• Journal of electromagnetic engineering and science
• /
• 제10권3호
• /
• pp.132-137
• /
• 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
• /
• 제7권1호
• /
• pp.28-35
• /
• 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.

• 한국전자통신학회논문지
• /
• 제15권5호
• /
• pp.835-840
• /
• 2020

본 논문은 수십시간이 소요되는 총복사전력(TRP) 측정 시간을 단축하는 방안을 컴퓨터 모의실험과 실제 실험을 통하여 검증한 결과를 제시하고 있다. 5G의 고주파수 대역에서는 무선통신기기의 정확한 성능평가를 위하여 TRP 측정이 기본적으로 수행되지만 촘촘한 샘플링 간격 때문으로 인하여, 긴 측정 시간이 소요되는 문제점을 가지고 있다. 더구나 다양한 빔 형성 시나리오를 갖는 경우 전체 측정 시간은 기하급수적으로 증가한다. 따라서, TRP 측정 시간 단축 방안이 필요하며, 그 일환으로 본 논문에서는 유효등방복사전력(EIRP)과 TRP 관계식을 이용하여 측정시간을 단축하는 방법을 다루었다. 먼저 TRP와 EIRP의 관계식을 관찰하고, 피시험용 안테나의 설계 및 제작하였으며 모의실험 결과와 측정결과를 통한 오차를 분석하였다. 그 결과 EIRP를 통하여 TRP를 산출한 결과는 매우 작은 오차를 가짐을 확인하였다. 본 방법은 향후 5G 무선통신기기의 TRP 도출에 적용할 수 있을 것으로 예상한다.

• 한국전자파학회논문지
• /
• 제17권3호
• /
• pp.272-279
• /
• 2006

본 논문에서는 W-CDMA(Wide band Code Division Multiple Access) 시스템에서 채널 측정 및 프레임 동기 확인에 사용되는 파일럿 비트 패턴의 프레임 동기 단어(frame synchronization words) 성능을 분석한다. 또한 W-CDMA 시스템에서는 두 개의 수신 단말기를 갖지 않고도, 다른 주파수의 측정을 하기 위해 압축 모드(compressed mode)를 사용한다. 제안된 프레임 동기용 이원 부호의 우선 쌍 간의 보완 매핑(complementary mapping) 관계를 이용하면, 압축 모드에서도 프레임 동기 특성을 유지함을 컴퓨터 시뮬레이션을 통하여 확인한다. 검출 확률과 오 경보 확률을 갖는 수신기 동작 특성(ROC: Reciever Operating Characteristic) 곡선은 LLRT(Log Likely-hood Ratio Test), GLRT(Generalied Likeiyhood Ratio Test), 연판정(soft correlation test), 경 판정(hard correlarion test)과 같은 다양한 검출법(detection metrics)을 이용하여 레일레이 페이딩 채널에서 제안된 프레임 동기 단어의 성능 분석에 사용된다. 이 논문의 파일럿 비트 패턴의 성능에 대한 연구 결과는 3세대 W-CDMA 시스템에서 프레임 동기의 설계 및 구현에 유용한 참고 자료가 될 수 있을 것이다.

• 로봇학회논문지
• /
• 제12권3호
• /
• pp.350-355
• /
• 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.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2004년도 하계학술대회 논문집 C
• /
• pp.1658-1660
• /
• 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.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2003년도 하계종합학술대회 논문집 V
• /
• pp.2753-2756
• /
• 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.

• 소음진동
• /
• 제7권6호
• /
• pp.1007-1013
• /
• 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.

• 전기학회논문지P
• /
• 제64권3호
• /
• pp.116-120
• /
• 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.

• 한국광학회:학술대회논문집
• /
• 한국광학회 2000년도 제11회 정기총회 및 00년 동계학술발표회 논문집
• /
• pp.258-259
• /
• 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)