• 방사성폐기물학회지
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• 제19권3호
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• pp.289-295
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• 2021

A laser scabbling experiment was performed using a high-power fiber laser to investigate the removal rate of the concrete block and the scabbled depth. Concrete specimens with a 28-day compressive strength of 30 MPa were used in this study. Initially, we conducted the scabbling experiment under a stationary laser beam condition to determine the optimum scan speed. The laser interaction time with the concrete surface varied between 3 s and 40 s. The degree of spalling and vitrification on the surface was primarily dependent on the laser interaction time and beam power. Furthermore, thermal images were captured to investigate the spatial and temporal distribution of temperature during the scabbling process. Based on the experimental results, the scan speed at which the optical head moved over the concrete was set to be 300 mm·min^-1 or 600 mm·min^-1 for the 4.8-kW or 6.8-kW laser beam, respectively. The spalling rates and average depth on the concrete blocks were measured to be 87 cm³·min^-1 or 227 cm³·min^-1 and 6.9 mm or 9.8 mm with the 4.8-kW or 6.8-kW laser beams, respectively.

• 대한수의학회지
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• 제42권1호
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• pp.35-43
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• 2002

Cryopreservation is commonly used for an efficient utilization of semen, oocytes and embryos but has disadvantage in the survival, development of the post-thawed eggs. The high risk in the survival, development of eggs after thawing is thought to be caused by inappropriate internal regulation of $Ca^{2+}$ and/or formation of intracellular ice crystals. In this experiment, we tested whether the $Ca^{2+}$ current (iCa), a decisive factor to $Ca^{2+}$ entry, was altered in post-thawed oocytes by using whole cell voltage clamp technique. The quality and survival rates of the oocytes derived from both fresh and frozen groups were examined by morphology and FDA-test. Vitrified oocytes (VOs) were incubated for 4 hr after thawing and then donated to this experiment. Ethyleneglycol-ficoll-galactose (EFG) was used as a cryoprotectant for vitrification. The membrane potential was held at -80 mV and step depolarizations of 250 ms were applied from -50 mV to 50 mV in 10 mV increments. The survival rates showed a higher in VOs vitrified with EFG containing $Ca^{2+}$ than in VOs vitrified with EFG under the $Ca^{2+}$-free condition (82.0% vs 14%). In group with/without $Ca^{2+}$, the survival rates were significantly (P<0.01) difference. In the fresh metaphase II oocytes (FOs), current-voltage (I-V) relationship showed that iCa began to activate at -40 mV and reached its maximum at -10 mV. With same voltage pulses, inward currents were elicited in VOs. I-V relationships observed in VOs were similar to those in FOs. Time constants of activation and inactivation of the inward current shown in VOs were not different to those in FOs. This accordance in I-V relations and time constants in FOs with those in VOs indicates that the inward currents in FOs are unaltered by vitrification and thawing. Therefore, vitrification with EFG does not play as a factor to deteriorate $Ca^{2+}$ entry across the membrane of the oocytes.

• Integrative Medicine Research
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• 제6권1호
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• pp.12-18
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• 2017

Cryopreservation is a process that preserves organelles, cells, tissues, or any other biological constructs by cooling the samples to very low temperatures. The responses of living cells to ice formation are of theoretical interest and practical relevance. Stem cells and other viable tissues, which have great potential for use in basic research as well as for many medical applications, cannot be stored with simple cooling or freezing for a long time because ice crystal formation, osmotic shock, and membrane damage during freezing and thawing will cause cell death. The successful cryopreservation of cells and tissues has been gradually increasing in recent years, with the use of cryoprotective agents and temperature control equipment. Continuous understanding of the physical and chemical properties that occur in the freezing and thawing cycle will be necessary for the successful cryopreservation of cells or tissues and their clinical applications. In this review, we briefly address representative cryopreservation processes, such as slow freezing and vitrification, and the available cryoprotective agents. In addition, some adverse effects of cryopreservation are mentioned.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2001년도 춘계학술발표대회 논문집
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• pp.110-113
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• 2001

Dielectrometry has been used to monitor the cure of epoxy resin using composite matrix. In this investigation, physical properties of the mixture of epoxy resin(LY564), bisphenol A type, and cycloaliphatic hardener(HY 2954) were observed. Activation energy at maximum tan $\delta$ and gelation point was determined during isothermal scanning. From IonViscosity data, it was found that vitrification peak after gelation was appeared on slow heating rate. It was also measured that the duration time for full cure was necessary and it was about 24 hr at $145^{\circ}C$. Therefore, epoxy resin used in this research is required the extended time for full cure.

