Cu 기판위에 성장한 MgO, MgAl₂O₄와 MgAl₂O₄/MgO 박막의 집속이온빔을 이용한 스퍼터링수율 측정과 이차전자방출계수 측정

정강원(K. W. Jung),이혜정(H. J. Lee),정원희(W. H. Jung),오현주(H. J. Oh),박철우(C. W. Park),최은하(E. H. Choi),서윤호(Y. H. Seo),강승언(S. O. Kang) 한국진공학회(ASCT) 2006 Applied Science and Convergence Technology Vol.15 No.4

MgAl₂O₄ 막은 MgO 보호막 보다 단단하며 수분 흡착 오염문제에 상당히 강한 특성을 가진다. 본 연구에서 AC-PDP의 유전체보호막으로 사용되는 MgO 보호막의 특성을 개선하기 위해 MgAl₂O₄/MgO 이중층 보호막을 제작하여 특성을 조사하였다. 전자빔 증착기를 사용하여 Cu 기판에 MgO와 MgAl₂O₄을 각각 1000 Å 두께로 증착, MgAl₂O₄/MgO을 200/800 Å 두께로 적층 증착 후, 이온빔에 의한 충전현상을 제거하기 위해 Al을 1000 Å 두께로 증착하였다. 집속 이온빔(focused ion beam ; FIB)장치를 이용하여 10 ㎸에서 14 ㎸까지 이온빔 에너지에 따라 MgO는 0.364 ~ 0.449 값의 스퍼터링 수율에서 MgAl₂O₄/MgO을 적층함으로 24 ~ 30 % 낮아진 0.244 ~ 0.357 값의 스퍼터링 수율이 측정되었으며, MgAl₂O₄는 가장 낮은 0.088 ~ 0.109 값의 스퍼터링 수율이 측정되었다. g-집속이온빔(g-FIB)장치를 이용하여 Ne? 이온 에너지를 50 V에서 200 V까지 변화 시켜 MgAl₂O₄/MgO와 MgO는 0.09 ~ 0.12의 비슷한 이차전자방출 계수를 측정 하였다. AC-PDP셀의 72시간 열화실험 후 SEM 및 AFM으로 열화된 보호막의 표면을 관찰하여 기존의 단일 MgO 보호막과 MgAl₂O₄/MgO의 적층보호막의 열화특성을 살펴보았다. It is known that MgAl₂O₄ has higher resistance to moisture than MgO, in humid ambient MgO is chemically unstable. It reacts very easily with moisture in the air. In this study, the characteristic of MgAl₂O₄ and MgAl₂O₄/MgO layers as dielectric protection layers for AC-PDP (Plasma Display Panel) have been investigated and analysed in comparison for conventional MgO layers. MgO and MgAl₂O₄ films both with a thickness of 1000 Å and MgAl₂O₄/MgO film with a thickness of 200/800 Å were grown on the Cu substrates using the electron beam evaporation. 1000 Å thick aluminium layers were deposited on the protective layes in order to avoid the charging effect of Ga? ion beam while the focused ion beam(FIB)is being used. We obtained sputtering yieds for the MgO, MgAl₂O₄ and MgAl₂O₄/MgO films using the FIB system. MgAl₂O₄/MgO protective layers have been found th show 24 ~ 30% lower sputtering yield values from 0.244 up to 0.357 than MgO layers with the values from 0.364 up to 0.449 for irradiated Ga? ion beam with energies ranged from 10 ㎸ to 14 ㎸. And MgAl₂O₄ layers have been found to show lowest sputtering yield values from 0.88 up to 0.109. Secondary electron emission coefficient(g) using the γ-FIB. MgAl₂O₄/MgO and MgO have been found to have similar g values from 0.09 up to 0.12 for indicated Ne+ ion with energies ranged from 50 V to 200 V. Observed images for the surfaces of MgO and MgAl₂O₄/MgO protective layers, after discharge degradation process for 72 hours by SEM and AFM. It is found that MgAl₂O₄/MgO protective layer has superior hardness and degradation resistance properties to MgO protective layer.

