• Journal of Communications and Networks
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• v.6 no.2
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• pp.123-132
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• 2004

The various challenges to realize a fixed wireless ATM network are discussed and some solutions for these challenges are presented. In this paper, the capacity allocation in wireless ATM, the wireless link impact on ATM traffic, and the optimum utilization of the wireless network resonrces for a line of sight (LOS) winless ATM link are studied. An adaptive MQAM modulator is introduced to provide a suitable solution to these issues. The modulator level is adjusted using a unique QoS metric in a wireless network. The metric, termed modified effective bandwidth, takes into account the bandwidth demand, QoS requirements, and outage conditions of the wireless ATM link. A performance study using VBR MPEG-l video traffic in a fixed wireless channel (Ricean channel) demonstrates the advantages of the proposed system.

• ETRI Journal
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• v.33 no.6
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• pp.965-968
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• 2011

A 1.485-Gbit/s video signal transmission system at carrier frequencies of 240 GHz and 300 GHz was implemented and demonstrated. The radio frequency front-ends are composed of Schottky barrier diode subharmonic mixers (SHMs), frequency triplers, and diagonal horn antennas for the transmitter and receiver. Amplitude shift keying with an intermediate frequency of 5.94 GHz was utilized as the modulation scheme. A 1.485-Gbit/s video signal with a high-definition serial digital interface format was successfully transmitted over a wireless link distance of 4.2 m and displayed on an HDTV with a transmitted average output power of 20 ${\mu}W$ at a 300-GHz system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.10
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• pp.2292-2300
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• 2015

Car rear-view camera system supplies services for safe driving and easy parking by showing the rear-view of the vehicle through a monitor when reversing the car. In this paper we researched implementation methods and technology of a Car Rear-view Camera System based on the Binary CDMA technology-new technology of wireless personal area network developed by Korea - that makes free installation without wired cables restriction and reduces installation costs. Through this research we manufactured a prototype system, and researched the implementation of camera input and monitor output modules, Binary CDMA wireless communication and application programs for wireless video transmitter and relay server.

• Journal of Korea Multimedia Society
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• v.15 no.12
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• pp.1464-1474
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• 2012

In this paper, we propose a QoS (Quality of Service)-aware and cooperative resource reservation scheme using cross-layer link adaptation for wireless high definition video transmission through UWB (Ultra Wide Band) network with D-MAC (Distributed Medium Access Control). A wireless high definition video transmission system usually requires stable high throughput even without line-of-sight, e.g., a destination device in another room separated by a wall. Since the WiMedia D-MAC supporting DRP (Distributed Reservation Protocol) scheme causes lots of DRP resource reservation conflicts due to failure of beacon detection in wireless channel environment, overall performances of the WiMedia D-MAC can be deteriorated. And the current WiMedia MAC standard has not considered QoS provisioning even though QoS parameters such as a range of service rates are provided to each traffic stream. Therefore, we propose Relay DRP protocol with QoS-based relay node selection criterion, which makes a relay path to avoid DRP resource reservation conflicts and guarantee QoS more stably through cross-layer link adaptation of cooperative relay transmission scheme and is compliant with the current WiMedia D-MAC protocol. Simulation results demonstrate performance improvements of the proposed method for throughput and QoS provisioning.

• Proceedings of the Korea Contents Association Conference
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• 2015.05a
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• pp.25-26
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• 2015

The Unattended fire detection system using a wireless communication device is designed in this paper. If a fire occurs in some area, the system can detect and automatically extinguish the fire. The major functions for the system are: Unattended detection system for fire based on wireless communication system and Automatic extinguish device system; Thermal imaging camera and video camera system; Monitoring viewer and map viewer system.

• Proceedings of the IEEK Conference
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• 2002.06c
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• pp.235-238
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• 2002

This paper presents a remote mobile robot system that transmits streaming video and audio over the lossy packet networks such as (Wireless) LAN. The error resilient video and audio packets are transmitted on the RTP/UDPfP Protocol stack. The mobile robot can be accessed by a certified user from the remoted area. Thus, the movement of mobile robot can be controlled by the operator observing the working surroundings.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.6
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• pp.989-996
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• 2008

Recently, a few types of fish-cage in open sea are researched. This fish-cage has to operate monitoring system for keeping an optimum living condition for fish. The most efficient monitoring system is WVMS(Wireless Vision Monitoring System) for fish-cage in open sea. WVMS should be able to transmit video signal and communicate with each controller. So. it needs to be based on WLAN(Wireless LAN) which has characteristic of higher transfer-rate, In this paper, we propose a structure of WVMS using WLAN equipments for maritime environment and prove its effectiveness. We present the propagation loss model of WVMS's communication channel. measured by field test, and discuss its validity compared with the predictive value based on the Friss propagation model and Plane earth reflection model. We present the number of frames that is received from WLAN modem connecting with underwater-camera in field test spots. As a result, we confirmed that proposed WVMS is suitable for maritime environment and it is possible to be applied to fish-cage in open sea on 'seogwipo'.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.3
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• pp.919-940
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• 2012

Video on Demand (VOD) is a multimedia service which allows a remote user to select and then view video at his convenience at any time he wants, which makes the VOD become an important technology for many applications. Numerous periodic VOD broadcasting protocols have been proposed to support a large number of receivers. Broadcasting is an efficient transmission scheme to provide on-demand service for very popular movies. This paper proposes a new broadcasting scheme called Popularity Cushion Staggered Broadcasting (PCSB). The proposed scheme improves the Periodic Broadcasting (PB) protocols in the latest mobile VOD system, which is called MobiVoD system. It also, reduces the maximum waiting time of the mobile node, by partitioning the $1^{st}$ segment of the whole video and storing it in the Local Media Forwarder (LMF) exactly in the Pool of RAM (PoR), and then transmitting them when the mobile nodes miss the $1^{st}$ broadcasted segment. The results show that the PCSB is more efficient and better than the all types of broadcasting and caching techniques in the MobiVoD system. Furthermore, these results exhibits that system performance is stable under high dynamics of the system and the viewer's waiting time are less than the previous system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.4
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• pp.381-388
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• 2015

In this paper, a wireless video streaming system is designed and implemented for TV white space applications. It consists of a RF transceiver module, a digital modem, a camera, and a LCD screen. A VGA resolution video is captured by a camera, modulated by modem, and transmitted by RF transceiver module, and finally displayed at a destination 2.6-inch LCD screen. The RF transceiver is based on direct-conversion architecture. Image leakage is improved by low pass filtering LO, which successfully covers the TVWS. Also, DC offset problem is solved by current steering techniques which control common mode level at DAC output node. The output power of the transmitter and the minimum sensitivity of the receiver is +10 dBm and -82 dBm, respectively. The channel bandwidth is tunable among 6, 7 and 8 MHz according to regulations and standards. Digital modem is realized in Kintex-7 FPGA. Data rate is 9 Mbps based on QPSK and 512ch OFDM. A VGA video is successfully streamed through the air by using the developed TV white-space RF communication module.

• Journal of Convergence for Information Technology
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• v.9 no.3
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• pp.30-35
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• 2019

An unattended recording system based on smartphone based image image tracking is rapidly developing. Among the existing products, a system that automatically tracks and rotates the object to be photographed using an infrared signal is very expensive for general users. Therefore, this paper proposes a mobile unattended recording system that enables automatic recording by anyone who uses a smartphone. The system consists of a commercial mobile camera, a servomotor that moves the camera from side to side, a microcontroller to control the motor, and a commercial wireless Bluetooth Earset for video audio input. In this paper, we designed a system that enables unattended recording through image tracking using smartphone.