• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.363-365
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• 2002

train radio system used for shinkansen in japan has been 18 years since it was opened in 1982 and grown old. Analogue train radio is short of the number of lines and can't cope with the needs for the new high speed data transmission by 1,200 bps. The construction to renew the Tohoku - Joethu shinkansen train radio system(shinkansen train radio system) with digital method started from 2000 in JREast Digital method makes it possible to improve the quality of radio transmission, reliability of the network and every device, the speed and capacity of transmission and to be more efficient maintenance by introducing the latest IT technology. This paper will consider synchronization between base station. diversity method. software receiver, mobile high speed digital radio system, high reliability LAN introduced as technologies supporting these.

• Journal of electromagnetic engineering and science
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• 제18권4호
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• pp.254-260
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• 2018

In this study, we suggest an emulator for generating multiple heterogeneous interference signals in the Korean radio frequency identification/ubiquitous sensor network (RFID/USN) frequency band. The proposed emulator uses only one universal software radio peripheral to generate multiple heterogeneous interference signals more economically. Moreover, the physical and media access control parameters can be adjusted in real time using the LabVIEW program, thereby making it possible to create various time-varying interference environments easily. As an example showing the capability of the proposed emulator, multiple interference signals consisting of a frequency-hopping RFID signal and two LoRa signals with different spreading factors were generated. The generated signals were confirmed in both frequency and time domains. From the experimental results, we verified that our emulator could successfully generate multiple heterogeneous interference signals with different frequency and time domain characteristics.

• Journal of Communications and Networks
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• 제10권1호
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• pp.55-62
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• 2008

Bandpass sampling (BPS) techniques for the direct down-conversion of RF bandpass signals have become an essential technique for software defined radio (SDR), due to their advantage of minimizing the radio frequency (RF) front-end hardware dependency. This paper proposes an algorithm for finding the minimum BPS frequency for simultaneously down-converting multiple RF signals through full permutation over all the valid sampling ranges found for the multiple RF signals. We also present a scheme for reducing the computational complexity resulting from the large scale of the purmutation calculation involved in searching for the minimum BPS frequency. In addition, we investigate the BPS frequency allowing for the guard-band between adajacent down-converted signals, which help lessen the severe requirements in practical implementations. The performance of the proposed method is compared with those of other pre-reported methods to prove its effectiveness.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권2호
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• pp.787-806
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• 2016

Traditional radio-based gesture recognition approaches usually require the target to carry a device (e.g., an EMG sensor or an accelerometer sensor). However, such requirement cannot be satisfied in many applications. For example, in smart home, users want to control the light on/off by some specific hand gesture, without finding and pressing the button especially in dark area. They will not carry any device in this scenario. To overcome this drawback, in this paper, we propose three algorithms able to recognize the target gesture (mainly the human hand gesture) without carrying any device, based on just Radio Signal Strength Indicator (RSSI). Our platform utilizes only 6 telosB sensor nodes with a very easy deployment. Experiment results show that the successful recognition radio can reach around 80% in our system.

• 융합신호처리학회논문지
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• 제16권4호
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• pp.175-181
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• 2015

본 논문은 전파천문 관측데이터 분석을 위해 소프트웨어를 이용한 디지털필터 설계방법에 대해 제안한다. 전파천문 관측시스템은 컴퓨팅 시스템의 발전과 함께 하드웨어에서 소프트웨어를 이용한 분석방법으로 넘어가는 단계이다. 기존 하드웨어로는 특정규격에 맞도록 설계 제작되었기 때문에 규격을 변경하는 것이 어렵고 제작에 많은 비용이 소요되지만, 소프트웨어는 규격 변경이 유연하고 공개 소프트웨어를 이용할 경우 저렴하게 설계할 수 있는 장점이 있다. 그러나 소프트웨어로 전파천문과 같이 많은 자료를 분석하기 위해서는 컴퓨터 시스템의 성능이 우수해야 하는 점도 있다. 본 연구에서는 한국우주전파관측망에서 운영하고 있는 관측시스템 중에서 하드웨어로 구성된 디지털필터와 같은 성능을 갖는 소프트웨어 디지털 필터 설계에 대해 제안한다. 제안 방법은 표준 C언어를 이용하여 디지털 필터를 설계하였으며, 설계한 디지털필터에 대해 GNU Octave로 시뮬레이션을 수행하여 유효성을 검토하였다. 또한 설계한 디지털필터의 고속연산을 위해 병렬연산이 가능한 SSE 라이브러리를 도입하였다. KVN 관측모드 중에 광대역 관측데이터를 대상으로 제안한 방법의 디지털 필터를 통하여 협대역 관측모드로 데이터 필터링을 수행하였다. 그 결과, 대역 내의 필터링이 설계대로 수행되었고 리플이 발생하지 않아, 제안방법이 유효함을 확인하였다.

