• 한국농공학회:학술대회논문집
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• 한국농공학회 1998년도 학술발표회 발표논문집
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• pp.161-166
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• 1998

This experiment was on purpose to estimate freezing and thawing resistance concering with developing rice straw ash concrete which were mixed rice straw ash to cement as ratio of cement weight. Freezing and thawing test was done by Method A of KS F 2456. It could estimate change of original mass, pulse velocity and dynamic modulus of elasticity during test. Test results showed that 5% filled rice straw ash concrete had the highest durability factor(DF) as 86 and from 5% to 7.5% filled rice straw ash concrete showed higher DF than normal cement concrete.

• 한국농공학회논문집
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• 제55권2호
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• pp.65-75
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• 2013

In this study, the engineering characteristics of volcanic ash-cement soil mixtures and zeolite-cement soil mixtures are investigated by using unconfined compression test, freezing-thawing test, SEM and XRD analysis. The samples were mixed with volcanic ash from Mt. Baekdusan or porous zeolite, and cement as the ratios of 3.5:1, 4.0:1, 4.5:1, 5.0:1 with and without metakaolin. It is confirmed that compressive strength degraded with increasing of the amount of volcanic ash or zeolite, and increased with addition of metakaolin as a binder. Moreover, test results suggested that the mixtures provided sufficient freezing-thawing resistance. In addition, ettringite as a product of cement hydration was detected by SEM and XRD, and that possibly contributes to the strength of the mixtures.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1993년도 가을 학술발표회 논문집
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• pp.65-70
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• 1993

The effect of particle size of Al powder, water repellent agent and finishing agent on frost resistance, absorption ratio and structure of micropore was examined to improve the physical properties and durability of ALC. According as the amount added of water repellent agent was increased, frost resistance was improved and absorption ratio was decreased. From one side freezing /thaw test, finishing agent which has a low vapor permeation located the crack at close indoor point of ALC specimen. ALC produced from fine Al powder has a low volume reduction by scalling and a sound appearance after freezing/thawing test and top surface freezing test, The crystal of tobermorite in ALC matrix was converted to calcium carbonate by carbonation which was accelerated with the decreasing of water content. Since the micropore of ALC was filled up by calcium carbonate, void ratio was reduced and crack was detected after complete carbonation.

• 대한수의학회지
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• 제59권1호
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• pp.43-45
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• 2019

To establish appropriate conditions for a disinfectant efficacy test at subzero temperatures, this study examined mixtures of frozen foot-and-mouth disease virus or avian influenza virus solutions and disinfectant diluents at $-5^{\circ}C$ and monitored temperature and freezing status of an anti-freezing diluent (AFD, 15% ethanol + 30% propylene glycol + 55% distilled water) over time at various subzero temperatures. Viral solutions and disinfectant diluents froze before the mixtures reached $-5^{\circ}C$, whereas the AFD was not frozen at $-30^{\circ}C$. The times taken for the AFD to reach -10, -20, -30, and $-40^{\circ}C$ from room temperature were 36, 39, 45, and 48 min, respectively.

• 한국도로학회논문집
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• 제14권3호
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• pp.25-32
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• 2012

현재 도로포장 설계법에 따르면, 동상방지층의 두께는 지역별 온도조건에 따라 결정되는 동결깊이에 의해 결정되며 동상방지층의 지지력은 설계에서 고려되지 않고 있다. 동상방지층을 도로포장체에서 구조층으로 고려할 경우에는 기존 도로포장층의 두께를 감소시킬 수 있으며 보다 경제적인 도로 포장단면을 구성할 수 있다. 본 연구에서는 동상방지층의 지지력을 평가하기 위한 통계적 모형을 개발하였다. 동상방지층의 구조적 역할을 규명하고 동상방지층 구조적 평가 모형 개발을 위하여 2m 이하 저성토부, 절토부 및 절성경계부 등을 구분하여 포장 하부층에서 Falling Weight Deflectormeter(FWD) 시험을 계절별로 수행하였다. 본 시험은 동방방지층의 유무에 따른 지지력 차이를 규명하기 위하여 동방방지층이 있는 구간과 없는 구간으로 구분하여 수행하였다. 본 시험결과, 동상방지층이 설치된 구간에서의 FWD 처짐량이 동상방지층 미설치 구간에 비해 0.4~82.6% 작게 측정되어 동상방지층이 포장체에서 지지력을 검증하였다. 다양한 FWD 처짐지수와 동상방지층 두께와의 상관관계를 조사한 결과, 보조기층 파손지수의 차이값(${\Delta}BDI$)과 동상방지층 두께와의 상관도가 가장 높았다. 본 논문에서는 ${\Delta}BDI$값을 선형혼합효과 모형에 적용하여 동상방지층을 구조적으로 평가할 수 있는 모형을 개발하였다.

