• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.08a
• /
• pp.287.1-287.1
• /
• 2013

The Isolation of few-layered transition metal dichalcogenides has mainly been performed by mechanical and chemical exfoliation with very low yields. in particular, the two-dimensional layer of molybdenum disulfide (MoS2) has recently attracted much interest due to its direct-gap property and potential application in optoelectronics and energy harvesting. However, the synthetic approach to obtain high-quality and large-area MoS2 atomic thin layers is still rare. In this account, a controlled thermal reductionsulfurization method is used to synthesize large-MoOx thin films are first deposited on Si/SiO2 substrates, which are then sulfurized (under vacuum) at high temperatures. Samples with different thicknesses have been analyzed by Raman spectroscopy and TEM, and their photoluminescence properties have been evaluated. We demonstrated the presence of single-, bi-, and few-layered MoS2 on as-grown samples. It is well known that the electronic structure of these materials is very sensitive to the number of layer, ranging from indirect band gap semiconductor in the bulk phase to direct band gap semiconductor in monolayers. This synthetic approach is simple, scalable, and applicable to other transition metal dichalcogenides. Meanwhile, the obtained MoS2 films are transferable to arbitrary substrates, providing great opportunities to make layered composites by stacking various atomically thin layers.

• Korean Journal of Veterinary Research
• /
• v.33 no.4
• /
• pp.757-762
• /
• 1993

The ovaries of Korean Native cows or heifers were obtained from an abattoir and kept on 20 to $25^{\circ}C$ and transported to laboratory within 2 hrs. The follicular oocystes were collected from 2~6mm follicles in diameter and classified into 3 grades by the morphology of cumulus cells attached. The oocytes were matured in vitro(IVM) for 24 hrs. in TCM-199 supplemented with $23{\mu}g/ml$ FSH, $10{\mu}g/ml$ LH, $1{\mu}g/ml$ estradio-17 ${\beta}$ and granulosa cells at $39^{\circ}C$ under 5% $CO_2$ in air. They were fertilized in vitro(IVF) by incubation for 12 hrs. of epididymal spermatozoa pretreated with heparin, and then the zygotes were co-cultured in vitro(IVC) with oviductal epithelial cells for 7 to 9 days. Assessment of maturation revealed that 93.0%(147/158) of grade I oocytes had expanded of cumulus cells, which was higher(p<0.05) than the 79.4%(85/107) of grade II oocytes. Compared to epididymal sperm(32.9%), the insemination with frozen and thawed sperm resulted in slightly lower(20.5%), but not significant, development to morulae and blastocysts from grade I oocytes. Co-culture of bovine IVF embryos with oviductal epithelial cells improved the development to transferable embryos significantly(38.1%), compared to co-culture with granulosa cells(20.0%). When VF bovine embryos were vitrified at blastocyst, the post-thaw survival rate was obtained higher resulf for 1 min. equilibration time(82.6%) or 2 min.(73.9%) than 3 min.(18.2%) in EFS solution.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2011.05a
• /
• pp.16-16
• /
• 2011

Statistics of extreme rainfall play a vital role in engineering practice from the perspective of mitigation and protection of infrastructure and human life from flooding. While flood frequency assessments, based on river flood flow data are preferred, the analysis of rainfall data is often more convenient due to the finer spatial nature of rainfall recording networks, often with longer records, and potentially more easily transferable from site to site. The rainfall frequency analysis as a design tool has developed over the years in New Zealand from Seelye's daily rainfall frequency maps in 1947 to Thompson's web based tool in 2010. This paper will present a history of the development of New Zealand rainfall frequency analysis methods, and the details of the latest method, so that comparisons may in future be made with the development of Korean methods. One of the main findings in the development of methods was new knowledge on the distribution of New Zealand rainfall extremes. The High Intensity Rainfall Design System (HIRDS.V3) method (Thompson, 2011) is based upon a regional rainfall frequency analysis with the following assumptions: $\bullet$ An "index flood" rainfall regional frequency method, using the median annual maximum rainfall as the indexing variable. $\bullet$ A regional dimensionless growth curve based on the Generalised Extreme Value (GEV), and using goodness of fit test for the GEV, Gumbel (EV1), and Generalised Logistic (GLO) distributions. $\bullet$ Mapping of median annual maximum rainfall and parameters of the regional growth curves, using thin-plate smoothing splines, a $2km\times2km$ grid, L moments statistics, 10 durations from 10 minutes to 72 hours, and a maximum Average Recurrence Interval of 100 years.

