• 대한소아치과학회지
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• 제35권3호
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• pp.446-455
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• 2008

이 연구의 목적은 법랑질 탈회부위에 불소 바니쉬 적용의 효과를 평가하는 것이다. 80개의 소의 법랑질 블록을 무작위로 4군으로 나누었다. 1군은 대조군으로 바니쉬 적용을 하지 않았다. 2군은 APF gel을 도포하고 4분후에 세척하였다. 3군과 4군은 Fluor $Protector^{(R)}$와 $CavityShield^{TM}$를 도포하고 1분 후에 세척하였다. 모든 표본을 인공우식용액 속에 넣어서 탈회시켰다. 가시광선 형광을 이용해 병소의 광밀도를 측정하고 병소의 깊이를 현미경으로 측정하고 통계적으로 비교하였다. 1. 48시간 후 광밀도 측정시 2군 광밀도는 대조군에 비해서 높았으나 바니쉬군보다 낮았고, 두 가지 바니쉬 간에 유의한 차이는 없었다. 2. 72시간 후 광밀도 측정결과 3군에서만 약간의 광밀도 감소가 관찰되고, 4군이 가장 높았다. 3. 72시간의 탈회 후 병소의 깊이를 측정한 결과 대조군에서는 평균 $205.36{\pm}42.85{\mu}m$, 2군에서 병소의 평균깊이는 $210.81{\pm}44.60{\mu}m$로 두 군간에 유의한 차이는 없었다. 4. 불소 바니쉬군의 병소 깊이는 3군이 $80.03{\pm}21.66{\mu}m$, 4군이 $77.46{\pm}27.72{\mu}m$로 대조군이나 2군에 비해 탈회가 억제되었음을 알 수 있었으나 두 가지 바니쉬 사이에 차이가 없었다.

• 한국음향학회지
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• 제42권5호
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• pp.412-421
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• 2023

초음파 뇌 자극술을 통하여 뇌 심부의 국소 지역에 있는 뇌 세포의 활성화를 유도할 수 있으며, 이를 통하여 저하된 뇌 기능을 치료하는데 효과가 있음이 보고되어 왔다. 반면, 초음파 자극의 종류에 따라 신경 변조의 효율과 방향이 달라질 수 있음이 알려져 있어, 적절한 초음파 자극의 종류를 확립하는 연구가 중요하다. 따라서, 본 논문에서는 이를 효과적으로 최적화 하기 위해 세포 배양시 사용되는 커버슬립 기반의 초음파 변환자를 제안하고자 한다. 균일한 초음파 자극을 전도하기 위해서 폴리머 압전소자(Poly-vinylidene fluoride-trifluorethylene, PVDF-TrFE)를 스핀 코팅하고 패를린 절연층을 상단에 적층시켜 음압 출력을 극대화 시켰다. 개발된 초음파 변환자 융합 커버슬립은 초음파자극기 표면에 배양된 수십개의 신경세포에 균일하고 정확한 초음파 자극을 전달 할 수 있고, 자극에 따른 세포의 반응을 형광 현미경으로 실시간 관찰 가능하다. 따라서, 동일한 초음파 자극에 대한 세포의 반응 신호를 최대 수십개 세포로부터 동시에 획득 가능하므로, 반응 신호를 평균 한다면 낮은 강도의 초음파 자극에 따른 뇌 세포의 미세한 반응을 검출할 수 있을 뿐만 아니라, 초음파 변환자와 물의 표면 등에서 발생하는 정현파에 의한 자극의 왜곡 현상을 줄일 수 있어서 사용자가 원하는 초음파 자극을 정확하게 세포로 전달 가능하다. 이렇게 개발된 초음파 변환자를 통해 변환자 표면에 배양된 별세포에서 6 MHz, 0.2 MPa의 저강도 초음파 자극에 의해 유도된 칼슘 반응을 성공적으로 관찰할 수 있었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.375-378
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• 2002

We investigated the reduction of etching damage by additive O$_2$ in etching gas and recovery of etching damage by O$_2$ annealing. The PZT thin films were etched using additive Ar or O$_2$ into Cl$_2$/CF$_4$ gas mixing ratio of 8/2. In order to recover ferroelectric properties of PZT thin films after etching, the etched PZT thin films were annealed at 600 C in O$_2$ atmosphere for 10 min. The remanent polarization is decreased seriously and fatigue is accelerated in the PZT sample etched in Ar/(C1$_2$+CF$_4$) plasma, whereas these characteristics are improved in O$_2$/(Cl$_2$/CF$_4$). From x-ray photoelectron spectroscopy (XPS) analysis, the intensities of Pb-O, Zr-O and Ti-O peaks are changed and the etch byproducts such as metal chloride and metal fluoride are reduced by O$_2$ annealing. From electron probe micro analyzer (EPMA) and auger electron spectroscopy(AES), O$_2$ vacancy is observed after etching. In x-ray diffraction (XRD), the structure damage in the additive O$_2$ into C1$_2$/CF$_4$ is reduced and the improvement of ferroelectric behavioral annealed sample is consistent with the increase of the (100) and (200) PZT peaks.

