• Proceedings of the Korean Institute of Communication Sciences Conference
• /
• 1986.04a
• /
• pp.66-70
• /
• 1986

• The Journal of the Acoustical Society of Korea
• /
• v.22 no.4
• /
• pp.276-285
• /
• 2003

In this paper, we present real-time implementation of a R2MFC/DTMF (R2 Multi Frequency Combinations/Dual Tone Multiple Frequency) tone receiver/sender using a high performance DSP (Digital Signal Processor) and apply it to a carrier class VoIP (Voice over Internet Protocol) gateway system. The Receiver utilizes the Goertzel filter and the sender adopts the harmonic resonant filter. We describe, in detail, the techniques of multi-channel real-time implementation on a Texas Instruments TMS320C62x DSP such as effective PCM (Pulse Code Modulation) in/out by means of DMA (Direct Memory Access) and McBSP (Multi Channel Buffered Serial Port) and message communication via HPI (Host Port Interface), etc. From experimental results, we confirmed that the optimized code provided 780 channel capacity at 250㎒ C6202, and the our R2MFC/DTMF receiver/sender met ITU-T (International Telecommunication Union-Telecommunication) specifications.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.7 no.5
• /
• pp.1-12
• /
• 2008

In this paper, we described about core technologies required for the seamless service implementation and the communication system structure conceiving required for call & response services in order that the real-time traffic information service is consecutively provided to the vehicle moving at high speed. The SMART highway service is the information communication environment build-up concept which the real-time C&R service is comprised of the vehicle moving with 160km/h above. It was possible in case of being the low speed car in the DSRC system structure. However, there is a limit in the high speed environment as the DSRC system like a convention. In this paper, we proposed the structure of fitting for the SMART highway environment using the hand-over technique compositing the base station and several repeaters of DSRC system.

• Journal of Communications and Networks
• /
• v.14 no.6
• /
• pp.692-702
• /
• 2012

Supporting quality of service (QoS) guarantees for diverse multimedia services are the primary concerns for WiMAX (IEEE 802.16) networks. A scheduling scheme that satisfies QoS requirements has become more important for wireless communications. We propose a downlink scheduling scheme called adaptive priority-based downlink scheduling (APDS) for providing QoS guarantees in IEEE 802.16 networks. APDS comprises two major components: Priority assignment and resource allocation. Different service-type connections primarily depend on their QoS requirements to adjust priority assignments and dispatch bandwidth resources dynamically. We consider both starvation avoidance and resource management. Simulation results show that our APDS methodology outperforms the representative scheduling approaches in QoS satisfaction and maintains fairness in starvation prevention.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2005.11a
• /
• pp.277-278
• /
• 2005

Admittance Spectroscopic analysis was applied to study the effect of LiF buffer layer and to model the equivalent circuit for poly(2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PPV)-based polymer light emitting diodes (PLEDs) with the LiF cathode buffer layer. The single layer device with ITO/MEH-PPV/Al structure can be modeled as a simple parallel combination of resistor and capacitor. Insertion of a LiF layer at the Al/MEH-PPV interface shifts the highest occupied molecular orbital level and the vacuum level of the MEH-PPV layer as a result the barrier height for electron injection at the Al/MEH-PPV interface is reduced. The admittance spectroscopy measurement of the devices with the LiF cathode buffer layer shows reduction in contact resistance ($R_c$), parallel resistance ($R_p$) and increment in parallel capacitance ($C_p$).

• Electronics and Telecommunications Trends
• /
• v.35 no.2
• /
• pp.38-49
• /
• 2020

In recent years, the unmanned aerial vehicle (UAV) assisted mobile free space optical (FSO) communication technique has attracted considerable attention regarding its aims to provide improved communication conditions for fixed-to-fixed FSO network and promising fronthaul and backhaul solutions for 5G+ wireless networks. This can be attributed to its outstanding advantages such as fast deployment and flexible network configuration. The UAV-assisted mobile FSO system can be used to provide cost-effective internet services in rural and remote areas and in hotspot areas that are characterized by increased data traffic. Additionally, it can be used to provide secure communication services under emergency circumstances. In this report, we review recent R&D trends in wireless network technology employing the UAV-assisted mobile FSO technique and key technologies for mobile FSO wireless networks. Furthermore, we introduce drone-based mobile FSO terminals and control systems that we have developed.

• Proceedings of the KIEE Conference
• /
• 2006.10a
• /
• pp.119-120
• /
• 2006

The impedance spectroscopy is one of the effective ways to understand the electrical properties of organic light emitting diodes. The frequency-dependant properties of small molecule based OLEDs have been studied. The equivalent circuit of single-layer device is composed of contact resistance ($R_c$), bulk resistance ($R_p$) and bulk capacitance ($C_p$). The equivalent circuit of double layer device is composed of two parallel circuits connected in series, each of which is a parallel resistor and a capacitor. We have fabricated a double layer device indium-rio-oxide (ITO, anode), N,NV -diphenyl- N,NV -bis(3-methylphenyI)-1,1V -diphenyl-4,4V-diamine (TPD, hole-transporting layer), tris-(8-hydroxyquinoline) aluminum (Alq3, emitting layer), and aluminum (AI, cathode) and two single layer devices ([TO/ Alq3/ AI, ITO/TPD/AI).

• Proceedings of the KIEE Conference
• /
• 2005.10a
• /
• pp.197-201
• /
• 2005

In this paper, an automatic welding carriage is developed by wireless communication. In the developed system, a data transmission of a automatic welding line tracking is adopted by RF communication. Additional, a welding condition of the automatic welding carriage IS displayed by microprocessor. Therefore, the developed system can overcome the restriction of an operating distance and perform an accurate transmission of the control signal.

• Journal of the Korean Graphic Arts Communication Society
• /
• v.13 no.1
• /
• pp.13-24
• /
• 1995

The color filter os made in four methods ; dyeing, printing electrodisposition and pigment dispersed method. Among technologies for color filter manufacture, pigment-dispersed and hybrid method are dominant over all others in commercial manufacture of large scale, fine resolution color filter for liquid crystal display. In this paper to investigate the possibility of the color filter manufacture for LCD by screen printing method, we synthesyzed PVA/sbQ screen emulation for high resolution, estimated image of printed fine pattern and manufactured color filter by screen printing. Results of the study are as follow and found the screen printing method os useful and valid from it. 1. Fine pattern is formed due to photocyclodomerization of -C=C- bond at 342nm, on the other hand unexposured parts are removed in water. 2. sharpness and resolution of fine pattern is improved at mesh streching angle 22.5 and 45 than 0 degree. It is expected due to resistance between inks and mesh streching angles. 3. Spectral characteristics of sample inks were R(640nm), G(535nm), B(470nm), transmittance were R(92%), G(79%), B(70%) and chromaticity coordinate values were R(0.62,0.33), G(0.32,0.59), B(0.14,0.17)

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.18 no.6
• /
• pp.43-59
• /
• 2019

The Traffic controller currently used in Korea is a switch control system that directly transfers 220V of high voltage to traffic lights one to one. This method requires a lot of cables, and there are concerns about electric shock. Accordingly, Korea Road Traffic Authority added the digital communication signal controller standard using digital communication method to the standard specification of the communication signal controller of the National Police Agency. Based on these specifications, this paper intended to develop digital communication call controllers. In addition, it was verified that even if the digital communication signal controller and analogue communication call controller were mixed, they could operate in the signal control system currently in operation.