• International Journal of Highway Engineering
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• v.3 no.1 s.7
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• pp.165-176
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• 2001

Joints in jointed concrete Pavement are designed to control against randomly occurred cracks within slabs, which may be caused by temperature or moisture variation. The advantage of these artificial cracks (joints) over naturally occurred cracks are easy access of protections, such as installation of joint seal and load transfer mechanism. The potential benefits of joint seals are to prevent infiltration of surface water through the joint into underlying soil and intrusion of incompressible materials (debris, fine size aggregate) in to the joint, which may prevent weakening of underlying soils and spallings due to excessive compressive stress, respectively. For the adequate design of joint seal, horizontal variation of joint widths (horizontal joint movements) are essential inputs. Based on long-term in-situ joint movement data of sixteen jointed concrete pavement sections in Long Term Performance Pavement Seasonal Monitoring Program (LTPP SMP), it was indicated that considerable Portion of joints showed no horizontal movements with change in temperature. This Phenomenon is called 'Joint Freezing'. Possible cause for joint freezing is that designed penetrated cracks do not occur at a joint. In this study, a model for the prediction of the ratio of freezing joints in a particular pavement sections is proposed. In addition, possible effects of joint freezing against pavement performance are addressed.

• Journal of the Korean Geosynthetics Society
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• v.13 no.3
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• pp.49-58
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• 2014

This paper presents the results of a reduced-scale physical model investigation into the behavior of retaining walls subject to cycles of freezing and thawing due to seasonal temperature change. Reduced-scale model walls equipped with a temperature control chamber that can simulate freezing and thawing conditions were first constructed and a series of tests were conducted with due consideration of different initial water contents of backfill soil and soil types. The results indicate that cycles of freezing and thawing process increase wall deformation as well as earth pressure acting on the wall. Also revealed was that the effect of the freezing and thawing cycles becomes more pronounced for cases with a larger initial water content and for soils with a larger fine content. Practical implications of the findings from this study are discussed in great detail.

• Food Science and Preservation
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• v.14 no.5
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• pp.469-473
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• 2007

The optimal formula for non-frozen pound cake was sought using a central composite design with a quadratic model, by response surface methodology (RSM). Behavior on supercooling, freezing time, theological properties, and sensory attributes of pound cake were studied by using various concentrations of sugar, sorbitol, and glycerol. The freezing temperature of standard pound cake was $-16.16^{\circ}C$. The hardness, freezing point temperature, and sensory properties were shown as a quadratic relationship whereas moisture content was analyzed by a linear model. Optimized formula for non-frozen cake were suggested to include (sugar:sorbitol:glycerol) 77.6:0.0:20.4, 60.0:32.8:16.4, and 70.8:11.2:19.6 (all % of total sugar) by RSM. The freezing tines of optimized non-frozen pound cake were reduced by $27{\sim}45%$. The freezing Points of optimized pound cake were depressed below $-20^{\circ}C$. Sorbitol and glycerol may be used as cryoprotectants and preserve the desired sensory attributes of pound cake at low temperatures.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.44 no.4
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• pp.362-369
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• 2008

The snow melting system by electric heating wires which is adopted in this research is a part of road facilities to keep surface temperature of the road higher than freezing point of water for melting the snow accumulated on it. The electric heating wires are buried under paved road at a certain depth and operated automatically and manually. Design theory, amount of heating, and installation standard vary according to economic situation, weather condition, installation place and each country applying the system. A main purpose of this study is figuring out the appropriate range of required heat capacity and installation depth and pitch for solving snowdrifts and freezing problems with minimum electric power consumption. This study was performed under the ambient air temperature($-2^{\circ}C$, $-5^{\circ}C$), the pitches of the electric heating wires(200 mm, 300 mm), heating value($250\;W/m^2$, $300\;W/m^2$, $350\;W/m^2$).

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.905-910
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• 2007

The cubicle of high speed train is the equipment where the important train- operating equipments are concentrated, so it requires the higher safety and reliability than any other equipment. Recently, the power car cubicle of KTX-II is, basically similar to that of KTX-I and HSR350x in its size, but consequently, as more sophisticated ATP/ATC and other parts are added, the order company points out the problem of rising temperature in summer. Especially, the interpretation about the possibility of guaranteeing the minimum freezing performance becomes necessary, when Fan Tray is out of order. This paper presents the method of improving the freezing performance while minimizing the effect of dust, and the method of guaranteeing the present freezing performance by the best arrangement of Fan Tray, when Fan Tray is out of order. And as a method of verifying this, we would like to predict the pressure, speed of a running fluid and temperature distribution of cubicle through the flow analysis.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.2
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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.

