• Journal of Environmental Impact Assessment
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• v.28 no.6
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• pp.507-524
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• 2019

The purpose of this study was to validate the EFDC model for the weir pool of Gangjeong-Goryong Weir located in Nakdong River, and evaluate the effect of flow control and phosphate loading reduction on the water quality and algae biomass by group (Diatom, Green, Cyanobacteria). As a result of model validation using 2018 experimental data,the time series of water level and vertical distribution of water temperature, DO, organic matter, nitrogen, and phosphorus time series were properly simulated. Seasonal fluctuations of algae biomass by group were adequately reproduced, but the deviations between measured and simulated values were significant in some periods. As a result of scenario simulations to control the water level and flow rate, the thermal stratification was resolved as the water level was lowered and the flow rate increased. The flow velocity at which the water temperature stratification was resolved was about 0.1 m/s, which is consistent with the previous study results of Baekje Weir in Geum River. Simulations of the 2Q flow scenario showed that Chl-a decreased by 8.7% and the cell density of diatom and green algae declined. The cell density of cyanobacteria increased, however, because the high concentrations of cyanobacteria in the upstream boundary conditions directly affected downstream due to increased flow velocity. In the scenario simulation of reducing the influent phosphate load concentration (average 0.056 mg/L) to 50%, Chl-a decreased by 13.6%.The results suggest that the upstream algae concentration and phosphorus load reduction should be considered simultaneously with hydraulic control to prevent algal overgrowth of Gangjeong-Goryong Weir.

• The Korean Journal of Malacology
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• v.27 no.2
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• pp.99-105
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• 2011

This study was conducted to compare the species composition of sessile organisms on the artificial substrates of PVC submerged at different time intervals and duration in Jangmok Bay, Geoje Island, southern coast of Korea. Three PVC plates were submerged at one month interval from March to October and retrieved in November, 2007. A mussel, Mytilus galloprovincialis exclusively occupied the artificial substrates submerged from March to April and occurred as a dominant species to July. An ascidian, Styela plicata occurred as a dominant sessile species from May to August. Balanus amphtrite, Bugula sp., and hydrozoans occurred as dominant species on the plates submerged from July to September. There was a mis-match between the peak time of settlement and dominance of sessile organisms due to the interspecies competitions when the PVC plates were retrieved in November. There was no clear relationship between submerged duration and the abundance of sessile organisms due to the different settlement period. M. galloprovincialis seemed to be a strong competitor which could exclude the previous recruiters of macroalgae by overgrowth and occupy the substrate surface and maintain its high population density by preventing the settlement of other species until late autumn. These results suggested that the composition of sessile organisms in vacant hard substrates could be determined by the combined effects of supply-timing of larvae and post-settlement competitions.

• The Journal of the Petrological Society of Korea
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• v.23 no.3
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• pp.197-208
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• 2014

Zircon separated from a biotite schist of the Guryong Group in Odesan area, eastern part of the Gyeonggi Massif in Korea were analysed for SHRIMP U-Pb ages. CL images display composite core-rim structures of the zircon, indicating an in-situ overgrowth of zircon through a high-grade metamorphism. The metamorphic zircon rims give a weighted mean age of $247{\pm}6Ma$. While the detrital zircon cores have zoning patterns and Th/U ratios indicative of a magmatic origin. Among 53 analyses from the cores, 46 data yield near concordant ages which are concentrated at $378{\pm}10Ma$ (n=9), $420{\pm}4Ma$ (n=6) and $1845{\pm}9Ma$ (n=18) with sporadic Neoproterozoic ($687{\pm}9Ma$) to late Archean ($2519{\pm}20Ma$) ages. The age data constraint sedimentation age of protolith of the Guryong Group, so far unknown, as late Paleozoic. The Guryong Group of this study is the first late Paleozoic strata reported from eastern Gyeonggi Massif, and its maximum depositional age (ca 378 Ma) is identical with those of the late Paleozoic strata in the southwestern Ogcheon Belt. The Triassic metamorphic age and abundant middle Paleozoic provenance (361~425 Ma) of the Guryong Group are similar with those reported from the Triassic collisional belt in central China. Thus this study indicates that the Odesan area would be an possible eastward extension of the Triassic collisional belt in central China.

