• Magazine of the Korea Concrete Institute
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• v.10 no.4
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• pp.205-212
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• 1998

Frost damage of a storage tank for chemical admixtures caused by a low temperature in winter and quality deterioration of chemical admixtures have been often reported. However, there have been few regulations and researches related to the frost damage of chemical admixtures and facilities. Therefore, this paper is intend to investigate not only, the freezing points of chemical admixtures such as AE admixtures and water-reducing AE admixtures, etc., but also the quality variation of concrete used with chemical admixtures before freezing and after freeze-thaw cycles. According to the results of experiments, most chemical admixtures except anti-freezing agent and accelerating water-reducing AE admixtures should be kept from being frozen in low winter temperatures. However, full agitation of frozen chemical admixtures dose not cause the problems of concrete related to the quality of chemical admixtures.

• The Journal of Engineering Geology
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• v.31 no.3
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• pp.257-267
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• 2021

Constraints on the structure and composition of the active layer are important for understanding permafrost evolution. Soil convection owing to repeated moisture-induced freeze-thaw cycles within the active layer promotes the formation of self-organized patterned ground. Here we present the results of ground penetrating radar (GPR) surveys across a selected sorted circle near King Sejong Station, Antarctica, to better delineate the active layer and its relation to the observed patterned ground structure. We acquire GPR data in both bistatic mode (common mid-points) for precise velocity constraints and monostatic mode (common-offset) for subsurface imaging. Reflections are derived from the active layer-permafrost boundary, organic layer-weathered soil boundary within the active layer, and frozen rock-fracture-filled ice boundary within the permafrost. The base of the imaged sorted circle possesses a convex-down shape in the central silty zone, which is typical for the pattern associated with convection-like soil motion within the active layer. The boundary between the central fine-silty domain and coarse-grained stone border is effectively identified in a radar amplitude contour at the assumed active layer depth, and is further examined in the frequency spectra of the near- and far-offset traces. The far-offset traces and the traces from the lower frequency components dominant on the far-offset traces would be associated with rapid absorption of higher frequency radiowave due to the voids in gravel-rich zone. The presented correlation strategies for analyzing very shallow, thin-layered GPR reflection data can potentially be applied to the various types of patterned ground, particularly for acquiring time-lapse imaging, when electric resistivity tomography is incorporated into the analysis.

• Journal of the Korean Geosynthetics Society
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• v.10 no.2
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• pp.73-79
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• 2011

Based on the results of Part 1 of our two-parts paper, the possibility on field applicability of CMDS(Coal Mine Drainage Sludge) mixed with bentonite and cement as a liner in landfill sites was investigated. The optimum moisture content that met the landfill liner condition was obtained when the ratio of CMDS: bentonite: cement was 1: 0.5: 0.3 in a lab-scale. The relative compaction was measured in 90.1%, which results for construction field have been generally acceptable. In this study, a large-scale Lysimeter($1.0m{\times}1.5m{\times}2.0m$) was used to simulate the effects of the layer on the freeze/thaw by -20 average temperature. The mixture after freezing/thawing showed compressive strength more than $5kg/cm^2$, which was satisfied with EPA standards. Initial permeability of CMDS was $7.10{\times}10^{-7}cm/s$ and permeability its mixture after freezing/thawing was increased to $9.80{\times}10^{-7}cm/s$. The change of temperature in the layers rises and falls with linear and temperature gradient keep maintain the present state. Moisture contents in the layers have not been radically changed. Through the leaching test determined by KSLT method, it was found that heavy metals excluding Zn and Ni were not leached out or leached out less than the standards during 7 cycles of freezing/thawing process. Since it shows the increased permeability about 1.5 times and slight change in moisture content, but it was satisfied with EPA standar through 7 cycles of freezing/thawing process, this mixture can be applied as a liner in landfill final cover system.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.12
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• pp.2019-2027
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• 2013

In this study, we tried to develop a coating agent for the fresh-cut fruits used in cakes. First, the coating agent mixing ratios of sugar, pectin, sodium alginate, carrageenan, xanthan gum, vitamin C, and purified water were selected to be 55, 2, 2, 0.04, 0.1, 0.05, and 40.81% (w/w), respectively. In a freeze-thaw stability of the coating agent, the viscosity remained constant for 3 cycles of freezing and thawing repetition process, but showed a slightly decreasing trend in the 4th repetition process (P<0.05). On the other hand, the sugar content, pH, and chromaticity remained constant even in the 4th repetition process. Pineapple coated with the coating agent had smaller weight loss, hardness changes, and total bacteria distribution compared to the uncoated pineapple (P<0.05). In the chromaticity, both of the two pineapples experienced browning with increasing storage duration, as L value decreases and b value increases. However, when the color difference was compared, the progress of browning for the uncoated pineapple was faster than the coated pineapple. Also, the progress of browning at $4^{\circ}C$ was found to be slower than the progress of browning at $25^{\circ}C$. Therefore, the storage stability of the fresh-cut fruits could be improved by coating the fresh-cut fruits for cakes with the coating agent and storing at a low temperature, which would contribute to extending the shelf-life of cakes.

