• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• 제26권10호
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• pp.27-34
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• 2012

If obstacle in GIS(Gas Insulted Switchgear), its affects are great are on the community and it is consequently demanded lots of difficulities to recover and repair. Accordingly, diagnosis techniques, that are able to prevent from accidents before they happen by providing more stable and highly reliable power effectively and finding sign of the accidents is very important. A novel UHF(Ultra High Frequency)-microstrip antenna is presented. The measured impedance bandwidth of the proposed antenna is from 0.5GHz to 15GHz with the stop band from 0.5GHz to 10.7GHz for VSWR<2. Form results of this study, The antenna is will play an important role for the senser for insulation diagnosis system by UHF method of real site GIS and power equipment using $SF_6$ gas.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• 제18권6호
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• pp.602-611
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• 2007

In this paper, the forward link of UHF RFID system is modeled in accordance with the EPCglobal class 1 generation 2(EPCglobal C1G2) UHF Radio-Frequency Identity protocol specification at $860{\sim}960MHz$. Based on the constructed model, characteristics on the forward link signal for the EPCglobal C1G2 RFID reader are simulated with the help of a MATLAB softwarein order to extract the design parameters of a transmit digital filter which meets the Korean RFID regulations. Herein, the forward link model is consisted of PIE source coding, transmit digital filter, modulation, local oscillator, and antenna. From the simulation results, the ranges of three design parameters(roll-off factor, cutoff frequency, the number of tabs) for transmit digital filter are obtained with different modulation techniques and the Tari(type a reference interval) values. Finally, DSB/SSB-ASK modulation technique can not satisfy the EPCglobal C1G2 specification when Tari equals to $6.25{\mu}sec$ in a multiple-reader environment. Consequently this paper can provide a guideline for design parameters of a RFID reader as well as the basic scheme of analyzing frequency interference problems in RFID environments, including multiple-reader and dense-reader environments.

• Journal of the Korea Academia-Industrial cooperation Society
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• 제22권1호
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• pp.777-785
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• 2021

Many utility lines are buried underground to provide various functions of the city. Because historical records are not managed systematically, damage has occurred during excavation. In addition, the demand for an underground facility management system is increasing as the aerial underground project is progressing. By attaching an electronic recognition sensor to an underground facility, such as pipelines, the management history and site conditions can be carefully managed. Therefore, in this study, electronic recognition sensors, such as BLE Beacon, UHF RFID, geomagnetic sensor, and commercial marker, were tested to analyze the strengths, weaknesses, and field applicability through a pilot project. According to the limited research results collected through two pilot projects, the installation depth is most important to demonstrate the performance of the electronic reader. In addition, because it should be used in urban areas, the influence of environmental interference should be minimized, and there should be no performance degradation over time. In the case of the geomagnetic recognizer, the effect of environmental interference was large, and performance degradation occurred over time using the BLE Beacon. In the field situation, where the installation depth can be controlled to less than 40cm, the utility of the battery-free UHF RFID was the best.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• 제21권5호
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• pp.510-518
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• 2010

In this paper, the designed and implemented results of CFL linearization chip which can be used in mobile radio and TRS terminal of UHF band(380~910 MHz), using $0.6\;{\mu}m$ BiCMOS process based on Si, are shown. As gain control circuits for modifying transmit power are inserted not only in feedback path but also in forward path, the stability of CFL is maintained. And, DC-offset correction function of S/H structure, which is suitable for walkie-talkie PTT operation and is easily implemented, is realized. The performance test results of transmitter show that the regulation of FCC emission mask at PEP 3 W(34.8 dBm) is satisfied when the CQPSK modulated signal is fed and more than 30 dBc improvement of 3rd order IMD is achieved when two-tone signal is inputted.

• Journal of Navigation and Port Research
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• 제27권5호
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• pp.505-511
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• 2003

In this paper, a driving amplifier stage with 1 Watt output has been designed and fabricated, which is operating at UHF band( 470 ∼ 806 MHz) for digital TV repeater. In the driving amplifier stage, preamplifier and 1 Watt unit amplifier are integrated by one electric substrate which is 2.53 in dielectric constant and 0.8 mm thickness. When the driving amplifier stage is flown by bias voltage of 28 V DC and current of 900 mA. it has the gain of more than 53.5 dB. the gain flatness of $\pm$0.5 dB and return loss of less than -15 dB in 470 ∼ 806 MHz. Also, when two signals at 2 MHz frequency interval are input port into the driving amplifier stage with 1 Watt output, it resulted in excellent characteristics to designed specification with showing intermodulation distortion characteristics of more than 48 dBc.

