• Elastomers and Composites
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• v.49 no.1
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• pp.43-52
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• 2014

The effect of nanoclay (Cloisite 20A) on the self-adhesion behavior of uncured brominated-isobutylene-isoprene rubber (BIIR) has been studied. The dispersion state of nanoclay into the rubber matrix was examined by SEM, TEM and XRD analysis. The thermal degradation behavior of the filled and unfilled samples was examined by TGA and improvement in the thermal stability of the nanocomposites occurred based on the weight loss (%) measurements. Also, addition of nanoclay enhanced the cohesive strength of the material by reinforcement action thereby reducing the degree of molecular diffusion across the interface of butyl rubber. However, the average depth of penetration of the inter-diffused chains was still adequate to form entanglement on either side of the interface, and thus offered greater resistance to peeling, resulting in high tack strength measurements. The improvement in tack strength was only achieved at critical nanoclay loading above 8 phr. Contact angle measurement was also made to examine the surface characteristics. There was no significant interfacial property change by employing the nanoclay.

• Conservation Science in Museum
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• v.17
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• pp.101-116
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• 2016

Ceramic cultural artifacts restored with gypsum-based materials are prone to decay over time due to gypsum's natural absorption and release of atmospheric moisture, often leading to distortion and peeling of painted layers. This study proposes a new restoration material which utilizes extra hard stone, significantly superior in strength to regular gypsum. In order to enhance its physical properties and make it suitable for restoration of ceramics, extra hard stone is mixed with metakaolin. This mixture far surpasses regular gypsum in compressive strength(119MPa vs. 26MPa) while also maintaining a much lower wear rate(0.88% vs. 2.53%). Furthermore, the water absorption rate(2.9%) of the mixed material is over five times lower than that of regular gypsum(17.2%). When examined using a SEM(Scanning Electron Microscope), this mixture also proved superior to extra hard stone in terms of hardened density. The addition of metakaolin increases the mixture's strength and water resistance over that of extra hard stone and also improves its surface density, making it ideal for the restoration of ceramics. It has already been used to repair ceramic objects in the Museum's collection: Clay basin(sinan 18892), Buncheong ware bottle with incised peony design(jubsu 2034), Buncheong ware bowl with chrysanthemum(jubsu 1730). Results thus far have shown the mixture to be easy to inject and layer as well as harden into an even surface, which allows for smooth application of paint for color matching.

• Journal of the Korean Ceramic Society
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• v.44 no.12
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• pp.740-746
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• 2007

The potential candidates for IT-SOFCs cathode materials, $Ba_{0.5}Sr_{0.5}Co_{0.8}Fe_{0.2}O_{3-{\delta}}$ (BSCF) and $La_{0.6}Ba_{0.4}Co_{0.2}Fe_{0.8}O_{3-{\delta}}$ (LBCF) powders, were synthesized by a EDTA-citrate combined method from $Sr(NO_3)_2$, $Ba(NO_3)_2$, $La(NO_3)_3{\cdot}6H_2O$, $Co(NO_3)_2{\cdot}6H_2O$, $Fe(NO_3)_3{\cdot}9H_2O$, citric acid and $EDTA-NH_3$. The cathode performance of symmetrical electrochemical cells consisting of BSCF-GDC or LBCF-GDC composite electrodes and a GDC electrolyte was investigated using by AC impedance spectroscopy at the temperature range of 500 to $700^{\circ}C$. It was found that a single phase perovskite could be successfully synthesized when the precursor is heated at $850^{\circ}C$ for 2 h. Due to thermal expansion mismatch between BSCF and GDC, the composite cathodes with lower GDC content than 45 wt% were peeled off from the GDC electrolyte and their electrode polarization resistance was estimated to be high. The thermal expansion coefficient of BSCF-GDC composites was decreased with increasing the GDC content and the electrode peeling off did not occur in BSCF-45 and 55 wt% GDC composites. BSCF-45 wt% GDC composite electrode showed the lowest area specific resistances (ASR) of 0.15 and $0.04{\Omega}{\cdot}cm^2$ at 600 and $700^{\circ}C$, respectively. On the other hand, LBCF-GDC composite cathodes showed higher ASR than the BSCF-45 and 55 wt% GDC and their cathode performance were decreased with the GDC content.

• Journal of Technologic Dentistry
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• v.34 no.2
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• pp.95-103
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• 2012

