• 콘크리트학회논문집
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• 제11권4호
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• pp.117-127
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• 1999

In concrete incorporating high volume ground granulated blast-furnace slag that has frozen at early age, to evaluated the results of resistance to freezing and thawing is very difficult because the hydration of the concrete increases over the duration of rapid freezing and thawing test. Hence, the dynamic modulus of elasticity of specimens after freezing and thawing will be favorable results unless the hydration effect is taken into consideration. In this study, a method of evaluating to the resistance to freezing and thawing of concrete subjected freezing at early age, in which the effect of hydration is modified for its increase during rapid freezing and thawing test, is investigated.

• 한국지반신소재학회논문집
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• 제8권3호
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• pp.35-44
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• 2009

본 연구는 유류나 각종 비수용성오염물질로 오염된 지반에 인공동결공법을 이용한 차수벽을 형성하여 지하수의 이동으로 인한 오염물질의 확산을 방지하기 위한 기초적 실험결과이다. 즉, 인공동결공법을 사용하여 동결차수벽을 형성하는데 있어 각각 포화도가 80%, 90%인 시료를 조성하여 동결모형실험을 수행하였다. 인공동결공법을 이용하여 형성시킨 동결차수벽이 동결시간이 길어짐에 따라 포화도 90%인 시료가 포화도 80%인 시료보다 1시간정도 차수벽이 빨리 형성되었다. 또한, 동결진행시간 12시간 이후의 동결차수벽은 두 시료 모두 가장 얇게 형성된 곳이 50mm의 두께로 형성되어 시간에 따른 동결영역확대로 폐기물 매립지 및 오염지역의 차폐를 위한 차수벽, 오염물질 흐름제어 등에 적용할 수 있을 것으로 판단된다.

• Asian-Australasian Journal of Animal Sciences
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• 제30권7호
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• pp.1021-1028
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• 2017

Objective: The objective of this study was to evaluate the effects of ageing time of lamb loins prior to freezing on technological characteristics and oxidation stability of coarse ground lamb loin sausage using in a model system. Methods: Lamb loins (M. longissimus lumborum, n = 25) were aged at $-1.5^{\circ}C$ for 0, 1, 2, 3, and 8 wk and then frozen for the remaining days (a total of 30 wk). The aged/frozen/thawed lamb loins were ground, and model sausages were formulated with 75% aged/frozen/thawed lamb loin, 25% water, 1.5% sodium chloride (NaCl) and 0.3% sodium tripolyphosphate. The pH and thaw/purge loss of aged/frozen/thawed lamb loins were evaluated, and protein functionality (protein solubility and emulsifying capacity), water-holding capacity and textural properties of model sausages were determined. Cooked model sausages were vacuum-packaged in a plastic bag and displayed under continuous fluorescent natural white light ($3^{\circ}C{\pm}1^{\circ}C$). Colour and lipid oxidation of the cooked model sausages were evaluated on 0 and 21 d of display storage. Results: Ageing prior to freezing had no impact on pH and purge/thaw loss of lamb loins and the colour of cooked sausages (p>0.05) made from the loins. Lamb loins aged for at least 3 wk prior to freezing numerically improved total and myofibrillar protein solubilities (p>0.05) and emulsion activity index (p = 0.009) of meat batter, but decreased cooking loss (p = 0.003) and lipid oxidation (p<0.05) of model sausages. Conclusion: This study suggests that post-mortem ageing of raw meat prior to freezing could improve water-holding capacity and lipid oxidative stability of sausage made from the meat.

• Geomechanics and Engineering
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• 제27권5호
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• pp.433-445
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• 2021

Artificial ground freezing (AGF) is a commonly used geotechnical support technique that can be applied in any soil type and has low environmental impact. Experimental and numerical investigations have been conducted to optimize AGF for application in diverse scenarios. Precise simulation of groundwater flow is crucial to improving the reliability these investigations' results. Previous experimental research has mostly considered horizontal seepage flow, which does not allow accurate calculation of the groundwater flow velocity due to spatial variation of the piezometric head. This study adopted vertical seepage flow-which can maintain a constant cross-sectional area-to eliminate the limitations of using horizontal seepage flow. The closure time is a measure of the time taken for an impermeable layer to begin to form, this being the time for a frozen soil-ice wall to start forming adjacent to the freeze pipes; this is of great importance to applied AGF. This study reports verification of the reliability of our experimental apparatus and measurement system using only water, because temperature data could be measured while freezing was observed visually. Subsequent experimental AFG tests with saturated sandy soil were also performed. From the experimental results, a method of estimating closure time is proposed using the inflection point in the thermal conductivity difference between pore water and pore ice. It is expected that this estimation method will be highly applicable in the field. A further parametric study assessed factors influencing the closure time using a two-dimensional coupled thermo-hydraulic numerical analysis model that can simulate the AGF of saturated sandy soil considering groundwater flow. It shows that the closure time is affected by factors such as hydraulic gradient, unfrozen permeability, particle thermal conductivity, and freezing temperature. Among these factors, changes in the unfrozen permeability and particle thermal conductivity have less effect on the formation of frozen soil-ice walls when the freezing temperature is sufficiently low.

