• 복합신소재구조학회 논문집
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• 제6권2호
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• pp.91-96
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• 2015

GRP pipe (Glass-fiber Reinforced Plastic Pipe) lines making use of FRP (Fiber Reinforced Plastic) are generally thinner, lighter, and stronger than the existing concrete or steel pipe lines, and it is excellent in stiffness/strength per unit weight. In this study, we present the result of field test for buried GRP pipes with large diameter(2,400mm). The vertical and horizontal ring deflections are measured for 387 days. The short-term deflection measured by the field test is compared with the result predicted by the Iowa formula. In addition, the long-term ring deflection is predicted by using the procedure suggested in ASTM D 5365(ANNEX) in the range of 40 to 60 years of service life of the pipe based on the experimental results. From the study, it was found that the long-term vertical and horizontal ring deflection up to 60 years is less than the 5% ring deflection limitation.

• 한국콘텐츠학회논문지
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• 제14권7호
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• pp.346-355
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• 2014

본 연구의 목적은 시설거주 여성노인의 일상생활동작이 반영된 기초신체활동을 측정하여 대상자들의 기초신체활동의 기본적인 필수 측정요소와 측정항목을 제시하기 위함이다. 대상자는 대전과 충남에 소재한 장기요양시설 4곳의 만 65세 이상 여성노인 105명이며, 일상생활동작이 반영된 8개 항목(악력, 스텝 테스트, 의자에서 앉았다 일어나기, 한발 서기, 기능적 팔 뻗기, 8자 보행, 5m 보행, 일어서고 걷기)을 측정하였다. 자료는 평균과 표준편차, 요인분석, ANOVA, 그리고 피어슨의 상관관계로 분석하였다. 연령집단 간각 종목의 평균을 분석한 결과 연령이 증가함에 따라 각 측정항목의 결과에 유의한 차이를 나타냈다. 8개 측정항목은 요인분석을 통해 근력과 이동능력 두 영역으로 제시하였다. 시설거주 여성노인에게 중요한 체력요소인 이 근력과 이동능력 영역은 연령이 증가할수록 모두 유의하게 감소하였다. 따라서 시설거주 여성노인의 운동을 위한 간호전략에 있어 근력 및 이동능력의 요소가 고려되어야 하며, 이 두 영역에 대한 측정항목 또한 객관적인 지표가 마련되어야 한다.

• 한국식품저장유통학회지
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• 제20권1호
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• pp.76-80
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• 2013

본 연구는 인삼을 칼슘 및 식초에 침지함으로서 인삼 pectins의 칼슘결합(calcium bonding)에 의한 물성변화를 조사하였다. 인삼뿌리의 강도(strength)와 부서짐성(breakdown)은 탄산칼슘 농도의 증가에 따라 증가하였으나 탄산칼슘 0.7~1.0%에서 가장 높게 나타났고, 인삼뿌리의 경도(hardness)는 탄산칼슘 농도 1.0%에서 가장 높았고, 연화정도(softness)는 탄산칼슘 농도 1.0%에서 가장 낮았다. 1% 탄산칼슘을 용해한 식초에 침지한 인삼뿌리의 물성 중 강도, 부서짐성 및 경도는 산도 5%, 6% 칼슘용액에 침지한 인삼뿌리가 60일 이후부터 계속 증가하여 90일경에 높게 나타났다. 연화 정도는 1% 탄산칼슘과 산도 5% 식초에 침지한 인삼뿌리만이 줄어들어 인삼뿌리음료의 장기저장 중 음료가 혼탁해지는 것을 방지할 수 있었다.

• Advances in concrete construction
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• 제14권3호
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• pp.205-214
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• 2022

Due to seawater's physical and chemical deterioration effects on concrete structures, it is crucial to investigate the durability of these structures in marine environments. In some conditions, concrete structures are exposed to seawater from the first days of construction or because of the lack of potable water, part of the concrete curing stage is done with seawater. In this research, the effects of exposure to seawater after 7 days of curing in standard conditions were evaluated. To improve the durability of concrete, fly ash has been used as a substitute for a part of the cement in the mixing design. For this purpose, 5, 15, and 30% of the mixing design cement were replaced with type F fly ash, and the samples were examined after curing in seawater. The resistance of concrete against chloride ion penetration based on the rapid chloride penetration test (RCPT), water permeability based on the depth of water penetration under pressure, and water absorption test was done. The changes in the compressive strength of concrete in different curing conditions were also investigated. The results show that the curing in seawater has slightly reduced concrete resistance to chloride ion permeation. In the long-term, samples containing FA cured in seawater had up to 10% less resistance to chloride ion penetration. The amount of reduction in chloride ion penetration resistance was more for samples without FA. Whiles, for both curing conditions in the long-term up to 15%, FA improved the chloride ion penetration resistance up to 40%. Curing in seawater slightly increased the penetration depth of water under pressure in samples containing FA, while this increase was up to 12% for samples without FA. In the long-term the compressive strength of samples cured in seawater is not much different from the compressive strength of samples cured in plain water, while at the age of 28 days, due to seawater salts' accelerating effects the difference is more noticeable.

