• 대한임베디드공학회논문지
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• 제15권4호
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• pp.159-166
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• 2020

The IBC (Intra-Body Communication) benefits from a wireless communication system for exchanging various kinds of digital information through wearable electronic devices and sensors. The IBC using the human body as the transmission channel allows wireless communication without the transmitting radio frequency waves to the air. This paper discusses the results of experiments on electrostatic coupling IBC based on FSK (Frequency Shift Keying) and 1 bit error correction. We implemented FSK communication and 1 bit error correction algorithm using the MCU boards and aluminum tape electrodes. The transmitter modulates digital data using 50% duty square wave as carrier signal and transmits data through human body. The receiver performs ADC (Analog to Digital Conversion) on carrier signal from human body. In order to figure out the frequency of carrier signal from ADC results, we applied zero-crossing algorithm which is used to detect the edge characteristic in computer vision. Experiment results shows that digital data modulated as square wave can be successfully transmitted through human body by applying the proposed architecture of a 1ch GPIO as a transmitter and 1ch ADC for as a receiver. Also, this paper proposes 1 bit error correction technique for reliable IBC. This technique performs error correction by utilizing the feature that carrier signal has 50% duty ratio. When 1 bit error correction technique is applied, the byte error rate at receiver side is improved around 3.5% compared to that not applied.

• 한국전자파학회논문지
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• 제19권8호
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• pp.854-861
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• 2008

본 논문에서는 효율이 특화된 전력 증폭기를 이용하여 IEEE 802.16e Mobile WiMAX용 고출력 하이브리드 포락선 제거 및 복원 전력 송신기에 대해 기술하였다. Nitronex사의 100-W PEP를 갖는 GaN HEMT 소자를 이용하여 중요한 전력 생성 $V_{ds}$ 구간에 대하여 최대 PAE를 가질 수 있도록 전력 증폭기를 설계하였다. 고출력 응용을 위해서 하이브리드 포락선 제거 및 복원 전력 송신기를 전력 증폭기의 bias fluctuation 문제 및 바이어스 변조기의 stability 문제에 의한 regenerative 오실레이션 문제를 반드시 고려하여 설계되어야 한다. 연동 실험을 위하여, 8.5 dB의 PAPR을 갖는 포락선 신호에 대해 바이어스 변조기는 30 V의 최대 출력 전압 크기를 가지면서 72 %의 높은 효율을 유지하도록 구현되었다. WiMAX 신호를 목표로 구현된 하이브리드 포락선 제거 및 복원 전력 송신기는 41.25 dBm의 출력 전력에서 38.8%의 놓은 PAE 성능을 얻었다. 또한, 디지털 전치 왜곡 기술을 적용함으로써 전력 송신기의 RCE 성능은 -34.5 dB를 기록하여 WiMAX 신호의 선형화 지표를 만족시킬 수 있었다. 본 연구는 2.655 GHz 주파수 대역에서 처음으로 구현된 WiMAX용 고출력 하이브리드 포락선 제거 및 복원 전력 송신기에 관한 것이다.

• 전자공학회논문지B
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• 제33B권3호
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• pp.62-68
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• 1996

A CMOS transmitter ASIC for the ATM switching system etc., was designed to transmit 155.52 Mbps serial data transformed from 19.44 Mbps parallel data. 155.52 MHz clock for synchronization of data is genrated using reference 19.44 MHz clock by an analog PLL while parallel to serial data conversion is done by a digital circuit. Circuit simulations confirm that PLL locking and data conversion are accomplished successfully. The area of the designed ASIC chip is 1.3${\times}1.0mm^2$. The locking time and the power consumption of the chip are about 600 nsec and less than 150 mW, respectively.

• 센서학회지
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• 제14권3호
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• pp.150-155
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• 2005

We propose a newly developed automobile sensor monitoring system incorporated with a tire pressure monitoring sensor(TPMS). The RF-transmitter based on a tire pressure sensor, sends a frame data about measured tire-pressure to RF receiver. And the various sensing signals based on sensors such as fuel-level sensor, engine oil level sensor and temperature sensors, are converted into 10-bit digital data. The microprocessor displays converting data such as tire pressure, trip distance, fuel quantity, coolant temperature and car-room temperature, on LCD panel. The proposed system can be successfully adapted to monitoring of the tire pressure and various automobile sensors.