• 한국터널지하공간학회 논문집
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• 제18권2호
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• pp.175-181
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• 2016

본 연구는 액체질소와 같이 급속 동결이 가능하면서 질식의 위험을 배제할 수 있는 냉매로서 액화공기를 선정하였고 이의 적용성을 평가하였다. 액화공기의 안정성을 평가하기 위해 액체질소와 액체산소가 혼합된 액화공기의 산소 농도가 산업안전보건법에 제시된 산소 농도 기준에 부합되는지를 실험적으로 검증하였으며, 액체질소 및 액체산소의 혼합 비율, 액화공기 저장용기의 압력변화 및 유량변화에 따른 액화공기 산소 농도변화를 살펴보았다. 그 결과, 액체질소 및 액체산소를 8:2로 혼합하였을 경우 산업안전보건법에 제시된 산소 농도 기준에 부합되는 것을 확인하였다. 액화공기 저장용기의 압력변화 및 유량변화는 액화공기의 산소 농도에 큰 영향을 미치지 않는 것으로 나타났다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 학회창립 10주년 기념 1999년도 가을 학술발표회 논문집
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• pp.763-766
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• 1999

The objective of this study was to investigate the influence of low temperature curing on resistance of freezing and thawing of self-compacting concrete placed in cold weather regions. The experimental study results indicated that the self-compacting concrete incorporating ground granulated blast-furnace slag showed good resistance to freezing and thawing, and the self-compacting concrete cellulose viscous agent had relatively poor resistance to freezing and thawing.

• 한국지반공학회논문집
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• 제34권11호
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• pp.43-55
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• 2018

인공동결공법은 일시적으로 지반의 강성을 높이고 투수계수를 낮추는 지반개량공법으로 지반에 적용가능하다. 하지만, 지하수 흐름과 지반의 불균질성은 동결구근 형성을 불확실하게 하여 공법에 대한 신뢰성을 저해한다. 동결지반 대한 열-수리 유한요소 해석 프로그램을 이용하여, 인공동결공법에서 지하수 흐름속도와 지반의 층상 비균질이 얼음벽 형성을 미치는 영향을 분석하였다. 지하수의 흐름은 원형의 동결구근을 원형에서 타원형을 변형시키며 얼음벽의 완성 소요시간을 증가시킨다. 기존의 이론식은 인접 동결구근의 열적 상호작용을 무시하여, 얼음벽의 완결시간과 한계유속을 과대 평가하였다. 수치해석 결과를 바탕으로 수정식을 제시하였으며 무차원 얼음벽 완결시간에 대한 제안식을 검증하였다. 층상의 비균질 지반에서 투수계수가 큰 지층의 두께와 상대적인 투수계수비는 얼음벽 완결시간과 한계 유속에 중요한 인자인 것으로 나타났다.

• 항공우주시스템공학회지
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• 제2권3호
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• pp.40-44
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• 2008

T-50 ECS(environment control system) was designed to have freezing protection for the condenser. However during the ground and flight test, the freezing problem was occurred. This paper deals with the analysis of the freezing problem and introduces anti-freezing design using ADI(Active De-Icing) logic to solve the condenser freezing problem of T-50 ECS

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2014년도 추계 학술논문 발표대회
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• pp.129-130
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• 2014

In the case of concrete structures which have been recently exposed to the marine environment, durability is greatly reduced by the freezing-thawing action. When it is used by appropriately replacing the ground granulated blast-furnace slag(GGBS) that is a industrial by-product, the concrete structure of marine environment is known to have a durability to freezing-thawing resistance. In this experiment, micropore in accordance with a replacement ratio of GGBS was confirmed to show different results respectively. The freeze-thaw resistance was showed different aspects respectively because it is different the amount of water in the pore due to the difference of micropore. Therefore, in this study, the freezing-thawing resistance of sea water by variation of micropores of slag concrete had been evaluated.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 봄 학술발표회 논문집
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• pp.329-336
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• 2002

The earth structures and in-ground LNG tank, and buildings can be constructed with using artificial freezing method on the reclaimed land. In this study, upon freezing a saturated soil in a closed-system from the top, a considerable pressure was developed. The pressure is the result of the surface energy of a curved ice-water interface. The most significant of these parameters will have the greatest effect on the classification. In order to establish frost-susceptibility criteria based on frost heaving expansion pressure, more soils have to be tested. This study was initiated to investigate the soils frost heaving expansion pressure and moisture characteristics resulting from freezing and freezing-thawing cycle process. Weathered granite soils, sandy soil, sandy soil were used in the laboratory freezing test subjected to thermal gradients under closed- systems.