• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.6
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• pp.35-42
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• 2010

This paper describes a 10 bit 80MHz CMOS D/A converter for wireless communication system. The proposed circuit in the paper is implemented with a $0.18{\mu}m$ CMOS n-well 1-poly 6-metal process. The architecture of the circuit consists of the 4bit LSB with binary decoder, and both the 3bit ULSB and the 3bit MSB with the thermometer decoder. The measurement results demonstrates SFDR of 60.42dBc at sampling frequency 80MHz, input frequency 1MHz and ENOB of 8.75bit. INL and DNL have been measured to be ${\pm}$0.38LSB and ${\pm}$0.32LSB and glitch energy is measured to be 4.6$pV{\cdot}s$. Total power dissipation is 48mW at 80MHz(maximum sampling frequency) with a single power supply of 1.8V.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.2
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• pp.1-6
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• 2002

In this paper, an Analog Flat Panel interface(AFPI) which supports for UXGa(Ultar extended Graphics Array)-Compatible TFT LCD Driver is designed. The Proposed AFPI is composed of 8-b ADC, Automatic Gain Control(AGC), Low-Jitter PLL. In order to obtain a high speed and low power consumption, an efficient architecture of 8-bit ADC is proposed, whose FR(Folding Rate) is 8, NFB(Number of Folding Block) is 2, and IR (Interpolating Rate) is 16. We can get high SNDR by adopting distributed track and hold circuits. Also a programmable AGC which is possible to control gain and clamp, and a low-jitter PLL are proposed. The chip has been fabricated with 0.25${\mu}{\textrm}{m}$ 1-poly S-metal n-well CMOS technology. The effective chip area is 3.6mm $\times$ 3.2mm and it dissipates about 602㎽ at 2.5V power supply. The INL and DNL are within $\pm$ 1LSB. The measured SNDR is about 43㏈, when the input frequency is 10MHz at 200MHz clock frequency.

• Journal of KSNVE
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• v.5 no.4
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• pp.543-553
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• 1995

Modern steam turbine generators are being built as a higher power and larger system, experiencing more frequent starts and stops of operation due to a constant change of power demands. Hence, they are inevitably more vulnerable to various vibrations, and more often exposed to the danger of sudden vibration accidents than ever before. Even under the circumstances, in order to secure the system reliability of steampower plants and there by to supply safely the public electricity, it is important to prevent a sudden vibration accident in one hand and even when it happens, to raise an operating efficiency of the plants throught swift and precise treatments in the other. In this study, an interactive vibration diagnostic system has been developed to make the on-site vibration diagnosis of steam turbine generators possible and convenient, utilizing a note-book PC. For this purpose, at first the principal vibration phenomena, such as various unbalance and unstable vibrations as well as rubbing, misalignment, and shaft crack vibrations, have been systematically classified as grouped parameters of vibration frequencies, amplitudes, phases, rotating speeds at the time of accident, and operating conditions or condition changes. A new complex vibration diagnostic table has been constructed from the causal relations between the characteristic parameters and the principal vibration phenomena. Then, the diagnostic system has been developed to screen and issue the corresponding vibration phenomena by assigning to each user-selected combination of characteristic parameters a unique characteristic vector and comparing this vector with a diagnostic vector of each vibration phenomenon based on the constructed diagnostic table. Moreover, the diagnostic system has a logic whose diagnosis may be performed successfully by inputing only some of the corresponding characteristic parameters without having to input all the parameters. The developed diagnostic system has been applied to perform the diagnosis of several real cases of steam turbine vibration accidents. And the results have been quite satisfactory.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.7 s.337
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• pp.21-26
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• 2005

An area efficient, low power switch-matrix semidigital FIR reconstruction filter for delta-sigma D/A converter is proposed. Filter coefficients are quantified to 7-bit and 7 current sources that correspond to each coefficient bit are used. The proposed semidigital FIR reconstruction filter is designed in a 0.25 um CMOS process and incorporates 1.5 mm$^{2}$ of active area and a power consumption is 3.8 mW at 2.5 V supply. The number of switching transistors is 1419 at 205 filter order. Simulation results show that the filter output has a dynamic range of 104 dB and 84 dB attenuation of out-of-band quantization noise.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.5
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• pp.99-105
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• 2014

A reference spur suppressed PLL with two-symmetrical loops without changing the bandwidth which is optimized to suppress phase noise and reduce locking time has been designed. The principle of suppressing a reference signal spur is to stabilize the input voltage of voltage controlled oscillator (VCO). The proposed PLL consists of a phase-frequency detector(PFD) which has two outputs, two charge pumps(CP), two loop filters(LF), a divider and a VCO which has two inputs. Simulation results with $0.18{\mu}m$ CMOS process show that the reference spur is approximately suppressed to 1/2 of the reference spur in a conventional PLL. Even though there is a 5% process variation in the magnitude of R and C, the simulation result shows that the reference spur is still suppressed to 1/2 of the reference spur in a conventional PLL. The power consumption is 6.3mW at the power supply of 1.8V.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.8 s.338
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• pp.53-60
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• 2005

