• Tunnel and Underground Space
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• v.26 no.2
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• pp.68-86
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• 2016

Understanding the frictional properties of rock discontinuities is crucial to ensure the stability of underground structures. In particular, the frictional behavior at depth depends on the complex interaction among mechanical, hydraulic, thermal and chemical characteristics and their coupled effects. In this study, a series of shear tests were carried out in a triaxial compression chamber to investigate the shearing behavior of saw-cut granite surface and rough shear surface of synthetic rocks. The test results were analyzed using Coulomb's shear strength criterion. The frictional behavior of saw-cut granite surface showed little variation at different confining, water pressures and temperature conditions, however in case of synthetic rocks, the frictional behavior showed different trend depending on normal stress level. In addition, the variation of stiffness and dilation at different testing conditions were analyzed, and the stiffness and dilation showed little variation at different water pressures and temperature conditions.

• The Journal of Engineering Geology
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• v.26 no.4
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• pp.531-549
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• 2016

The purpose of this study is to analyze the relationship of hydrochemistry, geology, fault with occurrence of uranium and radon-222 from the groundwater in the Yeongdong area. In this study, 49 groundwater and 4 surface water samples collected in the study area were collected on two separate occasions. The surface radioactivities were measured at 40 points to know the relationship between the occurrence of uranium in groundwater and surface geology. The chemical composition of groundwater showed three types : $Ca-HCO_3$, $Na-HCO_3$ and $Ca-HCO_3(SO_4,\;NO_3)$. Two groundwater of 49 samples exceeded the maximum contaminant levels of uranium, $30{\mu}g/L$, proposed by the Ministry of Environment of Korea and 11 groundwater of 40 samples for Rn-222 concentrations exceeded the 148 Bq/L maximum contaminant level of US EPA. Most of unsuitable groundwater are located in the geological boundary related with the biotite gneiss and the surface radioactivities of rock samples showed no relationship with groundwater geochemical constituents. The strike-slip fault, Youngdong fault, is $N45^{\circ}E$ direction and the high concentrations of uranium in upper part of fault, consisted of granite and granitic gneiss are detected but in lower part, consisted of metamorphic sedimentary rock are not detected. It suggests that the natural radioactive concentrations are related with the geologic characteristics and the migration and diffusion of natural radioactive materials are affected by the fault.

• Journal of the Korean Society of Groundwater Environment
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• v.5 no.4
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• pp.177-191
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• 1998

For various kinds of waters including surface water, shallow groundwater (＜70 m deep) and deep groundwater (500∼810 m deep) from the Pungki area, an integrated study based on hydrochemical, multivariate statistical, thermodynamic, environmental isotopic (tritium, oxygen-hydrogen, carbon and sulfur), and mass-balance approaches was attempted to elucidate the hydrogeochemical and hydrologic characteristics of the groundwater system in the gneiss area. Shallow groundwaters are typified as the 'Ca-HCO$_3$'type with higher concentrations of Ca, Mg, SO$_4$and NO$_3$, whereas deep groundwaters are the 'Na-HCO$_3$'type with elevated concentrations of Na, Ba, Li, H$_2$S, F and Cl and are supersaturated with respect to calcite. The waters in the area are largely classified into two groups: 1) surface waters and most of shallow groundwaters, and 2) deep groundwaters and one sample of shallow groundwater. Seasonal compositional variations are recognized for the former. Multivariate statistical analysis indicates that three factors may explain about 86% of the compositional variations observed in deep groundwaters. These are: 1) plagioclase dissolution and calcite precipitation, 2) sulfate reduction, and 3) acid hydrolysis of hydroxyl-bearing minerals(mainly mica). By combining with results of thermodynamic calculation, four appropriate models of water/ rock interaction, each showing the dissolution of plagioclase, kaolinite and micas and the precipitation of calcite, illite, laumontite, chlorite and smectite, are proposed by mass balance modelling in order to explain the water quality of deep groundwaters. Oxygen-hydrogen isotope data indicate that deep groundwaters were originated from a local meteoric water recharged from distant, topograpically high mountainous region and underwent larger degrees of water/rock interaction during the regional deep circulation, whereas the shallow groundwaters were recharged from nearby, topograpically low region. Tritium data show that the recharge time was the pre-thermonuclear age for deep groundwaters (＜0.2 TU) but the post-thermonuclear age for shallow groundwaters (5.66∼7.79 TU). The $\delta$$\^$34/S values of dissolved sulfate indicate that high amounts of dissolved H$_2$S (up to 3.9 mg/1), a characteristic of deep groundwaters in this area, might be derived from the reduction of sulfate. The $\delta$$\^$13/C values of dissolved carbonates are controlled by not only the dissolution of carbonate minerals by dissolved soil CO$_2$(for shallow groundwaters) but also the reprecipitation of calcite (for deep groundwaters). An integrated model of the origin, flow and chemical evolution for the groundwaters in this area is proposed in this study.

