• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1995년도 가을 학술발표회 논문집
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• pp.80-83
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• 1995

In order to develope and apply high-performance steel fiber reinforced concrete (SFRC), the effects of steel fibers on durability and long-term deformation of SFRC due to various mixing conditions have been studied. As the test result show, the manufacturing process technology of industrial SFRC is developed And the durability of SFRC such as freeze-thaw, resisteance abrasion resistance are significantly improved, the drying shrinkage of SFRC, is remarkably decreased by increasing the steel fiber contents than plain concrete

• 한국농공학회지
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• 제43권5호
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• pp.124-131
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• 2001

The shrinkage properties of high early strength concrete were investigated. One of the method to control microcrack and crack development due to restrained shrinkage is to reinforce concrete with randomly distributed fibers. Regulated-set cement and two different types of fiber were adopted. The experiments for heat of hydration, drying and autogenous shrinkage were conducted. The desirable resistance of high early strength fiber reinforced concrete to restrained shrinkage microcracking was achieved. These results indicate that use of fiber in high early strength concrete plays an important role in control of crack development due to restrained shrinkage.

• 한국산림과학회지
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• 제44권1호
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• pp.26-35
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• 1979

삼나무 및 편백나무의 산지조림시(山地造林時) 활착율(活着率)아 낮은 경우(境遇)가 왕왕(往往) 있으므로 이들 요인(要因)을 구명(究明)코저 1979년(年) 2월(月)부터 9월(月)까지 삼나무, 편백나무, 1-1실생묘(實生苗)와 삼나무 2-1삽목묘(揷木苗)를 공시목(共試木)으로 실내(室內) 및 주간노지(晝間露地) 건조조건(乾燥條件)과 OED green 및 수침적(水浸積) 조건처리(條件處理)를 하여 활착률(活着率)을 시험(試驗)하였던 바 다음과 같은 결과(結果)를 얻었다. 1. 수분함량(水分含量)은 11시(時)부터 15시(時)까지 급격(急激)히 떨어졌으며 실내(室內)에서 17시(時)가지의 감량(減量)은 실외(室外)에서 1사간(時間) 동안의 감량(減量)과 같다. 2. OED green 처리(處理)와 무처리간(無處理間)에는 함수량(含水量) 변도(變動)에 큰 차이(差異)가 없었다. 3. 삼나무, 편백나무, 실생묘(實生苗)의 실(室) 및 주간건조(晝間乾燥) 조건(條件)에 있어서의 활착률(活着率)은 OEDgreen 처리(處理)나 무처리(無處理)가 각각(各各) 고도(高度)의 유의성(有意性)이 있었고 침적효과(浸積效果)도 미약(微弱)했다. 4. 편백나무묘(苗)의 활착률(活着率)은 삼나무 실생묘(實生苗)와 거의 일치(一致)하였으나 건조(乾燥)에 대(對)한 저항력(抵抗力)은 낮은 편(便)이다. 5. 삼나무 삽목묘(揷木苗)고 실생묘(實生苗)에 비(比)하여 활착률(活着率)이 높았으며 2시간(時間) 동안 건조(乾燥)한 경우(境遇)도 전(全)혀 활착률(活着率)에 영향(影響)이 없었다. 또한 건조시간(乾燥時間)과 침적시간(浸積時間)과의 상호작용(相互作用)에 고도(高度)의 유의성(有意性)이 있었다. 6.삼나무, 편백나무, 실생묘(實生苗)는 실내(室內)에서 4일간(日間) 건조(乾燥)하였을 때 2시경(時頃)부터 활착률(活着率)이 현저(顯著)히 떨어졌으며 건조일수간(乾燥日數間)에 고도(高度)의 유의성(有意性)이 있었다.

• 한국건축시공학회지
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• 제20권5호
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• pp.391-397
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• 2020

본 연구는 콘크리트산업 부산물인 회수수의 안정적인 재활용과 경량골재 콘크리트의 활성화를 위한 연구의 일환으로 회수수를 인공경량골재의 프리웨팅수 및 배합수로 적용한 경량골재 모르타르의 특성을 비교·분석하였다. 연구결과 프리웨팅수 및 배합수내의 회수수 농도 5%인 RW5 배합의 압축강도가 약 45.2~53.9MPa 수준으로 모든 재령에서 가장 높은 압축강도를 발현하였다. 인장강도의 경우 회수수 농도에 관계없이 재령 28일에 약 3.4~3.8MPa를 발현하여 압축강도 값의 7~9% 수준으로 나타났으며, 건조수축의 경우 RW2.5배합에서 재령 56일에 약 0.107%로서 가장 낮은 수축률을 나타내었다. 또한 촉진중성화 시험 결과 RW5 배합에서 약 1.75mm로 다른 배합에 비해 낮은 촉진 중성화 깊이를 나타내어 본 연구 대상인 경량골재 모르타르의 경우 회수수 농도 5% 수준에서 우수한 압축강도특성과 중성화 저항성을 나타내었다.

