• 한국통신학회논문지
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• 제33권12A호
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• pp.1233-1241
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• 2008

본 논문에서는 UMPC급의 휴대 단말에 장착 가능한 소형 MIMO 안테나를 설계 및 측정 분석하였다. 제안된 MIMO 안테나는 두 개의 노치 안테나와 하나의 변형된 모노폴 안테나를 이용해서 $40mm\;{\times}\;100mm$ 기판안에 세개의 방사 소자를 넣은 것이다. 각 안테나는 중심 주파수 1.8GHz에서 80-200MHz의 대역폭을 가진다. 또 전 주파수 대역에서 격리도가 l0dB 보다 크게 나타나고 있다. 제안된 MIMO 안테나의 성능 평가를 위해서 ARC/TARC, correlation, MEG를 소개하고 안테나의 성능을 평가 하였다. 포락선 상관도는 0.04이하로 계산되었고 평균 유효 이득(MEG)은 1에 가깝게 나타났다.

• Animal Systematics, Evolution and Diversity
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• 제27권3호
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• pp.262-267
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• 2011

Three species of the family Processidae, Hayashidonus japonicus (De Haan, 1844), Processa sulcata Hayashi, 1975 and Processa zostericola Hayashi, 1975 described with illustrations from Korea. Two of these species, H. japonicus and P. zostericola, represent new records for the Korean carcinological fauna. The genus Hayashidonus included the single species, H. japonicus is distinguished from other genera of Processidae by the broadly triangular rostrum, the obscure or absent dorsolateral spines of the telson, and the exceptionally long molar process of the mandible. Two species of the genus Processa, P. zostericola and P. sulcata are distinguishable each other by presence or absence of an obtuse process of the basicerite of antenna on the anteroventral margin. The basicerite of antenna arms with the obtuse process in P. zostericola, while in P. sulcata the basicerite of antenna lacks the process but is smooth on the ventral margin. A key to these species is presented.

• 한국인터넷방송통신학회논문지
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• 제11권2호
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• pp.29-34
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• 2011

본 논문에서는 각 홉에서 다중 안테나를 가지는 노드 간 채널 환경을 고려하여 가장 좋은 성능을 가지는 하나의 안테나와 하나의 중계기를 동시에 선택하는 시스템을 제안하며, 제안된 시스템의 성능을 분석한다. 다중 채널을 통해 다수의 수신 신호를 받아 MRC(Maximal Ratio Combining) 기법을 이용하여 다이버시티를 얻는 일반적인 시스템은 상대적으로 열악한 채널을 통과하는 신호 또한 수신하며, 이는 곧 시스템의 성능 저하로 이어지는 결과를 얻는다. 제안하는 시스템은 송신단-중계기, 중계기-수신단 간의 모든 채널 환경을 고려하여 가장 좋은 채널을 통해서만 데이터를 전송함으로써 열악한 채널을 통과하는 신호의 수신을 차단함으로써 성능을 향상시킨다. 따라서 가장 좋은 채널상의 안테나와 중계기를 동시에 선택하는 과정을 거치며, 이를 구현하기 위해 단일 중계기만을 선택하고 각 홉에서는 단일 안테나만을 이용할 수 있는 알고리즘을 제안한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제16권9호
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• pp.3152-3171
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• 2022

This work investigates the physical layer secrecy of a multi-antenna hybrid satellite-terrestrial relay networks (HSTRN) with jamming, in which a satellite aims to make communication with a destination user by means of a relay, along with spatially random eavesdroppers. In order to weaken the signals of eavesdroppers, the conventional relay can also generate intentional interference, besides forwarding the received signal. Shadowed-Rician fading is adopted in satellite link, while Rayleigh fading is adopted in terrestrial link, eavesdropper link and jamming link. The analytical and asymptotic formulas for the system secrecy outage probability (SOP) are characterized. Practical insights on the diversity order of the network are revealed according to the asymptotic behavior of SOP at high signal-to-noise ratio (SNR) regime. Then, analysis of the system throughput is examined to assess the secrecy performance. In the end, numerical simulation results are presented to validate the theoretical analysis and point out: (1) The secrecy performance of the considered network is affected by the channel fading scenario, the system configuration; (2) Decrease of the relay coverage airspace can provide better SOP performance; (3) Jamming from the relay can improve secrecy performance without additional network resources.

