• Journal of information and communication convergence engineering
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• 제19권3호
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• pp.131-135
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• 2021

The interference between closely placed co-coverage satellites was analyzed. In general, a satellite network may use different orthogonal polarizations and frequencies to increase the throughput of a satellite. However, when orthogonal linear polarization (horizontal polarization and vertical polarization) or orthogonal circular polarization (left-handed circular polarization and right-handed circular polarization) is used, the signal from one polarization sense to another may be coupled, resulting in cross-polarization interference. This signal-coupling arises due to the finite value of the cross-polarization discrimination of the earth station. In this study, field equations were used to analyze the interference between adjacent satellites using co-frequency. The level of interference was compared to that when two adjacent satellites used the same polarization. The simulation results show that the interference mainly depends on the off-axis co-polar pattern and the cross-polar pattern of the earth station antenna.

• 한국전자파학회논문지
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• 제13권3호
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• pp.225-236
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• 2002

본 논문에서는 동일채널 이중편파를 적용하는 디지털무선중계장치의 직교편파간섭을 제거할 목적으로 직교편파간섭제거기(XPIC)의 이론적 모델링, 디지털 설계를 분석하였다. 또한 유한임펄스응답 여파기를 이용한 복소 시간영역 적응등화기(ATDE)를 설계하고, 이를 이용한 XPIC의 구조 및 제어방법을 ATDE와의 연동하여 제시하였다. XPIC와 ATDE를 연동으로 약 25㏈ 이상의 시그너쳐(signature)와 약 23㏈ 이상의 XPIC 개선인자를 얻을 수 있음을 모의실험으로 보였다. 설계된 직편파간섭제거기의 동작검증을 위해 동일채널 이중편파용의 64-QAM모뎀과 연동하여 탭의 수, 알고리즘의 수렴, 장치의 성능, 직교편파간섭제거기의 개선인자에 대한 결과도 검토하였다.

• 한국세라믹학회지
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• 제37권6호
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• pp.612-616
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• 2000

The effect of Co dopant on the (La, Sr)MnO3 cathode was investigated. La2Zr2O7 and SrZrO3 were formed as the reaction products between YSZ and LSMC. The reactivity of LSMC with YSZ increased with increasing Co content. However, the cathodic polarization resistance decreased with increasing Co doping. Therefore, doping Co at Mn site in the (La, Sr)MnO3 cathode was effective on controlling the polarization resistance of the cathode. The polarization property of LSMC-YSZ composite(60 wt%: 40 wt%) cathode was better than that of LSMC single cathode.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2001년도 종합학술발표회 논문집 Vol.11 No.1
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• pp.25-28
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• 2001

In this paper. to eliminate a cross-polarization interference caused by co-channel dual polarization technique of digital radio relay system(DRRS), a cross-polarization interference canceller(XPIC) is analysed in terms of the analytical modeling, digital design, and its performance. By virtue of a 13-tap adaptive equalizer and XPIC, about 23dB in XPIC improvement can be obtained by computer simulation. To show the operation of designed XPIC, some simulated results are reviewed under 64-QAM DRRS with co -channel dual Polarization.

• Corrosion Science and Technology
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• 제17권5호
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• pp.249-256
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• 2018

Metallic structures in the oil and gas production undergo severe degradation due to sweet and sour corrosion caused by the presence of $CO_2$ and $H_2S$ in the fluid environment. The corrosion behavior of 304 austenitic stainless was investigated in the presence of varying concentrations of $CO_2$ or $H_2S$ and $CO_2+H_2S$ to understand the effect of the parameters either individually or in combination. Potentiodynamic polarization study revealed that a small amount of $CO_2$ aided in the formation of calcareous deposit of protective layer on passive film of 304 steel, while increase in $CO_2$ concentration ruptured the layer resulting in sweet corrosion. The presence of $S^{2-}$ damaged the passive and protective layer of the steel and higher levels increased the degradation rate. Electrochemical impedance studies revealed lower polarization resistance and impedance at higher concentration of $CO_2$ or $H_2S$, supporting the outcomes of polarization study. XRD analysis revealed different types of iron carbides and iron sulphides corresponding to sweet and sour corrosion as the corrosion products, respectively. SEM analysis revealed the presence of uniform, localized and sulphide cracking in sour corrosion and general corrosion with protective carbide layer amid for sweet corrosion.