• The Journal of the Korea Contents Association
• /
• v.19 no.2
• /
• pp.349-367
• /
• 2019

This paper empirically analyzed the factors of operational efficiency after the quasi-public bus operating system in Busan Metropolitan City. DEA analysis result, for CRS the annual efficiency in 2010 of bus routes that can be transferred to subway lines 1 was the highest. The annual efficiency of bus routes that can be transferred to subway lines 2 shows the largest annual average of 0.923 in 2016 under the CRS average gradually improved over the year. Annual efficiency of subway lines No. 3 and transferable bus routes gradually improved from 2009 to 2015, but declined again in 2016. Among 536 routes for four years on 134 routes per year, 205 routes were found to be inefficient. In order to increase efficiency of the 205 routes, it is suggested that the number of routes should be reduced. In addition, the analysis results on DEA using the Tobit calibration, the most significant factors affecting the operational efficiency index were the time taken, followed by the number of passengers and the number of passengers transferred.

• Journal of Microbiology and Biotechnology
• /
• v.30 no.12
• /
• pp.1862-1869
• /
• 2020

The spread of plasmid-mediated colistin resistance has posed a serious threat to public health owing to its effects on the emergence of pandrug-resistant bacteria. In this study, we investigated the prevalence and characteristics of mcr-1-positive Escherichia coli isolated from retail meat samples in Korea. In total, 1,205 E. coli strains were isolated from 3,234 retail meat samples in Korea. All E. coli strains were subjected to antimicrobial susceptibility testing and were examined for the presence of mcr-1 gene. All mcr-1-positive E. coli (n = 10, 0.8%) from retail meat were subjected to pulse-field gel electrophoresis (PFGE) and whole-genome sequencing (WGS). The transferability of mcr-1 gene was determined by conjugation assays. The mcr-1-positive strains exhibited diverse clonal types. Our mcr-1 genes were located in plasmids belonged to the IncI2 (n = 1) and IncX4 (n = 8) types, which were reported to be prevalent in Asia and worldwide, respectively. Most mcr-1 genes from mcr-1-positive strains (9/10) were transferable to the recipient strain and the transfer frequencies ranged from 2.4 × 10-3 to 9.8 × 10-6. Our data suggest that the specific types of plasmid may play an important role in spreading plasmid-mediated colistin resistance in Korea. Furthermore, our findings suggest that the retail meat may be an important tool for disseminating plasmid-mediated colistin resistance.

• SUVANNABHUMI
• /
• v.10 no.2
• /
• pp.121-142
• /
• 2018

Area studies are sometimes framed as focused on specific localities, rooted in deep linguistic, cultural and historical knowledge, and hence empirically rich but, as a result, as yielding non-transferable/non-translatable findings and hence as theoretically poor. In Europe and North America some social science disciplines like sociology, economics and political science routinely dismiss any reference to local specifics as parochial "noise" interfering with their universalizing pretensions which in reality obscure their own Euro-American parochialism. For more qualitatively oriented disciplines like history, anthropology and cultural studies the inherent non-universality of (geographically constricted) area studies presents a predicament which is increasingly fought out by resorting to philosophical concepts which usually have a Eurocentric pedigree. In this paper, however, I argue that concepts with arguably European pedigree - like religion, culture, identity, heritage and art - travel around the world and are adopted through vernacular discourses that are specific to locally inflected histories and cultural contexts by annexing existing vocabularies as linguistic vehicles. In the process, these vernacularized "universal" concepts acquire different meanings or connotations, and can be used as powerful devices in local discursive fields. The study of these processes offer at once a powerful antidote against simplistic notions of "global"/"universal" and "local," and a potential corrective to localizing parochialism and blindly Eurocentric universalism. I develop this substantive argument with reference to my own professional, disciplinary and theoretical trajectory as an anthropologist and historian focusing on Vietnam, who used that experience - and the empirical puzzles and wonder encountered - in order to develop theoretical interests and questions that became the basis for larger-scale, comparative research projects in Japan, China, India, South Africa, Brazil and Europe. The subsequent challenge is to bring the results of such larger, comparative research "home" to Vietnam in a meaningful way, and thus overcome the limitations of both area studies and Eurocentric disciplines.

