• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1546-1551
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• 2004

This paper presents a mathematical model to predict the frost properties and heal and mass transfer within the frost layer formed on a cold plate. The laminar flow equations for the air-side are analyzed. and the empirical correlations of local frost properties are employed in order to predict the frost layer growth. The correlations of local frost density and effective thermal conductivity of frost layer, obtained from various experimental conditions, are derived as functions of various frosting parameters (Reynolds number, frost surface temperature, absolute humidity and temperature of moist air, cooling plate temperature, and frost density). The numerical results are compared with experimental data and the results of various models to validate the present model, and agree well with experimental data within a maximum error of 10%. The heat and mass transfer coefficients obtained from the numerical analyses are presented, as the results, it is found that the model for frost growth using the correlation of heat transfer coefficient without solving air flow have a limitation in its application.

• 한국건축시공학회지
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• 제19권1호
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• pp.59-66
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• 2019

고로시멘트와 내한촉진제를 병용한 모르타르의 수축특성 및 수축성상에 미치는 영향에 대해 검토했다. 그 결과, OPC, BB 모두 내한촉진제를 첨가함에 따라 굳지 않은 성상에 미치는 영향은 작고, 초기재령부터 압축강도는 커진다. 또한, 내한 촉진제를 표준 사용량 이상으로 다량 사용할 경우에는 초기재령에 있어서의 팽창거동, 특히 강도발현과 팽창성의 관계에 대해 검토할 필요가 있다. 한편, 내한촉진제를 첨가함으로써 OPC, BB 모두 길이변화는 증가하는 경향을 확인할 수 있었다. 내한촉진제를 첨가함에 따라 직경 30nm 이하의 세공량, 특히 직경 20~30nm의 세공량 및 ink-bottle 세공량이 감소하여 수축량은 커지게 되며, 이 범위의 세공량의 변화가 수축성상에 미치는 영향이 크다고 판단된다.

• Corrosion Science and Technology
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• 제3권3호
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• pp.87-97
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• 2004

This paper presents a new approach with meso scale structure models to express mechanical property, such as stress - strain relationships, of concrete. This approach is successful to represent both uniaxial tension and uniaxial compression stress - strain relationship, which is in macro scale. The meso scale approach is also applied to predict degraded mechanical properties of frost-damaged concrete. The degradation of mechanical properties with frost-damaged concrete was carefully observed. Strength and stiffness in both tension and compression decrease with freezing and thawing cycles (FTC), while stress-free crack opening in tension softening increases. First attempt shows that the numerical simulation can express the experimentally observed degradation by introducing changes in the meso scale structure in concrete, which are assumed based on observed damages in the concrete subjected to FTC. At the end applicability of the meso scale approach to prediction of the degradation by combined effects of salt attack and FTC is discussed. It is shown that clarification of effects of frost damage in concrete on corrosion progress and on crack development in the damaged cover concrete due to corrosion is one of the issues for which the meso scale approach is useful.

• 대한기계학회논문집B
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• 제28권6호
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• pp.665-671
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• 2004

A mathematical model is presented to predict the frost properties and heat and mass transfer within the frost layer formed on a cold plate. The model consists of the laminar flow equations for air-side and the empirical correlation of local frost density. The correlation of local frost density used in this study is obtained from various experimental conditions by considering frosting parameters. The numerical results are compared with experimental data to validate the model, and agree well with experimental data within a maximum error of 9%.

• 설비공학논문집
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• 제18권2호
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• pp.122-128
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• 2006

In this paper, frosting experiments were conducted with variations of frosting parameters in order to obtain the correlations of frost properties. As a result, the local thickness, density, and surface temperature of the frost layer were presented. The dimensionless correlations for the frost thickness, frost density, frost surface temperature and heat transfer coefficient were derived as functions of dimensionless frosting parameters by using a dimensional analysis.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.1487-1493
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• 2008

The frost heaving is related with thermal conduction rate and permeability. If the thermal conduction rate can be controlled, it is effective to prevent from frost heaving. If soil mixed with shredded tire which has relatively lower thermal conduction rate than soil, it helps preventing from frost heaving. However, in this case, the shear strength can get weak. In this study, we compared thermal conduction rate of soil and shredded tire, and test uniaxial compression strength of soil which is mixed with shredded tire and cement in different ratio.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 춘계 학술발표회
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• pp.1164-1171
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• 2010

