• Title/Summary/Keyword: 조기 강도

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Fabrication of the micro-mold and nanofiber using cellulose solution (셀룰로오스를 이용한 마이크로 몰드 및 나노섬유 제작)

  • Cho, Ki-Youn;Lim, Hyun-Kyu;Kang, Kwang-Sun;Kim, Jae-Hwan
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2007.11a
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    • pp.69-72
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    • 2007
  • Cellulose is a beneficial material that has low cost, lightweight, high compatibility and biodegradability. Recently electroactive paper (EAPap) on cellulose base was discovered as a smart material and actuator through ion migration and piezoelectric effect. Furthermore cellulose has a potentiality to apply the display material, because of its high reflectivity, flexibility and high transmittance. The various shapes and height patterns of the Cellulose acetate (CA) solution, such as circle and honeycomb patterns, were fabricated and observed by field emission scanning electron microscope (FESEM, S4300 Hitachi). The resulting pattern showed uniform size in the large area without defect. After stretching the CA film with saponification process in the sodium methoxide in methanol solution, Most of the compositions become one directional ordered nanofibers below 50nm.

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Experimental Estimation of the Early Strength of Belite Cement Mortar Using Microwave (저열 포틀랜드(4종)시멘트 모르터의 마이크로파를 이용한 조기강도 추정에 관한 실험적 연구)

  • 김민석;박재한;정근호;이종균;이영도;정상진
    • Proceedings of the Korea Concrete Institute Conference
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    • 2001.11a
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    • pp.1077-1082
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    • 2001
  • The most recent building trend is going large, high rise, high strength as overlarge project is developing in domestic construction business. Belite cement has properties like low heat, excellent long term strength, and durability without admixture(fly ash, silica fume). so, Belite cement is suitable for mass structure which is needed high strength, high fluidity and low heat property. This study is to examine the possibility of site adoption microwave-use early strength estimation method. Based on the existed study related the portland cement, the interrelation between Belite cement and microwave-use early strength estimation method is required. In this study, interrelation between mortar and Evaluating strength estimation method is investigated before the concrete experiment.

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An Experimental Study on the Early Prediction of Concrete Strength by Accelerating Agent (급속경화에 의한 콘크리트 강도의 조기 판정에 관한 실험적 연구)

  • 김창교;최창식;이리형
    • Proceedings of the Korea Concrete Institute Conference
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    • 1989.10a
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    • pp.9-13
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    • 1989
  • The purpose of this paper is to propose a method predetermining the 28-days strength of concrete. In this paper, it was predicted by regression analysis of the relation between 7-days and 28-days strength of fresh concrete and the strength of concrete early cured at $70^{\circ}C$ for rour hours after wet screening and addition of accelerating agent. It is concluded that the formula predeterming the 28-days strength of concrete using 25M/M rubbles from Sam-Cheok and sands from Yon-Gok, by the strength of concrete early cured for 4 hours is Y=-11.45 + 3.686X, where the coefficient of determination of regression-expression is r2=0.938, S=17.94(kg/$\textrm{cm}^2$).

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A Site Application of the Revealing High Early Strength Concrete (조기강도 발현형 콘크리트의 현장 적용성 연구)

  • Kim Gyu Dong;Lee Seung Hoon;Sohn Yu Shin;Kim Han Joon
    • Proceedings of the Korea Concrete Institute Conference
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    • 2004.05a
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    • pp.560-563
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    • 2004
  • This study reports the site application of concrete using AE Water Reducing Agent of Early-Strength Type. According to the lab test results, we have made plans of batch plant pilot test, and we have analyzed the erly aged compressive strength and workability of the concrete. We applied the early-strength development concrete to the construction site. We accomplished the slump test in order to evaluate the workablity and air contents, we made site curing mold to evaluate the early strength of members. As a result, we judgeed the superior property of early strength development of the concrete, and thought that we can reduce the time of form stripping more $40\%$ than ordinary strength concrete. We thought that we can reduce the term of works and finally we can accomplish the economical construction.

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A Study on the Measurement of In-plane Deformations by using Electronic Speckle Pattern Interferometry and Finite Element Method (전자 스페클 간섭법과 유한요소법을 이용한 면내변형의 측정에 관한 연구)

  • Kang, Hyung-Soo;Cho, Ki-Hyon;Kim, Hong-suk;chung, Hyung-kil
    • Journal of the Korean Society of Industry Convergence
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    • v.5 no.3
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    • pp.187-192
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    • 2002
  • In-plane ESPI(Electronic Speckle Patten Interferometry)was devised to measure in~plane defamation and rotation of a specimen with laser in this study. The conventional measuring methods of surface deformations such as the strain gauge have many demerits because they are contact and point-to-point measuring ones. But that ESPI is noncontact, nondestructive and whole field measuring method can overcome previous disadvantages. We used ESPI which is sensitive to in-plane displacement for measuring in-plane deformations of a disk. First of all, the system calibration was done due to an in-plane rotation before getting deformations of a disk. Finally we showed good agreement between theexperiment results and those of the FEA(Finit Element Analysis).

