• Journal of Embryo Transfer
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• v.9 no.2
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• pp.173-180
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• 1994

The present experirnents on cryopreservation were carried out to investigate effect of solution toxicity, equilibration time and cell stages on the post-thaw survival of mouse morulae and blastocyst embryos cryopreserved by vitrification in EFS solution. The mouse embryos were exposed to the EFS solution in one step at room temperature, kept in the EFS solution during different period for toxicity test, vitrified in liquid nitrogen and thawed rapidly. After the mouse morulae embryos were exposed to EFS solution for 2 and 5 ruin. at room temperature and then they were washed in 0.5 M sucrose solution and basal mediurn(D-PBS + 10% FCS), they were cultured to examined cryoprotectant toxicity induced injury during exposure, most of embryos developed to expanded blastocysts(100 and 90.0%). However, when the exposure time was extended to 10 and 20 min, these development rates dropped dramatically in 10 ruin. (75.0%) and 20 ruin. (4.5%), respectively. When the compacted morulae were vitrified in EFS solution after equilibration for 2 and 5 min, the embryos have developed to normal blastocyst following thawing, washing and culture processes was 89.3 and 89.6%. However, when the exposure time was expanded to 10 ruin, this survival rate dropped to 68.8%. When the blastocyst were vitrified in EFS solution after equilibration for 2, 5 and 10 minutes, the survival rate of embryos which developed to normal blastocyst following thawing and culture processing were 58.5, 46.7 and 22.4%, respectively. The optimal time of equilibration of mouse morula and blastocysts in EFS solution seemed o be 2 and 5 ruin.

• Development and Reproduction
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• v.3 no.1
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• pp.107-111
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• 1999

To find out the desirable cryoprotectant for cryopreservation of bivalve trochophores, four types of cryoprotectant were tested with trochophores of the pearl oyster (pinctada fucata martensii) generally used in the pearl production in Korea. Each cryoprotectant (dimethyl sulfoxide, ethylene glycol, glycerol and 1,2-propanediol) was mixed with 0.2 M sucrose to make final concentrations of 0.01, 0.1, 1.0 and 2.0 M. The trochophores were immersed in each preparation, waiting for 10 minutes to reach equilibration and cryopreserved in the liquid nitrogen (-l96$^{\circ}C$). Survival rate of trochophores thawed after cryopreservation increased as the media concentration increase. However, a few number of the trochophores seemed to be damaged with the efflux of cell inclusions. Our study rsults indicate that desirable cryoprotectants for cryopreservation of pearl oyster trochophores are 1.0~2.0 M dimethyl sulfoxide and ethylene glycol : 82.8~97.4% of the trochophores cryopreserved with these media survived after thawing.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.3
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• pp.83-89
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• 2011

Diesel engines can produce higher fuel efficiency and lower $CO_2$ emission, they are subject to ever more stringent emission regulation. However, there are two major emission concerns fo diesel engines like such as particulate matter (PM) and nitrogen oxides (NOx). Moreover, it is not easy to satisfy the regulations on the emission of NOx and PM, which are getting more strengthened. One of the solutions is to apply the new combustion concept using multistage injection such as HCCI and PCCI. The other solution is to apply after-treatment systems. For example, lean NOx trap catalyst, Urea-SCR and others have various advantages and disadvantages Especially, Urea-SCR system have advantages such as a high conversion efficiency and a wide operation conditions. Hence the key factor to implementation of Urea-SCR technology, good mixing of urea(Ammonia) and gas, reducing Ammonia slip. Urea mixer components are required to facilitate evaporation and mixing because the liquid state of urea poses significant barriers for evaporation, and the distance to mixer is the most critical that affect mixer performance. In this study, to find out the distance from injector to mixer and simulation factor, a laser diagnostics and high speed camera are used to analyze urea injector spray characteristics and to present a distribution of urea solution in transparent manifold In addition, Droplet Uniformity Index is calculated from the acquired images by using image processing method to clarify the distribution of spray.

