• Journal of Satellite, Information and Communications
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• v.5 no.2
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• pp.97-103
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• 2010

In this paper, we present an efficient design scheme based on analysis of design requirements and considerations of baseband packet switch for S-band satellite/terrestrial hybrid multi-beam satellite communication systems. To establish design requirements and considerations, we analyze required functions of baseband packet switch, specifications of multi-beam satellite communications, communication services and performance requirements. And also we analyze and compare conventional layer-2 and layer-3 satellite baseband packet switching techniques, packet switching protocols and packet switch architectures, to apply from analyzed results. Finally, we propose a hardware design scheme of MPEG based layer-2 baseband packet switch using analyzed results.

• Journal of Satellite, Information and Communications
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• v.12 no.2
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• pp.89-93
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• 2017

This paper introduces an energy harvesting system that generates energy by collecting multi-band RF signals using buck-boost DC-DC converter. In an environment where the resistance of load using the collected electric energy is constantly changing, a buck-boost DC-DC converter is used in which the input resistance of the DC-DC converter does not change even if the load resistance changes. Since the frequency band of the input RF signal varies, the rectifier is designed for each band so that multiple bands can be processed, and a matching circuit is added to each band in front of the rectifier. For a rectifier to collect very small RF signals, a circuit is designed so that a constant voltage is obtained according to a very small input signal by devising a method of continuously accumulating the voltages collected and generated in each band. It is confirmed that the output efficiency can reach up to 20% even for the RF signal having the input of -20 dBm.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.7 no.3
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• pp.48-55
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• 2008

This paper presents a design of a multi-band infernal antenna for mobile handsets which can cover the major mobile services such as WiBro/WiMAX mobile internet services and Media-FLO/S-DMB services. Using wideband monopole antenna structure, the proposed antenna obtains the wide bandwidth characteristic at high Sequency band to be applicable for new mobile services. Stacking meandered radiator on the wideband monopole radiator and obtaining the different current path and lenga on these stacked radiators, overall antenna volume is effectively reduced. The measured bandwidths (VSWR<3) of the proposed antenna is 270 MHz and 2032 MHz at low and high band, respectively. This antenna can effectively covers major wireless communication bands including Media-FLO, CDMA, GSM, GPS, DCS, PCS, UMTS, WiBro, WiMAX, and S-DMB.

• The Journal of the Acoustical Society of Korea
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• v.38 no.1
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• pp.23-29
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• 2019

In this paper, a deep learning-based detection and classification using multi-band frequency signals is presented for detecting earthquakes prevalent in Korea. Based on an analysis of the previous earthquakes in Korea, it is observed that multi-band signals are appropriate for classifying earthquake signals. Therefore, in this paper, we propose a deep CNN (Convolutional Neural Network) using multi-band signals as training data. The proposed algorithm extracts the multi-band signals (Low/Medium/High frequency) by applying band pass filters to mel-spectrum of earthquake signals. Then, we construct three CNN architecture pipelines for extracting features and classifying the earthquake signals by a late fusion of the three CNNs. We validate effectiveness of the proposed method by performing various experiments for classifying the domestic earthquake signals detected in 2018.

• Journal of Satellite, Information and Communications
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• v.9 no.1
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• pp.38-44
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• 2014

In this paper, we designed a multiband monopole antenna for next-generation WLAN system. In conventional WLAN system, UWB antennas were used together, and, because the radiation occurs in different parts depending on the antenna structure, it has the disadvantage of having an unstable impulse response characteristic due to dispersion characteristics. Although a UWB antenna that has suitable radiation pattern for WLAN band, it does not have good impedance matching and has severe echo. Therefore, in this paper, a monopole antenna was designed by using CPW power feed so that various impedances can be easily implemented when designing an antenna and more parameters can be derived that can be used for design for optimal performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37B no.11
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• pp.1072-1081
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• 2012

