• 방송공학회논문지
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• 제16권1호
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• pp.144-154
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• 2011

본 논문에서는 고속, 저전력 비디오 부호화에 적합한 변환영역 Wyner-Ziv 분산비디오부호화기를 더욱 고속화하기 위한 병렬처리 방법을 제안한다. 기존의 변환영역 Wyner-Ziv 분산비디오부호화 방법은 양자화 된 변환계수를 비트플레인 단위로 분해한 후 비트플레인별로 순차적으로 LDPCA 채널코드로 부호화함에 따라 전체 부호화 연산량에서 LDPCA 부호화가 평균적으로 60% 정도 차지하였고, 이러한 복잡도는 고비트율로 부호화 할수록 더욱 증가하였다. 본 논문에서는 이런 분산비디오부호화 방법의 복잡도 문제를 개선하기 위해 여러 개의 비트플레인들을 하나의 메시지묶음으로 묶어서 한 번의 연산으로 여러 개의 데이터를 동시에 고속 LDPCA 채널코드 부호화하는 병렬화 방법을 제안한다. 이를 통해 기존의 순차적 방법에 비해 저비트율에서는 8배, 고비트율에서는 55배까지 LDPCA 채널코드 부호화 속도를 향상시켰다. 결과적으로 전체 변환영역 Wyner-Ziv 분산비디오부호화에서 LDPCA 채널코드 부호화의 상대적인 복잡도 비율을 평균 9%까지 낮출 수 있었으며, Wyner-Ziv 영상의 부호화 속도도 QCIF 크기 영상을 2.5GHz 속도의 CPU를 가진 PC환경에서 GOP 길이가 64인 경우 초당 700 ~ 2,300장을 부호화 할 수 있음을 확인했다. 제안 방법은 LDPCA를 사용하는 화소영역 Wyner-Ziv 분산비디오부호화에도 적용 가능하여 고속의 부호화가 요구되는 다양한 응용에 활용이 기대된다.

• 한국산학기술학회논문지
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• 제11권1호
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• pp.125-129
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• 2010

본 논문에서는 절전센서용 10GHz 대역 마이크로스트립 구형패치 배열 안테나의 설계 방법을 제안 하였다. 안테나는 송신안테나 $1{\times}2$배열, 수신안테나 $1{\times}2$배열로 각각 구성 하였다. 안테나는 CST MWS를 사용하여 시뮬레이션 하였고 FR-4 기판(h=1.0mm, ${\varepsilon}r=4.4$)을 사용하여 제작하였다. 시뮬레이션에서 대역폭은 4%(VSWR$\leq$2), 이득은 6.3dBi, 빔폭은 약 60o(El)/15o(Az)로 예측되었다. 시뮬레이션 결과를 이용하여 안테나가 제작되었고 안테나는 절전센서용 RF 송수신기 회로 뒷면에 설치되어 측정 되었다. 측정된 안테나의 대역폭은 7%(VSWR$\leq$2), 이득은 4.8dBi, 빔폭은 약 55o(El)/15o(Az)로 예상과 유사한 결과를 얻었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.265-265
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• 2007

In the present work, we have studied low temperature sintering and microwave dielectric properties of $ZnAl_2O_4$-zinc borosilicate (ZBS, 65ZnO-$25B_2O_3-10SiO_2$) glass composites. The focus of this paper was on the improvement of sinterability, low dielectric constant, and on the theoretical proof regarding of microwave dielectric properties in $ZnAl_2O_4$-ZBS glass composites, respectively. The $ZnAl_2O_4$ with 60 vo1% ZBS glass ensured successful sintering below $900^{\circ}C$. It is considered that the non-reactive liquid phase sintering (NPLS) occurred. In addition, $ZnAl_2O_4$ was observed in the $ZnAl_2O_4$-(x)ZBS composites, indicating that there were no reactions between $ZnAl_2O_4$ and ZBS glass. $ZnB_2O_4\;and\;Zn_2SiO_4$ with the willemite structure as the secondary phase was observed in the all $ZnAl_2O_4$-(x)ZBScomposites. In terms of dielectric properties, the application of the $ZnAl_2O_4$-(x)ZBS composites sintered at $900^{\circ}C$ to LTCC substrate were shown to be appropriate; $ZnAl_2O_4$-60ZBS (${\varepsilon}_r$= 6.7, $Q{\times}f$ value= 13,000 GHz, ${\tau}_f$= -30 ppm/$^{\circ}C$). Also, in this work was possible theoretical proof regarding of microwave dielectric properties in $ZnAl_2O_4$-(x)ZBS composites.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1680-1683
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• 2003

To describe the performance of an antenna, some parameters are necessary. Some of the parameters are interrelate and not all of them must be specified for complete description of antenna performance. The parameters in characteristics of printed antenna for this analysis are radiation pattern, input impedance, VSWR, S parameter and electromagnetic field. In this paper we will consider two shaped of slot antennas one is triangular slot antenna and other is L - shape slot antenna for compare the radiation pattern, return loss, and VSWR. Two slot antennas are designed to have a resonant frequency at 10 GHz. The microstrip line is designed to be 50 ohms in order to match the measurement system, it has the substrate of the thickness = 1.52 mm and dielectric constant (${\varepsilon}_r$) 2.17. The problem space in the FDTD analysis are $60{\times}123{\times}100$ cells for L-shape slot antenna and $50{\times}171{\times}120$ cells for triangular slot antenna with the cell dimensions ${\Delta}x=0.152\;mm.$, ${\Delta}y={\Delta}z=0.15\;mm.$