• Journal of Environmental Impact Assessment
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• v.28 no.3
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• pp.245-262
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• 2019

The objectives of this study were to construct a three-dimensional water quality model (EFDC) for the river reach between Chilgok Weir and Gangjeong-Goryong Weir (GGW) located in Nakdong River, and evaluate the effect of hydraulic changes, such as water level and flow velocity, on the control of water quality and algae biomass. After calibration, the model accurately simulated the temporal changes of the upper and lower water temperatures that collected every 10 minutes, and appropriately reproduced changes in organic matter, nitrogen, phosphorus, and cyanobacteria. However, the simulated values were overestimated for the diatoms and green algae cell density, possibly due to the uncertainties of the parameters associated with algae metabolism and the lack of zooplankton predation function in the simulations. As a result of scenario simulation of running the water level of GGW from EL. 19.44 m to EL. 14.90 m (4.54 m drop), Chl-a and algae cell density decreased significantly.In particular,the cyanobacteria on the surface layer, which causes algal bloom, declined by 56.1% in the low water level scenario compared to the existing management level. The results of this study are in agreement with the previous studies that maintenance of critical flow velocity is effective for controlling cyanobacteria, and imply that hydraulic control such as decrease of water level and residence time in GGW is an alternative to limit the overgrowth of algae.

• Journal of Korean Society on Water Environment
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• v.35 no.4
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• pp.316-331
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• 2019

Carbon dioxide($CO_2$) emission from rivers to the atmosphere is a key component in the global carbon cycle. Most of the rivers are supersaturated with $CO_2$. At a global scale, the amount of $CO_2$ emission from rivers is reported to be five-fold greater than that from lakes and reservoirs, but relevant data are rare in Korea. The objectives of this study is to estimate the $CO_2$ net atmospheric flux(NAF) from the upstream of Gangjeong-Goryeong Weir(GGW), Dalseong Weir(DSW), Hapcheon-Changnyeong Weir(HCW), and Changnyeong-Haman Weir(CHW) located in Nakdong River South Korea) using field and laboratory experiments and to apply data mining techniques to develop parsimonious prediction models that can be used to estimate $CO_2$ NAF with physical and water quality variables that can be collected easily. As a result, the study sites were all heterotrophic systems that often released $CO_2$ to the atmosphere, except when the algal photosynthesis was active.The median $CO_2$ NAF was minimum $391.5mg-CO_2/m^2$ day at GGW and maximum $1472.7mg-CO_2/m^2$ day at DSW. The $CO_2$ NAF showed a negative correlation with pH and Chl-a since the overgrowth of the algae consumed $CO_2$ in the water and increased the pH. As the parsimonious multiple regression model and random forest model developed, this study showed an excellent performance with the $Adj.R^2$ value higher than 0.77 in all weirs. Thus, these methods can be used to estimate $CO_2$ NAF in the river even if there is no $pCO_2$ measurement data.

• Korean Journal of Clinical Laboratory Science
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• v.51 no.2
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• pp.164-170
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• 2019

The absorption and release capacities, survival efficiency, and recovery rates of five kinds of transport media were evaluated based on the swab elution method (Quantitative) of CLSI (Clinical and Laboratory Standards Institute) M40-A2. Liquid media showed mostly better results than semi-solid media in the three evaluations. The flocked swabs had better ability to absorption and discharge bacteria than the standard swabs. The liquid medium (S4) had the best survival efficiency. Pneumococcal strains with poor growth had a higher survival efficiency and recovery rate in liquid media (S4, S5). The results of microbial recovery showed that S. pyogenes met all the CLSI standards in all media. S. pneumoniae was inadequate in the semi- solid media (S2, S3) and all the remaining media met the criteria. H. influenzae was unsuitable in semi-solid media (S1, S3) and met the criteria in semi-solid medium (S2) and liquid medium (S4, S5). The viability of the H. influenzae, pneumococcal strain causing respiratory disease, was poor in most media. Overgrowth of P. aeruginosa was observed at room temperature. The combination of liquid medium and flocked swab confirmed the best results in the three evaluation methods.

• Journal of Plant Biotechnology
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• v.49 no.1
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• pp.82-89
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• 2022

