• JSTS:Journal of Semiconductor Technology and Science
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• v.3 no.3
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• pp.132-138
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• 2003

We investigated the polarization retention characteristics of ferroelectric capacitors with $Pb(Zr,Ti)O_3$ (PZT) thin films which were fabricated by different deposition methods. In thermally-accelerated retention tests, PZT films which were prepared by a chemical solution deposition (CSD) method showed rapid decay of retained polarization charges as the thickness of the films decreased down to 100 nm, while the films which were grown by metal organic chemical vapor deposition (MOCVD) retained relatively large non-volatile charges at the corresponding thickness. We concluded that in the CSD-grown films, the thicker interfacial passive layer compared with the MOCVD-grown films had an unfavorable effect on retention behavior. We observed the existence of such interfacial layers by extrapolation of the total capacitance with thickness of the films and the capacitance of these layers was larger in MOCVD-grown films than in CSD-grown films. Due to incomplete compensation of surface polarization charges by the free charges in the metal electrodes, the interfacial field activated the space charges inside the interfacial layers and deposited them at the boundary between the ferroelectric layer and the interfacial layer. Such space charges built up an internal field inside the films, which interfered with domain wall motion, so that retention property at last became degraded. We observed less imprint which was a result of less internal field in MOCVD-grown films while large imprint was observed in CSD-grown films.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.45 no.6
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• pp.88-95
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• 2013

Effects of beating and water immersion time on fiber swelling and paper properties were elucidated for the fundamental study of producing high bulk paper. Chemical pulps were beaten for various freeness and the beaten pulp was immersed in water up to 24 hours. Fiber swelling was evaluated by measuring water retention value (WRV). It was found that fiber swelling, bulk and paper strength were quickly changed at the initial stage of beating. Immersion in water did not significantly increase WRV, paper density and strength, implying that soaking in water alone could not effectively swell fiber wall. In order to swell further, hydrogen bonds between fibrils in fiber wall and hence fiber wall structure shall be broken by mechanical force during beating.

• Journal of the Korean Wood Science and Technology
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• v.27 no.3
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• pp.7-16
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• 1999

This research was carried out to compare structure, equilibrium moisture content(EMC), adsorption and acoustical properties between 4 retention levels of saligenin(o-hydroxybenzyl alcohol) treated, heat-treated and untreated chestnut(Castanea crenata S. et Z.) and paulownia(Paulownia spp.) woods. The cell structures of untreated wood and heat-treated wood were not different but the cell wall of saligenin treated wood was thicker than that of untreated wood for both species. EMC of untreated wood was the highest, next was that of heat-treated wood, and that of saligenin treated wood was the lowest, and among saligenin treated woods, EMC was decreased as retention level increased for both species. Adsorption curves were parabolically increased. Acoustical properties of saligenin treated wood were most improved, and the next were those of heat-treated wood. Comprehensive acoustical property was improved at retention level 20% and 30% for chestnut wood, and at retention level 80% for paulownia wood.

• Journal of the Korean Society of Clothing and Textiles
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• v.21 no.7
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• pp.1196-1204
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• 1997

Cotton, rayon/cotton, and Tencel twill weave fabrics were used to investigate the effect of fiber types on the cellulase washing finish. And twill. basket, and derivative weave cotton fabrics were used to study the weave effect. Various fabrics were treated with neutral cellulase varying treatment times and with acid cellulase, stone, and stone-neutral cellulase respectively for two hours in a rotary washer. Weight loss decreased in the order of rayon/cotton> cotton> Tencel, and basket and derivative weave fabrics lost more weight than twill weave fabric. Color difference decreased in the order of cotton> Tencel> rayon/cotton, and twill weave fabric had larger color difference than derivative and basket weave fabrics. Back staining decreased in the order of cotton> rayon/cotton> Tencel, and twill weave fabric had larger back staining than derivative and basket weave fabrics. Tear strength retention decreased in the order of rayon/cotton> cotton> Tencet and twill weave fabric had larger tear strength retention than derivative and basket weave fabrics. Flex stiffness retention decreased in the order of cotton> Tencel> rayon/cotton, and in the order of derivative> twill> basket weave. In cotton fibers, damage of primary wall was observed. And the cellulase treatment on Tencel seemed to roughen the fabric surface slightly, and to fibril fibers along the fiber axis.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.10a
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• pp.713-718
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• 1997

In the TMI-2 accident, approximately twenty(20) tons of molten core material drained into the lower plenum. Early advanced light water reactor (LWR) designs assumed a lower head failure and incorporated various measures for ex-vessel accident mitigation. However, one of the major findings from the TMI-2 Vessel Investigation Project was that one part of the reactor lower head wall estimated to have attained a temperature of 1100$^{\circ}C$ for about 30 minutes has seemingly experienced a comparatively rapid cooldown with no major threat to the vessel integrity. In this regard, recent empirical and analytical studies have shifted interests to such in-vessel retention designs or strategies as reactor cavity flooding, in-vessel flooding and engineered gap cooling of the vessel Accurate thermohydrodynamic and creep deformation modeling and rupture prediction are the key to the success in developing practically useful in-vessel accident/risk management strategies. As an advanced in-vessel design concept, this work presents the COrium Attack Syndrome Immunization Structures (COASIS) that are being developed as prospective in-vessel retention devices for a next-generation LWR in concert with existing ex-vessel management measures. Both the engineered gap structures in-vessel (COASISI) and ex-vessel (COASISO) are demonstrated to maintain effective heat transfer geometry during molten core debris attack when applied to the Korean Standard Nuclear Power Plant(KSNPP) reactor. The likelihood of lower head creep rupture during a severe accident is found to be significantly suppressed by the COASIS options.