An albumin nanocomplex-based endosomal pH-activatable on/off probe system

Lee, C.,Lee, S.,Thao, L.Q.,Hwang, H.S.,Kim, J.O.,Lee, E.S.,Oh, K.T.,Shin, B.S.,Choi, H.G.,Youn, Y.S. Elsevier 2016 Colloids and Surfaces B Vol.144 No.-

<P>Albumin has gained considerable interest as a material for fabricating nanoparticulate systems due to its biomedical advantages, such as biocompatibility and chemical functionality. Here, we report a new pH-sensitive albumin nanocomplex prototype with a zinc-imidazole coordination bond. Albumin was conjugated with 1-(3-aminopropyl)imidazole and mPEG(10kDa)-NHS, and the resulting albumin conjugate (PBI) was then modified with either Cy5.5 or BHQ-3. The newly formed albumin nanocomplex (C/BQ-PBI Zn NCs: similar to 116 nm) system was facilely self-assembled around pH 7.4 in the presence of Zn2+, but it quickly disassembled in an acidic environment (similar to pH 5.0). Based on this pH-sensitivity, C/BQ-PBI Zn NCs emitted strong near-infrared fluorescence and released Zn2+, turning 'off' at pH similar to 7.4 (e.g., plasma) and 'on' at pH similar to 5.0 (e.g., endo/lysosomes in tumor cells) on account of fluorescence resonance energy transfer. C/BQ-PBI Zn NCs displayed significant cytotoxicity due to an increase in cellular. Zn2+ in response to endosomal pH (similar to 5.0) in breast cancer MCF-7 cells and lung adenocarcinoma A549 cells. Particularly, confocal laser scanning microscopic images showed a strong fluorescence signal caused by the disassembly of C/BQ-PBI Zn NCs in the endosomal region of MCF-7 cells. Based on these results, we believe that this albumin nanocomplex is an attractive biocompatible tumor targeting probe carrier for the theranostic purpose. (C) 2016 Elsevier B.V. All rights reserved.</P>

A simulation study on the direct carbothermal reduction of SiO₂for Si metal

Lee, H.C.,Dhage, S.,Akhtar, M.S.,Kwak, D.H.,Lee, W.J.,Kim, C.Y.,Yang, O.B. Elsevier 2010 CURRENT APPLIED PHYSICS Vol.10 No.2

The direct carbothermal reduction of SiO<SUB>2</SUB>to Si metal was simulated as a function of mole ratio of SiO<SUB>2</SUB> SiC and C in the temperature range of 0-3000<SUP>o</SUP> by using a thermodynamic calculation of Gibb's free-energy minimization. In the SiO<SUB>2</SUB>C system, the silicon metal was formed from the 1250<SUP>o</SUP> and completed at 1500-2000<SUP>o</SUP> with the excess amount of C. By the addition of SiC in SiO<SUB>2</SUB>C carbothermal reduction system, complete conversion of SiO<SUB>2</SUB>to Si could be promoted through the lowering the reaction temperature and the excess carbon. Methane gas was efficient reducing agent of SiO<SUB>2</SUB>to form Si metal at around 2000<SUP>o</SUP>, while H<SUB>2</SUB>and CO could not reduce SiO<SUB>2</SUB>to Si at any conditions. The simulated results were consistent with the experimental works carried out in the arc furnace.

Influence of Annealing Temperature on Magnetoelectric Properties of CoFe2O4/Pt/Pb(Zr0.3Ti0.7)O3 Thin Films

Eum, Y.J.,Hwang, S.-O.,Ryu, J.,Kim, J.-W.,Koo, C.Y.,Lee, J.-Y.,Lee, H.Y. Taylor Francis 2014 Ferroelectrics Vol.465 No.-