• Journal of Embryo Transfer
• /
• v.17 no.1
• /
• pp.67-77
• /
• 2002

This study was carried out to assess the effect of superovulation response and quality of embryos recovered from donor cows after a single subcutaneous injection of FSH dissolved in polyethylene glycol (PEG). Cows were allocated into control and 3 experimental treatment groups. In control, cows were injected intramuscularly 50 mg FSH twice daily for 4 days. Group 1 were injected subcutaneously with a single dose of 400 mg FSH dissolved in 30% PEG solution. Group 2 were injected subcutaneously with a single dose of 200 mg FSH dissolved in 30% PEG solution. Finally in group 3, cows were injected twice 200 mg FSH dissolved in 30% PEG solution by subcutaneous. Superovulation was initiated by injection of FSH between Day 8 and 14 of the estrus cycle (Day 0, the day of estrus), and followed by injection of 25 mg PGF$_2$$\alpha$ at 48 h after first FSH injection. Cows were then artificially inseminated (AI) with semen twice at 48 and 60 h after PGF$_2$$\alpha$ injection. At 7 days after the second AI, embryos collected non-surgically by flushing the uterine horns and were counted and compared morphologically as being transferable and degenerated among different superovulation treatments. Furthermore, progesterone and estradiol -17 $\beta$ in plasma were measured by radioimmunoassay following different treatments at given days All cows of treated groups were observed heat. but control group was showed 77.8%. Superovulation response was observed as 77.8, 87.5, 88.9, and 100% in control, Groups 1, 2 and 3 The mean number of corpus lutea (CL) detected in Group 1 were 19.6, which was, respectively significantly (P<0.05) higher than those of other groups (11.1, 13.4 and 7.6, respectively). However, there did not differ on the mean number of total embryos recovered and of transferable embryos between control and treated groups.

• The Journal of the Korean Society for Microbiology
• /
• v.17 no.1
• /
• pp.21-34
• /
• 1982

One hundred and twenty-one strains each of Escherichia coli isolated from stools of 60 patients who received various antimicrobial drugs in hospital for more than one week and apparently healthy 60 students who have no history of taking antimicrobial drugs during recent one month, were tested for their resistance to 13 antimicrobial drugs. The frequency of resistance strains was highest to tetracycline with 69.2%, and followed by streptomycin(Sm), sulfisomidine(Su), chloramphenicol(Cm), ampicillin(Ap), and carbenicillin(Cb) in the decreasing order, ranging from 61.2% to 39.3%. Strains resistant to kanamycin(Km), cephaloridine(Cr), and trimethoprim(Tp) occupied about one-fourth of strains, and only four strains were resistant either one or more of nalidixic acid, gentamicin and amikacin, and no strain was resistant to rifampicin. The frequency of resistant strains to Cm, Ap, Km, Cr, and Cb was much higher among patient isolates than student strains, but strains resistant to the other drugs showed almost the same frequencies between patient and student isolates. There was a marked difference in average minimum inhibitory concentrations of between resistant and susceptible strains, suggesting that the resistance to drugs is the plasmid origin. Seventy-six percent of strains were resistant to one to 10 drugs tested, and no much difference was observed between strains from patients and students. However, strains resistant to four or more drugs were much more frequently found among patient isolates than student strains, with the increasing tendency of multiply resistant strains among patient isolates following the increase in the number of resistant drugs. The transfer of drug resistance by conjugation was tested and 98 strains(67.5%) among 145 which were resistant to two or more drugs were found to transfer their drug resistance to E. coli. Among 74 strains resistant to 7 or more drugs, all except one transferred the resistance, and the number of strains with transferable resistance decreased, as the number of resistant drugs decrease. A R plasmid from randomly selected p13 strain was tested for the incompatibility group, and the plasmid was classified into Inc F II. R plasmM DNA bands were identified by polyacrylamide gel electrophoresis.