• The Journal of Korean Academy of Prosthodontics
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• v.30 no.3
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• pp.437-443
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• 1992

This study was performed to investigate the availability of adhesive resin cement for luting agent of cast crown. The resin cements used in this study were Panavia-Ex(Kuraray Co., Japan) and C & B-Metabond (Parkell Bio-Materials U.S.A.). Zinc phosphate cement was Flecks zinc cement(Mizzy Inc., U.S.A.) The film thickness of cast crown at gingival margin, lateral wall and occlusal surface was observed with measuring microscope(Modek MXT 70 Matsuzawa Seiki Co., Japan) and the retention of cast crown was measured with Instron Universal Test Machine (Instron Engineering Co., U.S.A.) The results were as follows : 1. The value of retention of cast crown was the highest in the use of Panavia-EX, followed by C & B-Metabond and 2inc phosphate cement, respectively. 2. There was no difference in film thickness among the three cements, but the film thickness in all cements was highest at occlusal surface.

• Geotechnical Engineering
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• v.9 no.1
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• pp.59-68
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• 1993

In deep excavations for creation of underground spaces, it would be difficult to predict earth pressure, especially multilayered ground including rock strata. The earth pressures and displacements on the retention walls are measured by load cell, strain gauge and inclinometer which were installed at struts or anchors at 4 deep excavation sites in Seoul area. In this paper, the measured earth pressure from the struts or anchors are compared with Peck's empirical values, and the coefficient of the earth pressures for each strata and horizontal wall displacement are investigated. The coefficient of earth pressure distribution, a(0.65zka), in the flexible and the rigid walls was about 74% and 88% of Peck's value respecitively. The measured earth pressure distributions for the 4 sites showed about 70%∼80% of Peck's empirical values and the average earth pressure coefficients based on the measured data were 0.3 for the felted layer, 0.23 for the weathered rock and 0.19 for the weak rock. The maximum w리1 displacements were found to be less 0.2% of excavation depth.

• Physical Therapy Rehabilitation Science
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• v.7 no.3
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• pp.95-101
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• 2018

Objective: To determine if the provision of visual biofeedback using real-time rehabilitative ultrasound imaging (RUSI) enhances the acquisition and retention of diaphragm muscle recruitment during exercise. Design: Two group pretest posttest design. Methods: Thirty healthy subjects were randomly assigned to the verbal feedback group (VG, n=15) or the visual and verbal feedback group (VVG, n=15). The VG performed breathing exercises 10 times with verbal feedback, and the VVG also performed breathing exercises 10 times with verbal feedback and visual feedback with the use of RUSI to measure changes in diaphragm thickness (DT). For DT, the mid-axillary lines between ribs 8 and 9 on both sides were measured in standing, and then the chest wall was perpendicularly illuminated using a linear transducer with the patients in supine to observe the region between rib 8 and 9 and to obtain 2-dimensional images. DT was measured as the distance between the two parallel lines that appeared bright in the middle of the pleura and the peritoneum. After one week, three repetitions (follow-up session) were performed to confirm retention effects. Intra- and between- group percent changes in diaphragm muscle thickness were assessed. Results: In the VVG, the intervention value had a medium effect size compared to the baseline value, but the follow-up value decreased to a small effect size. In the between-group comparisons, during the intervention session, the VVG showed no significant effect on percent change of DT but had a medium effect size compared to the VG (p=0.050, Cohen's d=0.764). During the follow-up session, retention effect did not persist (p=0.311, Cohen's d=0.381). Conclusions: RUSI can be used to provide visual biofeedback and improve performance and retention in the ability to activate the diaphragm muscle in healthy subjects. Future research needs to establish a protocol for respiratory intervention to maintain the effect of diaphragmatic breathing training using RUSI with visual feedback.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1666-1672
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• 2008

In this study, it collected and analyzed a construction case of the improved top-down support system application field on a case by case retaining wall method. The behavior of horizontal displacement was analyzed according to retaining wall type after reviewing a design stage and estimated horizontal displacement under the construction. The study results showed that it is judged stable until excavation termination irrelevant to a retaining wall method at the improved top-down support system application. It is judged that the settlement of behind ground can minimize because the retaining wall head displacement also behave stably. It was compared the predicted horizontal displacement in design and the measured horizontal displacement acquired through a measurement by using Elasto-Plastic analysis program. The comparison results showed that a similar horizontal displacement was predicted within stability standard irrelevant to a retaining wall method. So, it is decided that the advanced prediction is reasonable by Elasto-Plastic analysis in design applied the improved top-down support system. In the case of the ground anchor method application under a same condition, it is decided that a horizontal displacement will more increase than the improved top-down support system is applied. If a section condition is same, it was decided that to apply top-down support system is more stable than that.

• Korean Journal of Food Science and Technology
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• v.31 no.6
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• pp.1563-1569
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• 1999

For the encapsulation of flavor compounds, maltodextrin (MD), gum arabic (GA) alkenylsuccinated modified starch (MS) and gellan gum were chosen for wall materials and their combination was optimized. Five fruit flavor compounds having boiling point of $90{\sim}200^{\circ}C$ were selected as core materials and their mixture was incorporated with rapeseed oil (flavor mixture to oil = 1 : 4). Flavor compound mixture to wall material ratio of 1 : 4 was selected, and the amount of maltodextrin was fixed to 30% of the wall material mixture. Gellan gum was selected as an additional wall material to increase emulsion stability. The optimum combination ratio of the wall material mixture for maximal total oil retention and minimal surface oil content is : 30.0% MD ; 26.4% GA ; 39.6% MS ; 4% gellan gum.