<P>CoFe2O4/Pt/Pb(Zr0.3Ti0.7)O-3 thin films were grown on Pt/Ti/SiO2/Si substrate in order to investigate the magnetoelectric properties of ferromagnetic/ferroelectric multilayer thin films. Thin Pt layer was introduced to prevent inter-diffusion between CoFe2O4 and Pb(Zr0.3Ti0.7)O-3 (PZT) layers. PZT thin film was grown directly on top of Pt substrate by utilizing sol-gel spin coating technique. In order to investigate the possible annealing effect on film microstructure and magnetoelectric properties, multilayer thin film stack was heat-treated at different temperatures ranging from 550 degrees C to 650 degrees C. The structural properties of the films were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Ferroelectric and ferromagnetic behaviors were analyzed by measuring polarization and magnetization - electric and magnetic field hysteresis. Magnetoelectric coefficients were calculated by measuring magnetoelectric voltages using magnetoelectric measurement system. Both the magnetoelectric properties and the coupling effect of CoFe2O4/Pt/PZT films on ferromagnetic and magnetoelectric properties are discussed as a function of heat-treatment temperature.</P>

Validation of egg yolk antibody based C-ELISA for avian influenza surveillance in breeder duck

Jeong, O.M.,Kim, M.C.,Kang, H.M.,Ha, G.W.,Oh, J.S.,Yoo, J.E.,Park, C.H.,Kwon, J.S.,Pack, M.R.,Kim, H.R.,Kim, Y.J.,Kwon, J.H.,Lee, Y.J. Elsevier Scientific Pub. Co 2010 Veterinary microbiology Vol.144 No.3

Active surveillance for avian influenza virus (AIV) has expanded from chicken to various poultry species including duck. To further effective antibody screening in laying breeder ducks, we validated the egg yolk antibody as alternative source to serum for AIV antibody. Sera and eggs were collected at weekly intervals after two types of AIV vaccination, H5N3 and H9N2. The antibody levels were determined by an agar gel immunodiffusion (AGID) test, haemagglutination inhibition (HI) test and the competitive enzyme-linked immunosorbent assay (C-ELISA). AGID test did not detect antibodies in egg yolk, and the agreement between AGID test and either HI test or C-ELISA in serum was slight and fair based on kappa statistics (kappa value (κ)@?0.19 in H5N3 group and κ@?0.37 in H9N2 groups). However, there was almost perfect agreement between HI test and C-ELISA (κ>0.9 in all group). The C-ELISA was as sensitive and specific as the HI test, and could be used as a pre-screening test for the detection of type A avian influenza virus antibody. Comparison was made between egg yolk and serum antibody titers by a regression analysis. A high correlation was observed between serum and yolk antibody titers (r=0.8762 for H5N3 and 0.8914 for H9N2 in HI test; r=1 for H5N3 and 0.9686 for H9N2 in ELISA test), although egg yolk antibodies were detected later and remained lower levels than serum antibodies. In field trials involving 54 duck flocks, the positive rate of egg yolk and serum samples showed agreement for the detection of AIV antibody. We concluded that as an alternative to serum, antibody monitoring of laying breeder duck using egg yolk with C-ELISA is feasible and is recommended.

Intravesical Instillation of c-MYC Inhibitor KSI-3716 Suppresses Orthotopic Bladder Tumor Growth

Jeong, K.C.,Kim, K.T.,Seo, H.H.,Shin, S.P.,Ahn, K.O.,Ji, M.J.,Park, W.S.,Kim, I.H.,Lee, S.J.,Seo, H.K. Williams and Wilkins Co 2014 The Journal of urology Vol.191 No.2

