• The Journal of the Petrological Society of Korea
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• v.16 no.3
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• pp.116-128
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• 2007

Detailed geological mapping, petrographic study, analyses of geochemistry and magnetic susceptibility, and K-Ar dating were carried out in order to determine the origin, age, and stratigraphic implications of granitic rock fragments in the pyroclastic rocks, SE Jinhae city, southern part of the Gyeongsang Basin. As a result, it was found that the area is composed of volcanics and tuffaceous sediments of the Yucheon Group, Bulguksa granites, pyroclastics bearing granitic rock fragments, $basalt{\sim}basaltic$ andesite, and rhyolite in ascending stratigraphic order. The granitic rock fragments in the pyroclastic rocks are divided into granodiorite and biotite granite, which have approximately the same characteristics as the granodiorite and the biotite granite of the Bulguksa granites, respectively, in and around the study area including color, grain size, mineral composition, texture (perthitic and micrographic textures), intensity of magnetic susceptibility (magnetite series), and geochemical features (calc-alkaline series and REE pattern). This leads to the conclusion that the rock fragments originated from the late Cretaceous Bulguksa granites abundantly distributed in and around the study area, but not from the basement rocks of the Yeongnam massif or the Jurassic granites. Based on relative and absolute ages of various rocks in the study area, the pyroclastics bearing granitic rock fragments are interpreted to have erupted between 52 and 16 Ma, i.e. during the Eocene and early Miocene. These results indicate that the various volcanisms, acidic to basic in composition, occurred after the intrusion of the Bulguksa granites, contrary to the general stratigraphy of the Gyeongsang Basin. Very detailed and cautious mapping together with relative and absolute age determinations are, thus, necessary in order to establish reliable stratigraphy of the Yucheon Group in other areas of the Gyeongsang Basin.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.4
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• pp.388-395
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• 2016

This paper explores the photocatalytic sensitivity of cement mortar incorporated with recycled $TiO_2$ from waste water sludge. Basically, $TiO_2$ cluster sank down slowly to the bottom of cement mortar specimen before setting and hardening process. This leads the mismatch of $TiO_2$ concentration on the top and the bottom faces of a specimen. This poorly dispersed $TiO_2$-cement mortar naturally exhibits poor NOx removal efficiency especially on the top of cementitious structure. In architectural engineering application such as building or housing structures, one can simply filp over from the bottom so that more $TiO_2$ concentrated surface can be placed outward into the air. However, in highway pavement case, this could not be applicable due to in-situ installation of concrete pavement. Hence, the dispersion of $TiO_2$ cluster inside the cementitous material is getting important issue onto road construction application. To elaborate this issue, according to our results, silica fume, high-ranged water reducer, viscosity agent, blast furnace slag were not enhanced much of dispersion characteristics of $TiO_2$ cluster. The combination of foaming agent and accelerator of hardening with viscosity agent and small grain size of fine aggregate may help the dispersion of $TiO_2$ inside cementitious materials. Even though the enhanced dispersion were applied to the specimen, NOx removal efficiency doest not change much for the top surface of the specimen. This concurrently affected by the presence of tiny air voids and the dispersion of $TiO_2$ in that these voids could easily adsorbed NOx gas with the aid of large surface area.

• Journal of Bio-Environment Control
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• v.7 no.4
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• pp.298-310
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• 1998

This research was carried out to find out spray characteristics of 3 types of spray nozzle to be used for greenhouse cooling. Following results were obtained from this experimental study. Water amounts sprayed with each nozzle were increased with the spraying pressure. However the increment of sprayed amount with the increase of spraying pressure were not consistent regardless of nozzle types. For the whole tested spraying pressures of nozzle-type I, II, III, the minimum droplet sizes were about 1.7~2.5$\mu$m, 1.7~2.2$\mu$m and 1.7~2.2$\mu$m, respectively, and the maximum droplet sizes were about 44~60$\mu$m, 52~71$\mu$m and 45~61$\mu$m, respectively, and the average droplet sizes were about 23~38$\mu$m, 19~24$\mu$m and 17~25$\mu$m, respectively The most appropriate spraying pressures of nozzle-type I, II, III were analyzed to be 70kgf/$\textrm{cm}^2$, 30kgf/$\textrm{cm}^2$ and 30kgf/$\textrm{cm}^2$, respectively, and their sprayed amounts were about 124mL/min, 103mL/min and 84mL/min, respectively, and average droplet sizes were 22.6$\mu$m, 21.8$\mu$m and 20.6$\mu$m, respectively. Also, with the order of nozzle-type I, II, III, droplet size distributions less than 30$\mu$m were 95.4%, 85.7% and 79.0%, respectively, and the distributions larger than 40$\mu$m were 0.2%, 1.28% and 1.67%, respectively. However most all of the droplet size were less than 50$\mu$m.