Korea is considered to be a seasonal frozen soil area that is thawed in the spring, and most of the area is frozen in winter as to the characteristic of geography. In the current design codes for anti-freezing layer, the thickness of anti freezing layer is calculated by freezing depth against the temperature condition. Therefore, they have a tendency of over-design and uniform thickness without the considerations of thermal stability, bearing capacity and frost susceptibility of materials. So, it is essential for studying the appropriateness and bearing capacity besides the seasonal and mechanical properties of pavement materials to take a appropriate and reasonable design of the road structure. In this research, the evaluation of frost susceptibility on subgrade, ant-freezing layer, sub base was conducted by means of the mechanical property test and laboratory field road model downed scale experiment. The temperature, heaving amount, heaving pressure and unfrozen water contents of soil samples, the subgrade, anti-freezing layer, sub base soils of highway construction site, were measured to determine the frost susceptibility.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2016년도 춘계 학술논문 발표대회
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• pp.203-204
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• 2016

In this research, it used cement power and reduction slag, which generates high hydration heat in hydration reation without heat cure below -5℃ degree. Purpose of final research is preventing freezing and thawing by making the compressive strength 5MPa in 3days below zero temperature due to own heat of concrete. and it is the result of physical characteristic and thermal property evaluation of reduction slag. Because reduction sag generates high hydration heat, compressive strength development is excellent. By generating highly Hydration heat by C₁₂A₇ and C₃A in reduction slag, compressive strength is developed in low temperature. In case of displacing only reduction slag without SO₃, it is indicated that quick-setting occurs by shortage of SO₃. For preventing quick-setting, gypsum is used essentially. According to this research result, in case of using reduction slag and gypsum as a ternary system, Compressive strength developed 5MPa in 3days below zero temperature. It is identified to prevent early frost damage of concrete below zero temperature.

• 한국도로학회논문집
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• 제12권2호
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• pp.71-79
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• 2010

겨울에는 시베리아기단의 영향으로 한랭 건조한 대륙성 고기압의 영향을 받아 춥고 건조하여 1월 평균기온이 $-6{\sim}-7^{\circ}C$의 영하의 온도로 낮아져 지반동결시 수분이동으로 동상현상이 발생하여 도로의 불균형 동결팽창을 초래하며, 결국 포장체를 파손시킨다. 동상발생시 토립자는 모관력에 의해 지하수를 흡수하여 아이스렌즈를 형성하며, 이 모관 흡수력은 토립자의 크기에 영향을 받는다. 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 온도 조건에 따른 동결깊이에 따라 일률적으로 결정되고 있다. 이러한 동결깊이를 포장구조설계에 적용함으로써 포장의 과다설계 우려가 있다. 따라서 본 논문에서는 도로 동상방지층의 효용성 검증 및 설치기준 확립을 위해 실내동결시스템을 활용하여 도로 노상토의 동상 특성에 대한 민감성을 판별, 도로건설 현장 노상토에 대한 역학적 특성과 실내 동결 시험을 수행하였으며, 외부 동결온도의 지속 조건에 대한 시료의 온도변화, 동상팽창압, 동상팽창량, 부동수분 등의 결과값을 통하여 동결 과정에 따른 지반공학적 특성을 평가하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.687-690
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• 2005

Recently, to consider financial and constructive aspect, usage of Admixture, like Blast- Furnace Slag and Fly-Ash, are increased. These mineral admixtures, a by-product of steel industry, have many advantage, to reduce the heat of hydration, increase in ultimate strength, improve workability and etc. But it also reduces early-age strength, so it is prevented from using of Blast-Furnace Slag at cold-weather-concrete. In this study, for the purpose of increasing usage of mineral admixtures, like Blast-Furnace Slag and Fly ash, it is investigated the strength properties of concrete subjected to under low temperature According to this study, if early curing is carried out before having frost damage, the strength of concrete, subjected to frost damage, is recovered. And to consider increasing effect of strength, it is more effective to use of mineral admixtures, especially to use blast furance slag.