• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2001.10a
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• pp.119-122
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• 2001

Annual demand of a precast concrete bench flume used in the irrigation canal of arable land readjustment has continuously increased units recently. The average life time of the precast concrete bench flume was estimated $8{\sim}10$ years, which is too shorter than the life time of in-site placed concrete structures. In order to increase the compressive strength of the precast concrete bench flumes, the highest temperature of being lower than $95^{\circ}C$ was suggested in this study, Through analyzing the relation between the compressive strength and the amount of chloride penetration into concrete specimens, a new formula early estimating durability of the concrete structure was suggested.

• TTA Journal
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• s.144
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• pp.18-19
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• 2012

최근 지식경제부 산하 산업기술연구회가 앞으로 10년간 한국을 먹여 살릴 최고 수준의 기술 14가지를 발표했다. 산업기술연구회 산하 7개 출연연구기관은 지난해부터 매년 '세계 1등 연구과제'를 지정받아 세계 최고 수준의 성과를 내놓고 있다. 이 가운데 세계 1위를 달리고 있는 기술은 한국생산기술연구원의 '에코 알루미늄 에코 마그네슘'과 '해조류 셀룰로오스 등을 이용한 연료 생산 기술', 한국전자통신연구원의 '100배 빠른 광인터넷 기술', 한국건설기술연구원의 '세상에서 가장 긴 콘크리트 교량 기술', 한국철도기술연구원의 '콘크리트 발열 촉진 양생 기술'을 비롯해 '저심도 도시철도 시스템 기술'과 초경량 유리섬유 복합소재 전동차 대차 프레임', 한국화학연구원의 '하이브리드 나노세공체 응용 연구' 등 8가지이다. 이 중 몇 가지 기술을 살펴보자.

• Journal of Korean Medical classics
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• v.20 no.1
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• pp.125-136
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• 2007

본연구장이송대이후유의적성립화의이투과명대적대표적유의장개빈(本硏究將以宋代以後儒醫的成立和意而透過明代的代表的儒醫張介賓), 진행검시의론화의덕지중유학이론적투영과정화전개(進行檢詩醫論和醫德之中儒學理論的投影過程和展開). 송대이후유학적인산생유의적지중칭지위인술적개념(宋代以後儒學的仁産生儒醫的之中稱之爲仁術的槪念), 효화인성위의학적존립목적(孝和仁成爲醫學的存立目的). 저래원재어유학구유적도덕적생명의(這來源在於儒學具有的道德的生命議), 이차이생명도덕적해석위중심(而且以生命道德的解釋爲中心), 해석형기적문제(解釋形氣的問題). 생리적변화촉진심성변화적촉발(生理的變化促進心性變化的觸發), 심성적부중절조성병리(心性的不中節造成病理). 유의문장유학적절욕양생적의미전이도의학(儒醫們將儒學的節欲養生的意味轉移到醫學), 이차장욕구화감정절제주장적성리학화의학재어일개구조지중상통(而且將欲求和感情節制主張的性理學和醫學在於一個構造之中相通). 유학적추구시인간화자연이급사회적도덕주체적확립(儒學的追求是人間和自然以及社會的道德主體的確立), 이차전개장개빈이급유의문적유학이상(而且展開張介賓以及儒醫們的儒學理想). 유의적의의부지재어장의학적과학기술문제(儒醫的意義不只在於將醫學的科學技術問題), 장유추인간생명적도덕적의의(將類推人間生命的道德的意義), 재어의학적문화화도덕적해석적가능성(在於醫學的文化和道德的解釋的可能性).

• Tunnel and Underground Space
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• v.32 no.6
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• pp.363-372
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• 2022

Precast concrete is an effective method to increase the construction quality and construction speed by optimizing and making the manufacturing conditions similar. In order to more effectively produce a fireproof material-integrated precast duct slab, the purpose of this study was to determine whether the fire resistance performance of the fireproof layer is maintained when a method of increasing the curing rate using a hardening accelerator is used. As a result of performing a fire resistance performance test on specimens classified according to whether or not the hardening accelerator was included, increase of temperature inside the specimen was high in the specimens using the hardening accelerator, and the section loss of the fireproof layer occurred locally on the surface exposed to fire heating. In conclusion, it is judged that the fireproof layer in the case where the strength at 3th day of age is gained within 1 day curing age using a hardening accelerator does not guarantee sufficient fire resistance performance in the conditions used in this study.

