• Journal of electromagnetic engineering and science
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• v.10 no.3
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• pp.132-137
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• 2010

We present results of room-temperature characterization of lithographically manufactured antenna-coupled NbN micro-bolometers. The bolometers are assembled together with a hyper-hemispherical Si lens to couple the incident radiation to the bolometer from the back-side of the substrate. The bolometers are designed to operate at 300~1,000 GHz and they are characterized at 321~782 GHz. Radiation patterns are measured at 321 GHz, 400 GHz, 654 GHz, and at 782 GHz. The frequency dependency of the beamwidth is studied with several azimuthal beam profile measurements at 321~500 GHz.

• JSTS:Journal of Semiconductor Technology and Science
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• v.7 no.1
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• pp.28-35
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• 2007

This paper presents a high-speed flash analog-to-digital converter (ADC) for ultra wide band (UWB) receivers. In this flash ADC, the interpolating technique is adopted to reduce the number of the amplifiers and a linear and wide-bandwidth interpolating amplifier is presented. For this ADC, the transistor size for the cascaded stages is inversely scaled to improve the trade-off in bandwidth and power consumption. The active inductor peaking technique is also employed in the pre-amplifiers of comparators and the track-and-hold circuit to enhance the bandwidth. Furthermore, a digital-to-analog converter (DAC) is embedded for the sake of measurements. This chip has been fabricated in $0.13{\mu}m$ 1P8M CMOS process and the total power consumption is 113mW with 1V supply voltage. The ADC achieves 4-bit effective number of bits (ENOB) for input signal of 200MHz at 5-GSample/sec.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.5
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• pp.835-840
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• 2020

In this paper, we described the verification results on method by using the computer simulation and practical experiment for reduction of total radiated power (TRP) measurement time consuming tens of hours. TRP measurements are used in the 5G band in order to exactly evaluate the wireless communication equipment, but it takes a long measurement time because of dense sampling interval. Moreover, if there are various beam forming scenarios, the total measurement time increases exponentially. Therefore, the world-wide research on reduction method of the TRP measurement time is intensively on going. The verified method in this paper is to calculate the TRP through effective isotropical radiated power (EIRP). At first, the relation of TRP and EIRP was investigated, and an antenna for testing was designed and constructed. And, the amount of error was analyzed through simulation and measurement. The analysed results showed that the derived TRP through EIRP has very small error. This method could be applied for TRP measurements of 5G wireless communication equipments.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.3 s.106
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• pp.272-279
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• 2006

In this paper, we evaluate the performance of frame synchronization words of pilot bit patterns which are used for the channel estimation and frame synchronization confirmation in W-CDMA(Wide band Code Division Multiple Access) system. W-CDMA system also uses compressed mode to make measurements from another frequency without a full dual receiver terminal. It is confirmed by using computer simulation that the proposed frame synchronization words also maintain the frame synchronization property in the compressed mode by using the complementary mapping relationship of preferred pair ROC(Receiver Operating Characteristic) curves with probability of detection and false alarm are used to analized the performance of the proposed frame synchronization words by using the various detection metrics such as LLRT(Log Likelyhood Ratio Test), GLRT(Generalied Likelyhood Ratio Test), soft and hard correlation tests in AWGN and Rayleigh fading channels. It is expected that the research results fer the performance of pilot bit patterns of this paper can be useful reference for the design and implementation of frame synchronization in 3rd generation W-CDMA system.

• The Journal of Korea Robotics Society
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• v.12 no.3
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• pp.350-355
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• 2017