• 한국수정란이식학회지
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• 제19권1호
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• pp.35-42
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• 2004

본 연구는 돼지 배아의 유리화 동결 시 CB 처리군과 CB 비처리군의 영향을 비교하였다. CB의 농도별, 처리 시간별로 처리한 뒤 유리화 동결 융해 후 정상적인 형태 회수율과 생존률을 각각 조사하였다. 1. CB를 전 처리한 군과 비처리군의 정상적인 형태율이 각각 84.2%, 81.9%로 유의한 차이가 없었으나, 융해 후 72시간 째 생존률의 결과에서는 각각 60.5%, 32.8%로 유의성(p<0.1)이 검증되었다. 2. CB 농도별 생존률에 미치는 영향은 7.5 $\mu\textrm{g}$/$m\ell$의 처리군이 다른 처리군에 비하여 유의적으로 높았다(p<0.05). 정상 형태율 95%와 융해 후 생존률 73%로서 다른 농도에 비하여 65∼76%, 15∼57%보다 각각 높았다. 3. 7.5 $\mu\textrm{g}$/$m\ell$ 농도의 CB 전처리의 처리 시간에 따른 영향은 20분 처리하였을 때 정상적인 형태율은 81%로 다른 처리군(25∼69%)보다 높았고, 24시간 째 생존률의 결과로도 64%, 6∼56%로 유의적인 차이는 나타나지 않았다. 또한 원심 처리군과 비처리군에서도 CB를 20분으로 처리하였을 때 가장 좋은 결과를 나타내었으며, 원심 비처리군보다는 원심 처리군이 좀 더 높은 결과를 보여 주었다.

• Journal of Animal Science and Technology
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• 제49권2호
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• pp.287-294
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• 2007

성판별을 위한 biopsy 후 수정란의 발달율 및 동결－융해 후의 생존율 조사는 다음과 같다. 한우 체내 및 체외 수정란의 성판별을 위해서 영양막 세포의 일부를 채취하기 위해서 수정란을 biopsy 하였다. biopsy된 수정란의 생존율 조사의 결과는 체내 수정란이 100% 그리고 체외수정란이 90.0%의 결과를 나타내어 체내 수정란이 체외 수정란 보다 biopsy 후의 생존율이 높게 나타났음을 알 수 있었다. 수정란의 성판별 비율은 체내 수정란에서는 암컷과 수컷의 비율이 46.3%와 53.7%로 각각 나타나 수컷의 비율이 암컷 보다 다소 높은 경향을 보였으며, 체외 수정란에 있어서는 암컷과 수컷의 비율은 40.0% 와 60.0%로 수컷의 비율이 높게 나타났으나 유의적인 차이는 보이지 않았다. 성판별된 수정란의 동결－융해 후 생존성은 완만동결 방법에 의한 수정란의 생존율은 체내 수정란에서 58.8 %, 체외 수정란에서는 41.7% 그리고 초자화동결 방법에서는 체내 수정란의 생존율이 77.8%, 체외 수정란은 57.1%로의 결과를 보여 체내 수정란을 이용한 초자화동결 방법에서 상대적으로 더 높은 생존율을 보였다.

• Clinical and Experimental Reproductive Medicine
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• 제30권3호
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• pp.241-248
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• 2003

Objective: The purpose of this study was to evaluate the survival rate of vitrified blastocyst according to the freezing vessels, equilibration time in cryoprotectant and artificial dehydration method. Methods: Human blastocysts were vitrified after loading onto the plastic straw, open-pulled straw (OPS), electron microscopy grid (EM grid) for 1.5 min or 3 min. They also were directly plunged into LN2 within 30sec. For artificial shrinkage of blastocysts, 36 gauge fine needle was pushed at the cellular junction of the trophectoderm into the blstocoele cavity until it shrank without damage of inner cell mass. Results: The survival rate of vitrified blastocysts on plastic straw, OPS, EM grid as freezing vessels were 26.7, 13.0 and 60.5%, respectively. The survival rate of EM grid was significantly higher than that of plastic straw and OPS (p<0.05). For 1.5 min equilibrium, the survival rates of early blastocyst (EB), middle blastocyst (MB) and late blastocyst (LB) were 64.4, 81.0, and 20.0% respectively. For 3 min equilibrium, the survival rates of EB, MB, and LB were 69.9, 50.0 and 57.5% respectively. The survival rates of EB and MB were significantly higher than that of LB in 1.5 min equilibrium group (p<0.05), however, the significance was not observed in 3 min equilibrium groups. In cytoplasmic shrinkage before vitrification, the survival rates of EB, MB and LB were 92.9, 100 and 75.9% respectively. The survival rate of MB was significantly higher than that of LB (p<0.05). The survival rates of vitrified blastocysts by artificial dehydration and slow-frozen blastocysts were not significantly different as 88.9 and 66.7%, respectively. Conclusion: This study showed that the vitrification of human blastocysts using EM grid and artificial dehydration is an effective method. Therefore, these methods would be an useful techniques for blastocyst cryopreservation.

