb muscle mass is divided by height squared. Exercise for the prevention and treatment of sarcopenia results in an increase in protein assimilation hormone, an increase in antioxidant activity, a decrease in inflammation, an increase in muscle insulin sensitivity, and an increase in protein synthesis. Resistance exercise is basically used, and aerobic exercise and equilibrium A combination of exercises is effective. In addition, for a more efficient effect of sarcopenia through resistance exercise, it is necessary to supplement nutrition including protein.

• 한국건축시공학회지
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• 제5권3호
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• pp.101-107
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• 2005

This paper reports the contribution of Shrinkage reducing admixture(SRA) to the physical properties and drying shrinkage of concrete. Dosage of SRA is varied with. For the properties of fresh concrete, an increase in SRA dosage results in a decrease in fluidity and air content, while setting time is accelerated. For the properties of hardened concrete, the incorporation of mineral admixture leads to a decrease in compressive strength at early age, whereas after 28 days, the incorporation of fly ash(FA) and blast furnace slag(BS) has greater compressive strength than conventional concrete without admixture. The use of SRA results in a decrease in compressive strength. The incorporation of SRA with every $1\%$ increase causes the decrease of compressive strength by as much as $3\~6\%$. For drying shrinkage properties, the incorporation of FA and BS reduces drying shrinkage slightly. The use of SRA also decreases drying shrinkage. Every $1\%$ of increase in SRA dosage can reduce drying shrinkage by as much as $10\~15\%$

• 기술표준
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• 통권12호
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• pp.67-78
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• 2003

In order to keep a characteristic corrugated fibreboard of fruits and flowers, temperature and humidity change of corrugated fibreboard are analyzed. According to relative humidity rises at fixed temperature, bursting strength of corrugated fibreboard was fallen and double wall corrugated fibreboard appeared greatly the bursting strength decline rate than double faced corrugated fibreboard and edgewise compressive strength of paper more than humidity 80% in rapidly fall. A column crush test of paper became decrease in the high temperature and ordinary temperature strength did over humidity 70% rapidly fallen and strength decrease happened by low temperature 80% slowly fallen and later rapidly. According to ISO standard temperature humidity conditioning (23$\pm$2 , 50$\pm$2%) change, pulp composition difference as to the ring crush strength of a physical strength and generally compare to KS standard increased 5∼8% for the compressive strength, and wet strength reagent was increased 4% inside and out.