• Journal of Periodontal and Implant Science
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• 제25권3호
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• pp.478-486
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• 1995

Periodontal therapy for treatment of periodontitis involves the elimination of bacterial plaque and elimination of the anatomic defects by regenerative procedure. The purpose of this study was to evaluate on the biological effect of magnolia and Ginkgo biloba extract to the antimicrobial, antiinflammatory and cellular activity. Antimicrobial assay was performed with the diffusion method of the extract by measuring of growth inhibitory zone of B. cereus from blood agar plate. Effect of the extract to cellular activity of gingival fibroblast were examined using MTT method and measured the result with optical density on 570nm by ELISA reader. Inhibitory effects of $PGE_2$ production from gingival fibroblast was performed with the addition of $IL-l{\beta}$ and the extract to the well and examined to the product of $PGE_2$ from cell by ELISA reader. In vivo anti-inflammatory effect was performed with injection examined with clinically and histologically for their extent of mecrosis and inflammation. Antimicrobial activity of Magnolia extract showed significantly higher activity than that of control. However, GBE did not showed significant activity to compare with control, and mixture of Magnolia and GBE extract showed significantly higher activity than that of control. The effect of cellular activity to gingival fibroblast showed no significant differences of between control and Magnolia extract. However, GBE showed significantly higher rate of cellular activity to compare with control and even to PDGF-BB, and also showed same degree of cellular activity even though mixed with Magnolia extract. The inhibitory effect of $PGE_2$ production showed significantly reduction of $PGE_2$ production to compare with control, but its inhibitory effect was not much strong to compare with Indomethacin. In vivo, antiinflammatory effect of Magnolia extract to P. gingivalis injection of Hamster buccal check showed significantly reduction of inflammatory cell infiltration and tissue necrosis, but GBE showed no effect on the inhibition of inflammatory process. These results suggested that Magnolia and GBE extract possessed different kind of biological activity and also can be compensated on their activity with each other for elimination of bacterial plaque and anatonical defect.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.1
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• pp.352-356
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• 2003

A stoichiometric mixture of evaporating materials for $CuGaSe_2$ single crystal am films was prepared from horizontal electric furnace. Using extrapolation method of X-ray diffraction patterns for the polycrystal $CuGaSe_2$, it was found tetragonal structure whose lattice constant $a_0$ and $c_0$ were $5.615\;{\AA}\;and\;11.025\;{\AA}$, respectively. To obtain the single crystal thin films, $CuGaSe_2$ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the hot wall epitaxy (HWE) system. The source and substrate temperatures were $610^{\circ}C$ and $450^{\circ}C$, respectively, The crystalline structure of the single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The carrier density and mobility of $CuGaSe_2$ single crystal thin films measured with Hall effect by van der Pauw method are $9.24{\times}10^{16}\;cm^{-3}$ and $295\;cm^2/V{\cdot}s$ at 293 K, respectively. The temperature dependence of the energy band gap of the $CuGaSe_2$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)\;:\;1.7998\;eV\;-\;(8.7489\;{\times}\;10^{-4}\;eV/K)T^2(T\;+\;335\;K)$. After the as-grown $CuGaSe_2$ single crystal thin films was annealed in Cu-, Se-, and Ga-atmospheres, the origin of point defects of $CuGaSe_2$ single crystal thin films has been investigated by the photoluminescence(PL) at 10 K. The native defects of $V_{CU}$, $V_{Se}$, $CU_{int}$, and $Se_{int}$, obtained by PL measurements were classified as a donors or accepters type. And we concluded that the heat-treatment in the Cu-atmosphere converted $CuGaSe_2$ single crystal thin films to an optical n-type. Also, we confirmed that Ga in $CuGaSe_2/GaAs$ did not form the native defects because Ga in $CuGaSe_2$ single crystal thin films existed in the form of stable bonds.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 2005년도 추계학술대회 논문집 Vol.18
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• pp.111-112
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• 2005

