• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.11
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• pp.538-543
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• 2006

A high-Power continuous-wave (CW) ten-vane double-strapped magnetron oscillator has been investigated using three-dimensional (3D) particle-in-cell (PIC) numerical simulation code, MAGIC3D. The resonant modes and their resonant frequencies of the ten-vane strapped magnetron resonator were obtained to show a large mode separation near the ${\pi}$-mode. An electron cloud formed in an anode-cathode gap, called an interaction space was confined well enough to result in no leakage current. Five spokes were clearly observed in the electron cloud, which definitely ensured the ${\pi}$-mode oscillation in the ten-vane magnetron. Numerical simulations predicted that the saturated microwave output power measured at the coaxial output port was 5.41 kW at the microwave frequency of 893 MHz, corresponding to a power conversion efficiency of 72.6% when the external axial magnetic field was 1150 gauss and the electron beam voltage and current were 6 kV and 1.25 A, respectively.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.481-484
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• 2008

In order to reduce IR drop through common electrode in AMOLED, we propose a novel method to form electrical contact between highly-conductive bus lines and common electrode by using a plasma-assisted patterning of OLED layers and double deposition of the common electrode. Plasma-assisted patterning effects on OLED performance and degradation have been investigated. This patterning method caused turn-on voltage decrease, current flow increase at the same applied OLED voltages, quantum efficiency decrease, and rapid degradation at early stage during the lifetime test. However, comparable 70% luminance lifetime were obtained for both patterned and non-patterned OLEDs.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1008-1011
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• 2005

In this study, the field emission display with carbon nanotube emitter is developed for the large size HDTV application. Two structures for electron beam focusing are developed on the typical top-gate cathode. The metal grid and focusing gate structure are proved to be effective for the focusing. The data switching voltage for the double gate structure is lower than 30V which is competitive value in respect of the cost for driver electronics. The brightness and color gamut are comparable to those of the commercial product such as CRT.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1156-1157
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• 2008

The use of the pulsed electro acoustic (PEA) method allowed us to perform the direct observations of spatio-temporal charge distributions in Electric double layer capacitors (EDLCs) based on polarizable nanoporous carbonaceous electrode. The negative charge density became the maximum, about 205 $C/m^3$ at the region where was near to collector layer in EDLCs for case $V_{DC}$ = 2.5 V, while the positively charged density became the maximum, about 61.1 $C/m^3$ at the region where it was located around the cathode layer. The PEA measurement used here is a very useful method to quantitively investigates the spatio-temporal charge distribution in EDLCs.

• 한국정보디스플레이학회:학술대회논문집
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• 2000.01a
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• pp.125-126
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• 2000

We report the use of fluorene based copolymers containing quinoline(POF66, PIF66) and pyridine(PFPV) units as electron transporting polymers for multi-layered LEDs. Double-layer device structure combining PIF66 as electron-transporting layer with the emissive MEHPPV showed a maximum quantum efficiency of 0.03%, which is 30 fold increased compared with ITO/MEHPPV/Al single-layer device. PFPV layer increased the quantum efficiency up to 0.1% in the device structure of ITO/(P-3:PVK)/PFPV/Al. The ETL with the electron deficient moiety improved the LED performance by the characteristics of electron transporting as well as hole blocking between emissive layer and metal cathode.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.9
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• pp.873-877
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• 2006

We have fabricated top omission organic light emitting diodes with transparent Ba/Ag double layer cathodes deposited by using thermal evaporation method. The device structure was $glass/Ni(200nm)/2-TNATA(15 nm)/{\alpha}-NPD(15nm)Al_{q3}:C545T\;(1%,\;35nm)/BCP(5nm)/Ba(10nm)/Ag(8nm)$. The optical transmittance of the Ba(10 nm)/Ag(8 nm) layer was over 60 % in the visible wavelength region. The maximum efficiency of the device was $13.7\;cd/A\;at\;0.69\;mA/cm^{2}$ and the efficiency of over 10 cd/A was achieved at wide range of current densities and luminances.