• Clinical and Experimental Reproductive Medicine
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• v.39 no.1
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• pp.33-39
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• 2012

Objective: We devised a novel strategy, a GnRH antagonist protocol with a GnRH agonist trigger followed by frozen-thawed blastocyst transfers with long zona dissection (LZD). The purpose of this study was to investigate the clinical outcomes of this new strategy according to age. Methods: Ninety women aged less than 35 (group A) and 32 women aged 35 to 39 (group B) underwent the GnRH antagonist protocol with a GnRH agonist trigger in order to obtain many oocytes and prevent early-onset ovarian hyperstimulation syndrome (OHSS). All oocytes were cultured to the blastocyst stage and all blastocysts grade 3BB or better were cryopreserved. Embryo transfers were only performed in freeze-thaw cycles to prevent late-onset OHSS and to overcome embryo-endometrium dyssynchrony. LZD was performed just after thawing to improve hatching and implantation rates. Results: The average numbers of retrieved oocytes and blastocysts grade 3BB or better were $12.8{\pm}5.5$ and $4.4{\pm}2.6$ in group A and $10.9{\pm}7.4$ and $2.5{\pm}2.2$ in group B, respectively, and OHSS did not occur in any of the women. Implantation rates were 46.7% in group A and 39.3% in group B. Cumulative clinical pregnancy rates per retrieval were 77.8% in group A and 62.5% in group B. Cumulative ongoing pregnancy rates per retrieval were 71.1% in group A and 53.1% in group B. Conclusion: GnRH antagonist protocol with GnRH agonist trigger followed by frozen-thawed blastocyst transfers with LZD can generate many blastocysts without OHSS and maximize cumulative pregnancy rates per retrieval. This strategy is more effective in young women aged less than 35 than in women aged 35 to 39.

• Journal of Pharmaceutical Investigation
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• v.36 no.2
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• pp.89-95
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• 2006

A selective and sensitive reversed-phase HPLC method for the determination of pentoxifylline in human serum was developed, validated, and applied to the pharmacokinetic study of pentoxifylline. Pentoxifylline and internal standard, chloramphenicol, were extracted from the serum by liquid-liquid extraction with dichloromethane and analyzed on a Luna CI8(2) column with the mobile phase of acetonitrile-0.034 M phosphoric acid (25:75, v/v, adjusted to pH 4.0 with 10 M NaOH). Detection wavelength of 273 nm and flow rate of 0.8 mL/min were used. This method showed linear response over the concentration range of 10-500 ng/mL with correlation coefficients greater than 0.999. The lower limit of quantification using 0.5 mL of the serum was 10 ng/mL, which was sensitive enough for pharmacokinetic studies of pentoxifylline. The overall accuracy of the quality control samples ranged from 89.3 to 92.7% for pentoxifylline with overall precision (% C.V.) being 4.1-9.2%. The relative mean recovery of pentoxifylline for human serum was 105.8%. Stability (stock solution, short and long-term) studies showed that pentoxifylline was not stable during storage. But three freeze-thaw cycles and extracted serum samples were stable. This method showed good ruggedness (within 15% C.V.) and was successfully applied for the analysis of pentoxifylline in human serum samples for the pharmacokinetic studies of orally administered $Trental^{\circledR}$ tablet (400 mg pentoxifylline), demonstrating the suitability of the method.

• Journal of the Korean Geographical Society
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• v.41 no.6 s.117
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• pp.657-669
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• 2006

Rates and processes of bare patch denudation were observed at Janggumokoreum(1,710m) and Minoruem(1,600m) in order to clarify some characteristics of turf exfoliation in the subalpine grassland of Mt. Halla. The bare patches have marginal terrace fronts with a maximum height of 85 cm. The terrace risers usually develop an overhanging edge 2 to 38 cm long that eventually hangs down and protects the riser beneath. The patches are largely covered with angular pebbles and cobbles. The mean rate of riser retreat for the period 2002-2004 is 39.2 mm, equivalent to 19.6 mm/yr. However, there is a disparity of the rate of riser retreat at individual sites. The maximum rate is 131 mm measured at Janggumokoreum patch while the minimum rate is 0 mm at Minoreum patch. The rate of riser retreat also varies with seasons. The thawing season of April exhibits a maximum rate of retreat. The freezing season of October and November and the rainy season of June and July show relatively high rates of retreat. Several Processes such as frost action, aeolian deflation, rainwash, rainsplash and fauna activity cause the denudation of bare patches. In particular, the needle ire action which is combined with rainwash or deflation plays a primary role in turf exfoliation due to the diurnal freeze-thaw cycles occurred over 100 days, melted snow and strong wind in the subalpine zone of Mt. Halla. Rainwash is also an important contributing process in the rainy season because Mt. Halla has the highest precipitation in Korea. By contrast, rainsplash erosion has a minor effect on the bare patch denudation due to the overhanging edge of terrace risers. Recent increase in roe deer appears to be responsible for turf destruction.

