• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.1
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• pp.23-30
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• 2010

In this paper, a design for the 900MHz bandwidth RFID reader antenna with circular polarization is proposed and experimentally investigated. The 900MHz bandwidth RFID reader antenna is proposed as a simple radiator with loading capacitor to generate LHCP(Left Hand Circular Polarization). Also, the design and fabrication of antenna has the returnloss of -32.28dB at the center frequency of 1010MHz and Bandwidth of 12.5% at 905Hz~1030MHz. Proposed LHCP antenna of maximum gain is 6dBi and satisfy axial ratio based on 2. From the measured result, axial ratios based on 2 are observed at the operating frequencies. The proposed antenna is suitable for RFID applications in wireless communications.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.4
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• pp.499-505
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• 1998

This paper presents the method for an estimation of discharge current waveshapes in short gap discharge by a radiated electromagnetic field. The method of currentwaveform estimation described is using the one antenna method(single field method) with a measured electric or magnetic fields at given field point by a time domain antenna. In order to verify the availability of the estimated theory, the discharge current waveshape estimation was performed by one antenna method using the measured electric fields of Wilson & Ma and compared with experiments.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.2
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• pp.47.1-47.1
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• 2010

태양전파폭발위치관측기(KSRBL)는 단일 안테나 전파분광기로써 미 뉴저지공과대학과의 협력으로 2009년 8월에 한국천문연구원에 개발 설치되었다. 1 MHz 스펙트럼 분해능과 1초의 시간 분해능을 가지고 있고 관측할 수 있는 주파수 대역은 245, 410 MHz 와 0.5-18 GHz에 이르는 광대역이다. 또한 태양 전면 $0.03^{\circ}$ 각거리 안의 오차 범위 내에 태양 폭발 위치를 감지할 수 있다. 전파 관측은 LabVIEW와 IDL 프로그램에 의해 미리 짜여진 관측 스케줄에 따라 매일 자동으로 진행된다. KSRBL 설치 이후 현재까지의 데이터에 대한 관측 통계를 분석 하였다. 관측된 전파폭발의 수를 다른 사이트와 비교하고, 정상 관측 되는 날의 빈도, 기기 오류 발생 빈도, 데이터 안정도 및 손실률 등의 변화양상을 추적하였다.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.1
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• pp.53.1-53.1
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• 2014

본 연구에서는 고궤도 및 원거리 우주물체의 추적 및 관측이 용이한 광학관측 시스템을 이용하여 정지궤도위성을 관측하였고, 광도곡선 분석을 통해 식별정보를 획득하였다. 정지궤도 위성은 자세에어 방법에 따라 회전 안정화 위성과 3축 안정화 위성으로 나뉘며, 3축 안정화 위성은 다시 통신위성과 지구관측 위성 등으로 나뉜다. 회전 안정화 위성의 식별 연구를 위해 중국의 FY-2 위성을 관측대상으로 선정하였고, 3축 안정화 위성의 식별을 위해 한국의 COMS-1 위성을 관측 대상으로 선정하였다. 회전안정화 위성은 Sidereal Tracking Mode로 관측하면 위성의 궤적이 선 모양으로 나타난다. 이때 나타난 궤적의 pixel value 값을 확인하면 일정한 주기로 밝기가 변화 하는 것을 확인할 수 있으며, FFT를 수행하면 위성의 회전율과 회전 주기를 구할 수 있다. 3축 안정화 위성은 Stare Mode로 관측하여 측광하면 광도곡선을 획득할 수 있다. 위성의 형상을 결정하는 본체, 안테나, 태양전지판을 모델링하여 광도곡선 시뮬레이션결과와 비교하면 각각의 형상이 광도곡선에 미치는 영향과 특징을 알 수 있고, 이를 통해 식별정보를 획득할 수 있다. 이상의 분석을 통해 얻은 FY-2위성과 COMS-1 위성의 식별정보를 제시하고 향후 우주물체 식별 연구에 활용하고자 한다.

• Bulletin of the Korean Space Science Society
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• 2010.04a
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• pp.37.2-37.2
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• 2010

GPS 관측자료를 이용하여 최근 발생한 칠레지진에 의한 지각의 변위를 결정하고 결과를 분석하였다. 고정밀 측지용 이중주파수 GPS 수신기 및 안테나가 장착된 관측소의 자료를 처리하면 수mm 정밀도로 관측소의 위치를 결정할 수 있으며, 수년간의 관측자료가 누적되면 연간 mm급의 움직임도 관측할 수 있어 판운동이나 지진, 단층연구 등에 널리 활용되고 있다. 이번 2010년 2월 27일 칠레 중서부에서 발생한 지진은 인근 지역을 30 cm 이상 움직였을 것으로 예상되며 8.8의 대형 지진규모와 많은 인명 및 재산피해를 유발시켜 학계뿐만 아니라 일반 언론에도 많은 주목을 받고 있다. 이 연구에서는 지진이 발생한 지역 부근에 위치한 국제 GPS 기준망의 GPS 관측자료를 처리하여 지진 발생 전후의 변위를 산출하고 분석하였다. 자료처리를 위해 Bernese GPS S/W 5.0을 사용하였고 24시간단위 자료에 대해 이중차분방법과 단독정밀측위방법을 사용하였다. 또한 지진이 발생 도중의 변위를 관찰하기 위해 이동측위방법을 사용하여 30초마다의 움직임을 계산하였다.

