• Transactions on Electrical and Electronic Materials
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• v.9 no.5
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• pp.202-205
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• 2008

We have studied the liquid crystal (LC) orientation behavior on the organic hybrid overcoat layer with ion beam irradiation. Excellent LC alignments of the nematic liquid crystal (NLC) on the ion beam irradiated organic hybrid overcoat layers were observed in various intensities above 600 eV. Pretilt angles of the NLC on the organic hybrid overcoat layers for all ion beam energy intensities were observed from 0.2 to 0.5 degrees. Also, we used the atomic force microscopy (AFM) images for measuring the roughness of the organic hybrid overcoat layers with ion beam irradiation before and after. The surface of organic hybrid overcoat layers was leveled off by the ion beam irradiation. Finally, a good LC alignment thermal stability on the organic hybrid overcoat layer with ion beam irradiation can be achieved.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.5
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• pp.382-386
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• 2019

The alignment characteristics of liquid crystal (LC) molecules on a solution-derived lanthanum zinc oxide (LZO) film under ion-beam irradiation were demonstrated. Using the solution process, an LZO film was fabricated on the glass substrate and cured at $100^{\circ}C$. Afterwards, ion-beam irradiation was performed following the LC alignment method. Using this film, an LC cell was fabricated and the characteristics of the LC alignment were verified. Cross polarizing microscopy and the crystal rotation method were used to investigate the alignment state of the LC molecules on the LZO films. Furthermore, field emission scanning electron microscopy and X-ray photoelectron spectroscopy were used to explore the effect of the ion-beam irradiation on the LZO film. Through these, it was confirmed that the ion-beam irradiation induced surface modification, which demonstrated anisotropic physical and chemical surface characteristics. Due to this, uniform LC alignment was achieved. Finally, the residual DC and anchoring energy of the LC cell based on the LZO films were measured using a capacitance-voltage curve.

• Korean Journal of Plant Tissue Culture
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• v.27 no.2
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• pp.109-115
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• 2000

Effects of the heavy-ion ($^{14}$ N or $^{20}$ Ne) beam irradiation on the response of anthers, growth of calli, germination of seeds, and the early growth after the germination of tobacco (Nicotiana tabacum L. cv. BY-4) were investigated. Anthers precultured for 10 days before the irradiation became brown without callus or shoot induction over 20 Gy of $^{14}$ N and $^{20}$ Ne ion beam irradiation. Relative growth rate of the cultured calli was reduced by the irradiation and became brown significantly 2 weeks after the $^{14}$ N and $^{20}$ Ne ion beam irradiation over 50 Gy. The increased intensity of the heavy-ion ($^{14}$ N, $^{20}$ Ne) beam irradiation resulted in the delay of seed germination and the inhibition of the early growth both in water-treated and non-treated seeds before the irradiation. In addition, the heavy-ion beam irradiation to the imbibed seeds inhibited seed germination more than that to the non-imbibed seeds. The screening approach of non-imbibed seeds with heavy-ion beam irradiation using in vitro culture system was more useful than the filter-paper germination method in investigating the characteristics of heavy-ion beam-irradiated seed population and the screening of morphological variants at the early stage of the plant growth.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.98-98
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• 2010

Ion beam irradiation has been extensively used for surface modification of polymers, glassy metals and amorphous and crystalline materials at micron and submicron scales. The surface structures created by exposure to an ion beam range from dots, steps and one-dimensional straight wrinkles to highly complex hierarchical undulations and ripples. In general, the morphology of these nanoscale features can be selected by controlling the ion beam parameters (e.g. fluence and acceleration voltage), making ion beam irradiation a promising method for the surface engineering of materials. In the work, we presented that ion beam irradiation results in creation of a peculiar nanoscale dimple-like structure on the surface of polyimide - a common polymer in electronics, large scale structures, automobile industry, and biomedical applications. The role of broad Ar ion beam on the morphology of the structural features was investigated and insights into the mechanisms of formation of these nanoscale features were provided. Moreover, a systematic experimental study was performed to quantify the role of ion beam treatment time, and thus the morphology, on the coefficient of friction of polyimide surfaces covered by nanostructure using a tribo-experiment. Nano-indentation experiment were performed on the ion beam treated surfaces which shows that the hardness as well as the elastic modulus of the polyimide surface increased with increase of Ar ion beam treatment time. The increased of hardness of polyimide have been explained in terms of surface structure as well as morphology changes induced by Ar ion beam treatment.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.330-330
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• 2008

It is widely investigated to liquid crystal (LC) alignment using non-contact alignment method such as ion-beam (IB) irradiation, UV alignment, and oblique deposition. Because conventional rubbing method has some drawbacks. These include defects from dust and electrostatic charges and rubbing scratch during rubbing process. In addition, rubbing method needs additional process to remove these defects. Therefore rubbing-free methods like ion-beam irradiation are strongly required. We studied LC alignment effect on poly imide surface by IB irradiation and electro-optical (EO) characteristics of twisted nematic liquid crystal display (TN-LCD). In this experiment, a good uniform alignment of the nematic liquid crystal (NLC) with the ion-beam exposure on the polyimide (PI) (SE-150 from Nissan Chemical) surface was observed. We also achieved low pretilt angle as a function of ion-beam irradiation intensity. In addition, it can be obtained the good EO properties of the IB-aligned TN-LCD on PI surface. Some other experiments results and discussion will be included in the poster.

