• 한국건축시공학회지
• /
• 제23권5호
• /
• pp.509-517
• /
• 2023

철근 부식을 해결하기 위해 FRP에 관한 연구가 증가하고 있다. CFRP는 경량화로 시공성이 용이하며, 내식성 및 내화학성이 뛰어나 이형철근 대체제로 지목되고 있다. 하지만 CFRP는 섬유와 레진을 압착하여 만들어져 열에 취약한 단점이 존재한다. 이러한 CFRP에 관한 연구는 미비한 실정이며, 본 연구에서는 고온 가열 이후 CFRP와 GFRP의 부착강도에 관한 연구를 실시하였다. 그 결과 규사코팅 CFRP와 리브형 CFRP, GFRP 모두 비슷한 부착강도 발현을 보였다.

• 한국건축시공학회지
• /
• 제12권2호
• /
• pp.183-193
• /
• 2012

Compressive property of high strength concrete with amorphous metal fibers subject to high temperature has been investigated. The measure of this investigation includes explosive spalling, weight loss, residual compressive strength, strain at peak stress, elastic modulus, and residual energy absorption capacity after exposure to $400^{\circ}C$, $600^{\circ}C$and $800^{\circ}C$. In addition to the amorphous metal fiber, two other types of fibers (polypropylene fiber and hooked-end steel fiber) were also included in this investigation for comparison. The experimental program was conducted with high strength concrete using several combinations of the fiber types. The testing result shows that the concrete with amorphous metal fibers plus polypropylene fibers shows a superior behavior than those using other combination or single fiber type ingredient.

• 한국광학회:학술대회논문집
• /
• 한국광학회 2009년도 동계학술발표회 논문집
• /
• pp.147-148
• /
• 2009

We have fabricated a down tapered polymer tip on optical fiber end-face by a guided UV light. One side of fiber was aligned with a mercury-xenon lamp and another was put into UV curable polymer. A shape of tip was controlled by adjusting an irradiance of lamp and time of exposure. A bending effect also affects the result. Optical characteristic was achieved preliminarily with solution of minute particles.

• 한국광학회:학술대회논문집
• /
• 한국광학회 2008년도 동계학술발표회 논문집
• /
• pp.251-252
• /
• 2008

We fabricated silica glass optical fiber containing PbSe quantum-dots (QD) of average size 3.2 nm. The response time of the PbSe-QD doped optical fiber was measured to be around 200 ps. However, after exposure to 1064 nm laser emission for 15 minutes, the response time dramatically reduced to around 2.5 ps, which may be due to photo-darkening effect.

• Journal of Preventive Medicine and Public Health
• /
• 제33권4호
• /
• pp.477-483
• /
• 2000

Objectives : To obtain reference values for the pulmonary asbestos and non-asbestos fiber contents of residents in Korea and to compare them with similar results from Japan. Methods : The autopsied lung specimens from 22 deceased people (20 males and 2 females) in Pohang, without any known occupational history of asbestos exposure, were analyzed for incidence of asbestos and non-asbestos fibers by transmission electron microscopy with energy dispersive X-ray analysis after using low temperature ashing procedures. Results : Chrysotite fiber (46.2%) was the major fiber type found in the lungs of the subjects. The asbestos fiber concentrations found in males and females were $0.09\times10^6$ fiberss(g of dry lungs) and $0.30\times10^6$ fibers/(g of dry lungs), respectively, showing a geometric mean concentration $0.09\times10^6$ fibers/(g of dry lung tissue), due to the predominance of males in the sample. The non-asbestos fiber contents in males and females were $4.61\times10^6$ fibers/(g of dry lungs) and $17.79\times10^6$ fibers/(g of dry lungs), respectively, with a geometric mean concentration $5.21\times10^6$ fibers/(g of dry lung tissue). Conclusions : Residents in Pohang had significantly lower levels of both asbestos and non-asbestos fibers than urban residents in Korea. Furthermore, Koreans had significantly lower levels of both asbestos and non-asbestos fibers than Japanese.

