• 한국방재안전학회논문집
• /
• 제7권2호
• /
• pp.1-8
• /
• 2014

급경사지 계측에 활용을 위하여 GNSS와 TRS센서를 주축으로 하여 전원, 통신 등의 부대설비, 그리고 변위 추출 및 가시화 등의 데이터처리 소프트웨어를 개발하여 스마트폴 계측시스템을 구축하였다. 본 연구에서 개발한 스마트폴 계측센서의 개념은 GNSS안테나 바로 밑에 TRS센서 및 자이로(gyro) 센서 등, 그리고 하단에 함수비센서를 장착하여 실시간으로 지표변위는 물론, 지반의 병진, 활동, 침하 등의 세가지 요인을 추출해 내고 함수비를 추출하여 전송할 수 있도록 하였다. 스마트폴 계측시스템은 데이터 수신부, 데이터 수집 및 전송부, 데이터 처리부로 구분하여 각 부분별 기능을 발휘할 수 있도록 구축한 다음, 현장적용성 평가를 위해 인위적 변위를 도입한 시험계측을 실시하고 그 결과를 분석하였다.

• 한국전자파학회논문지
• /
• 제29권8호
• /
• pp.632-639
• /
• 2018

본 논문에서는 130 nm 공정을 이용한 Ku-band에서의 송수신 칩을 사용하여 제작된 단일 안테나 모듈을 제안한다. 레이다 수신부에서 DCOC 피드백을 사용한 STC(sensitivity time control)가 거리에 따라 일정한 SNR을 유지한다. 또한 수신부 RF단에서 gain control을 통하여 수신단의 dynamic range를 조절할 수 있다. 칩의 출력 파워는 9 dBm이고, 수신부의 총 이득은 82 dB이다. 단일 안테나에서 Tx 신호가 Rx로 직접 누설되는 것을 막기 위해 stub-tuned hybrid coupler를 사용하였다. 최대 측정거리는 6 m이고, 혼안테나와 금속판을 사용하여 측정하였다.

• 디지털산업정보학회논문지
• /
• 제5권1호
• /
• pp.83-88
• /
• 2009

This paper consider the problem of direction of arrival(DOA) estimation in the presence of multipath propagation. The sensor elements are assumed to be linear and uniformly spaced. Numerous authors have advocated the use of a beamforming preprocessor to facilitate application of high resolution direction finding algorithms The benefits cited include reduced computation, improved performance in environments that include spatially colored noise, and enhanced resolution. Performance benefits typically have been demonstrated via specific example. The purpose of this paper is to provide an analysis of a beamspace version of the MUSIC algorithm applicable to two closely spaced emitters in diverse scenarios. Specifically, the analysis is applicable to uncorrelated far field emitters of any relative power level, confined to a known plane, and observed by an arbitrary array of directional antenna. In this paper, we researched about optimize beam forming to smart antenna system. The covariance matrix obtained using fourth order cumulant function. Simulations illustrate the performance of the techniques.

• Journal of information and communication convergence engineering
• /
• 제6권4호
• /
• pp.391-395
• /
• 2008

Wideband terminal and base station is required to serve not only existing 1st and 2nd generation mobile communication systems but also 3rd generation systems. In this paper, we present a feasibility study on coaxial feed compact wideband antenna for UHF RFID reader application. The original antenna was designed for partial discharge detection sensor in high voltage diagnostic system. However, we modified the original prototype to achieve shifted down resonant frequency for wideband wireless communication applications. The experimental result shows good return loss characteristics and radiation patterns except for the total gain at each resonant frequency. The maximum measured gain was 2.45 dBi$\sim$3.18 dBi at 910MHz.

• Journal of information and communication convergence engineering
• /
• 제6권2호
• /
• pp.164-168
• /
• 2008

Wideband terminal and base station is required to serve not only existing 1st and 2nd generation mobile communication systems but also 3rd generation systems. In this paper, we presents a feasibility study on single feed compact wideband antenna for wireless communication applications including GSM (890-960 MHz), GPS (1575 MHz), DCS (1710-1880 MHz), PCS (1880-1990 MHz), UMTS (1900-2200 MHz), ISM (2400-2480 MHz), IMT2000 and satellite DMB bands. The original antenna was designed for partial discharge detection sensor in high voltage diagnostic system. However, we modified the original prototype to achieve shifted down resonant frequency for wideband wireless communication applications. The experimental result shows good return loss characteristics and radiation patterns except for the total gain at each resonant frequency. The maximum measured gain was 2.45 dBi${\sim}$3.18 dBi at 1710 MHz${\sim}$1880 MHz.