• Journal of Navigation and Port Research
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• v.32 no.5
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• pp.363-368
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• 2008

This paper presents a miniaturization design technique of radio frequency identification (RFID) tag antenna operated in 910 MHz band. Miniaturization structure design for a tag antenna is performed by structure application of the folded dipole and meander line. In order to realize the maximum power transmission, imaginary part of a chip impedance and a tag antenna impedance is matched by complex conjugate number. The optimized tag antenna size is $50\;nm\;{\times}\;40\;nm\;{\times}\;1.6\;nm$ and its size is reduced about 62 % comparison with antenna size of reference [4]. The measured results of fabricated tag antenna are confirmed the reasonable agreement with prediction. The read range of the tag antenna with chip observed about 5 m.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.3 s.118
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• pp.273-281
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• 2007

This paper presented design for a dipole antenna operated at 900 MHz band RFID tag, and antenna performance varied by the sticked material was experimentally evaluated. When dipole antenna was sticked by the material having a difffrent electric characteristic such as dielectric material, fero-magnetic material and conductor, variations of antenna return loss and radiation pattern according to the sticked material kinds, size, and height between antenna and the sticked plate were experimentally observed and evaluated. When antenna was sticked by dielectric surface, the measured return loss and radiation pattern by affection of different dielectric permittivity ratio showed resonant frequency shift of about 40 MHz and relative attenuation of 1 dB to 3 dB. Even though frequency shift by size variation of the sticked plate was observed, the measured radiation pattern of dipole antenna located on the sticked plate was similar with one without backside plate. In the case of conductor or fero-magnetic material as the sticked ground plate, because of frequency shift and phase difference by distance between dipole antenna and the sticked ground plate, amplitude decrease of radiation pattern at 910 MHz was observed about 5 dB above.

• Aerospace Engineering and Technology
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• v.1 no.1
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• pp.135-140
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• 2002

The position and trajectory of in-flight rocket are important informations to determine the flight safety of rocket. In general tracking system, radar and transponder are used to acquire position information. Rocket position and trajectory can be determined by using RF communication between ground station and in-flight rocket and antenna position data. Onboard transponder system is composed of RF receiving part, RF transmitting one, decoder and single TX/ RX antenna. Therefore circulator is necessary for minimizing RF signal interference. In this paper, the radar transponder system was developed to track the trajectory and position of KSR-Ⅲ by using radar.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.21 no.6
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• pp.241-249
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• 2022

This paper discusses the design of a ground clutter prevention fence for a radar wind profiler (RWP). The design point of the clutter fence is to improve the quality of the received signal by removing the non-weather clutter coming from the side. In this paper, a clutter prevention fence composed of a metallash mesh around the RWP is proposed, and the phase center of the antenna, the length, and height of the down fence, and the height and slop of the top fence through M&S are designed. The designed ground clutter prevention fence and 256 active phase array antennas were used as basic data. The effectiveness of the design was confirmed by a simulation. The side lobe in the ±90° direction was reduced by more than 30dB depending on the presence or absence of the designed ground clutter prevention fence. The fence was manufactured by 3D modeling, and the clutter shielding performance of approximately 20dB or more on the side of the antenna (±90°) was confirmed by applying it to the currently operated RWP.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.33 no.4
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• pp.231-244
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• 2015

The accuracy of reference point of VLBI antenna is mandatory to perform collocation of different space geodetic techniques. In this study, we evaluated the optimal methods for the 3D circle fitting to enhance the accuracy of the reference point of VLBI antenna. Two kinds of methodologies for the orthonormal coordinate system with translation of planar observation point and the unitary coordinate transforamation were suggested and their fitting accuracies were evaluated where the orthogonal distance was calculated by residual between observation point and fitting model and the recursive calculation was performed to improve the accuracy of 3D circle fitting. Finally, we found that the methodology for the unitary coordinate transformation is highly appropriate to determine the optimal equation for azimuth-axis and elevation-axis of VLBI antenna. Therefore, the reference point of VLBI antenna with high accuracy can be determined by the intersection of the above two axises (azimuth-axis and elevation-axis). This result is expected to be utilized for a variety of researches for connection between VLBI observation results and the national control point.