• Korean Journal of Animal Reproduction
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• v.25 no.4
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• pp.371-379
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• 2001

The objective of this study was to establish an effective cryopreservation method of in vitro-produced bovine embryos. For the vitrification, in virtro-produced embryos at 8-cell, morula and blastocyst stages were exposed to freezing solution containing 5.5 M EG (EG 5.5) for 20 sec, loaded on each containers such as EM grid, OPS and Cryo-loop, and then immediately plunged into liquid nitrogen at -196$^{\circ}C$. Thawed embryos were serially diluted in 0.5, 0.25 and 0.125 M sucrose in m-HPBS, each for 1 min, and cultured in CRlaa medium supplemented with 10% FBS. Significant differences in the rates of re-expanded and hatched embryos were not observed among these embryo containers. The total cell number of expanded blastocyst cultured in vitro after vitrification was examined by Hoechst staining. There were no differences between non-vitrified (180.0 $\pm$ 5.4) and vitrified groups (178.0 $\pm$ 7.5). In addition, when the cellular injuries after vitrification were compared by double staining. There were no significant difference in the ratio of live and dead cells between non-vitrified group (176 : 4) and vitrified group (172 : 6). Therefore, these results suggest that bovine embryos can be cryopreserved easily, effectively and successfully by vitrification using various containers, such as EM grid, OPS or Cryo-loop in the presence of EG 5.5 freezing solution.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.5
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• pp.607-616
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• 2022

Corrosion and degradation of reinforced structures due to abnormal climates and natural disasters further accelerate the aging of structures. Coping with the decrease in structure performance, many old structures are being repaired and reinforced with low-weight and high-strength materials such as glass fiber composite material (GFRP). To further contribute, this paper focus on a more economical and eco-friendly material, basalt fiber composite (BFRP), which provide a more effective lateral constraint effect for seismic reinforcement. The main variables considered in this study are the curing temperature during the manufacturing of BFRP and the material characteristics of the target concrete member. The lateral constraint reinforcement effect was investigated through the evaluation of the performance of normal concrete and those with improved durability through fiber reinforcement. The reinforcement effect was 3.15 times for normal concrete and 3.72 times for fiber reinforced concrete, and the difference in reinforcement effect due to the improvement of the durability characteristics of the compression member was not significant. Lastly, the performance of the BFRP was compared with the results of the GFRP reinforcement from the previous study. The effect of the BFRP reinforcement was 1.18 times better than that of the GFRP reinforcement.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.4
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• pp.482-488
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• 2022

In this study, the durability of ultra rapid hardening mortar for sewage pipe was evaluated by type of mortar binder. As a result of analyzing the internal structure for each type of mortar, it was confirmed that Al₂(OH)₃ was generated in the internal structure of the CAC-based mortar, and its corrosion resistance was superior to that of other types of mortar. As a result of the compressive strength test, OPC had the tsmallest strength, followed by CAC100 > CAC100P > CAC80. This trend was similar to the previous study results. Chloride ion penetration resistance and freeze-thaw test showed similar trends. That is, CAC and C12A7 were better than OPC, and CSA was worse than OPC. This is mostly beacuse of cracks caused by expansion of CSA-based mortar. CAC100P mix showed the best chemical resistance. It is thought that this is because the alumina gel formed inside the mortar and the polymer combine to make the internal structure more dense.

• Economic and Environmental Geology
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• v.56 no.1
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• pp.103-114
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• 2023

The Christian Museum of Gongju Jeil Church was first built in 1931 and was largely damaged during the Korean War, but the walls and chimneys have been preserved. This building has a high architectural values in that the chapel was reconstructed in 1956, and maintains its original form through repair of damaged parts rather than new construction. The stained glass windows were as installed in 1979 and has a great significance in the Dalle de Verre method using lump glass. However, some of the stained glass damaged partially, such as various cracks and splits, and vertical and horizontal cracks in the joint fillers of supporting the colored glass. As the structural materials of the stained glass window, an iron frame and cement mortar filled with it were used, and corrosion of iron, cracking of mortar and granular decomposition appear partially due to weathering. In the joint fillers, the content of Ca and S is very high, indicating that gypsum were used as admixtures, and the gypsums grow in a rhombohedral and forms a bundle, which is investigated to have undergone recrystallization. As a result of modeling the ultrasonic velocity at the joint fillers, the left and right windows at the entrance show relatively weak in the range of 800 to 1,600m/s, and the lower right corner of the altar window and the upper left corner of the center window were also 1,000 to 1,800m/s, showing relatively low physical properties. And gypsums produced during the neutralization of lime mortar were detected in the joint fillers and contaminants on the surface. Such salts may cause damage to the joint material due to freezing and thawing, so appropriate preventive conservation is required. Also, since various damage types are complexly appearing in stained glass window and joint filler, customized conservation treatment should be reviewed through clinical tests.

