• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.3
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• pp.268-272
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• 2007

A fully integrable InP/InGaAs HPT with an ITO emitter contact was first fabricated by employing a $SiO_2$ passivation layer. The electrical and the optical characteristics of the HPT with a passivation layer were measured and compared with those of the HPT without a passivation layer. The only noticeable difference was the increased emitter series resistance of the HPT with a passivation layer. AES analysis was performed to explain the reason of the increased emitter series resistance. Results show that PECVD $SiO_2$ deposition and annealing processes cause the diffusion of oxygen to the interface and the depletion of tin at the interface, which may be responsible for the increase of the series resistance.

• Journal of the Korean institute of surface engineering
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• v.29 no.6
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• pp.607-614
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• 1996

Yttrium(Y) coating was incorporated by ion-plating method either directly on the TiAl substrate or after pack aluminizing on TiAl to improve the oxidation resistance of TiAl alloy. After Y-coating, heat treatment at low oxygen partial pressure was carried out. Performance of various coating was evaluated by isothermal and cyclic oxidation tests. A simple Y-coating without pack aluminizing can give a detrimental effect on the. oxidation resistance of TiAl alloy, because it enhances formation of $TiO_2$. On the other hand, a composite coating of aluminide-yttrium has shown excellent oxidation resistance. A continuous protective $Al_2O_3$ scale is formed on the aluminized TiAl, and Y-coating improves $Al_2O_3$ scale adherence and substantially prevents depletion of Al in the aluminide-coating layer.

• Journal of Pharmaceutical Investigation
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• v.37 no.5
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• pp.287-290
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• 2007

Intrinsic or acquired resistance to chemotherapeutic drugs is one of the major obstacles to effective cancer treatment. Hypoxia is widespread in solid tumors as a consequence of decreased blood flow in the tumor-derived neovasculature. The recent finding of a link between hypoxia and chemoresistance prompted us to investigate whether hypoxia induces doxorubicin resistance in human MCF-7 breast cancer cells. Low oxygen concentration decreased the doxorubicin sensitivity in MCF-7 cells. The expression of p-glycoprotein, a major MDR-related transporter, and those of apoptosis-related proteins (anti-apoptotic Bcl-2, Bcl-XL and pro-apoptotic Bax) were not altered by hypoxia in MCF-7 cells. Intracellular uptake of doxorubicin was significantly decreased under hypoxic conditions. Decreased cellular uptake of doxorubicin under hypoxia may contribute to causing doxorubicin resistance in these cells. The use of agents that can modulate the doxorubicin uptake for adjuvant therapy may contribute to improving the therapeutic efficacy of doxorubicin in breast cancer patients.

• Corrosion Science and Technology
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• v.7 no.4
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• pp.233-236
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• 2008

Halide-activated pack cementation was utilized to deposit B-doped silicide coating. The pack powders were consisted of $3Wt.c/oNH_4Cl$, 7Wt.c/oSi, $90Wt.c/oAl_2O_3+TiB_2$. B-doped silicide coating was consisted of two layers, an outer layer of $NbSi_2$ and an inner layer of $Nb_5Si_3$. Isothermal oxidation resistance of B-doped silicide coating was tested at $1250^{\circ}C$ in static air. B-doped silicide coating had excellent oxidation resistance, because continuous $SiO_2$ scale which serves as obstacle of oxygen diffusion was formed after oxidation.

• Journal of Environmental Impact Assessment
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• v.12 no.1
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• pp.35-44
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• 2003

Bacterial activities of dam reservoir sediments were assessed using the methods of viable counts, ATP contents, dehydrogenase activity, and oxygen consumption. Viable heterotrophs in collected sediments were observed in the range of $10^6{\sim}10^{10}$ CFU/g dry wt. sediment. All assessed methods showed high activities in sediment samples collected from near dam site. In addition, bacteria increase in sediments amended with cellulose, starch, lipid, and protein compounds. Various ranges of antibiotics and heavy metals resistance bacteria were also detected, especially, 10~100 times less numbers of Cd resistance bacteria were observed compared with those of Pb and Cr. In general, antibiotics resistance groups were in the range of $10^{-1}{\sim}10^{-6}$ times of control.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1795-1796
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• 1999

ITO thin films have been deposited on PET substrate by reactive dc magnetron sputtering without substrate heater and post heat treatment. The electrical and optical properties of as-deposited films are dominated by oxygen gas ratio. As the experimental results, the excellent ITO films are prepared on PET substrate at the operating conditions as follows: operating pressure of 5 mTorr, target-substrate distance of 4.5 cm, dc power of $20{\sim}30W$, and oxygen gas ratio of 10 %. The optical transmittance is above 80 % at 550 nm, and the sheet resistance and resistivity of films are $24{\Omega}$/square and $1.5{\times}10^{-3}{\Omega}cm$, respectively.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.1
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• pp.8-12
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• 2005

Indium tin oxide(ITO) surface treated by Oxygen plasma has been in situ analyzed using XPS(X-ray Photoelectron Spectroscopy) and EDS(Energy Dispersive Spectroscopy), to investigate the relations between the properties of the ITO surface and the properties of OLED(Organic Light Emitting Diode). We measured electrical resistivity using Four-Point-Probe and calculated sheet resistance, and ITO surface roughness was measured by AFM(Atomic Force Microscope). We fabricated OLED using substrate that was treated optimum ITO surface. The plasma treatment of the ITO surface lowered the operating voltage of the OLED. We have obtained an improvement of luminance and decrease of turn-on voltage.

• The Korean Journal of Ecology
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• v.17 no.1
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• pp.91-100
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• 1994

Although the types of stress are various, environmental stresses generally increase the amounts of reactive oxygen species in plants. These reactive oxygen species stimulate stress-ethylene synthesis and accelerate senescence of plants. However, when stress-ethylene synthesis is suppressed through antioxidative enzymes and antioxidants, the resistance of plants against stress could be induced by limited production of ethylene.

• Proceedings of the KOSOMBE Conference
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• v.1998 no.11
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• pp.237-238
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• 1998

The kinetics of sulfite oxidation must be fast and the concentration of sulfite must be low to emulate oxygen uptake by blood. The kinetics were studied yielding a first order rate constant in sulfile, zero order in oxygen. Limitations of the technique were evaluated using the experimental rate constant and an adaptation of Lightfoot's approximation, while the reaction of hemoglobin is reversible and essentially instantaneous, that for sulfite is irreversible and finite. Thus if the approach to saturations not monotonic or if the mass transfer resistance is significantly lowered, e. g. when blood film thicknesses are thinner than a few hundred microns, deviations may occur.

• Journal of the Korean institute of surface engineering
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• v.32 no.6
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• pp.671-676
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• 1999

ITO (indium tin oxide) thin films on PET (polyethylene terephthalate) substrate have been deposited by a dc reactive magnetron sputtering without heat treatments such as substrate heater and post heat treatment. Each sputtering parameter during the sputtering deposition is an important factor for the high quality of ITO thin films deposited on polymeric substrate. Particularly, the material, electrical and optical properties of as-deposited ITO oxide films are dominated by the ratio of oxygen partial pressure. As the experimental results, the excellent ITO films are prepared on PET substrate at the operating conditions as follows : operating pressure of 5 mTorr, target-substrate distance of 45mm, do power of 20~30W, and oxygen gas ratio of 10%. The optical transmittance is above 80% at 550 nm, and the sheet resistance and resistivity of films are 24 Ω/square and $1.5\times$10$^{-3}$ Ωcm, respectively.