• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.86.1-86.1
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• 2015

As the feature size of Si-based semiconductor shrinks to nanometer scale, we are facing to the problems such as short channel effect and leakage current. One of the solutions to cope with those issues is to bring III-V compound semiconductors to the semiconductor structures, because III-V compound semiconductors have much higher carrier mobility than Si. However, introduction of III-V semiconductors to the current Si-based manufacturing process requires great challenge in the development of process integration, since they exhibit totally different physical and chemical properties from Si. For example, epitaxial growth, surface preparation and wet etching of III-V semiconductors have to be optimized for production. In addition, oxidation mechanisms of III-V semiconductors should be elucidated and re-growth of native oxide should be controlled. In this study, surface preparation methods of various III-V compound semiconductors such as GaAs, InAs, and GaSb are introduced in terms of i) how their surfaces are modified after different chemical treatments, ii) how they will be re-oxidized after chemical treatments, and iii) is there any effect of surface orientation on the surface preparation and re-growth of oxide. Surface termination and behaviors on those semiconductors were observed by MIR-FTIR, XPS, ellipsometer, and contact angle measurements. In addition, photoresist stripping process on III-V semiconductor is also studied, because there is a chance that a conventional photoresist stripping process can attack III-V semiconductor surfaces. Based on the Hansen theory various organic solvents such as 1-methyl-2-pyrrolydone, dimethyl sulfoxide, benzyl alcohol, and propylene carbonate, were selected to remove photoresists with and without ion implantation. Although SPM and DIO3 caused etching and/or surface roughening of III-V semiconductor surface, organic solvents could remove I-line photoresist without attack of III-V semiconductor surface. The behavior of photoresist removal depends on the solvent temperature and ion implantation dose.

• Microbiology and Biotechnology Letters
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• v.42 no.3
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• pp.238-248
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• 2014

The metalloid arsenic (Z = 33) is considered to be a significant potential threat to human health due to its ubiquity and toxicity, even in rural regions. In this study a rural region contaminated with arsenic, located at longitude $85^{\circ}$ 32'E and latitude $25^{\circ}$ 11'N, was initially examined. Arsenic tolerant bacteria from the rhizosphere of Amaranthas viridis were found and identified as Bacillus licheniformis through 16S rRNA gene sequencing. The potential for the uptake and removal of arsenic at 3, 6 and 9 mM [As(V)], and 2, 4 and 6 mM [As(III)], and for the reduction of the above concentrations of As(V) to As(III) by the Bacillus licheniformis were then assessed. The minimal inhibitory concentrations (MIC) for As(V) and As(III) was determined to be 10 and 7 mM, respectively. At 3 mM 100% As(V) was uptaken by the bacteria with the liberation of 42% As(III) into the medium, whereas at 6 mM As(V), 76% AS(V) was removed from the media and 56% was reduced to As(III). At 2 mM As(III), the bacteria consumed 100%, whereas at 6 mM, the As(III) consumption was only 40%. The role of pH was significant for the speciation, availability and toxicity of the arsenic, which was measured as the variation in growth, uptake and content of cell protein. Both As(V) and As(III) were most toxic at around a neutral pH, whereas both acidic and basic pH favored growth, but at variable levels. Contrary to many reports, the total cell protein content in the bacteria was enhanced by both As(V) and As(III) stress.

• Journal of the Korean Chemical Society
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• v.18 no.4
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• pp.259-266
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• 1974