• The Journal of Korean Institute of Communications and Information Sciences
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• 제34권12B호
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• pp.1468-1474
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• 2009

This paper shows an UHF RFID metallic tags using a Cavity structure for a long reading range. The reading range of a general passive tag is limited because the EIRP of a reader system is limited as 36㏈m by ISO 18000-6. To extend the reading range, the tag antenna should have a high gain antenna structure. The designed tag antenna is recognized over 10m range with a Cavity structure. The directivity pattern and the performance of the tag with the Cavity structure is stable when it is attached to a metallic object. The designed tag antenna has two kinds as cavity thickness. The sizes of designed tag antennas are $176\;{\times}\;52\;{\times}\;10\;mm$ and $176\;{\times}\;61\;{\times}\;30mm$ They can be attached to a large metallic materials and heavy equipments. The measured reading ranges of the tags are about 11m and 15m when they are attached to a metallic object.

• Journal of the Korea Academia-Industrial cooperation Society
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• 제13권5호
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• pp.2325-2331
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• 2012

Planar square-spiral antenna using a strip conductor is proposed and analyzed for RFID system in UHF band operating from 860MHz to 960MHz. By varying the length of common line, detached distance, strip line-space, strip line-width and the number of spiral turn, the optimized antenna are designed and fabricated in compact size without a matching-stub between the input port of the proposed antenna and RFID tag chip. From the optimized results, the frequency bandwidth in VSWR<2 has covered 100MHz in the RFID UHF band. The antenna gain has obtained 3.5dBi at the center frequency of 910MHz and the desired beam pattern has shown directional pattern on elevation and azimuth angle. Therefore, the proposed antenna is suitable for practical RFID applications requiring various tag chips with the specific input impedance.

• Journal of Biomedical Engineering Research
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• 제21권3호
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• pp.255-260
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• 2000

This paper presents a radio-telemetry patient monitor. which is used for intensive cal?e units. emergency and surgical operation rooms to monitor continuously patients' vital signs. The radio-telemetry patient monitor consists of a vital sign acquisition unit. wireless data transmission units and a vital sign-monitoring unit. The vital sign acquisition unit amplifies biological signals, performs analog signal to serial digital data conversion using the one chip micro-controller. The converted digital data is modulated FSK in UHF band using low output power and transmitted to a remote site in door. In comparison with analog modulation. FSK has major advantages to improve performance with respect to noise resistance with fower error and the potential ability to process and Improve quality of the received data. The vital sign-monitoring unit consists of the receiver to demodulate the modulated digital data, the LCD monitor to display vital signs continuously and the thermal head printer to record a signal.

• Journal of Advanced Navigation Technology
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• 제23권2호
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• pp.179-185
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• 2019

In this paper, we have studied narrow-band analog pre-distortion linearization technique using UHF 400 MHz band 20 W power amplifier. The analog pre-distorter used the SC1894 radio frequency power amplifier linearizer(RFPAL) provided by MAXIM Corp and through the look-up table technique confirmed the intermodulation distortion(IMD) performance and the adjusted channel leakage ratio(ACLR) improvement for bandwidth below 1 MHz which does not operate on existing chips. In the 400 MHz (400 ~ 500 MHz) band, IMD performance and the ACLR improvement of up to 17.46 dB based on 1-channel offset and up to 16.6 dB based on 2-channel offset were confirmed. In the system requiring the same linearity, we confirmed power efficiency improvement of 12.41% at output power of over 40 W.

• Journal of Astronomy and Space Sciences
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• 제29권1호
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• pp.33-40
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• 2012

Triplet Ionospheric Observatory (TRIO) CubeSatforIon, Neutral, Electron MAgneticfields (CINEMA) is a CubeSat with the weight 3 kg that will be operated in the orbit conditions of about 800 km altitude and $90^{\circ}$ inclination angle, using the S-band and ultra-high frequency (UHF)-band communication frequencies. Regarding the communication antenna loaded on the satellite, the two patch antennas has the downlink function in the S-band, whereas the two whip antennas has the function to receive the command sent by the ground station to the satellite in the UHF-band. The uplink ground station that communicates through the UHF-band with the CINEMA satellite was established at Kyung Hee University. The system is mainly composed of a terminal node controller, a transceiver, and a helical antenna. The gain of the helical antenna established at the Kyung Hee University ground station was 9.8 dBi. The output of the transceiver was set to be 5 W (6.9 dB) for the communication test. Through the far-field test of the established system, it was verified that the Roman characters, figures and symbols were converted into packets and transmitted to the satellite receiver in the communication speed of 9,600 bps.