• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.1114-1117
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• 2004

We investigated the liquid crystal (LC) alignment phenomena using hydrogenated amorphous carbon (a-C:H) thin films. For LC alignment, the surface of a-C:H thin films is treated with low energy ion beam. We investigated the relationship between the properties of a-C:H thin films and LC alignment phenomena.

• Proceedings of the Korean Vacuum Society Conference
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• 1996.02a
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• pp.87-87
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• 1996

• Journal of Electrical Engineering and Technology
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• v.1 no.3
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• pp.359-365
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• 2006

Since the start of the KSTAR (Korea Superconducting Tokamak Advanced Research) project, Instrumentation and Control (I&C) of the Neutral Beam Test Facility (NB-TF) has been striving to answer diverse requests arising from various facets during the project's development and construction phases. Hard-wired electrical circuits have been designed, tested, fabricated, and finally installed to the relevant parts of the system. In relation to the vacuum system I&C, controlling functions for the rotary pumps, a Roots pump, two turbomolecular pumps, and four cryosorption pumps have been constructed. I&C for the ion source operation are the temperature and flow rate signal monitoring, Langmuir probe signal measurements, gradient grid current measurements, and arc detector circuit. For the huge power system to be monitored or safely operated, many temperature measurement functions have also been implemented for the beam line components like the neutralizer, bending magnet, ion dump, and calorimeter. Nearly all of the control and probe signals between the NB test stand and the control room were made to be transmitted through the optical cables. Failures of coolant flow or beam line vacuum pressure were made to be safely blocked from influencing the system by an appropriate interlock circuit that will shut down the extraction voltage application to the system or prevent damages to the vacuum components. Preliminary estimation of the beam power through the calorimetric measurement shows that 87.9% of the total power of the 60kV/18A beam with 200 seconds duration is absorbed by the calorimeter surface. Most of these I&C results would be highly appropriate for the construction of the main NBI facility for the KSTAR national fusion research project.

• Proceedings of the Korean Nuclear Society Conference
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• 2004.10a
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• pp.674-674
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• 2004

• Proceedings of the Korean Vacuum Society Conference
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• 1996.02a
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• pp.92-92
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• 1996

• Solar Energy
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• v.20 no.2
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• pp.55-65
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• 2000

Better electrical and optical properties of ITO thin films were demanded for the window layer of CdS/CdTe solar cells. To match that demand, an ion beam sputtering system was used for the deposition of ITO thin films. The substrate temperature and ion beam energy were controlled to deposit high quality ITO thin films in two cases of Ar ion sputtering and Ar+$O_2$ ion sputtering. The microstructure changed from domain structure in ITO deposited by Ar ions to grain structure in ITO deposited by Ar+$O_2$ ions. The lowest resistivity of ITO films was $1.5\times10^{-4}{\Omega}cm$ at $100^{\circ}C$ substrate temperature in case of Ar ions sputtering. Transmittance in the visible range was over 80% above $100^{\circ}C$ substrate temperature.

• Nuclear Engineering and Technology
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• v.29 no.3
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• pp.181-185
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• 1997

The ion sources for induction linac driven heavy ion fusion were fabricated and their omittance characteristics were investigated. For to kinds of ion sources, i. e. a carbon vacuum arc ion source and a cusp field rf ion source, the emittance was measured with a double slit beam scanner. The required normalized omittance of an ion source for heavy ion fusion is 10$^{-7}$ - 5$\times$10$^{-7}$ $\pi$ m-rod, and the measured emittances of the ion beams from carbon vacuum arc ion source and cusp field rf ion source (Ne$^{+}$) were 2$\times$10$^{-6}$ $\pi$ m-rad and 4$\times$10$^{-7}$ $\pi$ m-rad, respectively.y.

• Nuclear Engineering and Technology
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• v.55 no.3
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• pp.939-946
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• 2023

Comprehensive Research Facility for Fusion Technology (CRAFT) is an integration of different demonstrating or testing facilities, which aim to develop the critical technology or composition system towards the fusion reactor. Due to the importance and challenge of the negative ion based neutral beam injection (NNBI), a NNBI test facility is included in the framework of CRAFT. The initial object of CRAFT NNBI test facility is to obtain a H⁰ beam power of 2 MW at the energy of 200-400 keV for the pulse duration of 100 s. Inside the negative ion accelerator of NNBI system, the interactions of the negative ions with the background gas and electrodes can generate abundant stray electrons. The stray electrons can be further accelerated and dumped on the electrodes or eject from the accelerator. The stray electrons, including the ejecting electrons, cause the unwanted particle and heat flux onto the electrodes and the inner components of beamline (especially the temperature sensitive cryopump). The suppression of the stray electrons from the CRAFT accelerator is carried out via a series of design and simulation works. The paper focuses the influence of different magnetic field configurations on the stray electrons and the character of the ejecting electrons.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.243.1-243.1
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• 2014

For two-dimensional grid electrodes immersed in plasmas, sheath expansion due to negative high-voltage pulse applied to the electrode generates high-energy pseudowave. The high-energy pseudowave can be used as ion beam for ion implantation. To estimate ion dose due to high-energy pseudowave, investigation on sheath expansion of grid electroes is necessary. To investigate sheath expansion, an analytic model was developed by Vlasov equation and applying the 1-D sheath expansion model to 2-D. Because of lack of generalized 2-D Child-Langmuir current, model cannot give solvable equation. Instead, for a given grid electrode geometry, the model found the relations between ion distribution functions, Child-Langmuir currents, and sheath expansions. With these relations and particle-in-cell (PIC) simulations, for given grid electrode geometry, computation time was greatly reduced for various conditions such as electrode voltages, plasma densities, and ion species. The model was examined by PIC simulations and experiments, and they well agreed.

• Journal of the Korean Vacuum Society
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• v.15 no.4
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• pp.387-394
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• 2006

In this study, the effect of using a neutral beam formed by low-angle forward reflection of a reactive ion beam on aspect-ratio-dependent etching (ARDE) has been investigated. When a SF6 Inductively Coupled Plasma and $SF_6$ ion beam etching are used to etch poly-Si, ARDE is observed and the etching of poly-Si on $SiO_2$ shows a higher ARDE effect than the etching of poly-Si on Si. However, by using neutral beam etching with neutral beam directionality higher than 70 %, ARDE during poly-Si etching by $SF_6$ can be effectively removed, regardless of the sample conditions. The mechanism for the removal of ARDE via a directional neutral beam has been demonstrated through a computer simulation of different nanoscale features by using the two-dimensional XOOPIC code and the TRIM code.