• Annual Conference of KIPS
• /
• 2003.05b
• /
• pp.1373-1376
• /
• 2003

본 논문에서는 DS-CDM-QPSK방식 위성 DAB 시스템(ITU-R BO. 1130-4 시스템 E)의 위성 중계기 고출력 증폭기(HPA) 비선형 특성으로 인한 전력효율 저하를 개선하기 위해 QPSK 변조기법 대신 부드러운 위상천이와 진폭변이가 적은 SQAM 변조기법을 적용한 DS-CDM-SQAM (Superposed Quadrature Amplitude Modulation) 방식을 제안하고 성능을 분석하였다. 비선형 다중경로 이동수신 환경에서 전산모의 실험 결과, 제안하는 DS-CDM-SQAM 방식은 기존의 DS-CDM-QPSK 방식보다 $BER=1{\times}10^{-3}$에서 Eb/No=1.7dB 성능 향상됨을 확인할 수 있었다. 따라서 DS-CDM-SQAM 시스템은 비선형 육상 이동 위성 DAB환경에서 전력효율을 크게 향상할 수 있다.

• Journal of Power Electronics
• /
• v.18 no.1
• /
• pp.137-146
• /
• 2018

This paper describes a single pulse-width modulation control strategy using the Single Pulse-Width Modulation (SPWM) method with a soft-switching technique for a wide range of output voltages from a bidirectional Dual-Active Bridge (DAB) converter. This method selects two typical inductor current waveforms for soft-switching, and proposes a rule that makes it possible to achieve soft-switching without any compensation algorithm from the waveforms. In addition, both the step-up and step-down conditions are analyzed. This paper verifies that the leakage inductance is independent from the rule, which makes it easier to apply in DAB converters. An integrated algorithm, which includes step-up and step-down techniques, is proposed. The results of experiments conducted on a 50-kW prototype are presented. The system efficiency is experimentally verified to be from 85.6% to 97.5% over the entire range.

• Proceedings of the KIPE Conference
• /
• 2014.07a
• /
• pp.197-198
• /
• 2014

본 논문에서는 양방향 DC-DC Dual Active Bridge (DAB) 컨버터의 수학적 모델로부터 컨버터의 변압기와 결합 인덕터의 최적 설계 방법을 제안한다. DAB컨버터는 1차 측과 2차 측이 동일한 구조를 가진 고효율 절연형 컨버터로써, Soft Switching이 쉽게 구현되고, 양방향으로 Power를 전달 할 수 있는 장점으로 널리 사용되고 있다. 본 논문에서 제안하는 컨버터는 Solid State Transformer (SST) 용으로 변압기 1차 측과 2차 측의 턴 비가 동일한 구조로써, 최대의 ZVS영역을 확보하고, 전력 변환 효율을 극대화 할 수 있다. 3.3 kW급 시제품을 제작하여 제안하는 컨버터의 타당성을 검증하고자 한다.

• Journal of Navigation and Port Research
• /
• v.28 no.3
• /
• pp.213-219
• /
• 2004

In this paper, a LNA(Low Noise Amplifier) has been developed, which is operating at L-band i.e., 1452∼1492 MHz for satellite DAB(Digital Audio Brcadcasting) receiver. The LNA is designed to improve input and output reflection coefficient and VSWR(Voltage Standing Wave Ratio) by balanced amplifier. The LNA consists of low noise amplification stage and gain amplification stage, which make a using of GaAs FET ATF-10136 and VNA-25 respectively, and is fabricated by hybrid method. To supply most suitable voltage and current, active bias circuit is designed Active biasing offers the advantage that variations in $V_P$ and $I_{DSS}$ will not necessitate a change in either the source or drain resistor value for a given bias condition. The active bias network automatically sets $V_{gs}$ for the desired drain voltage and drain current. The LNA is fabricated on FR-4 substrate with RF circuit and bias circuit, and integrated in aluminum housing. As a reults, the characteristics of the LNA implemented more than 32 dB in gain. 0.2 dB in gain flatness. lower than 0.95 dB in noise figure, 1.28 and 1.43 each input and output VSWR, and -13 dBm in $P_{1dB}$.

• Journal of Digital Convergence
• /
• v.12 no.3
• /
• pp.269-275
• /
• 2014

The DAB system was designed to provide CD quality audio and data services for fixed, portable and mobile applications with the required BER below $10^{-4}$. However for the T-DMB system with the video service of MPEG-4 stream, BER should go down $10^{-8}$ by adding FEC blocks which consist of the Reed-Solomon (RS) encoder/decoder and convolutional interleaver/deinterleaver. In this paper we propose two types of turbo coded T-DMB system without altering the puncturing procedure and puncturing vectors defined in the standard T-DMB system for compatibility. One(Type 1) can replace the existing RS code, convolutional interleaver and RCPC code by a turbo code and the other one (Type 2) can substitute the existing RCPC code by a turbo code. Simulation results show that two new turbo coded systems are able to yield considerable performance gain after just 2 iterations. Type 2 system is better than type 1 but the amount of performance improvement is small.