• Asian Journal of Turfgrass Science
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• v.24 no.2
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• pp.205-210
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• 2010

This study was conducted to investigate the effect of the mixed ratio of the soil amendments, peat, humate, peatmoss and zeolite, on the soil physicochemical properties. The mixed ratios of soil amendments were 0%, 3%, 5%, 7% and 10% (v/v) incorporated with sand which met to the USGA (United State of Golf Association) recommendation. It was measured pH, EC and CEC as a chemical properties. Porosity, capillary porosity, air-filled porosity, bulk density and hydraulic conductivity were also measured to analyze the changes of physical properties. Chemical properties were significantly different by mixture ratios of peat, humate, peatmoss and zeolite. When the results were applied to the USGA standard of the soil physical properties, the optimum mixture ratios of peat, humate and peatmoss were 5%, 3% and 7%, respectively. Air-filled porosity was factor involved in soil physical properties by blending with soil amendments and it was affected on volume of porosity and hydraulic conductivity. To analyze the corelation of mixture ratio versus to physical characters, the ratio of peat and peatmoss was significantly related to capillary porosity and hydraulic conductivity (P<0.05), that of humate hydraulic conductivity (P<0.01), and that of zeolite air-filled porosity and volume of porosity (P<0.05). These results could be used as a basic data for construction USGA sand green.

• Applied Chemistry for Engineering
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• v.30 no.5
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• pp.627-632
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• 2019

In this study, Laminaria japonica was used as a substrate for a mixed aerobic microbial consortium. Laminaria japonica is well-known as a representative brown algal biomass possessing advantages of cheap cost, and high productivity and carbohydrate content. A biological saccharification system was established by inoculating and enriching the mixed aerobic microbial consortium. Production of the soluble carbohydrate and reducing sugar at different hydraulic retention times (HRT) was observed. The efficiency of saccharification increased according to the decrease of HRT. The maximum saccharification yield in a continuous biological pretreatment process was 17.96 and 4.30 g/L/day for the soluble carbohydrate and reducing sugar, respectively at the HRT of 1 day. In contrast, the staccharification yield decreased drastically at the HRT of 0.5 day. Experimental results indicate that Laminaria japonica is a promising material for the production of useful products, in particular for the saccharification through a biorefinery process. It can thus be concluded that a continuous biological pretreatment process using a mixed cultivation system can be successfully employed for the biorefinery technology.

• Korean Journal of Heritage: History & Science
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• v.45 no.1
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• pp.102-121
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• 2012

The purpose of this study is to verify homoteneity of soil and earthenwares and identify firing temperature of earthenwares excavated from Yeoncheon Hapsuri: two earthenwares of the New Stone Age(YCP-1, YCP-2); two of the Bronze Age(YCP-3, YCP-4); and four of the Three States Age(YCP-4~8). The comparative analysis of soil (YCRM) and the earthenwares displays that soil geochemical patterns were similar to YCP-1, YCP-3, YCP-5, YCP-6, YCP-7 and YCP-8. On the other hand, YCP-2 and YCP-4 did not show the similarity to the one of soil because they had been enriched with MgO by contained talc and chlorite. Based on the absorption rate, specific gravity, structural characteristics and XRD analysis, firing temperature has been estimated: for YCP-7 and YCP-8 was $870^{\circ}C$ or over; for YCP-2 and YCP-4 $800^{\circ}C$ or below; and for YCP-1, YCP-3, YCP-5 and YCP-6 between 800 and $870^{\circ}C$. Mineralogical analysis displays that the geochemical pattern of the soil is coincide with the one around Yeoncheon Hapsuri site, which also shows similarity to the one of earthenwares. Such result persuades that the excavated earthenwares were produced with the soils within the precinct of the archaeological sites.

• The Journal of Engineering Geology
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• v.14 no.3 s.40
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• pp.259-272
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• 2004

The purpose of this study is to investigate the effect of hydrochemical variation of groundwater on the gas tigtness in an unlined oil storage cavern. The groundwater chemistry is greatly influenced by the seawater mixing, the water curtain and the dissolution of grounting cements. The chemical composition of groundwater greatly varies ac-cording to both the location of monitoring wells and the sampling period. Most of groundwater shows alkaline pH and high electrical conductivity. The chemical types of groundwater show the dominant order as follows : Na-Cl type > Ca-Cl type > $Ca-HCO_3(CO_3)$ type. Thermodynamic equilibrium state between chemical composition of groundwater and major minerals indicates that carbonate minerals except clay minerals can be precipitated as a secondary mineral. It means that the secondary precipitates can not greatly exerts the clogging effect into fracture aperture in rock mass around oil storage cavern. The content of total organic carbon (TOC) shows a slightly increasing trend from initial stage to late stage. The $EpCO_2$ was computed so as to assess the gas contribution on the $CO_2$ in groundwater. The $EpCO_2$ of 0$\~$41.3 indicates that the contribution of oil gas on $CO_2$ pressure in groundwater system can be neglected.

