• The Journal of Engineering Geology
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• v.14 no.4 s.41
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• pp.401-416
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• 2004

We have collected shale specimens from the Pungam Basin in Kangwon province and investigated change of physical properties by freezing and thawing in water as well as in acidic fluid. The temperature range was $-20{\pm}2^{\circ}C\~15{\pm}2^{\circ}C$. Specimens were frozen for 12 hours and thawed in water for 8 hours. Then, they were saturated in the vacuum chamber for 4 hours to make specimens fully saturated. This procedure was 1 cycle. We have measured absorption, ultrasonic velocity, shore hardness, slake durability and uniaxial compressive strength at every 5th cycles. The physical properties increased or decreased as freezing and thawing cycles increased. Uniaxial compressive strength decreased by 0.40MPa per cycle in water and by 0.48MPa in acidic fluid. Elastic constant also decreased by 0.21GPa per cycle in water and by 0.30GPa in acidic fluid. Absorption increased by $0.29\%$ and $0.37\%$ per cycle in water and acidic fluid, respectively. These results indicate that decrease in uniaxial compressive strength, elastic constant and absorption by freezing and thawing in acidic fluid is more rapid than in water. Ultrasonic velocities, shore hardness and slake durability show no differences in water and acidic fluid. When we compared our results with the temperatures in the Hongchon during the winter season, $6\~12$ cycles may be equivalent to 1 year.

• Food Science of Animal Resources
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• v.27 no.2
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• pp.190-196
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• 2007

This study was carried out to investigate the effects of pressure assisted freezing(PAF) on physicochemical properties of pork meat. Pork meat was frozen under pressure up to 200 MPa at $-60^{\circ}C$, and compared with fresh control. Phase transition temperature decreased with increasing pressure level, while pressure level had no effect on supercooling extent. Increasing pressure level increased pH of meat significantly(p<0.05). Thawing losses of all treatments were significantly higher(p<0.05) than control with the exception of PAF at 200 MPa. Water holding capacity(WHC) was increased significantly(p<0.05) with increasing pressure level up to 100 MPa. Cooking loss tended to decrease with increasing pressure level. In color, CIE $L^*-\;and\;b^*-value$ increased with increasing pressure level, while CIE $a^*-value$ decreased significantly(p<0.05). Increasing pressure level up to 150 MPa increased shear force significantly(p<0.05), however, no significant difference between 150 and 200 MPa in shear force was found(p>0.05). Therefore, the results indicated that excessive pressure level in PAF caused several losses in meat qualities, while PAF at mild pressure level improved meat qualities compared to atmosphere freezing.

• Magazine of the Korea Concrete Institute
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• v.10 no.4
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• pp.153-161
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• 1998

Concrete structures has been deteriorated by and freezing the thawing due to temperature gap. This study was conducted to evaluate durability of concrete which are increasingly demanded recently. Therefore the research of durability must be executed for application of waste foundry sand concrete real structures. Concrete durability properties incorporating waste foundry sand was performed with the variable of W/C ratio. Sand/Waste foundry sand ratio and Air entrainment-Non air entrainment. Cylinder specimens were made and subjected to freezing and thawing cycle at -18$^{\circ}C$ and 4$^{\circ}C$. Dynamic modulus of elasticity were evaluated as F/T cycle increase. The results show that strength of concrete is increased the W/C ratio decrease, the Sand/Waste foundry sand ratio increases when the concrete contains AE agent and decreasing W/C ratio and AE concrete makes improved resistance of freezing and thawing improved. Especially, resistance of freezing and thawing is improved by Fine aggregate/Waste foundry sand ratio which is 50%, 25%, 0% in a row. Therefore it is turn out the waste foundry sand could be applied to concrete from the experiment.

• Korean Journal of Agricultural and Forest Meteorology
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• v.14 no.4
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• pp.246-253
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• 2012

Despite frequent freezing injury to tea trees due low temperature, drought, and strong wind during wintertime, no comprehensive measurements have been taken. We selected and examined 9 locations in Hwagae-myeon and 4 places in Agyang-myeon, Hadong-gun, Gyeonsanggnam-do where low temperature damage had occurred between December 2010 and February 2011. Our objective is to examine the effect of frost damage on the morphological symptom and harvest of a tea tree exposed to a constant low temperature environment during wintertime. The results of our analyses on meteorological environment, tea leaf chromaticity, water content and trypan blue are as follows: (1) the number of days with temperature of $-10^{\circ}C$ or less, which were subject to frost damage to a tea tree were 8 and 13.6% during the winterization period in 2011; (2) the accumulated time was 1,308 minutes, and the longest duration at $-10^{\circ}C$ was 588 minutes from 21:08 p.m. 15 January to 7:30 a.m. $16^{th}$ January. The rainfall was only 104 mm which was 306 mm less than the previous year; (3) the lightness L values in 2011 were higher than in 2012 due to dehydration and necrosis by blue discoloration and red discoloration at all areas in chromaticity measurement; (4) the water content in a tea leaf in 2011 was higher than in 2012 due to low rainfall and strong wind, and almost no cell death phenomenon was observed from normal tea leaves subject to no low temperature stress in a trypan blue analysis; and (5) partial coloration due to cell death, however, took place in the leaves damaged by blue discoloration subject to low temperature stress, and most coloration due to cell death took place in the leaves damaged by red discoloration.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.9
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• pp.1307-1313
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• 2011