Purpose: Fracture strength of all-ceramic 3-unit fixed partial dentures manufactured by CAD/CAM and copy-milling systems were evaluated. Methods: Zirconia cores were made by milling the pre-sintered zirconia block by CAD/CAM or copy milling method followed by subsequent sintering. By building-up the corresponding porcelains on the core, all-ceramic bridges were fabricated, and those were evaluated in comparison with PFM fixed partial denture. Results: During the flexural test of the 3-unit PFM bridge, the porcelain started to chip or break at 507.28(${\pm}62.82$)kgf and the metal framework did not break until the maximum load level of 800kgf which was set in the testing instrument of this study. However, among all-ceramic restoration test groups, Everest(EV) group showed a peeling off or breakage of the porcelain from 365.64(${\pm}64.96$)kgf and the core was broken at 491.77(${\pm}55.62$)kgf. Those values of Zirkonzahn(ZR) were 431.03(${\pm}58.47$)kgf and 602.74(${\pm}48.44$)kgf, respectively. The break strength of the porcelain of PFM(PM) group was significantly higher than that of EV (p<0.05) group and there was no significant difference when comparing to that of ZR (p>0.05). ZR group showed higher break strength than that of EV group however there was no significant difference (p>0.05). The break strength of cores were in the increasing order of EV < ZR < PM (p<0.05). Conclusion: We could find that even though the PM group fractured at much higher value than all-ceramic cores, the breakage values of the porcelain of PM group with crack formation or delamination, which will be regarded as clinical failure, was significantly higher than that of EV group and not significantly higher than that of ZR group at p-values of 0.05. The break strength of ZR group was higher than that of EV group at an insignificant level(p>0.05).

• Korean Journal of Food Science and Technology
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• v.38 no.4
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• pp.526-533
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• 2006

This study was carried out to investigate the efficacy of strong acidic electrolyzed acid water (SAEW; Strong acidic electrolyzed water, pH 2.76, ORP 1,128 mV, HClO 105.0 ppm) and low alkaline electrolyzed water (LAEW; Low alkaline electrolyzed water, pH 8.56, ORP 660 mV, HClO 73.8 ppm) as storing liquid for peeled lotus root. During storage at $5^{\circ}C$, it was showed that SAEW and LAEW inhibit growth of microorganisms until at least 5 days of storage. Total phenolic contents, polyphenol oxidase (PPO) activity, and color differences value $({\Delta}E)$ of peeled lotus roots stored in SAEW and LAEW were lower than that of one stored in TW (tap water). The hardness decrement of lotus roots stored in SAEW and LAEW were lower than that of lotus root stored in TW too. Contents of moisture crude protein crude fat, crude ash, crude fiber, and total sugars were gradually decreased during storage. Whereas vitamin C content of lotus root stored in 0.6% acetic acid was most rapidly decreased to 25% as compared with one of initial days of storage that of lotus roots stored in SAEW and LAEW was not decreased significantly as compared with one stored in TW. Sensory characteristic during storage was preferable on lotus root stored in SAEW to the other treatments.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.12
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• pp.37-42
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• 1999

In this paper, some of main processes for the next generation integrated circuits, such as Cu damascene process using CMP, electron beam lithography, $SiO_2$ CVD and RIE, Ti/Cu-CVD were carried cut and then, two level Cu interconnects were accomplished. In the results of CMP unit processes, a 4,635 ${\AA}$/min of removal rate, a selectivity of Cu : $SiO_2$ of 150:1, a uniformity of 4.0% are obtained under process conditions of a head pressure of 4 PSI, table and head speed of 25rpm, a oscillation distance of 40 mm, and a slurry flow rate of 40 ml/min. Also 0.18 ${\mu}m\;SiO_2$ via-line patterns are fabricated using 1000 ${\mu}C/cm^2$ dose, 6 minute and 30 second development time and 1 minute and 30 second etching time. And finally sub-0.2 ${\mu}$ twolevel metal interconnects using the developed processes were fabricated and the problems of multilevel interconnects are discussed.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.5
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• pp.622-628
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• 2007

Most fresh-cut agri-food products are less stable than unprocessed materials from which they are made. The objective of this study was the development of a quality control system for fresh-cut agri-food products. In this study, vitamin C, minerals, residual heavy metals, and pesticides of various fresh-cut agri-food products were analysed. Sensory evaluation revealed that overall acceptability scores were less than expected in most products since fresh-cut products are likely to cause browning and easily lose their freshness. Therefore, the postharvest technologies that can maintain the quality, freshness and appearance must be supplied. Although vitamin C and minerals are main nutrients that can be supplied from salads, the results showed that vitamin C and mineral contents were very small and extremely small compared with the values from the food composition tables. It is possible that vitamin C and most minerals that are easily destroyed were lost through minimal processes like peeling and cutting. In safety side, the remaining heavy metal contents of fresh-cut agri-food were investigated and the results showed that copper and lead existed in some products because only cadmium in agricultural produce is controlled by the minimum standard of heavy metal contents in Korea. No residual pesticides were detected in all products.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.478-478
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• 2012

