• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.9
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• pp.442-445
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• 2006

In order to realize the commercial application of HTSC materials, it is necessary to develop the fabrication process of high Tc oxide superconductor materials with desired shape and for practical application and high critical current density as well as good mechanical strength which can withstand high lorenz force generated at high magnetic field. Much studies have been concentrated to develop the fabrication technique for high critical current density but still there are a lot of gap which should be overcome for large scale application of HTSC materials at liquid nitrogen temperature. Recently some new fabrication techniques have been developed for YBaCuO bulk superconductor with high mechanical strength and critical current density. In this project, the establishment of fabrication condition and additive effects of second elements were examined so as to improve the related properties to the practical use of YBaCuO superconductor, and we reported the production of the YBaCuO high Tc superconductor by the pyrolysis method.

• Journal of Plant Biotechnology
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• v.6 no.2
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• pp.119-124
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• 2004

For long-term conservation of germ plasm, somatic embryos of sweet potato are important because shoot tips are not amenable to liquid nitrogen storage. Somatic embryos from different genotypes were used for induction of somatic embryogenesis in a large number of genotypes. Somatic embryogenesis was induced on 2,4-D medium in all the 11 genotypes, collected from geographically distinct locations. Genetic fidelity of the regenerated plants was confirmed by morphological and RAPD markers.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.7
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• pp.981-986
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• 2009

The application of a cryogenic storage system is growing fast in different kinds of fields including to keep umbilical cord blood. Umbilical cord blood stem plays an important role in the treatment of a blood and immune system related genetic diseases, cancers and blood disorders. This study gives the optimal cryogenic system for cord blood banking. Three-dimensional models are employed and finite element method is used to do structure analyses of all designed models. The results shows model 3 have a good structure properties, and model 4 shows the best structure property as its maximum is 92.9 MPa. The other is too dangerous or infeasible to support load condition that allowed by STS 304. The results can be used in the design of these kinds of systems to obtain good predictions of trends over a wide range of design alternatives and operating conditions.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.343.2-343
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• 2002

Squeeze film dampers(SFDs) are designed and analyzed for radial superconducting bearings. The designed SFDs are mounted on the superconductors submerged in liquid nitrogen such that the dampers should supply additional damping to the relatively underdamped superconducting bearing support. Basic theory of SFD with superconducting bearing are introduced. Rotordynamic simulations are provided to support the feasibility of the superconducting magnetic bearings mounted on SFDs for a horizontal flywheel energy storage system.

• Clinical and Experimental Reproductive Medicine
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• v.51 no.1
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• pp.42-47
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• 2024

Objective: This study evaluated the effects of temperature and storage time on the quality and DNA integrity of freeze-dried sperm from individuals with normozoospermia. Methods: Normal sperm samples from 15 men aged 24 to 40 years were studied. Each sample was divided into six groups: fresh, freezing (frozen in liquid nitrogen), freeze-dried then preserved at room temperature for 1 month (FD-1m-RT), freeze-dried then preserved at room temperature for 2 months (FD-2m-RT), freeze-dried then preserved at 4 ℃ for 1 month (FD-1m-4 ℃), and freeze-dried then preserved at 4 ℃ for 2 months (FD-2m-4 ℃). The morphology, progressive motility, vitality, and DNA integrity of the sperm were evaluated in all groups. Results: In all freeze-dried groups, sperm cells were immotile after rehydration. The freeze-dried groups also showed significantly less sperm vitality than the fresh and frozen groups. Significantly more morphological sperm abnormalities were found in the freeze-dried groups, but freeze-drying did not lead to a significantly higher DNA fragmentation index (DFI). The DFI was significantly higher in the FD-2m-RT group than in the other freeze-dried groups. Conclusion: The freeze-drying method preserved the integrity of sperm DNA. The temperature and duration of storage were also identified as factors that influenced the DFI. Accordingly, more research is needed on ways to improve sperm quality in the freeze-drying process.

• Korean Journal of Poultry Science
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• v.45 no.1
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• pp.29-39
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• 2018

The goal of the present work was to determine the optimal addition amounts of liquid smoke and curing mixture to develop Chuncheon Dakgalbi with improved preference and shelf-life. In the first experiment, Chuncheon Dakgalbi was prepared with different amounts of liquid smoke. In the second experiment Chuncheon Dakgalbi was prepared with various amounts of curing mixture and 0.1% (w/w) liquid smoke. Different amounts of liquid smoke resulted in different aroma patterns, which were observed using an electronic nose, and Dakgalbi with 0.1% (w/w) liquid smoke had the highest score in overall acceptability. The addition of liquid smoke and curing mixture inhibited the growth of bacteria, slowed down the decline in pH, and delayed increased in volatile basic nitrogen contents and lipid oxidation. However, no clear effects were observed on instrumental color. From a consumer preference test, the highest preference score was achieved by added 0.2% (w/w) curing mixture. Liquid smoke and curing mixture extended shelf-life and improved preference of Chuncheon Dakgalbi. Considering the physicochemical, microbiological and consumer preference, it was recommended to add 0.1% (w/w) liquid smoke and 0.2% (w/w) curing mixture to Chuncheon Dakgalbi to enhance shelf-life and preference.