Purpose: c-MYC is a promising target for cancer therapy but its use is restricted by unwanted, devastating side effects. We explored whether intravesical instillation of the c-MYC inhibitor KSI-3716 could suppress tumor growth in murine orthotopic bladder xenografts. Materials and Methods: The small molecule KSI-3716, which blocks c-MYC/MAX binding to target gene promoters, was used as an intravesical chemotherapy agent. KSI-3716 action was assessed by electrophoretic mobility shift assay, chromatin immunoprecipitation, transcription reporter assay and quantitative reverse transcriptase-polymerase chain reaction. Inhibition of cell proliferation and its mechanism was monitored by cell cytotoxicity assay, EdU incorporation assay and flow cytometry. The in vivo efficacy of KSI-3716 was examined by noninvasive luminescence imaging and histological analysis after intravesical instillation of KSI-3716 in murine orthotopic bladder xenografts. Results: KSI-3716 blocked c-MYC/MAX from forming a complex with target gene promoters. c-MYC mediated transcriptional activity was inhibited by KSI-3716 at concentrations as low as 1 μM. The expression of c-MYC target genes, such as cyclin D2, CDK4 and hTERT, was markedly decreased. KSI-3716 exerted cytotoxic effects on bladder cancer cells by inducing cell cycle arrest and apoptosis. Intravesical instillation of KSI-3716 at a dose of 5 mg/kg significantly suppressed tumor growth with minimal systemic toxicity. Conclusions: The c-MYC inhibitor KSI-3716 could be developed as an effective intravesical chemotherapy agent for bladder cancer.

Effect of graphite reflector on activation of fusion breeding blanket

Lee, C.W.,Lee, Y.O.,Lee, D.W.,Cho, S.,Ahn, M.Y. North-Holland ; Elsevier Science Ltd 2016 Fusion engineering and design Vol.109 No.1

Korea has proposed a Helium-Cooled Ceramic Reflector (HCCR) breeding blanket concept relevant to fusion power plants. Here, graphite is used as a reflector material by reducing the amount of beryllium multiplier. In this paper, activity analysis was performed and the effect of graphite reflector in the view of activation was compared to the beryllium multiplier. As a result, it is expected that using the graphite reflector instead of the beryllium multiplier decreases total activity very effectively. But the graphite reflector produces C-14 about 17.2 times than the beryllium multiplier. Therefore, C-14 produced in the graphite reflector is expected as a significant nuclide in the view of radwaste management.

어육제품류의 기준규격 및 위해요소 중점관리방안에 관한 연구 : 어류 및 어육가공제품류의 위생적 품질지표로서의 부패성아민에 대하여 Putrefactive amines as a standpoint of sanitation of fish and fish products

이종옥,김명철,김인복,박혜경,김옥희,김연교,임성아,이근배,주현규 국립보건연구원 1994 국립보건원보 Vol.31 No.2

Complete Genome Sequence of Leuconostoc kimchii Strain C2, Isolated from Kimchi

Lee, S. H.,Jung, J. Y.,Lee, S. H.,Jeon, C. O. American Society for Microbiology 2011 Journal of Bacteriology Vol.193 No.19

탄소강의 온라인 열연 재질예측 시스템 개발

이재곤,권오준,이경종,강기봉,이필종,박윤순,노근기,민경준,이주동,유규천 대한금속재료학회(대한금속학회) 1992 대한금속·재료학회지 Vol.30 No.11

An on-line computer system was developed for prediction of tensile properties of C-Mn steels manufactured in the hot strip mill. To predict the final microstructure and properties in plain carbon steel hot coils, a mathematical model based on physical metallurgy was developed. Computer modelling was carried out to describe the microstrucal evolution during hot rolling and cooling and the interrelationships existing between microstructure and mechanical properties. The mathematical model consists of three sub-models : austenite conditioning model, transformation model and mechanical property model. The austenite conditioning model deals with recovery, recrystallization and grain growth which occur during hot rolling. The allotropic phase transformtaiton from austenite to ferrite, pearilte and bainite are described by the transformation model. The final mechanical properties are determined from the structure-property relationships established in the mechanical property model. An Avrami-type kinetic equation was used for mathematical representation of recrystallization and austenite/ferrite transformation. The structure-property relationship was formulated by combining the Hall-Petch equation with the mixture rule. In order to apply the model to the practical hot rolling process, an on-line computer system was installed at a hot strip mill. The on-line system consists of a high speed process computer and software packages. The predicted values of tensile strength from the system were in reasonable agreement with the measured ones when hot strips were processed under various rolling conditions.