Recently, there are many researches in order to increase the deposition rate (D/R) and improve film uniformity and quality in the deposition of microcrystalline silicon thin film. These two factors are the most important issues in the fabrication of the thin film solar cell, and for the purpose of that, several process conditions, including the large area electrode (more than 1.1 X 1.3 (m2)), higher pressure (1 ~ 10 (Torr)), and very high frequency regime (VHF, 40 ~ 100 (MHz)), have been needed. But, in the case of large-area capacitively coupled discharges (CCP) driven at frequencies higher than the usual RF (13.56 (MHz)) frequency, the standing wave and skin effects should be the critical problems for obtaining the good plasma uniformity, and the ion damage on the thin film layer due to the high voltage between the substrate and the bulk plasma might cause the defects which degrade the film quality. In this study, we will propose the new concept of the large-area multi-electrode (a new multi-electrode concept for the large-area plasma source), which consists of a series of electrodes and grounds arranged by turns. The experimental results with this new electrode showed the processing performances of high D/R (1 ~ 2 (nm/sec)), controllable crystallinity (~70% and controllable), and good uniformity (less than 10%) at the conditions of the relatively high frequency of 40 MHz in the large-area electrode of 280 X 540 mm2. And, we also observed the SEM images of the deposited thin film at the conditions of peeling, normal microcrystalline, and powder formation, and discussed the mechanisms of the crystal formation and voids generation in the film in order to try the enhancement of the film quality compared to the cases of normal VHF capacitive discharges. Also, we will discuss the relation between the processing parameters (including gap length between electrode and substrate, operating pressure) and the processing results (D/R and crystallinity) with the process condition map for ${\mu}c$-Si:H formation at a fixed input power and gas flow rate. Finally, we will discuss the potential of the multi-electrode of the 3.5G-class large-area plasma processing (650 X 550 (mm2) to the possibility of the expansion of the new electrode concept to 8G class large-area plasma processing and the additional issues in order to improve the process efficiency.

• Journal of Food Hygiene and Safety
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• v.14 no.2
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• pp.201-215
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• 1999

Limited information is available on the acceptability of Korean MRLs(maximum residue limits) and the health risk based on the pesticide exposure by food intake. The aim of this study was to evaluate TMDI(theoretical maximum daily intake) and EDI(estimated daily intake) for Korean by using MRLs, food intake, residue data, and correction factors, and compare with ADI(acceptable daily intake) in order to estimate the health risk based on the pesticide exposure. The study was performed in three steps. In the frist step, the residual pesticides in each category of food were investigated using the pesticide residue analytical data(1995-96) from officially approved organizations and the analytical data for poultry was adopted from Korean food code method. In the second step, TMDI was estimated from MRLs and food factors, and was compared with ADI. In the third step, the effectiveness of each culinary treatment (washing, peeling, steaming, boiling, and salting) was evaluated and EDI was calculated using pesticide residue data, food factor, and correction factor by treatment. TMDI obtained from MRLs and food intake, and food intake was summed as 1,100.99 g, which was 79.1% of total consumption. The percent ratio of TMDI to ADI for 156 pesticides was mostly below 80% and only 30 pesticides exceeded the ADI. In particular, non-treated EDI from pesticide residue data and food intake was summed up to about 43 $\mu\textrm{g}$/day/capita, and the rank was procymidone(8.6 $\mu\textrm{g}$) > maleic hydrazide(8.2 $\mu\textrm{g}$) > EPN(3.7 $\mu\textrm{g}$) > deltamethrin(3.5 $\mu\textrm{g}$) > cypermethrin(3.0 $\mu\textrm{g}$). The treated EDI calculated from pesticide residue data, food intake, and correction factor by culinary treatment was summed up to 13.7 $\mu\textrm{g}$/day/captia. The percentage of ADI was TMDI(79.74%) > non-treated EDI (0.17%) > treated EDI (0.04%), and the exposure level of Korean population to whole pesticides was below the level to produce health risk. Oncogenic risk of five pesticides used in Korea whose oncogenic potency(Q*) was known were assessed from TMDI and treated EDI. Dietary oncogenic risk for Korean was estimated to be 2.0$\times$10-3 on the basis of TMDI, 8.3$\times$10-7 on the basis of treated EDI. The oncogenic risk from TMDI exceeded the risk level(1$\times$10-6) of EPA, whereas the oncogenic risk from treated EDI and real exposure level lower than that of EPA.

• Korean Journal of Food Science and Technology
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• v.13 no.3
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• pp.219-226
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• 1981

To enable off-season peach canning, peaches were halved and processed into solid packs. Following variables were compared in relation to storage stability of solid packs. First as pretreatment-dipping in citric and ascorbic solution after lye peeling; second as pasturization in pouch and hot fill process; third as packaging method-2 ply(PET/PE) and 3 ply(PET/Al/PE) plastic film pouch and metal container; fourth as storage condition $-20^{\circ}C\;and\;-5^{\circ}C$. After 25 weeks storage test, all peaches in different packs were processed into canned peaches just like commercial products, and then quality was organoleptically evaluated from the viewpoint of processing and storage variable of solid packs. The results are follows; 1. Ascorbic acid dipping in 3 ply pouch and citric acid dipping in 2 ply pouch had better quality retention effect than any other pretreatments in respective packing. 2. Pasteurization method gave great effect on the color and texture of the solid pack during storage, but not on the quality of the final canned peach. 3. Can and 3 ply packing were better than 2 ply pouch in storage of solid pack and quality of final canned peach. 4. The $5^{\circ}C$ storage gave better quality than $20^{\circ}C$.