• 설비공학논문집
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• 제16권5호
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• pp.430-437
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• 2004

This paper is intended as an investigation of study on the thermal and electrical characteristics of the carbon heating element. In this experimentation, the electric material used is the crystalline graphite a kind of natural graphite. The bentonite is used to solidify the heating element and the vacuum furnace is used for sintering it. It is noted that the natural drying time should be at least 58 hours. The plating of the electric pole with the electroless nickel showed the lowest contact resistance among others. The resistance shows linear variation with regard to length. For the insulation and resolution, the glaze coating is best with 80% of water content. The temperature rising characteristic of the heating element is better than sheath heater saving 43% of rising time. The correlation equation for temperature was obtained with the electric power.

• 한국미생물·생명공학회지
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• 제24권4호
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• pp.393-398
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• 1996

In order to develop a lactic acid bacterial powder which can be used as a probiotic for human and animal, a lactic acid bacteria which has high resistance against low pH and ox-gall, and shows a good growth inhibition against E. coli, was isolated from an animal intestine and characterized. The isolated strain was identified as Enterococcus faecium. It had more than 90% of survival at low pH for 2 hours and almost 100% of survival in the presence of 0.3% ox-gall. When co-cultured with E. coli in MRS broth, all of the E. coli cells were killed within 24 hours. The final powdered product of the isolated strain was manufactured after a freeze drying process using an industrial media, and then checked its stability. Its storage stability was 80% for 11 months at 18$\circ$C.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.818-821
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• 2004

Generally, the high performance concrete of drying cracking and autogenous shrinkage are tend to be increased. In the previous study, it was found that the using method in combination with expansive additive and shrinkage reducing agent was more effective than the separtely using method of that. This study is to investigated the durability of high performance concrete using expansive additive and shrinkage reducing agent. Test results showed that the high performance concrete using expansive additive and shrinkage reducing agent had very good not only the durability performance such as salt injury, carbonation, resistance to freezing-thawing and permeability but also the resistance to shrinkage.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계 학술발표회 논문집(II)
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• pp.169-172
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• 2006

The IIA structures exposed to marine environment is subject to many different types of potential attack. The physical attack due to drying and wetting would increase the internal stress of concrete. The chemical attack resulting from the diffusion of ions$(Cl^-,SO_4^{2-},Mg^+)$ from seawater through the pores in concrete. Therefore the sea water resistance of concrete must be considered when it is used for structure in the ocean. The objective of this study is to evaluate chloride diffusion and corrosion characteristics of concrete when using the various concrete materials under marine environment. After 5 years of exposure, concrete incorporating 40% blast-furnace slag as replacement for type I cement with low w/c ratio of 0.42 and using the inhibitor shows excellent performance.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제51권12호
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• pp.601-607
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• 2002

IPMC(Ionic Polymer Metal Composite)actuators were optimized for producing improved forces by changing multiple parameters including repetition of number of plating, surface electroding and additive(PVP)-treatment on reduction. The platinum electrode is deposited on the surface of the material where platinum particle stay in a dense form that appears to introduce a significant level of surface electrode resistance. Actuation tests were performed for such IPMC actuators under a low voltage. The test results show that the lower surface-electrode resistance generates higher actuation capability in the IPMC actuators. In order to investigate relaxation behavior of bending and repeatability in dry condition, the IPMC was coated by$rubber(KRATON^{TM})$to minimize the effect of water evaporation from IPMC. This actuator can be used in air with surface coating to avoid membrane drying.

• International Journal of Concrete Structures and Materials
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• 제2권2호
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• pp.99-105
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• 2008

Southern exposure test specimens were used to evaluate corrosion performance of epoxy-coated reinforcing bars in chloride contaminated concrete by electrochemical impedance spectroscopy method. The test specimens with conventional bars, epoxy-coated bars and corrosion inhibitors were subjected 48 weekly cycles of ponding with sodium chloride solution and drying. The polarization resistance obtained from the Nyquist plot was the key parameter to characterize the degree of reinforcement corrosion. The impedance spectra of specimens with epoxy-coated bars are mainly governed by the arc of the interfacial film and the resistance against the charge transfer through the coating is an order of magnitude higher than that of the reference steel bars. Test results show good performance of epoxy-coated bars, although the coatings had holes simulating partial damage, and the effectiveness of corrosion-inhibiting additives. The corrosion rate obtained from the impedance spectroscopy method is equivalent to those determined by the linear polarization method for estimating the rate of corrosion of reinforcing steel in concrete structures.