• Applied Chemistry for Engineering
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• v.18 no.2
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• pp.99-110
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• 2007

Efficient and inexpensive hydrogen storage is an essential prerequisite for the utilization of hydrogen, one of the new and clean energy sources for $21^{st}$ century. In this review, several storage techniques are briefly reviewed and compared. Especially, adsorption/storage via physisorption at low temperature, by using nanoporous adsorbents, is reviewed and evaluated for further developments. The adsorption over a porous material at low temperature is currently investigated deeply to fulfill the storage target. In this review, several characteristics needed for the high hydrogen adsorption capacity are introduced. It may be summarized that following characteristics are necessary for high storage capacity over porous materials: i) high surface area and micropore volume, ii) narrow pore size, iii) strong electrostatic field, and iv) coordinatively unsaturated sites, etc. Moreover, typical results demonstrating high storage capacity over nanoporous materials are summarized. Storage capacity up to 7.5 wt% at liquid nitrogen temperature and 80 atm is reported. Competitive adsorbents that are suitable for hydrogen storage may be developed via intensive and continuous studies on design, synthesis, manufacturing and modification of nanoporous materials.

• Journal of Animal Science and Technology
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• v.55 no.5
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• pp.427-434
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• 2013

This study was conducted to establish methods for preserving chicken primordial germ cells (PGCs) for long-term storage in liquid nitrogen and for developmental engineering or preservation of species. The purpose of this study is to clarify the effects of fetal bovine serum (FBS) or chicken serum (CS) treatment on the viability of cryopreserved PGCs from Korean Native Chicken (Ogye). PGCs separated from a germinal gonad of an early embryo at day 5.5-6 (stage 28) were suspended in a freezing medium containing freezing and protective agents (dimethyl sulfoxide (DMSO), ethylene glycol (EG) and glycerol). The values from 0, 5, 10, and 15 % DMSO plus FBS treatment were 21.6, 30.36, 36.42, 50.39, and 48.36 %, respectively. The viability of PGCs after freeze-thawing was significantly higher for 10% EG plus FBS treatment than for 10% EG + FCS treatment (p<0.05) (64.36% vs. 50.66%). This study establishes a method for preserving chicken PGC that enables systematic storage and labeling of cryopreserved PGC in liquid nitrogen at a germplasm repository and an ease of entry into a database. In the future, the importance for this new technology is that poultry lines can be conserved while work is being conducted to improve the production of germline chimeras.

• Korean Journal of Food Science and Technology
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• v.31 no.6
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• pp.1596-1603
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• 1999

Dongchimi (Korean-style fermented radish with juice) products were frozen to prevent further acidification and softening of texture by restraining microbial growth and enzyme activity during storage. Dongchimi juice and radish were separated prior to freezing process. Dongchimi radish was frozen at $-20^{\circ}C,\;-70^{\circ}C$ and immersed in liquid nitrogen and dongchimi juice was frozen at $-20^{\circ}C\;and\;-70^{\circ}C$. Frozen dongchimi samples were thawed with ambient temperatures of $4^{\circ}C\;and\;27^{\circ}C$ and with 915 MHz-microwave, respectively. Dongchimi radish immersed in liquid nitrogen and thawed with 915 MHz-microwave showed the highest pectinesterase activity and hardness, and the lowest polygalacturonase activity and color change, indicating that this quick freezing-quick thawing method can be used for the long-term storage of dongchimi products. Dongchimi juice frozen at $-70^{\circ}C$ and thawed with 915 MHz-microwave retained its pH and titrable acidity, and showed a largest reduction in total aerobic count and lactic acid bacteria.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.36 no.6
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• pp.545-553
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• 1991

To find out the basic data for the possibility of agricultural utilization for GSA (Glutamine Synthetase Activity), the effect of nitrogen on the GSA in wheat leaf discs, the variation of GSA after light treatment and the comparative activity of GS during preservation were studied. The result of this study suggested that GSA could play an important and direct regulatory role in the nitrogen assimilation by wheat. During the growth stage of wheat its integral activity was found to closely match the organic nitrogen content. GS may therefore be the rate limiting enzyme in inorganic N assimilation. Moreover, integral GSA was closely correlated with grain yield and grain nitrogen. GSA could be suitable to utilize as a parameter for super type selection and an indicator for optimum nitrogen fertilization. Throughout the experiment, the contents of NO; were increased by N fertilization so that the NO; content was not attributable to change in the level of GSA. At investigation during dark-light transition of culture, no change in the level of GSA was observed until after 8-14 hours in the light treatment. And the level of GSA in wheat leaf discs during preservation at refrigerated storage $(-20^{\circ}C)$ was stable until 12 weeks, when its leaf discs were sampled with liquid nitrogen.