• Reproductive and Developmental Biology
• /
• v.31 no.3
• /
• pp.199-205
• /
• 2007

The present study was carried out to assess the effect of superovulation response and efficiency of embryo production induced with injection of FSH dissolved in polyethylene glycol (PEG) in Hanwoo. Eighty-eight cows were divided into four groups. In group 1, cattle were intramuscularly treated with twice-daily administration of 50mg FSH for 4 days. Group 2 and 3 were subcutaneously single injection of 400mg and 200mg FSH dissolved in 30% PEG, respectively. Group 4 were subcutaneously single injection of 200 mg FSH dissolved in 30% PEG at 7 day after CIDR insertion. The number of corpus luteum (CL) in group 2 resulted in significantly (p<0.05) higher compared to group 1, 3 and 4 (18.5 vs. 11.2, 13.1 and 13.9, respectively). However, the number of total ova $(7.9{\sim}10.4)$, transferable embryos $(3.7{\sim}4.7)$, degenerate embryos $(1.9{\sim}3.5)$ and unfertilized ova $(1.8{\sim}2.7)$ did not differ among treatment groups. No difference was observed in pregnancy rate after transferring the recovered embryos among groups $(36.0{\sim}50.0%)$. In addition, blood progesterone concentrations at embryo recovery did not differ among all groups. In conclusion, although no differences were observed in the number of total ova, transferable embryos and pregnancy rate after transfer, a single injection of reduced dose of FSH (200mg FSH) at 7 day after CIDR insertion is more practical for superovulation treatments than frequent injection because of reduction of stress in Hanwoo and decreases of cost and laber.

• Journal of Embryo Transfer
• /
• v.21 no.2
• /
• pp.147-156
• /
• 2006

The objective of this study was to supply excellent genetic resources to livestock farms by transferring embryos produced by genetically superior Korean cows (Hanwoo). Eighty Hanwoo donors were superovulated with gonadotropin ($Folltrpin^(R)\;or\;Antorin^(R)$) for 4 days combined with or without progesterone releasing intravaginal device (CIDR) insertion. The collected fresh or frozen-thawed embryos were transferred to 226 farm recipients. In this study, the effect of CIDR insertion in combination with gonadotropin ($Folltrpin^(R)$) treatments initiated at the random stage of estrous cycle on embryo production was evaluated and compared to conventional superovulation protocol. Moreover, the effect of gonadotropin ($Antorin^(R)$) dose in CIDR-treated Hanwoo donors on the embryo yield was determined. In addition, the effects of embryos (fresh vs. frozen-thawed), embryo transfer person, seasons and farms on the pregnancy rate were evaluated. In Hanwoo donors, CIDR insertion in combination with $Folltrpin^(R)$ treatments regardless of estrous detection resulted in increased numbers of total ova (6.5 vs. 5.8) and transferable embryos (3.9 vs. 3.2) compared to the conventional superovulation protocol (p<0.01). In CIDR-treated Hanwoo donors, the higher dose of $Antorin^(R)$ (36 vs. 28 mg) resulted in the increased number of transferable embryos (8.3 vs. 5.4, p<0.05). The embryos (fresh 43.9% vs. frozen-thawed 23.1%) and embryo transfer person (53.9 vs. $0{\sim}16.7%$) significantly affected the pregnancy rate after embryo transfer (p<0.01). These results suggest that CIDR-based superovulation protocol may be effectively used for production of superior Hanwoo embryos and, multiple ovulation and embryo transfer in Hanwoo might be effectively applied for livestock improvement if pregmancy rate with frozen-thawed embryos and embryo transfer skill would be improved.