• 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.

• 생물환경조절학회지
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• 제10권4호
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• pp.244-250
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• 2001

저온은 배추 묘에서 1주일동안 RNA함량과 단백질 함량을 증가시켰고, 당 함량에 있어서도 많은 변화를 유발했을 뿐만 아니라 저온순화시 치사온도에서 생존율 또한 증가하였다. 이런 결과에서 보듯이 이러한 변화는 내동성의 발달과 관련되어 있는 것으로 생각할 수 있다. 5$^{\circ}C$에서 처음 24시간처리 했을 때 12시간 이후부터 내동성이 증가했으며 5일째 가장 크게 증가하였다. 치사온도에서의 생존율도 저온처리한지 12시간 후부터 증가해서 5일 후 가장 높은 생존율을 보였다. 수용성당 함량은 저온순화 한지 1일 후부터 크게 증가했다. 몇몇 주요한 당 함량에서 볼 수 있듯이 포도당(Glucose)은 저온처리된 배추묘에서 함량이 가장 많은 당 성분으로 저온처리된 배추묘와 처리되지 않은 배추묘 사이에서 1일 후부터 계속 큰 차이를 나타냈으며 과당(Fructose)도 포도당과 비슷한 경향을 보였다. 저온처리를 시작할 때 자당(Sucrose)이 가장 많이 증가하는 경향을 보였고 처리 9시간 이후부터 큰 차이를 나타내기 시작했다. 당의 정량분석결과 배추묘에서 주요한 당 성분은 포도당이었으나, 저온처리시 크게 증가한 당 성분은 자당이었다. 최대내동성에 도달하기까지 5일이 걸렸으나 탈순화시 9시간후부터 생존율이 서서히 감소해 24시간만에 저온순화로 획득된 내동성이 모두 상실되었다. 전체 RNA와 수용성 단백질 함량 역시 24시간 경과 후 현저히 감소하였다.

• 한국농공학회지
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• 제35권4호
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• pp.55-66
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• 1993

Upon freezing a soil swells due to phase change and its compression stress increase a lot. As the soil undergo thawing, however, it becomes a soft soil layer because the 'soil changes from a solid state to a plastic state. These changes are largely dependent on freezing temperature and repeated freezing-thawing cycle as well as the density of the soil and applied loading condition. This study was initiated to describe the effect of the freezing temperature and repeated freezing-thawing cycle on the unconfined compressive strength. Soil samples were collected at about 20 sites where soil structures were installed in Kangwon provincial area and necessary laboratory tests were conducted. The results could be used to help manage effectively the field structures and can be used as a basic data for designing and constructing new projects in the future. The results were as follows ; 1. Unconfined compressive strength decreased as the number of freezing and thawing cycle went up. But the strength increased as compression speed, water content and temperature decreased. The largest effect on the strength was observed at the first freezing and thawing cycle. 2. Compression strain went up with the increase of deformation speed, and was largely influenced by the number of the freezing-thawing cycle. 3. Secant modulus was responded sensitivefy to the material of the loading plates, increased with decrease of temperature down to - -10$^{\circ}$C, but was nearly constant below the temperature. Thixotropic ratio characteristic became large as compression strain got smaller and was significantly larger in the controlled soil than in the soil treated with freezing and thawing processes 4. Vertical compression strength of ice crystal(development direction) was 3 to 4 times larger than that of perpendicular to the crystal. The vertical compression strength was agreed well with Clausius-Clapeyrons equation when temperature were between 0 to 5C$^{\circ}$, but the strength below - 5$^{\circ}$C were different from the equation and showed a strong dependency on temperature and deformation speed. When the skew was less then 20 degrees, the vertical compression strength was gradually decreased but when the skew was higher than that, the strength became nearly constant. Almost all samples showed ductile failure. As considered above, strength reduction of the soil due to cyclic freezing-thawing prosses must be considered when trenching and cutting the soil to construct soil structures if the soil is likely subject to the processes. Especially, if a soil no freezing-thawing history, cares for the strength reduction must be given before any design or construction works begin. It is suggested that special design and construction techniques for the strength reduction be developed.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2003년도 학술.기술논문 발표회
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• pp.63-67
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• 2003

