• Economic and Environmental Geology
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• v.31 no.1
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• pp.11-20
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• 1998

The effects of the major cations ($Ca^{2+}$, $Mg^{2+}$, $K^+$, $Na^+$), complex-forming anions ($SO_4{^{2-}}$, $HCO_3{^-}$), and solution pH on the adsorption of $^{137}Cs$ and $^{90}Sr$ by kaolinite in groundwater chemistry were investigated. Three-dimensional Kd modelling designed by a statistical method was attempted to compare the relative effect among hydrated radii, charge and concentration of competing cations on the adsorption of Cs and Sr. The modelling results indicate that the hydrated radii of competing cations is the most important factor, and then their charges and concentrations are also important factors in order. The property of zeta potential of kaolinite particles was discussed in terms of the amphoteric reactions of a kaolinite surface affecting the adsorption of Cs and Sr. The ionic strength of competing cations on the adsorption of Cs and Sr exerts a greater effect than the solution pH. The sorption behaviour of Sr on kaolinite is also highly dependent on the concentration of bicarbonate. The speciation of Sr and the saturation state of a secondary phase were thermodynamically calculated by a computer program, WATEQ4F. This indicates that the change in solution pH with the concentration of bicarbonate and the precipitation of a strontianite ($SrCO_3$) are major factors controlling Sr adsorption behaviour in the presence of bicarbonate ion.

• Korean Journal of Agricultural and Forest Meteorology
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• v.17 no.2
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• pp.93-101
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• 2015

This study was conducted to analyze the relationship between tree-ring growth of Quercus acutissima and climatic variables by dendroclimatological method. Annual tree-ring growth data of Quercus acutissima collected by the $5^{th}$ National Forest Inventory (NFI5) were organized to analyze the spatial distribution of the species growth pattern. To explain the relationship between tree-ring growth of Quercus acutissima and climatic variables, monthly temperature and precipitation data from 1950 to 2010 were compared with tree-ring growth data for each county. When tree-ring growth data were analyzed through cluster analysis based on similarity of climatic conditions, four clusters were identified. In addition, index chronology of Quercus acutissima for each cluster was produced through cross-dating and standardization procedures. The adequacy of index chronologies was tested using basic statistics such as mean sensitivity, auto correlation, signal to noise ratio, and expressed population signal of annual tree-ring growth. Response function analysis was conducted to reveal the relationship between tree-ring growth and climatic variables for each cluster. The results of this study are expected to provide valuable information necessary for estimating local growth characteristics of Quercus acutissima and for predicting changes in tree growth patterns caused by climate change.

• Korean Journal of Agricultural and Forest Meteorology
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• v.20 no.3
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• pp.252-261
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• 2018

This study was conducted to develop a method to generate daily maximum and minimum temperatures using monthly data. We analyzed 30-year daily weather data of the 23 meteorological stations in South Korea and elucidated the parameters for predicting annual trend (center value ($\hat{U}$), amplitude (C), deviation (T)) and daily fluctuation (A, B) of daily maximum and minimum temperature. We use national average values for C, T, A and B parameters, but the center value is derived from the annual average data on each stations. First, daily weather data were generated according to the occurrence of rainfall, then calibrated using monthly data, and finally, daily maximum and minimum daily temperatures were generated. With this method, we could generate daily weather data with more than 95% similar distribution to recorded data for all 23 stations. In addition, this method was able to generate Growing Degree Day(GDD) similar to the past data, and it could be applied to areas not subject to survey. This method is useful for generating daily data in case of having monthly data such as climate change scenarios.

• The Journal of Engineering Geology
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• v.27 no.3
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• pp.293-304
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• 2017

This study was performed in order to hydrogeological analysis of aquifer, which is a necessary part for evaluating the efficiency of the combined well and open-closed loops geothermal (CWG) systems. CWG systems have been proposed for the effective utilization of geothermal energy by combining open loop geothermal systems and closed loop geothermal systems. Small aperture CWG systems and large aperture CWG systems were installed at a green house land with water curtain facilities in Chungju City. Aquifer tests include pumping tests and step-drawdown tests were conducted to analyse hydrogeological characteristics of aquifer in the study area. The transmissivity was estimated in the range of $13.49{\sim}58.99cm^2/sec$, and the storativity was estimated in the range of $1.13{\times}10^{-5}{\sim}5.20{\times}10^{-3}$. The geochemical analysis showed $Ca^{2+}$ ion and ${HCO_3}^-$ ion were dominant in groundwater. The Langelier Saturation Index and the Ryznar Stability Index showed low scaling potential of groundwater. In the analysis of vertical water temperature change, the geothermal gradient was estimated as $2.1^{\circ}C/100m$, which indicated the aquifer was enough for geothermal systems. In conclusion, groundwater is rich, can stably use geothermal heat, and it is less likely to cause deterioration of thermal energy efficiency by precipitation of carbonate minerals in study area. Therefore, the study area is suitable for installation of the combined geothermal system.

