• Magazine of the Korean Society of Agricultural Engineers
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• v.26 no.3
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• pp.46-58
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• 1984

This study was carried out to investigate the compressive strength and the other effects varying to seasons and curing days on the wet curing conditions of the plain concrete. The results obtained are summarized as follows; 1. The longer the wet curing days and the higher the temperature, the greater the compressive strength was expected. 2.。$_2$8, compressive strength of concrete at 28 days under the dry curing conditions showed a range in 64-76% of that under the wet curing conditions. 3. The seasonal variations in the compressive strength under the wet curing showed in order of summer>spring=autumn>winter, and that under the dry curing were in order of spring ≒autumn> summer> winter. 4. In order to obtain 90% of the design compressive strength, 7 days in spring or autumn and 2 weeks of the wet curing in summer were required. 5. The compressive strength of concrete under the wet curing by using wet straw bag cover was almost the same as that of water curing method. 6. Under the wet curing conditions, the higher the temperature, the greater the effect of the curing of concrete was obtained, however, the compressive strength of concrete was decreased under relatively higher (over 15$^{\circ}$ C) and lower temperature (below 4$^{\circ}$C). 7. Freezing damage was occured when temperature was below 0$^{\circ}$ C and humidity was relatively high. 8. A considerable differnce between estimation of $^{\circ}$$_2$8 from $^{\circ}$7 and measured one was appeared in case of the dry curing conditions. Oregon formula was appeared to be acceptable under the wet curing conditions. 9. In relationship between $^{\circ}$$_2$8 and $^{\circ}$7~, $^{\circ}$28=1. 52 $^{\circ}$7 under the wet curing conditions except winter season, and $^{\circ}$$_2$8 =(1.39-1, 48)$^{\circ}$7 under the dry curing conditions were shown.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.6
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• pp.183-194
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• 2013

Liquid urea based SCR has been used in the market to reduce NOx in the exhaust emission of the diesel engine vehicle. This system has several problems at low temperature, which are freezing below $-12^{\circ}C$, solid deposit formation in the exhaust, and difficulties in dosing system at exhaust temperature below $200^{\circ}C$. Also, it is required complicated exhaust packaging equipment and mixer due to supply uniform ammonia concentration. In order to solve these issues, solid urea, ammonium carbonate, and ammonium carbamate are selected as ammonia sources for the application of solid SCR. In this paper, basic research on reaction rate of three ammonia-transporting materials was performed. TGA (Thermogravimetric Analysis) and DTA (Differential Thermal Analysis) tests for these materials are carried out for various heating conditions. From the results, chemical kinetic parameters such as activation energy and frequency factor are obtained from the Arrhenius plot. Additionally, from test results of DSC (Differential Scanning Calorimeter) for these materials, chemical kinetic parameters using the Kissinger method are calculated. Activation energies of solid SCR from this experiment are compared with proper data of literature study, then obtained data of this experiment are used for the design of reactor and dosing system for candidate vehicle.

• Korean Journal of Food Science and Technology
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• v.20 no.5
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• pp.683-690
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• 1988

This study was conducted to determine the organoleptic and physical properties and carotenoid of commercial canned, frozen and freshly-made carrot juice. Samples were evaluated by sensory panel and measured for viscosity and acidity. For carotene analysis, HPLC of alpha- and beta-carotene, and spectrophotometry of total carotenoid content were used. Sensory evaluation indicated that the canned sample was less acceptable, especially for flavor and texture, than other juices, while forzen juice was considered as acceptable as freshly-made carrot juice. The canned product showed about 10 times higher viscosity and lower acidity than others. Between two kinds of frozen samples, one sample was the same as freshly-made sample for all parameters while the other showed less alpha-carotene content which was 2 times higher than that of canned one. Canned sample contained 70-77% of freshly-made or frozen samples in total carotenoid and beta-carotene content and 24% of freshly-made one in alpha-carotene. These results suggest that freezing process is a good preservation method for carrot juice with respect to sensory evaluation, physical property and carotenoid content.

