• Journal of Sensor Science and Technology
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• v.2 no.1
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• pp.81-86
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• 1993

Polycrystalline CdSe thin films were grown on ceramic substrate using a chemical bath deposition (CBD) method. They were annealed at various temperature and X-ray diffraction patterns were measured by X-ray diffractometer in order to study CdSe polycrystal structure. Using extrapolation method of X-ray diffraction patterns for the CdSe samples annealed in $N_{2}$ gas at $450^{\circ}C$ it was found hexagonal structure whose lattice parameters $a_{o}$ and $c_{o}$ were $4.302{\AA}$ and $7.014{\AA}$, respectively. Its grain size was about $0.3{\mu}m$. Hall effect on this sample was measured by Van der Pauw method and studied on carrier density and mobility depending on temperature. From Hall data, the mobility was likely to be decreased by piezo electric scattering at temperature range of 33 K and 200 K, and by polar optical scattering at temperature range of 200 K and 293 K. We measured also spectral response, sensitivity (${\gamma}$), maximum allowable power dissipation and response time on these samples.

• Restorative Dentistry and Endodontics
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• v.35 no.5
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• pp.359-367
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• 2010

Objectives: The purpose of the present in vitro study was to evaluate the biocompatibility of mineral trioxide aggregate (MTA) mixed with glass ionomer cement (GIC), and to compare it with that of MTA, GIC, IRM and SuperEBA. Materials and Methods: Experimental groups were divided into 3 groups such as 1 : 1, 2 : 1, and 1 : 2 groups depending on the mixing ratios of MTA powder and GIC powder. Instead of distilled water, GIC liquid was mixed with the powder. This study was carried out using MG-63 cells derived from human osteosarcoma. They were incubated for 1 day on the surfaces of disc samples and examined by scanning electron microscopy. To evaluate the cytotoxicity of test materials quantitatively, XTT assay was used. The cells were exposed to the extracts and incubated. Cell viability was recorded by measuring the optical density of each test well in reference to controls. Results: The SEM revealed that elongated, dense, and almost confluent cells were observed in the cultures of MTA mixed with GIC, MTA and GIC. On the contrary, cells on the surface of IRM or SuperEBA were round in shape. In XTT assay, cell viability of MTA mixed with GIC group was similar to that of MTA or GIC at all time points. IRM and SuperEBA showed significantly lower cell viability than other groups at all time points (p < 0.05). Conclusions: In this research MTA mixed with GIC showed similar cellular responses as MTA and GIC. It suggests that MTA mixed with GIC has good biocompatibility like MTA and GIC.

• Restorative Dentistry and Endodontics
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• v.34 no.6
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• pp.491-499
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• 2009

This study examined the influence of the storage methods on the viability of oral epithelial cells using conventional cell freezing storage, slow freezing preservation, rapid freezing preservation, and slow freezing preservation with a pressure of 2 Mpa or 3 Mpa. The cell viability was evaluated by cell counting, WST-1 and the clonogenic capacity after 6 days of freezing storage. After 6 days, the frozen cells were thawed rapidly, and the cell counting. WST-1, and clonogenic capacity values were measured and compared. 1. The results from cell counting demonstrated that conventional cryopreservation, slow freezing under a 2 Mpa pressure and slow freezing under a 3 Mpa pressure showed significantly higher values than slow freezing preservation and rapid freezing preservation (p < 0.05). 2. The results from the optical density by WST-1 demonstrated that slow freezing under a 2 Mpa pressure showed significantly higher values than slow freezing preservation and rapid freezing preservation (p<0.05). 3. The clonogenic capacity demonstrated that slow freezing under a 2 Mpa pressure showed significantly higher values than slow freezing preservation and rapid freezing preservation (p < 0.05).

