• 한국노년학
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• 제39권3호
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• pp.549-567
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• 2019

본 연구는 노인의 상대적 악력과 인지기능 간 관계를 경제활동과 사회참여가 조절하는지를 규명하는데 목적을 두고 있다. 한국노동연구원에서 실시한 2016년 제 6차 고령화연구패널 자료를 이용하여 65세 이상 노인 가운데 두 손 모두 수술 및 외상 경험이 없고 악력이 측정 가능한 상태인 총 3,376명을 선정하였다. 모든 인구를 대표하기 위해 횡단 가중치를 적용하였고 통제변수, 독립변수, 조절변수와 상호작용항을 투입하여 위계적 회귀분석을 실시하였다. 연구결과 노인의 상대적 악력이 인지기능에 정적인 관계를 보이고 경제활동과 사회참여도 인지기능에 정적인 관계를 보였다. 또한 노인의 경제활동과 사회참여가 각각 노인의 악력과 인지기능 간의 관계를 조절하는 것으로 나타났다. 특히 악력이 낮더라도 경제활동과 사회참여를 할수록 인지기능에 미치는 부정적인 영향을 완충하는 것으로 나타났다. 이러한 연구결과는 노인의 인지기능 저하에 대응하기 위한 경제 활동과 사회참여에 따른 활동적 노화의 필요성을 시사한다.

• 자원리싸이클링
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• 제22권1호
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• pp.20-28
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• 2013

국내 자동차 사용이 증가하면서 폐타이어의 재활용에 대한 관심이 고조되고 있다. 폐타이어의 재활용을 위한 처리방법중 분말가공 형태는 25%로서 건설현장에서 다양하게 사용되고 있다. 본 연구에서는 황과 폐타이어를 이용한 콘크리트(SRC: Sulfur-Rubber Concrete)의 물리적 특성을 파악하여 최적배합비를 제안하는데 그 목적이 있다. 이를 위해 황과 폐타이어의 배합양을 달리하여 압축강도 실험을 수행하였다. 더불어 SRC의 제작과정을 2개의 배합방법(건조배합과정 및 습윤배합 과정)에 따라서 각각 그 특성을 평가하였다. 그 결과 고무의 혼입률이 증가할수록 SRC의 압축강도는 감소함을 알 수 있었으며, 마이크로 충진재의 첨가와 황 혼입률 조절은 압축강도를 향상시켰다. 또한 SRC의 황의 혼입률을 조절하여 강도의 최적값을 제안하였다. 이러한 SRC는 도로포장이나 경량벽체 또는 충격에너지 흡수율이 높은 건설 분야에 적용될 수 있을 것으로 판단된다.

• 성인간호학회지
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• 제20권4호
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• pp.537-547
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• 2008

Purpose: The study aimed to apply Tai Chi exercise to patients with coronary artery disease for 6 months, and to examine changes on body composition, physical strength, and cardiovascular risks. Methods: Applying a quasi experimental design with a nonequivalent control group, 90 subjects with cardiovascular disease were recruited at C university hospital. For 6 months, 44 subjects performed Tai Chi exercise once a week and daily home exercise, while 46 subjects did not. Body composition was assessed by body mass index, % body fat, and waist-hip ratio; physical strength by balance, mobility, flexibility, grip strength, and back muscle strength; and cardiovascular risk checklist for fixed and modifiable risk factors. Data were analyzed by SPSS/WIN program with ANCOVA to consider group differences at the pretest. Results: The subjects were 66 years old in average. In 6 months, Tai Chi group improved significantly in balance, mobility, and flexibility with decreased modifiable cardiovascular risks after adjusting for the pretest scores. Conclusion: Tai Chi exercise was safely applicable to individuals with coronary artery disease, and effective in some measures of physical strength and modifiable cardiovascular risks. It could be an alternative exercise for outpatient cardiac rehabilitation program in this population.

• 한국식품영양학회지
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• 제16권2호
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• pp.138-145
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• 2003

