• Economic and Environmental Geology
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• v.37 no.5
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• pp.569-583
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• 2004

The rock properties of the West pagoda in the Gameunsaji temple site are composed mainly of dark grey porphyritic granodiorite with medium grained equigranular texture and developed with small numerous dioritic xenoliths. These xenoliths occurred with small holes due to different weathering processes. As a weathering results, the rock properties of this pagoda occur wholly softened to physical hardness because of a complex result of petrological, meteorological and biological causes. Southeastern part of the pagoda deteriorated seriously that the surface of rock blocks showed partially exfoliations, fractures, open cavities in course of granular decomposition of minerals, sea water spray and crystallization of salt from the eastern coast. The Joint between blocks has small or large fracture cross each other, contaminated and corrupted for inserting with concrete, cement mortar, rock fragments and iron plates, and partially accelerated coloration and fractures. There are serious contamination materials of algae, fungus, lichen and bryophytes on the margin and the surface on the roof stone of the pagoda, so it'll require conservation treatment biochemically for releasing vegetation inhabiting on the surface and the discontinuous plane of the blocks because of adding the weathering activity of stones and growing weeds naturally by soil processing on the fissure zone. Consisting rock for the conservation and restoration of the pagoda would be careful choice of new rock properties and epoxy to reinforce for the deterioration surfaces. For the attenuation of secondary contamination and surface humidity, the possible conservation treatments are needed.

• Economic and Environmental Geology
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• v.43 no.2
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• pp.137-148
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• 2010

The Myoungbong mine located in Boseong-gun, Jellanamdo consists of Au-Ag bearing quartz veins which filled the fissures of Bulguksa granitic rocks of Cretaceous. The tailings obtained from the Myungbong mine were used to investigate the effects of various processes, such as oxidation of primary sulfides and formation(alteration) of secondary and/or tertiary minerals, on arsenic immobilization in tailings. This study was conducted via both mineralogical and chemical methods. Mineralogical methods used included gravity and magnetic separation, ultrasonic cleaning, and instrumental analyses(X-ray diffractometry, energy-dispersive spectroscopy, and electron probe microanalyzer) and aqua regia extraction technique for soils was applied to determine the elemental concentrations in the tailings. Iron (oxy)hydroxides formed as a result of oxidation of tailings were identified as three specific forms. The first form filled in rims and fissures of primary pyrites. The second one precipitated and coated the surfaces of gangue minerals and the final form was altered into yukonites. Initially, large amounts of acid-generating minerals, such as pyrite and arsenopyrite, might make the rapid progress of oxidation reactions, and lots of secondary minerals including iron (oxy)hydroxides and scorodite were formed. The rate of pH decrease in tailings diminished, in addition, as the exposure time of tailings to oxidation environments was prolonged and the acid-generating minerals were depleted. Rather, it is speculated that the pH of tailings increased, as the contribution of pH neutralization reactions by calcite contained in surrounding parental rocks became larger. The stability of secondary minerals, such as scorodite, were deteriorated due to the increase in pH, and finally arsenic might be leached out. Subsequently, calcimn and arsenic ions dissociated from calcites and scorodites were locally concentrated, and yukonite could be grown tertiarily. It is confirmed that this tertiary yukonite which is one of arsenate minerals and contains arsenic in high level plays a crucial role in immobilizing arsenic in tailings. In addition to immobilization of arsenic in yukonites, the results indicate that a huge amount of iron (oxy)hydroxides formed by weathering of pyrite which is one of typical primary minerals in tailings can strongly control arsenic behavior as well. Consequently, this study elucidates that through a sequence of various processes, arsenic which was leached out as a result of weathering of primary minerals, such as arsenopyrite, and/or redissolved from secondary minerals, such as scorodite, might be immobilized by various sorption reactions including adsorption, coprecipiation, and absorption.

