• Korean Journal of Optics and Photonics
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• v.16 no.4
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• pp.376-383
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• 2005

We designed and fabricated integrated-optic tunable polarization controllers based on $LiNbO_3$ with the Ti-indiffused waveguide along the y-axis utilizing the electro-optic effect. The device consists of $TE↔TM$ mode converters and TE/TM phase shifters. We analyzed the operation principles of each device utilizing transfer matrices based on a Jones matrix and simulated shifting of the center wavelength by inducing voltage. We confirmed experimentally that the fabricated devices control the tunability of the center wavelength and the input SOP.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.58-58
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• 2010

Carbon nanotubes (CNTs) have been extensively studied owing to its superior electrical properties, especially high electron mobility, which can be applied to various nano-electronic devices. However, synthesized CNTs have a mixture of metallic and semiconducting tubes so that their separation has been a tremendous obstacle to the practical application in electronic device structures. Among the different separation methods, electrical breakdown process to selectively burn out the metallic tubes has been quite successful though it needs additional process in the fabrication of device structures. Here, we report on the selective but not perfect growth of semiconducting nanotubes via use of diluted ferritin catalyst. SWCNTs were grown on ferritin catalyst, where the concentration of the ferritin solution was changed. In this way, we could fabricate the electrical breakdown free SWCNT thin film transistors on the flexible polyimide (PI) substrate. When we used the ferritin diluted by 1/2000, ~ 60 % of the SWCNT thin film transistors showed a perfect p-type behavior with an on/off current ratio higher than $10^5$ and on-current greater than $10^{-7}$ A. We will also discuss the photo-response of such formed thin film transistors over both visible and UV light.

• Applied Science and Convergence Technology
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• v.26 no.6
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• pp.208-213
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• 2017

Flexible opto-electronic devices are developed on the insulating layer deposited stainless steel (STS) substrates. The silicon dioxide ($SiO_2$) material as the diffusion barrier of Fe and Cr atoms in addition to the electrical insulation between the electronic device and STS is processed using the plasma enhanced chemical vapor deposition method. Noble silver (Ag) films of approximately 100 nm thickness have been formed on $SiO_2$ deposited STS substrates by E-beam evaporation technique. The films then were annealed at $650^{\circ}C$ for 20 min using the rapid thermal annealing (RTA) technique. It was investigated the variation of the surface morphology due to the interaction between Ag films and $SiO_2$ layers after the RTA treatment. The results showed the movement of Si atoms in silver film from $SiO_2$. In addition, the structural investigation of Ag annealed at $650^{\circ}C$ indicated that the Ag film has the material property of p-type semiconductor and the bandgap of approximately 1 eV. Also, the films annealed at $650^{\circ}C$ showed reflection with sinusoidal oscillations due to optical interference of multiple reflections originated from films and substrate surfaces. Such changes can be attributed to both formation of $SiO_2$ on Ag film surface and agglomeration of silver film between particles due to annealing.

• Journal of the Korean Society of Radiology
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• v.1 no.3
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• pp.11-16
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• 2007

In this study, the potential of a newly developed simulation toolkit, GATE for the simulation of electronic portal imaging devices (EPID) in radiation therapy was evaluated by characterizing the performance of the metal plate/phosphor screen detector for EPID. We compared the performances of the GATE simulator against MCNP4B code and experimental data obtained with the EPID system in order to validate its use for radiation therapy.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.5
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• pp.3079-3085
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• 2014

This paper suggests a power level controllable frequency up-converter which is designed and fabricated using both the filtering technology consisted with only passive devices and a multi-level digital attenuator. The suggested frequency up-converter simultaneously realizes the low power consumption and the low cost model. Because of the possibility for controlling power levels, it is possible to use the suggested frequency up-converter for wide spectral range. According to the experimental results, the average gain value of 0.75dB is obtained for the bandwidth of 160MHz at the center frequency of 1,200MHz. Especially, it is confirmed that the power level can be controlled from 10 to -21.5dBm through the digital attenuator.

• Journal of Korea Multimedia Society
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• v.17 no.5
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• pp.613-622
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• 2014

In spite of the convenience and cost-effectiveness of an electronic document management system the paper-type documents still should be stored for a comparison against the original documents. In this paper, for the efficient management of paper documents, we designed and implemented a document management system using smart devices equipped with NFC(Near Field Communication) technology. To implement the proposed system we designed a database for document management and developed an Android application for smart device using Eclipse 3.0 and Java programming. Whenever we touch the smart phone on the NFC tags which are attached to the paper-type documents and document boxes, it is possible to registering, searching and carrying in and out services for documents and boxes. This study provides smart phone users with systematic, economical and convenient paper-type documents management functions, and thus enhances the business efficiency.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.518-521
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• 2004

We have investigated about compensation film to reduce the light leakage at an oblique angle in-plane switching mode. It is well known that uncompensated in-plane switching (US) and fringe field switching (FFS) liquid crystal displays (LCDs) have much better viewing angle than other modes owing to the in-plane rotation of the LC director. However, to accomplish optimal viewing angle characteristics in these devices, they must be compensated by one or more films. So, in this paper, we have studied how to reduce the light leakage with viewing angle using discotic film in dark state.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.939-942
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• 2004

Al doped Zinc Oxide(ZnO:Al) films, which is widely used as a transparent conductor in optoelectronic devices such as solar cell, liquid crystal display, plasma display panel, thermal heater, and other sensors were Prepared by using the capacitively coupled RF magnetron sputtering method. In this paper the effect of RF discharge power on the electrical, optical and structural properties were investigated experimentally. The results show that the structural and electrical properties of the film are highly affected by the variation of RF discharge power. The optimum growth conditions were obtained for films doped with 2 wt% of $Al_2O_3$ and 200 W in RF discharge power, which exhibit a resistivity of $10.4{\times}10^{-4}{\Omega}-cm$ associated with a transmittance of 89.66 % for 1000nm in films thickness in the wavelength range of the visible spectrum.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.10
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• pp.1835-1839
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• 2008

Power management is a very important issue in portable electronic applications. Portable electronic devices require very efficient power management like LDO to increase the battery life. As the voltage variation of battery power is large in the application of cell phone, camera, laptop, automotive, industry application and so on, battery power is not directly used and LDO is used to supply the power of internal circuit. Besides, LDO can supply DC voltage that is lower than bauer voltage and constant DC voltage that is not related to largely fluctuated battery power. In the study, the power-save mode current and IR-drop characteristics are analyzed from a LDO with on-chip fabricated in 0.18-um CMOS technology.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.139-142
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• 2009

Rapid developments in the field of electronic communication have given people's daily life much more convenience and abundance. However, making precise electrical and electronic devices and control systems lighter, smaller, and faster have caused lots of problems such as interference of external electric source, malfunction brought by electric fast transient(EFT), and influence on human body. In this research, the EMC filter in the high powered breaker was designed and fabricated as a countermeasure. The filter attenuated noise more than 30 ~ 75 dB in the range of 10 MHz ~ 1.5 GHz. And, when the EFT of 4 kV in the level 4 of IEC 61000-4-4 was induced, it was soon suppressed to 600 V.