난백, bpp, gelatin 및 gluten을 농도별로 첨가하였을 때 페루산과 포클랜드산 오징어 모두에서 각각 4%, 5%, 3% 및 4% 첨가구가 가장 높은 jelly강도를 나타내었고, 그 이상의 첨가에서는 큰 변화가 없었다. 이때의 물성 특성 값들을 보면 절곡시험 값은 모두 B를 나타내어 두겹으로 접어 1/2정도만 균열이 생겼으며, 페루산 오징어 연제품의 경우 수분함량은 72.06~73.78%, 보수력은 88.53~91.11%사이였고, 포클랜드산 오징어 연제품의 경우 수분함량은 71.91~72.89%, 보수력은 90.21~93.25%사이였다. 그리고 가장 높은 jelly강도 값을 나타낸 경우는 bpp를 5% 첨가하였을 때이며 이때 페루산과 포클랜드산 오징어 연제품에서 각각 872$\pm$29g.cm와 982$\pm$26g.cm를 나타내었다. Gluten 4% 첨가의 경우 jelly강도의 증가폭에 비하여 탄력성과 깨짐성의 힘이 크게 나타났으며 보수력도 크게 증가되는데 반해 경도의 변화는 크지 않았으며, 이때의 절곡시험 값은 B, 수분함량은 페루산이 73.74%, 포클랜드 산이 72.89%로 나타났다. 이상의 결과에서 오징어를 이용한 연제품제조시 적절한 단백질류 첨가는 제품의 품질 향상에 효과가 있는 것으로 나타났다.

• 한국건설순환자원학회논문집
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• 제10권4호
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• pp.367-375
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• 2022

순환 잔골재 혼합비율에 따른 압축강도는 설계기준강도별 보통콘크리트 대비 순환 잔골재 혼합비율에 따라 유사하거나 다소 낮은 강도 발현을 보였으며, 순환 잔골재 혼합비율이 증가할수록 압축강도는 감소하는 경향을 보였다. 재령일이 증가할수록 강도저하는 발생하지 않았으며, 설계기준강도 대비 강도 발현이 가능할 것으로 판단된다. 순환 잔골재 15 %, 20 %, 25 %로 혼합비율에 따른 순환골재 콘크리트의 길이변화 및 동결융해에 대한 내구특성은 보통콘크리트와 유사한 경향으로 나타났다. 콘크리트용 순환 잔골재의 비율은 총 골재량의 25 %(총잔골재의 50 %)까지 적용하면 슬럼프 및 공기량에 문제가 없을 것으로 판단되며, 설계기준강도에 따른 분체량과 단위수량 및 공기연행제량에 대한 관리가 필요할 것으로 판단된다.

• 한국농공학회지
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• 제21권2호
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• pp.81-103
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• 1979

The weathered granite soil involves problems in its stability in soil structures depending upon the reduction of soil strength due to the water absorption, crushability, and content of colored mineral and feldspar. As an attemt to solve the problems associated with soil stability, the crushability of weathered granite soil was investigated by conducting tests such as compaction test, CBR test, unconfined compression test, direct shear test, triaxial compression test, and permeability test on the five soil samples different in weathering and mineral compositions. The experimental results are summarized as follows: The ratio of increasing dry density in the weathered granite soil was high as the compaction energy was low, while it was low as the compaction energy was increased. The unconfined compressive strength. and CBR value were highest in the dry side rather than in the soil with the optimum moisture content, when the soil was compacted by adjusting water content. However, the unconfined compressive strength of smples, which were compacted and oven dried, were highest in the wet side rather than in soil with the optimum moisture content. As the soil becomes coarse grain, the ratio of specific surface area increased due to increased crushability, and the increasing ratio of the specific surface area decreased as the compaction energy was increased. The highest ratio of grain crushability was attained in the wet side rather than in the soil with the optimum moisture content. Such tendency was transforming to the dry side as the compaction energy was increased. The effect of water on the grain crushability of soil was high in the coarse grained soil. The specific surface area of WK soil sample, when compacted under the condition of air dried and under the optimum moisture content, was constant regardless of the compaction energy. When the weathered granite soil and river sand with the same grain size were compacted with low compaction energy, the weathered granite soil with crushability had higher dry density than river sand. However, when the compaction energy reached to certain point over limitation, the river sand had higher dry density than the weathered granite soil. The coefficient of permeability was lowest in the wet side rather than in the optimum moisture content, when the soil was compacted by adjusting soil water content. The reduction of permeability of soil due to the compaction was more apparent in the weathered granite soil than in the river sand. The highly significant correlation coefficient was obtained between the amount of particle breakage and dry density of the compacted soil.

