• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집E
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• pp.100-106
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• 2001

The size distributions of electrospray droplets from the Taylor cone in cone-jet mode are directly measured by using a freezing method and a transmission electron microscope (TEM) image processing technique. These results are compared with the data obtained by an aerodynamic size spectrometer (TSI Aerosizer DSP). The use of glycerol seeded with NaI and a freezing method make it possible to sample droplets with their original sizes preserved. Since pictures of droplets are taken with TEM with very low vapor pressure of the solution, evaporation is suppressed by freezing. For liquid flow rates below 1 nl/sec, the measured droplet diameters by the TEM image processing technique and the aerosizer are in the range of 0.25 to $0.32{\mu}m$ and 0.30 to $0.40{\mu}m$, respectively. Comparing the TEM data with the aerosizer measurements, it has been revealed that the TEM image processing technique can afford more accurate values of droplet size distributions in the submicron range of 0.1 to $0.4{\mu}m$.

• 대한공간정보학회지
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• 제13권4호
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• pp.19-25
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• 2005

본 연구의 목적은 GIS를 이용하여 도로의 노선계획시 예상되는 노면결빙구간을 추출함으로써 도로 안정성 확보에 대한 방안을 제시하는데 있다. 산악지역 도로계획의 경우 겨울철에는 결빙구간이 발생될 우려가 있다. 또한 도로의 신설 및 확장공사 턴키심의시 노면결빙율 평가자료가 요구되고 있다. 따라서 도로의 노선 계획시 기본설계에서부터 도로 각 구간에서의 일조 환경 및 노면결빙우려구간을 정량적으로 예측할 수 있는 분석방법이 필요하다. 본 연구에서는 동해고속도로 중 약 29km 구간에 대하여 3차원 모델링, 일조 시뮬레이션, 지오데이터베이스 구축, GIS 중첩 기능에 의한 공간분석을 통해 노면결빙 예상구간을 추출할 수 있었다. 본 연구를 통하여 음영에 따른 노면결빙이 우려되는 구간을 예측하고, 노면결빙위험 구간을 효과적으로 파악함으로써 최종적으로 정책결정자가 판단을 내리고 기본 설계시 반영하는 사전 안정성 평가 방안으로 사용할 수 있을 것이다.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2005년도 학술발표논문집
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• pp.381-386
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• 2005

In order to have compressive strength tests and frost heaving tests, two sorts of soil samples at Chonbuk-Do area were used. According to this research, the compressive strength of soil which was mixed by quick lime, was largely increased until 28 days but after 28 days, the increment of strength was seldom found and its maximum compressive strength increasing rate for content of quick lime was $10{\sim}15%$ scope. In the mixed rates of quick lime and briquette ash, the compressive strength of soil which was mixed by quick lime and briquette ash, was increased by increasing mixed rates of quick lime and its compressive strength was increased by additional quantity. The compressive strength of mixed soil within freezing-thawing 1 cycle was diminished around 30% compared to non-freezing soil's 28 days compressive strength but there were no movements after 2 cycle.

• 대한수의학회지
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• 제30권2호
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• pp.231-241
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• 1990

The present study was carried out to investigate the viability of frozen-thawed aggregated mouse embryos and to produce the chimeras. Different phenotypic embryos were obtained by mating ICR female mice with ICR or CBA male mice. The aggregated morulae were produced following aggregation of embryos at 4-, 8- and 12- to 16-cell stage. The desirable stage for the aggregation of the mouse embryos was 8- to 16-cell stage. The post-thawed in vitro survival rates of aggregated embryos in glycerol, DMSO and ethylene glycerol were 51.5, 78.6 and 69.4%, respectively. Although the higher survival was obtained in DMSO, there were no significant differences in the survival rates among the three cryoprotectants. A total of 155 frozen-thawed aggregated embryos were transferred to 11 recipient mice, 3 out of 7 offsprings were born to overt chimera. These experiments have proven that mouse chimeras can be obtained from frozen-thawed aggregated embryos.