Isotopic experiments using $H_2O^{18}$ on the oxidation of V(III) in acid perchlorate by molecular oxygen were performed in the range pH 1.0 to 3.0. At pH < 2, where a rate equation of the form TEX>$ -\frac{d[V(III)]}{dt}=k_1\frac{[O_2][V(III)]}{[H^+]}$ is adequate, the tracer study clearly indicated that all the product vanadyl ion's ($VO^{2+}$) oxygen originated from the molecular oxygen. At pH > ~2, where a different rate expression of the form $-\frac{d[V(III)]}{dt}=K_2\frac{[O_2][V(III)]^2}{[Ht]^2}$is required, the isotopic experiment showed that half the vanadyl oxygen originated from the molecular oxygen. Considering the results of the isotopic study, a mechanism for the V(Ⅲ)-O2 reaction at pH < ~2, may be suggested as follows: The tracer results at pH > ~2 imply that the rate determining step may be $$ V_2(OH)_2^{4+} + O_2 \rightarrow 2VO^{2+} + H_2O_2$$ followed by $$V_2(OH)_2^{4+} + H_2O_2 \rightarrow 2VO^{2+} + 2H_2O$$ after establishing the equilibria V^{3+} + H_2O \leftrightarrow VOH^{2+} + H^+, and 2VOH^{2+}\leftrightarrow V_2(OH)_2^{4+}$$

• Journal of Microbiology and Biotechnology
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• v.14 no.5
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• pp.891-900
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• 2004

UDP-N-Acetylglucosamine(GlcNAc):$\beta$1,4-D-mannoside$\beta$-l ,4N-acetylglucosaminyltransferase-III (GnT-III) and UDP-N-GlcNAc:$\alpha$-6-D-mannosid$\beta$-1,6N-acetylglucosaminyltransferase-V(GnT - V) activities were determined in human hepatoma cell lines and metastatic colon cancer cells, and their activities were compared with those of normal liver cells and fetal hepatocytes. GnT-III activities were higher than those of GnT-V in hepatic carcinoma cells. When the two enzyme activities were assayed in highly metastatic colon cancer cells, GnT - V activities were much higher than those of GnT-III. When GlcN, GlcN-biant-PA and UDP-GlcNAc were used as substrates, the enzymes displayed different kinetic properties between hepatic and colon cancer cells, depending on their metastatic potentials. Normal cells of two origins had characteristically very low levels of GnT-III and -V activities, whereas hepatoma and colon cancer cells contained high levels of activities. These data were supported by RT-PCR and Northern blot analyses, showing that the expression of GnT-III and -V mRNAs were increased in proportion to the enzymatic activities. The increased GnT-III, md -V activities were also correlated with increased glycosylation of the cellular glycoproteins in hepatoma and colon cancer cells, as examined by lectin blotting analysis by using wheat germ glutinin (WGA), erythroagglutinating phytohemagglutinin (E-PHA), leukoagglutinating phytohemagglutinin (L-PHA), and concanavalin A (Con A). Treatment with retinoic acid, a differentiation agent, resulted in decreases of both GnT-III and -V activities of HepG2 and HepG3 cells. In colon carcinoma cells, however, treatment with retinoic acid resulted in a reduction of GnT-V activity, but not with GnT-III activity. Although the mechanism underlying the induction of these mzymes is unclear, oligosaccharides in many glycoproteins have been observed of cancer cells.

• Electronics and Telecommunications Trends
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• v.36 no.3
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• pp.23-33
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• 2021

Two main technologies of III-V/Si laser diode for optical communication, direct epitaxial growth, and wafer bonding were studied. Until now, the wafer bonding has been vigorously studied and seems promising for the ideal III-V/Si laser. However, the wafer bonding process is still complicated and has a limit of mass production. The development of a concise and innovative integration method for silicon photonics is urgent. In the future, the demand for high-speed data processing and energy saving, as well as ultra-high density integration, will increase. Therefore, the study for the hetero-junction, which is that the III-V compound semiconductor is directly grown on Si semiconductor can overcome the current limitations and may be the goal for the ideal III-V/Si laser diode.

• Analytical Science and Technology
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• v.13 no.2
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• pp.189-193
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• 2000

Arsenic (III) and arsenic (V) in disused mine tailing samples have been determined simutaneuously by hydride generation inductively coupled plasma atomic emission spectrometry (HG-ICP-AES). Total arsenic was determined using 2% $NaBH_4$ and 6 M HCl after prereduction of As(V) to As(III) with) 1M KI. Arsenic (III) was determined selectively using citrate/citric acid buffer with range of pH 5-6, it was determined by HG-ICP-AES. Arsenic (V) can be evaluated by the differences. According to the results, arsenic (V) was over 90% among the total arsenic extracted from disused mine tailing samples.