• Analytical Science and Technology
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• v.33 no.4
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• pp.177-185
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• 2020

Human milk (HM) glycoproteins play important roles protecting infants against various pathogens. Recently, freezing HM is reported to affect some glycoproteins and freeze-drying is suggested as an alternative method. However, the effects of freeze-drying on HM glycoproteins were not evaluated yet. Six fresh HM samples were collected from three healthy mothers at 15 and 60th days of lactation from each mother. Each sample was divided into frozen and freeze-dried subgroups yielding totally 12 samples, and the glycoproteomic analysis was performed by liquid chromatography mass spectrometry. The results were compared between samples of 15 and 60th days of lactation, and before and after the freeze-drying. Totally, 203 glycoproteins were detected. The glycoprotein levels were not different between two groups of 15/60th day of lactation and before/after freeze-drying groups (P > 0.050). In addition, significant correlation of glycoprotein levels was found between the different lactation stages (r = 0.897, P < 0.001) and the status of freeze-drying (r = 0.887, P < 0.001) in a partial correlation analysis. As no significant change of HM glycoproteins was not found after the freeze-drying, we hope that introducing freeze-drying to HM banks is supported by the present study. This work was supported by the National Research Foundation (NRF) of Korea grant funded by the Korea government (MSIP) (No.2017R1D1A1B03034270; No.2020R1A2C1005082).

• Journal of the Korean Society of Propulsion Engineers
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• v.3 no.4
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• pp.1-11
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• 1999

Thermal behavior of spacecraft propulsion system utilizing monopropellant hydrazine ($N_2$$H_4$) is addressed in this paper. Thermal control performance to prevent propellant freezing in spacecraft-operational orbit was test-verified under simulated on-orbit environment. The on-orbit environment was thermally achieved in space-simulation chamber and by the absorbed-heat flux method that implements an artificial heating through to the spacecraft bus panels enclosing the propulsion system. Test results obtained in terms of temperature history of propulsion components are presented and reduced into duty cycles of the avionics heaters which are dedicated to thermal control of those components. The duty cycles are subsequently converted into the electrical power required in the operational orbit. Additionally, cyclic temperature of each component, which was made under thermal-balanced condition of spacecraft, is compared to the acceptable design range and justified from the viewpoint of system verification.

• Asian-Australasian Journal of Animal Sciences
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• v.18 no.9
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• pp.1242-1248
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• 2005

This study was designed to investigate the in vitro developmental ability and apoptosis of bovine embryos nucleartransferred (NT) with frozen-thawed or cooled donor cells. Cultured adult bovine ear cells were used as donor cells after sub-culturing to confluence (CC), cooling to 4$^{\circ}C$ for 48 h, or freezing-thawing (FT). Apoptotic cells in blastocysts were evaluated for apoptosis by terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) method. Fusion, cleavage and blastocyst rates were 69.0 (167/242), 68.8 (115/167), and 29.9 (50/167) with CC cells, 70.4 (88/125), 69.3 (61/88), and 29.6 (26/88) with cooled cells and 66.1 (117/177), 70.1 (82/117), and 13.7 (16/117) with FT cells, respectively. Blastocyst rates of NT embryos derived from FT cells were significantly lower than those from CC or cooled cells (p<0.05). In addition, NT blastocysts produced by using FT cells showed significantly higher apoptosis rates (6.4${\pm}$4.0%) than those produced by CC (2.8${\pm}$1.7%) or cooled (2.3${\pm}$1.3%) cells. However, cooling of donor cells had no significant adverse effect on blastocyst rate as well as apoptosis rate. Therefore, our results suggest that cooled cells may be used as an alternative to freshly cultured confluent culture cells, as donor cells, for the production of Somatic nuclear cloned cattle.

• Journal of Pharmacopuncture
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• v.12 no.3
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• pp.61-72
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• 2009

Objectives : This experimental study was performed to investigate the safety and efficacy of Bovis Calculus pharmacopuncture solution manufactured with freezing dryness method to use eye drop. To identify the use of it as eye drop, the eye irritation test of rabbits and the antibacterial test of Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, Aspergillus niger, Fusarium oxysporum, and Candida albicans were performed. Methods : 1. The eye irritation test of this material was performed according to the Regulation of Korea Food & Drug Administration(2005. 10. 21, KFDA 2005-60). After Bovis Calculus pharmacopuncture solution was administered in the left eye of the rabbits, eye irritation of the cornea, iris and conjunctiva was observed at 1, 2, 3, 4 & 7day. 2. After administering Bovis Calculus pharmacopuncture solution on bacterial species(Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, Aspergillus niger, Fusarium oxysporum, Candida albicans) which cause Keratitis, MIC(Minimum Inhibition Concentration) and the size of inhibition zone were measured. Anti-bacterial potency was also measured using the size of inhibition zone. Results : 1. After Bovis Calculus pharmacopuncture solution was administered in the left eye of the rabbits, it was found that none of nine rabbits have abnormal signs and weight changes. 2. After Bovis Calculus pharmacopuncture solution was medicated in the left eye of the rabbits, no eye irritation of the cornea, iris and conjunctiva was observed at 1, 2, 3, 4 & 7day. 3. There was no response to MIC on bacterial species(Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, Aspergillus niger, Fusarium oxysporum, Candida albicans) after Bovis Calculus pharmacopuncture solution was medicated. Conclusions : The present study suggests that Bovis Calculus pharmacopuncture solution is a nontoxic and non-irritant medicine, which does not cause eye irritation in rabbits, but dosen't have antibacterial effects on bacterial species(Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, Aspergillus niger, Fusarium oxysporum, Candida albicans) which cause Keratitis. These study result recommends that more research on other herbal medicines of eye drop for Keratitis are required.