• Journal of Embryo Transfer
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• v.7 no.1
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• pp.13-19
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• 1992

This study were carried out to investigate the effective concentration of cryoprotective agents and sucrose by one-step straw method, and to determine the optimum thawing temperature and equilibration time of frozen porcine embryos. The porcine embryos foflowing dehydration by cryoprotective agents and a various concentration of sucrose were directly plunged into liquid nitrogen and thawed in 3$0^{\circ}C$ water. Survival rate was defined by FDA test. The results are sunnnarized as follows : 1. The survival rates of porcine embryos after ultrarapid frozen4hawing in the freezing medium with a various concentration of glycerol, DMSO and propanediol added 0.25M sucrose were higher survival rate than those of sucrose concentration of 0.50M. 2. The survival rates of porcine embryos after ultrarapid ftozen4hawing in the freezing medium added 0.25M and 0.SOM sucrose were higher survival rate than those of sucrose concentration of 0.75M and 1.00M. 3. The temperature thawed at 2$0^{\circ}C$ and 3$0^{\circ}C$ resulted in a significantly higher embryos survival rate after 72 hrs in culture than did at 35$^{\circ}C$. 4. The equilibration time on the survival rate of porcine embryos was attained after short period of time(2.5~5 min.) in the freezing medium higher than long period of time(10~20 min.).

• Journal of Institute of Convergence Technology
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• v.2 no.1
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• pp.1-6
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• 2012

The cold chain system in South-East Asia is requiring to maintain freshness of refrigerated or frozen food. In this study, Thermal storage system using Phase change material (PCM) was developed and evaluated its performance about temperature and cold keeping time. For various application of cold chain system, we developed portable cold box, cold roll container and freezing station. Keeping time on laboratory tests of portable cold box in case of refrigeration and freezing were 6 hours and 4 hours, respectively. Cold container was developed to 2.5 ton scale. Evaluation in Indonesia, it was showed to keep the setting temperature of $-10^{\circ}C$ over 40 hours at $30^{\circ}C$ of ambient air. Freezing station using PCM was kept over 24 hours under $-20^{\circ}C$.

• Food Science and Preservation
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• v.10 no.2
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• pp.125-130
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• 2003

This study was carried out to investigate the thermo-physical properties and design Freezing time prediction model from data of freezing test of Kimchi. Density of Kimchi were measured as 1001.9 ${\pm}$0.03 kg/㎥ at unfrozen state, 987.0 ${\pm}$0.07 kg/㎥ at frozen state and volume of the Kimchi expanded 4.67% at -l5$^{\circ}C$. Initial freezing point of Kimchi and seasoning were -4.0$^{\circ}C$ and -2.5$^{\circ}C$, respectively. Freezing ratio of Kimchi were estimated more than 50％ at -5.0$^{\circ}C$, more than 75% at -l0$^{\circ}C$ and approximately 90% at -25$^{\circ}C$. To obtain equation for freezing time prediction of Kimchi, freezing time(Y) was regressed against the reciprocal( $X_3$) of difference of initial freezing point and freezing medium temperature, reciprocal( $X_4$) of surface heat transfer coefficient, the initial temperature( $X_1$) and thickness( $X_2$) of samples. As results of the multiple regression analysis, equations were obtained as follows. Y$_{kimchi}$=3.856 $X_1$+13982.8 $X_2$+8305.166 $X_3$+ 3559.181 $X_4$-639.189( $R^2$=0.9632). These equations shown better results than previous models, and the accuracy of its was very high as average absolute difference of about 10% in the difference between the fitted and experimental results.

• Journal of Sensor Science and Technology
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• v.3 no.1
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• pp.61-67
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• 1994

In order to investigate the effects of heat treatment on the thermoelectric motive force (EMF) of type R thermocouples, the changes of EMF in the freezing points of aluminum and silver cells were measured with the immersion depth of themocouples. With the variation of heat treatment methods before use, it was found that the EMF values were different from each other, maximum $17.1{\mu}V$ at $660.323^{\circ}C$ and $18.1{\mu}V$ at $961.78^{\circ}C$. Additionally a thermocouple, which was not heat-treated fully, showed an EMF difference with the immersion depth even though it was located on the region maintained at the constant temperature. The measured differences were about maximum $7.8{\mu}V$ at the Al freezing point and $18.9{\mu}V$ at the Ag freezing point. It was recongnized that a thermocouple for the precise temperature measurement should be heat-treated carefully before service. In this report, the proper heat treatment methods for the type R thermocouple were given on the basis of the obtained experimental results.