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분자세포유전학적 기법을 이용한 Freematin의 진단

  • 강민영;전혜정;손시환
    • Proceedings of the KSAR Conference
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    • 2003.06a
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    • pp.23-23
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    • 2003
  • 프리마틴(freemartin)이라 함은 반추동물들 중 특히 소에서 나타나는 간성(intersex)형태로 이성 쌍자의 경우 태어난 암컷의 대부분이 정상적인 자성 생식기의 발육 및 발생양상을 지니지 못하여 생식불능상태로 되는 것으로 알려져 있다. 최근 실용화된 수정란이식이나 쌍자유기 등의 기술은 현재 일반 농가에 까지 정책적으로 확대 보급되어 산업화되고 있는 실정이나 불행히도 이러한 기술들을 이용하여 생산된 개체들 중 상당수가 이성쌍자로 이들 중 암컷 개체들은 거의 freemartin으로 생산되어 실지 노력에 비해 경제적 효과들을 크게 반감시키고 있다. 뿐만 아니라 생산된 freemartin 개체들에 대하여 조기 진단 없이 다만 형태적으로 암컷으로 판단하여 번식우로 사양관리 함에 따른 경제적 손실이 매우 크다 할 수 있겠다.

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The Comparison of the Environment Consciousness and the Disposal Behavior Between the Urban Children and the Rural Children (아동의 환경의식과 처분행동에 관한연구 -도시와 농촌간의 비교연구-)

  • 강이주
    • Journal of Families and Better Life
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    • v.13 no.2
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    • pp.35-44
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    • 1995
  • 본연구의 목적은 아동의 환경의식과 처분행동을 조사하여 환경문제에 대한 아동의 역할을 조명하고 조기환경교육의 기초자료를 제공하는데 있다 조사도구는 질문지를 이용하 였고 분석방법은 SAS통계프로그램을 이용하였다 환경의시과 처분행동의 차이는 ANOVA와 Tukey test를 지역간(도시, 농촌)의 차이는 t-test 와 $\chi$2 검정을 사용하였다 분석에 이용된 자료는 도시 311부 농촌 299부로 총 610부였다 본연구의 결과를 요약하면 다음과 같다 1) 도시와 농촌간의 환경의식은 통계적으로 유의한 차이가 없이 모두 높게 나타났다 2) 인구통 계변수에 따른 환경의식은 생활수준과어머니의 교육수준이 높을수록 높았으며 주거형태별로 는 아파트 거주자가 높게 나타났다 3) 도시와 농촌간의 처분행동은 유의적인 차이를 보였는 데 도시 지역이 높게 나타났다 4) 인구통계변수에 따른 처분행동은 환경의식과 마찬가지로 소득과 어머니의 교육수준이 높을수록 높았으며 아파트 거주자와 종교가 있느 아동이 높게 나타났다 이러한 결과는 환경을 고려하는 행동양식의선행변수가 교육임을 재확인해주었다

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Application of High Durable Concrete in Post-Tensioned Concrete Pavement (포스트텐션 콘크리트 포장에서 고내구성 콘크리트의 적용)

  • Choi, Pan-Gil;Lee, Bong-Hak;Jeong, Beom-Seok;Kim, Dong-Ho
    • Proceedings of the Korea Concrete Institute Conference
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    • 2009.05a
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    • pp.435-436
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    • 2009
  • The objective of this study was to develop the high-durable concrete which is mixed silica fume and fly ash in post-tensioned concrete pavement. Test results show that early-age compressive strength was increased with addition of silica fume. Water-permeability was improved significantly comparing with standard concrete.

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The Effect of Boshimdan(補心丹:$\breve{b}ux\bar{i}nd\bar{a}n$) on Ischemic Heart Disease (허혈성(虛血性) 심근(心筋)에 보심단(補心丹)이 미치는 영향(影響))

  • Gang, Myeong-Seok;Go, Chang-Nam;Jo, Gi-Ho;Kim, Yeong-Seok;Bae, Hyeong-Seop;Lee, Gyeong-Seop
    • The Journal of Internal Korean Medicine
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    • v.16 no.2
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    • pp.61-73
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    • 1995
  • In this study, the effects of Boshimdan, which is used in oriental medicine for the treatment of palpitation, chest discomfort, impatience, insomnia, forgetfulness ete., were tested as a part of series of experimental verification of prescriptions treatments for preventing and curing ischemic heart. The results were as follows: 1. Boshimdan did not effectively work on heart rate of the perfused rat heart. 2. Boshimdan did not effectively work on heart pressure of the perfused rat heart. 3. Boshimdan did not effectively work on flow rate of the perfused rat heart. 4. Boshimdan was not effective in activation of GOT. 5. Boshimdan was not effective in activation of GPT. 6. Boshimdan was not effective in activation of LDH. 7. Boshimdan was not effective in activation of CPK.

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An Experimental Study on the Early Estimation of Recycled Aggregate Concrete Strength by Using Microwave (마이크로파를 이용한 재생골재 콘크리트 강도의 조기추정에 관한 실험적 연구)

  • 이민경;남정민;조규현;양동일;김성식;정상진
    • Proceedings of the Korea Concrete Institute Conference
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    • 2003.11a
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    • pp.569-572
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    • 2003
  • In many countries a considerable amount of demolition wastes is generated and wastes concrete constitutes a significant proportion of the construction waste. Therefore, the necessity for the use of recycled aggregate in concrete arise and the reuse of a waste concrete may solve the problems of environmental pollution and shortage of natural aggregate. According to this study is to examine the possibility of site adoption microwave-use early strength estimation method. Based on the existed study related the plain concrete, the interrelation between recycled aggregate concrte and microwave-use early strength estimation method is required.

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