• Journal of Embryo Transfer
• /
• v.14 no.2
• /
• pp.99-106
• /
• 1999

핵 이식에 공여되는 수핵난자의 효과적인 동결보존을 위하여 한우 성숙난자를 1.0 M dimethylsulfoxide(DMSO) 또는 1.0 M glycerol이 함유된 동결보호제를 이용하여 처리하거나, 동결보호제 처리 후 완만동결법을 이용한 동결융핼르 시행하여 상기 실험처리로 야기되는 투명대 경화현상을 관찰하였다. 도축장 유래의 난소에서 미성숙난자를 채취한 후 10% 소 태아혈청을 함유한 TCM-199을 이용하여 22∼24 시간 동안 체외성숙배양을 이해하였다. 배양후 작출된 성숙난자를 각각의 동결보호제로 처리, 혹은 처리 후 동격융해한 후 protease를 이용하여 투명 대의 경화현상 발생의 빈도를 조사하였다. 또한 동격란을 동결정액을 이용한 체외수정에 공여한 후 정자 침입농도능을 조사하였다. 동결보호제로 처리한 난자에 있어서 보호제의 종류와 관계없이 투명대 경화현상이 유의적 (P<0.05) 으로 증가하였으나 이후의 동결융해 처리에 의한 추가적인 경화현상의 발생은 증가하지는 않았다. 또한 투명대 경화현상의 발생양상을 동결보호제 처리 후 10분 간격으로 측정한 결과 DMSO의 경우 처리후 10분, glycerol의 경우 처리 후 20분 후부터 유의적으로 차를 발견할 수 없었으며, 수정율 및 난자 1개당 침입한 정자의 수는 동결란에서 유의적으로 증가하지 않았다. 본 연구의 결과 동결난자의 투명대 경화현상은 동결보호제 처리과정에서 이미 일어나지만, 이러한 투명대 경화현상이 난자의 동결보존 후 수정능에는 현자한 영향을 미치지 않는다는 사실이 규명되었다.

• Journal of the Korean association of regional geographers
• /
• v.7 no.1
• /
• pp.97-106
• /
• 2001

There are a few interesting areas which show freezing during summer season in Korea, three of them are especially important. They are located at Milyang(Gyungnam province), Uisung and Chungsong(Gyungbook province). They are named Eoleumgol(ice-valley) or Binghyul(ice-cave). The purpose of this study is to clarify geomorphological and geological characteristics about the distribution areas of freezing during summer season in Korea in relation to previous works, which have been studied in hydrological or micro-climatological viewpoints. The main results are summarized as follows. 1) The main geomorphological and geological characteristics in the distribution areas of freezing during summer season (1) Thick debris accumulated slope within deep valley (2) North facing slope (3) The component debris of volcanic rock such as andesite or rhyolite 2) The ice-cave as a system that give rise to freezing phenomenon in summer season is closely related to talus slope. The ice-cave has thick accumulated debris and lots of vacant spaces within the rock deposits, some of vacant spaces are very big and connected with underground water system. 3) A partly freezing within underground water system is required freezing phenomenon in summer season. Judging from this point of view, two ideas are suggested; one is the evaporation theory, another is that the frozen condition in winter remains untill late summer.

• Journal of the Korean Geosynthetics Society
• /
• v.10 no.4
• /
• pp.93-103
• /
• 2011

In order to design suitable geo-structures in cold region, it is generally required to consider the mechanical properties of permafrost soils. 'Frost heave' as one of the primary phenomenon is considered to be an important factor together with 'adfreeze bond-strength' and 'creep deformation' for structural design process in permafrost area. Therefore, the fundamental study for frost heave has to be preceded for design of geo-structures in cold region. While various experimental apparatuses have been developed, there still exist a certain level of limitation to evaluate the frost-heave characteristics as design parameters. In this paper, a new type of experimental apparatus is proposed to evaluate the engineering characteristics of frost heave in permafrost soils and a set of verification test results is presented. Based on the verification tests, the proposed apparatus is a suitable to obtain frost characteristics of soils.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.21 no.2
• /
• pp.207-212
• /
• 1992

To analyze the freezing phenomena of foodstuffs, the numerical freezing model with 3 steps was established. When water and 2% agar gel were used as samples, Neumann's solution was well matched with experimental results by the numerical model. However, in the case of 20% gelatin gel and pork meat, Weiner's solution was better than Neumann's solution. This numerical freezing model was proved to be good model to describe the freezing phenomena with phase change in the point of versatility and precision.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.12 no.5
• /
• pp.399-405
• /
• 2010

The accumulated displacements and fatigues of rock are increased by the stress-hysteresis, induced from repeated frost-thawing. Also the shear strength is decreased by them continuously. The stress-hysteresis is affected by the atmospheric temperature changes, whose behavior is visco-elasticity, usually. Therefore, to do ideal body analysis, Kelvin model could be used to analyze the frost-thawing behavior in winter. In general, rock slope failure occurs by the deterioration of rocks, which is caused by the repetition of freezing-thawing process. In order to keep the safety of such rock mass structures the deterioration process of rock needs to be described quantitatively using some meaningful parameters. In this work, the deterioration process in freezing-thawing cycle of tuff, which is a famous soft porous rock, is investigated through laboratory tests and successfully described as a differential equation for the change of porosity. And then, the deterioration of the mechanical properties of rock, such as Young's modulus and uniaxial compressive strength, are quantitatively described as a function of the porosity.

