• Transactions on Electrical and Electronic Materials
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• v.9 no.6
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• pp.243-246
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• 2008

We have studied the liquid crystal (LC) alignment, the pretilt angle generation, and the annealing behavior for a nematic liquid crystal (NLC) on the homogeneous polyimide (PI) surfaces by using the rubbing method and the ion beam (IB) method. An excellent LC alignment of the NLC on the PI surface with rubbing and IB irradiation were observed. The pretilt angle of NLC on the homogeneous PI surface for the rubbing method is decreased from $4.5^{\circ}$ to $3.5^{\circ}$ as rubbing time is increased, that of the for the IB irradiation method is decreased from $0.5^{\circ}$ to $0.1^{\circ}$ as the time of IB irradiation is increased. After the annealing, the pretilt angles of the rubbed PI surfaces increased up to $4^{\circ}$, these of the IB irradiated PI surfaces little increased. It is considered the side chain of the rubbed PI show the its abilities of the original capacities, while the side chain of the IB irradiated PI cannot show the its abilities of the original capacities due to the IB has already destroyed the side chain of the PI.

• Journal of Satellite, Information and Communications
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• v.7 no.3
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• pp.54-57
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• 2012

Nematic liquid crystal (NLC) alignment effects on SiOF layers via ion-beam (IB) irradiation for four types of incident energy were successfully studied. The effect of fluorine addition on silicon oxide film properties as a function of $SiOF_4/O_2$ gas flow ration was investigated. The SiOF thin film exhibits good chemical and the thermal stability of the SiOF thin film were sustained as function of the NLC alignment until $200^{\circ}C$ Also, the response-time characteristics of aligned LCD based on SiOF film were studied.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.301-301
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• 2008

Ion beam (IB)-induced alignment of inorganic materials has been investigated intensively as it provides controllability in a nonstop process for producing high-resolution displays[1][2]. LC orientation via ion-beam (IB) irradiation on the nitrogen doped diamond like carbon (NDLC) thin film deposited by physical deposition method-sputtering was embodied. The NDLC thin film that was deposited by sputter showed uniform LC alignment at the 1200eV of the ion beam intensity. The pretilt angle of LC on NDLC thin films was measured with various IB exposure time and angle. The maximum pretilt angle were showed with IB irradiation angle of $45^{\circ}$ and exposure time of 62.5 sec, respectively. To show NDLC thin film stability in high temperature, thermal stability test was proceeded. The uppermost of the thermal stability of NDLC thin film was $200^{\circ}C$. In this investigation, the electro-optical (EO) characteristics of LC on NDLC thin film were measured.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.413-416
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• 2004

In this study, zinc oxide(ZnO) having large misfit(18.2%) with sapphire was tried to be grown on very thin nitride buffer layers. For the creation of various kinds of nitride buffer layer, sapphire surface was modified by an irradiation of nitrogen ion beam with low energy generated from stationary plasma thruster(SPT) at room temperature. After the irradiation of ion beam, Al-N and Al-O-N bonding was identified to be formed as nitride buffet layers. Surface morphology was measured by AFM and then ZnO growth was followed by pulsed laser deposition(PLD). Their properties are analyzed by XRD, AFM, TEM, and PL. We observed that surface morphology was improved and deep level emission related to defects was almost vanished in PL spectra from the ZnO grown on nitride buffer layer.

• Corrosion Science and Technology
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• v.17 no.3
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• pp.123-128
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• 2018

The fabrication of a controlled surface is of great interest because it can be applied to various engineering facilities due to the various properties of the surface, such as self-cleaning, anti-bio-fouling, anti-icing, anti-corrosion, and anti-sticking. Controlled surfaces with micro/nano structures were fabricated using an ion beam focused onto a polypropylene (PP) surface with a fluoridation process. We developed a facile method of fabricating hydrophobic surfaces through ion beam treatment with argon and oxygen ions. The fabrication of low surface energy materials can replace the current expensive and complex manufacturing process. The contact angles (CAs) of the sample surface were $106^{\circ}$ and $108^{\circ}$ degrees using argon and oxygen ions, respectively. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FT-IR) spectroscopy were used to determine the chemical composition of the surface. The morphology change of the surfaces was observed by scanning electron microscopy (SEM). The change of the surface morphology using the ion beam was shown to be very effective and provide enhanced optical properties. It is therefore expected that the prepared surface with wear and corrosion resistance might have a considerable potential in large scale industrial applications.