• Journal of Korean Neurosurgical Society
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• v.54 no.6
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• pp.484-488
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• 2013

Objective : To examine the synergistic effects of both computer-assisted cognitive rehabilitation (CACR) and transcranial direct current stimulation (tDCS) on cognitive function in patients with stroke. Methods : The current double-blind, sham-controlled study enrolled a total of 11 patients who were newly diagnosed with stroke. The patients of the tDCS group (n=6) completed sessions of the Korean computer-assisted cognitive rehabilitation program five times a week for 30 minutes a session during a mean period of 18.5 days concomitantly with the anodal tDCS over the bilateral prefrontal cortex combined with the CACR. The patients of the control group (n=5) also completed sessions of the sham stimulation during a mean period of 17.8 days. Anodal tDCS over bilateral prefrontal cortex (F3 and F4 in 10-20 EEG system) was delivered for 30 minutes at an intensity of 2 mA. Cathode electrodes were applied to the non-dominant arm. All the patients were evaluated using the Seoul Computerized Neuropsychological Test (SCNT) and the Korean Mini-Mental State Examination. Results : Mann-Whitney U test revealed a significant difference between the two groups. The patients of the tDCS group achieved a significant improvement in the post/pre ratio of auditory continuous performance test and visual continuous performance test on the SCNT items. Conclusion : Our results indicate that the concomitant use of the tDCS with CACR to the prefrontal cortex may provide additional beneficial effects in improving the cognitive dysfunction for patients with stroke.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.3
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• pp.14-19
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• 2000

Free-standing GaN single crystal substrates have been obtained by growing thick GaN epitaxial layers on (0001) sapphire substrates using hydride vapor phase epitaxy (HVPE) method. After growing the GaN thick film of 200 ${\mu}{\textrm}{m}$, a free-standing GaN with a size of 10 mm $\times$10 mm were obtained by mechanical polishing process to remove sapphire substrate. Crack-free GaN substrates have been obtained by GaCl pre-treatment prior to the growth of GaN epitaxial layers. Properties of free-standing GaN substrates have been compared with those of lateral epitaxial overgrowth (LEO) GaN films by double-crystal x-ray diffraction (DC-XRD), cathodoluminescence (CL) and photoluminescence (PL) measurements.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.3
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• pp.241-246
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• 2012

A layered planer SOFC module was designed from planar-type SOFC. It was prepared by multi-layered ceramic technology. To form the cathode and the anode in the layered structure, reliable channels should be made on the both side of electrolyte perpendicularly. However, monolithic SOFC using multi-layered ceramic technology hasn't been studied another group, and the warpage of electrolyte in the channel, also, hasn't been studied, when electrode is printed on the electrolyte. In this study, the channels are prepared with electrode printing, and their warpage are evaluated. In the case of YSZ without electrode, the warpages are nothing in the limit of measurement using optical microscope. The warpage of 'YSZ-NiO printed' increases than that of 'NiO printed', and also, the case of 'double electrode printed' is similar to 'YSZ-NiO printed'. It is thought that, in the printed electrolyte, the warpage is related to the difference of the sintering behavior of each material.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05b
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• pp.22-25
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• 2001

A thyristor switch circuit for capacitor discharge application, of which the equivalent circuit includes a resistor between cathode and gate of a reverse-conducting thyristor and an avalanche diode anti-parallel between its anode and gate to set thyristor tum-on voltage, is monolithically integrated by planar process with AVE double-implantation method. To ensure a lower breakdown voltage of the avalanche diode for thyristor tum-on than the break-over voltage of the thyristor, $p^+$ wells on thyristor p base layer are made by boron implantation/drive-in for a steeper doping profile with higher concentrations while rest p layers of thyristor and free-wheeling diode parts are formed with Al implantation/drive-in for a doping profile of lower steepness. The free-wheeling diode part is isolated from the thyristor part by formation of separated p-well emitter for suppressing commutation between them, which is achieved during the formation of thyristor p-base layer.