• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.1
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• pp.101-110
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• 2014

Expansion agent is a very effective admixture for prevention of cracking due to autogenous/drying shrinkage and this can induce internal chemical prestress to embedded reinforcement. In this paper, tension-softening and hardening in cement mortar with steel and CSA expansion agent are experimentally evaluated. Cement mortar with steel reinforcement is prepared and tensile strength test is performed for evaluation of cracking and tensile behavior. In spite of slightly reduced strength and elasticity in CSA mortar, significantly increased tension-hardening behavior is evaluated in CSA mortar with induced chemical prestress. Furthermore previous tension softening models are compared with the test results and improvement are proposed.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.31 no.1
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• pp.53-61
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• 2018

Ballast track requires constant maintenance work due to progress of track irregularity. Fast Hardening Track(FHT) has been developed to reduce the maintenance effort done by injecting fast hardening mortar in aged ballast to convert slab track. For the application of FHT to a railway bridge, post-installed anchors should be placed at center of the track segment to fix it on bridge. This paper presents track-bridge interaction analysis results with FHT considering stiffness and strength of post-installed anchor, age of FHT concrete and friction between FHT and bridge deck surface. Based on the analysis results, this study suggests when is good to install the anchors and allow normal operation of passing train.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.4
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• pp.121-128
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• 2007

The present study evaluates the resistance to sulfate attack of cement matrix with or without silica fume. The main variable was the replacement levels of silica fume. In order to introduce sulfate attack to cement matrix, mortars and pastes was exposed to sodium sulfate solution for 510 days. Visual examination, expansion and compressive strength loss of mortars in addition to characteristics of pore for the paste samples were regularly investigated. From the test results, it was clearly observed that the cement matrix with silica fume was very resistant to sulfate attack irrespective of the replacement levels of silica fume. However, the severe deterioration due to sulfate attack was found in cement matrix without silica fume.

• Proceedings of the Korean Society of Applied Pharmacology
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• 2001.04a
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• pp.45-59
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• 2001

최근 급속한 산업화와 경제발전으로 인해 소득수준이 향상되면서, 고단백질 및 고지방질 식품의 섭취 및 운동부족으로 인한 성인병, 특히 비만증, 고지혈증, 당뇨병 및 심장순환기계질환이 급속히 증가되어 사회문제로 대두되었고, 한국을 포함한 선진각국의 고지혈증 및 심장순환기계질환의 발병빈도가 여전히 증가추세에 있다. 보건위생의 여건이 좋아지면서 전염성질환이 줄어들었으나, 심장 순환기 질환의 발병률은 계속 증가추세에 있고, 순환기질환은 고지혈증에 의하여 발병되며 이 질환의 사망률은 전체 사망률 중 상위를 차지하고 있다. 인간은 고지혈증에 의한 동맥경화로 인한 사망률은 전체 사망률 중에서 상위를 차지하고 있으며, 그에 따른 의약품의 개발이 요구되고 있고, 현재 임상적으로 사용되고 있는 고지혈증 치료제로는 체내의 cholesterol 생합성 저해제가 있으나, 보다 제한사항이 없고, 작용기작이 확실하며 부작용이 적은 새로운 고치혈증 치료제의 개발이 요구되고 있다. 콜레스테롤은 세포막의 구성과 스테로이드 호르몬의 전구체로서 생체를 구성하는데 필수적인 요소이지만 과다하게 공급되었을 경우 동맥경화와 같은 심혈관계 질환을 유발할 수 있다. 체내에 콜레스테롤의 공급은 체외 음식물로부터 섭취하는 방법과 체내에서 생합성에 의해 공급되는 방법이 있는데, 서로 유기적인 보완관계를 유지하면서 필요한 콜레스테롤의 양을 유지한다. 그러나, 현대인의 식생활이 급격한 서구화로 체외로부터 필요량 이상으로 콜레스테롤이 유입되어 각종 성인병 발명의 상승 요인이 되고 있다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.1
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• pp.85-92
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• 2021