• Microbiology and Biotechnology Letters
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• v.10 no.4
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• pp.267-273
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• 1982

Among 12 kinds of ginsenosides in ginseng saponin, ginsenoside-Rb$_1$was contained the most abundantly. But ginsenoside-Rd which is similar to ginsenoside-Rb$_1$in structure, was known to be superior to ginsenoside-Rb$_1$pharmaceutically. In order to convert ginsenoside-Rb$_1$into ginsenoside-Rd by microbial enzyme treatment, a Rhizopus sp. was selected among various strais of molds found in rotten ginseng roots. Enzyme was prepared from the extract of wheat bran koji culture by ammonium sulfate precipitation (1.0 sat'd) and succeeding ammonium sulfate fractionation method (0.6-0.9 sat'd). For the purpose of use as substrate, saponins were purified by the several purification steps from alcohol extract of red ginseng roots. We obtained the total saponin which was composed of 36.5% of ginsenoside Rb$_1$, 12.2% of ginsenoside-Rd and other ginsenosides. For increase of ginsenoside-Rb$_1$ component ratio, we also obtained further purified ginsenoside-Rb group saponin containing 54.5% of ginsenoside-Rb$_1$, 1.1% of ginsenoside- Rd and other ginsenosides from purified the total saponin. In the enzymatic reaction system including the total saponin or the ginsenoside-Rb group saponin, we confirmed the specific conversion of ginsenoside-Rb$_1$to ginsenoside-Rd proportionally and no change of any other ginsenoside patterns by thin layer chromatography and high performance liquid chromatography.

• Journal of the Korean Society for Marine Environment & Energy
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• v.3 no.4
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• pp.23-36
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• 2000

Bottom sea waters in eight stations including from inner bay to outer bay to understand the importance of the submarine groundwater discharge for the environmental assessment of Chinhae Bay was collected in August 1999 and January 2000. Generally, /sup 222/Rn is very useful tracer to assess the submarine groundwater discharge because it is 2-4 orders of magnitude more concentrated in groundwater compared to surface water. The /sup 222/Rn activities ranged between about 33 to 182 dpm/100kg within the bay. Higher activities more than 100 dpm/100kg were found at the inner bay. The /sup 226/Ra activities, its parent, however, were little different between stations. /sup 222/Rn activities at the same station varied with season. It suggests that the major source of /sup 222/Rn is not from the bottom sediment, but from the change of submarine groundwater discharge by precipitation. The contents of Cl/sup -/ and SO/sub 4//sup 2-/ in the groundwater of Wonjeon-ri were very high as 1,312 and 369 ppm, respectively, indicating that this groundwater along the Chinhae coast was affected by seawater. Therefore, the submarine groundwater in the inner Bay may discharge to the overlying water. It indicates that these submarine groundwater discharges may play an important role as another important source of nutrients in the Chinhae Bay, because groundwater around the Chinhae Bay showed high concentration of dissolved inorganic nutrients (average , nitrate>174 μM, silicate>262 μM). Therefore, further studies are required to assess the contribution by the submarine groundwater discharge in the biogeochemical processes of the Chinhae Bay.

• Korean Journal of Materials Research
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• v.22 no.1
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• pp.46-53
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• 2012

In this study, mechanical tests and microstructural analyses including TEM analyses with EDX of precipitates in modified 9Cr-1Mo steel were carried out to determine the cause of embrittlement observed after heat-treatment, which limits the usage of the alloy for power plants. Mod. 9Cr-1Mo steel specimens at austenite temperature were quenched to the molten salt baths at $760^{\circ}C$ and $700^{\circ}C$, in which the specimens were kept for 10 min ~ 10 hr with subsequent air-cooling. Impact tests showed that the impact value dropped abruptly when the specimens were kept longer than 30 min at $\sim760^{\circ}C$ reaching to minima in about 1 hr, and then increasing at further retention. The tensile strength of the specimens reached the minimum value without much change afterward, whereas the values of elongation showed the same trend as that of the impact value. The isothermally heat-treated steel at $700^{\circ}C$ also showed a minimum impact value in about 1 hr. These results suggest that the isothermal heattreatment at 760 and $700^{\circ}C$ for about 1 hr induces temporal embrittlement in Mod. 9Cr-1Mo steel. The microstructural examination of all the specimens with extraction replica of the carbides revealed that the specimens with temporal embrittlement had $Cr_2C$, indicating that the cause of the embrittlement was the precipitation of the $Cr_2C$. In addition, TEM/EDX results showed that the Fe/Cr ratio was 0.033 to 0.055 for $Cr_2C$, whereas it was 0.48 to 0.75 for $Cr_{23}C_6$, making the distinction of the $Cr_2C$ and $Cr_{23}C_6$ possible even without direct electron diffraction analyses.