UWB (Ultra Wide Band) refers to a system with a bandwidth of over 500 MHz or a bandwidth of 20% of the center frequency. It is robust against channel fading and has a wide signal bandwidth. Using the IR-UWB based ranging system, it is possible to obtain decimeter-level ranging accuracy. Furthermore, IR-UWB system enables acquisition over glass or cement with high resolution. In recent years, IR-UWB-based ranging chipsets have become cheap and popular, and it has become possible to implement positioning systems of several tens of centimeters. The system can be configured as one-way ranging (OWR) positioning system for fast ranging and TWR (two-way ranging) positioning system for cheap and robust ranging. On the other hand, the ranging based positioning system has a limitation on the number of terminals for localization because it takes time to perform a communication procedure to perform ranging. To overcome this problem, code multiplexing and channel multiplexing are performed. However, errors occur in measurement due to interference between channels and code, multipath, and so on. The measurement filtering is used to reduce the measurement error, but more fundamentally, techniques for removing these measurements should be studied. First, the TWR based positioning was analyzed from a stochastic point of view and the effects of outlier measurements were summarized. The positioning algorithm for analytically identifying and removing single outlier is summarized and extended to three dimensions. Through the simulation, we have verified the algorithm to detect and remove single outliers.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1658-1660
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• 2004

Use of higher voltage and higher capacity of power systems and their equipment is leading to an increase in the size of the entire system. In order to reduce the cost of constructing a substation, it is necessary to reduce the size of equipment. So, this paper described optical sensor, which exploited the electric and magnetic potentiometer to sense the measured voltage and current of medium voltage GIS. It can be used both in measurement and in protection relays as its well linearity, rapid response, broad dynamic range, wide frequency band, no magnetic saturation, small in volume, light weight, and saft in insulation.

• Proceedings of the IEEK Conference
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• 2003.07c
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• pp.2753-2756
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• 2003

A convenient, tunable loop-gain negative impedance circuit that increases input impedance of a front-end in a bioimpedance measurement has been proposed. Since the proposed circuit comprises wide-band operational amplifiers, selecting operational amplifiers is easy, while an operational amplifier of proper bandwidth should be chosen to use conventional circuit. Also, since loop-gain can be controlled by a feedback resistor connected serially with a feedback capacitor, loop-gain is tunable with a potentiometer. The input impedance of the proposed circuit is two times larger than that of the conventional circuit. Furthermore, closed loop phase response of the proposed circuit is better than that of the conventional circuit or without a negative capacitance circuit. The implemeted, proposed circuit showed stable operation and a zero input capacitance.

• Journal of KSNVE
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• v.7 no.6
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• pp.1007-1013
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• 1997

This paper presents active vibration control scheme of multi-mode forced vibration using piezocetamic sensors and actuators. The control scheme adopted is the Positive Position Feedback (PPF) control. Among various vibration control techniques. PPF control technique makes use of generalized displacement measurements to accomplish the vibration suppression. Two independent controllers are implemented to control the first and the second modes of the beam under external excitation. Experimental results for various damping ratios and feedback gains of the PPF controllers are compared with respect to the contorl efficiency. The results indicate that steady state vibration under wide band excitation can be controlled effectively when multiple sets of PZT sensors and actuators were used with PPF control technique.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.64 no.3
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• pp.116-120
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• 2015

In this paper, a step type driver dipole antenna with a tapered balance and unbalance (balun) by a coplanar waveguide (CPW) to coplanar strip (CPS) transition is proposed. The proposed antenna consisted of step type driver, a CPW to CPS transition and tapered balun. The proposed antenna is realized the multi and wide resonate frequency band to introduce the step type driver and tapered balun. The step type driver is acted as a director too. This antenna could be more easily designed than the conventional printed quasi-Yagi dipole antenna. The operating frequency bandwidth was 650 [MHz] (2.65~3.3 GHz), 900 [MHz] (4.7~5.6 GHz) under a return-loss criterion of less than 10 dB. The measurements of the proposed antenna exhibited good results in the wideband operating frequency and radiation pattern. The proposed antenna can support wireless communications applications.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.258-259
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• 2000

Quantum Well Disordering (QWD) has drawn a considerable attention in recent years$^{(1-3)}$ due to its wide applicability to optoelectronic devices. QWD allows modification of the shape of QW in selected regions, hence it modifies the subband energies in conduction and valance bands$^{(4)}$ . This leads to changes in optical properties such as band gap, absorption coefficient and refractive index. Thus such disordering in selected areas enables monolithic integration of various optoelectronic devices such as lasers, EA/EO modulators, waveguides and optical amplifiers. In this paper, we investigate the quantum well disordering effects on photoluminescence spectra by using experimental measurements and theoretical analysis$^{(5)}$ . (omitted)