To obtain the single crystal thin films, $CuInSe_2$, mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the hot wail epitaxy (HWE) system. The source and substrate temperatures were 620$^{\circ}C$ and 410$^{\circ}C$, respectively. The crystalline structure of the single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The carrier density and mobilily of $CuInSe_2$ single crystal thin films measured with Hall effect by van der Pauw method are $9.62\times10^{16}$ $cm^{-3}$ and $296cm^2/V{\cdot}s$ at 293 K, respectively. The temperature dependence of the energy band gap of the CulnSe$_2$ obtained from the absorption spectra was well described by the Varshni's relation E$_g$(T) = 1.1851 eV - ($8.99\times10^{-4}$ ev/K)T$_2$/(T + 153K). After the as-grown $CuInSe_2$ single crystal thin films was annealed in Cu-, Se-, and In-atmospheres the origin of point defects of $CuInSe_2$ single crystal thin films has been investigated by the photoluminescence(PL) at 10 K. The nat ive defects of V$_{Cu}$, $V_{Se}$, Cu$_{int}$, and $Se_{int}$ obtained by PL measurements were classified as a donors or accepters type. And we concluded that the heat-treatment in the Cu-atmosphere converted $CuInSe_2$ single crystal thin films to an optical n-type. Also, we confirmed that In in $CuInSe_2$/GaAs did not form the native defects because In in $CuInSe_2$ single crystal thin films existed in the form of stable bonds.

• Journal of radiological science and technology
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• 제28권4호
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• pp.267-272
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• 2005

The effects of As addition in amorphous selenium (a-Se) films for digital X-ray conversion material have been studied using the moving photocarrier grating (MPG) technique. This method utilizes the moving interference pattern generated by the superposition of the two frequency shifted laser beams for the illumination of the sample. This moving intensity grating induces a short circuit current, jsc in a-Se:As film. The transport parameters of the sample are extracted from the grating-velocity dependent short circuit current induced in the sample along the modulation direction. The electron and hole mobility, and recombination lifetime of a-Se films with arsenic (As) additions have been obtained. We have found an increase in hole drift mobility and recombination lifetime, especially when 0.3% As is added into a-Se film, whereas electron mobility decreases with As addition due to the defect density. The transport properties for As doped a-Se films obtained by using MPG technique have been compared with X-ray sensitivity for a-Se:As device. The fabricated a-Se(0.3% As) device film exhibited the highest X-ray sensitivity out of 5 samples.

• Journal of the Korean Vacuum Society
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• 제2권2호
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• pp.188-198
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• 1993

We have developed a technique for growing thin oxides (6~10 nm) by the Last step TCA method. N-channel metal-oxide-semiconductor (n-MOS) capacitor and n-channel metal-oxide-semiconductor field-effect transistor's (MOSFET's) having a gate oxide with chlorine incorporated $SiO_2/Si$ interface have been analyzed by electrical measurements and physical methods, such as secondary ion mass spectrometry (SIMS) and electron spectroscopy for chemical analysis (ESCA). The gate oxide grown with the Last strp TCA method has good characteristics as follows: the electron mobility of the MOSFET's with the Last step TCA method was increased by about 7% and the defect density at the $SiO_2/Si$ interface decreases slightly compared with that with No TCA method. In reliability estimation, the breakdown field was 18 MV/cm, 0.6 MV/cm higher than that of the gate oxide with No TCA method, and the lifetime estimated by TDDB measurement was longer than 20 years. The device lifetime estimated from hot-carrier reliability was proven to be enhanced. As the results, the gate oxide having a $SiO_2/Si$ interface incorporated with chlorine has good characteristics. Our new technique of Last step TCA method may be used to improve the endurance and retention of MOSFET's and to alleviate the degradation of thin oxides in short-channel MOS devices.