• 한국가축번식학회지
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• 제11권3호
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• pp.155-160
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• 1987

This study was carried out to determine the effects of cryoprotectants, freezing and thawing rates on the survival of 8-cell mouse embryos. The female ICR mice were induced to superovulated by intraperitoneal injections of 5 i.u. PMSG and 5 i.u. HCG given 48h apart and then were paired with males of the same strain. They were killed and embryos were flushed from the oviducts and uteri on 3 days after injection of HCG. Embryos were flushed with modified Dulbecco's phosphate buffered saline and equilibrated with 1.5M-dimethyl sulfoxide (DMSO) or 1.5M-glycerol by 3-step procedure. The freezing rates of the embryos were 1$^{\circ}C$/min from room temperature to -5$^{\circ}C$ and the embryos were seeded at -5$^{\circ}C$. After being held for 3 min at the seeding temperature, the rates were 0.3$^{\circ}C$/min from -5$^{\circ}C$ to -35$^{\circ}C$. From -35$^{\circ}C$ to -7$0^{\circ}C$, the rates were divided into 0.1$^{\circ}C$/min, 1$^{\circ}C$/min and 1$0^{\circ}C$/min, respectively. After being held for 5 min at -7$0^{\circ}C$, the embryos were plunged directly into liquid nitrogen. The embryos were thawed at 4$^{\circ}C$/min and 12$^{\circ}C$/min from -196$^{\circ}C$ to 37$^{\circ}C$, and for 2 min in 37$^{\circ}C$ water bath, respectively. The average number of ovulation points and embryos recovered were 42.7 and 34 appearing 79.5% recovery rate. Eight cell embryos in the embryos recovered were 26.3. The survival rates of embryos according to the freezing rates in the presence of 1.5M-DMSO were 73.5~80.6% at 0.1$^{\circ}C$/min, 75.0~79.5% at 1$^{\circ}C$/min and 52.8~54.7% at 1$0^{\circ}C$/min, but in the presence of 1.5M-glycerol were 62.9~67.6% at 0.1$^{\circ}C$/min, 61.4~68.3% at 1$^{\circ}C$/min and 25.5~30.2% at 1$0^{\circ}C$/min. The survival rates of embryos were not affected by the thawing rates.

• 한국가축번식학회지
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• 제19권1호
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• pp.43-48
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• 1995

The purpose of this study was to examine the suvival rates of cryopreserved porcine embryos collected on Day 6 (Day 0=onset of estrus) with various cryprotectants. Eighty two embryos at different stages, ranged from expanded blastocyst to hatched blastocyst, were allocated to 6 experimental groups in different combinations of cryoprotectants glycerol, egg yolk and/or trehalose. Porcine embryos were cryopreserved using conventinal slow freezing precedures. The embryos were equilibrated with one of the freezing solutions, cooled from 25 to -7$^{\circ}C$ at 1$^{\circ}C$/min, seeded at -7$^{\circ}C$ frozen to -36$^{\circ}C$ at 0.5$^{\circ}C$/min, and then plunged into liquid nitrogen. The frozen embryos were thawed by immersion in 37$^{\circ}C$ water and the cryoprotectants were removed by dilution with 0.5M sucrose solution. Embryonic survival was estimated from the normal development of embryos for 12, 24 and 48hrs culture. Then the embryos were stained and their cell nuclei was counted. The survival rates of morphological embryos were significantly higher in group I (10% glycerol) or group IV (10% glycerol＋10% egg yolk＋0.5M trehalose) than those in other groups, although the nuclei number was quite higher in embryos treated with 10% glycerol and 0.25M trehalose at expended blastocyst. However, hatched blastocysts showed higher viability and nuclei number treated with either egg york or trehalose, but the survival rates after 48hrs of culture were quite low. These results indicate that egg yolk and trehalos as a supplement to freezing solutions can be useful to the cryopreservation ofn porcine embryos.

• Reproductive and Developmental Biology
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• 제28권3호
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• pp.155-159
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• 2004

