• Journal of Environmental Science International
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• v.31 no.5
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• pp.431-445
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• 2022

The Gwangju Stream is a major tributary of the Yeongsan River. To maintain environmental and ecological functions in the stream, the flow is secured by natural water from the Mudeung Mountain as well as waters discharged from Lake Juam and the Gwangju sewage treatment plants. A substantial amount of water is supplied into the upper reaches of Gwangju Stream from Lake Juam. To examine the ecological effects of the water input from Lake Juam on the Gwangju Stream, a field survey of phytoplankton community species and an evaluation of water properties was conducted at five stations, from station GJ1 before the inflow to station GJ5 in the lower region. Nutrient levels decreased in the vicinity of the Lake Juam inflow, suggesting that this water inflow can contribute to the reduction of eutrophication in the stream. The phytoplankton community was mainly composed of Bacillariophyceae, Chlorophyceae, and Cyanophyceae, and the community structure was similar to that of the other study sites located near the water inflow regions. The inflow of water from Lake Juam can affect water quality and the phytoplankton community over a limited area, reducing eutrophication and increasing water flow in the Gwangju Stream.

• Economic and Environmental Geology
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• v.46 no.4
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• pp.351-358
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• 2013

Methane burns more clearly than any other fossil fuels. Coalbed methane(CBM) is natural gas contained in coal beds. This gas is usually producted from coal that is either too deep or too poor-quality to be mined commercially. While global coalbed methane resource estimates are rough, they indicate between 84 and 377tcm, which compares with proven natural gas reserves of 180tcm. Coalbed methane resources are currently only produced on a major scale in the United States, Canada, Australia and China. In this study, we analysed total 109 published papers for the CBM during the 1990~2012 periods by the programs of 'web of science'. The results of analysis, the CBM study led by the United States, the follow India and Australia. In subject area(web of sciences), Energy Fuels is 57, Engineering 58 and Geology 41 papers, respectively.

• Atmosphere
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• v.33 no.4
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• pp.343-354
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• 2023

Turbulence produced on roadways is one of the major factors determining the dilution rates at the initial stage of traffic emissions of air pollutants and, thus, the distribution of air pollutants near the roadways. Field experiments were conducted on Gyeongbu Highway, one of the busiest highways in Korea, for 4~7 days in winter, spring, and summer. Two three-dimensional ultrasonic anemometers were installed on both sides of the highway to estimate turbulence intensities (vertical wind fluctuation and kinetic turbulence energy) induced by the roadway. Roadway-induced turbulence consists of three components: structural road-induced turbulence (S-RIT), thermal road-induced turbulence (T-RIT), and vehicle-induced turbulence (VIT). The contribution of T-RIT to the total RIT was insignificant (less than 10%), and the majority of RIT was S-RIT (by the highway embankment) and VIT. In this study, we propose the empirical relationships of VIT as a function of traffic density and wind speed under free-flow traffic conditions. Although this empirical relationship appears to underestimate the VIT, it can be applied to the air quality models easily because the relationship is simple and only needs readily obtainable input variables (wind speed and traffic information).

• Journal of The Korean Society of Agricultural Engineers
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• v.65 no.4
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• pp.25-32
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• 2023

KDS (Korean Design Standard) for agricultural drainage is a planning standard that helps determine the appropriate capacity and type of drainage facilities. The objective of this study was to analyze the inundation of the agricultural basin considering the current design standard and the critical rainfall duration. This study used the rainfall durations of 1-48 hour, and the time distribution method with the Chicago and the modified Huff model. For the runoff model, the NRCS (Natural Resources Conservation Service) unit hydrograph method was applied, and the inundation depth and duration were analyzed using area-elevation data. From the inundation analysis using the modified Huff method with different rainfall durations, 4 hours showed the largest peak discharge, and 11 hours showed the largest inundation depth. From the comparison analysis with the current method (Chicago method with a duration of 48 hours) and the modified Huff method applying critical rainfall duration, the current method showed less peak discharge and lower inundation depth compared to the modified Huff method. From the simulation of changing values of drainage rate, the duration of 11 hours showed larger inundation depth and duration compared to the duration of 4 hours. Accordingly, the modified Huff method with the critical rainfall duration would likely be a safer design than the current method. Also, a process of choosing a design hydrograph considering the inundation depth and duration is needed to apply the critical rainfall duration. This study is expected to be helpful for the theoretical basis of the agricultural drainage design standards.