• Smart Structures and Systems
• /
• 제1권3호
• /
• pp.267-282
• /
• 2005

This work describes ongoing development of an embedded sensor system for the early detection and prevention of deterioration of reinforcing steel tendons within reinforced concrete. These devices will evaluate the condition of the steel tendon using ultrasonic techniques and then wirelessly transmit this data to the outside world without human intervention. The ultrasonic transducers and the interpretation of the sensed signals that allow detection and prognosis of tendon condition are detailed. Electrical characterization of concrete mixtures used in bridge construction is conducted and a wideband microstrip antenna is designed and fabricated to operate between 2.4 and 2.5 GHz when embedded in such a medium. Simulations and measurements of the embedded antenna element are presented. Transceiver selection and implementation are discussed as well as future work in operational protocols, sensor networking, and power sources. By implementing commercially available off-the-shelf components whenever possible, these devices have the potential to save millions of dollars a year in evaluation, repair and replacement of reinforced concrete.

• 한국초전도ㆍ저온공학회논문지
• /
• 제24권1호
• /
• pp.29-33
• /
• 2022

Recently, development of a cryogenic fluids storage tank for storing or transporting liquid hydrogen is actively in progress. In cryogenic fluids storage tanks, hydrogen evaporates due to the extreme temperature difference inside and outside the tank. As the mass of the cryogenic fluids changes with continuous vaporization, the fluids level also changes. Therefore, there is need for a method of accurately measuring the level change in the storage tank. In the case of general cryogenic fluids, it is difficult to accurately measure the level because the dielectric constant is very low. As a method of measuring cryogenic fluids level with low dielectric constant, it can be used an Millimeter wave (MM wave) FMCW radar sensor. However, the signal sensitivity is very weak and the level accuracy is poor. In this paper, the signal sensitivity is improved by designing the horn lens antenna of the existing 80 GHz FMCW radar sensor. Horn lens antenna is fabricated by FDM/SLA type 3D printer according to horn and lens characteristics. The horn is used to increase the signal gain and the lens improves the signal straightness. This makes it possible to measure the level of cryogenic fluids with a low dielectric constant.

• 한국통신학회논문지
• /
• 제38C권7호
• /
• pp.643-649
• /
• 2013

본 논문에서는 무선통신기기에서 필수적으로 사용되는 안테나의 근접 전자기장 변화에 의한 반사계수의 변화를 토대로 하여 사람의 심박신호를 검출한다. 반사되는 신호를 검출하기 위하여 20 dB의 directional coupler를 사용하여 송신신호에 영향을 주지 않고 안테나의 반사계수를 검출하는 회로를 사용하였다. 사람의 심박에 의한 다이폴 안테나의 반사계수는 약 0.07 dB 가량 변하게 되어 검출하기 어려우므로, 민감도를 향상시키는 방법을 적용하여 심박신호를 깨끗하게 잡아내었다. Discrete한 소자의 사용으로 오차가 발생하는 것을 감안하여 안테나의 위치를 움직여 최적 지점에서 더 좋은 심박신호의 결과를 나타내는 것을 확인하였고, 일반적인 통신신호에서도 가능한지 확인하기 위하여 4 MHz 대역의 FM신호를 사용하여 잘 동작하는 것을 검증하였다.

• 한국정밀공학회지
• /
• 제29권11호
• /
• pp.1159-1163
• /
• 2012

In this paper, we would like to introduce two dimensional non-contact position sensor by using an electromagnetic induction based coil system and an algorithm to estimate the position of pointer. The sensor which will introduce in this paper is composed of a pointer including LC resonant circuit and a sensor board to detect the electromagnetic signal from the pointer. Because of the simplicity shape of the line antenna, low cost and free form curved shape of the sensor device is possible. In this research, we proposed a new two dimensional non-contact type electromagnetic sensor system and realized the proposed sensor device. From the experiments, the proposed device can be employed for the two dimensional position sensor.

• 한국전자파학회논문지
• /
• 제27권5호
• /
• pp.416-423
• /
• 2016

본 논문은 광대역 시스템에서 이용 가능한 빔 틸트 특성을 가지는 Conformal 구조의 $1{\times}4$패치 어레이 안테나를 설계 및 제작하였다. E자 형태의 패치 안테나 및 L-probe 급전 방식을 이용하여 광대역 단일 패치를 설계하였고, 전방으로 20도의 빔 틸트 특성을 얻기 위해 $1{\times}4$ 안테나 어레이를 T-junction 전력분배기와 42 psec의 마이크로스트립 전송선을 이용하였다. 3.6~4.4 GHz에서 9 dB 이상의 반사 손실이 측정되었으며, 3.75~4.25 GHz에서 10 dBi 이상의 안테나 이득을 가지며, 30도 이하의 HPBW 특성이 측정되었다.