• Journal of Sensor Science and Technology
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• v.28 no.5
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• pp.329-333
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• 2019

Solution-processed oxide thin-film transistors (TFTs) have garnered great attention, owing to their many advantages, such as low-cost, large area available for fabrication, mechanical flexibility, and optical transparency. Negative bias stress (NBS)-induced instability of sol-gel IGZO TFTs is one of the biggest concerns arising in practical applications. Thus, understanding the bias stress effect on the electrical properties of sol-gel IGZO TFTs and proposing an effective recovery method for negative bias stressed TFTs is required. In this study, we investigated the variation of transfer characteristics and the corresponding electrical parameters of sol-gel IGZO TFTs caused by NBS and positive bias recovery (PBR). Furthermore, we proposed an effective PBR method for the recovery of negative bias stressed sol-gel IGZO TFTs. The threshold voltage and field-effect mobility were affected by NBS and PBR, while current on/off ratio and sub-threshold swing were not significantly affected. The transfer characteristic of negative bias stressed IGZO TFTs increased in the positive direction after applying PBR with a negative drain voltage, compared to PBR with a positive drain voltage or a drain voltage of 0 V. These results are expected to contribute to the reduction of recovery time of negative bias stressed sol-gel IGZO TFTs.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.158.4-158
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• 2001

This paper presents a novel circuit configuration for realizing the continuous-time active-only voltage-mode integrator. The proposed integrator consists only of internally compensated type operational amplifier (OA) and operational transconductance amplifiers (OTAs). Since no external passive elements are required, the integrator is suitable for integrated circuit implementation in either bipolar or CMOS technologies. Moreover, the integrator gain can be electronically tuned by adjusting the bias currents of the OTAs. The characteristics of the proposed integrator and the effectiveness of the design procedure in realizing various analog transfer functions have been examined by PSPICE simulation.

• Journal of the Korean Institute of Telematics and Electronics
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• v.6 no.1
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• pp.19-22
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• 1969

Detailed analysis has been developed concerning the transfer function and stability condition of the logarithmic amplifier using a common emitter transistor as a feed-back element. The analysis shows that input current vs output voltage transfer characteristics is accurately ogarithmic through entire operating current, and the time constant depends on input capcitance and collector-emitter equivalent resistance. Also the minimum value of imput capacitance required to stabilize the system is derived.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.391-394
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• 1999

Until now, there is no report for the relationship between the condition of addressing and the characteristics of surface discharge in ac-PDP. We have known that such these experiment was important to drive ac PDP Therefore, this paper deals with the probability of transfer and the character of luminance according to addressing voltage(Va) and blocking voltage(Vg) in addressing period and sustain voltage in sustaining period and we use waveform according to ADS(Address and Display period Separation) method

• Journal of the Korean Vacuum Society
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• v.5 no.1
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• pp.85-92
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• 1996

The external electricla characteristics of helicon wave plasmas were measured over a wide range of RF power and magnetic filed. External parameters. such as antenna voltage , current, phase shift, and interanl parameter, electron density were measured at 7MHz, 1mTorr Ar discharge . The equivalent discharge resistance and reactance, and the power transfer efficiency were calculated through these measurements. There are a helicon mode which produces high density plasma by helicon wave and a lowmode which produces low density plasma by capaictive electric field. In case of the helicon mode, the anternna voltage and current were lower than those of the low-mode. The phase difference between voltage and current decreased suddenly at the transition point from the low-mode to the helicon mode. Equivalent resistance and power efficiency increased and reactance decreased suddenly at the transition point. These results mean that the power transperred to plasma and the nutual coupling between the antenna and plasma increase as the mode changes from the low-mode to the helicon mode.

• The Transactions of the Korean Institute of Power Electronics
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• v.27 no.2
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• pp.106-117
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• 2022

Multiple output converters can be utilized when various output voltages are required in applications. Recently, one of the multiple output converters called fly-buck has been proposed, and has attracted attention due to the advantage that multiple output can be easily obtained with a simple structure. When constant on-time (COT) control is applied, the output ripple voltage must be treated carefully for control stability and voltage regulation characteristics in consideration of the inherent energy transfer characteristics of the fly-buck converter. This study analyzes the operation principle of the fly-buck converter with a ripple generation network and presents the design guideline for the improved output voltage regulation. Validity of the analysis and design guideline is verified using a 5 W prototype of the COT controlled fly-buck converter with a ripple generation network for telecommunication auxiliary power supply.

• Proceedings of the IEEK Conference
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• 2000.11b
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• pp.37-40
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• 2000

This paper has been studied on characteristics of organic light-emitting device with various cathode materials. These catode materials were Al：Li(5%), Al, Cu, CsF/Al. And in these devices, HTL(hole transfer layer) was TPD and EML(emitting layer) was Alq$\sub$3/. We studied the I-V characteristics for each device. And then, the turn-on voltage of device for Al-Li(5%), Al, Cu, CsF/Al cathode were 7, 9, 13, 3V respectively. So, the CsF/Al cathode is superior to other cathode materials for I-V characteristics.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.6
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• pp.85-93
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• 1997

This paper analyzes the steady-state and dynamic characteristics of the watkings-johnson converter. the major contributions of this paper includ identification of the following characteristics unique to the watkins-johnson converter: (1) The output voltage of the converter is nearly constant at the continous conduction mode (CCM), and at discontinousou conduction mode (DCM) it decreses linerly as the output curretn increases. (2) The control-to-output transfer function is a second-order one with a left-half-plane (LHP) zero determined by the combination of the output capacitor and equivalent series resistor of the converter. This LHP zero signinificantly improves the stability of the converter. (3) The control-to-output transfer function reduces to a first-order one, as the converter moves from CCM to DCM. (4) The parastic resistance of the inductor does not cause any significant influence on poles and zeros of the transfer function.

• Journal of Welding and Joining
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• v.19 no.6
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• pp.630-635
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• 2001

The characteristics of spatter generation in the short circuit transfer region of $CO_2$ welding was investigated. Spatteriing phenomena could be classified into three types : Type I generated due to the abrupt increase of arc voltage in arcing duration. Type II by the gas ejection from molten metal and Type III generated by the arc instability at the moment of arc re-ignition just after short circuiting. Main observed types were dependent on the chemical composition of welding wires. The case of YCW12 wires was mainly composed of spatters generated by Type l and Type II, while most, spatters in YCW11 wires were generated by Type II and Type III.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.2
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• pp.118-124
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• 1998

This paper describes a relationship of a space vector PWM and a sinusoidal PWM and presents that the space vector PWM can produce linearly the output voltage to the unity MI(modulation index). At first, reference angles and holding angles are derived from expanding a Fourier series of the reference voltage waveform and then the angles are used for the inverter switching to linearize transfer characteristics of the inverter. In addition, the harmonic components of the output voltage are analyzed and on-line control is shown to be feasible by approximating in piecewise-linearization the reference and holding angles versus the MI. In V/f control of the induction motor, it is verified by the experiment that the motor current is changed smoothly for the variation of the inverter input voltage and the change of the reference voltage.