• The Transactions of the Korean Institute of Power Electronics
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• v.15 no.1
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• pp.52-59
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• 2010

The conventional CCFL (Cold Cathode Fluorescent Lamp) inverter used in the backlight unit for LCD-TV, composed of the three power stage, can degrade the whole power conversion efficiency. In this paper, a novel scheme to drive the CCFL, composed only of the two power stage without using a dc/dc power stage, is proposed to enhance the whole power conversion efficiency. By adopting the proposed "4-in-1 Transformer", the current balance and the simultaneous ignition among the four CCFL lamp are assured with the one inverter circuit. The proposed scheme features the simple circuit structure, which can save the volume and the cost in the LCD backlight unit. Design considerations are discussed and design procedures are derived. Experimental results of the proposed scheme for 40" LCD-TV are presented to confirm the theoretical analysis.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.547-547
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• 2013

This paper presents the understandings carried out for the installation of the hydrogen reservoir of the multi-gap pseudospark switch under developing for the accelerator applications. As a cold cold cathode switch, the pseudospark switch could replace the thyratron switch which has hot cathode and being used well currently in the high power field such as laser and accelerator applications. Especially in the klystron modulator, the key component is a switch which mostly defines the jitter and the instability of the modulator system. To get the less jitter and the instability, we need to find proper range of the pressure for the gas discharge inside gas switch. This could be achieved by the understanding of the characteristic of the nonevaporable getter (NEG) which is used as a hydrogen reservoir for the switch. Therefore we verified the characteristics of the NEG (St 172, Saes) and its installation in the switch. Finally we controlled the getter to find best pressure point for the pseudospark switch.

• Proceedings of the KIEE Conference
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• 1995.07c
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• pp.1051-1053
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• 1995

Nowadays perovskite $La_{1-x}Sr_xMnO_3$ is preferred cathode material in Solid Oxide Fuel cell(SOFC). The $La_{1-x}Sr_xMnO_3$ with Sr contents ranging $x=0{\sim}1.0$ were prepared by a citrate method. These powders were characterized by usual means like TG/DTA, X-ray diffraction analysis. The samples used for measuring thermal expansion were prepared as pellets by cold pressing and subsequent sintering in air at $1200^{\circ}C$ for 5 hours. To measure the by-product of $La_{1-x}Sr_xMnO_3$ reacted with 8mol% YSZ, that samples were sintered at $1200^{\circ}C$ for 5 hours.

• Journal of the Microelectronics and Packaging Society
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• v.18 no.3
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• pp.67-74
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• 2011

Keys to high wiring density semiconductor packages include flip-chip bonding and build-up substrate technologies. The current issues are the establishment of a fine pitch flip-chip bonding technology and a low coefficient of thermal expansion (CTE) substrate technology. In particular, electromigration and thermomigration in fine pitch flipchip joints have been recognized as a major reliability issue. In this paper, electromigration and thermomigration in Cu/Sn-3Ag-0.5Cu (SAC305)/Cu flip-chip joints and electromigration in Cu/In/Cu flip chip joints are investigated. In the electromigration test, a large electromigration void nucleation at the cathode, large growth of intermetallic compounds (IMCs) at the anode, a unique solder bump deformation towards the cathode, and the significantly prolonged electromigration lifetime with the underfill were observed in both types of joints. In addition, the effects of crystallographic orientation of Sn on electromigration were observed in the Cu/SAC305/Cu joints. In the thermomigration test, Cu dissolution was accelerated on the hot side, and formation of IMCs was enhanced on the cold side at a thermal gradient of about $60^{\circ}C$/cm, which was lower than previously reported. The rate of Cu atom migration was found comparable to that of electromigration under current conditions.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05a
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• pp.32-34
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• 2001

we have quantitatively investigated the possibility of feeding oxygen radical in air environment. The oxygen radical generation from the plasma was verified and its efficiency was found to be dependent on the cathode material by the analysis with optical emission spectroscopy as well as by the quartz crystal micro-balance method.

• Journal of the Microelectronics and Packaging Society
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• v.11 no.2 s.31
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• pp.37-41
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• 2004

Parallel combination of cold chathode fluorescent lamps (CCFL) are widely used as the light sources of LCD TV backlight. Brightness uniformity is safisfied by using one transformer per one CCFL. Instead of using one transformer per oneCCFL, one transformer is used to drive 8 CCFLs by using differential driving method. A differential driving inverter with two transformers is developed to drive 16 CCFLs of 26' backlight for LCD TV. The brightness uniformity of $88\%$ was obtained by driving 26' backlight with the developed differential driving inverter successfully.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.08a
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• pp.403-411
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• 1999

The steel plate for shadow mask is used in a Cathode-ray tube of TV monitor and is the strictest product in surface quality because hundreds thousand of holes are perforated in a plane of 25 ${\times}$25 inches. To mass-produce this product, a reversible cold rolling mill for silicon steel was used and the rolling technology and the activity for quality improvement are described in this work. Because the steel plate is a mild steel, which is very sensitive to strip-breakage even in a low tension, we reset the minimum tension values matching to the operating conditions. The roll mark due to the multi-segmented araangement of shape controlling roll was prevented by hardening the intermediate shape controlling roll and by changing the existing working-roll into a HSS (Hig Speed Steel) roll. The scratch caused by the speed difference between a idle roll and a strip was prevented by increasing the roll roughness. With these activities, the steel plate for shadow mask can be stable. The continuous improvement of quality is, however, required for the customer satisfaction both of domestic and overseas market.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.1199-1201
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• 2002

Today, the ceramic transformer becomes widely used for the TFT LCD backlight inverter system thanks to its high efficiency and small size. In this paper, a high efficient inverter system for cold cathode flourescent lamp (CCFL) including PLL controller for tuning the PWM frequency to the frequency that the efficiency of the inverter system becomes maximum is proposed. The control IC implementing this feature will be released by Interpion Co. Ltd. in May 2002.

• Applied Microscopy
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• v.47 no.3
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• pp.86-94
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• 2017

In this study, we will describe a new design of carbon nanotubes tip. Single-walled carbon nanotubes produced using high-pressure CO over Fe particles (HiPCO) at CNI, Houston, TX used in this study. These tips were manufactured by employing a drawing technique using glass puller. Field electron microscopies with tips (cathode) to screen (Anode) separation of ~10 mm was used to characterize the electron emitters. The system was evacuated down to base pressure of (${\sim}10^{-8}$ mbar) when baked at up to (${\sim}200^{\circ}C$) over night. An electron field emission patterns, as well as current versus voltage characteristics and Fowler-Nordheim plots, are discussed.

• Journal of the Korean Vacuum Society
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• v.10 no.4
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• pp.411-415
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• 2001

Using the plasma that we developed to generate a low-temperature plasma at atmospheric pressure, we have investigated the etching possibility of tin oxide $(SnO_2)$ thin films. Hydrogen and methane radicals generated from the plasma were observed and their intensity was found to be dependent on the cathode material by an analysis with optical emission spectroscopy as well as by the plasma impedance. The etching ability of this plasma was evaluated by an emission intensity as well as by the evaluation of impedance using a plasma I-V curve.