• Journal of information and communication convergence engineering
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• 제21권1호
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• pp.1-8
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• 2023

This paper presents a design method for a wideband bandpass filter (BPF) which compensates for frequency dependency based on the image admittance and image phase. In the proposed method, new compensation methods for the admittance and phase are integrated with the conventional method. The proposed method improves the frequency shift and reduces the unwanted bandwidth when designing more than 20% of the Fractional Bandwidth (FBW), whereas the conventional method exhibits frequency degradation at only 10% FBW. The proposed design theory was verified by applying it to both lumped elements and distributed lines through circuit simulation and measurements without an optimization process. The measurement results demonstrate improvements in the frequency shift and target bandwidth. In the future, an accurate design method based on frequency dependence can be implemented for the next-generation broadband communication system applications.

• 한국정보통신학회논문지
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• 제20권5호
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• pp.874-879
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• 2016

본 논문에서는 직사각형 및 삼각형 기생 패치를 이용한 광대역 마이크로스트립 패치 안테나를 제안하였다. 직사각형 마이크로스트립 패치 위에 직사각형 및 삼각형 모양의 기생 패치들을 적층하여 860MHz대역에서 광대역 특성을 얻었다. 주 방사부인 마이크로스트립안테나와 기생 패치와의 효과적인 결합은 이들 사이에 두꺼운 공기층을 두어 구현하였다. 또한, 이들 공기층 두께와 기생 패치의 위치는 광대역 정합에 중요한 요소임을 알 수 있었다. 제안된 안테나는 향후 소형 트랜시버에 적용하기 위해 $119mm{\times}109mm$ 크기의 소형 접지면 위에 설계 및 제작되었다. FR4기판에 제작된 안테나의 임피던스 대역은 818~919MHz(11.7%)이다. 방사패턴은 기존 마이크로스트립 패치 안테나와 유사했으며, 최대 이득은 주파수 824MHz에서 2.11dBi로 측정되었다.

• International Journal of Computer Science & Network Security
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• 제24권4호
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• pp.206-210
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• 2024

Industrial facilities that use modern IT technologies require the ensured reliability and security of information in automated enterprise management. Concurrently, so as to ensure a high quality of communication, it is necessary to expand the bandwidth of communication channels, which are limited by the physical parameters of the radio frequency spectrum. In order to overcome this contradiction, we propose the application of technology fundamental to ultra-wideband signals, in which the ratio between the bandwidth and its central part is greater than "one". For this reason, the information signal is emitted without a carrier frequency - simultaneously within the entire frequency band - provided that the signal level is lower than the noise level. For the transmission of information content, the method of positional-time coding is used, in which each information bit is encoded by hundreds of ultrashort pulses that arrive within a certain sequence. Mathematical models of signals and values observed in wireless communication systems with autocorrelation reception of modulated ultra-wideband signals are furthermore recommended. These assist in identifying features of the dependence of the error probability on the normalized signal-to-noise ratio and the signal base. Comparative analysis has shown that the best noise immunity of the systems considered in this paper is the communication system, which uses the time separation of the reference and information signals. During the first half of the bit interval, the switch closes the output of the transmitter directly to the generator of the ultra-wideband signal - forming a reference signal. In the middle of the bit interval, the switch alternates the output to one of two possible positions depending on the encoding signal - "zero" or "one", forming the information part of the ultra-wideband signal. It should also be noted that systems with autocorrelation reception and separate transmission of reference and information signals, provide a high level of structural signal secrecy. Furthermore, they provide the reliable transmission of digital information, especially in interference conditions.

• 대한전기학회논문지:시스템및제어부문D
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• 제54권1호
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• pp.56-60
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• 2005

In the power-line communication(PLC) systems, the power line is a wired medium. However, the power line channel has the multi-path fading characteristics like the wireless channel in the wireless communication systems because it has the signal reflection and divergence by the impedance mismatching between many branch lines and loads. So the analysis of the multi-path characteristics is very important, and it has been doing by the several measurement methods for the impulse response between the transmitter and the receiver. PN sequence method has originally been used as a wideband impulse response measurement mettled for wireless channel, but it is recently being applied to not only the wireless channel but also the wired channel like the power line channel. This method is more useful and effective for the long distance communication channel like the medium voltage power distribution line with the multi-paths[1]. In this thesis, we have measured impulse response for the medium voltage power distribution line channel by the wideband measurement method using PN sequence, analytically studied the measured data and presented the results.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권7호
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• pp.2614-2632
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• 2015

A multiple symbol detection (MSD) algorithm is proposed relying on soft information for ultra-wideband systems, where differential space-time block code is employed. The proposed algorithm aims to calculate a posteriori probabilities (APP) of information symbols, where a forward and backward message passing mechanism is implemented based on the BCJR algorithm. Specifically, an MSD metric is analyzed and performed for serving the APP model. Furthermore, an autocorrelation sampling is employed to exploit signals dependencies among different symbols, where the observation window slides one symbol each time. With the aid of the bidirectional message passing mechanism and the proposed sampling approach, the proposed MSD algorithm achieves a better detection performance as compared with the existing MSD. In addition, when the proposed MSD is exploited in conjunction with channel decoding, an iterative soft-input soft-output MSD approach is obtained. Finally, simulations demonstrate that the proposed approaches improve detection performance significantly.

