• Journal of the Society of Disaster Information
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• v.8 no.4
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• pp.391-400
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• 2012

Recently, the construction industry commonly uses FRP as a reinforcement material because of its material advantages. FRP attached reinforcement has various advantages such as high strength, stiffness, excellent durability and construction practicability comparing to its weight. However, external attachment of FRP is water-tighted with low water permeable material, not draining water, probably causing damages on a permanent structure. The study manufactured it through pultrusion and examined GP(glass fiber panel) of which material-mechanical properties are almost same as the existing FRP but durability and attachment performance are better by stationary experiments, testing load-deflection curve, destruction types and load-deflection relation under repetitive loading test. As a result of 2,000,000 fatigue tests, it did not result in the destruction and showed excellent permanent attachment and durability as it displays significantly low compressive strain of concrete.

• Journal of the Korean Society for Railway
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• v.13 no.4
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• pp.389-395
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• 2010

This paper is about the copper slider with high electric conductivity and resistance arc. A new copper slider which has enhanced resistance against frictional wear was developed. By alteration of its material components and manufacturing process, its material property has been enhanced. To verify its enhanced wear-resisting capacity, a laboratory test and a field test were carried out. As the laboratory test, a dynamo test was performed and its test result showed that the developed new copper slider had superior wear-resisting capacity to the currently used copper slider. The new one showed double durability of the current one and normal wearing characteristics. A filed test was performed on the Metro subway lines at service by Seoul Metro. The field test showed similar results to those from the laboratory test, which the d eveloped new copper slider has double superior durability and sound wearing patterns. Authors strongly believe that the replacement of the copper slider currently in use by the developed new one will contribute to the economic and efficient operation of the subway line system

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.1
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• pp.56-63
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• 2016

This experiment was compared and analyzed between the original surface paint through chloride penetration, neutralization, freeze-thaw and chemical corrosion resistance measuring internal structure and volume of voids in order to evaluate the effect of increase in durability of the newly modeled nano synthesized polymer paint painted on concrete surface which results improvement on air permeability to increase the durability of concrete structures. The test result of measuring volume of void and inner structure, concrete, spreaded with nano synthesized polymer paint, showed decreasing trend of pore volume in the range of less than $0.1{\mu}m$ and more than $0.3{\mu}m$. Also, using an electron microscope inside showed tightness of hydration texture. Chloride penetration depth of concrete, painted with nano synthesized polymer paint, was decreased more than 92% compared to non-painted concrete and 70% with water-based epoxy painted concrete. Especially, chemical corrosion resistance test set with aqueous solution of 5% sulfuric acid, non-painted concrete and water-based epoxy painted concrete showed weight loss of 4% after dipping for 12 days. On the other hand, concrete painted with nano synthesized polymer paint showed 1.7% weight loss under the same condition. Also, it showed great result of appearance under the criteria of Tsivilis et al.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.487-490
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• 2005

In this study, for the establishment of the performance evaluation methods and the quality control standards of durability recovery method, the data of indoor durability test and the data of the long term exposure test under the coast are accumulated and analyzed. As a result of the indoor test, durability of repair material was more superior to that of plain concrete, but as a result of investigating and evaluating exposure test at 30 month of exposure age under the coastal environment, the difference in electric potential and the reinforcement corrosion at place replaced with repair material are found.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.279-280
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• 2009

This study is to aim an evaluation of concrete durability exposed to coastal circumstance. Therefore, six cores of the seawater pump were obtained by drilling, and their total chloride content were tested to predict initial time of steel corrosion..

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.11a
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• pp.320-320
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• 2015

표면개질이란 재료 본연의 특성만으로 원하는 성능과 기능을 발휘할 수 없을 때 기재 표면에 열에너지, 응력 등을 부가하여 새로운 표면층을 형성하는 방법이다. 특히 양극산화 기술을 이용해 형성된 피막은 경도 및 내마모성 등 기계적 성질이 우수하고, 공정조건 등을 변화시켜 피막 두께와 형상 조절이 용이하여 센서, 필터, 광학용 박막 그리고 전해콘덴서 등에도 주로 사용되고 있다. 본 연구에서는 5083 알루미늄 합금을 이용해 해양환경에서 우수한 내구성을 보유할 수 있는 최적의 양극산화 공정시간을 선정하고자 캐비테이션 실험을 실시하였다. 실험 결과, 공정시간 40분에서 안정적인 산화피막 생성과 함께 탁월한 내캐비테이션 특성을 나타냈다.

• The Journal of Natural Sciences
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• v.8 no.2
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• pp.191-198
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• 1996

We were investigated the change of shrinkage, pilling, tensile strength, color fastness and staining of Cotton, Nylon, Cotton/Nylon(60/40) socks after wearing and washing. From the experiment we found that color fastness of the color socks decreased corresponding to the frequency of wearing and washing. Our results showed that color fastness in the case of Cotton is best among them. Shrinkage was significant in Nylon/Cotton and Cotton socks. In the experiment of male and female socks, male showed a greater evidence of staining, shrinkage and pilling than female.

• Journal of the Korea Concrete Institute
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• v.26 no.5
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• pp.607-614
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• 2014

The purpose of this dissertation was to investigate the effect of mineral admixtures, such as fly ash, blast furnace slag powder, meta kaolin and silica fume, on the basic properties and durability of crushed sand shotcrete, selecting a series of shotcrete mixtures with a variable admixture. Compressive strength increased as the content of mineral admixtures increased, specially it was the most effective when using meta kaolin both at sample specimen and core after shotcreting. Rapid chloride ion permeability test and sulfuric acid resistance test showed that both durability increased as the substitute rate of mineral admixture increased. In air void analysis with image analysis, the targeted the spacing factor and specific surface were not satisfied because air-entrained agent was not used.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.467-468
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• 2010

Over the past few decades, considerable numbers of studies on the durability of concrete have been carried out extensively. The majority of these researches have been performed on sound uncracked concrete, although most of in-situ concrete structures have more or less micro-cracks. It is only recent approach that the attention has shifted towards the influence of cracks and crack width on the penetration of chloride into concrete. The penetration of chlorides into concrete through the cracks can make a significant harmful effect on reinforcement corrosion. Author of this study examined the effect of cracks on chloride penetration by short term experiment. However, it is necessary to accomplish the effect by long term experiment to get reliable goal. In this study, the long term and short term experiments were carried out. This can be useful for establishing new species model of chloride penetration through cracks in concrete.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.3
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• pp.75-83
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• 2012

Porosity in concrete has close relationship with durability characteristics. Additionally mixed water can help easy mixing and workability but causes increased porosity, which yields degradation of durability performance. In this paper, cement mortar samples with 0.45 of w/c (water to cement ratio) are prepared and durability performances are evaluated with additional water from 0.45 to 0.60 of w/c. Various durability tests including strength, chloride diffusion, air permeability, saturation, and moisture diffusion are performed. Then they are analyzed with changing porosity. Changing ratios and the patterns of durability performance are quantitatively evaluated considering pore size distribution, total porosity, and additional water content.