• Journal of the Korean Vacuum Society
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• v.15 no.2
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• pp.139-144
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• 2006

Using scanning tunneling microscopy (STM) measurements, we studied the adsorption of hydrogen on the Si(111)$4{\times}1$-In surface at room temperature. The H atom features are found to be located between the two protrusions in one side of the $4{\times}1$ chain. The adsorbed H preferentially occupies one of the two zigzag In subchains, suggesting that the adsorption of H is influenced by the subsurface structure. The adsorbed H atom induces not only a localized distortion but also perturbs the distant region and results in a period-doubling modulations in the STM images. This H-induced perturbation differs from the Na-Induced perturbation on the same surface.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.3 no.1
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• pp.41-56
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• 1999

Since UV-B radiation measuring networks have not been established, numerical models which calculate the flux from other readily available meteorological measurements may play an important role. That is, such a problem can be solved by using parameterization models such as two stream approximation, the delta-Eddington method, doubling method, and discrete ordinate method. However, most UV-B radiative transfer models have not been validated with measurements, because such models are not intended as practical computational schemes for providing surface estimates of UV-B radiation. The main concern so far has been to demonstrate model sensitivity for cloudless skies. In particular, few have been concerned with real cloud information. Clouds and aerosols have generally been incorporated as constituents of particular atmospheric layers with specified optical depths and scattering properties. The parameterization model presented here is a combination of a detailed radiative transfer algorithm for a coludless sky radiative process and a more approximate scheme to handle cloud effects. The model input data requires a daily measurement of the total ozone amount plus a daily record of the amount and type of cloud in the atmosphere. Measurements for an examination of the models at the Department of Atmospheric Sciences, Pusan National University have been takenfrom February, 1995. These models can be used to calculate present and future fluxes where measurements have not been taken, and construct climatologies for the period before ozone depletion began.

• Journal of the Korean Magnetic Resonance Society
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• v.15 no.2
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• pp.115-127
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• 2011

A newly developed cost-effective approach to prepare $^{15}N/^{13}C$-labeled protein for NMR studies is presented. This method has been successfully applied to isotopically labeling of PTK6 SH2 domain and MTH 1880 protein. The production method generates cell density using a growing media containing $^{15}NH_4Cl$, $^{12}C_6$-D-glucose. Following a doubling time period for unlabeled metabolite exhaustion and then addition $^{13}C_6$-D-glucose into a M9 growing media, the cells are induced. Our results demonstrate that in order to get full incorporation of $^{13}C$, the isotopes are not totally required during the initial growth phase before induction. The addition of small amounts of $^{13}C_6$-D-glucose to the induction phase is sufficient to obtain more than 95% incorporation of isotopes into the protein. Our optimized protocol is two-thirds less costly than the classical method using $^{13}C$ isotope during the entire growth phase.

• Water Engineering Research
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• v.1 no.4
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• pp.267-277
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• 2000

This study reports an examination of the sensitivity of water resources in the Keum River basin to climate change. Assuming a doubling in $CO_2$ concentrations, a cooperative study provided four climate change scenarios for this study, which have been translated into temperature and precipitation scenarios on a basin scale. The study utilized these temperature and precipitation data for each climate change scenario as inputs to the NWS-PC model to generate the corresponding streamflow scenario over the Keum River basin. A reservoir simulation model for the Dae-Chung Dam in the Keum River basin has been developed with an object-oriented simulation environment, STELLA. For each streamflow scenario, the performance of the reservoir was assessed in terms of reliability, resiliency, and vulnerability. Although the simulation results are heavily dependent on the choice of the climate change scenarios, the following conclusions can be clearly concluded: (1) the future streamflow over the Dae-Chung Dam tends to decease during the dry period, which seriously increases competitive water use issues and (2) flood control issues predominate under the $2CO_2$-High case.

• The Journal of Natural Sciences
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• v.6 no.1
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• pp.79-87
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• 1993

In the map of period-doubling bifurcation, stable fixed points bifurcate to $2^n$ fixed points, and in the chaotic region, the chaotic bands merge to 1/$2^n$ bands. In a typical map, the chaotic bands expand to a broad chaotic band during the merging process, so called crisis. In this paper, interior crises appearing during the merging process will be discussed by using our map and will be analyzed the characteristics of the phenomenon by obtaining the Lyapunov Exponents.

• Journal of Information Science Theory and Practice
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• v.4 no.2
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• pp.53-65
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• 2016

The authors in this paper aim to identify the growth of literature on Intellectual Property Rights (IPRs). The research publications on IPRs were downloaded from the Scopus online citation database and the authors found that there were 1,513,138 records contributed globally over a period of 10 years from 2005 to 2014. The distribution of publications based on the year, country, and document type were studied. Relative growth rate (RGR) of the publications and doubling time (T_d) were calculated. Most productive organizations, source titles, and the productive authors on IPR research were studied. Most cited articles in the study area were identified. The results show that a number of publications under the subjects Medicine and Engineering were produced. The developed countries are very active in IPR research and producing publications. It is found that one institution which holds the sixth place among the top 10 most productive institutions belongs to Brazil, a developing country. Two developing countries such as China and India hold second and tenth positions respectively in the top 10 countries contributing literature on IPRs.

