• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.3
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• pp.255-259
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• 2008

Built-in voltage in ITO/$Alq_3$/ Al organic light-emitting diodes was studied by varying a thickness of $Alq_3$ layer using modulated photocurrent technique at ambient condition. A thickness of the $Alq_3$ layer was varied from 100 to 250 nm. From the bias voltage-dependent photocurrent, built-in voltage of the device was able to be determined. The obtained built-in voltage is about 0.8 V irrespective of the $Alq_3$ layer thickness in the device. This value of built-in voltage confirms that the built-in voltage is generated due to a difference of work function of the anode and cathode. The $Alq_3$ layer thickness independent built-in voltage indicates that the built-in electric field in the device is uniform across the organic layer.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.04b
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• pp.14-16
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• 2008

Built-in voltage in organic light-emitting diodes was studied using modulated photocurrent technique ambient conditions. From the bias voltage-dependent photocurrent, built-in voltage of the device is determined. The applied bias voltage when the magnitude of modulated photocurrent is zero corresponds to a built-in voltage. Built-in voltage in the device is generated due to a difference of work function of the anode and cathode. A device was made with a structure of anode/$Alq_3$/cathode to study a built-in voltage. ITO was used as an anode, and Al and LiAl were used as a cathode. A layer thickness of Al and LiAl were 100nm. Obtained built-in voltage is about 1.0V in the Al layer was used as a cathode. The obatined built-in voltage is about 1.6V in the LiAl layer was used as a cathode. The result of built-in voltage is dependent of cathode. We can see that the built-in voltage increase up to 0.4V when the LiAl layer was used as the cathode. These results correspond to the work function of LiAl which is lower than that of Al. As a result, the barrier height for an electron injection from the cathode to the organic layer could be lowered when the LiAl was used as a cathode.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.31-32
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• 2007

Built-in voltage in organic light-emitting diodes was studied using modulated photocurrent technique ambient conditions. A device was made with a structure of anode/$Alq_3$/cathode to study a built-in voltage. An ITO was used as an anode, and $Li_2O$/Al was used as a cathode. From the bias voltage-dependent photocurrent, built-in voltage of the device is determined. The applied bias voltage when the magnitude of modulated photocurrent is zero corresponds to a built-in voltage. Built-in voltage in the device is generated due to a difference of work function of the anode and cathode. It was found that for 0.5nm thick $Li_2O$ layer built-in voltage is the higher than the others. It indicates that a very thin alkaline metal compound $Li_2O$ lowers an electron barrier height.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.51-52
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• 2007

Built-in voltage in organic light-emitting diodes was studied using modulated photocurrent technique ambient conditions. From the bias voltage-dependent photocurrent, built-in voltage of the device is determined. The applied bias voltage when the magnitude of modulated photo current is zero corresponds to a built-in voltage. Built-in voltage in the device is generated due to a difference of work function of the anode and cathode. A device was made with a structure of anode/$Alq_3$/cathode to study a built-in voltage. ITO and ITO/PEDOT:PSS were used as an anode, and Al and LiF/AI were used as a cathode. It was found that an incorporation of PEDOT:PSS layer between the ITO and $Alq_3$ increases a built-in voltage by about 0.4V. This is consistent to a difference of a highest occupied energy states of ITO and PEDOT:PSS. This implies that a use of PEDOT:PSS layer in anode improves the efficiency of the device because of a lowering of anode barrier height. With a use bilayer cathode system LiF/Al, it was found that the built-in voltage increases as the LiF layer thickness increases in the thickness range of 0~1nm. For 1nm thick LiF layer, there is a lowering of electron barrier by about 0.2eV with respect to an Al-only device. It indicates that a very thin alkaline metal compound LiF lowers an electron barrier height.