• 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 $2.15%{\sim}2.42%$.

• Restorative Dentistry and Endodontics
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• v.32 no.6
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• pp.498-513
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• 2007

Since it was reported that incipient enamel caries can be recovered, previous studies have quantitatively evaluated that enamel artificial caries have been, remineralized with fluoride showing simultaneously the increase of width of surface layer and the decrease of width of the body of legion. There is, however, little report which showed that remineralization could occur without fluoride. In addition, the observations on the change of hydroxyapatite crystals also have been scarcely seen. In this study, enamel caries in intact premolars or molars was induced by using lactic acidulated buffering solutions over 2 days. Then decalcified specimens were remineralized by seven groups of solutions using different degree of saturation(0.212, 0.239, 0.301, 0.355) and different pH(5.0, 5.5, 6.0) over 10 days. A qualitative comparison to changes of hydroxyapatite crystals after fracturing teeth was made under SEM(scanning electron microscopy) and AFM(atomic force microscopy). The results were as follows: 1. The size of hydroxyapatite crystals in demineralized area was smaller than the normal ones. While the space among crystals was expanded, it was observed that crystals are arranged irregularly. 2. In remineralized enamel area, the enlarged crystals with various shape were observed when the crystals were fused and new small crystals in intercrystalline spaces were deposited. 3. Group 3 and 4 with higher degree of saturation at same pH showed the formation of large clusters by aggregation of small crystals from the surface layer to the lesion body than group 1 and 2 with relatively low degree of saturation at same pH did. Especially group 4 showed complete remineralization to the body of lesions. Group 5 and 6 with lower pH at similar degree of saturation showed remineralization to the body of lesions while group 7 didn't show it. Unlike in Group 3 and 4, Group 5 and 6 showed that each particle was densely distributed with clear appearance rather than crystals form clusters together.

• Journal of the Korean Electrochemical Society
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• v.10 no.4
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• pp.239-244
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• 2007

In order to investigate the effect of fluorine ion in the $Li_{1-x}FeO_2Li_xMnO_2$ (Mn/(Mn + Fe) = 0.8) cathode material, it was synthesized $Li_{1-x}FeO_{2-y}F_y-Li_xMnO_2$ (Mn/(Mn + Fe) = 0.8, $0.05{\le}y{\le}0.15$) cathode materials at $350^{\circ}C$ for 10hrs using solid-state method. $Li_{1-x}FeO_{2-y}F_y-Li_xMnO_2$ (Mn/(Mn + Fe) = 0.8, $0.0{\le}y{\le}0.1$ was composed many large needle-like particles of about $1-1.5\;{\mu}m$ and small particles of about 50-100 nm, which were distributed among the larger particles. However, $Li_{1-x}FeO_{1.85}F_{0.15}-Li_xMnO_2$ material showed slightly different particle morphology. The particles of $Li_{1-x}FeO_{1.85}F_{0.15}-Li_xMnO_2$ were suddenly increased and started to be a spherical type of particle shape. $Li/Li_{1-x}FeO_{1.9}F_{0.1}-Li_xMnO_2$ cell showed a high initial discharge capacity of 163 mAh/g and a high cycle retention rate of 95% after 50 cycles. The initial discharge capacity of $Li/Li_{1-x}FeO_{2-y}F_y-Li_xMnO_2$ ($0.05{\le}y{\le}0.15$) cells increased according to the increase of F content. However, the cycleability of this cell was very rapidly decreased when the substituted fluorine content is over 0.1. We suggested that too large amount of F ion fail to substitute into the $Li_{1-x}FeO_2-Li_xMnO_2$ structure, which resulted in the severe decline of battery performance.

• Economic and Environmental Geology
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• v.41 no.4
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• pp.405-425
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• 2008