There are many factors that generate the early deterioration of the concrete structure. As the one of the representative factors, we can think an invasion of the water, air and so on. The water and air invade in inside void along the capillarity and they become the cause that the durability like corrosion of layer department due to freezing and thawing, inside steel frame corrosion, and so on blacks. Therefore with covering permeability covering waterproofing material of fluid condition in outer wall, intercepting the deterioration factor due to the infiltration of water from outside and for salt damage of concrete layer department, freezing damage and neutralization, it needs, to improve durability of structure. This study separately examined physical and chemical specific of quality liguid siliceous of waterproofing material. Therefore as this applys the construction site, it improves the durability of concrete structure. Further this presents the application plan from the construction market against the new material.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2003년도 학술.기술논문발표회
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• pp.63-67
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• 2003

There are many factors that generate the early deterioration of the concrete structure. As the one of the representative factors, we can think an invasion of the water, air and so on. The water and air invade in inside void along the capillarity and they become the cause that the durability like corrosion of layer department due to freezing and thawing, inside steel frame corrosion, and so on blacks. Therefore with covering permeability covering waterproofing material of fluid condition in outer wall, intercepting the deterioration factor due to the infiltration of water from outside and for salt damage of concrete layer department, freezing damage and neutralization, it needs to improve durability of structure. This study separately examined physical and chemical specific of quality liquid siliceous of waterproofing material. Therefore as this applys the construction site, it improves the durability of concrete structure. Further this presents the application plan from the construction market against the new material.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 봄 학술발표회 논문집
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• pp.170-176
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• 1997

The published works on steam curing effect have been generally concentrated on the subject, "compressive strength". However a practical test for durable steam curing concrete products has not been performed in domestic. In this study, the maximum temperature of steam is considered as a major variable to investigate the freezing and thawing resistance of the steam curing concrete. All of the specimen were cured for 24 hours which included presteaming 4 hour. Finally we found that the most effective curing condition is the case of one-day and 14-day specimens after the 24 hours steam curing at $74^{\cire}C$ degree curing temperature. It is also found that the durability of one-day samples are much weaker than those of 14-day samples. Consequently, we can conclude that the samples that produced immediately after a steam curing are more possible to deteriorate from the freezing and thawing environment.vironment.

• 한국수산과학회지
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• 제15권2호
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• pp.111-116
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• 1982

말쥐치를 보다 효과적으로 이용하기 위한 하나의 방법으로서 말쥐치 동건품의 가공사건 및 저장중의품질변화를 실험하였다. 동결온도 $-10^{\circ}C$이고 송풍해동조건이 온도 $56\pm2^{\circ}C$, 풍속 1 m/sec 일 때 동결시간 10시간, 해동시간2시각, 동결 및 해동포수는 5소파 가장 적합하였다. 이 때 제품의 수분사양은 $23.6\%$, 수율은 $10.2\%$였다. 상온에서 함기포장하여 저장한 결과 90일까지는 품질에 큰 변화 없이 저장 가능했다. Omission test결과 제품의 맛에는 유리아미노산과 5'-mononucleotide가 주된 구실을 한다는 것을 알 수 있었다. 또한 말쥐치 동건품과 시판 동건명태는 관능 검사결과 맛, 냄새, 텍스튜어 등이 거의 비슷하였다.

• 한국가축번식학회지
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• 제10권2호
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• pp.175-181
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• 1986

These experiments were carried out to clarify the effects various kinds of cryoprotectants which were frequently used in freezing embryos of domestic animals on the survival of frozen-thawed mouse embryos. As cryoprotectant, glycerol, DMSO and methanol were used and the procedures of adding them in medium were practiced by one-step or six-step adding method. Morphologically normal mouse embryos developed to blastocyst by in vitro culture after freezing and thawing were transferred to pseudopregnant recipients by surgical procedures. The results obtained in these experiments were summarized as follows: 1. The survival rates of the frozen-thawed 8-cell embryos, morulas and blastocysts following one-step addition of glycerol were 83.6, 80.3 adn 70.3%, respectively, while following six-step addition of glycerol, 69.2, 56.3 and 66.7% respectively. 2. When glycerol, DMSO and methanol were used as cryoprotectant under the same condition of freezing and thawing, the survival rates of frozen-thawed embryos were 74.0, 76.1 and 37.6%, respectively. 3. The implantation rate of embryos transferred to pseudopregnant recipients after freezing and thawing was 49.2%.