• 한국지반신소재학회논문집
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• 제10권1호
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• pp.19-28
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• 2011

본 논문에서는 동결-융해 반복작용이 화강풍화토의 압축강도 특성에 미치는 영향에 관한 내용을 다루었다. 이를 위해 세립분 함유량을 변화시켜 다양한 시료조건을 조성한 후 동결-융해 시험 환경을 조성한 후 동결-융해 반복작용 사이클을 강제 부가하였다. 시료에 대한 평면변형률압축시험 및 미세입자구조의 변화를 가시적으로 확인할 수 있는 전자주사현미경(SEM) 촬영 및 분석을 수행하였다. 먼저, SEM 분석 결과 화강풍화토는 동결-융해 반복작용에 노출될 경우 입자들이 뭉쳐 간극이 증가하는 추세를 보였다. 한편, 압축강도 특성의 경우 세립분 함유량에 따라 다소 차이를 보이는 것으로 나타났는데 세립분 함유량이 적은 경우에는 강도저하 현상을, 세립분 함유량이 많은 경우에는 강도 증가 현상을 보임을 확인할 수 있었다.

• 한국지반공학회논문집
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• 제26권7호
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• pp.71-80
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• 2010

지리학적 특성으로 국내는 계절 동토지역으로 겨울철에는 동상현상이 발생하고 봄철에는 지반이 해빙된다. 도로는 다양한 재료와 단면으로 구성된 구조물이기 때문에 환경성과 재료 물성뿐만 아니라 포장체 각 층의 구조적 적정성 또는 지지력을 파악하는 것이 무엇보다 중요하다. 현재 기존 동상방지층 설계법에 따르면, 동상방지층은 포장체의 구조적 적정성과는 무관하게 온도조건에 따른 동결깊이에 따라 일률적으로 결정되고 있다. 이러한 동결깊이를 포장구조설계에 적용함으로써 포장의 과다설계 우려가 있다. 따라서 본 논문에서는 노상층, 동상방지층, 보조기층의 역학적 실험을 실시하여 동상민감성을 판단하고 실규모 현장도로 모형축소 실험을 실시하였다. 동상민감성을 판단하기 위하여 토층별 온도, 동결팽창량, 부동수분 및 동결깊이를 측정하였다.

• 한국수정란이식학회지
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• 제12권3호
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• pp.315-324
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• 1997

This study was undertaken in an effort to develop a cryopreservation system of immature and mature porcine oocytes. For this aim, the experiments were designed to examine the effect of cryoprotectants and equdibration time on the viability of frozen-thawed oocytes by using trypan blue(TB) and fluorescene diacetate(FDA) test. The viability of frozen immature oocytes evaluated by TB test was slightly higher than that of frozen mature oocytes. The viability(25.O%) after IVM of frozen-thawed immature oocytes greatly decreased that(42.9%) of oocytes just after thawing, but it was higher than frozen-thawed mature oocytes(15.8%). When immature oocytes were equilibrated for 10, 20 and 30 minutes before freezing the oocyte viability was 20.0, 31.3 and 42.9%, respectively. There was a tendency for long equilibration before oocyte freezing to be more effective for the immature oocytes and a short equilibration time for mature oocytes. Although there was no difference in viability index of frozen oocytes hetween the viability test methods, the index of TB test was slightly higher than that of FDA test. The viability(FDA test) of frozen-immature oocytes with 3 different crtoprotectants was 22.2% for propylene glycol(PG), 9.3% for polyehtylene glycol(PEG) and 65.6% for PG+PEG, in which PG+PEG was more protective against freezing effect.

• 한국가축번식학회지
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• 제12권2호
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• pp.84-90
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• 1988

This study was done with mouse embryos to determine effects of the freezing media with or without 10% sucrose, and seeding methods (pincette, no seeding, liquid nitrogen gas phase and copper wire coiled straw) on embryo survival were determined using the FDA test. The summarized results are the following. 1. The FDA score found with copper wire coiled straw, no seeding, pincette and liquid nitrogen gas phase was 3.6, 3.6, 3.3 and 3.0, respectively. There were no significant differences. 2. The embryo score shows higher (P<0.05) survival rate using a freezing medium with sucrose than the one without it. Among the seeding procedure, better resutls are copper wire coiled straw and no seeded. 3. The results suggest that copper wire coiled seeding no seeding be as good as seeding when the mouse embryos were frozen in a liquid nitrogen container using both the freezing and dilution media containing 10% sucrose.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2011년도 추계 학술논문 발표대회
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• pp.105-106
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• 2011

The present tests examined the resistance to freezing and thawing of alkail-activated (AA) slag concrete having compressive strength between 30~56 MPa. To enhance the compressive strength and resistance to freezing and thawing of AA slag concrete, Na ions were used for an activator. Test results revealed that the resistance to freezing and thawing of AA slag concrete is comparable to that of cement concrete when compressive strength is more than 50 MPa.