• Journal of Korean Society of Water and Wastewater
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• v.27 no.6
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• pp.689-701
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• 2013

Bacterial growth and corresponding consumption of carbon and phosphorus were examined in which tap water samples containing a very low concentration of free chlorine were supplemented with organic carbon and/or phosphorus. The experiments were performed in a fed-batch mode under a controlled temperature of $20^{\circ}C$. In the phosphorus alone-added water, there was no significant increase in bacterial numbers measured as heterotrophic plate count (HPC) in the bulk water. However, bacterial growth was stimulated by the addition of carbon (e.g., bulk HPC levels increased to $10^3CFU/mL$) and further stimulated by the combined addition of carbon and phosphorus (e.g., bulk HPC to $10^5CFU/mL$). The same effects were observed in biofilm HPC and biomass formed on polyethylene (PE) slide surfaces. In the water where organic carbon and phosphorus were added together, the highest biofilm HPC and biomass (measured as extracellular polymeric substance components) densities were observed which were $7.6{\times}10^5CFU/cm^2$ and $5.3{\mu}g/cm^2$, respectively. In addition to the bacterial growth, additions of organic carbon and/or phosphorus resulted in different bacterial carbon-to-phosphorus (C/P) consumption ratios. Compared to a typical bacterial C/P consumption ratio of 100:1, a higher C/P ratio (590:1) occurred in the carbon alone-added water, while a lower ratio (40:1) in phosphorus alone-added water. Comparative value (80:1) of C/P ratio was also observed in the water where organic carbon and phosphorus were added together. At the given experimental conditions, bacterial growth was deemed to be more sensitive to microbially available organic carbon than phosphorus. The effect of phosphorus addition, which resulted in a lower C/P consumption ratio, seemed to be tightly associated with the presence of microbially available organic carbon. These results suggested that the control of extrinsic carbon influx seemed to be more important to minimize bacterial regrowth in drinking water system, since even low content of phosphorus naturally occurring in drinking water was enough to allow a bacterial growth.

• Korean Journal of Food Science and Technology
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• v.23 no.5
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• pp.554-560
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• 1991

The physicochemical properties of Korean yam starches (D. aimadoimo, D. batatas and D. japonica) were investigated. The mean granular size of starches were 23.5 μm for D. aimadoimo, 23.9 μm for D. batatas and 18.2 μm for D. japonica. Amylose content, blue value and water binding capacity was $29{\sim}33%,\;0.42{\sim}0.51%\;and\;109.9{\sim}118.3%$, respectively. The optical transmittance of 0.3% (dry basis) yam starch suspensions were increased at $70{\sim}75^{\circ}C$ and D. japonica showed typical two-step transmittance curve. The swelling power and solubility patterns increased over $60^{\circ}C$, and D. aimadoimo was the highest values. Amylogram patterns of 5% (dry basis) yam starch suspensions, determined by Brabender amylograph, were similar to that of yam flours and the viscosity of D. aimadoimo had 630 BU, which was about 5 times higher than 130 BU for D. batatas and D. japonica. Observation under scanning electron microscope lefted marks of resistance to glucoamylase because these surfaces were similar to the natural granules. In rates of solubiliazation by dimethyl sulfoxide, D. aimadoimo showed the highest value. (3-Amylolysis limits of yam starches and their amylose were $71.8%{\sim}75.5%\;and\;90.2{\sim}92.1%$, respectively. Gel filtration patterns of debranched amylopectin by pullulanase were divided into 3 peaks. The weight ratios of peak III to peak II in yam starches were $2.15%{\sim}2.42%$.

• Korean Journal of Food Science and Technology
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• v.30 no.5
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• pp.1189-1196
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• 1998

Extraction conditions were optimized using response surface methodology for preparing high-quality ethanol extracts from cultivated Chrysanthemum petals. A fractional factorial design was applied to investigate effects of solvent ratio to sample $(X_1)$, ethanol concentration $(X_2)$ and extraction time $(X_3)$ at $60^{\circ}C$ on dependent variables of the extract properties, such as yellow color $(Y_1)$, carotenoids $(Y_2)$, soluble solids $(Y_3)$, phenolic compounds $(Y_4)$, electron donating ability $(Y_5)$, sensory color $(Y_6)$ and sensory aroma $(Y_7)$. Second-order models were employed to generate 3-dimensional response surfaces for dependent variables and their coefficients of determination $(R^2)$ were ranged from 0.8063 to 0.9963. Optimum extraction conditions for each variable were 115 mL/g, 97%, 18 hr in yellow color, 145 mL/g, 50%, 12 hr in carotenoids, 147 mL/g, 48%, 17 hr in soluble solids, 116 mL/g, 68%, 17 hr in phenolic compounds, 110 mL/g, 98%, 14 hr in electron donating ability, 101 mL/g, 48%, 54 hr in organoleptic color and 109 mL/g, 54%, 4 hr in organoleptic aroma, respectively. The range of optimum conditions at 16hr extraction for maximized characteristics of ethanol extracts was $103{\sim}122\;mL/g$ and $64{\sim}78%$. Predicted values at the optimum condition agreed with experimental values.

