• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.3
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• pp.255-260
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• 2023

In order to spread LED lighting, LED lighting technology directly driven by alternating current (AC) commercial power has recently been introduced. Since current does not flow at a voltage lower than the threshold voltage of the LED, a non-conductive section occurs in the current waveform, and the higher the threshold voltage of the LED, the more discontinuous current waveforms are generated. In this paper, multi-LED modules are connected in series so that the threshold voltage can be adjusted according to the number of LED modules. A small number of LED modules are driven at a low instantaneous rectified voltage, and a large number of LED modules are driven at a high instantaneous rectified voltage to lengthen the overall lighting time of AC-LED lighting, thereby minimizing the luminance deviation of AC-LED lighting. In addition, the load current flowing through the LED module is adjusted to be the same as the design current even at the maximum rectified voltage higher than the design voltage, so that the light brightness of the LED module is kept constant. Therefore, even if the rectified voltage applied to the LED module changes, the AC-LED lighting in which the light brightness is constant and the luminance deviation is minimal has been realized.

• The Journal of the Korea institute of electronic communication sciences
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• v.19 no.5
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• pp.1059-1066
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• 2024

Cosmic radiation poses a significant threat to the reliability of electronic devices. Cosmic radiation mainly consists of high-energy particles emitted from the sun, and there is no protection device to absorb or disperse these particles in the vacuum of space. Exposure to these high-energy particles can cause fatal damage to semiconductor devices, especially memory devices, and this can have serious implications for the entire space industry. Therefore, in this paper, we propose a new memory bit cell design method that can maintain high reliability in a space radiation environment.

• Transactions on Electrical and Electronic Materials
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• v.15 no.5
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• pp.253-256
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• 2014

$Pb(Zr_{0.52}Ti_{0.48})O_3$ thin films of $1.5{\mu}m$ thickness were grown on $Pt/Ti/Gd_3Ga_5O_{12}$ substrate by RF magnetron sputtering at annealing temperatures ranging from $550^{\circ}C$ to $700^{\circ}C$. We evaluated the residual stress, by using a William-Hall plot, as a function of the annealing temperatures of PZT thin film with a constant thickness. As a result, the residual stresses of PZT thin film of $1.5{\mu}m$ thickness were changed by varying the annealing temperature. Also, we measured the hysteresis characteristic of PZT thin films of $1.5{\mu}m$ thickness to evaluate for application of an optoelectronic device.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.1
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• pp.113-119
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• 2013

In this paper, n order to degrade of diagnosis of power supply by using Poincare map and fractal dimension with temperature measured by infrared camera. we review the characteristic of temperature variation according to pattern variation of power supply in chemical industry complex. As a simulation results we can be realized the characteristic behaviors of nonlinear dynamics in the poincare mal and fractal dimension. In the future verification method requires through additional research.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.11
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• pp.1173-1178
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• 2011

The power generated by wind turbines changes rapidly because of the continuous fluctuation of wind speed and direction. It is important for the power industry to have the capability to predict the changing wind power. In this paper, neural network based wind power prediction scheme which uses wind speed and direction is considered. In order to get a better prediction result, compression function which can be applied to the measurement data is introduced. Empirical data obtained from wind farm located in Kunsan is considered to verify the performance of the compression function.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.233-233
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• 2009

Piezoelectric Transformer (PT) was emerged in device and material industry. PT has some advantages such as low profile and mechanical energy transfer with little electromagnetic interface (EMI). But, It is known that the maximum PT efficiency can be obtained when it operates near the resonant frequency of the PT. Also PT's resonant frequency moves according to the load conditions Therefore, As the operating frequency moves further from the resonant frequency, the PT efficiency decreases dramatically due to the increase of the circulating current. This paper proposes analyzes modeling of PT convert and propose a guide-line to adaptive control

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.70-70
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• 2009

In this paper, we proposed 2500V Non punch-through(NPT) Insulated gate bipolar transistor(IGBT) for high voltage industry application. we carried out optimal simulation for high efficiency of 2500V NPT IGBT according to size of device. In results, we obtaind design parameter with 375um n-drift thickness, 15um gate length, and 8um emitter windows. After we simulate with optimal parameter, we obtained 2840V breakdown voltage and 3.4V Vce,sat. These design and process parameter will be used designing of more 2000V NPT IGBT devices.

• Proceedings of the IEEK Conference
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• 2001.06c
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• pp.43-46
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• 2001

This thesis proposes the design method of intelligent robot agent system and deals with the implementation of the system which is able to produce key internet statistics. It is believed that the statistics lead to effective investment from internet industry on its development. The system consists of robot agent process module, statistics production module and management module, and has an algorithm that can produce periodically the number of domestic homepages, active domain using .kr or gTLD and intenet hosts. It provides the result of the implementation and performance of the system as well.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.4
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• pp.290-295
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• 2016

Socket-outlets and plugs are essential devices that supply electric power into user appliances. During plug-out operation of an engaged plug from the socket-outlet, the consistent arc between the plug and the socket-outlet could develop into heavy fires in DC systems but only a small spark in AC systems. This paper proposes a pre-/post-electrode method to prevent plugs and socket-outlets from melting by sustaining arc energy. To implement the proposed pre-/post-electrodes, an experimental plug is manufactured with two electrodes, in which a post resistance Rs is connected in between. This paper investigates the function of the post resistance Rs, in which the best value of the post resistance Rs is obtained through simulation and experiment.

• Transactions on Electrical and Electronic Materials
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• v.16 no.6
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• pp.312-316
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• 2015

Through silicon via (TSV) technology holds the promise of chip-to-chip or chip-to-package interconnections for higher performance with reduced signal delay and power consumption. It includes high aspect ratio silicon etching, insulation liner deposition, and seamless metal filling. The desired etch profile should be straightforward, but high aspect ratio silicon etching is still a challenge. In this paper, we investigate the use of etch hard mask for finer TSVs etching to have clear definition of etched via pattern. Conventionally employed photoresist methods were initially evaluated as reference processes, and oxide and metal hard mask were investigated. We admit that pure metal mask is rarely employed in industry, but the etch result of metal mask support why hard mask are more realistic for finer TSV etching than conventional photoresist and oxide mask.