• Journal of the Institute of Electronics Engineers of Korea SC
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• v.41 no.2
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• pp.37-44
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• 2004

In this paper, we performed the design and the development of the wide-band correlation board to be an important role in the autocorrelation spectrometer's building for the observation study of an extra-galaxy's spectral lines and the survey research of the special radio sources in field of the radio astronomy. In this research, the developed correlation board by using QUAINT correlator chip(made by NRAO) has maximum 100 MHz clock speed and operate at a intermediate frequency with 400 MHz bandwidth. For the Performance test we supply the 0.5 and 1.67 MHz rectangular wave, then we obtain the autocorrelation coefficients. The final results, which process by using FFT, get the almost same results compare with the theoretical correlation.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.6 no.3
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• pp.95-100
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• 2007

In this paper, a twice folded TEM horn antenna for 70 kV impulse high power system is proposed. The length reduction of 50 % is achieved by folding a conventional TEM horn antenna twice. The array elements are fed by the stripline power divider using the Chebyshev transformer. The power divider feeds four TEM horn antenna elements with an in-phased uniform power, and it covers a wide bandwidth ($150\;MHz\;{\sim}\;768\;MHz$, VSWR<2.0). Considering the air breakdown at peak 70 kV impulse, the proposed antenna maintains the 25 mm gaps between conducting plates. The dimension of the twice folded horn antenna is $1730\;{\times}\;1600\;{\times}\;300$ (mm3), and the operating frequency is from 152 MHz to 750 MHz under 10 dB return loss. The peak gains are measured from 6.77 dBi to 10.70 dBi at $400\;MHz\;{\sim}\;750\;MHz$.

• Journal of the Korean Institute of Gas
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• v.10 no.2 s.31
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• pp.61-67
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• 2006

We developed the ultrasonic phased array technique for obtaining ultrasonic images of electrofusion joints of polyethylene piping. And we inspected 4 cases at fields with this technique. First case is for the 300 mm diameter polyethylene electrofusion joint by using 3.5 MHz phased array sensor, second is for the 350 mm diameter saddle electrofusion joint, third is for the 400 mm diameter electrofusion joints and the last one is for the 400 mm diameter piping joints which will be used at 300 kPa suppling pressure.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.175-175
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• 2012

플라즈마를 이용하는 공정은 평판 디스플레이와 박막 트렌지스터, LCD 같은 반도체 산업에 널리 사용되고 있다. 최근 이와 같은 산업을 위한 공정은 마이크로 단위 이하에서 진행되고 있으며, 그 크기가 작아질수록 공정을 위한 비용은 증가하게 되었다. 따라서 제품의 대량생산 및 원가절감을 위해 웨이퍼의 대구경화가 진행되었고, 그런 대구경의 웨이퍼을 생산하기 위한 대면적 플라즈마 소스 개발 역시도 필요하게 되었다. 그리고 2014년에는 450 mm 크기의 웨이퍼가 사용될 것으로 예상되고 있다. 450 mm 대구경 웨이퍼용 유도결합플라자마 장치를 이용하여 플라즈마의 특성을 Langmuir probe를 사용하여 측정하였다. 플라즈마를 방전시키는 안테나의 형태는 spiral 형태의 안테나를 사용하였고, 이중주파수를 사용하기 위해 spiral 형태의 안테나를 두개로 나누어 안쪽의 안테나에는 2 Mhz를 바깥쪽의 안테나에는 13.56 Mhz를 인가하였다. 공정 압력은 10 mTorr로 유지하고 안쪽의 2 Mhz 안테나에는 100~800 W까지 변화시키고 바깥쪽의 13.56 Mhz 안테나에는 100~1,000 W까지 변화시켜 그 때의 플라즈마의 특성을 분석해 보았다. Langmuir probe를 이용하여 방전된 플라즈마를 관찰한 결과, 기판 위에서의 플라즈마 균일도가 4~23%가 되는 것을 확인 할 수 있었다. 13.56 Mhz의 인가되는 파워를 고정 시키고 2 Mhz만을 변화시켰을 경우 2 Mhz의 파워를 400 W까지 증가시켰을 때는 플라즈마의 밀도가 서서히 증가하였으나 400 W 이상에서는 밀도가 크게 증가하는 것을 볼 수 있었다. 하지만 플라즈마의 온도와 potential의 경우 밀도와는 반대로 2 Mhz에 인가되는 파워가 증가 될수록 감소하는 경향을 보였다. 위의 실험을 통해 우리는 전자에너지분포함수(EEDFs)를 얻을 수 있었고, 그 안에서 낮은 주파수(2 Mhz)를 이용하여 낮은 에너지를 가진 전자의 밀도를 조절할 수 있다는 것과 높은 주파수(13.56 Mhz)에 인가된 파워가 증가함에 따라 높은 에너지를 얻을 수 있다는 결과를 확인 할 수 있었다.