• Journal of Environmental Science International
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• v.16 no.2
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• pp.219-225
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• 2007

Endocrine disrupting compounds (EDC's) are chemicals that either mimic endogenous hormones interfering with pharmacokinetics or act by other mechanisms. Some endocrine disrupters were reported to be chemical substances that cause apoptosis in cells. A number of reports have indicated that 1,3-DCP, one of the EDC's may act as an endocrine disrupter and also has possible carcinogenic effects. 1,3-DCP, present in commercial protein hydrolysates used for human nutrition, are genotoxic and 1,3-dichloro-2-propanol induced tumors in rats. In the present study, it was investigated whether 1,3-DCP induces ROS generation and apotosis in A549 adenocarcinoma cells. Here we show that 1,3-DCP inhibits the growth of lung cancer cell lines and generates reactive oxygen species (ROS), a major cause of DNA damage and genetic instability, It was investigated that 1,3-DCP increases G1 phase cells after 12 hours, thereafter abruptly draws A549 cells to G0 state after 24 hours by flow cytometric analysis. 1,3-DCP induces p53 and $p21^{Cip1/WAF1}$ activation time- and dose-dependently by 24 hours, while the level $p21^{Cip1/WAF1}$ was decreased after 48 hours. These results suggest that 1,3-DCP, an EDC's generates ROS and regulates genes involved with cell cycle and apoptosis.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.1026-1029
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• 2005

The feasibility of graphoepitaxial growth of compound semiconductors has been studied. Two kinds of substrates were prepared; one is smooth substrate, the other one is a periodic structured substrate. ZnO film was formed on both substrates by thermal evaporation of elemental Zn and natural oxidation of the deposited Zn. Thermal treatment was performed to improve the crystal quality and to investigate the effect of the periodic structure. Atomic force microscopy (AFM) and photoluminescence (PL) were used to characterize the samples. As a result, the improvement of crystallinity as annealing temperature increase, has been observed from both samples. The samples, annealed at 800 $^{\circ}$C, show the best crystal quality in terms of PL linewidth. Also the sample grown on grating structure shows better crystal quality than the sample grown on flat substrate. It implies that the periodic structure affects the crystallinity of the films, and the graphoepitaxy of compound semiconductors is possible by using appropriate surface structure.

• Tissue Engineering and Regenerative Medicine
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• v.15 no.6
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• pp.735-750
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• 2018

BACKGROUND: The major challenge of tissue engineering is to develop constructions with suitable properties which would mimic the natural extracellular matrix to induce the proliferation and differentiation of cells. Poly(${\varepsilon}$-caprolactone)-poly(ethylene glycol)-poly(${\varepsilon}$-caprolactone) (PCL-PEG-PCL, PCEC), chitosan (CS), nano-silica ($n-SiO_2$) and nano-hydroxyapatite (n-HA) are biomaterials successfully applied for the preparation of 3D structures appropriate for tissue engineering. METHODS: We evaluated the effect of n-HA and $n-SiO_2$ incorporated PCEC-CS nanofibers on physical properties and osteogenic differentiation of human dental pulp stem cells (hDPSCs). Fourier transform infrared spectroscopy, field emission scanning electron microscope, transmission electron microscope, thermogravimetric analysis, contact angle and mechanical test were applied to evaluate the physicochemical properties of nanofibers. Cell adhesion and proliferation of hDPSCs and their osteoblastic differentiation on nanofibers were assessed using MTT assay, DAPI staining, alizarin red S staining, and QRT-PCR assay. RESULTS: All the samples demonstrated bead-less morphologies with an average diameter in the range of 190-260 nm. The mechanical test studies showed that scaffolds incorporated with n-HA had a higher tensile strength than ones incorporated with $n-SiO_2$. While the hydrophilicity of $n-SiO_2$ incorporated PCEC-CS nanofibers was higher than that of samples enriched with n-HA. Cell adhesion and proliferation studies showed that n-HA incorporated nanofibers were slightly superior to $n-SiO_2$ incorporated ones. Alizarin red S staining and QRT-PCR analysis confirmed the osteogenic differentiation of hDPSCs on PCEC-CS nanofibers incorporated with n-HA and $n-SiO_2$. CONCLUSION: Compared to other groups, PCEC-CS nanofibers incorporated with 15 wt% n-HA were able to support more cell adhesion and differentiation, thus are better candidates for bone tissue engineering applications.