• 한국수정란이식학회지
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• 제4권1호
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• pp.1-13
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• 1989

This paper reviews the most important steps that have generated consistent progress in principles and developmental progress of embryo cryopreservation, and also study on freezing procedure and its application by conventional method and current improved method for freezing procedure and its appilcation of embryo cryopreservation in farm animals. Four were of particular interest: 1.The transport of water across the ccli membrane (zona pellucida) during freezing and thawing accordinglyplays a role in determing whether the celi survives. This movement of water is controlied mainly by extracellular phase changes and by the nature and concentration of any cryoprotective agent present. Therates of cooling, freezing and warming, and the intervals over which they are applied are further decisi've factors in determining whether a cryopreservation procedure allows survival after thawing. 2.The first successful deep freezing experiments with sheep morula and blastocysts during the seventies were based on the early procedures used for mouse embryos.Current research during the eighties is developed with the aim of simplifying and improving current procedures such as one-step dilution and rapid or ultra-rapid cooling by using the model of laboratory animals. 3.The conventional method for the embryo cryopreservation is described. An alternative to this method which may result in high survival and also in reducing of the freezing and thawing time is done by combing a permeable cryoprotectant such as glycerol, DMSO or propanediol and a non-permeable compound such as sucrose, trehalose, raffinose or lactose. 4.Finally a different approach to the preservation of embryos, named vitrification, is introduced. This procedure depends upon the ability of concentrated solutions of cryoprotective agents such as glycerol and propanediol to supercool to very low temperature (-196$^{\circ}C$) during rapid cooling before solidifying without formation of ice. However, more complete data are necessary for successful vitrification of blastocysts.

• 대한전자공학회논문지SP
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• 제41권3호
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• pp.175-182
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• 2004

화자인증이란 생체인식 방법 중의 하나로 사람의 목소리를 이용하여 사용자를 인증하는 방법이다. 현재까지 가장 많이 사용되는 화자인증 알고리즘으로는 HMM(Hidden Markov Model)과 DTW(Dynamic Time Warping)를 들 수 있는데, 이들 알고리즘은 사용자의 등록 및 인증을 위해 많은 수의 특징벡터를 필요로 하므로 스마트 카드와 같은 메모리가 제한된 시스템에는 적용하기 어려운 단점이 있다. 본 논문에서는 SVM(Support vector Machine)을 이용함으로써 적은 양의 메모리와 적은 계산량으로 화자인증을 수행할 수 있는 방법을 제안하였으며, 이의 실시간 처리를 위해 하드웨어 구조를 제시하였다. 한국어 4연숫자 데이터베이스를 이용하여 제안한 알고리즘의 성능을 평가한 결과, 기존 알고리즘에 비해 약간의 에러율 증가가 있었으나 수행시간 및 모델크기에서는 상당한 감소를 나타내었다. SVM을 이용한 화자인증 알고리즘을 하드웨어로 구현한 결과, 소프트웨어로 구현한 경우에 비해서 훈련시간은 175분의 1, 인증시간에서는 6분의 1의 감소를 나타내었다.

• 한국세라믹학회지
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• 제19권3호
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• pp.215-222
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• 1982

This study is to investigate the effect of a domestic pottery stone as a batch inclusion on the synthesis of porcelain bodies and their physical properties. The basic composition of porcelain bodies studied was consisted of 50wt% kaolin, 25wt% feldspar and 25wt% quartz. The inclusion of pottery stone was performed by partial substitution for either quartz or feldspar up to 25% of the total weight of batches. Sixteen porcelain bodied different in batch composition were prepared by firing them in the temperature range from 110$0^{\circ}C$ to 135$0^{\circ}C$ and their physical properties and microstructures were carefully examined. It was found that the inclusion of pottery stone could reudce the firing temperature for vitrification up to 5$0^{\circ}C$ but appreciably decreased the mechanical strength of sintered bodies. The most faborable result could obtain with partial substitution for both quartz and feldspar at same time up to 25% of the total batch weight.