• Journal of the Korean institute of surface engineering
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• v.24 no.3
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• pp.137-143
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• 1991

The relation between the ion irradiation induced grain growth and the basic parameters sinvolved in ion beam mixing process was studied. TEM micrographs showed that a significant grain growth has been induced by Ar+ irradiation at room temperature. The grain size increases rapidly in low dose region, while it approaches a saturated value in high dose region, and it has close relationship with nuclear energy deposition and thermodynamic properties such as cohesive energy ( Hc) and heat of mixing ( Hm). A model for the grain growth based on the thermal spike induced atomic migration was developed and applied to interpret experimental results.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.398-398
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• 2007

The Liquid Crystal (LC) alignment uniformity is very important in LC devices. The alignment mechanism of LC molecules on a rubbed polyimide (PI) surface is very important for both LC fundamental research and application. So, Generally a rubbing method to align LC has been widely used to mass-produce LCD panels. But because rubbing method is contact method between rubbing fabric and indium-tin-oxide glass or flexible substrate, rubbing method has some defects, such as the electrode charges and the creation of contaminating particles. Thus we strongly recommend a non-contact alignment technique for getting rid of some defects of rubbing method. Most recently, the LC aligning capabilities achieved by ion-beam exposure on the organic and nonorganic thin film surface have been reported successfully. In this research, we studied the tilt angle generation and electro-optical performances for a NLC on homeotropic polyimide surfaces with ion-beam exposure. The LC aligning capabilities of a nematic liquid crystal (NLC) on a homeotropic PI surface using a new ion-beam method were studied. On the homeotropic PI surface, the tilt angle of the NLC by exposure ion-beam had a tendency to decrease as increased ion-beam energy density. And, on the homeotropic PI surface, the alignment character of the NLC with respect to ion-beam energy was good. And we achieved satisfactory result for EO character.

• Progress in Medical Physics
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• v.31 no.2
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• pp.9-19
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• 2020

Purpose: This study aims to develop a multi-purpose electron beam irradiation device for preclinical research and material testing using the research electron linear accelerator installed at the Dongnam Institute of Radiological and Medical Sciences. Methods: The fabricated irradiation device comprises a dual scattering foil and collimator. The correct scattering foil thickness, in terms of the energy loss and beam profile uniformity, was determined using Monte Carlo calculations. The ion-chamber and radiochromic films were used to determine the reference dose-rate (Gy/s) and beam profiles as functions of the source to surface distance (SSD) and pulse frequency. Results: The dose-rates for the electron beams were evaluated for the range from 59.16 Gy/s to 5.22 cGy/s at SSDs of 40-120 cm, by controlling the pulse frequency. Furthermore, uniform dose distributions in the electron fields were achieved up to approximately 10 cm in diameter. An empirical formula for the systematic dose-rate calculation for the irradiation system was established using the measured data. Conclusions: A wide dose-rate range electron beam irradiation device was successfully developed in this study. The pre-clinical studies relating to FLASH radiotherapy to the conventional level were made available. Additionally, material studies were made available using a quantified irradiation system. Future studies are required to improve the energy, dose-rate, and field uniformity of the irradiation system.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.513-514
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• 2008

The potential of non-rubbing technology for applying to display devices was demonstrated by irradiating a high density argon ion beam (IB) on a polyimide (PI) as a liquid crystal alignment layer. The superior electro-optical characteristics were obtained, compared to rubbed PI, Although the low pretilt angle was created on the IB irradiated PI.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.446-446
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• 2008

The effects of proton beam irradiation on the yittria-stabilized zirconia (YSZ) pellets have been investigated using SEM, EDX and TGA. 130 keV proton beam was irradiated on YSZ with high doses and annealed at various temperatures. The ion conductivity was also measured as a function of proton irradiation temperature and annealing temperature and the results were compared with their corresponding SEM images and the results of SRIM calculations.