• Transactions on Electrical and Electronic Materials
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• v.18 no.5
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• pp.257-260
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• 2017

In this paper, we present the design of a 4.5 V low dropout (LDO) voltage regulator implemented in the 130 nm CMOS process. The design uses a two-stage cascaded operational transconductance amplifier (OTA) as an error amplifier, with a body bias technique for reducing dropout voltages. PMOS is used as a pass transistor to ensure stable output voltages. The results show that the proposed LDO regulator has a dropout voltage of 32.06 mV when implemented in the130 nm CMOS process. The power dissipation is only 1.3593 mW and the proposed circuit operates under an input voltage of 5V with an active area of $703{\mu}m^2$, ensuring that the proposed circuit is suitable for low-power applications.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.2
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• pp.120-125
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• 2011

SPDs are increasingly being used against lightning and switching surge according to the applicable revised standard and equipotential grounding system. SPDs are equipped usually with a MOV voltage regulating element. The MOV, however, always is exposed to the danger of thermal runaway resulting from inrushing temporary overvoltage and deterioration. In this paper, the authors made two prototype SPDs built-in Instantaneous trip device and analyzed their limiting voltage through test of the MOV breakdown. As the result of the analysis, the SPDs built-in Instantaneous trip device was proven to be effective for protecting MOV against thermal runaway and Instantaneous trip device react for limiting voltage is considered that is applicable to SPD.

• Journal of Power Electronics
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• v.15 no.6
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• pp.1628-1639
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• 2015

Line-interactive uninterruptible power supply (UPS) systems are good candidates for providing energy storage within a microgrid. In this paper, a control scheme for a line-interactive UPS system applied in a low-voltage microgrid is presented. It is based on the Q-w and P-E droop control to achieve a seamless transition between grid-connected and stand-alone operation modes. Moreover, a new model for designing the controllers is built in the dq-frame based on the instantaneous power definition. The new-built model takes into account the dynamic performance of the output impedance of the inverter in the dq-frame and can be evaluated in the time domain. Compared to the traditional model based on the instantaneous power definition, the new-built model is more accurate to describe the dynamic performance of the system. Simulation and experimental results obtained with a microgrid consisting of two 40-kW line-interactive UPS systems are given to validate the control strategy of the line-active UPS system and the accuracy of the new-built model.

• Journal of the Korean Society of Safety
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• v.28 no.3
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• pp.51-55
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• 2013

The purpose of this study is to find the causes of malfunctions and defective operation of printed circuit boards(PCBs) built into home refrigerators to perform power saving functions. This study performed an electrostatic test of a PCB built-in using an Auto Triggering system; lightning and impulse tests using an LSS-15AX; and an impulse test using an INS-400AX. From the analysis of a secondarily developed product, it was found that electrostatic discharge(ESD) caused more malfunctions and defective operations than electric overstress(EOS) due to overvoltage. As a result of increasing the condenser capacity of the PCB circuit, withstanding voltage was increased to 7.4 kV. In addition, this study changed the power saving mode and connected a varistor to the #2 pin of an IC chip. As a result, the system consisting of all specimens of a finally developed product was operated stably with an applied voltage of less than 10 kV. This study found it necessary to perform quality control at the manufacturing stage in order to reduce the occurrence of electrostatic accidents to IC chips built into a PCB.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.3 s.96
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• pp.18-24
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• 1999

ThisPaper investigates the feasibility of using acoustic emission signal analysis for the detection of built-up edge during machining. Experiments were conducted on a CNC-lathe using conventional carbide insert tools under various cutting conditions. The cutting forces were also measured for comparisons. Experimental evidence is presented which indicates that the presence of a built-up edge can significantly affect the generation of acoustic emission in metal cutting. It is shown that under conditions in which a built-up edge is generated, the variation of $AE_{rms}$ signal with cutting speed can be quite different from the generally accepted linear, monotonic increase as previously reported. The feasibility of utilizing $AE_{rms}$ in built-up edge sensing is suggested.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.5
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• pp.1089-1095
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• 2005

This paper presents a new low-cost Built-In Self-Test (BIST) circuit for 50Hz low noise amplifier (LNA). The BIST circuit is designed for system-on-chip (SoC) transceiver environment. The proposed BIST circuit measures the LNA specifications such as input impedance, voltage gaih, noise figure, and input return loss all in a single SoC environment.