• Korean Journal of Materials Research
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• 제23권12호
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• pp.714-721
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• 2013

A stoichiometric mixture of evaporating materials for $ZnAl_2Se_4$ single-crystal thin films was prepared in a horizontal electric furnace. These $ZnAl_2Se_4$ polycrystals had a defect chalcopyrite structure, and its lattice constants were $a_0=5.5563{\AA}$ and $c_0=10.8897{\AA}$.To obtain a single-crystal thin film, mixed $ZnAl_2Se_4$ crystal was deposited on the thoroughly etched semi-insulating GaAs(100) substrate by a hot wall epitaxy (HWE) system. The source and the substrate temperatures were $620^{\circ}C$ and $400^{\circ}C$, respectively. The crystalline structure of the single-crystal thin film was investigated by using a double crystal X-ray rocking curve and X-ray diffraction ${\omega}-2{\theta}$ scans. The carrier density and mobility of the $ZnAl_2Se_4$ single-crystal thin film were $8.23{\times}10^{16}cm^{-3}$ and $287m^2/vs$ at 293 K, respectively. To identify the band gap energy, the optical absorption spectra of the $ZnAl_2Se_4$ single-crystal thin film was investigated in the temperature region of 10-293 K. The temperature dependence of the direct optical energy gap is well presented by Varshni's relation: $E_g(T)=E_g(0)-({\alpha}T^2/T+{\beta})$. The constants of Varshni's equation had the values of $E_g(0)=3.5269eV$, ${\alpha}=2.03{\times}10^{-3}eV/K$ and ${\beta}=501.9K$ for the $ZnAl_2Se_4$ single-crystal thin film. The crystal field and the spin-orbit splitting energies for the valence band of the $ZnAl_2Se_4$ were estimated to be 109.5 meV and 124.6 meV, respectively, by means of the photocurrent spectra and the Hopfield quasicubic model. These results indicate that splitting of the ${\Delta}so$ definitely exists in the ${\Gamma}_5$ states of the valence band of the $ZnAl_2Se_4/GaAs$ epilayer. The three photocurrent peaks observed at 10 K are ascribed to the $A_1$-, $B_1$-exciton for n = 1 and $C_{21}$-exciton peaks for n = 21.

• Journal of Periodontal and Implant Science
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• 제27권1호
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• pp.165-177
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• 1997

The purpose of this study was to perform on the biological activity of Magnolia and Zizyphi fructus extract mixtures on the wound healing of defected rat calvaria. For the determination of the mixture ratio of two extracts for oral administration, preliminary experiments were performed with the mixture combination of 2000 and $3000{\mu}g/ml$ of Magnolia extract, and also 20, 30, 200, 300, 2000 and $3000{\mu}g/ml$ of Zizyphi fructus extract, respectively and divided into 6 groups. The combination of extracts mixture were tested on the enhancing effect of cellular activity. The effect of the extracts mixture on the cellular activity was evaluated using MTT method and measured on the results with optical density by ELISA reader. The ability to tissue regeneration of the extracts mixture was performed by measuring new bone and new connective tissue regeneration on the 5mm defected rat calvaria for 1, 2 and 3 weeks after oral administration of 2 different dosages groups : 10:1(0.1g/kg) and 10:1(0.5g/kg). It was employed the same dosages of unsaponifiable fraction of Zea Mays L as positive controls. Each group of rat was sacrificed and en bloc section for histological examination. The effect on the cellular activity of each mixture ratio showed significantly higher in $2000{\mu}g/ml$ of Magnolia extract and $200{\mu}g/ml$ of Zizyphi fructus extract group to compare with other groups. These preliminary results showed that appropriate mixture ratio of two extracts was 10:1 of Magnolia and Zizyphi fructus extract. Histological examination on the activity of tissue regeneration of each group showed that 2weeks and 3weeks specimens of 0.5g/kg of 10:1 extract mixture of Magnolia and Ziziphi fructus administrated rat calvaria revealed significantly more osteoid and new bone formation of defected calvaria with unification of defected area than the specimens of any other negative and positive controls. Even though the specimen administrated the same dosages of unsaponifiable fraction of Zea Mays L, positive controls, showed the trend that they promote significantly the repair of calvarial defect, their bone reparative activities were less inductive than the same dosages of Magnolia and Ziziphi fructus extract mixture. These results implicated that the mixture of Magnolia and Zizyphi fructus extracts should be highly effective on the wound healing of bony defected site and might have potential possibilities as an useful drug to promote periodontal tissue regeneration.