• 천문학회보
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• 제36권2호
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• pp.82.1-82.1
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• 2011

Korea Astronomy and Space Science Institute (KASI) operates 2 solar radio observing facilities, e-CALLISTO (Earthwide network of Compound Astronomical Low-cost Low-frequency Instrument for Transportable Observatory) station and Korean Solar Radio Burst Locator (KSRBL). Although e-CALLISTO tracking system improvement.is underway, at least 6 new events were observed in this year. Software development for KSRBL is in progress. The antenna calibration software was updated and flux calibration software was developed. Also the automatic daily overview spectrum monitoring system is now operational. We found solutions to several problems including spurious data and FPGA board communication. However, a few minor unsolved hardware problems still persist. Meanwhile, at least 6 new events were observed by KSRBL in this year, and a comparative study with HXR is currently underway.

• 한국통신학회논문지
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• 제33권5A호
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• pp.494-499
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• 2008

본 논문은 SDR(Software Defined Radio) 기술을 기반으로 CDMA(Code Division Multiple Access) 방식의 이동전화 시스템과 같은 다중 채널 처리 시스템에서 특정 FA(frequency Assignment)만을 여파하여 처리하는 다양한 응용에 적용될 수 있는 디지털 필터 기법을 제안한다. 이 기법은 마이크로 프로세서를 이용하여 사용자가 선택하는 특정 시스템 정보에 따라 소프트웨어적으로 필터 계수(Filter Coefficients)를 재설계하여 한 개의 디지털 FIR(Finite Impulse Response) 대역통과 필터(BPF: Band Pass Filter)를 재구성함으로써 여러 개의 대역통과 필터를 갖는 효과를 얻는다. 본 논문에서 제안하는 기법을 적용하여 다중채널 신호 발생기를 구현하고, 동일한 하드웨어 상에서 WCDMA(Wideband Code Division Multiple Access) 시스템 혹은 CDMA 시스템으로 재구성하는 시험을 통하여 본 알고리즘의 구현 가능성을 검증하였다.

• 한국군사과학기술학회지
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• 제17권1호
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• pp.57-63
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• 2014

In this paper, we have proposed a wide band antenna for manpack SDR(Software Defined Radio). The proposed antenna consists of feeding post, flexible gooseneck and two radiating elements composed of a upper and lower radiators. The upper radiator has a longer electrical length than the lower radiator in order to operate in the lower frequency. Also, the resonant frequency and impedance characteristics of the antenna can be adjusted independently for two radiators. Therefore, the proposed antenna can be achieved wide impedance bandwidth by the combination of two independent resonance modes. To analyze the characteristics of the antenna in the design process is employed the equivalent circuit theory and EM(Electro-Magnetic) simulation. The measurement results show that the proposed antenna have the sufficient wide bandwidth, above -3.4dBi of the gain and fairly good radiation pattern over the wide bandwidth.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2008년도 한국컴퓨터종합학술대회논문집 Vol.35 No.1 (A)
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• pp.53-54
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• 2008

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2008년도 한국컴퓨터종합학술대회논문집 Vol.35 No.1 (A)
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• pp.29-30
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• 2008