• Bulletin of the Korean Chemical Society
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• v.33 no.10
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• pp.3368-3372
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• 2012

The $Bi_2O_3$ nanowires are highly sensitive to low concentrations of $NO_2$ in ambient air and are almost insensitive to most other common gases. However, it still remains a challenge to enhance their sensing performance and detection limit. This study examined the influence of the encapsulation of ${\beta}-Bi_2O_3$ nanorods with $In_2O_3$ on the $NO_2$ gas sensing properties. ${\beta}-Bi_2O_3-core/In_2O_3-shell$ nanorods were fabricated by a two-step process comprising the thermal evaporation of $Bi_2O_3$ powders and sputter-deposition of $In_2O_3$. Multiple networked ${\beta}-Bi_2O_3-core/In_2O_3-shell$ nanorod sensors showed the responses of 12-156% at 1-5 ppm $NO_2$ at $300^{\circ}C$. These response values were 1.3-2.7 times larger than those of bare ${\beta}-Bi_2O_3$ nanorod sensors at 1-5 ppm $NO_2$. The enhancement in the response of ${\beta}-Bi_2O_3$ nanorods to $NO_2$ gas by the encapsulation by $In_2O_3$ can be accounted for based on the space-charge model.

• The Journal of Engineering Geology
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• v.13 no.2
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• pp.171-191
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• 2003

The objective of this present study is to understand long term(500 years) thermohydromechanical interaction behavior on joints adjacent to a repository cavern, when high level radioactive wastes are disposed of within discontinuous granitic rock masses, and then, to contribute this understanding to the development of a disposal concept. The model includes a saturated discontinuous granitic rock mass, PWR spent nuclear fuels in a disposal canister surrounded with compacted bentonite inside a deposition hole, and mixed bentonite backfilled in the rest of the space within a repository cavern. It is assumed that two joint sets exist within a model. Joint set 1 includes joints of $56^{\circ}$ dip angle, spaced 20m apart, and joint set 2 is in the perpendicular direction to joint set 1 and includes joints of $34^{\circ}$ dip angle, spaced 20m apart. The two dimensional distinct element code, UDEC is used for the analysis. To understand the joint behavior adjacent to the repository cavern, Barton-Bandis joint model is used. Effect of the decay heat from PWR spent fuels on the repository model has been analyzed, and a steady state flow algorithm is used for the hydraulic analysis.

• The Korean Journal of Petroleum Geology
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• v.9 no.1_2 s.10
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• pp.1-15
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• 2001

Hierarchically controlled sequence stratigraphic analysis shows that the Lower Ordovician mixed carbonatesiliciclastic Mungok Formation, Korea consists of three depositional sequences: T1, T2, and T3 in ascending order. Sequence boundaries are generally marked by abrupt transition from coarse-grained shallow-water carbonates to finegrained deeper-water carbonates mixed with fine-grained siliciclastics, and show indication of subaerial exposure such as karstification. Within this sequence stratigraphic framework, facies characteristics indicate that the Mungok sequences were mostly deposited on a subtidal ramp without slope break. The Mungok ramp had been under the influence of frequent tropical storm activity during deposition. The difference in lithology of tempestites seems to have been controlled by the nature of substrates and by proximality. High-frequency cycles consist of upward-shallowing facies successions. Cycles of shallow-water and basinal deposits are not well represented, probably due to cycle amalgamation. Cycle stacking patterns do not show a consistent thickness change that is usually associated with a large-scale sea-level change probably because of unfilled accommodation space.

• Journal of the Korean Vacuum Society
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• v.18 no.6
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• pp.453-458
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• 2009

SiOC film was deposited by the chemical vapor deposition using BTMSM and oxygen mixed precursor. The characteristic of SiOC film varied with increasing of the gas flow rate ratios. The dielectric constant was obtained by C-V measurement using the structure of metal/SiOC film/Si. The space effect due to the steric hindrance between alkyl group at terminal bond of Si-$CH_3$ made the pores, and increased the thickness. However, the SiOC film due to the lowering of the polarization decreased the thickness and then decreased the dielectric constant. After annealing process, the dielectric constant decreased because of the evaporation of the OH or $H_2O$ sites. The thickness was related to the lowering of the dielectric constant by the reduction of the polarization and the thickness decreased with the decrease of the dielectric constant. The refractive index was in inverse proportion to thickness. The trends of the thickness and refractive index did not change after annealing.