• Korean Journal of Animal Reproduction
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• v.13 no.3
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• pp.134-140
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• 1989

Studies were conducted to seek reasonable methods of rapid freezing of mouse embryos using liquid nitrogen. The effects of the cryoprotectants concentration and the substitution of raffinose to sucrose in freezing and dilution medium on mouse embryo survival rates were determined using the FDA-test. The summarized results are as follows : 1. When 0.3M of sucrose was added into the freezing and dilution medium, FDA scores of embryos were 1.48(1.5M), 3.81(3.0M) and 4.10(4.5M). Higher FDA scores of embryos were obtained in 3.0M and 4.5M glycerol concentrations (P<0.05). 2. With the addition of 0.3M raffinose to the freezing and dilution medium, FDA scores of embryos did not significantly differ between glycerol levels ; 3.97(1.5M), 4.11(3.0M) and 3.54(4.5M). Higher scores of embryos existed in 3.0M glycerol concentration. 3. Concentration of sucrose or raffinose in freezing and dilution medium affected FDA scores of embryos. When sucrose concerations of 0.3, 0.5 and 1.0M were added to the freezing medium, FDA scores of embryos were 3.12, 2.38 and 0, respectively. However, when the same concentrations of raffinose were added to freezing medium, the FDA scores were 4.21, 2.91 and 0. In both cases, better FDA scores of embryos were attained in 0.3M of sucrose or raffinose (P<0.01).

• Applied Chemistry for Engineering
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• v.1 no.1
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• pp.23-29
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• 1990

The effect of a rapid freeze pretreatment of organic ion exchange resins on their grinding properties was studied. It was found that the structure of ion exchange resins was defected by freezing pressure formed in the process of rapid freezing. The defected resins didn't recover their own structure after thawing and those could be easy to be broken at room temperature by small force. Therefore, organic ion exchange resins could be ground readily at room temperature after rapid-freezing the fully swelled resins using by solid carbon dioxide, or liquid nitrogen. The rapid freeze pretreatment of cation exchange resins was very effective on grinding in particular. However, the effect of the pretreatment of anion exchange resins on grinding was less than that of cation exchange resins. In case of anion exchange resins, the ionic form of affected the grindability remarkably.

• Preventive Nutrition and Food Science
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• v.18 no.2
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• pp.145-149
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• 2013

We tested for residual pesticide levels in dried vegetables in Seoul, Korea. A total of 100 samples of 13 different types of agricultural products were analyzed by a gas chromatography-nitrogen phosphate detector (GC-NPD), an electron capture detector (GC-${\mu}ECD$), a mass spectrometry detector (GC-MSD), and a high performance liquid chromatography- ultraviolet detector (HPLC-UV). We used multi-analysis methods to analyze for 253 different pesticide types. Among the selected agricultural products, residual pesticides were detected in 11 samples, of which 2 samples (2.0%) exceeded the Korea Maximum Residue limits (MRLs). We detected pesticide residue in 6 of 9 analyzed dried pepper leaves and 1 sample exceeded the Korea MRLs. Data obtained were then used for estimating the potential health risks associated with the exposures to these pesticides. The estimated daily intakes (EDIs) range from 0.1% of the acceptable daily intake (ADI) for bifenthrin to 8.4% of the ADI for cadusafos. The most critical commodity is cadusafos in chwinamul, contributing 8.4% to the hazard index (HI). This results show that the detected pesticides could not be considered a serious public health problem. Nevertheless, an investigation into continuous monitoring is recommended.

• Culinary science and hospitality research
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• v.14 no.2
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• pp.286-292
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• 2008

The purpose of this study was to examine the effects of freezing and thawing methods on the quality of pork meat. The freezing methods for pork meat were the cryogenic freezing with liquid nitrogen gas, fast freezing at $-70^{\circ}C$ and normal freezing at $-20^{\circ}C$. The thawing methods were tested on low temperature thawing at refrigerative temperature($4^{\circ}C$), room temperature($20^{\circ}C$), high temperature($60^{\circ}C$) and using microwave. The quality of pork meat frozen by cryogenic methods was better than those of fast and normal freezing methods. The cooking hardness of pork meat frozen by cryogenic method showed the highest value as 1,898 g. In case of fast freezing, the hardness of pork meat was 1,472 g and that of normal frozen pork meat was 1,541 g. The high cooking hardness value of cryogenic frozen pork meat showed that the cryogenic freezing method made less freeze damage like textural softness. The drip-loss of pork meat thawed at refrigerative temperature($4^{\circ}C$), room temperature($20^{\circ}C$), high temperature($60^{\circ}C$) were shown lower than that of microwave thawing. The cooking hardness of pork meat that was thawed by microwave showed the lowest value among the thawing methods. The cryogenic freezing was the most useful freezing method for preserving quality, decreasing the freeze damage of pork meat. And thawing at refrigerative temperature was the most effective method to prevent quality loss and weight loss by drip-loss.