• Journal of Plant Biotechnology
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• v.37 no.4
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• pp.388-393
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• 2010

Recently, a number of successful research reports are accumulated to increase the carotenoid level in potato tuber such as $\beta$-carotene, precursor of vitamin A and keto-carotenoid like astaxanthin in which is not synthesized in most plants tissue since it does not contain a specific enzyme to add keto-ring in carotenoid molecule. In particular, keto-carotenoids are more interested due to their strong antioxidant activity. Currently, the content of $\beta$-carotene was increased up to 3,600-fold ($47\;{\mu}g/g$ dry weight) when compared to the control potato tuber, parental cultivar for genetic modification. In addition, astaxanthin, one of the major keto-carotenoid was accumulated up to $14\;{\mu}g/g$ dry weight in potato tuber with red color by over expressing the gene encoding $\beta$-carotene ketolase isolated from marine microorganisms. In this article, we summarized carotenogenesis-related genes that have been used for metabolic engineering of carotenoid biosynthetic pathway in potato. Furthermore, strategies for the accumulation of carotenoids and ketocarotenoids in specific potato tuber, bottle necks, and future works are discussed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.219-220
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• 2016

A power management system (PMS) has been an important part in a ship integrated control system. To evaluate a PMS for a liquefied natural gas carrier (LNGC), this research proposes a real-time hardware-in-the-loop simulation (HILS), which is composed of major component models such as turbine generator, diesel generator, governor, circuit breaker, and 3-phase loads on MATLAB/Simulink. In addition, FPGA based control console and main switchboard (MSBD) are constructed in order to develop an efficient control and a similar real environment in an LNGC PMS. A comparative study on the performance evaluation of PMS functions is conducted using two test cases for sharing electric power to consumers in an LNGC. The result shows that the proposed system has a high verification capability for the operating function and failure insertion evaluation as a PMS simulator.

• The Journal of the Korea Contents Association
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• v.15 no.1
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• pp.506-518
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• 2015

Recently there are growing needs and demand to enhance 'Unity of knowledge' as the concept of "Creating new value through integration and convergence" is developing rapidly in many different areas in the society. This also has significant implication to education. Especially, it requires paradigm shift in terms of required capabilities and qualifications for the students with science major. To accommodate this trend, Natural Sciences and Engineering's College has been increasing convergence education which focus on cultivating creative and cooperative learning capabilities as well as acquiring fundamental knowledge of individual majors. However, convergence education developed and implemented by Sciences college or liberal education so far has been mechanical combination of knowledge from different academic fields - not effectively integrated and interdisciplinary education. Given this situation, this research is to develop and propose a "convergence education program based on the development of scientific and cultural contents" as an education tool to enhance capabilities to apply and re-create integrated knowledge as well as acquire and learn existing knowledge. Education program developed in this research aims to achieve two different and sequential capabilities. First is to understand 'Science and Technology' and 'Cultural Archetype' which would be essential and useful to create cultural contents. Second is to develop capabilities to convert this understanding into cultural contents - a storytelling capability. This education program is differentiated in that it defines cultural contents as a medium to converge and integrate science and technology and humanities. By leveraging the concept of cultural content and storytelling, this education program would be able to overcome restrictions of existing interdisciplinary approach. Also, this program would encourage students to try in-depth research and new applications, and develop logical and creative thinking.