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Kyoochul Ha
Geologic Environment Research Division, Korea Institute of Geoscience and Mineral Resources, 124 Gwahak-ro, Yuseong-gu, Daejeon 34132, Korea

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Journal article
Published: 11 August 2021 in Water
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Two kinds of bottled mineral water from wells located in the northern (Baeksansu, BSS) and southern (Baekdusansu, BDS) areas near Mt. Baekdu (Changbai) were collected in order to monitor the chemical compositions of the groundwater near a potential volcanic area. The bottled water was produced between August 2014 and June 2017, and corresponds to the Na-HCO3 water type. The trend in variation of each chemical component between the two bottled waters was different. The BDS bottled water from the southern area of Mt. Baekdu showed a dramatic change in chemical composition during the study period, whereas the BSS bottled water from the northern area did not show any significant change in chemical composition. In particular, the BDS bottled water showed either systematic increases or decreases of chemical components relative to the Cl concentrations. However, the BSS bottled water did not show such trends. It was confirmed that the chemical composition in the groundwater was constant, even though the monitoring period lasted for about two years. Our data indicate that it may be possible to use the chemical composition of the bottle water produced from the groundwater in the volcanic area as a proxy for monitoring the geochemical environmental change of the groundwater aquifer.

ACS Style

Seung-Gu Lee; Dong-Chan Koh; Kyoochul Ha; Kyung-Seok Ko; Youn Soo Lee; Youn-Young Jung; Zhihui Cheng; Shuang-Shuang Chen. Geochemical Implication of Chemical Composition of Mineral Water (Bottled Water) Produced Near Mt. Baekdu (Changbai), Northeast China. Water 2021, 13, 2191 .

AMA Style

Seung-Gu Lee, Dong-Chan Koh, Kyoochul Ha, Kyung-Seok Ko, Youn Soo Lee, Youn-Young Jung, Zhihui Cheng, Shuang-Shuang Chen. Geochemical Implication of Chemical Composition of Mineral Water (Bottled Water) Produced Near Mt. Baekdu (Changbai), Northeast China. Water. 2021; 13 (16):2191.

Chicago/Turabian Style

Seung-Gu Lee; Dong-Chan Koh; Kyoochul Ha; Kyung-Seok Ko; Youn Soo Lee; Youn-Young Jung; Zhihui Cheng; Shuang-Shuang Chen. 2021. "Geochemical Implication of Chemical Composition of Mineral Water (Bottled Water) Produced Near Mt. Baekdu (Changbai), Northeast China." Water 13, no. 16: 2191.

Journal article
Published: 16 January 2021 in Journal of Hydrology: Regional Studies
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Noseong Stream watershed in Nonsan, Chuncheongnam-do, South Korea. This study aims to identify and quantify groundwater inflow to a stream based on the spatial and temporal distributions of 220Rn and 222Rn activities in stream water and groundwater. Groundwater–stream water exchange fluxes were estimated on the basis of 222Rn mass balance approaches under losing and gaining stream conditions, and groundwater inflow type was identified using a spatial survey of 220Rn in stream water. The 222Rn activities at 20 stations along the stream during four sampling campaigns were higher at high altitudes than low altitudes, regardless of the season. At two sections, which appeared to be gaining systems, the groundwater inflow rates were estimated to be 6.5 × 102 and 4.0 × 102 m3 d–1. At another stream section, where groundwater inflow to the stream and stream water leakage into groundwater may alternatingly occur, the groundwater inflow and stream water leakage were 1.5 × 102 and 2.5 × 104 m3 d–1, respectively. A spatial survey of 220Rn along the stream indicates that groundwater may dominantly discharge to the stream water as point sources rather than diffuse seepage.

ACS Style

Yong Hwa Oh; Dong-Chan Koh; Hong-Il Kwon; Youn-Young Jung; Kil Yong Lee; Yoon-Yeol Yoon; Dong-Hun Kim; Hee Sun Moon; Kyoochul Ha. Identifying and quantifying groundwater inflow to a stream using 220Rn and 222Rn as natural tracers. Journal of Hydrology: Regional Studies 2021, 33, 100773 .