This study was carried out to investigate the general characteristics and viability of sperm after freezing and thawing and the pregnancy rates after artificial insemination with thawed semen. The rates of viable sperm after slow and rapid freezing were 87.4±3.85% and 70.8±4.45%, respectively which were significantly lower than that of fresh semen control (91.7±3.45%). The mean concentration of epididymal sperm after dilution in 1.0 ml saline and. 3.0 ml extender in a various concentrations of cryoprotectants was 124.5±48.3 x 10/sup 6/ (range of 45 x 10/sup 6/ to 280 X 10/sup 6/ /ml). There was a significant difference not in the percentage of acrosome-reacted sperm, but in the percentage of capacitated sperm, between fresh and frozen-thawed epididymal semen. When frozen-thawed after diluting with tris-buffer extender containing glycerol, DMSO and ethylene glycol with concentration of 2 to 6%, the rates of epididymal sperm exposed to different cryoprotectants ranged from 14.4±4.7% to 20.7±5.8%, 17.8±5.2% to 36.5±4.9%, and 14.4±4.6% to 18.5±5.3%, respectively which were lower compare to fresh semen control. The pregnancy rate after artificial insemination with frozen semen was 70.6%, whereas that with fresh semen was 90.0% in dogs with naturally induced estrus.

• Reproductive and Developmental Biology
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• 제34권3호
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• pp.253-256
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• 2010

This study was performed to investigate the characteristics within ages and freezing tolerance of spermatozoa in Jindo Dog. Experimental animals were selected 12 herds within 1~8 year's old and collected semen for 2 times in a week. Collected semen was evaluated whole volume and sperm number with CASA system (SIAS, Medical Supply, Korea). Then seminal plasma were separated and diluted with modified Tris-egg yolk extender and added 4, 6 and 8% glycerol for 4 times to final concentration and equilibrated for 1.5 hrs. Before and after freezing, equilibrated semen were evaluated the survival rates. Total volume of sperm at 1~2 year old group is as $5.2{\times}10^8\;cells/ml$ largest and there were no significance among groups. The motility of 1~2 year old group is highest as 90.9% and there were significance among groups. Abnormal sperm showed similar among groups. The survival rate in terms of pre-freezing and post-freezing were decreased all levels of glycerol and reveled 87.0% to 64.5% in 4%, 87.5% to 51.9% in 6% and 73.4% to 29.7% in 8%, there were significant difference among the groups (p<0.05). These results suggest that the optimal sperm-freezing methods in Jindo Dog are utilized with modified Tris egg-yolk extender with 4% glycerol and were improve the reproductive activity by these methods.

• 한국수정란이식학회지
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• 제9권1호
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• pp.65-71
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• 1994

This study were carried out to investigate the effective concentration of cryoprotectant agents and sucrose by one-step straw method, and to determine the optimum thawing temperature and equilibration time of frozen bovine embryos. The bovine embryos following dehydration by cryoprotective agents and a various concentration of sucrose were directly plunged into liquid nitrogen and thawed in 3O$^{\circ}C$ water. Survival rate was defined by FDA test. The results are summarized as follows : 1. The survival rate of bovine embryos thawed after rapid freezing in the freezing medium containing a various kinds of cryoprotective agents added 0.25M and O.50M sucrose were 28.6% and 25.0%, 35.1% and 31.6%, 32.4% and 24.4%, 34.2% and 28.2%, 18.9% and 17.6%, 14.7.% and 21.6%, respectively. 2. The survival rate of bovine embryos thawed after rapid freezing in the freezing medium containing a various concentration of sucrose added 1.5M and 2.OM glycerol, i.5M and 2.OM DMSO and 1.5M and 2.OM propanediol were 22.9~37.8%, 2O.7~31. 3%, 19.2~30.0% and 17.2~25.0%, respectively. 3. The temperature thawed at 2$0^{\circ}C$ after rapid freezing of bovine embryos resulted in a significantly higher embryos survival rate than did at 3$0^{\circ}C$ and 35$^{\circ}C$. 4. The equilibration time on the survival rate of bovine embryos was attained after short period of time(2.5~5 min.) in the freezing medium higher than long period of time (1O~20 min.).

• 한국양식학회지
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• 제17권1호
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• pp.8-11
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• 2004

Milt of the catfish was stripped into immobilizing solution containing 175 mM NaCl and 30 mM Tris at pH 7.8 and was successfully cryopreserved after a stepwise freezing procedure. After stepwise thawing, motility of spermatozoa was slightly lower than that of fresh sperm. Batches of 40-80 eggs were fertilized with cryopreserved spermatozoa, after thawing and activation in solution containing 50 mM NaCl, 20 mM Tris and HCl at pH 7.8; this resulted in 62.2% fertilization success, compared to 70.6 % with fresh sperm.