• Membrane and Water Treatment
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• 제11권4호
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• pp.237-245
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• 2020

The effects of the mixed two solvents, Dimethylacetamide (DMAc) and Dimethylformamide (DMF), and Polyethylene glycol (PEG) and Polyvinylpyrrolidone (PVP) as additives on performance of Polyvinylidene fluoride (PVDF) membranes were studied. Initially, PEG200 was used as a primary additive at fixed percentage of 5% wt. PVP was then blended with PEG200 in different concentrations. PVDF and DMAc were used as polymer and solvent in the casting solutions, respectively. To control the diffusion rate of PVP in the presence of PEG200 and PVP blend, mixtures of DMAc and DMF were used as the mixed solvent in the casting solutions. Asymmetric PVDF membranes were prepared via phase inversion process in a water bath and the effects of two additives and two solvents on the membrane morphology, pure water flux (PWF), hydrophilicity and rejection (R) were investigated. Attenuated Total Reflection Fourier Transform Infrared Spectra (ATR-FTIR) analysis was used to show the residual PVP on the surface of the membranes. Atomic Force Microscopy (AFM) was utilized to determine roughness of membrane surface. The use of mixed solvents in the casting solution resulted in reduction of PVP diffusion rate and increment of PEG diffusion rate. Eventually, PWF and R values reduced, while porosity and hydrophilicity increased.

• 상하수도학회지
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• 제32권5호
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• pp.453-460
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• 2018

The impact of sodium hydroxide, which is one of chemicals of clean in place (CIP) for removing membrane fouling, on the PVDF membrane is reviewed with respect to physical/chemical structural change, the permeability affected therefrom. Based on the cleaning concentration applied in membrane water treatment facilities, 10% of accumulated defluorination was confirmed up to 166g.hr/L which reflects the exposure time. However, membrane resistance was confirmed to be reduced by about 10%. Through FT-IR and EDS analysis, reduction of F and change of are confirmed as factors that affect the permeability of membrane. Membrane resistance, which affects permeability, is affected by loss of additives for hydrophilicity, rather than defluorination of PVDF material. Therefore, in order to check membrane degradation degree, an accelerated test by NaOH was carried out, loss of additives was confirmed, and then PVDF inherent characteristic was observed.

• Mycobiology
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• 제35권4호
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• pp.219-225
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• 2007

A keratinolytic enzyme secreted by Aspergillus flavus K-03 cultured in feather meal basal medium (FMBM) containing 2% (w/v) chicken feather was purified and characterized. Keratinolytic enzyme secretion was the maximal at day 16 of the incubation period at pH 8 and $28^{\circ}C$. No relationship was detected between enzyme yield and increase of fungal biomass. The fraction obtained at 80% ammonium sulfate saturation showed 2.39-fold purification and was further purified by gel filtration in Sephadex G-100 followed by ion exchange chromatography on DEAE-Sephadex A-50, yielding an active protein peak showing 11.53-fold purification. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and zymograms indicated that the purified keratinase is a monomeric enzyme with 31 kDa molecular weight. The extracellular keratinase of A. flavus was active in a board range of pH ($7{\sim}10$) and temperature ($30^{\circ}C{\sim}70^{\circ}C$) profiles with the optimal for keratinase activity at pH 8 and $45^{\circ}C$. The keratinase activity was totally inhibited by protease inhibitors such as phenylmethylsulfonyl fluoride (PMSF), iodoacetic acid, and ethylenediaminetetraacetate (EDTA) while no reduction of activity by the addition of dithiothreitol (DTT) was observed. N-terminal amino acid sequences were up to 80% homologous with the fungal subtilisins produced by Fusarium culmorum. Therefore, on the basis of these characteristics, the keratinase of A. flavus K-03 is determined to be subtilisins-like.

• 상하수도학회지
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• 제11권4호
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• pp.35-42
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• 1997

Recently fluoridation has often been considered as a method to maintain the concentration of fluoride in the drinking water at level adequate to be able to help protect children having decayed teeth. The benefits of fluoridation can be verified to compare the occurance rates of decayed tooth in the areas fluoridated and not fluoridated. Jainhae and Chongju have already fluoridaed the drinking water, and it was known that fluoridation could protect tooth-decaying effectively. The reduction rate of decayed teeth was estimated to be about 50~60 per cent. In the present study, a questionary survey to about sixty four hundred inhabitants of Taejon was carried out to grasp the opinions of citizens for fluoridation. According to the results, 75 per cent of the respondents agreed to the fluoridation. About 49 per cent and 44 per cent of them wanted that the fluoridation should be enforced after a questionary survey and after the decision of a specialist group in the institutes concerned respectively. About 71 per cent of them agreed to 5 per cent-rising of water fee for the fluoridation. The anual cost reguired for fluoridation in a large city was estimated to be about 500 won per capital therefore its economic effect is very large.