• Proceedings of the IEEK Conference
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• 2002.06a
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• pp.163-166
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• 2002

Recently, two kinds of the digital satellite receiver for radio and television have been developed as the global receiving system. The frequency bands of the satellite radio system are ranging from 1, 400MHz to 2, 600MHz, while the satellite television system are ranging from 11, 000MHz to 13, 000MHz New anti-discern antennas have been developed so that satisfies the Omni-characteristics in the horizontal directivity and approximately 45$^{\circ}$'elevation angle in the vertical directivity. These results were similar to the discern antenna except the anti-vertical directivity.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.8
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• pp.741-747
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• 2002

In this paper, NRD guide band pass filter with newly designed inductive iris structure is proposed and analyzed with its test results. In case of common NRD guide filter with air gap coupled structure, it was not easy to fabricate and process or each NRD guide dielectric resonator blocks using PTFE. However, in this our research, each dielectric resonator fabricated in a single NRD guide is coupled with inductive iris located on metal plates. The structure is suitable for mass production of a precise and reliable millimeter-wave filter applications. As a result of measurements, designed NRD guide inductive iris filter has superior performance. The pass band is 38.66~39.06 MHz with 400 MHz bandwidth, insertion loss is about 1.4 dB and return loss is below -18 dB.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.4
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• pp.366-374
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• 2009

ITU has considered the 3,400$\sim$4,200 MHz band, which is allocated worldwide on a primary basis to the FSS, as a candidate band for future development of IMT system. In this band, this paper presents the results of the sharing studies performed between FSS and IMT systems through the theoretical and simulation analysis on the interference from multiple IMT base stations into a receiving FSS earth station considering the interference mitigation techniques such as antenna tilt angle and 3 sectors on the IMT base station. By using the long-term and short-term interference threshold, the coordination areas for the FSS earth station are provided to share frequency in 3,400$\sim$4,200 MHz band between FSS earth station and multiple IMT base stations in future.

• Journal of the Korea Convergence Society
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• v.8 no.9
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• pp.9-16
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• 2017

In this paper, sub-microwave oscillator sensor is proposed to non-invasively monitor the glucose concentration level of the human biological tissue by oscillation frequency variation. Inductive slot in the ground plane of the microstrip line is combined with the biological tissue, to realize the resonator as a part of the oscillator sensor. The phantom box mimicking the human tissue is introduced for simulation of the resonator which resonance frequency correspondingly shifts up on three step glucose concentration levels(0, 400, 800 mg/dL). Oscillator sensor circuit is fabricated as a prototype. Pig tissues instead of human is used. Oscillation frequency shift of about 14 MHz per glucose level of 400 mg/dL has been successfully measured around 1,100 MHz. This proves that the proposed sensor is applicable to a blood glucose sensor.

• Journal of Advanced Navigation Technology
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• v.19 no.2
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• pp.168-174
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• 2015

Wireless communication system for firefighters has an important role as the last communication method between the commander and the firefighters in disaster sites like fire. But the operation of Gyeongnam wireless communication system is installed, and maintained and controlled without criteria for the selection of a transmitting station and the analysis of propagation environment because of the lack of budget and the absence of professional personnel. To improve the performance of the radio station, this paper theoretically calculated free space loss of UHF 400 MHz band used by all firefighters in Gyeongnam and diffractions caused by single and multiple obstacles and computed the error after comparing the results of the actual measurement to those of simulation with FRAS operated by KFL. In the results, Deygout model was the most consistent with the actual measurement for 400MHz band in Kimhae site.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.4
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• pp.393-400
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• 2002

In this paper, a novel series feeding cross-aperture coupled microstrip antenna with the effect of hybrid feeding is proposed and demonstrated experimentally to improve narrow axial ratio bandwidth of cross-aperture coupled antenna with single feeding among the various methods for generating circular polarization. The validity of a proposed series feeding cross-aperture coupled microstrip antenna is shown by comparing experimental results between the reported and the proposed microstrip antenna, and 2${\times}$2 array microstrip antenna based on the proposed single microstrip antenna used sequential rotation technique to accomplish broader axial ratio bandwidth. In the proposed single and 2${\times}$2 array microstrip antenna, the measured axial ratio bandwidths are 110 ㎒(4.6%) and 420 ㎒(17.5%), maximum gains are 8.2 ㏈i and 12.5 ㏈i, 3 dB gain bandwidths are above 400 ㎒(16.7%), and impedance bandwidths for the VSWR<1.5 are 240 ㎒(10%) and 500 ㎒(20.8%), respectively.