• The Korean Journal of Ceramics
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• v.4 no.4
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• pp.297-303
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• 1998

The effect of aliovalent dopants, $ Nb_2O_5$ and MnO, on the phase stability of 12 mol% ceria partially-stabilized zirconia (Ce-TZP) polycrystals was studied. Both dopants (MnO and $ Nb_2O_5$) significantly increased the stability of the tetragonal zirconia phase (Mb temperature lower than liquid nitrogen temperature). The enhancement of the stability of the tetragonal phase in Ce-TZP doped with 1 mol% of Mno(Ce-TZP/MnO) andCe-TZP doped with 1 mol% of $ Nb_2O_5$(Ce-TZP/$ Nb_2O_5$) were explained by the significant reduction of the driving force, -${\Delta}$Gchem, for the tetragonal-to-mono-clinic phase transformation caused by the addition of MnO and $ Nb_2O_5$. The enhanced stability of the tetragonal phase in the Ce-TZP and Al2O3 composite (Ce-TZP/$Al_2O_3$) is believed to be caused by smaller grain size, moderate reduction in the chemical driving force and increase in the strain energy barrier to the transformation. Mechanical properties of the Ce-TZP and the Ce-TZP/$Al_2O_3$ with (i) the same grain size and (ii) the same Mb temperature were examined by measuring stress-strain behavior in 3 point bending. The Ce-TZP/$Al_2O_3$ composite doped with 1.3w% MnO (Ce-TZP/$Al_2O_3$/MnO), which had the same grain size as the Ce-TZP and De-TZP/$Al_2O_3$ showed more transformation plasticity than either the Ce-TZP or the Ce-TZP/$Al_2O_3$ composite. The Ce-TZP wihch had the same Mb temperature as that of the Ce-TZP/$Al_2O_3$/MnO did not show any transformation plasticity.

• Korean journal of applied entomology
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• v.39 no.3
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• pp.149-152
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• 2000

Cryopreservation of infective juveniles of entomopathogenic nematode, Steinernema carpocapsae Weiser, was conducted at $-190^{\circ}C$ liquid nitrogen and its, efficacy was analysed on nematode survival and pathogenicity with glycerol pretreatments and storage periods. Infective juveniles were pre-treated before being frozen by incubating the nematodes in 22% glycerol for each of 6, 12, and 24 h, followed by 70% methanol at $0^{\circ}C$ for 10 minutes. Just after glycerol and methanol incubations, subsamp1es of the nematodes were resuspended in 0.85% saline and maintained during 24h for viability determination. Different glycerol incubation periods significantly affected the nematode susceptibility to methanol infiltration. Six hour incubation in glycerol resulted in much less nematode survival than did 12 h or 24 h incubation. About 70% of the infective juveniles frozen at $-190^{\circ}C$ for 5 months, preincubat-ed in glycerol at least for 12h, were able to survive after being resuspended in 30°C saline. They did not also show any change in their pathogenicity during cryopreservation. These results suggest an improved technique for long-term storage of the entomopathogenic nematodes.

• Journal of Veterinary Clinics
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• v.21 no.4
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• pp.363-368
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• 2004

To investigate the effects of seeding during freezing procedure on post-thaw viability, motility, and acrosome integrity of boar spermatozoa, semen from 5 Yorkshire boars were collected for this experiment. Raw semen were diluted with Merck I, subsequently added with cooling diluent containing lactose and egg yolk and with freezing diluent containing glycerol. The diluted semen were frozen on the rack in the styrofoam box filled with liquid nitrogen at the distance of 5 cm or I cm above LN2 level. Seeding was performed to only a group of straws frozen at 5 cm away on the surface of LN2. The frozen semen were thawed in $50^{\circ}C$C water and the viability and local motility were analyzed by sperm analysis imaging system. A part of thawed semen was taken for the examination of morphology of apical ridge of the acrosome to compare with the effect of seeding between the seeding-treated and non treated groups. I. Post-thaw viability was considerably higher in seeding-treated sperm than non-seeding group (p<0.01), however, no difference of local motility was obtained among the groups. 2. At three hours after thawing, viability was also higher in seeding-treated group than non-treated group (p<0.05), along with no difference of motility among the groups. 3. Higher normal acrosome integrity was obtained in the seeding-treated sperm than non-treated groups (p<0.01). 4. Between non-seeded groups, higher normal acrosome integrity was obtained in the sperm group frozen at 5cm upper on the surface of LN2 than that frozen at 1cm away (p<0.01). These results indicated that seeding treatment during freezing boar spermatozoa was beneficial to post-thaw viability and normal acrosome integrity.