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2005년도 추계종합학술대회
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• pp.623-626
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• 2005

In this paper, we proposed a new type SIR bandpass filter using DAML. This filter is consisted of 2 layers with MEMS resonator layer and CPW feed line. DAML ring resonator is elevated with $10\;{\mu}m$ height from GaAs substrate. Using MEMS processing, we are able to realize SIR bandpass filter easily. Furthermore it is useful to integrate on conventional MMICs because it has CPW interfaces and ring resonator is isolated from substrate by air-gap. We optimized and measured the results that $S_{21}$ attenuation at rejected band is over 15 dB, insertion loss is inside the limit of 3 dB, and relative bandwidth is about 10 % at 60 GHz

• 대한전자공학회논문지TC
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• 제45권11호
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• pp.55-60
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• 2008

본 논문에서는 CRLH(Composite Righ/Left Handed) 전송선과 PIN 다이오드를 이용한 이중대역 RF 스위치를 제안하였다. 일반적인 RF 스위치가 RH(Right Handed) 전송선 및 PIN 다이오드로 구성되는 것과는 달리, 제안된 RF 스위치는 CRLH 전송선을 이용함으로써 이중대역 특성을 만족하였다. 설계된 CRLH전송선은 Open-Stub를 이용하여 PIN 다이오드 패키지 인덕턴스로 인한 격리도 감소를 해결하였다. RF 스위치는 GSM 주파수 대역인 900MHz와 DCS 주파수 대역인 1.8GHz의 이중 대역에서 설계 및 제작하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제33권1호
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• pp.159-165
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• 2009

In this study, using a periodical ground structure(PGS) on GaAs monolithic microwave integrated circuit(MMIC), transmission line with a high isolation characteristic was developed for application to compact signal/bias lines of highly integrated MMIC. And the origin of the high isolation characteristic was theoretically investigated. The high isolation characteristic was originated from a resonance between adjacent microstrip lines employing PGS. With only a spacing of $20{\mu}m$, the coupled microstrip line employing PGS showed an isolation value of -47 dB at 60 GHz. The frequency range for high isolation was easily controlled by changing the PGS structure. Above results indicate that microstrip lines employing PGS are very useful for application to compact signal/bias lines of highly integrated MMIC requiring a high isolation characteristics between lines. In addition, equivalent circuit employing closed-form equation for the coupled line with PGS was also extracted.

• 천문학회보
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• 제38권2호
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• pp.35.1-35.1
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• 2013

By probing nuclear regions and overall properties of AGN hosts as a function of their environments, we aim to observationally examine how AGN activities are related to their surroundings. We have selected eight representative AGN hosts in the Virgo cluster, including seven cluster members (M49, M60, M84, M87, NGC 4435, NGC 4526, NGC 4636) and one galaxy that is likely to be background (NGC 4261) but still close enough to be studied in high resolution. The selected galaxies are located in a range of density regions showing various morphology in 1.4 GHz continuum. High resolution observations with the KVN allow us to access the inner region of the AGN without suffering from dust extinction and synchrotron self-absorption. Since half of our targets are weak to be detected at K-band within its coherence time, we applied phase referencing (fast antenna position switching) to calibrate fast atmospheric phase fluctuations. We successfully detected relatively bright AGNs, such as M87, M84 and NGC4261, but no detection signature was found to the other members of the sample. In this talk, we will present our first results from our KVN observations, while we will discuss in detail the applied technique and our immediate future plans.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2005년도 종합학술발표회 논문집 Vol.15 No.1
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• pp.125-130
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• 2005

This paper suggests an efficient method of protection ratio calculation and shows some calculated results applicable to frequency coordination in microwave relay system networks, and the net filter discrimination (NFD) associated with Tx spectrum mask and overall Rx filter characteristics has been examined to obtain the adjacent channel protection ratio. The protection ratio comprises several factors such as C/N of modulation scheme, noise-to-interference ratio, multiple interference allowance, fade margins of multi-path and rain attenuation, and NFD. According to computed results for 6.7 GHz, 64-QAM, and 60 km at BER $10^{-6}$, fade margin and co-channel protection ratio are 41.1 and 75.2 dB, respectively, In addition, NFD for channel bandwidth of 40 MHz reveals 28.9 dB at the first adjacent channel, which results in adjacent channel protection ratio of 46.3 dB. The proposed method provides some merits of an easy calculation, systematic extension, and applying the same concept to frequency coordination in millimeter wave relay system networks.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 춘계학술대회 논문집 전자세라믹스 센서 및 박막재료 반도체재료 일렉트렛트 및 응용기술
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• pp.60-63
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• 2000

The $0.94MgTiO_3-0.06SrTiO_3$ ceramics were prepared by the conventional mixed oxide method. The structural properties were investigated with sintering temperature and composition ratio by XRD, SEM and DT-TGA. According to the X-ray diffraction patterns of the $0.94MgTiO_3-0.06SrTiO_3$ ceramics, the cubic $SrTiO_3$ and hexagonal $MgTiO_3$ structures were coexisted. Increasing the sintering temperature from $1325^{\circ}C$ to $1400^{\circ}C$, average grain size was increased from $5.026{\mu}m$ to $8.377{\mu}m$. In the case of the $0.94MgTiO_3-0.06SrTiO_3$ ceramics sintered at $1325^{\circ}C$, dielectric constant, quality factor and temperature coefficient of resonant frequency were 21.66, 2,522(at 7.34GHz), $+71ppm/^{\circ}C$, respectively.