• The Journal of Engineering Geology
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• v.14 no.4 s.41
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• pp.469-485
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• 2004

The purpose of this study is to investigate the hydrochemical characteristics of groundwater in the Umsung area, and to elucidate the effect of host rock type, well depth and mineralization zone on the groundwater chemistry. The geology of the study area consists of Jurassic granite and Cretaceous sedimentary rocks, which are bounded by a fault. Most of shallow groundwaters exploited in the Jurassic granite area are used for agricultural purpose, whereas the deep groundwaters in the Cretaceous sedimentary rocks are used for a drinking water. The shallow groundwater shows weak acidic pH, the electrical conductivity ranging from $142\;to\;903\;{\mu}S/cm$, and the chemical type of $Ca-HCO_3\;to\;Ca-Cl(SO_4,\;NO_3)$. A few of shallow groundwaters are contaminated by nitrate, and show high concentration of Fe, Mn and Zn, that reflects the effect of a mineralization zone. The deep groundwater shows neutral to weak alkaline pH, higher electrical conductivity than that of shallow groundwater, and the chemical type of $Ca-HCO_3$. The seepage water from the abandoned mines does not have the characteristics such as acidic pH, high concentration of heavy metals and high sulfate content. The hydrogen and oxygen isotopes of groundwater indicates an altitude effect of the recharge area between deep groundwater and shallow groundwater. In conclusion, the chemical composition of groundwater complicately reflects the effects of their host rocks, well depth, agricultural activity and mineralization zone in the study area.

• Membrane Journal
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• v.22 no.4
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• pp.235-242
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• 2012

Ammonium perchlorate (AP) is primarily derived from the process of liquid incineration treatment when dismantling a solid rocket propellant. A series of batch dead-end nanofiltration (NF) and reverse osmosis (RO) membrane experiments were conducted to explore the retention mechanisms of AP under various hydrodynamic and solution conditions. Low levels of silicate type of siloxane had been detected through the GC/MS and FTIR analysis of liquid solutions extracted from solid ammonium perchlorate composite propellant (APCP). It is indicated that NF/RO membranes fouling in the presence of APCP was mainly attributed to the AP interactions because the concentration of silicate type of siloxane was negligible compared to that of AP. The osmotic pressure of AP was presumably resulted in the flux declines ranging from 13 to 17% in the case of the application of low-pressure (551 and 896 kPa for NF and RO) compared to those in application of high-pressure. The retention of AP by NF/RO membranes significantly varied from approximately 10 to 70% for NF and 26 to 87% for RO, depending on the operating and solution water chemistry conditions. The results suggested that retention efficiency of AP was fairly increased by reducing concentration polarization (i.e. application of low-pressure and stirring speed of 600 rpm) and increasing the pH of a solution. The result of this study was also consistent with the previous modeling of 'solute mass transfer of NF/RO membranes' and demonstrated that hydrodynamic and solution water chemistry conditions are to be a key factor in the retention of AP by NF/RO membranes.

• Journal of the Korean earth science society
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• v.23 no.6
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• pp.474-485
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• 2002

The object of this study is to investigate the contamination degree and the interpretation of sea water intrusion phenomena with hydrogeochemical and hydrogen-oxygen stable isotope of coastal aquifer in the Gogum area, Korea. The physical characteristics of groundwaters is the neutral pH condition and transitional Redox environments, and groundwater is affected by sea water & surface water. The chemical properties of groundwaters are showing an increase in contamination owing to the sea water intrusion, waste water from the surface and agricultural chemicals. In the case of chloride, 6 samples of the groundwater in the study area are in excess of the drinking water standard. The Piper diagram shows the contamination in GG-4 and 14 by sea water intrusion. GG-3, 7 and 13 dominate the Na-HCO$_{3}$ type water and regional (GG-14) is indicated to dominate the Na-Cl type water such as sea water. According to the Sl (saturation index), sea water is oversaturated with respect to calcite and dolomite, GG-3, 14 and 18 are approaching the saturation state. The hydrogen-oxygen stable isotope ratio of groundwaters originates in the meteoric water, and groundwaters of GG-1, 5 and 14 display high oxygen isotope value due to surface water trespass and sea water intrusion. The result of this study, GG-14 is contaminated by sea water intrusion, groundwaters expected GG-3, 7 and 13 is in progress to artificial pollution and sea water intrusion.