For Ka-band satellite communication system, a new flexible payload technologies which can compensate rain attenuation have to be developed. The Ka-band satellite output power control technology enables to adjust downlink output power of satellite payload in Ka-band (19.8 ~ 22.2 GHz). In this paper, we introduce multi-beam antenna with multi-port amplifiers for Ka-band flexible output power allocation system. We have designed multi-beam antenna with array-fed reflector to form 8 beams on the Korean Peninsula. The target EIRP per beam is more than 59 dBW. The system is designed to present 6 dB boost beams for rainfall areas. Individual beams were optimized by the excited amplitude and phase of feed elements of the feed cluster. The multi-port amplifier(MPA) is one of effective approaches for flexible power allocation in combination with multi-beam antenna. In case of using MPA in multi-beam system, the inter-port isolation characteristic of MPA is important parameter to avoid interference among the output ports. In this paper, we propose a new MPA structure that consists of two $4{\times}4$ Buttler matrixes and phase/amplitude controllable power amplifier modules.

• Journal of Digital Contents Society
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• v.18 no.6
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• pp.1207-1211
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• 2017

Long-Reach PON (LR-PON) is a broadband access network using passive optical network (PON) technology which the reach is extended to 100 km or higher. A major challenge in LR-PON is that the propagation delay between OLT and ONUs is increased by a very significant amount. To effectively and fairly distribute the upstream bandwidth dynamically in LR-PON, we propose a new periodic and multi-thread polling based dynamic bandwidth allocation (DBA) algorithm. We compare the proposed algorithm with traditional DBAs and show its advantage on average packet delay. Numerical results are analyzed under varying offered loads.

• 한국정보통신설비학회:학술대회논문집
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• 2002.08a
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• pp.17-20
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• 2002

본 논문에서는 세라믹 칩 안테나를 LTCC로 구현하여 다중 대역 특성을 얻는 방법을 제안하고 있다. 휴대용 단말기에 칩 안테나를 내장함으로 물리적 손상을 피하고 위치추적 시스템(GPS) 대역과 단말기 송수신용 대역, 즉 두 대역 이상 사용 가능하고 ${\varepsilon}_r=7.8$인 세라믹 칩 안테나를 LTCC(Low Temperature Co-fired Ceramic)공정을 이용하여 세라믹 칩 내부에 정합 회로를 구현하여 이중 대역 특성을 갖는 구조에 대해 논의하고 있다. 안테나의 전체 크기는 $16mm{\times}4mm{\times}2mm$ 이며 대역폭은 삽입손실 -10dB 기준 대략 1560MHz에서 2160MHz까지 약 600MHz정도이다. 측정은 접지면의 넓이가50mmx50mm이고 두께=0.7874mm, ${\varepsilon}_r=4.6$인 FR4 기판을 이용하여 측정한다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.5
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• pp.93-97
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• 2022

Infrared scenes usually contain also spectral information which cannot be resolved using normal single-band infrared cameras. Multispectral infrared imaging cameras give access to the comprehensive information contained within infrared scenes. A Dual-band infrared Camera, a type of multispectral infrared imaging cameras, has the advantage of simple system. A Dual-band Infrared Camera gives access to the spectral information as wells as the temperature information within infrared scenes. Multispectral imaging generally increases the detection and identification performance of a Dual-band Infrared Camera. This paper describes a design of an infrared Camera using a Dual-band Infrared Detector to simultaneously receive infrared radiation from the medium-wave infrared/long-wave infrared(MWIR/LWIR) bands.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.5
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• pp.537-543
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• 2010

This paper presents a slot-shaped defected ground structure(DGS) which has multi-band rejection property. The proposed structure, in which the spiral slot-shaped defects with different size are aligned in the transverse direction to the guiding direction of the coplanar waveguide(CPW), provides multiple resonance frequencies. Compared with the simulated results, the band rejection characteristic is in good agreement with the measurement. Also, an equivalent circuit model of the proposed structure is presented, where the DGS on the ground plane is modeled as LC-resonators. This resonators are inductively coupled to the signal line through mutual inductance. From the equivalent circuit model, multi-band rejection property was derived.