• ETRI Journal
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• v.29 no.4
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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.

• Journal of the Optical Society of Korea
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• v.10 no.1
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• pp.33-36
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• 2006

This paper describes an efficient optimal design method for an arrayed waveguide grating (AWG) with flattened transfer function. The objective function is the norm of the difference between calculated and target spectra. To analyze the AWG transfer function, the Fresnel-Kirchhof diffraction formula was employed and the design variable was optical path difference of each array waveguide. The (1+1) Evolution Strategy was applied to an eight-channel coarse wavelength division multiplexing (CWDM) AWG as the optimization tool. The optimized transfer function will considerably improve the system performance.

• Management & Information Systems Review
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• v.11
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• pp.45-69
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• 2002

One of important technology that must improve compulsorily on information-oriented society stores, search and transmit cultural contents data of great quantity in heterogeneous environment. SAN appeared by solution to resolve the problem such as integration management of heterogeneous system data, effective practical use of storage, data transmission limit is happened from here. SAN is system that manage and shares data of large quantity efficiently attaching directly to high speed network such as Fiber Channel that storage system has been attached to server individually SAN became more complicated than existent storage environment although offer much advantage such as decrease of storage expense and flexibility of system configuration. This study argues management way could consider in such environment that understand complexity and component of networked storage system.

• Journal of Information Display
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• v.6 no.4
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• pp.6-10
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• 2005

The dependence of hysteresis characteristics in low temperature poly-Si (LTPS) thin film transistors (TFTs) on the gate-source voltage (Vgs) or the drain-source voltage (Vds) bias is investigated and discussed. The hysteresis levels in both p-type and n-type LTPS TFTs are independent of Vds bias but increase as the sweep range of Vgs increases. It has been found that the hysteresis in both p-type and n-type LTPS TFTs originated from charge trapping and de-trapping in the channel region rather than at the source/drain edges.

• Electronics and Telecommunications Trends
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• v.39 no.1
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• pp.25-35
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• 2024

Wireless communication, including mobile networks and local area networks, has become an essential service in the society. Wireless communication is evolving to include sensing services, as demonstrated by the increasing attention in organizations and standards such as 3GPP and IEEE 802.11. This survey presents technology trends in the integration of sensing and communication. The standardization status along with use cases provided by standards are explained. In addition, core and supporting technologies such as channel modeling, waveform design, and artificial intelligence are analyzed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.4
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• pp.793-798
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• 2012

In this paper, dependence of subthreshold current has been analyzed for doping distribution and channel structure of double gate(DG) MOSFET. The charge distribution of Gaussian function validated in previous researches has been used to obtain potential distribution in Poisson equation. Since DGMOSFETs have reduced short channel effects with improvement of current controllability by gate voltages, subthreshold characteristics have been enhanced. The control of current in subthreshold region is very important factor related with power consumption for ultra large scaled integration. The deviation of threshold voltage has been qualitatively analyzed using the changes of subthreshold current for gate voltages. Subthreshold current has been influenced by doping distribution and channel dimension. In this study, the influence of channel length and thickness on current has been analyzed according to intensity and distribution of doping.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.11a
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• pp.199-203
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• 1999

This paper is on the DSP system design and implementation for real time MPEG-2 AAC multichannel audio, and MPEG-4 object oriented audio coding. This DSP system employs two DSPs of the state of the art TMS320C6701, developed by TI semiconductor. DSP board has PCI interface for downloading application program and control the system. DSP board was designed to use for both encoder and decoder, by setting several switches. The system contains external input and output box also, for A/D and D/A conversion for eight channel audio. The input box converts multi channel digital audio to ADI format, that provides serial interface for eight channel digital audio. And the output box converts ADI format signal to multi channel audio. Through this ADI interface, DSP boards can be connected to input, output box. Implemented DSP system was tested for integration with MPEG-2 AAC encoder and decoder S/W. Currently the DSP system performs realtime AAC 4-channel audio encoding with two DSPs, and 8-channel decoding with one DSP.

• Korean Journal of Optics and Photonics
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• v.18 no.3
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• pp.185-189
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• 2007

A novel technology for CWDM (Coarse Wavelength Division Multiplexer) utilizing a PLC (Planar Lightwave Circuit)-AWG (Arrayed Waveguide Grating) fabrication process is proposed. BPM (Beam Propagation Method) Simulation results on the employed parabolic-horn-type input slab waveguide of AWG and the performance of the 20 nm-channel spacing CWDM with flattened passband are presented. Waveguides of $0.75{\triangle}%$ have been used in this experiment and the insertion loss at the peak wavelength is 3.5 dB for a Gaussian spectrum and is 4.8 dB for a flat-top spectrum. The bandwidth at 3 dB is better than 10 nm and 13 nm for Gaussian and flat-top spectra, respectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.10
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• pp.960-965
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• 2006

This research aims to develop the multiple channel electrochemical DNA chip using microfabrication technology. At first, we fabricated a high integration type DNA chip array by lithography technology. Several probe DNAs consisting of thiol group at their 5-end were immobilized on the gold electrodes. Then target DNAs were hybridized and reacted. Cyclic voltammetry showed a difference between target DNA and control DNA in the anodic peak current values. Therefore, it is able to detect a plural genes electrochemically after immobilization of a plural probe DNA and hybridization of non-labeling target DNA on the electrodes simultaneously. It suggested that this DNA chip could recognize the sequence specific genes.

• Journal of Mechanical Science and Technology
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• v.18 no.4
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• pp.597-605
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• 2004

Turbulent temperature field in a channel subject to strong wall injection has been investigated via direct numerical simulation technique. These flows are pertinent to internal flows inside hybrid rocket motors. A simplified model problem where a regression process at the propellant surface is idealized by wall injection has been investigated to understand how the temperature field is modified. The effect of strong wall injection displaces thermal boundary layer away from the wall and this causes a sharp drop of friction temperature. Turbulent diffusivity and dissipation time scale for temperature field are found to show large variations in the streamwise direction under application of wall blowing. It is, thus, expected that more sophisticated turbulence models would be required to predict the disturbed temperature field accurately.