The purpose of this study is to investigate the properties of hardener-free epoxy-modified mortars(EMMs) using ground granulated blast furnace slag(GGBFS) and alkali activators. The hardener-free EMMs with a GGBFS content of 20% using 4 types of alkali activators were prepared with various polymer-binder ratios, and tested for strengths, water absorption, carbonation depth, chloride ion and H2SO4 penetration depth. The conclusions obtained from the test results are summarized as follows: The compressive strength of the EMMs with a GGBFS content of 20% attains a maximum at a polymer-binder ratio of 10%. The flexural strength of the hardener-free EMMs using Ca(OH)2 as a alkali activator is improved with increasing polymer-binder ratios. However, the flexural strength of the EMMs using NaCO3, Na2SO4 and Li2CO3 is gradually decreased with increasing polymer-binder ratios. Regardless of the type of alkali activator, the water absorption, chloride ion penetration and carbonation depth are remarkably decreased with increasing polymer-binder ratios due to the epoxy film formed in the EMMs. The H2SO4 penetration depth of the hardener-free EMMs with a GGBFS content of 20% is gradually increased with increasing polymer-binder ratio. In this study, the properties of hardener-free EMMs using Ca(OH)2 as a alkali activator are more excellent than those of other alkali activators.

• The Monthly Diabetes
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• s.156
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• pp.24-27
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• 2002

모든 인체의 조직과 장기는 혈액순환을 통해 산소와 영양을 공급받고 노폐물을 배출하여 정상적인 기능과 활동을 유지하고 있다. 특히 뇌의 크기가 1300g 정도로서 무게로는 전체의 2$\%$정도밖에 안되지만 혈류의 20$\%$정도를 공급받을 만큼 매우 중요한 기관으로, 뇌는 뇌혈관을 통하여 지속적으로 산소와 영양을 공급받아야 정상적인 활동을 할 수 있다. 노인에서 증가하고 있는 고혈압, 당뇨병 등과 같은 만성질환은 여러 장기의 혈관에 동맥경화증을 유발하며, 특히 뇌혈관에 동맥경화증이 생기게 되면 혈관이 막혀 뇌혈류가 차단되어 뇌경색증이 발생하거나 뇌혈관이 터지게 되어 뇌출혈이 발생하게 된다. 이러한 뇌혈관의 급격한 변화로 뇌조직의 손상으로 인한 갑작스러운 신경마비 증상이 나타나게 되는데 이러한 증상을 통틀어 뇌졸중 또는 중풍이라고 한다.

• 한국도로학회:학술대회논문집
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• 2005.03a
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• pp.137-146
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• 2005

• 한국도로학회:학술대회논문집
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• 2005.11a
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• pp.331-336
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• 2005

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.461-467
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• 2021

Among the defect factors that can occur when a wafer-level lens is molded using a thermosetting material, the mold sticking problem of a molded lens during the release process can damage the molded substrate and deform the substrate at the wafer level. An experiment was conducted to examine the factors affecting the demolding force in the lens forming process. The demolding force was examined according to the coating material of the molds. The mold was surface-treated with ITO and Ti, followed by plasma treatment in an O2 atmosphere. A DLC coating was then performed, and the curing and releasability were examined. A coating method for the pull-off experiment was selected based on the results. To measure the demolding force according to the curing process conditions, a method of curing at a constant pressure and a method of curing at a constant position were applied. As a result, the TiO2 surface treatment reduced the release force. When cured by controlling the location, curing shrinkage can reduce the adhesion energy of the interface during curing, resulting in better demolding.

• Elastomers and Composites
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• v.49 no.3
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• pp.210-219
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• 2014

In this study, the acrylic pressure sensitive adhesive (PSA) for the optical functionality sheet was prepared by blending liquid isoprene rubber. The acrylic PSA was synthesized with butyl acrylate, acrylic acid, 2-ethylhexyl acrylate and 2-hydroxyethyl methacrylate. Toluene was used to a solvent for polymerization. Liquid isoprene rubber (LIR-50) was blended with the acrylic PSA and blend ratio was 0 ~ 50 wt%. According to the results, the adhesive transfer, which was the big problem of acrylic adhesive, was reduced with the addition of LIR-50. The secondary bonding of LIR-50 with substrate did not occurred due to absence of polar group in LIR-50. The peel strength and adhesive transfer were decreased by UV curing and the degreed of decrease depended on the amounts of photoinitiator and UV irradiation time. On the other hand holding power increased drastically by increasing amounts of photoinitiator and UV irradiation time.