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동결토(凍結土)의 압축강도(壓縮强度)에 관한 실험적(實驗的) 연구(硏究)
유능환 ( Ryu Neung Hwang ),최중돈 ( Choi Joong Dae ),유영선 ( Ryu Young Sun ),조영택 ( Jo Young Tack ) 한국농공학회 1993 韓國農工學會誌 : 전원과 자원 Vol.35 No.4
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 of freezing temperature and repeated freezing-thawing cycle as well as the density of the soil and applied lading condition. This study was initiated to describe the effect of the freezing temperature and repeated freezing-thawaing 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 tempera-ture 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. Scant modulus was responded sensitively to material of the loading plates, increased with decrease of temperature down to -10℃, 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 5℃, but the strength below -5℃ were different from the equation and showed a strong dependency on temperature and deformation speed. When the skew was less then 20 degress, 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. Expecially, 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 technique for the strength reduction be developed.
동결(凍結)-융해작용(融解作用)이 흙의 강도특성(强度特性)에 미치는 영향(影響) (IV) - 단열재(斷熱材)를 삽입(揷入)한 동결성토(凍結盛土)의 단열거동(斷熱擧動) -
유능환 ( Ryu Neung Hwan ),박승범 ( Park Seung Bum ),유영선 ( Ryu Young Sun ) 한국농공학회 1990 韓國農工學會誌 : 전원과 자원 Vol.32 No.3
This paper was analized the thermal conductivity of polystylene (TENSAR- GEOGRID) embeding into the subbase through frost penetration depth, frost heave, change of bearing capacity, and soil moisture movement due to freezing, thawing and icing actions, and their results were as follows : 1. The change of temperature into the sub-base was much increased by the Tensar-Geogrid insertion, and the frost penetration and frost heave were decreased as the thinner of the insulation thickness but the thawing velocity of melting period was appeared to be faster in case of non-insulated. 2. The frost heave had a close relationship with the thickness of insulations which was reasonably included anti-frost effects. 3. The moisture content during the freezing period of upper layer of the insulation insertion was increased by 15 per cent but it was returned to initial state of the thawing period, and at the down layer temporarily increased by 10 per cent and returned to the original state at once. 4. The insulation was acted as a function of distribution of surcharge, and the settlement of the sub-base was about 1.5 mm under 15 tonnage of load and which was included within the allowable limits. 5. The sliding resistance due to the icing which was induced by the insulation insertion into the sub-base was appeared as more 40 per cent than noninsulation area, so that the insulations should be restricted on the place such as mountains, curved and cross area which were required the braking power under the traffics.
유능환 ( Ryu Neung Hwan ),( Alan Mcgown ),유영선 ( Ryu Young Sun ) 한국농공학회 1990 韓國農工學會誌 : 전원과 자원 Vol.32 No.2
This study was carried out to find the effects of freeze thaw behaviour on the thermal characteristics of soil layer, for the measurement of thermal conductivity, the styrofoam base and the base replased with gravely sand were constructed and their results were as follows ; 1. The frost heave was appeared to be top around the end of January, and the value in the case of base insulated with styrofoam was shown to be eight times larger than that of the base replased with gravely sand. 2. The frost penetration depth was peaked between the 20th and 30th of January, the depth in case of styrofoam base was about 80 cm and the gravely sand base, 140 cm, and the former was seemed to be more effective on the thermal conductivity than the latter. 3. The relationship between frost heave and frost penetration depth was expressed as y=e 0.571x-4.087, and that we can easily estimate the frost penetration depth on the ground of the equation through the simple measurement of the frost heave. 4. It was appeared that construction cost was decreased by 40% in the case of base insulated with styrofoam compared to the base replased with gravely sand on the same frost resistance capacity. The economic construction range was seemed to be more than 100 meters.
이상락,김준식,류혜정,권태찬,김천수,이광숙,전효진,유영선,김명성,박근수 啓明大學校 醫科大學 1998 계명의대학술지 Vol.17 No.1
저자들은 Turner 증후군으로 확진된 환아에서 대동맥 축착이 동반된 1례를 경험하였기에 문헌 고찰과 함께 보고하는 바이다. We reviewed a 24 month old girl with clinical features of webbed neck, low posterior hairline, juxtaductal coarctation of the aorta and was confirmed by karyotyping 45XO. Surgical repair of coarctation of the aorta was performed using the techniques of resection and end-to-end anastomosis. The postoperative course was excellent.