• Journal of Power Electronics
• /
• v.16 no.5
• /
• pp.1650-1660
• /
• 2016

This paper proposes a compensator to eliminate the DC bias of inductor current. This method utilizes an average-current sensing technique to detect the DC bias of inductor current. A small signal model of the DC bias compensation loop is derived. It is shown that the DC bias has a one-pole relationship with the duty cycle of the left side leading lag. By considering the pole produced by the dual active bridge (DAB) converter and the pole produced by the average-current sensing module, a one-pole-one-zero digital compensation method is given. By using this method, the DC bias is eliminated, and the stability of the compensation loop is ensured. The performance of the proposed compensator is verified with a 1.2-kW DAB converter prototype.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2002.11a
• /
• pp.201-206
• /
• 2002

패킷 기반 통신 시스템에서는 비트오율 보다는 패킷오율이 시스템 파라미터 설계에 보다 중요한 역할을 한다. 패킷오율을 분석하기 위해서는 대부분의 접근이 패킷을 이루고 있는 비트열의 오류 발생 사건을 독립이라고 가정한다. 그러나 실제의 통신 시스템에서는 오류 발생 형태가 버스트 형태로 그룹을 이루고 있다[1]. 본 논문은 비터비 디코더를 포함하는 통신시스템에 있어서의 버스트의 확률 분포를 기반으로 한 PER 모델을 제안하고, Eureka-147 방식의 디지털 오디오 방송 시스템의 시뮬레이션을 통하여 얻은 비트열에 대한 패킷오율과 제안한 패킷오율 모델과의 비교를 통하여 제안한 모델을 검증하였다.

• ETRI Journal
• /
• v.33 no.6
• /
• pp.969-972
• /
• 2011

This letter presents a CMOS RF front-end operating in a subthreshold region for low-power Band-III mobile TV applications. The performance and feasibility of the RF front-end are verified by integrating with a low-IF RF tuner fabricated in a 0.13-${\mu}m$ CMOS technology. The RF front-end achieves the measured noise figure of 4.4 dB and a wide gain control range of 68.7 dB with a maximum gain of 54.7 dB. The power consumption of the RF front-end is 13.8 mW from a 1.2 V supply.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.20 no.1
• /
• pp.110-115
• /
• 2021

A multi-band, compact, and complex vehicle roof antenna has become important in terms of car exterior design and multi-functions which include Radio, DAB/DMB, SXM, GNSS, Telematics, and V2X. In this paper, we propose a compact multi-band V2X pole-type roof antenna. Using impedance change characteristic, a single pole antenna which has multiband such as radio, DAB/DMB, telematics, and V2X band is proposed. With two patch antennas for GNSS and SXM, the dimension of a multiband roof antenna is 131x63x37mm only.

• Asian-Australasian Journal of Animal Sciences
• /
• v.33 no.3
• /
• pp.501-505
• /
• 2020

Objective: The purpose of this study was to investigate the effects of aging methods (AM) i.e. dry-aging (DA) and wet-aging (WA) on the physicochemical properties and in vitro digestibility of proteins in beef short loin. Methods: Short loins (M. longissmus lumborum), were trimmed and boned-out on the fifth day postmortem, from a total of 18 Hanwoo, which were purchased from a commercial slaughterhouse. Short loins were separated randomly grouped into one of the three treatments: control, WA (1℃, 7 days), and DA (1℃, 0.5 m/s, 85% relative humidity [RH], 30 days). Results: Dry-aged beef (DAB) exhibited higher pH, water holding capacity (WHC), myofibrillar fragmentation index (MFI), and digestibility, however lower lightness, redness, and yellowness values, cooking loss, and shear force (SF), than those of wet-aged beef (WAB) (p<0.05). The myosin light chain band intensity of DAB was higher than that of control and WAB in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The in vitro digestibility of aged beef was highly (p<0.001) correlated to physicochemical properties except WHC. The correlation coefficient between AMs and WHC was higher than that between AM and SF (p<0.05) or MFI (p<0.001). A high correlation was observed between SF and MFI (p<0.001). Conclusion: Thus, we believe that DAB is more advantageous than WAB owing to its high digestibility and WHC and low SF.