• Journal of the Korea Concrete Institute
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• v.16 no.1 s.79
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• pp.54-60
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• 2004

This study deals with the setting behavior of polystyrene mortars using waste expanded polystyrene(EPS) solution-based binders. The binders for polystyrene mortars are made by mixing crosslinking agent with EPS solutions prepared by dissolving EPS in styrene. Polystyrene mortars are prepared with various EPS concentrations of EPS solutions and crosslinking agent contents, subjected to a dry curing, and tested for working life, peak exotherm temperature and 10h-length change. From the test results, He working lives of polystyrene mortars are shortened with raising EPS concentration of EPS solution and crosslinking agent content. Low-shrinkage or non-shrinkage polystyrene mortars could be obtained by adjusting EPS concentration of EPS solution and crosslinking agent content.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.6
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• pp.83-90
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• 2017

Concrete structure for nuclear power plant is mass concrete structure with large wall depth and easily permits cracking in early age due to hydration heat and drying shrinkage. It always needs cooling water so that usually located near to sea shore. The crack on concrete surface permits rapid chloride intrusion and also causes more rapid corrosion in the steel. In the study, the effect of age and crack width on chloride diffusion is evaluated for the concrete for nuclear power plant with 6000 psi strength. For the work, various crack widths with 0.0~1.4 mm are induced and accelerated diffusion test is performed for concrete with 56 days, 180days, and 365 days. With increasing crack width over 1.0mm, diffusion coefficient is enlarged to 2.7~3.1 times and significant reduction of diffusion is evaluated due to age effect. Furthermore, apparent diffusion coefficient and surface chloride content are evaluated for the concrete with various crack width exposed to atmospheric zone with salt spraying at the age of 180 days. The results are also analyzed with those from accelerated diffusion test.

• Journal of the Korea Institute of Building Construction
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• v.16 no.5
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• pp.405-412
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• 2016

In order to examine the possibility of practical use of concrete at low-temperature environment using high early strength cement with cold resistance admixture, an experimental study on workability, freezing temperature and compressive strength of the mortar with different types of anti-freezer, water reducing agent and accelerator for freeze protection at low-temperature were evaluated. Compressive strength was increased in use of anti-freezer, especially SN anti-freezer was higher than CN anti-freezer. 0min flow was increased, the 20min flow was decreased. And 20min flow was improved in use of FR, RT water reducing agent. CF, LS accelerator for freeze protection, regardless of the type of water reducing agent, compressive strength was increased.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.5
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• pp.21-29
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• 2017

Cold joint caused by construction delay is vulnerable to shear stress and it allows more rapid chloride penetration and diffusion. In the paper, investigation of chloride diffusion coefficient is performed for 1-year cured concrete considering compressive and tensile loading level and cold joint. The results are compared with the previous results in 91-day cured concrete. In the 1-year cured concrete without loading, 10.7% and 10.5% of diffusion reduction are evaluated for those in 91-day cured concrete, respectively. The reduction ratios are almost similar however the result in cold joint concrete shows much higher values. The results in 1-year cured concrete under 30% and 60% of compressive loading show reduction of chloride diffusion by 10.9% and 5.8% compared with 91-day cured results, which is caused by steady hydration of cement particles, so called, time effect. In the case of tensile loading, the differences in results are not significant regardless of time effect and cold joint since micro cracks which is weak point of concrete is much dominant despite of long term curing.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.4
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• pp.418-424
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• 2016

This study is an experimental study on the recycling of bottom ash in coal ash discharged from a thermal power plant. Bottom ash has limited research on recycling because it has more porous and higher water absorption ratio than fly ash. In this paper, the bottom ash was pulverized to a specific surface area of $4,000cm^2/g$ in order to use as a binder, and the flow, compressive strength test and microstructure analysis of the bottom ash based geopolymer mortar were performed. The flow measurement results of the geopolymer mortar showed that the flow rate was improved by increasing mixing water as the molar concentration of activator was increased. Compressive strength increased with increasing curing temperature and molar concentration. Through the microstructure analysis, we could confirm the geopolymer gel produced by the reaction of the condensation polymerization. It is considered that it is possible to make the bottom ash based geopolymer concrete through proper molar concentration of activator and high temperature curing.

• Journal of the Korea Institute of Building Construction
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• v.18 no.3
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• pp.203-210
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• 2018

Corrosion of the rebar is one of the main factors affecting the durability of reinforced concrete in the world which lead to the failure of the reinforced concrete structures. In this research, a new method of fixing $CO_2$ is practiced to improve the carbonation resistance of the concrete. Brucite($Mg(OH)_2$), a kind of common $CO_2$ fixation materials, was added into ordinary Portland cement paste. Samples containing 0%, 5%, 10%, and 15% $Mg(OH)_2$ were exposed to an accelerated carbonation curing regime with 20% concentration of $CO_2$, 60% relative humidity, and a temperature of $20^{\circ}C$ until tested at 3d, 7d, 14d and 28d. After 28d of $CO_2$ accelerated curing, in the paste containing $Mg(OH)_2$, magnesian calcite was detected by SEM-EDX. Meanwhile, the paste containing $Mg(OH)_2$ exhibit the better pore distribution than ordinary Portland cement paste and the compressive strength of the cement paste containing $Mg(OH)_2$ were more than 50Mpa.