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.3
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• pp.182-187
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• 2011

In this paper, PBTI characteristics of NMOSFETs with La incorporated HfSiON and HfON are compared in detail. The charge trapping model shows that threshold voltage shift (${\Delta}V_{\mathrm{T}}$) of NMOSFETs with HfLaON is greater than that of HfLaSiON. PBTI lifetime of HfLaSiON is also greater than that of HfLaON by about 2~3 orders of magnitude. Therefore, high charge trapping rate of HfLaON can be explained by higher trap density than HfLaSiON. The different de-trapping behavior under recovery stress can be explained by the stable energy for U-trap model, which is related to trap energy level at zero electric field in high-k dielectric. The trap energy level of two devices at zero electric field, which is extracted using Frenkel-poole emission model, is 1,658 eV for HfLaSiON and 1,730 eV for HfLaON, respectively. Moreover, the optical phonon energy of HfLaON extracted from the thermally activated gate current is greater than that of HfLaSiON.

• Polymer(Korea)
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• v.37 no.6
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• pp.744-752
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• 2013

The miscibility between poly(L-lactide) (PLLA) and poly(methyl methacrylate) (PMMA) was investigated using thermal analyses for the purpose of developing birefringence-free material at oriented state. The effect of methyl acrylate (MA) units as comonomer of PMMA on the miscibility was also studied. All the blends prepared in this study show composition-dependent single $T_g$'s between those of blend components and high transparency over the visible region, indicating the miscibility at molecular level and no discernible effect of MA units on it. No phase separation was observed at elevated temperature of $280^{\circ}C$, higher than the degradation of PLLA and PMMA. The interaction energy density in PLLA/PMMA blends with 17 mol% of MA was measured to be $-0.74J/cm^3$ from the equilibrium melting temperature depression based on the Hoffman-Weeks method. The blends show zero-${\Delta}$n behavior at a specific mixing ratio and the drawing ratio of 3 due to compensation of intrinsic orientation birefringence. Birefringence dispersion of PLLA/PMMA5 blends was also measured to examine the possibility for quarter-wave plates or polarizer protective films.

• The Journal of Korean Physical Therapy
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• v.14 no.2
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• pp.162-171
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• 2002

The purpose of this study was to examined whether high voltage pulsed current stimulation(HVPCS) enhances the migration and proliferation of fibroblasts from tendon biopsies to provides evidence that the cellular activities of fibroblast are enhanced by HVPCS. Flexor digitorum profundus tendon of chickens were excised, biopsied and cultured in M199 medium for a day. The biopsies through which a cathodal HVPC with 100 pps, 50 V for 30 minutes was passed in medium. A day after treatment, the biopsies embedded in fibrin clot were covered by the addition of 1ml of M199 medium to the well, and placed in the $CO_2$ incubator for the duration of the experiment. The migration distance of cells from tendon biopsies were measured at 6 days after treatment, and proliferation of cells from tendon biopsies were measured at 7 days after treatment. The migration distance of cells from tendon biopsies in the HVPCS group demonstrated significantly greater than the shame treated control group (t=-2.675, p<0.05). Also HVPCS had significantly increased optical density of fibroblasts from tendon biopsies (t=-2.136, p<0.05). These results indicate that the HVPCS with 100pps, 50V for 30minutes enhanced either the migration and proliferation of fibroblast from tendon biopsies. These results supposed that the HVPCS activates cellular responses in fibroblasts from tendon biopsies. This suggests that enhanced the migration and proliferation of fibroblast by HVPCS may be one of the mechanism involved in tendon healing.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.42 no.5
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• pp.37-46
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• 2010

This study was carried out to develop new application field and obtain the basic data of mixed paper with wood pulp and chitosan fiber for producing functional paper. Two types of wood pulp, such as SwBKP and HwBKP, were mixed with chitosan fiber. Physical and optical properties, water vapor absorption, air permeability, antibacterial activity and ash were measured. And the surface morphology of manufactured paper was observed using SEM. The results are as follows. It was revealed that density, breaking length, burst index, tear index, folding endurance and brightness were reduced but water vapor absorption and air permeability were on the rise in the structural view of SwBKP according to increasing the chitosan fiber ratio. Those HwBKP added chitosan fiber were great not only in the strength but also water vapor absorption and air permeability except for brightness. The water vapor absorption was lower and the air permeability was higher in the HwBKP added various chitosan fiber ratios than those with no chitosan fiber. It is estimated that these properties were related with various mixed rate of chitosan fiber. Particularly, air permeability was strongly dependent on the mixed rate of chitosan fiber. The chitosan fiber has superior antibacterial property, comparing with wood fiber. Adding chitosan fiber to the wood pulp was found to have an excellent antibacterial activity, more than 90%. The ashes were determined within 0.5%. Special bonds between chitosan fiber and wood pulp was observed by SEM and it means that the chitosan fiber were combined equally in the interior of wood pulp. In conclusion, mixing wood pulp with chitosan fiber can not only improves the quality of paper but also extend the usage of paper as a functional paper by using inherent property of chitosan. After all, production of functional paper added chitosan fiber is expected for new valuable industry of paper.