• Journal of Korean Society on Water Environment
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• v.25 no.1
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• pp.7-17
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• 2009

Soil and Water Assessment Tool (SWAT) was used to assess the impact of potential future climate change on the water cycle and soil loss of the Daecheong reservoir watershed. A sensitivity analysis using influence coefficient method was conducted for two selected hydrological input parameters and three selected sediment input parameters to identify the most to the least sensitive parameters. A further detailed sensitivity analysis was performed for the parameters: Manning coefficient for channel (Cn), evaporation (ESCO), and sediment concentration in lateral (LAT_SED), support practice factor (USLA_P). Calibration and verification of SWAT were performed on monthly basis for 1993~2006 and 1977~1991, respectively. The model efficiency index (EI) and coefficient of determination ($R^2$) computed for the monthly comparisons of runoffs were 0.78 and 0.76 for the calibration period, and 0.58 and 0.65 for the verification period. The results showed that the hydrological cycle in the watershed is very sensitive to climate factors. A doubling of atmospheric $CO_2$ concentrations was predicted to result in an average annual flow increase of 27.9% and annual sediment yield increase of 23.3%. Essentially linear impacts were predicted between two precipitation change scenarios of -20, and 20%, which resulted in average annual flow and sediment yield changes at Okcheon of -53.8%, 63.0% and -55.3%, 65.8%, respectively. An average annual flow increase of 46.3% and annual sediment yield increase of 36.4% was estimated for a constant humidity increase 5%. An average annual flow decrease of 9.6% and annual sediment yield increase of 216.4% was estimated for a constant temperature increase $4^{\circ}C$.

• Journal of Information Science Theory and Practice
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• v.5 no.2
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• pp.62-74
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• 2017

This study examined the mechanical engineering research output from India, Japan, and South Korea on different parameters including growth, collaboration indices, and activity index. The purpose of the study is to understand the overall development of mechanical engineering through analytical approaches applied on the scholarly outcome of the countries considered for the study. The study focuses on analysing the articles published by India, Japan, and South Korea, and is restricted to articles indexed in the Science Citation Index - Web of Science for the period 2000 to 2014. The ratios of number of paper to citations for India, Japan, and Korea are 20,836: 1,97,679; 24,494: 2,04,393; and 30,578: 2,66,902 respectively for the period 2000-2014. The findings show that there is a decline in Japanese publications in mechanical engineering, whereas other two countries have recorded an increasing trend. While India has tripled its publications in a span of 15 years, South Korea, on the other hand, has doubled its publications in the same span of time. There has been an increasing trend towards collaboration in almost all fields of science and technology. However, the extent of collaboration and their rate of growth varied for one subject to another, one branch to another branch of the same subject, and from one country to another country. The present study analyses the growth of research publications of the mechanical engineering domain including authorship distribution, collaboration indices, prominent journals, and activity index.

• Journal of Korea Water Resources Association
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• v.41 no.11
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• pp.1095-1106
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• 2008

Climate change and global warming are prevalent all over the world in this century and many researchers including hydrologists have studied on the climate change. This study also studied the impact of climate change on streamflows of a basin in Korea. The SWAT model was used to assess the impacts of potential future climate change on the streamflows of the Daecheong Dam Basin. Calibration and validation of SWAT were performed on a monthly basis for the year of 1982-1995 and 1996-2005, respectively. The impact of seven 15-year(1988-2002) scenarios were then analyzed for comparing it to the baseline scenario. Among them, scenario 1 was set to show the result of doubling $CO_2$, scenario 2-6 were set to show the results of temperature and precipitation change, and scenario 7 was set to show the result of the combination of climatologic components. A doubling of atmospheric $CO_2$ concentration is predicted to result in an maximum monthly flow increase of 11 percent. Non-linear impacts were predicted among precipitation change scenarios of -42, -17, 17, and 42 percent, which resulted in average annual flow changes in Daecheong Dam Basin of -55, -24, 25, and 64 percent. The changes in streamflow indicate that the Daecheong Dam Basin is very sensitive to potential future climate changes and that these changes could stimulate the increased period or severity of flood or drought events.

• Clinical and Experimental Reproductive Medicine
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• v.36 no.1
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• pp.23-34
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• 2009

Objectives: Mesenchymal stem cells (MSC) comprise a promising tool for cellular therapy. It is known that long-term in vitro culture of human bone marrow and adipose tissue derived-MSCs lead to a reduction of life span and a change of stem-like characters. The aim of our study was to examine whether stem cell properties of human umbilical cord-derived stem cells (HUC) could be affected by in vitro expansion. Methods: HUC were isolated from human umbilical cord and cultured for 10 passages in vitro. Morphology and population doubling time (PDT) were investigated, and changes of stem cell properties were examined using RT-PCR and immunocytochemistry during serial subcultures. Results: Morphology and PDT of HUC began to change slightly from the 7th passage (p7). Expression level of nestin and vimentin mRNAs increased along with the culture period from p4 until p10. In contrast, expression level of SCF mRNA decreased during the same culture period. Expression level of Oct-4 and HNF-4${\alpha}$ mRNAs was not significantly changed throughout the culture period until p10. Expression level of BMP-4, FGF-5, NCAM and HLA-ABC mRNAs appeared to increase as the culture continued, however, the difference was not significant. Immunocytochemical studies showed that HUC at p3, p6 and p9 positively were stained with antibodies against SSEA-3 and SSEA-4 proteins. Interestingly, staining intensity of HUC for ICAM-1 and HLA-ABC gradually increased throughout the culture period. Intensity against thy-1 and fibronectin antibodies increased at p9 while that against TRA-1-60 and VCAM-1 antibodies began to decrease at p6 until p9. Conclusions: These results suggest that HUC change some of their stem cell characteristics during in vitro culture. Development of culture system might be needed for the maintenance of characteristics.