• Korean Journal of Agricultural and Forest Meteorology
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• v.13 no.4
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• pp.176-184
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• 2011

Cold air on sloping surfaces flows down to the valley bottom in mountainous terrain at calm and clear nights. Based on the assumption that the cold air flow may be the same as the water flow, current models estimate temperature drop by regarding the cold air accumulation at a given location as the water-like free drainage. At a closed catchment whose outlet is blocked by man-made obstacles such as banks and roads, however, the water-like free drainage assumption is no longer valid because the cold air accumulates from the bottom first. We developed an empirical model to estimate quantitatively the effect of cold pool on nocturnal temperature in a closed catchment. In our model, a closed catchment is treated like a "vessel", and a digital elevation model (DEM) was used to calculate the maximum capacity of the cold pool formed in a closed catchment. We introduce a topographical variable named "shape factor", which is the ratio of the cold air accumulation potential across the whole catchment area to the maximum capacity of the cold pool to describe the relative size of temperature drop at a wider range of catchment shapes. The shape factor is then used to simulate the density profile of cold pool formed in a given catchment based on a hypsometric equation. The cold lake module was incorporated with the existing model (i.e., Chung et al., 2006), generating a new model and predicting distribution of minimum temperature over closed catchments. We applied this model to Akyang valley (i.e., a typical closed catchment of 53 $km^2$ area) in the southern skirt of Mt. Jiri National Park where 12 automated weather stations (AWS) are operational. The performance of the model was evaluated based on the feasibility of delineating the temperature pattern accurately at cold pool forming at night. Overall, the model's ability of simulating the spatial pattern of lower temperature were improved especially at the valley bottom, showing a similar pattern of the estimated temperature with that of thermal images obtained across the valley at dawn (0520 to 0600 local standard time) of 17 May 2011. Error in temperature estimation, calculated with the root mean square error using the 10 low-lying AWSs, was substantially decreased from $1.30^{\circ}C$ with the existing model to $0.71^{\circ}C$ with the new model. These results suggest the feasibility of the new method in predicting the site-specific freeze and frost warning at a closed catchment.

• Journal of the Korean Vacuum Society
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• v.17 no.3
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• pp.226-233
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• 2008

The nucleation and evolution process of Ge nano-islands on Si(001) surfaces grown by chemical vapor deposition have been explored using atomic force microscopy (AFM). The Ge nano-islands are grown by exposing the substrates to a mixture of gasses GeH4 and H2 at pressure of 0.1-0.5Torr and temperatures of $600-650^{\circ}C$. The effect of growth conditions such as temperature, Ge thickness, annealing time on the shape, size, number density, and surface distribution was investigated. For Ge deposition greater than ${\sim}5$ monolayer (ML) with a growth rate of ${\sim}0.1ML/sec$ at $600^{\circ}C$, we observed island nucleation on the surface indicating the transition from strained layer to island structure. Further deposition of Ge led to shape transition from initial pyramid and hut to dome and superdome structure. The lateral average size of the islands increased from ${\sim}20nm$ to ${\sim}310nm$ while the number density decreased from $4{\times}10^{18}$ to $5{\times}10^8cm^{-2}$ during the shape transition process. In contrast, for the samples grown at a relatively higher temperature of $650^{\circ}C$ the morphology of the islands showed that the dome shape is dominant over the pyramid shape. The further deposition of Ge led to transition from the dome to the superdome shape. The evolution of shape, size, and surface distribution is related to energy minimization of the islands and surface diffusion of Ge adatoms. In particular, we found that the initially nucleated islands did not grow through long-range interaction between whole islands on the surface but via local interaction between the neighbor islands by investigation of the inter-islands distance.

