• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.12
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• pp.2905-2910
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• 2015

CW Radar Sensors can be categorized into Single and Dual by its IF output type. Dual IF type is used for detecting the direction of moving objects. However, Dual IF type has more complicated circuitry than Single IF type and higher cost due to more parts required. In this paper, we propose an algorithm for Single IF type CW radar sensors to detect the direction of moving objects. It performs FFT on signals created at IF output when an object moves and determines approach, stop and recede according to amplitude variations. In order to verify the algorithm, a function generator is used to create a virtual signal and confirmed that it accurately detects the directions according to amplitude variations.

• Journal of electromagnetic engineering and science
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• v.4 no.4
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• pp.143-149
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• 2004

This paper describes characteristics of the single-balanced low IF resistive FET mixer for the digital beam forming(DBF) receiver. This DBF receiver based on the direct conversion method is designed with Low IF I and Q channel. A radio frequency(RF), a local oscillator(LO) and an intermediate frequency(IF) considered in this research are 1950 MHz, 1940 MHz and 10 MHz, respectively. Super low noise HJ FET of NE3210S01 is considered in design. The measured results of the proposed mixer are observed IF output power of -22.8 dBm without spurious signal at 10 MHz, conversion loss of -12.8 dB, isolation characteristics of -20 dB below, 1 dB gain compression point(PldB) of -3.9 dBm, input third order intercept point(IIP3) of 20 dBm, output third order intercept point(OIP3) of 4 dBm and dynamic range of 30 dBm. The proposed mixer has 1.0 dB higher IIP3 than previously published single-balanced resistive and GaAs FET mixers, and has 3.0 dB higher IIP3 and 4.3 dB higher PldB than CMOS mixers. This mixer was fabricated on 0.7874 mm thick microstrip $substrate(\varepsilon_r=2.5)$ and the total size is $123.1\;mm\times107.6\;mm$.

• Journal of the Optical Society of Korea
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• v.19 no.3
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• pp.255-259
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• 2015

We have proposed and experimentally verified a pulse-width modulation (PWM) generator which directly generated a PWM signal in the optical domain. Output waveforms were clear at the repetition rate of 16 MHz; the duty cycle (DC) was from 14.7% to 72.1%; and the DC-control resolution was about 4.399%/dB. The PWM generator' operation principle is based on the injection-locking property of a single-mode Fabry-$P{\acute{e}}rot$ laser diode (SMFP-LD). The SMFP-LD, which has a self-locked mode wavelength at ${\lambda}_{PWM}$, was used to detect the power of the injection-locking signal (optical analog input). If the analog input power is high, the SMFP-LD is locked to the wavelength of the input signal ${\lambda}_a$ and there is no output after an optical bandpass filter (OBF). If the analog input power is low, the SMFP-LD is unlocked and there is output signal at ${\lambda}_{PWM}$ after the OBF. Thus, the SMFP-LD plus the OBF provide digital output for an analog input. The DC of the output PWM signal can be controlled by tuning the power of the analog input.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.4-7
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• 1997

When we use Hadamard transform spectrometers (HTS), we can increase signal to noise ratio(SNR) by multiplexing which is done by masks. But if the mask has a single defective element, output-SNR decreases. In this paper the effect of a single defective element on the output-SNR is investigated. And a method of compensating for the defective mask element is presented.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.39 no.5
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• pp.1-7
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• 2002

In this paper, an extended type of a direct learning control(DLC) method is proposed for the effective control of systems which perform a given task repetitively. DLC methods have been suggested to overcome the defects of iterative learning control, the learning process should be resumed from the beginning even if a slight change occurs in the desired output pattern. If a given desired output trajectory is "proportional" to the output trajectories which are learned previously, we can obtain the desired control input directly without the iterative learning process by using the DLC. First, most existing DLC methods are shown to be applicable only to single-input single-output systems with the relative degree one and then, an extended type of DLC is proposed for a class of nonlinear systems having the relative degree more than or equal to one by using the known relative degree of a nonlinear system. By the simulation results for the arbitrary nonlinear system with the relative degree more than one, the validity and the performance of the proposed DLC method are examined.