• 한국생산제조학회지
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• 제19권2호
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• pp.163-170
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• 2010

We have studied on welding dissimilar materials of cold-reduced carbon steel sheet and stainless steel sheet together by using laser beam. It is well known that stainless steel is so strong againt rust and heat, while cold-reduced carbon steel is widely used in various parts of industry. In this research we have performed some experiments to know the possibility of welding dissimilar materials using laser beam by adjusting the power output of 3kW laser. Other conditions of the experiments were as follows : the welding speed was varied in the range between 2m/min and 7m/min, argon gas and helium gas were used as shield gas, the flow value of shield gas was ranged between $10{\ell}/min$ and $30{\ell}/min$, and the gap of two materials was ranged between 0mm and 0.3mm. In order to ascertain of the welded surface, we have done the tensile strength testing, the hardness testing and the microscope observation. As a result, we have found that tensile strength was the highest at the condition of the welding speed of 4, the flow value of $20{\ell}/min$, the gap of two materials 0, and the use of helium gas. Above testings have also showed that the tensile strength was generally satisfactory since the penetration of welding was almost complete due to the thinness of the materials. In addition, the formation of the welded area was excellent when it had the highest tensile strength.

• 한국화재소방학회논문지
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• 제20권2호
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• pp.80-86
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• 2006

본 고찰은 화재시 고강도 콘크리트의 주요 이슈 중의 하나인 폭열 현상에 초점을 맞추어 폭열의 정의, 분류 및 각각의 특징, 발생원인과 그 반응기구에 대하여 선행연구를 중심으로 분석하였다. 폭열은 급격한 온도 상승, 높은 수분 함유량, 낮은 물시멘트비(W/C), 콘크리트 내에 국부적인 높은 응력 발생 등과 같은 요인이 복합적으로 작용하여 발생한다. 이러한 요인을 토대로 폭열을 방지하기 위한 방법으로 크게 콘크리트의 온도 상승을 억제하는 방법, 콘크리트의 비산을 억제하는 방법, 그리고 빠르게 내부 수분을 건조시키는 방법 등을 들 수 있다. 본 고찰에서는 이러한 방법 가운데 가장 효율적인 폭열 방지 방안으로서 콘크리트 내부의 수분을 빠르게 건조시킴으로써 폭열에 이르게 하는 함수율 이하로 낮추어서 콘크리트 자체의 내폭열성을 높이는 방안을 고찰하였다. 실제 강제건조를 통해 함수율을 어떤 임계치(critical value) 이하로 낮추게 되면 폭열을 방지할 수 있으며 이를 위해서는 수동적인 자연건조 외에 강제건조 등으로 함수율을 낮출 필요가 있을 것이다. 이러한 임계치 결정을 위해 추가적인 많은 실험 및 자료가 도출되어야 할 것이다.

• Journal of Acupuncture Research
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• 제32권1호
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• pp.89-95
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• 2015

Objectives : This study was designed to discover the difference in stimulation effect when the volume and insertion method of mountain ginseng pharmacopuncture was varied. Methods : 48 healthy people were randomly injected with 0.1, 0.3, 0.5, and 0.7 cc of mountain ginseng pharmacopuncture, perpendicularly or transversely at acupoints $LI_9$ and $LI_{10}$. The subjects noted their level of stimulation on a 100 mm visual analog scale(VAS) immediately after, 3 minutes after, and 5 minutes after the treatment. Results : There was no significant statistical difference in the stimulation strength between perpendicular injection and transverse injection pharmacopuncture. There was significant statistical difference in the stimulation strength when the volume of pharmacopuncture was varied. As the volume of pharmacopuncture increased from 0.1 cc to 0.3 cc, and to 0.5 cc, the stimulation strength increased as well. Conclusions : We found that volume of pharmacopuncture may be a controlling element for mountain ginseng pharmacopuncture. Additional study is needed for pharmacopuncture's stimulation adjusting factors.

• 소성∙가공
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• 제30권6호
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• pp.291-300
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• 2021

Currently, starting with electric vehicles, the application of ultra-high-strength steel sheets and light metals has expanded to improve mileage by reducing vehicle weight. At a time when internal combustion engine vehicles are rapidly changing to electric vehicles, the application of ultra-high-strength steel is expanding to satisfy both weight reductions and the performance safety of the chassis parts. There is an urgent need to improve the quality of parts without defects. It is particularly difficult to estimate the part formability through the finite element method (FEM) in the burring operation, so product design has been based on the hole expansion ratio (HER) and experience. In this study, design of experiment (DOE), analysis of variance (ANOVA), and regression analysis were combined to optimize the formability by adjusting the process variables affecting the burring formability of ultra-high-strength steel parts. The optimal variables were derived by analyzing the influence of variables and the correlation between the variables through FE analysis. Finally, the optimized process parameters were verified by comparing experiment with simulation. As for the main influence of each process variable, the initial hole diameter of the piercing process and the shape height of the preforming process had the greatest effects on burring formability, while the effect of a lower round of punching in the burring process was the least. Moreover, as the diameter of the initial hole increased, the thickness reduction rate in the burring part decreased, and the final burring height increased as the shape height during preforming increased.