• Journal of the Korean Society of Safety
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• v.14 no.1
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• pp.208-215
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• 1999

The creep behavior of a rapidly solidified and consolidated Al-9.45wt%Fe-4.45wt%Cr alloy were investigated in the stress range 40 to 115 MPa and temperature range 300(0.53Tm) to 441$^{\circ}C$(0.66Tm). It is of use to available aerospace and automobile industries for the improved performance of materials used at high temperature. Because Al alloys with improved creep resistance offer the potential for lower weight and reduced costs in aerospace and automobile components (e.g., structural members and engine parts) through the replacement of heavier and more costly materials, the safety in use at high temperature is good. The alloy is characterized by high stress exponents and activation energies for creep, which are greatly dependent on the stress and temperature. Because the creep stress is seen to cause a strongly significant enhancement of coarsening, the coarsening rate of the dispersed particles in all crept specimens is faster than that in isothermally annealed specimens. Dislocations connecting dispersoids are observed more cofrequently in crept specimens with higher stress and lower temperature. The creep strain rates in the power law creep regime were found to be predicted much better by the Shorty and Rosler/Arzt equation with the inclusion of a threshold stress and dislocation detachment mechanism. The dispersoids in this alloy were acting a source of void nucleation that finally leaded to ductile fracture within the grain so called intergranular. Each void was initiated, grown and failed at the dispersoids in the aluminium matrix. Grain boundary accommodation of the slip produced, which result in initiation of the void and then final transgranular fracture. Therefore, it was confirmed that these dispersoids played an important role in the fracture mechanism by the formation of $Al_{13}Fe_4$, $Al_{13}Cr_2$ and $Al_2O_3$.

• Korean Journal of Animal Reproduction
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• v.11 no.3
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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.

• Journal of Life Science
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• v.19 no.3
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• pp.378-383
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• 2009

Agrobacterium tumefaciens-mediated transformation procedure for the phalaenopsis orchid, established by using Protocorm-like bodies (PLBs), was aimed at the introduction of target genes into individuals with divergent genetic backgrounds. PLBs obtained from the axillary bud of a peduncle were maintained on a hyponex medium supplemented with 1 g/l of activated charcoal, 30 g/l of sucrose and 0.1 mg/l thiamine. The multiplication rate of PLBs was about 90% in case of subculture PLBs to be cut transversely into 1/3 part from top position. The PLBs were inoculated with Agrobacterium strain EHA105 harboring both $\beta$-glucuronidase (GUS) and hygromycin-resistant genes for 20 minutes after dipping treatment. Transformation efficiency was the highest with a Agrobacterium culture medium and dipping treatment of O.D. 0.8. Newly induced PLBs were put on selection medium containing 1 mg/l hygromycin for 2 months. Hygromycin-resistant phalaenopsis plants that regenerated after the selection culture of PLBs showed histochemical blue staining due to GUS. Transgene integration of the hygromycin-resistant plants was confirmed by PCR and Southern blot using GUS specific primers and probe.

• Journal of the Korean GEO-environmental Society
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• v.10 no.5
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• pp.19-26
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• 2009

Rammed Aggregate Pier (RAP) method is intermediate foundation between deep and shallow foundation, and it has been built in world wide. RAP represents a relatively new method that has grown steadily over 19 years since Geopier of USA developed this revolutionary method in 1989. The investigation and research in domestic is not accomplished. In this paper, the examined details of different spacing of piles, bearing capacities, respectively, conclude with recommendations on how RAP can be used in future needs. This documentation further provides comparisons of the laboratory test results which were obtained from changing the spacing of piles, namely installed rammed aggregate pier. Laboratory model test was administered in a sand box. Strain control test was conducted to determine the bearing capacities of the piers; 20 mm, 30 mm and 40 mm RAP in diameter using drilling equipment to make holes were installed in sand at initial relative densities of 40%. By comparing different spacing of piles, in this experiment, piles are spaced structually span, form a ring shape, narrowing the distance of each other, to the center. the result shows that as diameter of pier is bigger in diameter, bearing capacity also dramatically increased due to raised stiffness. Also, as the space between each piers was closed, the settlement rate of soil was decreased significantly. From the test results, as the space between each piles were getting closer, it allows greater chances to have more resistance to deformation, and shows more improved stability of structures. After from the verification work which is continuous leads the accumulation of the site measuring data which is various, and bearing capacity and the settlement is a plan where the research will be advanced for optimum installed RAP.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.8
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• pp.62-68
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• 2016