In vitro techniques were developed for propagating Vaccinium oldhamii using shoots with apical buds. Explants having an apical bud were cultured on Murashige and Skoog (MS) medium supplemented with 1.0, 2.0, and 5.0 mg/L of each zeatin, thidiazuron, 6-benzylaminopurine (BA), and 6-(γ,γ-dimethylallylamino)purine (2-iP) in order to induce multiple shoots. Among the tested treatments, the 2.0 mg/L of 2-iP proved to be most suited for the multiplication and growth of shoots; the multiple shoot induction rate was 100.0%, the average number of shoots was 7.4 per explant, and the average shoot length was 51.7 mm. The in vitro elongated shoots were rooted on half-strength MS medium containing various concentrations of indole-3-butyric acid (IBA) and 1-naphthaleneacetic acid (NAA). However, overall callus overgrowth was observed in all treatments and resulted in necrosis and abnormal shoot growth in root formation. A low concentration (0.5 mg/L) of IBA was appropriate for normal root development and the in vitro rooting rate was 30%. Ex vitro treatments on root formation using various concentrations of IBA with Talc powder and two types of rooting substrates (Flexi-Plugs or Horticultural soil) were examined. The ex vitro rooting rate (80%) and length of roots (32.9 mm) were obtained when the cut ends of the shoots were treated with 1.0 mg/L IBA and cultivated in Horticultural soil for 2 months. These findings suggest that ex vitro rooting is the more effective method for improving root formation in Vaccinium oldhamii than in vitro rooting.

• Journal of Practical Agriculture & Fisheries Research
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• v.23 no.1
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• pp.59-66
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• 2021

This study aimed to a basic research for the development of dye-sensitized solar cells that the wavelength band required for crop growth is passed, and the wavelength band that is not necessary for crop growth can be used for the generation of electricity. The transmissivity according to the illuminance was about 10% higher in the Blue filter and the Green filter than in the Red filter, but the transmissivity according to the PPFD was about 10% higher in the Red filter and the Blue filter than in the Green filter. In addition, the greenhouse attached with 30% infrared blocking filter was predicted to have a lower air temperature than other greenhouses, but it was investigated that there was no significant difference. Therefore, it was investigated that the application of the infrared cut filter would not be appropriate in a greenhouse that controls the temperature by opening a window. As a result of investigating, it was found that the Green and Blue filter greenhouses had the severe overgrowth and the stems grew weaker. The fresh weight of paprika in the infrared blocking filter greenhouse was the highest at 678.9g, and the growth of Red filter and the control greenhouses was relatively poor. Photosynthetic rate, amount of transpiration, and stomatal conductivity were the infrared blocking filter and control greenhouse higher than others. On the other hand, the water use efficiency did not show a big difference.

• Journal of the Korean Society of Radiology
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• v.16 no.5
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• pp.559-565
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• 2022

In this study, we intend to develop a granulation tissue formation model. As a pilot experiment, a contrast agent was injected into the pylorus in 3 rats, the normal pylorus lumen size was confirmed, and a stent was placed. Stent migration was confirmed in to the duodenum within 1 week. In this experiment, stent was sutured and fixed to induce granulation tissue formation after gastrostomy under a fluoroscopic guidance. Twenty rats were divided into Healthy Group / Gastrostomy Group. After anesthesia of the Gastrostomy Group, an abdominal incision was performed, and gastrostomy was performed under a fluoroscopic guidance, and a stent was placed into the pylorus. In order to prevent stent migration due to peristalsis, suture between the pylorus and the proximal end of the stent was performed. Postoperative behavior and weight changes were monitored daily. Four weeks after surgery, gastrointestinal fluoroscopy imaging was performed and rats were sacrifices. To evaluate the degree of granulation formation, the stent was sectioned transversely. Gastrostomy group was statistically significantly higher than Healthy Group in granulation area ratio (all p<.001). In conclusion, it is considered that the level of tissue overgrowth formation for preclinical evaluation of the pylorus stricture model through gastrostomy is appropriate as a research evaluation tool.

• Journal of Korea Water Resources Association
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• v.56 no.6
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• pp.373-380
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• 2023

Due to abnormal climate phenomena and climate change in Korea, overgrowth of algae in rivers and reservoirs occurs frequently. Algae in rivers are classified into green algae, blue-green algae, diatom, and other types, and some species of blue-green algae cause problems due to odor and the discharge of toxic substances. In Korea, an algae alert system is in place, and it is issued based on the number of harmful blue-green algae cells. Thus, measuring harmful blue-green algal blooms is very important, and currently, the analysis method of algae involves taking field samples and determining the cell count of green algae, blue-green algae, and diatoms through algal microscopy, which takes a lot of time. Recently, the analysis of algae concentration through Phycocyanin, an alternative indicator for the number of harmful algae cells, has been conducted through remote sensing. However, research on the analysis of the number of blue-green algae cells is currently insufficient. In this study, we water samples for algal analyses were collected from river and counted the number of blue-green algae cells using algae microscopy. We also obtained the Phycocyanin concentration using an optical sensor and acquired algae spectra through a hyperspectral sensor. Based on this, we calculated the equation for estimating blue-green algae cell counts and estimated the number of blue-green algae cells.