• Journal of Korean Society on Water Environment
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• v.26 no.3
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• pp.507-517
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• 2010

Long-term monitoring was conducted to identify the runoff characteristics of non-point source according to the three forest types (deciduous forest, coniferous forest and mixed forest) in this study. Rainfall events of each deciduous forest, coniferous forest, and mixed forest were 10, 8, 12, respectively. Average runoff depth and coefficients of each forest type were founded to be coniferous forest and were followed by others in turns : deciduous forest, and mixed forest because various conditions (i.e., rainfall property, Antecedent Precipitation Index (API), soil property, slope, and forest management) could change runoff characteristics. In the analysis of the first flush phenomenon, it showed that SS and T-P were sensitive for the first flush phenomenon. The first flush phenomenon of them were showed differently by rainfall intensity, rainfall duration, and amount of rainfall. The research results indicated that range of the Event Mean Concentration (EMC) values in deciduous forest were 0.8~2.4 mg/L for $BOD_5$, 2.0~13.4 mg/L for $COD_{Mn}$, 1.3~2.9 mg/L for DOC, 1.150~3.913 mg/L for T-N, 0.010~0.350 mg/L for T-P and 3.1~291.8 mg/L for SS and in coniferous forest were 0.8~2.2 mg/L for $BOD_5$, 1.9~3.6 mg/L for $COD_{Mn}$, 1.0~2.0 mg/L for DOC, 1.025~2.957 mg/L for T-N, 0.002~0.084 mg/L for T-P and 0.8~5.4 mg/L for SS. Also, range of the EMC values in mixed forest were 1.3~2.3 mg/L for $BOD_5$, 2.4~4.8 mg/L for $COD_{Mn}$, 1.1~2.1 mg/L for DOC, 0.385~2.703 mg/L for T-N, 0.016~0.080 mg/L for T-P and 2.3~30.0 mg/L for SS.

• Journal of Korean Society of Forest Science
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• v.99 no.6
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• pp.908-913
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• 2010

This study analyzed the impact of climatic and topographic factors on tree radial growth of Pinus densiflora and Quercus spp. in central regions of Korea. To find the relationship between annual tree radial growth and climatic factors, we took the core samples from individual trees and measured the tree radial width. On the assumption that the tree radial growth is related to the tree age, we estimated the radial growth by the tree age as an independent variable. Also, we estimated the standard growth, defined as the radial growth of trees aged 30. As results, we found the spatial auto-correlation in the radial growth of the red pine. Moreover, we also found the relationships between climatic and topographic and the standard growth using the GAM (Generalized Additive Model). Increase of temperature has negative impacts on the radial growth of Pinus densiflora, while it has positive impacts on the radial growth of Quercus spp.. On the other hands, increase of precipitation has negative impacts on the radial growth of both species. Lastly, we predicted the spatial distribution changes of Pinus densiflora and Quercus spp. using the temperature increase scenario and the Geographic Information System (GIS) based forest type map. We could predict that Pinus densiflora is more vulnerable than Quercus spp. to climate change so that the habitats of Pinus densiflora will be gradually changed to the habitats of Quercus spp. in eastern coastal and southern regions of Korea after 60 years.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.4
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• pp.1413-1424
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• 2013

Recently, the frequency of severe storms increases in Korea. Severe storms occurring in a short time cause huge losses of both life and property. A considerable research has been performed for the flood control system development based on an accurate stream discharge prediction. A physical model is mainly used for flood forecasting and warning. Physical rainfall-runoff models used for the conventional flood forecasting process require extensive information and data, and include uncertainties which can possibly accumulate errors during modelling processes. ANFIS, a data driven model combining neural network and fuzzy technique, can decrease the amount of physical data required for the construction of a conventional physical models and easily construct and evaluate a flood forecasting model by utilizing only rainfall and water level data. A data driven model, however, has a disadvantage that it does not provide the mathematical and physical correlations between input and output data of the model. The characteristics of a data driven model according to functional options and input data such as the change of clustering radius and training data length used in the ANFIS model were analyzed in this study. In addition, the applicability of ANFIS was evaluated through comparison with the results of HEC-HMS which is widely used for rainfall-runoff model in Korea. The neuro-fuzzy technique was applied to a Cheongmicheon Basin in the South Han River using the observed precipitation and stream level data from 2007 to 2011.