The feeder cable assembly is an automotive part used for telecommunication. If it malfunctions, the control and safety of the automobile can be put at risk. ALT (Accelerated Life Testing) is a testing process for products in which they are subjected to conditions (stress, strain, temperatures, etc.) in excess of their normal service parameters in an attempt to uncover faults and potential modes of failure in a short amount of time. Failure is caused by defects in the design, process, quality, or application of the part, and these defects are the underlying causes of failure or which initiate a process leading to failure. Thermal shock occurs when a thermal gradient causes different parts of an object to expand by different amounts. Thermal shock testing is performed to determine the ability of parts and components to withstand sudden changes in temperature. In this research, the main causes of failure of the feeder cable assembly were snapping, shorting and electro-pressure resistance failure. Using the Coffin-Manson model for ALT, the normal conditions were from Tmax = $80^{\circ}C$ to Tmin = $-40^{\circ}C$, the accelerated testing conditions were from Tmax = $120^{\circ}C$ to Tmin = $-60^{\circ}C$, the AF (Acceleration Factor) was 2.25 and the testing time was reduced from 1,000 cycles to 444 cycles. Using the Bxlife test, the number of samples was 5, the required life was B0.04%.10years, in the acceleration condition, 747 cycles were obtained. After the thermal shock test under different conditions, the feeder cable assembly was examined by a network analyzer and compared with the Weibull distribution modulus parameter. The results obtained showed good results in acceleration life test mode. For the same reliability rate, the testing time was decreased by a quarter using ALT.

• Journal of Aquaculture
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• v.11 no.4
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• pp.487-493
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• 1998

This study was conducted to investgate the effect of fish meal analogue (FMA) on the growth of Israeli carp, Cyprinus carpio averageing 43g. Leather meal, meat and bone meal, feather meal, squid liver powder, poultry by-product and blood meal were used for ingredient of FMA. Four experimantal diets were formulated to contain 36% crude protein and 15.4 kJ available enery g-1. The percentage of follows ; Diet 1, 100% 3, 60% WFM + 40% FMA (40% FMA) ; Diet 4, 40% WFM + 60% FMA (60% FMA). In this expriment, fingerling Israeli carp averaging 43 g were assigned to each diet treatment. When the experiment was terminated, weigth gain (WG), feed conversion (FC), specific growth rate (SGR) and protein efficiency ratio (PER) were measured respectively. In the experiment, WG, FC, SGR and PER of Diet 2 were not significantly different from those of the control diet (P0.05). And WG, FC and SGR of Diet 3 were not significantly of the control Diet. In Diet 4, WG, FC and PER were not significantly different from those of the control Diet, but SGR was lower than that fo the control Diet. According to the results from this study, it might be possible to replace fish meal protein by FMA up to 60% in fingerling Israeli carp diets.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.2
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• pp.211-216
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• 2003

This study was carried out to determine the antioxidative, antimutagenic, and anticancer effects of Rhodiola sachalinensis root using 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical donating method, Ames test and cytotoxicity, respectively. Rhodiola sachalinenis root were extracted with ethanol and then further fractionated to n-hexane, chloroform, ethyl acetate (EtOAc), butanol and water, stepwise. Among five fractions, the Etohc fractions showed the highest electron donating activities (14.3 $\mu$g/mL). The inhibition rate of ethanol extract (200$\mu$g/plate) of Rhodiola sachalinensis root in the S. typhimurium TA100 strain showed 89.1% inhibition against the mutagenesis induced by MNNG. In addition, the suppression of EtOAc fractions with same concentration of Rhodiola sachalinensis root in the S. typhimurium TA98 and TAI00 strains showed 89.7% and 91.5% inhibition against 4NQO, respectively. The suppressions under the same condition against B($\alpha$)P and Trp-P-1 in the TA98 and TA100 strains were 94.2% and 95.7%, and 92.3% and 93.8%, respectively. The cytotoxic effects of Rhodiola sachalinensis root against the cell lines with human lung carcinoma (A549), human hepatocellular carcinoma (HepG2), human gastric carcinoma (AGS) and human breast adenocarcinoma (MCF-7) were inhibited with the increase of the extract concentration. The treatment of 1.0 mg/mL Rhodiola sachalinensis root of EtOAc fraction showed strong cytotoxicities of 90.5%, 81.5%, 92.2% and 82.6% against A549, HepG2, AGS and MCF-7, respectively.