This study was conducted to evaluate the effects of irradiation temperature on the physicochemical and sensory properties of Tarakjuk, milk porridge. Tarakjuk was gamma-irradiated at different temperatures of $25^{\circ}C$ (in room), $4^{\circ}C$ (in ice), and $-20^{\circ}C$ (in dry ice) at a dose of 10 kGy, and then autoclaved at $120^{\circ}C$ for 15 min for comparison. pH and Hunter's color value of Tarakjuk were not changed by irradiation regardless of the temperature. However, the TBA (2-thiobarbituric acid) value decreased as irradiation temperature was decreased. The viscosity of Tarakjuk irradiated in dry ice was significantly higher than that irradiated at room temperature and in ice (p<0.05). For the sensory evaluation, there were no significant differences in overall acceptability between non-treated Tarakjuk and that irradiated in dry ice. Flavor pattern analysis using an electronic nose with a SAW (surface acoustic wave) sensor determined that the main peaks at retention times 3.88 and 7.34 sec were related with off-flavor induced by irradiation and unique flavor of Tarakjuk, respectively. These results indicated that irradiation at freezing temperature improved quality deterioration of Tarakjuk by gamma irradiation. However, sensory quality of Tarakjuk irradiated at freezing temperature was still lower than that of non-irradiated Tarakjuk. Therefore, further research is needed to improve the quality of Tarakjuk using combined treatment such as addition of antioxidants and vacuum packaging method.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.602-605
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• 2001

Low-temperature adaptation and protection for environmental stresses were studied in the gram-negative soil bacterium Bradyrhizobium japonicum 61A101c. B. japonicum was more resistant to alcohol, $H_2O_2$, heat and freezing following a pretreatment at $4^{\circ}C$, resulting in approximately 10 to 1,000 folds increased survival compared to mid-exponential-phase cells grown at an optimal temperature at $28^{\circ}C$. This phenomena relate to the cold shock protein expressed when cells are exposed to a downshift in temperature. To confirm the presence of cold shock protein genes in B. japonicum, a PCR strategy was employed using a degenerate primer set, which successfully amplified a putative csp gene fragment. Sequence analysis of the PCR product(200bp) revealed csp-like sequences that were up to 96% identical to csp gene of S. typhimurium.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.361-366
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• 2001

The purpose of installation of the brine heating system for LNG storage tank is the prevention of ground freezing. If the ground of LNG tank areas is frozen, it is caused by safety problems. The design of brine heating system for LNG storage tank which is constructing in our country is not well considered about domestic weather conditions and economical efficiency. Therefore, this paper reports on the study of the optimized temperature of inside pipes and cooling process through the transient analysis by using the existing brine heating system.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1663-1666
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• 2003

TMA clathrate that is used by PCM of ice storage system in this research creates hydrate crystallization at higher temperature than pure water, and application is expected as PCM because having comparative big dormant temperature without phase separation phenomenon. In case this research uses TMA clathrate by PCM, choose admixture by purpose to control or remove subcooling of TMA clathrate and evaluated experimentally. Subcooling is improved and can expect contraction of freezing machine running time and increase of coefficient of performance as that add admixture to TMA clathrate conclusively. Also, may supply thermal storage system that apply low temperature potential heat thermal storage material that subcooling is improved more extensively laying stress on medium size building and small size building, can expect allowance through localization of ice storage system.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.10a
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• pp.150-151
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• 2016

In previous study, researchers studied development of early anti-freezing cement at low temperature (-5℃) using hydration characteristics of reduction slag. In this study, the durability of concrete using reduction slag was conducted. The experiment result, reduction slag makes high temperature and improves compressive strength due to quick setting. And then result of durability show that it is no problem. However, it is considered that further study is needed about high shrinkages which was indicated in dry shrinkage.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.10a
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• pp.152-153
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• 2016

In this research, we evaluate the performance for preventing frost damage at early age of mortar using variable cement and self-heating binder. Purpose of final research is preventing freezing and thawing by making the compressive strength 5MPa in 3days below zero temperature without heat curing. We compare the compressive strength of mortar and concrete using variable cements and self-heating binder in low temperature.