• Korean Journal of Agricultural and Forest Meteorology
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• v.3 no.4
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• pp.199-205
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• 2001

This study was conducted to figure out temperature profiles of a partially developed paddy rice canopy, which are necessary to run plant disease forecasting models. Air temperature over and within the developing rice canopy was monitored from one month after transplanting (June 29) to just before heading (August 24) in 1999 and 2001. During the study period, the temporal march of the within-canopy profile was analyzed and an empirical formula was developed for simulating the profile. A partially developed rice canopy temperature seemed to be controlled mainly by the ambient temperature above the canopy and the water temperature beneath the canopy, and to some extent by the solar altitude, resulting in alternating isothermal and inversion structures. On sunny days, air temperature at the height of maximum leafages was increased at the same rate as the ambient temperature above the canopy after sunrise. Below the height, the temperature increase was delayed until the solar noon. Air temperature near the water surface varied much less than those of the outer- and the upper-canopy, which kept increasing by the time of daily maximum temperature observed at the nearby synoptic station. After sunset, cooling rate is much less at the lower canopy, resulting in an isothermal profile at around the midnight. A fairly consistent drop in temperature at rice paddies compared with the nearby synoptic weather stations across geographic areas and time of day was found. According to this result, a cooling by 0.6 to 1.2$^{\circ}C$ is expected over paddy rice fields compared with the officially reported temperature during the summer months. An empirical equation for simulating the temperature profile was formulated from the field observations. Given the temperature estimates at 150 cm above the canopy and the maximum deviation at the lowest layer, air temperature at any height within the canopy can be predicted by this equation. As an application, temperature surfaces at several heights within rice fields were produced over the southwestern plains in Korea at a 1 km by 1km grid spacing, where rice paddies were identified by a satellite image analysis. The outer canopy temperature was prepared by a lapse rate corrected spatial interpolation of the synoptic temperature observations combined with the hourly cooling rate over the rice paddies.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.18 no.1
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• pp.63-72
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• 2020

Dissolved hexavalent uranium can exist in the form of several different chemical species. Furthermore, species distributions depend on the pH value of the aqueous solution. Representatively, UO₂²⁺, UO₂OH⁺, (UO₂)₂(OH)₂²⁺, and (UO₂)₃(OH)₅⁺ species coexist in solutions at acidic and circumneutral pH values. When amorphous silica particles are suspended in an aqueous solution, the dissolved chemical species are easily adsorbed onto silica surfaces. In this study, it was examined whether the species distribution of the adsorbed U(VI) on a silica surface followed that of the dissolved U(VI) in an aqueous solution. Time-resolved luminescence spectra of three different dissolved species (UO₂²⁺, UO₂OH⁺, and (UO₂)₃(OH)₅⁺) and two different adsorbed species (≡SiO₂UO₂, ≡SiO₂(UO₂)OH^-, or ≡SiO₂(UO₂)₃(OH)^5-) were measured in the pH range 3.5-7.5. The spectral shapes of these chemical species were compared by changing the pH value; consequently, it was confirmed that the species distribution of the adsorbed U(VI) species was different from that of the dissolved U(VI) species.

• Economic and Environmental Geology
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• v.18 no.4
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• pp.343-355
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• 1985

Spectral reflectivity and microhardness were measured quantitatively on polished surfaces of a selection of bireflecting minerals obtained from several well known metallic deposits. Incremental errors are much higher than decremental errors and errors were found to be lowest in the spectral region close to the green wavelength ($544m{\mu}$). The characteristics of the spectral profile are significant in their control of white light color. The covellite and graphite have reflectivity profiles similar in shape for each principal direction, showing noticeable difference in magnitude between the profiles: The spectral reflectivity of covellite parallel to the extraordinary vibration is higher (R$$\simeq_-$$10%) than that parallel to the ordinary vibration and graphite shows opposite feature. Reflectivity of the enargite and famatinite cut parallel to the cleavage plane is always higher (R$$\simeq_-$$5%) than that of the section cut normal. The optical symmetry of 5 bireflecting minerals was determined by noting the variation in reflectivity at $544m{\mu}$. The data indicate that covellite is optically uniaxial positive and graphite is optically uniaxial negative. The Rm values for enargite and famatinite are clearly closer to the minimum value for the mineral ($R_1$) than to the maximum value ($R_2$) : the minerals can be recognized as optically biaxial positive. Enargite and famatinite cut parallel to cleavage have much higher hardness values (HV=> $200kg/mm^2$) than those cut normal to cleavage. Vickers indentations exhibit characteristic features for all the bireflecting mineral species studied. Broad radicle groupings of the mineral species can be made with regard to the reflectivity microhardness numbers.