• Journal of the Microelectronics and Packaging Society
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• v.26 no.4
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• pp.63-68
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• 2019

Dielectric and piezoelectric properties of PIN-PMN-PT piezoelectric single crystals with variation of temperature and compressive stress were investigated. The crystal phase of the single crystal was changed from the ferroelectric rhombohedral structure to tetragonal structure in the 110℃ region and from the tetragonal structure to the paraelectric cubic structure in the 190℃ region. The piezoelectric constant and relative dielectric constant were calculated from the rate of change of polarization and displacement with the application of electric field, which was similar to the value measured from the instrument. As the compressive stress applied to the sample increased, the piezoelectric constant d₃₃ and relative dielectric constant values tended to increase. When the compressive stress applied to the sample at 5℃ was 60 MPa, the d₃₃ was calculated as 4,500 pC/N. At 60℃, the relative dielectric constant of 62000 was calculated when the compressive stress applied to the sample was 40 MPa. The increase in piezoelectric constant and relative dielectric constant when the compressive stress increased could be attributed to the phase transition from the rhombohedral structure to orthorhombic.

• The Korean Journal of Mycology
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• v.48 no.2
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• pp.75-85
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• 2020

The collection of biological data of indigenous species must comply with the Nagoya Protocol. Fungi contain various bioactive substances making them an attractive source of several products, including food and medicines. In this study, we investigated the growth characteristics of five indigenous fungal strains, Fomitiporia punctata, Polyporus ulleungus, P. brumalis, Gymnopus subnudus, and Tyromyces kmetii, isolated from samples collected in the Ulleungdo Island. The growth rates for each strain were assessed across various temperatures (20 ℃ to 35 ℃), culture media (Potato dextrose agar, Malt extract & Yeast extract agar, Malt extract agar, Malt extract & peptone agar, Sabouraud dextrose agar, and Modified Melin-Norkrans agar), and pH conditions (4.0 to 8.0). Additionally, we assessed the mycelial growth characteristics in liquid culture. The mycelial growth in different media varied across species; specifically, F. punctata (in MMNA), G subnudus (in MMNA), and P. brumalis (in MEPA) showed rapid growth. Optimal growth temperatures ranged between 25 ℃ and 30 ℃ for most species, with the exception of T. kmetii and P. brumalis, which were able to grow across all the temperatures tested. P. brumalis showed the best growth rate, whereas P. ulleungus showed the lowest growth potential. The optimal pH conditions for mycelial growth ranged between 4.0 and 5.0. In experiments using culture flasks, the dry weight of the culture filtrates decreased with the increasing incubation time and showed a significant decrease between 1 and 6 months of incubation, indicating that the five strains take longer than a month to fully use the culture media. Our findings highlight and establish the optimal growth conditions for five different fungal species that can be used in future application studies.

• Korean Journal of Microbiology
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• v.26 no.4
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• pp.283-290
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• 1988

A spontaneous revertant of mutation rbsB103 that is ribose taxis-positive was characterized. This revertant was found to be export-competent in the export of ribose-binding protein shown by the disappearance of accumulated mutant precursor protein and the export of mature ribose-binding protein to the periplasm. The reversional change was shown to be in the region of risB gene that codes for the amino terminal portion of ribose-binding protein. Analysis by high-performance liquid chromatography of peptide patterns of ribose-binding proteins confirmed the relationship between the wild-type and the revertant proteins as shown for the mutant previously (Iida et al., 1985). When the processing rate of presursor proteins from the wild type and the revertant strain in vivo was compared by pulse-chase experiment, it was found that processing is less efficient than normal in the revertant. Purified mature proteins from both wild-type and revertant were subjected to amino acid sequencing. The results confirmed the amino acid changes deduced from the DNA sequencing and showed that processing of the revertant precursor occured in the correct position even though there are two different amino acids present in the signal sequence.