AMA Style

Yong Hwa Oh, Dong-Chan Koh, Hong-Il Kwon, Youn-Young Jung, Kil Yong Lee, Yoon-Yeol Yoon, Dong-Hun Kim, Hee Sun Moon, Kyoochul Ha. Identifying and quantifying groundwater inflow to a stream using 220Rn and 222Rn as natural tracers. Journal of Hydrology: Regional Studies. 2021; 33 ():100773.

Chicago/Turabian Style

Yong Hwa Oh; Dong-Chan Koh; Hong-Il Kwon; Youn-Young Jung; Kil Yong Lee; Yoon-Yeol Yoon; Dong-Hun Kim; Hee Sun Moon; Kyoochul Ha. 2021. "Identifying and quantifying groundwater inflow to a stream using 220Rn and 222Rn as natural tracers." Journal of Hydrology: Regional Studies 33, no. : 100773.

Journal article
Published: 29 December 2020 in Water
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This study was conducted to evaluate seasonal groundwater quality due to groundwater pumping and hydrochemical characteristics with groundwater level fluctuations in an agricultural area in Korea. Groundwater levels were observed for about one year using automatic monitoring sensors, and groundwater uses were estimated based on the monitoring data. Groundwater use in the area is closely related to irrigation for rice farming, and rising groundwater levels occur during the pumping, which may be caused by the irrigation water of rice paddies. Hydrochemical analysis results for two separate times (17 July and 1 October 2019) show that the dissolved components in groundwater decreased overall due to dilution, especially at wells in the alluvial aquifer and shallow depth. More than 50% of the samples were classified as CaHCO3 water type, and changes in water type occurred depending on the well location. Water quality changes were small at most wells, but changes at some wells were evident. In addition, the groundwater quality was confirmed to have the effect of saltwater supplied during the 2018 drought by comparison with seawater. According to principal component analysis (PCA), the water quality from July to October was confirmed to have changed due to dilution, and the effect was strong at shallow wells. In the study areas where rice paddy farming is active in summer, irrigation water may be one of the important factors changing the groundwater quality. These results provide a qualitative and quantitative basis for groundwater quality change in agricultural areas, particularly rice paddies areas, along with groundwater level and usage.

ACS Style

Kyoochul Ha; Eunhee Lee; Hyowon An; Sunghyun Kim; Changhui Park; Gyoo-Bum Kim; Kyung-Seok Ko. Evaluation of Seasonal Groundwater Quality Changes Associated with Groundwater Pumping and Level Fluctuations in an Agricultural Area, Korea. Water 2020, 13, 51 .

AMA Style

Kyoochul Ha, Eunhee Lee, Hyowon An, Sunghyun Kim, Changhui Park, Gyoo-Bum Kim, Kyung-Seok Ko. Evaluation of Seasonal Groundwater Quality Changes Associated with Groundwater Pumping and Level Fluctuations in an Agricultural Area, Korea. Water. 2020; 13 (1):51.

Chicago/Turabian Style

Kyoochul Ha; Eunhee Lee; Hyowon An; Sunghyun Kim; Changhui Park; Gyoo-Bum Kim; Kyung-Seok Ko. 2020. "Evaluation of Seasonal Groundwater Quality Changes Associated with Groundwater Pumping and Level Fluctuations in an Agricultural Area, Korea." Water 13, no. 1: 51.