• 한국농공학회논문집
• /
• 제59권5호
• /
• pp.73-81
• /
• 2017

The improved movable weir supplements the advantages and disadvantages of the rubber weir and the conduction gate. It consists of a stainless steel gate, air bags, and a steel clamping plate. The stainless steel gate is the main body of the weir, and the inflatable rubber sheet serves to support the steel gate. The steel clamping plate is typically in direct continuous contact with water, but this leads to corrosion issues that can reduce the life of the entire movable weir. In this study, a panel-type glass-fiber-reinforced polymer (GFRP) clamping plate was designed and fabricated. The test results showed that the flexural load of the panel-type GFRP composite clamping plate was over twice that of the wings type GFRP clamping plate. The lowest moisture absorption value was obtained upon exposure to tap water, and exposure to other solutions showed similar values. Additionally, flexural load testing after exposure to an accelerated environment found the lowest residual loads of 80.51 % and 78.50 % at 50 and 100 days, respectively, for exposure to a $CaCl_2$ solution, while exposure to other environments showed residual failure loads of over 80 % at both 50 and 100 days.

• 한국환경보건학회지
• /
• 제24권3호
• /
• pp.35-40
• /
• 1998

This study was conducted to examine the pathological changes of rat peripheral nervous system during exposure to tellurium known to be a demyelinating agent by using teasing nerve fiber method and quantitative light microscopic analysis by image analyzer. The pellet containing 1.2% of tellurium were fed for 3, 5, 7, 9, 13 days to male wistar rats (21 days old) and then neurologic symptom and the feature of nerve fiber myelination were studied. From this study, following results were obtained. In 3 days treated group, it showed various neurologic symptom and teased nerve fiber showed slight irregularity of the myeline sheath. In 5 days and 7 days treated groups, it showed the segmental demyetination in larger size fiber and widening of nodes of ranvier. In 9 days and 13 days treated groups, the remyelinated fibers were observed and it was generally small in size. We consequently suggest that teasing nerve fiber method and quantitative analysis of nerve fiber were useful pathologic screening method of neurotoxicity of the peripheral nervous system.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2014년도 춘계 학술논문 발표대회
• /
• pp.144-145
• /
• 2014

Nowadays, as to increased the workability of the press concrete and decrease the cracking, the fiber-reinforced admixture has been widely used. As the low adhesion force between the paste and fiber-reinforced admixture, it was considered as could not be used in the structure. Even more, as the loss of flowability and the exposure of the fiber, further study is needed. In this study, as the different environment and position of the building, the dosages of the fiber-reinforced admixture has also been changed. The fundamental properties and cracking of fiber-reinforced concrete have been tested.

• Advances in concrete construction
• /
• 제16권1호
• /
• pp.1-20
• /
• 2023

This study presents the experimental results performed to evaluate the effects of Polyvinyl-alcohol (PVA) and Polypropylene (PP) fibers on the fresh and residual mechanical properties of the hybrid fiber reinforced SCC before and after the exposure of 250℃, 500℃ and 750℃ temperatures. The compressive and splitting tensile strength, modulus of rupture (MOR), ultrasonic pulse velocity (UPV) as well as toughness and weight loss were investigated at different temperatures. PVA and PP fibers were added into SCC mixtures having only macro steel fiber and also having binary hybridization of both macro and micro steel fiber. The results showed that the use of micro steel fiber replaced by macro steel fiber improved the fresh and hardened properties compared to the use of only macro steel fiber. Moreover, it was emphasized that PVA or PP enhanced the residual flexural performance of SCC, generally, while it negatively influenced the workability, weight loss, UPV and the residual strengths with regards to the use of single steel fiber and binary steel fiber hybridization. Compared to the effect of synthetic fibers, PP had slightly more positive effect in the view of workability while PVA enhanced the residual mechanical properties more.

• 한국환경보건학회지
• /
• 제14권2호
• /
• pp.13-27
• /
• 1988

Two asbestos slate manufacturing and seven asbestos textile plants in Korea were surveyed from May 20 to July 2, 1987. The purposes of this study were to evaluate 1) worker exposure to asbestos, 2) compliance to the standards and 3) the efficiency of existing local exhaust systems. Sixty-two personal samples and eighty-three area samples were collected and analyzed using "NIOSH 7400" method. Results of this study were as follows. 1. The asbesots exposure concentrations in asbestos textile plants were 1.3 - 14.3 fibers/cc(geometric mean(GM), 4.4 fibers/cc). 2. Worker exposure level to asbestos fiber in asbestos slate manufacturing industry was 0.21 fibers/cc during wet processing, which is below the Korean Standard of 2 fibers/cc. 3. Most local exhaust systems installed in asbestos textile plants were inadequately designed. 4. Ninety-six percent of the 145 samples exceeded the U.S. Occupational Safety and Health Administration (OSHA) Permissible Exposure Limit (PEL) of 0.2 fibers/cc and forty-nine percent of the samples exceeded the Korean Standatd of 2 fibers/cc.