• Animal Systematics, Evolution and Diversity
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• 제23권1호
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• pp.69-74
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• 2007

First zoea of cyclograpsinine crab Chasmagnathus convexus (De Haan, 1835) belonging to the family Varunidae, is described and illustrated in detail based on laboratory-hatched material from an ovigerous female collected in Seumjingang river mouth, southern Korea. Morphological comparison is made with previous description of C. convexus from Japan, The first zoea of C. convexus can be readily distinguished from those of six species of Cyclograpsus intermedius Ortmann, 1894, Helicana japonica (K. Sakai and Yatsuzuka, 1980), Helicana wuana (Rathbun, 1931), Helice tientsinensis Rathbun, 1931, Helice tridens (De Man, 1835), and Pseudohelice quadrata (Dana, 1851), the other known cyclograpsinine species in Korea by having the lateral carapace spine, a pair of dorsolateral processes on the fourth abdominal somite, the exopod of antenna with three setae, and the exopod of antenna as being 24.7% length to the protopod.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2005년도 종합학술발표회 논문집 Vol.15 No.1
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• pp.289-292
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• 2005

Two planar inverted-F antenna (PIFA) arrays are proposed as an alternative model to generate input and radiation characteristics of two orthogonal oriented circular loops, which has polarization diversity, but inherent mechanical instability of two orthogonal loops, in particular, in installation and operation conditions. Two $1\times2$ PIFA sub-arrays are orthogonally placed on a ground plane and two different feeding networks are applied to control horizontal and vertical radiation current flows for each sub-array, respectively. Equivalence of scattering parameters and radiation patterns between two antennas are validated by the available commercial simulator.

• Animal Systematics, Evolution and Diversity
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• 제33권4호
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• pp.228-234
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• 2017

The first zoeas of Nursia rhomboidalis and Pyrhila carinata were obtained from laboratory condition. They are described and illustrated for the first time. Morphological comparison with those of other Korean described species of the family Leucosiidae reveals that the zoea of N. rhomboidalis is very similar to those of Myra fugax and Arcania undecimspinosa based on characteristics of the carapace spines length, the antenna morphology, the maxilla endopod setation, and the telson, whereas, the zoea of Py. carinata coincides well with those of Philyra kanekoi and Pyrhila pisum based on characteristics of the carapace spines length, the antenna morphology, the maxilla endopod setation, and the telson. Furthermore, we find that at least two groups of zoeas exist in the Korean species of the subfamily Ebaliinae. A provisional key to the known zoeas of ten leucosiid species from Korean waters is provided.

• 한국멀티미디어학회논문지
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• 제19권3호
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• pp.620-625
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• 2016

In this paper, we offer the secrecy outage probability of the amplify-and-forward (AF) transmission, which consists of one source, one destination, one relay, and one passive eavesdropper. Particularly, we consider that the relay is equipped with multiple antennas while other terminals is utilized with single antenna and apply diversity techniques (for both the reception and the transmission) at the relay to achieve gains in a secrecy outage performance. Additionally, we analyze the exact secrecy outage probability of the proposed systems in a one-integral form. Finally, some numerical examples are given to verify our provided analytical results for different system conditions.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 I
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• pp.202-205
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• 2003

The performance of space-frequency trellis coded (SFTC) OFDM system is analyzed in frequency selective fading channel. Using a pairwise error probability upper bound expression, we design the code and interleaver that can maximize the diversity and coding gain. To alleviate the performance degradation due to the inter-antenna product terms, we propose a new SFTC scheme that employs non-overlapped interleaving for each antenna A new code is optimized for the non-overlapped interleaving and a practical sub-optimal decoding algorithm is proposed. It is shown that the proposed scheme can substantially improve the performance compared to the conventional scheme that employs identical interleaving for all antennas.

• ETRI Journal
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• 제40권5호
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• pp.592-603
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• 2018

In order to obtain better target identification performance, an efficient waveform design method with high range resolution and low sidelobe level for orthogonal frequency division multiplexing (OFDM) multiple-input multiple-output (MIMO) radar is proposed in this paper. First, the wideband CP-based OFDM signal is transmitted on each antenna to guarantee large bandwidth and high range resolution. Next, a complex orthogonal design (COD) is utilized to achieve code domain orthogonality among antennas, so that the spatial diversity can be obtained in MIMO radar, and only the range sidelobe on the first antenna needs suppressing. Furthermore, sidelobe suppression is expressed as an optimization problem. The integrated sidelobe level (ISL) is adopted to construct the objective function, which is solved using the Broyden-Fletcher-Goldfarb-Shanno (BFGS) algorithm. The numerical results demonstrate the superiority in performance (high resolution, strict orthogonality, and low sidelobe level) of the proposed method compared to existing algorithms.