• The Korean Journal of Nuclear Medicine
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• v.38 no.5
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• pp.344-346
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• 2004

A 69-year-old woman was presented with progressed dysphagia, gastric soreness and weight loss during 2 months. She was performed abdomen x-ray, EGDS and abdomen CT. Abdomen x-ray demonstrated punctuate calcification on LUQ. EGDS showed an ulceroinfiltrative mass with bleeding on cardia to antrum of stomach. And CT showed diffuse gastric wall thickness with multiple calcifications. Biopsy of the stomach and esophagus during EGDS examination revealed an adenocarcinoma, with signet ring cell type, infiltrating the wall of the stomach and the distal esophagus. Then acne scan was performed a few days later. It revealed intense uptake in LUQ, corresponding to the calcium containing neoplasm seen on the abdomen x-ray, EGDS and abdomen CT. And there was no evidence of any metastatic lesion and thyroid uptake on the bone scan. There are many reports about accumulation of the tracer in extraosseous lesion, but only a few literatures were reported about gastric calcification in stomach cancer. More over, no reports showed CT images. We are performed many diagnostic examinations and found well correlation between them. The reason of gastric calcification is considered with calcium deposition within extracellular space due to hemorrhage or necrosis. Other possibility offered to explain gastric calcification have been increased blood flow and/or increased neovascularity with capillary leaks of tracer, and specific enzymatic (phosphatases) receptor binding of tracer. So, it was happened ion exchange between intracellular calcium and phosphate groups of tracer.

• Membrane and Water Treatment
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• v.11 no.1
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• pp.1-10
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• 2020

An understanding of particle-particle interactions in filtration requires studying the detachment as well as the attachment of nanoparticles. Nanoparticles captured in a granular media filter can be released by changing the physicochemical factors. In this study, the detachment of captured silver nanoparticles (AgNPs) in granular media filtration was examined under different ionic strengths, ion type, and the presence or absence of natural organic matter (NOM). Filtration velocity and ionic strength were chosen as the physical and chemical factors to cause the detachment. Increasing filtration velocity caused a negligible amount of AgNP detachment. On the other hand, lowering ionic strength showed different release amounts depending on the background ions, implying a population of loosely captured particles inside the filter bed. Overall detachment was affected by ionic strength and ion type, and to a lesser degree by NOM coating which resulted in slightly more detachment (in otherwise identical conditions) than in the absence of that coating, possibly by steric effects. The secondary energy minimum with Na ions was deeper and wider than with Ca ions, probably due to the lack of complexation with citrate and charge neutralization that would be caused by Ca ions. This result implies that the change in chemical force by reducing ionic strength of Na ions could significantly enhance the detachment compared to that caused by a change in physical force, due to a weak electrostatic deposition between nanoparticles and filter media. A modification of the 1-D filtration model to incorporate a detachment term showed good agreement with experimental data; estimating the detachment coefficients for that model suggested that the detachment rate could be similar regardless of the amount of previously captured AgNPs.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.436-437
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• 2012

Double patterning technology (DPT) has been suggested as a promising candidates of the next generation lithography technology in FLASH and DRAM manufacturing in sub-40nm technology node. DPT enables to overcome the physical limitation of optical lithography, and it is expected to be continued as long as e-beam lithography takes place in manufacturing. Several different processes for DPT are currently available in practice, and they are litho-litho-etch (LLE), litho-etch-litho-etch (LELE), litho-freeze-litho-etch (LFLE), and self-aligned double patterning (SADP) [1]. The self-aligned approach is regarded as more suitable for mass production, but it requires precise control of sidewall space etch profile for the exact definition of hard mask layer. In this paper, we propose etch end point detection (EPD) in spacer etching to precisely control sidewall profile in SADP. Conventional etch EPD notify the end point after or on-set of a layer being etched is removed, but the EPD in spacer etch should land-off exactly after surface removal while the spacer is still remained. Precise control of real-time in-situ EPD may help to control the size of spacer to realize desired pattern geometry. To demonstrate the capability of spacer-etch EPD, we fabricated metal line structure on silicon dioxide layer and spacer deposition layer with silicon nitride. While blanket etch of the spacer layer takes place in inductively coupled plasma-reactive ion etching (ICP-RIE), in-situ monitoring of plasma chemistry is performed using optical emission spectroscopy (OES), and the acquired data is stored in a local computer. Through offline analysis of the acquired OES data with respect to etch gas and by-product chemistry, a representative EPD time traces signal is derived. We found that the SE-EPD is useful for precise control of spacer etching in DPT, and we are continuously developing real-time SE-EPD methodology employing cumulative sum (CUSUM) control chart [2].