• Progress in Superconductivity
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• v.5 no.1
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• pp.17-20
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• 2003

We have designed and measured a SFQ(Single Flux Quantum) DFFC and an Inverter(NOT) for superconducting ALU(Arithmetic Logic Unit) development. To optimize the circuit, we used Julia, XIC, and L meter for circuit simulations and circuit layouts. The Inverter was consisted of a D Flip-Flop, a data input, a clock input and a data output. If a data pulse arrives at the inverter, then the output reads ‘0’ (no output pulse is produced) at the next clock period. If there is no input data pulse, it reads out ‘1’(output pulse is produced). The DFFC was consisted of a D flip-Flop, an Inverter, a Data in, a Clock in and two outputs. If a data pulse arrives at the DFFC circuit, then the output2 reads ‘1’ at the next clock period, otherwise it reads out ‘1’ to output1. Operation of the fabricated chip was performed at the liquid helium temperature and at the frequencies of 1KHz.

• Proceedings of the KIEE Conference
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• 2007.04a
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• pp.110-112
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• 2007

Output voltage waves of a DC/AC inverter system are likely to be distorted if variable loads e.g. motors or rectifiers exist in the output terminal. This paper designs a disturbance observer-based PI controller for a single-phase inverter system that is robust against load changes. In this paper, we regard the output voltage changes due to various loads as disturbances of the control system, Then we design a disturbance observer for estimation of the disturbances caused by the load current and any other error sources (such as parameter uncertainties and model mismatches etc.). In order to test the performance of the proposed control law, simulation studies are carried out for a single-phase inverter system using SimPowerSystems of Matlab Simulink. Compared to a simple PI control, the disturbance observer-based controller shows enhanced performance in transient responses for step load changes.

• JSTS:Journal of Semiconductor Technology and Science
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• v.2 no.1
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• pp.7-18
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• 2002

Single-ended differential RF circuit topologies fully utilizing complementary characteristics of both NMOS and PMOS are proposed, which have inherent advantage of both single-ended and differential circuits. Using this concept, we propose a CCPP (Complementary CMOS parallel push-pull) amplifier which has single-ended input/output with differential amplifying characteristics, leading to more than 30 dB improvement on $IIP_2$. In addition, complementary resistive mixer is also proposed, which provides not only differential IF outputs from single-ended RF input, but much better linearity as well as isolation characteristics. Experimental results using $0.35{\;}\mu\textrm{m}$ CMOS process show that, compared with conventional NMOS resistive mixer, the proposed mixer shows 15 dB better LO-to-IF isolation, 4.6 dB better $IIP_2$, and 4.5 dB better $IIP_3$performances.

• Bulletin of the Korean Chemical Society
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• v.24 no.3
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• pp.279-284
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• 2003

The One Pass Method (OPM) previously presented for the identification of single input single output systems is used to estimate the parameters of a Decentralized Control System (DCS). The OPM is a linear and therefore a simple estimation method. All of the calculations are performed in one pass, and no initial parameter guess, iteration, or powerful search methods are required. These features are of interest especially when the parameters of multi input-output model are estimated. The benefits of the OPM are revealed by comparing its results against those of two recently published methods based on pulse testing. The comparison is performed using two databases from the literature. These databases include single and multi input-output process transfer functions and relevant disturbances. The closed loop responses of these processes are roughly captured by the previous methods, whereas the OPM gives much more accurate results. If the parameters of a DCS are estimated, the OPM yields the same results in multi or single structure implementation. This is a novel feature, which indicates that the OPM is a convenient and practice method for the parameter estimation of multivariable DCSs.

• Proceedings of the KIEE Conference
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• 1998.07b
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• pp.647-649
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• 1998

This paper describes a robust stabilization of single input nonlinear systems with parametric uncertainty. We first investigate differential flatness of the nominal nonlinear systems. If a single input system is differentially flat, it possesses a flat output. And we define coordinate transformation functions via successively differentiating the flat output, and we also consider the robust fictitious controls at every differentiation of the flat output. In the new coordinates the nonlinear system is transformed into the Brunovsky normal form with matched uncertainty. With a robust control based on the Lyapunov method, the robust stabilization is achieved.