• Journal of the Semiconductor & Display Technology
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• v.4 no.2 s.11
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• pp.11-14
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• 2005

In plasma processing reactors, it is common practice to control plasma density and ion bombardment energy by manipulating excitation voltage and frequency. In this paper, a dually excited capacitively coupled rf plasma reactor is self-consistently simulated with a three moment model. Effects of phase differences between primary and secondary voltage waves, simultaneously modulated at various combinations of commensurate frequencies, on plasma properties are investigated. The simulation results show that plasma potential and density as well as primary self-dc bias are nearly unaffected by the phase lag between the primary and the secondary voltage waves. The results also show that, with the secondary frequency substantially lower than the primary frequency, secondary self·do bias remains constant regardless of the phase lag. As the secondary frequency approaches to the primary frequency, however, the secondary self-dc bias becomes greatly altered by the phase lag, and so does the ion bombardment energy at the secondary electrode. These results demonstrate that ion bombardment energy can be more carefully controlled through plasma simulation.

• Journal of the Korean institute of surface engineering
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• v.32 no.3
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• pp.410-415
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• 1999

The adhesion strength of sputtered copper films to Inconel substrates has been studied using the scratch test. The effects of substrate treatments before deposition such as chemical or ion bombardment etching were investigated by means of a mean critical load derived from a Weibull-like statistical analysis. It was found that the mean critical load was very weak unless the amorphous layer produced by mechanical polishing on the substrate surface was eliminated. Chemical etching in a nitric-hydrochloric acid bath was shown to have practically no effect on the enhancement of the adhesion. In contrast, the addition in this bath of nickel and copper sulphates allowed removal of the amorphous layer and an increase in the values of the mean critical load. However, it was observed that excessive chemical etching could cancel out the mean critical load enhancement. The results obtained in the case of ion bombardment etching pretreatments could be far higher than those obtained with chemical etching. Moreover, for a sufficiently long period of ion bombardment etching, the adhesion strength was so high that it was impossible to observe evidence of an adhesion failure.

• Journal of Plant Biotechnology
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• v.44 no.1
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• pp.82-88
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• 2017

Transgenic lily plants have been obtained after particle bombardment, using PDS-1000/He system and scale explants of lilies, followed by PPT (D-L-phosphinothricin) selection. In this study, scales of the lily plants cv. 'red flame' were bombarded with a plasmid containing the bar gene as a selectable marker, and the AtSIZ gene as a gene of interest, showing salt tolerance and drought tolerance respectively, and both being driven by the CaMV 35S promoter. For optimization of a protocol, factors which optimized and showed a high transformation efficiency under following conditions, were considered: a bombardment pressure of 1100 psi, a target distance of 6 cm and $1.0{\mu}m$ of gold particle, and 24-h pre-culture and post-culture on MS medium containing 0.2 M sorbitol and 0.2 M mannitol as osmoticum agents. After bombardment, all the bombarded scales of lily were transferred to MS medium without selective agents, for a week. Subsequently, these bombarded scales were transferred to a selection MS medium containing 10 mg/l PPT, and incubated for a month for further selection, after which they were cultured for another 4-8 weeks with a 4-week subculture regime on the same selection medium. After transferring into hormone-free MS medium, the PPT-resistant scales with shoots were successfully rooted and regenerated into plantlets. PCR analysis revealed that the surviving putatively transformed plantlets indicated the presence of both the bar gene and the AtSIZ gene. In conclusion, when 100 scales of lily cv. Red flame are bombarded, this study produced approximately 17-18 transgenic plantlets with an optimized bombardment protocol. The protocol described here can contribute to the breeding program of lilies.

• Journal of Korean Society of Forest Science
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• v.86 no.3
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• pp.261-269
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• 1997

Excised immature ovules and calli derived from the stems of cottonwood were bombarded with microprojectiles carrying plasmid DNA containing CaMV-35S promoter and ${\beta}$-glucuronidase(GUS) gene. After bombarded, the expression of GUS gene was detected by the assay of 5-bromo-4-chloro-3-indolyl-${\beta}$-gluconide(X-gluc). Transient gene expression was measured by counting the number of distinct regions of GUS activity per explant. As major parameters, the number of shots and the period of exposure to X-gluc after the bombardment were investigated for detecting GUS gene expression. In this experiment, the percents of GUS gene expression showing spots were 56.8 from immature ovules and 75.9 from micro-calli of cottonwood species. Among the treatments, two consecutive shots and 48 hour exposure produced about $25.75{\pm}2.77$(per ovule), $11.43{\pm}1.22$(per mini petridish) spots, respectively, Microprojectile particle bombardment provides a useful method to assay transient expression in both types of explants. Furthermore, our results represent that the excised ovule and/or the calli might be stably transformed by the biolistics.