• The Journal of Engineering Geology
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• v.11 no.3
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• pp.255-267
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• 2001

A comparison study is performed to understand the coupling behavior of the thermal, hydraulic, and mechanical interactions in the vicinity of an underground radwaste repository, assumed to be located at a depth of 500 m, within a granitic rock mass with a 58$^{\circ}$ dipping fault passing through the roof-wall intersection of the repository cavern. The two dimensional universal distinct element code, UDEC is used for the analysis. The model includes a granitic rock meas, a canister with PWR spent fuels surrounded by the compacted bentonite inside a deposition hole, and the mixed bentonite backfilled in the rest of the space within a repository cavern. The coupling behavior of hydromechanical, thermomechanical, and thermohydromechanical interaction has been studied and compared. The effect of the time-dependent decaying heat, from the radioactive materials in PWR spent fuels, on the repository and its surroundings has been studied. A steady state flow algorithm is used for the hydraulic analysis.

• Journal of the korean academy of Pediatric Dentistry
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• v.2 no.1
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• pp.67-75
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• 1975

The conserative treatment of the necrotic and infected primary molars is often necessary in order to avoid extractions which may lead to inability to masticate or loss of space and subsequent problems concerning the development of the occlusion in the permanent dentition. The purpose of this study was to evaluate the clinical significance of the conservative treatment of the infected primary molars with necrotic pulps employing the formocresol pulpotomy technique same as in vital teeth and surgical intervention in the cases with a parulis, fistula or cellulitis. The materials consisted of 25 primary molars of 9 boys and 4 girls ranging in age from 4 to 7 years. This study included clinical and radiographic observation at 3-month intervals postoperatively. The following results were obtained. 1. Clinically, 20 cases of 25 were successful, exhibiting no clinical problems such as fistula, mobility, toothache and tenderness to percussion, etc. 5 cases were regarded as failures. 2. Radiographiclly, 14 cases revealed normal features, in 6 cases slight rarefaction was observed in the periapical and interradicular region, and marked periapical and interradicular rarefaction was observed in 5 cases. 3. Marked bony deposition was observed in the periapical and interradicular regions in all the remainder except for 5 failurese. 4. Pathologic root resorption was observed in 2 cases. 5. No alveolodental ankylosis was observed. 6. Regeneration of the dental sac of the permanent tooth was observed in 1 case of 2 cases which had revealed loss of the dental sac.

• Membrane Journal
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• v.21 no.4
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• pp.351-359
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• 2011

For advanced drinking water treatment of high turbidity water, we used the hybrid process that was composed of photocatalyst packing in space of between outside of multi-channel ceramic microfiltration membrane and membrane module inside. Photocatalyst was polypropylene (PP) beads coated $TiO_2$ powder by CVD (chemical vapor deposition) process. Instead of natural organic matters (NOM) and fine inorganic particles in natural water source, standard NOM solution was prepared with humic acid and kaolin. Water-back-flushing of 10 sec was performed per every period of 10 min to minimize membrane fouling. Resistance of membrane fouling ($R_f$) increased and J decreased as concentration of humic acid changed from 2 mg/L to 10 mg/L, and finally the highest total permeate volume ($V_T$) could be obtained at 2 mg/L. Then, treatment efficiency of turbidity and $UV_{254}$ absorbance were above 96.4% and 78.9%, respectively. As results of treatment portions by membrane filtration, photocatalyst adsorption, and photo-oxidation in (MF), (MF + $TiO_2$), (MF + $TiO_2$ + UV) processes, turbidity was treated little by photocatalyst adsorption, and photo-oxidation. However, treatment portions of $UV_{254}$ absorbance by adsorption (MF + $TiO_2$) and photo-oxidation (MF + $TiO_2$ + UV) at humic acid of 4 mg/L and 6 mg/L were above 9.0, 9.5 and 8.1, 10.9%, respectively.