• Journal of Energy Engineering
• /
• v.4 no.3
• /
• pp.420-428
• /
• 1995

현재 사용하고 있는 액화천연가스 기화기는 관내부로 -162$^{\circ}C$의 액화가스가 흐르고, 관외부로 발전소 증기응축기 출구에서 배출된 20~3$0^{\circ}C$의 해수를 흐르도록 하여, 두 유체사이의 온도차로 기화시키는 간접접촉방식 열교환기가 사용되고 있다. 그러나 간접접촉방식 열교환기는 두 유체사이의 큰 온도차로 인한 금속재료의 피로현상과 해수의 염분에 의한 재질의 부식 및 미생물 부착 등의 원인으로 열전달효율이 저하되고 있다. 따라서 본 연구는 관을 중간매체로 하는 간접접촉식 열교환기대신 액화천연가스와 기화용수인 물을 직접접촉시키는 방법으로 이용하여, 위와 같은 문제점들을 근본적으로 해결하려 한다. 본 실험에서는 기화기내의 수위 500 mm와 물의 유량 10 l/min을 일정하게 고정시키고, 액화천연가스의 유량 0.12 ㅣ/min, 0.36 l/min, 0.6 l/min, 기화기내의 압력을 100 kPa, 300 kPa, 500kPa로 변화시키면서 기화기내의 기포, 온도분포, 급팽창현상, 동결현상 및 기화후 수분함유량등의 비등특성을 규명하였다. 실험결과 기화기내의 압력이 증가할수록 기포는 작고 균일한 분포를 이루고, 폭발적인 급팽창현상은 일어나지 않았다. 또한 동결현상은 액화천연가스의 기화를 방지하지 못하였으며, 기화된 천연가스내의 수분함유량 몰%는 압력과 유량이 증가함에 따라 감소하는 경향을 보이고 있다.

• 한국방재학회:학술대회논문집
• /
• 2011.02a
• /
• pp.82-82
• /
• 2011

현재 도로 포장 설계시 동결심도의 결정은 30년간 관측한 기상자료 분석을 통해서 얻은 동결지수를 근거로 하여 동결심도를 산정한다. 그러나 기후 온난화 현상 등 변화된 기상조건과 대기온도를 근거로 작성된 동결지수와 대기온도에 따른 실제 포장 내부의 온도 변화를 반영하지 못하고 있다. 따라서, 본 연구에서는 설계시 산정된 동결심도와 실제 현장의 동결심도의 차이를 확인하기 위하여 한반도 북부지역을 동결지수에 따라 동결지수 $550{\sim}650^{\circ}C{\cdot}$일, $450{\sim}550^{\circ}C{\cdot}$일, $350{\sim}450^{\circ}C{\cdot}$일, $350^{\circ}C{\cdot}$일 이하로 구분하여 15개 지역을 선정하였고, 각 지역별로 절토부, 절성경계부, 저성토부(2m 이하 성토부) 구간으로 45단면을 구분하여 현장계측시스템을 구축하였다. 그리고 현장계측시스템으로부터 얻어진 대기온도와 포장층별 온도를 이용하여 현장 동결심도를 산정하고 동결심도 산정식의 동결심도와 비교하였다. 또한, 현장 동결심도를 이용하여 동결심도선도를 작성하였다.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.11a
• /
• pp.277-280
• /
• 2008

Reinforced concrete structures have an excellent durability under a good construction and continuous maintenance. But reinforced concrete construction is influenced by atmospheric phenomena and it is creating a deterioration. One of the deterioration cause on concrete is a freezing and thawing action. Freezing and thawing leads to the reduction in concrete durability by the cracking or surface spalling. If we are carried out freezing and thawing, deterioration of reinforced concrete construction will be reduction. Therefore, this study was performed to investigate the flexural behavior of reinforced concrete beams exposed to freezing and thawing cycles. Thee presence of damage and cycles were considered as variablees in this study.

• Journal of the Korean Geotechnical Society
• /
• v.29 no.1
• /
• pp.81-92
• /
• 2013

This paper presents the results of a numerical investigation into the behavior of retaining wall subject to cycles of freezing and thawing due to seasonal temperature change. The thermo-hydro-mechanical coupled finite element modeling strategy was first established to simulate the wall behavior. A series of finite element analyses were then performed on a range of conditions representing seasonal temperature change characteristics. The results indicated that the average freezing temperature and the number of cycles of freezing and thawing were the primary influencing factors for the wall behavior. Also revealed was that the duration of freezing period does not significantly affect the wall displacement and the lateral earth pressure, and that the earth pressure on the wall does not significantly change due to the freezing and thawing action suggesting that the increase in the wall displacement during the freezing and thawing action may be attributed to degradation of backfill due to the freezing and thawing action.

• Journal of Advanced Marine Engineering and Technology
• /
• v.23 no.3
• /
• pp.275-283
• /
• 1999