• Journal of fish pathology
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• v.22 no.3
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• pp.335-342
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• 2009

The stability of immunoglobulin M (IgM) on different serum storage conditions and specific antibody response were tested using the serum collected from sevenband grouper Epinephelus septemfasciatus by enzyme-linked immunosorbent assay (ELISA). To test the effect of storage temperature and duration, sevenband grouper antiserum against bovine serum albumin (BSA) was stored at -80, -20 or 4${^{\circ}C}$ for 1, 34, 61 or 119 days. In addition, to test the effect of repeated freeze-thawing condition, the anti-BSA fish serum was frozen at -20 and -80${^{\circ}C}$ and then thawn and frozen for 1, 5 or 10 times repeatedly. Consequently, no significant difference was found in ELISA optical density (O.D.) values of sera for the above mentioned storage conditions: different temperatures (-80, -20 and 4${^{\circ}C}$), durations of storage (1, 34, 61 and 119 days), and repeated thaw-freeze cycles (1, 5, and 10 times), indicating that IgMs of test fish were stable. The specific antibody response of sevenband grouper was observed after BSA-immunization of the test fish reared at 20 ${^{\circ}C}$ or 25${^{\circ}C}$. At the rearing temperature of 20${^{\circ}C}$, the specific antibody against BSA first appeared at 14 days and maximum antibody titer was observed between 21 and 28 days, while at the rearing temperature of 25 ${^{\circ}C}$, specific antibody appeared at 7 days and maximum antibody titer was observed between 14 and 21 days. In conclusion, the rearing temperature at 25${^{\circ}C}$ gave a faster and higher specific antibody response than at 20${^{\circ}C}$ and the specific antibody response maintained for approximately 2 months at 20℃ and 25${^{\circ}C}$.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.9
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• pp.251-258
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• 2020

This study investigated the effect of Zardaverine supplementation in freezing extender, on kinetic characteristics of post-thawed boar sperm. Cryopreservation of boar sperm is an important technique of assisted reproductive technology and genetic resource banking. Although this technique is particularly useful, freeze-thaw cycles associated with sperm cryopreservation significantly reduce sperm quality. Semen from mature Duroc boars were collected and cryopreserved in freezing extenders (LEY) treated with varying concentrations of Zardaverine (0, 20, 50, 75, 100 𝜇M). The time-dependent kinetic characteristics of post-thawed spermatozoa were determined after thawing by applying computer-assisted sperm analysis (CASA). We observed that the motility immediately after thawing was significantly higher in 20 𝜇M stocks than in control (0 𝜇M) and the other treatments (p<0.05). Curvilinear velocity (VCL) in 0 𝜇M and 20 𝜇M stocks were significantly higher than the other treatment groups, except 75 𝜇M (p<0.05). Higher average path velocity (VAP) was obtained at 20 𝜇M as compared to 100 𝜇M, whereas amplitude of head lateral displacement (ALH) was significantly higher at 20 𝜇M than 50 𝜇M and 100 𝜇M (p<0.05). No differences were obtained for Straight-line velocity (VSL) and Linearity (LIN). In conclusion, our results indicate that Zardaverine improves the motility, VCL, VAP, and ALH of post-thawed boar sperm.

• Journal of Embryo Transfer
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• v.32 no.1
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• pp.1-8
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• 2017

Cryopreservation of germ cells from genetically proven animals could be a source of restoration tools from the risk of extinction or disappearance of wanted characteristics. Using frozen semen, the genetic gains of Korean native cattle have been increased greatly for 70 years. The preservation of genetic resources as a form of frozen semen straw has limited availability due to the numbers. To circumvent this weakness of frozen semen, we tested two re-freezing methods with different initial thawing temperatures using frozen Korean proven semen and rare breed semen from albino, black and chikso breeders. It has been known that human sperm could resist to cryo-damages by repeated freeze-thaw cycles, but not for Korean proven bulls number (KPN) or for rare breeds. Total 7 frozen semem from brindled(2), black(1), Korean Albino(2) and KPN(1) bulls were used for our research. After thawing straws under $5^{\circ}C/2min$ or $37^{\circ}C/40sec$ with low temperature water bath and thermo jug, spermatozoa were re-diluted with triladyl diluents after first thawing and re-frozen. Sperm motilities were compared between animals and treated groups after re-thawing. Mean values of motility and viability of refrozen/thawed sperm for expansion of the number of straws were significantly higher in $5^{\circ}C$ than in $37^{\circ}C$ (P < 0.05). However, the activity of viable sperm thawed at $5^{\circ}C$ was significantly decreased before refreezing. It is estimated that re-freezing of frozen semen from rare Korean native cattle is possible with resistant properties of survived spermatozoa.