• 반도체디스플레이기술학회지
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• 제22권4호
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• pp.72-75
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• 2023

Carbon neutrality has been emerged as important mission for all the manufacturing industry to reduce energy usage and carbon emission equivalent. Korean semiconductor and display manufacturing industries are also in huge interest by minimize the energy usage as well as to find a less global warming product gases in both etch and cleaning. In addition, Korean government is also investing long term research and development plan for the safe environment in various ways. In this paper, we revisit previous research activities on carbon emission equivalent and current research activities performed in semiconductor process diagnosis research center at Myongji University with respect to the reduction of NF3 usage for the PECVD chamber cleaning, and we present the analytical result of the exhaust gas with residual gas analysis in both 6 inches and 12 inches PECVD equipment. The presented result can be a reference study of the development of new substitution gas in near future to compare the cleaning rate of the silicon oxide deposition chamber.

• Journal of Chest Surgery
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• 제21권5호
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• pp.803-815
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• 1988

The present experiments were performed to confirm the hypothesis that xanthine oxidase[XOD], as a source and mechanism of oxygen radical production, plays an important role in the genesis of the reperfusion injury of ischemic myocardium. The experimental ischemic-reperfusion injury was induced in isolated, Langendorff preparations of rat hearts by 60 min. Of global ischemia with aortic clamping followed by 20 min. of reperfusion with oxygenated Krebs-Henseleit solution[pH 7.4, 37*C]. The results were as follows: 1. The releases of creatine phosphokinase and a lipid peroxidation product, malondialdehyde[MDA] into the coronary effluent were abruptly increased upon reperfusion of ischemic hearts. The increases of the enzyme and MDA were suppressed significantly in the hearts removed from rats pretreated with allopurinol, a specific XOD inhibitor[20mg/kg, oral, 24 hrs and 2 hrs before study]. This effect of allopurinol was comparable to that of oxygen radical scavengers, superoxide dismutase[5, 000U] and catalase[12, 500 U]. 2. The increased SOD-inhibitable reduction of ferricytochrome C, which was infused to the hearts starting with reperfusion, was significantly suppressed in allopurinol pretreated hearts. 3. Activities of myocardial XOD were compared in the normal control hearts and the ischemic ones. Total enzyme activities were not different in both hearts. However, comparing with the control, the ischemic ones showed higher activity in 0-form and lower activities in D-form and D/O-form. 4. In the ischemic hearts, phenylmethylsulfonyl fluoride, a serine protease inhibitor, prevented significantly the increase of 0-form and the decreases of D and D/O-form, while thiol reagents did not affect the changes of the enzyme. 5. The increase of 0-form and the decreases of D and D/0-form were not significant in both calcium-free perfused and pimozide, a calmodulin inhibitor, treated ischemic hearts. 6. The SOD-inhibitable reduction of ferricytochrome C were suppressed by PMSF and pimozide treatment as well as by calcium-free perfusion. It is suggested from these results that in the ischemic rat myocardium, xanthine oxidase is converted to oxygen radical producing 0-form by calcium, calmodulin-dependent proteolysis and plays a contributing role in the genesis of ischemic-reperfusion injury by producing oxygen free radicals.

• Journal of Microbiology and Biotechnology
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• 제18권7호
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• pp.1317-1325
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• 2008

Viral safety is an important prerequisite for clinical preparations of plasma-derived pharmaceuticals. One potential way to increase the safety of therapeutic biological products is the use of a virus-retentive filter. In order to increase the viral safety of human antihemophilic factor IX, particularly in regard to non-enveloped viruses, a virus removal process using a polyvinylidene fluoride membrane filter (Viresolve NFP) has been optimized. The most critical factor affecting the filtration efficiency was operating pH and the optimum pH was 6 or 7. Flow rate increased with increasing operating pressure and temperature. Recovery yield in the optimized production-scale process was 96%. No substantial changes were observed in the physical and biochemical characteristics of the filtered factor IX in comparison with those before filtration. A 47-mm disk membrane filter was used to simulate the process performance of the production-scale cartridges and to test if it could remove several experimental model viruses for human pathogenic viruses, including human hepatitis A virus (HAV), porcine parvovirus (PPV), murine encephalomyocarditis virus (EMCV), human immunodeficiency virus type 1 (HIV), bovine viral diarrhea virus (BVDV), and bovine herpes virus (BHV). Non-enveloped viruses (HAV, PPV, and EMCV) as well as enveloped viruses (HIV, BVDV, and BHV) were completely removed during filtration. The log reduction factors achieved were $\geq$6.12 for HAV, $\geq$4.28 for PPV, $\geq$5.33 for EMCV, $\geq$5.51 for HIV, $\geq$5.17 for BVDV, and $\geq$5.75 for BHV. These results indicate that the virus filtration process successfully improved the viral safety of factor IX.