• Journal of Plant Biotechnology
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• v.47 no.1
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• pp.66-72
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• 2020

Alstroemeria plants were transformed by using an improved particle-gun-mediated transformation system. Friable embryogenic callus (FEC) induced from the leaves with axil tissues of Alstroemeria plant was used as the target tissue. Also, FEC was transformed with the bar gene was used as a selectable marker. In the case of plasmid pAHC25, 7.5% of the twice-bombarded FEC clumps showed blue foci, whereas the clumps with single bombardment showed only 2.3%. Additionally, a 90° rotation with double bombardment led to a higher frequency (6 times) of luciferase gene expression in PBL9780 than the control treatment. After 8 weeks of bombardment, more than 60 independent transgenic lines were obtained for pAHC25 and nearly 150 independent transgenic lines were obtained for PBL9780, all of which were resistant to PPT and demonstrated either GUS or luciferase activity. Regarding effect of osmotic treatment (0.2 M mannitol) with 7 different periods, the highest transient gene expression was obtained in 8 h before and 16 h after transformation in both pAHC25 and PBL9780. Compared with the control, at least three times more GUS foci and photons were observed in this treatment. With respect to different combinations of mannitol and sorbitol with 8 h before and 16 h after transformation, high numbers of transient and stable transgene expressions were observed in both 0.2 M mannitol and 0.2 M sorbitol used in the osmotic pre-culture. This combination showed the highest transformation efficiency in both pAHC25 (8.5%) and PBL9780 (14.5%). In the control treatment, only 10% of the FEC clumps produced somatic embryos. However, by using 0.2 M mannitol and 0.2 M sorbitol, the frequency of somatic embryos increased to 36.5% (pAHC25) and 22.9% (PBL9780). Of the somatic embryos produced, at least 60% germinated. Approximately 100 somatic embryos from these 210 independent transgenic lines from 2 plasmids developed into shoots, which were then transferred to the greenhouse. PCR analysis confirmed the presence of the bar gene. This is the report on the production of transgenic Alstroemeria plants by using particle bombardment with a high efficiency, thereby providing a new alternative for the transferring of gene of interests in Alstroemeria in the breeding program in the future.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.217-217
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• 2016

The amorphous InGaZnO (a-IGZO) is widely accepted as a promising channel material for thin-film transistor (TFT) applications owing to their outstanding electrical properties [1, 2]. However, a-IGZO TFTs have still suffered from their bias instability with illumination [1-4]. Up to now, many researchers have studied the sub-gap density of states (DOS) as the root cause of instability. It is well known that defect states can influence on the performances and stabilities of a-IGZO TFTs. The defects states should be closely related with the deposition condition, including sputtering power, and pressure. Nevertheless, it has not been reported how these defects are created during conventional RF magnetron sputtering. In general, during conventional RF magnetron sputtering process, negative oxygen ions (NOIs) can be generated by electron attachment in oxygen atom near target surface and then accelerated up to few hundreds eV by a self-bias; at this time, the high energy bombardment of NOIs induce defects in oxide thin films. Recently, we have reported that the properties of IGZO thin films are strongly related with effects of NOIs which are generated during the sputtering process [5]. From our previous results, the electrical characteristics and the chemical bonding states of a-IGZO thin films were depended with the bombardment energy of NOIs. And also, we suggest that the deep sub-gap states in a-IGZO as well as thin film properties would be influenced by the bombardment of high energetic NOIs during the sputtering process.In this study, we will introduce our novel technology named as Magnetic Field Shielded Sputtering (MFSS) process to prevent the NOIs bombardment effects and present how much to be improved the properties of a-IGZO thin film by this new deposition method. We deposited a-IGZO thin films by MFSS on SiO2/p-Si and glass substrate at various process conditions, after which we investigated the morphology, optical and electrical properties of the a-IGZO thin films.