Recently, sub-micron CMOS technologies have taken the place of III-V materials in a number of areas in integrated circuit designs, in particular even for the applications of gjgabit optical communication applications due to its low cost, high integration level, low power dissipation, and short turn-around time characteristics. In this paper, a four-channel transimpedance amplifier (TIA) array is realized in a standard 0.35mm CMOS technology Each channel includes an optical PIN photodiode and a TIA incorporating the fully differential regulated cascode (RGC) input configuration to achieve effectively enhanced transconductance(gm) and also exploiting the inductive peaking technique to extend the bandwidth. Post-layout simulations show that each TIA demonstrates the mid-band transimpedance gain of 59.3dBW, the -3dB bandwidth of 2.45GHz for 0.5pF photodiode capacitance, and the average noise current spectral density of 18.4pA/sqrt(Hz). The TIA array dissipates 92mw p in total from a single 3.3V supply The four-channel RGC TIA array is suitable for low-power, high-speed optical interconnect applications.

• Journal of Convergence for Information Technology
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• v.10 no.6
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• pp.41-48
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• 2020

The sensor nodes in underwater IoT networks have practical limitations in power supply. Thus, the reduction of power consumption is one of the most important issues in underwater environments. In this regard, AMC(Adaptive Modulation and Coding) techniques are used by using the relation between SNR and BER. However, according to our hands-on experience, we observed that the relation between SNR and BER is not that tight in underwater environments. Therefore, we propose a deep learning based MLP classification model to reflect multiple underwater channel parameters at the same time. It correctly predicts BER with a high accuracy of 85.2%. The proposed model can choose the best parameters to have the highest throughput. Simulation results show that the throughput can be enhanced by 4.4 times higher than the conventionally measured results.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.4
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• pp.298-308
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• 2017

This paper presents a Interleaved Buck Converter(IBC) system with Random PWM to reduce electromagnetic noise by harmonics. Swithced mode power supply generally controlled by high switching frequency have a electromagnetic interference(EMI) issue due to the high-voltage/high-current switching to regulate the voltage in buck converter. To solve the problem. we present a novel IBC system with PRBS. IBC system has two active switches with 180 phase difference that controll the cicuit with two PWM signal. IBC system may be disadventageous for the cost due to the addtion of one set of switch, but it has adventages of power distribution, current ripple cancellation, fast transient response, and passive component size reduction. To verify the validity of study, simulation program has been bulit using PSIM and the experimental results of IBC system using RPWM was compared with the conventinal PWM and randomized PWM.

• Journal of Navigation and Port Research
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• v.26 no.5
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• pp.525-528
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• 2002

The proposed EMC filter composed with feed-through capacitors and ferrite beads of high permeability was prepared which satisfy the EMC standard for a wide-band noise signal in the frequence of 10 MHz to 1.5 GHz in power supply line. The optimum structure of ferrite bead was found by calculating the load effect of ferrite beads. As a result, the filter showed excellent differential- and common-mode noises filtering characteristics above 30dB in the frequency band from 10 MHz to 1.5 GHz. The immunity characteristics are improved more than 10 to 30 dB over the frequency band from DC to 1.8GHz.

• Journal of Power Electronics
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• v.11 no.3
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• pp.294-303
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• 2011

In this paper an effective five-phase induction motor (IM) and its drive methods are proposed. Due to the additional degrees of freedom, the five-phase IM drive presents unique characteristics for enhancing the torque producing capability of the motor. Also the five-phase motor drives possess many other advantages when compared to traditional three-phase motor drives. Some of these advantages include, reducing the amplitude and increasing the frequency of the torque pulsation, reducing the amplitude of the current without increasing the voltage per phase and increasing the reliability. In order to maximize the torque per ampere, the proposed motor has concentrated winding, the produced back electromotive force (EMF) is almost trapezoidal, and the motor is supplied with the combined sinusoidal plus the third harmonic of the currents. For demonstrating the superior performance of the proposed five-phase IM, the motors are also analyzed on the synchronously rotating reference frame. To supply trapezoidal current waveform and to exclude the effect of the $3^{rd}$ harmonic current, a new control stratagem is proposed. The proposed control method is based on direct torque control (DTC) and rotor flux oriented control (RFOC) of the five-phase IM drives. It is able to reduce the acoustical noise, the torque, the flux, the current, and the speed pulsations during the steady state. The DTC transient merits are preserved, while a better quality steady-state performance is produced in the five phase motor drive for a wide speed range. Experimental results clearly demonstrated a more dynamic steady state performance with the proposed control system.