Journal article
Published: 05 May 2019 in Water
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Seismic waves caused by earthquakes can lead to the movement of fresh groundwater and saltwater in coastal aquifers. The groundwater level, temperature, and electrical conductivity in coastal monitoring wells on the volcanic island of Jeju all responded to the 2011 M 9.0 Tohoku-Oki earthquake. As a result of the earthquake, groundwater temperature and electrical conductivity patterns demonstrated freshwater outflow and saltwater inflow through the monitoring wells in multi-layered coastal aquifers. The seismicity also affected the behavior of ocean tides occurring at depth along the multi-layered coastal aquifers. These observations prove that the use of multi-depth systems for monitoring groundwater level, temperature, and electrical conductivity are more effective than single monitoring systems for understanding the exact behavior of multi-layered aquifers as well as efficiently detecting earthquake-induced or anthropogenic impacts on aquifers in coastal, karstic, or volcanic areas.

ACS Style

Byeongho Won; Se-Yeong Hamm; Kue-Young Kim; Kyoochul Ha; Jehyun Shin; Seho Hwang; Soo-Hyoung Lee. Response Analysis of Multi-Layered Volcanic Aquifers in Jeju Island to the 2011 M9.0 Tohoku-Oki Earthquake. Water 2019, 11, 942 .

AMA Style

Byeongho Won, Se-Yeong Hamm, Kue-Young Kim, Kyoochul Ha, Jehyun Shin, Seho Hwang, Soo-Hyoung Lee. Response Analysis of Multi-Layered Volcanic Aquifers in Jeju Island to the 2011 M9.0 Tohoku-Oki Earthquake. Water. 2019; 11 (5):942.

Chicago/Turabian Style

Byeongho Won; Se-Yeong Hamm; Kue-Young Kim; Kyoochul Ha; Jehyun Shin; Seho Hwang; Soo-Hyoung Lee. 2019. "Response Analysis of Multi-Layered Volcanic Aquifers in Jeju Island to the 2011 M9.0 Tohoku-Oki Earthquake." Water 11, no. 5: 942.

Journal article
Published: 23 June 2018 in Water
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This study showed the hydrogeological characteristics of an alluvial aquifer that is composed of sand, silt, and clay layers in a small domain. It can be classified into a lower high-salinity layer and an upper freshwater layer and contains shells and remnant paleo-seawater (average 5000 μS/cm) due to sea level fluctuation. Geological and electrical conductivity logging, a long-term pumping test, and multi-depth water quality measurements were conducted at pumping, injection, and observational wells to evaluate the hydrogeologic properties, identify the optimal recharge rate, and assess artificial recharge. Using a hydraulic test, a large difference in drawdown and salinity appeared at the radially located observational wells because of the difference in hydraulic connectivity between the wells in the small study area. It was concluded that the hydraulic anisotropy and heterogeneity of the alluvial aquifer should be carefully examined when locating an injection well and considering the efficient design of artificial recharge.

ACS Style

Soo-Hyoung Lee; Se-Yeong Hamm; Kyoochul Ha; Yongcheol Kim; Dong-Chan Koh; Heesung Yoon; Sung-Wook Kim. Hydrogeologic and Paleo-Geographic Characteristics of Riverside Alluvium at an Artificial Recharge Site in Korea. Water 2018, 10, 835 .

AMA Style

Soo-Hyoung Lee, Se-Yeong Hamm, Kyoochul Ha, Yongcheol Kim, Dong-Chan Koh, Heesung Yoon, Sung-Wook Kim. Hydrogeologic and Paleo-Geographic Characteristics of Riverside Alluvium at an Artificial Recharge Site in Korea. Water. 2018; 10 (7):835.

Chicago/Turabian Style

Soo-Hyoung Lee; Se-Yeong Hamm; Kyoochul Ha; Yongcheol Kim; Dong-Chan Koh; Heesung Yoon; Sung-Wook Kim. 2018. "Hydrogeologic and Paleo-Geographic Characteristics of Riverside Alluvium at an Artificial Recharge Site in Korea." Water 10, no. 7: 835.

