• 한국재료학회:학술대회논문집
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• 한국재료학회 2011년도 춘계학술발표대회
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• pp.64.2-64.2
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• 2011

Recently, Silicon Germanium (SiGe) alloys have been received considerable attention for their great potentials in advanced electronic and optoelectronic devices. Especially, microcrystalline SiGe is a good channel material for thin film transistor due to its advantages such as narrow and variable band gap and process compatibility with Si based integrated circuits. In this work, microcrystalline silicon-germanium films (${\mu}c$-SiGe) were deposited by DC/RF magnetron co-sputtering method using Si and Ge target on Corning glass substrates. The film composition was controlled by changing DC and RF powers applied to each target. The substrate temperatures were changed from $100^{\circ}C$ to $450^{\circ}C$. The microstructure of the thin films was analyzed by x-ray diffraction (XRD) and Raman spectroscopy. The analysis results showed that the crystallinity of the films enhances with increasing Ge mole fraction. Also, crystallization temperature was reduced to $300^{\circ}C$ with $H_2$ dilution. Hall measurements indicated that the electrical properties were improved by Ge alloying.

• Journal of the Optical Society of Korea
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• 제18권6호
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• pp.739-745
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• 2014

We have demonstrated a $Ti:LiNbO_3$ electro-optic electric-field sensor utilizing a $1{\times}2$ Y-fed balanced-bridge Mach-Zehnder interferometric (YBB-MZI) modulator, which uses a 3-dB directional coupler at the output and has two complementary output waveguides. A dc switching voltage of ~25 V and an extinction ratio of ~12.5 dB are observed at a wavelength of $1.3{\mu}m$. For a 20 dBm rf input power, the minimum detectable electric fields are ~8.21, 7.24, and ~13.3 V/m, corresponding to dynamic ranges of ~10, ~12, and ~7 dB at frequencies of 10, 30, and 50 MHz respectively. The sensors exhibit almost linear response for an applied electric-field intensity from 0.29 V/m to 29.8 V/m.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.2397-2401
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• 2005

It is well understood that force reflecting coupled with visual display can be an important two-way communication channel in human-computer interaction. In this work, important components for a high-fidelity system bandwidth are force reflecting device and that all the computations including contact determination and response computation have to be performed in less than a millisecond. This paper describes a force-reflecting device and an embedded controller. The realized force-reflecting device is based on a novel serial type mechanical structure, and features compactness, high sustained output force capability, low friction, zero backlash, and enough workspace. The embedded controller reduces software computational load via main processor and simplifies hardware strictures by the time-division control. The device is integrated with existing dynamic simulation algorithms running separate workstation, so that objects can be manipulated in real time and the corresponding forces felt back by the operator.

• 한국해양공학회지
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• 제14권3호
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• pp.20-28
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• 2000

Using the hydraulic and numerical model of semi-enclosed bay (Chinhae Bay), the efficiencies of flow-control structures on the seawater-circulation in the inner bay were investigated. Expecially, this study was confirmed the effectiveness of the flow-control structures at the mouth and narrow channel of Chinhae Bay through the experiments. The system of flow-control structures could enhance the water exchange improvement appropriately. The results of this study can be used as the long-term and integrated environmental impact assessment model in the inner bay.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2000년도 춘계종합학술대회
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• pp.438-441
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• 2000

본 논문에서는 Shannon's Limit 보다 근접한 성능을 나타낼 수 있는 Turbo 부호의 기본 이론과 MAP, Log-MAP 복호알고리즘을 정리하고, 이를 바탕으로 VHDL(Very high speed integrated circuit Hardware Description Language)를 이용하여 Log-MAP Turbo 복호기를 ALTERA 사의 FLEX10k100 CPLD(Complex Programmable Logic Device)에 구현하였다.

• 한국정보통신학회논문지
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• 제1권1호
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• pp.105-111
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• 1997

This Paper Proposes a new efficient system design strategies for the acoustic-based underwater multiple modem and media access control protocol. The system aims to establish the acoustic-based communication network of an underwater vehicles for deep sea mining, which ensures a certain level of maximum throughput regardless of the propagation delay of acoustic and allows fast data transmission through the acoustic-based multiple channel. A media access control protocol for integrated communication network and it's acoustic-based communication modems that allows 'peer-to-peer' communication between a surface mining plant multiple underwater system is designed, and the proposed media access control protocol is implemented for its verification. Furthermore, a proposed design strategies which make it possible to control the multiple vehicle for an underwater mining is presented in this paper.

• ETRI Journal
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• 제29권4호
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• pp.452-456
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• 2007

Very compact 4-channel 200-GHz-spacing external cavity lasers (ECLs) were fabricated by hybrid integration of reflection gratings and superluminescent laser diodes on a planar lightwave circuit chip. The fifth-order gratings as reflection gratings were formed using a conventional contact-mask photo-lithography process to achieve low-cost fabrication. The lasing wavelength of the fabricated ECLs matched the ITU grid with an accuracy of ${\pm}0.1$ nm, and optical powers were more than 0.4 mW at the injection current of 80 mA for all channels. The ECLs showed single mode operations with more than 30 dB side lobe suppression.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 I
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• pp.569-572
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• 2003

The broadband wireless access industry, which provides high-tate network connections to stationary sites, has matured to the point at which it now has a standard for second-generation wireless metropolitan area networks. IEEE Standard 802.16, with its WirelessMAN air interface, set the stage for widespread and effective deployments worldwide. This paper presents an implementation of media access control that can be applied to BWA (Broadband Wireless Access) system. Medium access control (MAC) is a key issue in multi-access networks where a common channel is shared by many users. The designed MAC prototype roughly consists of MAC Hardware and MAC Software. The MAC Hardware part includes timing process, MAC transmission control, MAC reception control, and CRC/HCS process. The MAC Software part includes control of MAC signaling, network interface, and Physical (PHY) control. The designed MAC protocol will be integrated with the PHY of BWA in future and we can test overall system performance of MAC and PHY.

• ETRI Journal
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• 제10권2호
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• pp.3-12
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• 1988

Several ISDN (Integrated Services Digital Network) protocols have implemented at ETRI (Electronics and Telecommunications Research Institute) in an experimental network so that functional characteristics of the protocols under test could be certified against their protocol specifications with the help of the ETRI protocol test facilities. This paper describes ETRI protocol test architecture and its application to testing the NSP (Network Service Part) protocols : MTP (Message Transfer Part) level 3 and SCCP (Signalling Connection Control Part) of the CCITT CCS (Common Channel Signalling ) system No. 7 The test architecture presented here allows tests for two different protocol classes : peer-to-peer and multipeer protocolos. Some extensions are made to the conventional test architectures, namely the test coordination, test result transfer and network state observation method.

• 전기전자학회논문지
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• 제18권4호
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• pp.502-508
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• 2014

This paper has reviewed the performances of various AGCs which can be adopted in IEEE802.11p modems. IEEE802.11p, a high speed mobile communication standard for vehicles, requires high performance signal detector since the channel impulse responses are varied rapidly in time. In order to select the optimal signal detector, we simulated the performances of three detection methods. One is using RSSI signal, the other is using RSSI signal and I/Q signal, and the third is using I/Q signal through the Monte Carlo simulation. We evaluated the performances of the algorithms using our own system based on MAX 2829 transceiver(MAXIM $Integrated^{TM}$) in a real vehicular environment. As a result, the experiment using Fully I/Q signal derives the most excellent performance with the lowest minimum receiver sensitivity, packet error rate (PER) and false alarm rate (FAR).