• BMB Reports
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• v.39 no.1
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• pp.61-67
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• 2006

Molecular co-suppression phenomena are important to consider in transgene experiments. Embryogenic cells were obtained from immature cotyledons and engineered with two different gene constructs (pHV and pHVS) through particle bombardment. Both constructs contain a gene conferring resistance to hygromycin (hpt) as a selective marker and a modified glycinin (11S globulin) gene (V3-1) as a target. sGFP(S65T) as a reporter gene was, however, inserted into the flanking region of the V3-1 gene (pHVS). Fluorescence microscopic screening after the selection of hygromycin, identified clearly the expression of sGFP(S65T) in the transformed soybean embryos bombarded with the pHVS construct. Stable integration of the transgenes was confirmed by polymerase chain reaction (PCR) and Southern blot analysis. Seeds of transgenic plants obtained from the pHV construct frequently lacked an accumulation of endogenous glycinin, which is encoded by homologous genes to the target gene V3-1. Most of the transgenic plants expressing sGFP(S65T) showed highly accumulation of glycinin. The expression of sGFP(S65T) and V3-1 inherits into the next generations. sGFP(S65T) as a reporter gene may be useful to increase the transformation efficiency of transgenic soybean with avoiding gene co-suppression.

• Journal of Plant Biotechnology
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• v.47 no.2
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• pp.164-171
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• 2020

Transgenic Alstroemeria plants resistant to Alstroemeria mosaic virus (AlMV) were generated through RNA-mediated resistance. To this end, the friable embryogenic callus (FEC) of Alstroemeria was induced from the leaf axil tissue and transformed with a DNA fragment containing the coat protein gene and 3'-nontranslated region of AlMV through an improved particle bombardment system. The bar gene was used as a selection marker. More than 300 independent transgenic FEC lines were obtained. Among these, 155 lines resistant to phosphinothricin (PPT) were selected under low stringent conditions. After increasing the stringency of PPT selection, 44 transgenic lines remained, and 710 somatic embryos from these lines germinated and developed into shoots. These transgenic shoots were then transferred to the greenhouse and challenged with AlMV. In total, 25 of the 44 lines showed some degree of resistance. PCR analysis confirmed the presence of the viral sequence. Virus resistance was observed at various levels. Establishment of an efficient transformation system for Alstroemeria will allow inserting transgenes into this plant to confer resistance to viral and fungal pathogens. Accordingly, this is the first report on the production of a transgenic virus-resistant Alstroemeria and lays the foundation for alternative management of viral diseases in this plant.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2002.05a
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• pp.46-46
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• 2002

It is well known that thin film growth and surface morphology can be substantially modified by ion-bombardment during the deposition. This is particularly important in case of thin-film deposition at low temperatures where the film growth occurs under highly nonequilibrium conditions. An attractive way to promote crystalline growth and surface morphology is deposition of additional energy in to the surface of the growing film by bombardment with hyperthermal particles. We were deposited crystalline Ti and TiN thin films on Si substrate by magnetron sputtering method with grid. Its thin films were highly smoothed and dense as increasing grid bias. In order explore the benefits of a bombardment of the growing film with high energetic particles. Ti and TiN films were deposited on Si substrates by an unbalanced magnetron sputter source with attached grid assembly for energetic ion extraction. Also, we have studied the variation of the plasma states by Langmuir probe and Optical Emission Spectroscopy (OES). The epitaxial orientation. microstructual characteristics. electrical and surface properties of the films were analyzed by XRD. SEM. Four point probe and AFM.

• Bulletin of the Korean Chemical Society
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• v.28 no.8
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• pp.1341-1345
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• 2007

The surface chemistry of D2O dosed Zircaloy-4 (Zry-4) surface followed by Ar-ion bombardment and annealing was studied by means of X-ray photoelectron spectroscopy (XPS) and Ultraviolet photoelectron spectroscopy (UPS). In the XPS study, Ar-ion bombardment caused decrease of the oxygen on the surface region of Zry-4 and therefore led to change the oxidation states of the zirconium from oxide to metallic form. In addition, oxidation states of zirconium were changed to lower oxidation states of zirconium due to depopulation of oxygen on the surface region by annealing. Up to about 787 K, the bulk oxygen diffused out to the subsurface region and after this temperature, the oxygen on the surface of Zry-4 was depopulated. UPS study showed that the valence band spectrum of the D2O exposed Zry-4 exhibited a dominant peak at around 13 eV and no clear Fermi edge was detected. After stepwise Ar+ sputtering processes, the decrease of the oxygen on the surface of Zry-4 led to suppress the dominant peak around 13 eV, the peak around 9 eV and develop a new peak of the metallic Zr 4d state (20.5-21.0 eV) at the Fermi level.