• 한국인터넷방송통신학회논문지
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• 제17권5호
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• pp.187-192
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• 2017

마이크로스트립 콤 어레이 안테나에 대한 CSRR-메타물질의 영향을 연구하였다. 마이크로스트립 콤 어레이 안테나는 12개의 방사체로 구성되었고 24GHz ISM 대역에서 16.09dBi의 이득과 0.24GHz 대역폭을 갖도록 설계하였다. 설계된 안테나는 안테나 면에 수직한 방사빔과 16.09dBi의 동일편파 이득, -10.86dBi의 교차편파 이득을 갖고 있었다. CSRR-메타물질은 0.24GHz이던 마이크로스트립 콤 어레이 안테나의 임피던스 대역폭을 3.6GHz로 대폭 증가시켰으나 동일편파 이득이 10.8dBi로 되고 교차편파 이득이 14.1dBi로 되어 동일편파와 교차편파가 혼재했으며 안테나 이득을 1.99dB 만큼 저하시켰다. 한편, CSRR 링의 스플릿 방향에 따른 연구에서 링의 스플릿 방향을 위로하거나 아래로 했을 때는 거의 같은 특성을 보였다. 그러나 링의 스플릿 방향을 위와 아래로 교번하여 배치하였을 때는 동일편파 이득이 -1.29dBi로 감소하고 교차편파 이득이 13.9dBi로 증가하여 교차편파가 주가 되는 파로 변환되었다.

• 동력기계공학회지
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• 제18권6호
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• pp.40-44
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• 2014

The purpose of this paper is to investigate polarization characteristics of WC-based alloy coatings in alkaline solution. The coatings were fabricated with WC-CrC-Ni, WC-Co-Cr and WC-Co composite powders by HVOF process. Corrosion tests of coatings and substrate were carried out using potentiostat/galvanostat at solution with pH 8 and pH 13. Corrosion potential(Ecorr) and corrosion current density(Icorr) could be studied from polarization curve, and corrosion behavior was analyzed by SEM and EDS. WC-Co-Cr coating and WC-CrC-Ni coating showed more favorable anti-corrosion characteristics than WC-Co coating and substrate at solution with pH 8 and pH 13.

• Journal of Multimedia Information System
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• 제7권4호
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• pp.239-248
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• 2020

The performance of the facial recognition system is determined by many technical factors. Further, most of the technical factors have been realized or are still in continued research. The recognition rate has a great influence on performance not only by technical factors but also by other factors. However, researchers are trying to improve the recognition rate by focusing only on technical factors. The mechanism of recognizing is to compare a face image obtained by photography to an already stored face image and determine the score of the similarity. However, if the photographed image is damaged by external light, even a system with a good algorithm will fail to recognize it. Therefore, it is important to prevent the disturbance of light entering from the outside, so it should be blocked, but the camera will not work without light. Thus, it is proposed that a method to secure the external light but block the disturbance of light that affects photography. A method of blocking disturbance light is to use a polarization filter. There are three polarization methods: circular polarization, linear polarization, and elliptical polarization. In this paper, an experiment was performed to overcome disturbance of light using only a circularly polarized filter. In addition, a lighting system that reproduces disturbance light was provided for the experiment, and light of varying intensities and angles was installed to affect the face recognition camera. As a result of actual application, it was determined that a very improved recognition performance in various disturbance light environments.

• 전기화학회지
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• 제4권3호
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• pp.125-131
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• 2001

용융탄산염 연료전지의 장기 운전시 각 전극별 분극의 변화를 Au, $CO_2/O_2$ 기준전극이 부착된 단위전지를 이용하여 성공적으로 해석하였다. 서로 다른 구성요소로 조합된 네 가지 단위 전지를 운전하며 각 전극의 분극을 해석한 결과, 이미 알려진 바와 같이 공기극의 분극 크기가 연료극의 경우보다 큰 것을 실험적으로 측정할 수 있었다. 고온 부식 방지를 위해 cell frame의 wet seal부분에 Al코팅을 한 전지는 6,000시간까지 성능을 유지하여 부식이 전지 성능 저하에 큰 역할을 하고 있음을 알 수 있었다. 한편, $LiCoO_2$가 코팅된 안정화 공기극은 일반적으로 사용되는 NiO 공기극보다 lithiation에 필요한 시간이 길어 운전 초기에 공기극 분극이 크고 성능이 낮았으나 지속적인 운전으로 공기극이 충분히 lithiation되면서 공기극의 분극이 작아지고 성능도 점차 증가하였다. $Li_2CO_3/Na_2CO_3$ 전해질을 사용한 전지는 운전 중 성능이 하락과 상승을 반복하는 진동현상을 보였는데 이는 연료극보다는 공기극의 영향으로 해석되었다. 대부분의 단위전지들이 급격한 성능 하락을 보였을 경우의 공기극 분극은 급격히 증가하였으며 이로써 용융탄산염 연료전지의 수명 향상을 위해서는 공기극의 개선이 필수적이라는 것을 알 수 있었다.

• 동력기계공학회지
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• 제18권4호
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• pp.72-77
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• 2014

The aim of this study to investigate polarization characteristics of WC-based alloy coatings fabricated by high velocity oxygen fuel(HVOF) process. The coatings were fabricated by HVOF process with WC-CrC-Ni, WC-Co-Cr, WC-Co composite powders. Corrosion tests were carried out using potentiostat/galvanostat at solution with pH 2 and pH 6. Corrosion potential(Ecorr) and corrosion current density(Icorr) could be analyzed from polarization curve. WC-Co-Cr coating showed more incorrodible characteristics than other coatings at solution pH 2. WC-CrC-Ni coating was more favorable anti-corrosion characteristics than other coatings at solution with pH 6.