Journal article
Published: 04 May 2017 in Water
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Time series models based on an artificial neural network (ANN) and support vector machine (SVM) were designed to predict the temporal variation of the upper and lower freshwater-saltwater interface level (FSL) at a groundwater observatory on Jeju Island, South Korea. Input variables included past measurement data of tide level (T), rainfall (R), groundwater level (G) and interface level (F). The T-R-G-F type ANN and SVM models were selected as the best performance model for the direct prediction of the upper and lower FSL, respectively. The recursive prediction ability of the T-R-G type SVM model was best for both upper and lower FSL. The average values of the performance criteria and the analysis of error ratio of recursive prediction to direct prediction (RP-DP ratio) show that the SVM-based time series model of the FSL prediction is more accurate and stable than the ANN at the study site.

ACS Style

Heesung Yoon; Yongcheol Kim; Kyoochul Ha; Soo-Hyoung Lee; Gee-Pyo Kim. Comparative Evaluation of ANN- and SVM-Time Series Models for Predicting Freshwater-Saltwater Interface Fluctuations. Water 2017, 9, 323 .

AMA Style

Heesung Yoon, Yongcheol Kim, Kyoochul Ha, Soo-Hyoung Lee, Gee-Pyo Kim. Comparative Evaluation of ANN- and SVM-Time Series Models for Predicting Freshwater-Saltwater Interface Fluctuations. Water. 2017; 9 (5):323.

Chicago/Turabian Style

Heesung Yoon; Yongcheol Kim; Kyoochul Ha; Soo-Hyoung Lee; Gee-Pyo Kim. 2017. "Comparative Evaluation of ANN- and SVM-Time Series Models for Predicting Freshwater-Saltwater Interface Fluctuations." Water 9, no. 5: 323.

Journal article
Published: 07 April 2016 in Water
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This study investigated changes in stream–aquifer interactions during the period shortly after the construction of the Changnyeong-Haman River barrage (CHRB) on the Nakdong River in South Korea. The hydraulic diffusivity (α) and river resistance (R) values at the semipervious stream–aquifer interface were estimated by using a one-dimensional (1-D) analytical solution with Fourier transform (FT). Prior to the application of the 1-D analytical solution, the noise effects on the groundwater levels were removed by using fast Fourier transform and low-pass filtering techniques. Sinusoidal variation of the river stages was applied to the 1-D analytical solution. For the study period, the R values showed a decreasing trend, while the α values showed an increasing trend, and results showed that the average of the median values of flood duration times (td) and flood amplitudes were reduced to 78% and 59%, respectively. Moreover, the ratio of flood peak time to td demonstrated a decreasing tendency after the construction of the CHRB. Hence, it is concluded that the dredging and increase of river-water storage due to CHRB construction enhanced stream–aquifer interactions during the period shortly after the construction of the CHRB.

ACS Style

Yun-Yeong Oh; Se-Yeong Hamm; Kyoochul Ha; Heesung Yoon; Il-Moon Chung. Characterizing the Impact of River Barrage Construction on Stream-Aquifer Interactions, Korea. Water 2016, 8, 137 .

AMA Style

Yun-Yeong Oh, Se-Yeong Hamm, Kyoochul Ha, Heesung Yoon, Il-Moon Chung. Characterizing the Impact of River Barrage Construction on Stream-Aquifer Interactions, Korea. Water. 2016; 8 (4):137.

Chicago/Turabian Style

Yun-Yeong Oh; Se-Yeong Hamm; Kyoochul Ha; Heesung Yoon; Il-Moon Chung. 2016. "Characterizing the Impact of River Barrage Construction on Stream-Aquifer Interactions, Korea." Water 8, no. 4: 137.