• Korean Journal of Crystallography
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• 제4권2호
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• pp.74-85
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• 1993

Single crystals of LiNbO3 have found extensive application in electro-optic and nonlinear optic devices. However, laser-induced refartive index inhomogeneities, which have been labeled opical damage impose limits on device optical damage in LiNbO3 is imporved if more than 4.5 rml% MgO is added to the melt The laser damage thrueshold increased as much as 100 times better then that of undoped crystals. The MgO doped cystal has thus been urterlsiv81y studied since then. In the study, Mgo:LiNbOs(MLA) single crystals dopsd with 0, 2.5, 5.0, 7.5, 10.0 mol% MgO have been grown by the czocrualski technique. The metls were prepared in the platinum crluible and 15∼20mm diameter crystals were grown with a length of 20∼30mm in a resitance heater. The growth rate was 2.5mm/hr, the rotation speed 15rpn. Before sawing MLN single crystals were annealed for 24 hours under atmosphere at a temperature of 1080℃. After sawing, we have found an annual ring cross section of MNA crystals only in the direction of perpendicilar to the c-axis. Nonuniform dispusion of MgO was pointed out that the cuties of the state of oxide were strongly affected by oxygen partial pressure in.

• Journal of Veterinary Clinics
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• 제27권5호
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• pp.600-604
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• 2010

A ten-year-old female mongrel dog was presented to Veterinary Medical Center, Chungbuk National University with the signs of anorexia, weakness, and hemoglobinuria. Patient had been diagnosed as dirofilariasis based on heartworm antigen test and treated with adulticide (melarsomine) at local hospital one day before admission. On laboratory examinations, there were hypochromic and microcytic regenerative anemia, thrombocytopenia, moderate neutrophilia, and increase ALT, AST, and ALP. Radiographic exam showed main pulmonary artery bulging, pulmonary infiltration and hypervascularity, reduced abdominal serosal detail and mild hepatomegaly. Abdominal ultrasonographic exam showed mild peritoneal effusion and large hyperechoic thrombi at trifurcation of the porta hepatica and the splenic vein. In addition, intraluminal low density area and intravascular filling defect were confirmed on contrast enhanced CT scanning at the same anatomic locations. Patient was treated with anticoagulant and thrombolytic therapy. On day 42 after treatment, complete resolution of thrombi was confirmed via ultrasonography and improvement of clinical signs was observed.

• Journal of the Korean Crystal Growth and Crystal Technology
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• 제25권4호
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• pp.127-134
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• 2015

Aluminum nitride (AlN) single crystals have attracted much attention for a next-generation semiconductor application because of wide bandgap (6.2 eV), high thermal conductivity ($285W/m{\cdot}K$), high electrical resistivity (${\geq}10^{14}{\Omega}{\cdot}cm$), and high mechanical strength. The bulk AlN single crystals or thin film templates have been mainly grown by PVT (sublimation) method, flux method, solution growth method, and hydride vapor phase epitaxy (HVPE) method. Since AlN suffers difficulty in commercialization due to the defects that occur during single crystal growth, crystalline quality improvement via defects analyses is necessary. Etch pit density (EPD) analysis showed that the growth misorientations and the defects in the AlN surface exist. Transmission electron microscopy (TEM) and electron back-scattered diffraction (EBSD) analyses were employed to investigate the overall crystalline quality and various kinds of defects. TEM studies show that the morphology of the AlN is clearly influenced by stacking fault, dislocation, second phase, etc. In addition EBSD analysis also showed that the zinc blende polymorph of AlN exists as a growth defects resulting in dislocation initiator.