• ETRI Journal
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• 제34권2호
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• pp.168-174
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• 2012

In Advanced Television Systems Committee (ATSC) terrestrial digital television (DTV) systems, additional very low-rate data can be transmitted by modulating the amplitude and polarity of the transmitter identification (TxID) signal. Although the additional data transmission scheme offers reliable transmission and has a very large coverage area, it has a limitation on the data rate. In this paper, we propose a novel additional data transmission scheme based on the TxID sequences of the ATSC DTV system and Walsh modulation. The proposed scheme not only increases the data rate significantly, but also offers a virtually identical coverage area compared to a conventional scheme.

• 전자공학회논문지A
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• 제33A권3호
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• pp.47-54
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• 1996

In this paper we propose a new timing recovery method by means of utilizing service data filling rate instead of timing information of transmitter. A proposed algorithm controls the phase locked loop in the opposite direction ot data filling rate of FIFO in receiver, and it is based on the fact that average of cell jitters is zero. The proposed method is simple compared with timing information method of transmitter. It can be utilized for timing recovery in synchronous digital hierarchy as well as in plesiochronous digial hierarchy without common reference clocks in end-to-end erminals. We implement the interactive video communication system and test the proposed algorithm. As a result, we hav econfirmed that it yields good perfomrnces in terms of jitters characteristics and hardware complexity.

• Journal of information and communication convergence engineering
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• 제17권3호
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• pp.221-226
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• 2019

In this work, a transmitter/receiver front-end module (T/R FEM) with an automatic Tx/Rx switching scheme for a 2.4 GHz microwave power transfer is developed for a retro-reflective beamforming scheme. Recently, research on wireless power transfer techniques has moved to wireless charging systems for mobile devices. Retro-reflective beamforming is a good candidate for tracking the spatial position of a mobile device to be charged. In Tx mode, the T/R FEM generates a minimum of 1 W. It also comprises an amplitude and phase monitoring port for transmitting RF power. In Rx mode, it passes an Rx pilot signal from a mobile device to a digital baseband subsystem to recognize the position of the mobile device. The insertion loss of the Rx signal path is 4.5 dB. The Tx and Rx modes are automatically switched by detecting the Tx input power. This T/R FEM is a design example of T/R FEMs for wireless charging systems based on a retro-reflective beamforming scheme.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 제13회 신호처리 합동 학술대회 논문집
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• pp.229-232
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• 2000

Orthogonal frequency division multiplexing(OFDM) has meanwhile become part of several telecommunicati ons standards, such as satellite and terrestrial digital audio broadcasting(DAB), digital terrestrial TV broad casting(DVB), asymmetric digital subscriber line(ADSL) for high-bit-rate digital subscriber services on twisted-pair channels, and broadband indoor wireless systems. In his paper, we show that OFDM signals contain sufficient structure to accomplish blind channel estimation using second order statistics only. This method doesn't require redundancy as cp in transmitter. And the result is compared with PSAM channel estimation as least square, linear minimum mean square, singular value decomposition.

• 정보학연구
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• 제4권4호
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• pp.25-35
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• 2001

본 논문은 문서상에 서명을 직접 합성하는 문서화상에 대한 디지털 서명 구조를 제안한다. 서명에 소요되는 시간은 서명의 확산에 의해 감축된다. 본 구조에 의해 디지털 서명의 제 3 조건인 발신 부인 봉쇄가 실현된다. 발신자가 비밀리에 서명을 합성하여 전송하면 수신자는 서명과 문서상의 오류를 확인 할 수 있다. 본 구조는 ITU-T.4 규격과 호환한다.

• 한국통신학회논문지
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• 제21권9호
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• pp.2456-2469
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• 1996

A digital satellite communication channel has a nonlinearity with memory due to saturation characeristis of the high poer amplifier in the satellite and transmitter/receiver linear filter used in the overall system. In this paper, we propose a complex radial basis function network(CRBFN) based adaptive equalizer for compensation of nonlinearities in digital satellite communication channels. The proposed CRBFN untilizes a complex-valued hybrid learning algorithm of k-means clustering and LMS(least mean sequare) algorithm that is an extension of Moody Darken's algorithm for real-valued data. We evaluate performance of CRBFN in terms of symbol error rates and mean squared errors nder various noise conditions for 4-PSK(phase shift keying) digital modulation schemes and compare with those of comples pth order inverse adaptive Volterra filter. The computer simulation results show that the proposed CRBFN ehibits good equalization, low computational complexity and fast learning capabilities.