• 한국항행학회논문지
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• 제14권5호
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• pp.745-751
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• 2010

본 논문에서는 근거리 무선환경에서 초광대역 Impulse Radio 시스템과 기존의 협대역 통신 시스템의 주파수 공존을 위한 협대역 간섭 제거 기법을 제안하였다. 협대역 통신 시스템은 Impulse Radio 시스템의 주파수 대역에서 협대역 간섭의 원인이 될 수 있다. 따라서, 본 논문에서는 다중간섭 및 협대역 간섭 환경에서 Impulse Radio 통신 시스템의 간섭 영향을 분석하고, 효과적인 성능 개선을 위하여 복소다중 필터뱅크와 CCI 간섭제거기를 동시에 채용함으로써 수신성능의 개선을 얻을 수 있었다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권4호
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• pp.1795-1811
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• 2019

In order to achieve rapid and accurate detection of vehicle objects in complex traffic conditions, we propose a novel vehicle detection method. Firstly, more contextual and small-object vehicle information can be obtained by our Joint Feature Network (JFN). Secondly, our Evolved Region Proposal Network (EPRN) generates initial anchor boxes by adding an improved version of the region proposal network in this network, and at the same time filters out a large number of false vehicle boxes by soft-Non Maximum Suppression (NMS). Then, our Mask Network (MaskN) generates an example that includes the vehicle occlusion, the generator and discriminator can learn from each other in order to further improve the vehicle object detection capability. Finally, these candidate vehicle detection boxes are optimized to obtain the final vehicle detection boxes by the Fine-Tuning Network(FTN). Through the evaluation experiment on the DETRAC benchmark dataset, we find that in terms of mAP, our method exceeds Faster-RCNN by 11.15%, YOLO by 11.88%, and EB by 1.64%. Besides, our algorithm also has achieved top2 comaring with MS-CNN, YOLO-v3, RefineNet, RetinaNet, Faster-rcnn, DSSD and YOLO-v2 of vehicle category in KITTI dataset.

• 한국전자파학회논문지
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• 제13권4호
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• pp.366-372
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• 2002

L-스트립 급전선에 의해서 급전되는 광대역 적층 패치 안테나를 실험적으로 연구하였다. 본 논문의 목표는 PCS와 IMT-2000 서비스를 위한 소형 광대역 안테나를 설계하는데 있다. 실험결과에서 704.7 MHz(35.95 %)의 임피던스 대역폭(VSWR$\leq$2)이 PCS와 IMT-2000 주파수 대역에서 얻어지는 것을 확인하였다. 연구된 안테나는 단순한 구조 때문에 어레이 확장이 쉽게 설계될 수 있다.

• Journal of information and communication convergence engineering
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• 제14권3호
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• pp.184-190
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• 2016

We present experimental demonstrations of electromagnetic bandgap (EBG) structures for the wideband suppression of radiated emissions from a power bus in high-speed printed circuit boards (PCBs). In most of the PCB designs, a parallel plate waveguide (PPW) structure is employed for a power bus. This structure significantly produces the wideband-radiated emissions resulting from parallel plate modes. To suppress the parallel plate modes in the wideband frequency range, the power buses based on the electromagnetic bandgap structure with a defected ground structure (DGS) are presented. DGSs are applied to a metal plane that is connected to a rectangular EBG patch by using a via structure. The use of the DGS increases the characteristic impedance value of a unit cell, thereby substantially improving the suppression bandwidth of the radiated emissions. It is experimentally demonstrated that the DGS-EBG structure significantly mitigates the radiated emissions over the frequency range of 0.5 GHz to 2 GHz as compared to the PPW.

• 한국정보통신학회논문지
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• 제21권1호
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• pp.53-60
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• 2017

본 연구는 해상 인명구조를 위한 장거리, 광대역 멀티미디어 통신을 지원하는 드론을 설계하고 구현하는 것이다. 드론은 사람이 기계의 본체에 탑승하지 않고 무선전파의 유도에 의해서 조종이 가능한 무인항공기(UAV : Unmanned Aerial Vehicle)이다. 최근 증가하는 선박사고에 신속하게 대응하기 위하여 드론을 이용하고자 한다. 선박사고에 대응하기 위한 해상 장거리, 고속 영상 전송이 가능한 스마트 드론을 개발하기 위해서는 드론을 구조적으로 설계하는 하드웨어 설계부분과 개발된 드론을 동작시키기 위한 제어기술 그리고 원격지에서 드론을 제어하기 위한 통신기술등이 필요하다. 본 논문은 해상 장거리, 광대역 멀티미디어 통신을 지원하는 드론 구조를 설계하기 위한 제한사항과 요소기술을 정리하고 이를 위한 드론 구조를 설계 및 구현한다. 이러한 통신용 드론을 드론 네트워크로 확장함으로써 드론의 활용성을 확장하고자 한다.