• Biotechnology and Bioprocess Engineering:BBE
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• v.9 no.1
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• pp.47-51
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• 2004

Ceramide III was prepared by the cultivation of Saccharomyces cerevisiae. Ceramide III was partitioned from the cell extracts by solvent extraction and analyzed by Normal Phase High Performance Liquid Chromatography (NP-HPLC) using Evaporative Light Scattering Detector (ELSD). We experimentally determined the mobile phase composition to separate ceramide III with NP-HPLC. Three binary mobile phases of n-hexane/ethanol, n-hexane/lsoprophyl Alcohol(IPA) and n-hexane/n-butanol and one ternary mobile phase of n-hexane/IPA/methanol were demonstrated. For the binary mobile phase of n-hexane/ethanol, the first mobile phase composition, 95/5(v/v), was step-increased to 72/23(v/v) at 3 min. In the binary mobile phase, the retention time of ceramide III was 7.87min, while it was 4.11 min respectively in the ternary system, where the mobile phase composition of n-hexane/IPA/methanol, 85/7/8(v/v/v), was step-increased to 75/10/15(v/v/v) at 3 min. However, in the ternary mobile phase, the more peak area of ceramide III was observed.

• Journal of Soil and Groundwater Environment
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• v.13 no.1
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• pp.52-59
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• 2008

Adsorption is a major process causing the accumulation of arsenic onto soil. Therefore, further understanding of the adsorption/desorption characteristics of arsenic species on soil is essential for predicting their fate and preparing appropriate remediation strategy to remove arsenic from soil. In this study, the column adsorption/desorption experiment has been performed with As(III) and As(V) on soil. Experiment with As(III) was conducted under reducing condition, whereas that with As(V) was under oxidizing condition. Most of As(III) was remained on the oxidation state during the experiment. The results showed that the adsorption/desorption rate of As(III) was higher than that of As(V). Adsorption and desorption of arsenic species were not completely reversible in the column experiment. It was also found that As(V) in the column experiment was adsorbed more rapidly on soil than in the batch experiment.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.31-31
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• 2000

In this paper, Ive design and test the V/F converter for KSR-III INS using commertial INC, VFC110, AD652. The test result shows that performance of AD652 is better than that of VFC110. Through the calibration of V/F converter, we show that the designed V/F converter has a good performance and is usable for KSR-III.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.7
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• pp.731-737
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• 2006

Four well-characterized soils collected from A- and B-horizon in the Department of Energy Oak Ridge Reservation in USA, mainly distributed with Inceptisol(Inc) and Ultisol(Ult) soils, were used in this work. The bioaccessibility of arsenic as well as oxidation phenomena of As(III) was investigated with soils spiked with As(III) and As(V) using a physiologically based extraction test(PBET) at pH 1.5 and 1:100 soil to solution ratio. Also effect of aging time on the bioaccessibility of arsenic was investigated over the 6 months. After 48 hours(fresh) contacting As(V) solution with soils, all soils rapidly and strongly sequestrated As(V), especially Ult-B. However, little sequestration was observed after 3-months. When As(III) was spiked on the same soils, a great portion of As(III) was oxidized to As(V) after 48 hrs, especially Inc-A and Ult-A soils, which is strongly related with Mn content in soils. By using As(III)-spiked soils, much reduced bioaccessibility as total arsenic was observed from Inc-B and Ult-B soils over the 6 months aging time compared to that from Inc-A and Ult-A soils. This result can be explained by the continuous sequestration of As(V), produced from oxidation of As(III), onto Inc-B and Ult-B soils having much amount of iron. The trend of As(III) sequestration over six months aging time was quite similar with that of As(V) sequestration.