In order to investigate the amounts of trace elements flowing into reservoir, and to elucidate the relationship between trace element mobility and fraction size, the stream water and sediment samples were collected from thirty-two sites of the 3rd or 4th order stream within watershed surrounding the Juam reservoir. Chemical analyses of trace elements (As, Cd, Cr, Cu, Ni, Pb and Zn) for all samples were completed, and additionally cationi and anion for stream water samples. Considering the distribution of rocks and contamination sources in watershed, the eight stream sediments were selected from typical sites representing study areas, and we determined the concentrations of trace elements according to size fractions ($2\;mm{\sim}200\;{\mu}m$, $200{\sim}100\;{\mu}m$, $100{\sim}50\;{\mu}m$, $50{\sim}20\;{\mu}m$ and < $20\;{\mu}m$). The correlation relationships between concentrations and size fractions of stream sediments were important to identify the hydro-geochemical behavior of trace elements that flow into Juam reservoir. Stream waters showed four water types (Ca-Mg-$HCO_3$, Ca-Na-$HCO_3$-Cl, Ca-Na-$HCO_3-SO_4$, Ca-Na-$HCO_3$) depending on pollution sources such as coal mine, metal mine, farm-land and dwellings. Concentrations of trace elements increased clearly with the decrease in size fractions of stream sediments. Concentrations of Cu, Pb and Zn increased dramatically in silt size (< $20\;{\mu}m$) fraction, while As had high concentrations in sand size ($2\;mm{\sim}100\;{\mu}m$) fraction in downstream sediments of metal mines. These indicate that Cu, Zn, and Pb moved into Juam reservoir easily in the adsorbed form on silt size grain in sediments, and As was transported as As-bearing mineral facies, resulting in its less chance to reach into Juam reservoir.

• Journal of Soil and Groundwater Environment
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• v.10 no.6
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• pp.20-31
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• 2005

Three dimensional Monte-Carlo simulations of non-ergodic transport of a lion-reactive solute plume by steady-state groundwater flow under a uniform mean velocity in isotropic heterogeneous aquifers were conducted. The log-normally distributed hydraulic conductivity, K(x), is modeled as a random field. Significant efforts are made to reduce tile simulation uncertainties. Ensemble averages of the second spatial moments of the plume and plume centroid variances were simulated with 1600 Monte Carlo runs for three variances of log K, ${\sigma}_Y^2=0.09,\;0.23$, and 0.46, and three dimensionless lengths of line plume sources normal to the mean velocity. The simulated second spatial moment and the plume centroid variance in longitudinal direction fit well to the first order theoretical results while the simulated transverse moments are generally larger than the first order results. The first order theoretical results significantly underestimated the simulated dimensionless transverse moments for the aquifers of large ${\sigma}_Y^2$ and large dimensionless time. The ergodic condition for the second spatial moments is far from reaching in all cases simulated, and transport In transverse directions may reach ergodic condition much slower than that in longitudinal direction. The evolution of the contaminant transported in a heterogeneous aquifer is not affected by the shape of the initial plume but affected mainly by the degree of the heterogeneity and the size of the initial plume.

• Journal of the Korean Magnetics Society
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• v.15 no.1
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• pp.42-47
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• 2005

Nanocrystalline Nd-Fe-B powder was synthesized by a new thermochemical process that combined with past reduction-diffusion process and spray-dry process. In this process, Ca reduction process is vary important due to formation of hard magnetic$Nd_{2}Fe_{14}B$ phase from various oxides by Ca powder. Therefore, the final products are essentially affected a shape, size, and composition etc. of the Ca reduced powders. Ca reduction was performed to way that raw powders just mixed with Ca powder in proper ratio unlike to compress into compact. The powders after mixture-type Ca reduction mainly composited with $Nd_{2}Fe_{14}B$ phase even relativily low reaction temperature ($800^{\circ}C$) and all particle size of powder were distributed less than 1 ${\mu}m$ except for powder after Ca oxides as magnetic properties of powders after cake-type Ca reduction, with the consequence that high magnetic properties has been expected. The magnetic properties of powders prepared by mixture-type Ca ruduction, with the conseqence that high magnatic properties has been expected. The magnetic properties of powders prepared by mixture-type Ca reduction process showed $_iH_c$ = 5.9 kOe, $B_r$ = 5.5 kG, (BH)max = $Nd_{2}Fe_{14}B{\to}Nd_{2}Fe_{17}B$ decomposition by violent exothermic reaction during washing.

• Korean Journal of Materials Research
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• v.6 no.7
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• pp.700-708
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• 1996

Electroless plating technique was utilized to flip chip bonding to improve surface mount characteristics. Each step of plating procedure was studied in terms pf pH, plating temperature and plating time. Al patterned 4 inch Si wafers were used as substrstes and zincate was used as an activation solution. Heat treatment was carried out for all the specimens in the temperature range from room temperature to $400^{\circ}C$ for $30^{\circ}C$ minutes in a vacuum furnace. Homogeneous distribution of Zn particles of size was obtained by the zincate treatment with pH 13 ~ 13.5, solution concentration of 15 ~ 25% at room temperature. The plating rates for both Ni-P and Au electroless plating steps increased with increasing the plating temperature and pH. The main crystallization planes of the plated Au were found to be (111) a pH 7 and (200) and (111) at pH 9 independent of the annealing temperature.