• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.334-335
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• 2006

Solid insulation exposed to voltage is degraded by electrical tree process. And the degradation of the insulation is accelerated by voltage application. For this experimental, specimen of electrical tree model is made by XLPE (cross-linked polyethylene). And the size of the specimen is 7*5*7 $mm^3$. Distance of needle and plane is 2 mm. Voltages applied for acceleration test are 12 kV to 15 kV. And distribution characteristic of degraded stage is studied too. As a PD detecting and data process, discharge data acquire from PD detecting system (Biddle instrument). The system presents statistical distribution as phase resolved. Moreover the processing time of electrical tree is recorded to know the speed of degradation according to voltage.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.29A no.2
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• pp.77-79
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• 1992

We propose a self-aligned and double recessed technique for GaAs power MESFETs application. The gate length and the wide recess width are defined by a selective removal of the SiN layer using reactive ion etching(RIE) while the depth of the channel is defined by chemical etching of GaAs layers. The threshold voltages and the saturation drain voltage could be sucessfully controlled using this technique. The lateral-etched distance increases with the dry etching time and the source-drain breakdown voltage of MESFET increases up to about 30V at a pinch-off condition. The electrical characteristics of a MESFET with a gate length of 2 x10S0-6Tm and a source-gate spacing of 33 x10S0-6Tm show maximum transconductance of 120 mS/mm and saturation drain current density of 170-190mA/mm at a gate voltage of 0.8V.

• Journal of the Optical Society of Korea
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• v.16 no.2
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• pp.181-184
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• 2012

We report, for the first time, operation frequency dependence of current density-voltage ($J_{OLED}-V_{OLED}$) shift for multi-layer organic light-emitting diodes (OLEDs). When the OLEDs were electrically stressed for 21 hours with 50% duty voltage pulses at 60, 120, 240, and 360 Hz, the JOLED-VOLED shifts were suppressed by half for 360 Hz operation compared with 60 Hz operation, but with little change in emission efficiencies. This frequency dependent $J_{OLED}-V_{OLED}$ shift is believed to be commonly observed for typical multi-layer OLEDs and can be used to further improve lifetime of digitally-driven active-matrix OLED displays.

• 전기의세계
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• v.20 no.3
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• pp.27-31
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• 1971

The main focus of this paper is on the study of the radiation effect upon the electrical property of a A-Kind insulator which is one of the organic insulators. The varnished cloth is so typical of the A-Kind insulators as to be selected for a sample. AC and Impluse voltage is applied to the variable Gamma ray irradiated dose samples with the constant time duration and the dielectric breakdown voltage are measured from the sample. The experimental data of the dielectric breakdown voltage are considerably decreased. The above conclusion is useful for the selection and application of the orgainc insulators under the irradiation effects.

• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.215-216
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• 2006

Solid insulation exposed to voltage is degraded by electrical tree process. And the degradation of the insulation is accelerated by voltage application. For this experimental, specimen of e1ectrical tree model is made by XLPE (cross-linked polyethylene). And the size of the specimen is $7*5*7\;mm^3$. Distance of need1e and plane is 2 mm. Voltages applied for acceleration test are 12 kV to 15 kV. And distribution characteristic of degraded stage is studied too. As a PD detecting and data process, discharge data acquire from PD detecting system (Biddle instrument). The system presents statistical distribution as phase resolved. Moreover the processing time of electrical tree is recorded to know the speed of degradation according to voltage.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1387-1388
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• 2007

Solid insulation exposed to voltage is degraded by electrical tree process. And the degradation of the insulation is accelerated by voltage application. For this experiment, specimens of electrical tree models were made by three types of XLPE (cross-linked polyethylene). And distribution characteristics of degraded stages are studied too. As a method of detecting and data process, discharge data was acquired from PD detecting system (Biddle instrument). And microscope and digital camera were used to observe the morphologies of the electrical tree to divide stages of the tree. The system presents statistical distribution as phase resolved. Moreover the processing time of electrical tree is recorded to know the speed of degradation according to voltage.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.479-480
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• 2007

This paper reports the results of time-domain simulation for the KEPCO metropolitan system with a secondary voltage regulation (SVR) model, developed with TSAT user defined model blocks. The previously proposed model in the literature needs switching blocks for converting level signals generated by a regional voltage regulator (RVR) into settings of reactive generation. This paper modified the SVR model not to incorporate the switching blocks, so it is much easier to implement the modified model on the simulation tool.

• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.8-10
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• 2019

In this paper, a bidirectional three-phase push pull converter is analyzed for the high power, wide voltage range applications. From comparison analysis of two switching methods: PWM plus phase-shift (PPS) and dual-asymmetric PWM (DAPWM) with the effect of dead-time, the proposed hybrid control is aimed to reduce the circulating current under wide voltage range operation. Value of leakage inductance effect to the peak current value, current stress and conduction loss in facing the load variation. Trade-off between power range and slew rate of transformer current was analyzed for properly selecting value of the transformer leakage inductance. Experimental results from a 22-kW prototype are provided to validate the proposed concept.

• Journal of information and communication convergence engineering
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• v.18 no.4
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• pp.222-229
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• 2020

Recent multi-core processors for smart devices use per-core dynamic voltage and frequency scaling (DVFS) that enables independent voltage and frequency control of cores. However, because the conventional task scheduler was originally designed for per-core DVFS disabled processors, it cannot effectively utilize the per-core DVFS and simply allocates tasks evenly across all cores to core utilization with the same CPU frequency. Hence, we propose a novel task scheduler to effectively utilize percore DVFS, which enables each core to have the appropriate frequency, thereby improving performance and decreasing energy consumption. The proposed scheduler classifies applications into two types, based on performance-sensitivity and allows a performance-sensitive application to have a dedicated core, which maximizes core utilization. The experimental evaluations with a real off-the-shelf smart device showed that the proposed task scheduler reduced 13.6% of CPU energy (up to 28.3%) and 3.4% of execution time (up to 24.5%) on average, as compared to the conventional task scheduler.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.38 no.2
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• pp.38-49
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• 2001

This paper presents a new voltage down converter(VDC) using charge and discharge current adjustment circuitry that provides high frequency application. This VDC consist of a common driving circuit and compensation circuits: 2 sensors and each driving transistors for controlling gate current of driving transistor. These sensors are operated as adaptive biasing method with high speed and low power consumption. This circuit is designed with a $0.62{\mu}m$ N well CMOS technology. In H-spice simulation results, internal voltage is bounded ( IV, +0.6V) in proposed circuitry when load current rapidly increases and decreases during Gns between 0 and $200m{\Lambda}$. And the recovery time of internal voltage is about 7ns and 10ns when load current increases and decreases respectively. That is fast better than common driving circuit. Total power consumption is about 1.2mW.