• Smart Structures and Systems
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• 제19권3호
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• pp.335-340
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• 2017

Fiber Bragg grating (FBG) sensors are applied to structural health monitoring (SHM) in many areas due to their unique advantages such as ease of multiplexing and capability of absolute measurement. However, they are exposed to cyclic thermal load, generally in the temperature range of $-20^{\circ}C$ to $60^{\circ}C$, in railways during a long-term SHM and the cyclic thermal load can affect the mechanical strength of FBGs. In this paper, the effects of both cyclic thermal load and the reflectivity of FBGs on the mechanical strength are investigated though tension tests of FBG specimens after they are aged in a thermal chamber with temperature changes in a range from $-20^{\circ}C$ to $60^{\circ}C$ for 300 cycles. Results from tension tests reveal that the mechanical strength of FBGs decreases about 8% as the thermal cycle increases to 100 cycles; the mechanical strength then remains steady until 300 cycles. Otherwise, the mechanical strength of FBGs with reflectivity of 6dB (70%) and 10dB (90%) exhibits degradation values of about 6% and 12%, respectively, compared to that with reflectivity of 3dB (50%) at 300 cycles. SEM photos of the Bragg grating parts also show defects that cause their strength degradation. Consequently, it should be considered that mechanical strength of FBGs can be degraded by both thermal cycles and the reflectivity if the FBGs are exposed to repetitive thermal load during a long-term SHM.

• 대한한방부인과학회지
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• 제21권1호
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• pp.28-38
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• 2008

Purpose: This study was conducted to investigate the muscular strength & stamina improvement and muscle anti-fatigue effects of Morinda officinalis How after long term administration. Methods: 4-6 weeks old ICR mice were used in this study and we administered the water soluble extracts of Morinda officinalis How in the concentration of 1, 10. 100/mg/0.3ml to each 5 mice (ATS group) and same volume of normal saline was administered to 5 mice (control group) once a day for 90 or 120 days. After the administration we performed the swimming exercise test and the grip strength test. And we measured the concentration of glucose and the activity of lactate dehydrogenase in plasma regarded as biochemical indicator related with the muscular fatigue. Results: In swimming exercise test, all ATS groups showed increased time compared with relative control group after 90 days administration. After 120 days adminstration 100/mg/0.3ml ATS groups showed increased results. In grip strength test, all ATS groups showed increased grip strength compared with relative control group after 90 days administration. After 120 days adminstration 10/mg/0.3ml ATS groups showed increased result. All the results of plasma glucose didn't showed statistically significant difference after 90 and 120 days administration. In the plasma concentration of activity level of lactate dehydrogenase, all ATS groups didn't showed statistically significant difference compared after 90 days administration. Conclusion: This study show that Morinda officinalis How can increase the muscular strength & stamina and anti-fatigue effect.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 춘계 학술발표회 제20권1호
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• pp.689-692
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• 2008

본 연구는 친환경 콘크리트의 개발을 위하여 시멘트 대체재료인 혼화재료로서 황토, 슬래그 및 PET보강섬유를 혼입한 콘크리트의 역학적 특성을 분석하는데 목적이 있다. 이를 위하여 콘크리트(SC), 황토콘크리트(HTC), 황토 및 PET보강섬유가 혼입된 시험체(HTPC)를 대상으로 재령별 압축강도 실험을 실시하였으며, 시험체의 장기특성을 분석하기 위한 크리프 및 건조수축 실험을 실시하였다. 실험결과, 재령별 압축강도는 시험체 별로 큰 차이를 나타내지 않았으나, HTC 시험체의 압축강도가 가장 큰 것으로 나타났으며, 크리프 및 건조수축의 실험결과 HTC 시험체의 장기특성이 가장 우수한 것으로 판명되었다.

• 한국지반신소재학회논문집
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• 제16권2호
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• pp.89-96
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• 2017

본 연구에서는 국내에서 30m 이상인 대심도에서 강성이 큰 CS-H벽체를 만들기 위하여 지반신소재를 이용하였으며 지반신소재의 혼입율과 슬럼프(슬럼프 플로우) 값에 변화를 주어 현장여건에 맞는 배합을 실시하였으며 목표 슬럼프 180mm 및 슬럼프 플로우 500mm에서는 초기 휨강도, 장기 거동특성 및 탄성계수의 역학적 특성과 동시에 경제성을 모두 만족할 수 있는 배합을 확인하였으나 슬럼프 플로우 600mm에서는 역학적 특성 및 초기, 장기 거동특성에서 취약한 결과를 보였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.323-328
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• 2002

Rapid set accelerators are widely used in tunnel construction, however quality criteria of and dosage are not well established. The density and solid content of admixtures, setting time and compressive strength of paste and mortar with admixtures were investigated to establish the quality criteria. While the early strength of mortar with sodium-silicate, sodium-aluminate and calcium aluminate type admixtures that have high alkali content are very high, but long-term strength are low. Aggregates of shotcrete has to be carefully selected. Sodium-silicate type admixture need longer setting time than the others.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2001년도 학술발표회 발표논문집
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• pp.193-197
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• 2001

The growth in concrete structures repair has prompted major efforts to develop high early strength concrete. The internal or external restraint of thermal shrinkage movements could thus generate tensile stresses in concrete structures if it is used rapid setting repair concrete. Restrained shrinkage and thermal stresses could produce microcracks in concrete which increase its permeability and accelerate its long-term deterioration under weathering and load effects. This study aims at evaluation and increase of the engineering properties of high early strength concrete using regulated set cement.