• The Journal of Internal Korean Medicine
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• v.24 no.2
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• pp.337-347
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• 2003

This study investigated the effect of Yanggyuksanhwa-tang on cerebral ischemia of the rats. Considering age-related impact on cerebral ischemia, aged rats (18 months old) were used for this study. Ischemic damage was induced by the transient occlusion of bilateral common carotid arteries(BCAO) under the hypotension. Yanggyuksanhwa-tang was administered twice orally. Then changes of immunohistochemical expression of c-fos and c-jun in ischemic damaged hippocampus were observed. The BCAO in aged rats led significant increase of c-fos expression in CA1 and DG of hippocampus. While the treatment of Yanggyuksanhwa-tang significantly attenuated the increase of c-fos expression in CA1 hippocampus following BCAO ischemia. Depending on changes of the normalized optical density(NOD) of immunohistochemical c-fos expression, the treatment of Yanggyuksanhwa-tang significantly attenuated the increase of NOD in CA1 and DG of hippocampus. And there was not changes in CA2 and CA3 hippocampus with respect to the control BCAO group. The BCAO in aged rats led significant increase of c-jun expression in CA1 hippocampus. While the treatment of Yanggyuksanhwa-tang significantly attenuated the increase of c-jun expression in CA1 hippocampus following BCAO ischemia. Depending on changes of the NOD of immunohistochemical c-jun expression, the treatment of Yanggyuksanhwa-tang significantly attenuated the increase of NOD in CA1 hippocampus. And there was not changes in CA2, CA3 and DG of hippocampus with respect to the control BCAO group.

• Korean Journal of Pharmacognosy
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• v.36 no.3 s.142
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• pp.164-170
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• 2005

In the present study, we investigated the mineral and metabolite composition and antioxidant activities in the flower, stem and root of Aster ciliosus Kitamura in order to detect biologically active substances and develop novel functional resources. The mineral and metabolite compositions differ significantly among the organ of Aster ciliosus Kitamura. The flower is composed of K as 827 mg/100g. while the stem and root are composed of Na as 654.64mg/100g and 771.70mg/100g, respectively. Contents of unsaturated fatty acids, such as oleic, linoleic, and linolenic acid, were higher than those of saturated fatty acid, such as palmitic acid in flower. The contests of phenolic compounds were measured at 285 nm using different solvents: 2.53 and 2.03 optical density (OD) in chloroform and 1.864 and 1.715 in ethanol extracts for the stem and root, respectively. Antioxidant activity was measured in 75% ethanol extracts: 41.3, 42.0 and $45.2\;{\mu}g/ml$ in stem, root and flower at $IC_{50}$ value, respectively. These results suggest that extracts from Aster ciliosus Kitamura can be potentially used as novel resources for antioxidant and biological active substances.

• Journal of Life Science
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• v.15 no.6 s.73
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• pp.847-850
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• 2005

The aim of this study was to increase production of leucocin A, a kind of bacteriocin, in a transformed variety of S. cerevisiae. We investigated optical density, total secreted protein, protease activity, and antibacterial activity for the transformed S. cerevisiae in different carbon sources. The production of leucocin A growth-associated, and antibacterial activity, according to carbon source, was in the order of sucrose, glucose, glycerol, and fructose. Antibacterial activity was $10.6\%$ higher in the presence of sucrose than glucose. This is the first report regarding the effect of carbon sources on the production of leucocin A in transformed S. cerevisiae, as far as we ascertain. Our results could prove useful in the industrial production of natural preservatives.