• Journal of Periodontal and Implant Science
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• v.28 no.2
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• pp.281-291
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• 1998

Chitosan is a biodegradable and non-toxic material with a molecular weight of 800-1,500Kd which can be obtained in various forms with extraordinary chemical structures and biological characteristics of which enables it to be used in many fields as a biomaterial. Ion irradiation is a useful tool to modify chemical structures and physical properties of high molecular weight polymers. The basic hypothesis of this study is that when surface properties of chitosan in a sponge form are modified with ion beam-irradiation and cell adhesion properties of chitosan would improve and thereby increase the regenerative ability of the damaged bone. The purpose of this study was to illuminate the changes in the cytocompatibility of chitosan sponges after ion beam-irradiation as a preliminary research. Argon($Ar^+$) ions were irradiated at doses of $5{\times}10^{13}$, $5{\times}10^{15}$ at 35 keV on surfaces of each sponges. Cell adhesion and activity of alkaline phosphatases were studied using rat fetal osteoblasts. The results of this study show hat ion beam-irradiation at optimal doses($5{\times}10^^{13}\;Ar^+\;ion/cm^2$) is a useful method to improve cytocompatibility without sacrificing cell viability and any changing cell phenotypes. These results show that ion beam-irradiated chitosan sponges can be further applied as carriers in tissue engineering and as bone filling materials.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.839-844
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• 2002

This letter focuses on the liquid crystal alignment characteristics according to the properties of hydrogenated amorphous carbon(a-C:H) thin film deposited by RPECVD(Remote Plasma Enhanced Chemical Vapor Deposition) method using $C_2H_2$ and He gases. The properties of the deposited thin films were controlled by the ion beam irradiation time and ion beam energy. The results show that not ion beam energy but ion beam irradiation time plays an important role in the properties of a-G:H thin films. As the ion beam irradiation time increases, not only the sp2 concentration in a-G:H thin films but also liquid crystal pretilt angle was varied.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.03b
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• pp.15-16
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• 2010

We used Brewster's Law to examine the mechanism of liquid crystal (LC) alignment on an organic insulation layer when subjected to ion-beam irradiation. Brewster's Law implies that the maximum rate polarized rayon a slanted insulation layers on the substrate and it illustrates the dependence of polarization and themechanical structure on the ion beam irradiation process. The pretilt angle of nematic LCs on the organic insulation surface was about $1.13^{\circ}$ for an ion beam exposure of $45^{\circ}$ for 1 minute at 1800eV. This shows the dependence of LC alignment on the polarization ratio in a slanted organic insulation layer. We also discussed the electro-optical characteristic of twisted nematic (TN) LCD using ion beam irradiation on organic overcoat layer.

• Journal of the Korean Vacuum Society
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• v.4 no.S2
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• pp.95-99
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• 1995

keV ion beam irradiatin for surface modification and thin film growth have been discussed. keV ion beam irradiation in reactive gas environment has been developed for improving wettability of polymer, and for enhancing adhesion to metal film, and adventages of the method have been reviewed. An epitaxial Cu film on Si(100) substrate has been grown by ionized cluster beam and changes of crystallinity and surface roughness have been discussed. Stoichiometric $SnO_2$ films on Si(100) and glass have been grown by a hybrid ion beam Deposition(2 metal ion sources+1 gas ion source), and nonstoichiometric $SnO_2$ films are controlled by various deposition conditions in the HIB. Surface modification for polymer by kev ion irradiation have been developed. Wetting angle of water to PC has been changed from 68 degree to 49 degree with $Ar^+$ irradiation and to 8 degree with $Ar^+$ irradiation and the oxygen environment. Change of surface phenomena in a keV ion beam and characteristics of the grown films are suggested.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.04a
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• pp.43-43
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• 2008

Recently, it is widely studied to liquid crystal (LC) alignment using ion-beam exposure. Because conventional rubbing method has some problems such as defects from dust and electrostatic charges and rubbing scratch during rubbing process. Moreover rubbing method needs cleaning process to remove these defects. Therefore rubbing-free techniques like ion-beam method are strongly required. We studied LC alignment by controlling ion-beam irradiation angles and electro-optical (EO) characteristics of twisted nematic LC on the polyimide surface. In this experiment, a good uniform alignment of the nematic liquid crystal (NLC) with the ion-beam exposure on the polyimide (PI) surface was observed. We also achieved low pretilt angle as function of ion-beam irradiation angles. X-ray photoelectron spectroscopic (XPS) analysis provided chemical evidence for LC alignment by controlling ion-beam irradiation angles. In addition, it can be achieved the good EO properties of the ion-beam-aligned twisted nematic liquid crystal display (TN-LCD) on PI surface. Some other experiments results and discussion will be included in the presentation.