Journal article
Published: 24 November 2015 in International Journal of Molecular Sciences
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The potential effects of monotypic and binary metal oxide nanoparticles (NPs, ZnO, NiO, Co3O4 and TiO2) on microbial growth were evaluated in sandy soil collected from artificial recharge sites. Microbial growth was assessed based on adenosine triphosphate (ATP) content, dehydrogenase activity (DHA), and viable cell counts (VCC). Microbial growth based on ATP content and VCC showed considerable differences depending on NP type and concentration, whereas DHA did not significantly change. In general, ZnO NPs showed the strongest effect on microbial growth in all measurements, showing an EC50 value of 10.9 mg/L for ATP content. The ranking (EC50) of NPs based on their effect on microbial growth assessed by ATP content and VCC was ZnO > Co3O4 > NiO > TiO2. Upon exposure to binary NP mixtures, synergistic and additive modes of action were observed for ATP content and VCC, respectively. The ranges of observed (P(O)) and expected (P(E)) activity were 83%–92% and 78%–82% of the control (p-value 0.0010) based on ATP content and 78%–95% and 72%–94% of the control (p-value 0.8813) based on VCC under the tested conditions, respectively. The results indicate that the effects of NP mixtures on microbial growth in the sandy soil matrix were as great, or greater, than those of single NPs. Therefore, understanding the effects of single NPs and NP mixtures is essential for proper ecological risk assessment. Additionally, these findings demonstrate that the evaluation of NP effects may be profoundly influenced by the method of microbial growth measurement.

ACS Style

Kyung-Seok Ko; Kyoochul Ha; In Chul Kong. Effects of Monotypic and Binary Mixtures of Metal Oxide Nanoparticles on Microbial Growth in Sandy Soil Collected from Artificial Recharge Sites. International Journal of Molecular Sciences 2015, 16, 27967 -27977.

AMA Style

Kyung-Seok Ko, Kyoochul Ha, In Chul Kong. Effects of Monotypic and Binary Mixtures of Metal Oxide Nanoparticles on Microbial Growth in Sandy Soil Collected from Artificial Recharge Sites. International Journal of Molecular Sciences. 2015; 16 (11):27967-27977.

Chicago/Turabian Style

Kyung-Seok Ko; Kyoochul Ha; In Chul Kong. 2015. "Effects of Monotypic and Binary Mixtures of Metal Oxide Nanoparticles on Microbial Growth in Sandy Soil Collected from Artificial Recharge Sites." International Journal of Molecular Sciences 16, no. 11: 27967-27977.

Journal article
Published: 14 February 2013 in Geosciences Journal
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The temporal and spatial analyses of rainfall and temperature were conducted for understanding spatial variability and climate trend on Jeju Island. Rainfall data from 1992 to 2009 were used for the spatial analyses, and missing data were adjusted on Mt. Halla and along the northeast coast to reduce uncertainty of spatial variability. In addition, rainfall time series data of both Jeju City and Seogwipo City from 1961 to 2009 were analyzed for a long-term trend and identification of droughts. Mean annual rainfall for the period 1992–2009 shows an area of maximum rainfall centered around Mt. Halla where maximum annual rainfall reaches more than 4,300 mm and mean island rainfall is 2,082 mm. Upward trends in rainfall intensity, magnitude, and dryness conditions at the Jeju City and Seogwipo City from 1961 to 2009 suggest that rainfall has intensified with greater quantities of rainfall occurring over shorter durations, with longer dry periods between storm events. The annual cycle shows a distinct monsoon signature with peak rainfall typically occurring in August. Rainfall seasonality shows a shift in peak rainfall from June, July, and August, to July, August, and September. The most severe droughts in the period 1961–2009 were identified using a 12-month composite SPI. Three severe droughts each lasting around two years were identified over a relatively short nine-year period from 1964–1972.

ACS Style

Alan Mair; Aly I. El-Kadi; Kyoochul Ha; Gi-Won Koh. Temporal and spatial variability of rainfall and climate trend on Jeju Island. Geosciences Journal 2013, 17, 75 -85.

AMA Style

Alan Mair, Aly I. El-Kadi, Kyoochul Ha, Gi-Won Koh. Temporal and spatial variability of rainfall and climate trend on Jeju Island. Geosciences Journal. 2013; 17 (1):75-85.

Chicago/Turabian Style

Alan Mair; Aly I. El-Kadi; Kyoochul Ha; Gi-Won Koh. 2013. "Temporal and spatial variability of rainfall and climate trend on Jeju Island." Geosciences Journal 17, no. 1: 75-85.