• Tunnel and Underground Space
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• v.17 no.4
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• pp.266-284
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• 2007

Recently, many efforts have been made to construct the first unlined tunnel, without in-situ concrete lining, in Korea. However, the lack of reliability in the performance of shotcrete as permanent tunnel support prevented from its realization. Shotcrete has been regarded to have significant problems in field application and long term performance because of unsatisfactory strength level and durability compared to those of European countries. In this study, the high strength shotcrete satisfying compressive strength over 40 MPa and flexural strength over 4.5 MPa was developed from optimized mix design. The type of accelerators and the amount of silica fume were selected as the main factors in mixing process and the analyses were carried out up to the elapsed time of 2 years. In order to evaluate the short term durability of shotcrete, an array of laboratory test consisting of freeze-thaw, carbonation chloride penetration and permeability test was performed. For long-term durability tests, specimens have been put in an operated highway tunnel to expose them to the similar environment when they are actually used as an unlined tunnel support. From the strength and durability tests, it was found that only alkali-free based accelerator satisfied the target strength of this study and also, the developed shotcrete showed very high performance in its durability.

• Journal of the Korean Geosynthetics Society
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• v.10 no.2
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• pp.67-72
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• 2011

CMDS (Coal Mine Drainage Sludge) is mainly generated from acid mine drainage during physicochemical treatment or electrical purification. CMDS is well worth considering on recycling possibilities in various areas. This research applies the liner and cover materials using waste disposal landfill generally to treat acid mine drainage sludge. In this Part I of the two parts paper, physico-chemical characteristics of CMDS, bentonite and cement to prepare the liner have been identified using XRD, XRF, FESEM. In addition, combining their physicochemical characteristics, the optimum mixing ratio has been determined to be 1: 0.5: 0.3 for CMDS: bentonite: cement by the batch tests. Initial permeability of CMDS was $7.10{\times}10^{-7}cm/s$. Through the leaching test, it was confirmed that its mixture was environmentally safe. In the Part 2, a large-scale Lysimeter was used to simulate the effects of the layer on the freeze/thaw for evaluation on field applicability and stability.

• Childhood Kidney Diseases
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• v.14 no.2
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• pp.132-142
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• 2010

Hypokalemia usually reflects total body potassium deficiency, but less commonly results from transcellular potassium redistribution with normal body potassium stores. The differential diagnosis of hypokalemia includes pseudohypokalemia, cellular potassium redistribution, inadequate potassium intake, excessive cutaneous or gastrointestinal potassium loss, and renal potassium wasting. To discriminate excessive renal from extrarenal potassium losses as a cause for hypokalemia, urine potassium concentration or TTKG should be measured. Decreased values are indicative of extrarenal losses or inadequate intake. In contrast, excessive renal potassium losses are expected with increased values. Renal potassium wasting with normal or low blood pressure suggests hypokalemia associated with acidosis, vomiting, tubular disorders or increased renal potassium secretion. In hypokalemia associated with hypertension, plasam renin and aldosterone should be measured to differentiated among hyperreninemic hyperaldosteronism, primary hyperaldosteronism, and mineralocorticoid excess other than aldosterone or target organ activation. Hypokalemia may manifest as weakness, seizure, myalgia, rhabdomyolysis, constipation, ileus, arrhythmia, paresthesias, etc. Therapy for hypokalemia consists of treatment of underlying disease and potassium supplementation. The evaluation of hyperkalemia is also a multistep process. The differential diagnosis of hyperkalemia includes pseudohypokalemia, redistribution, and true hyperkalemia. True hyperkalemia associated with decreased glomerular filtration rate is associated with renal failure or increased body potassium contents. When glomerular filtration rate is above 15 mL/min/$1.73m^2$, plasma renin and aldosterone must be measured to differentiate hyporeninemic hypoaldosteronism, primary aldosteronism, disturbance of aldosterone action or target organ dysfunction. Hyperkalemia can cause arrhythmia, paresthesias, fatigue, etc. Therapy for hyperkalemia consists of administration of calcium gluconate, insulin, beta2 agonist, bicarbonate, furosemide, resin and dialysis. Potassium intake must be restricted and associated drugs should be withdrawn.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.6
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• pp.29-36
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• 2015