• 한국작물학회지
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• 제50권2호
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• pp.67-72
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• 2005

Overwintering capacity, closely related to winter hardiness, of Chinese milk vetch planted with different sowing times and sowing practices was investigated to improve the incorporation into cropping system in Korea. The tolerance to low temperature was evaluated with $LT_50$ using leaf disc leaching method. Dry weight of CMV was reduced remarkably with delayed planting from Sep. 5 to Oct. 20. The differences in tolerance to freezing temperature were not conspicuous among CMV genotypes, however, the differences between genotype (collections at different regions) were due to the plant architecture, mainly to the leaf angle. The crouching genotype collected at central region of Korean peninsula, which showed excellent freezing tolerant, has planophile leaves. The feature of internal constituents of CMV genotypes did not show any noticeable differences with respect to the freezing tolerance which evaluated by leaf disc leaching experiment. To overcome the poor overwintering capacity, tolerant genotype should be developed by selection with considering the plant architecture. The reduction of CMV growth during overwintering period was ameliorated with furrow-sowing under late-sown condition, therefore, when the CMV is inevitably sown late after recommended time, the seeds should be sown on furrow to overcome the cold stress.

• 한국수정란이식학회지
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• 제11권2호
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• pp.125-135
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• 1996

The present study was carried out to investigate the effects of cryoprotectants, equilibration step, freezing rate, culture condition following in vitro fertilization, and age and development stage of embryo by freezing with conventional slow freezing and vitrification on survival of frozen-thawed Korean native cattle(KNC) blastocysts produced in vitro. The KNC blastocysts produced in vitro were equilibrated in 1.8M ethylene glycol or 1.4M glycerol and cooled from -6$^{\circ}C$ to -35$^{\circ}C$ at -0.3$^{\circ}C$ or -O.6$^{\circ}C$ /minute. When equilibrated in 1.8M ethylene glycol, survival rate of fiozen4hawed blastocysts was sarne in both -0. 3$^{\circ}C$ /min and -0.6$^{\circ}C$ /min cooling rate(71.4%). With the equilibration in 1.4M glycerol, survival rate was higher in -0.3$^{\circ}C$ /min(63.6%) than in -0.6$^{\circ}C$ /min cooling rate(53.8%). For vitrification of the KNC blastocysts produced in vitro, they were equilibrated in 2-step or 3-step exposure to vitrification solution(25% ethylene glycol + 25% glycerol). Survival rate was sirilar in both 2-step(45.0%) and 3-step exposure(47.4%). According to culture condition following in vitro fertilization, higher survival rate was obtained for blastocysts co-cultured with bovine oviductal epithelial cell(BOEC, 77.3%) than for those cultured with epidermal growth factor(EGF, 65.7%) or for those co-cultured with BOEG + EGF (54.8%). According to embryo age and development stage, higher survival rate was obtained for 7-day ernbryos(70.0%) than 8-day(56.8%) or 9-day(20.0%) for blastocyst stage and obtained for 8-day embryos(74.3%) than 7-day(62.5%) or 9-day(42.9%) for exponded blastocyst. In surnmary, higher survival rate of frozen4hawed KNC blastocysts produced in vitro were obtained by using ethylene glycol for cryoprotectant and -0.3$^{\circ}C$ /min for cooling rate. And higher survival rate were obtained with co-culture with BOEC for culture condition following in vitro fertilization and with 7-day blastocyst or 8-day expanded blasto cyst for embryo age and development stage.