• Korean Journal of Veterinary Research
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• v.38 no.2
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• pp.394-400
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• 1998

Cryopreservation of embryos by vitrification is a simple method to preserve bovine embryos for subsequent embryo transfer, but embryonic viability after vitrification has been inconsistent and low compared with conventional slow freezing. The aim of the present study is to examine the effect of serum or serum albumin in a vitrification solution and epidermal growth factor(EGF) or fibroblast growth factor(FGF) on in vitro viability of bovine blastocysts frozen by vitrification. Bovine blastocysts were produced by in vitro maturation, fertilization of follicular oocytes and culture of embryos in a synthetic oviduct fluid medium(SOFM) containing BSA and 19 essential and nonessential amino acids. Blastocysts with excellent or good morphology were selected at 7 or 8 days after culture and utilized for vitrification. In experiment 1, blastocysts were vitrified in a solution containing semi-fetal calf serum(SFCS) or BSA(5 or 10mg/ml) and then their subsequent viabilities were examined by culturing thawed embryos in a SOFM containing BSA and 19 amino acids. Effect of EGF or FGF added to a SOFM containing polyvinyl alcohol(PVA) on the viability of vitrified-thawed blastocysts was investigated in experiment 2. BSA added at 5 or 10mg/ml to a vitrification solution showed significantly higher(p < 0.05) developmental rate to expanded and hatching blastocysts than SFCS, but there was no significant difference in the developmental rate to hatched blastocysts after thawing. Supplementation of a culture medium with EGF and/or FGF significantly increased(p < 0.05) embryo development to expanded blastocysts compared with control but showed no beneficial effect on the development to hatching or hatched blastocysts. Coculture of thawed embryos with granulosa cells in a TCM 199 containing 10% fetal calf serum(FCS) showed the highest developmental rate to expanded, hatching and hatched blastocysts among the groups tested. In conclusion, supplementation of a vitrification solution with BSA at 5mg/ml and culture of thawed blastocysts in a medium containing EGF and/or FGF can improve in vitro viability of bovine blastocysts frozen by vitrification.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.533-536
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• 2008

This study is the application of phosphate magnesia cement for solidification of soils. The object of the study is the application of the pavment of the farm roads. The new pavement method must be environmental, ecologic and durable. So, for solidification of farm road's soil, we use magnesia cement as quick setting, high strength materials. At magnesia phosphate cement, mixing ratio of mono ammonium phosphate and magnesia is 4:6 and w/b is 50 wt%, it show 14 MPa of compressive strength, and high hydration heat. Solidified soils that mixing ratios of magnesia cement and soil are 4:6 and 5:5 have very high durability for freezing and thawing.

• Biotechnology and Bioprocess Engineering:BBE
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• v.9 no.5
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• pp.393-399
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• 2004

Useful genes can be Screened from various environments by construction of metagenomic DNA libraries. In this study, water samples were collected from several lakes in mid Korea, and analyzed by T-RFLP to examine diversities of the microbial communities. The crude DNAs r were extracted by the SDS-based freezing-thawing method, and then further purified using an $UltraClean^{TM}$ kit (MoBio, USA). The metagenomic libraries were constructed with the DNAs partially digested with EcoR I, BamH I, and Sac II in Escherichia coli DH 10B using the pBACe3.6 vector. About 44.0 Mb of metagenomic libraries were obtained with average inserts 13-15 kb in size. The bphC genes responsible for degradation of aromatic hydrocarbons via mets-cleavage were identified from the metagenomic libraries by colony hybridization using the bphC specific sequence as a probe. The 2,3-dihydroxybiphenyl (2, 3-DHBP) dioxygenase gene (bphC ), capable of degradation of 2,3-DHBP, was cloned and its nucleotide Sequences analyzed. The genes consisted of 966 and 897 base pairs with an ATG initiation codon and a TGA termination codon. The activity of the 2,3-DHBP dioxygenase was highly expressed to 2,3-DHBP and Showed a broad substrate range to 2,3-DHBP, catechol, 3-methylcatechol and 4-methylcatechol. These results in-dicated that the bphC gene identified from the metagenomes derived from lake water might be useful in the development of a potent strain for degradation of aromatic pollutants.