In this study, to examine the use of sulfur polymer as a coating agent for concrete, durability and hazard evaluations were performed. The result of the evaluation indicated that the chemical resistance of the coating agent for concrete was outstanding against acidic, base, and alkaline solutions. The evaluation of the bond strength after an accelerated weathering test depending on the mixing condition indicated that the most outstanding strength characteristic was obtained when silica powder and fly ash were mixed at the same time. The bond strength exceeded 1 MPa in every mixing condition even after the repeated hot and cold treatment of the coating agent specimen for concrete, and the SFS mix proportion showed the highest bond strength. The examination of the accelerated carbonation and chloride ion penetration resistance of the concrete coated with the coating agent indicated that the specimen coated with the coating agent using silica powder as a filler showed the most outstanding durability. When a fish toxicity test was performed to examine the hazard of the use of the functional polymer as a coating agent for concrete, the functional polymer was found to have no effect on the organisms. When the chemical resistance, freezing and thawing resistance, carbonation, and chloride ion penetration resistance of the coating agent were considered, substituting silica powder and fly ash as the fillers of the functional polymer by 20%, respectively, was the optimal level in the range of this study.

• Journal of the Korean Geotechnical Society
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• v.16 no.1
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• pp.179-189
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• 2000

The purpose of this research is to complement the existing researches on landfill bottom liners behavior during the periods of freeze and thaw. Landfill-related researches have been typically focused on small-scale soil samples that are often compacted under conditions different from those used in the field. Although these tests have been invaluable in clarifying the problem of freeze and thaw, extending the results of such experimental studies to prototype landfills are questionable. In this investigation, the author utilized a large scale laboratory simulation allowing inclusion of the field depth of the cover systems, layered soil profiles, rainfall simulation, a cold climate and boundary conditions similar to those encountered in the landfill. The soil materials were stabilized soils (mixed clays, cements, and minerals) instead of clays. The bottom liners are made up of drainage layer (30 cm), stabilized layer (75 cm), and leach collection layer (60 cm). The stabilized layers are made up of supporting layer (45 cm) and low permeable layer (30 cm) - consisting of $P_A\; and\; P_B$ layer. As a results, depths of penetration increased by about 2~5 more centimeters at rainfall simulated designs than those at no rainfall simulated designs (that is design 3, design 5 and design 7) - it increased by about 20mm/day in the bottom liners and frost heaves also increased it by a few millimeters. Also, a few cracks appeared partly. According to these results, we can surmise that the compacted stabilized soil is more reliable than the compacted clay liners for construction of the landfill liners.

• Journal of The Korean Society of Clinical Toxicology
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• v.1 no.1
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• pp.27-33
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• 2003

Purpose: According as the accessibility about drugs becomes various, the occurrence of drug intoxication is increasing. Since report that doxylamine causes rhabdomyolysis often, drug-induced rhabdomyolysis is one of the most important complications in patients with drug intoxication. Acute renal failure (ARF)'s availability is important to the management in rhabdomyolysis, but report about rhabdomyolysis or ARF occurrence for whole intoxicated drugs is lacking up to now. Methods: This research did to 61 patient who had rhabdomyolysis of drug intoxication. First, object patients were divided into two gruops: doxylamine-ingested (Group I) vs non-doxylamine ingested (Group II). And then we analyzed on the early patient's clinical events and laboratory data. We used ROC curve to recognize'the early clinical factors that could forecast ARF appearance among these patients in addition. Results: Almost rhabdomyolysis was happened by doxylamine in drug intoxication ($55.7\%$). However, as compared to group II, group I showed better clinical course, lesser ARF occurrence and hemodialysis requirement. In group II, time was longer in hospital reaching from intoxication, the ARF occurrence rate was higher ($52.6\%$). Analyzing the ROC curve to useful initial factors, they were creatinine, uric acid and interval time from ingestion to hospital. These cut-off values were 1.44 mg/dL, 6.8 mg/dL and 5 hrs. Sensitivity for ARF estimate was $100\%$, specificity $69-98\%$. Conclusion: Compared to group II, Doxylamine-ingested group showed good clinical course. Creatinine, uric acid, interval time from ingestion to hospital aided in ARF estimate in drug-induced rhabdomyolysis.