• Journal of Korea Multimedia Society
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• v.10 no.3
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• pp.335-347
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• 2007

VoIP (Voice over IP) is a technology to transport video and voice traffic over IP networks such as Internet. Today, the VoIP technology is viewed as the right choice for providing voice, video, and data communication among various terminals over the next generation network. This paper discusses a multipoint VoIP implementation with end-point mixing model which can support multipoint conference without a conference bridge. The multipoint VoIP is implemented with SIP (Session Initiation Protocol), and supports STUN (Simple Traversal of UDP Through NATs) since it works in an asymmetric NAT (Network Address Translator) environment. The characteristics of this paper are as follows. It is possible that all terminals in the hierarchical conference don't receive the duplicated media information because we use the end-point mixing model with the new media processing module. And, the paper solves the problem that the hierarchical conference session should be separated into several sessions when a mixing terminal terminates the hierarchical conference session.

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.2
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• pp.179-185
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• 2014

In this paper, a quadruped walking pet robot for human-robot interaction, a robot-controller using a smart phone application program, and a home smart control system using sensor informations providing from the robot are described. The robot has 20 degree of freedom and consists of various sensors such as Kinect sensor, infrared sensor, 3 axis motion sensor, temperature/humidity sensor, gas sensor and graphic LCD module. We propose algorithms for the robot entertainment: walking algorithm of the robot, motion and voice recognition algorithm using Kinect sensor. emotional expression algorithm, smart phone application algorithm for a remote control of the robot, and home smart control algorithm for controlling home appliances. The experiments of this paper show that the proposed algorithms applied to the pet robot, smart phone, and computer are well operated.

• Journal of Korea Multimedia Society
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• v.5 no.2
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• pp.215-221
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• 2002

In high speed optical disc devices, the vibration caused by unbalanced displacement leads the focus and tracking servo systems to be unstable, and increases the data search time. In this paper, we propose a new scheme to solve the unbalanced displacement problem. The proposed method detects the unbalanced rate by differential amplifying optical power received at photo diode and converts it into an electrical signal. controlling the speed of spindle motor, according to the detected unbalanced rate, makes it possible to improve the performance of tracking and data searching tasks. Also, we analyze the dynamic characteristics of focus and tracking servo systems in high speed mode and provide the firmware and hardware architecture that the proposed method can be installed as an add-on- module in the existing system.

• Journal of Advanced Navigation Technology
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• v.18 no.6
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• pp.541-545
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• 2014

Rec. ITU-R M.1842-1 is international recommendation for VHF band communication guideline in maritime mobile service RR Appendix 18 channels. In this paper, we simulate 28.8 kbps VHF ${\pi}$/4-DQPSK digital baseband modem compatible with the recommendation, then it is designed and implemented with FPGA. Cazac sequence is used as a preamble since packet format is not defined untill now in the recommendation. Baseband modem is designed by VHDL language and implemented on NEXYS4 development platform having Atrix7 FPGA chip from Xilinx. For wireless communication test of total prototype system, ADC/DAC board is implemented and EV9730 RF module is utilized. From the experimental results, implemented FPGA modem shows spectral bandwidth of 25 kHz and successful data exchanges between tx and rx communication platform.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.320-323
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• 2008

Due to the improvement of mobile device capabilities, a demand for various contents service is increasing. But the differences from heterogeneous mobile devices force to develop contents which is dependent on a mobile. To solve this problem, adaptation course that reorganize contents by the device capability is needed. In this course, device description is described using device description language but there are some problems that is absence of device description repository and the way to get device description data. In this paper, I suggest device description acquisition module and define the interfaces to access device description repository that I designed and implemented.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.7
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• pp.629-634
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• 2016

This paper describes the implementation of a ZigBee sensor node that can be utilized as a multiband and machine to machine (M2M) communication gateway. The IEEE 802.15.4-2003 standard was used as the wireless network frequency band. Ember's Type EM357 SoC was used as the transmission and reception device to perform the communication function, and it was also used for both the main M2M gateway and the sensor node. For the implementation of the operating protocol, EmberZNet Stack 4.5.4 from the Ember Corporation was used. The measurement of the reception sensitivity in the receiving module and the actual output signal from the reference were obtained from the transmission of a packet, and the packet included the M2M gateway within the attached ZigBee sensor. The packet error rate was measured as 0% with a -98 dBm reception sensitivity at the ZigBee frequency. In addition, excellent current characteristics of the ZigBee modules were shown by the implementation of the low-power circuit.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.7
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• pp.1653-1659
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• 2013

In this paper, we propose a new ECAD software for efficiently analyzing and debugging of digital architecture implemented in Verilog HDL or VHDL codes. This software firstly elaborates HDL codes so as to extract internal architecture structure, then generates several graphical aids such as hierarchical schematics by applying placement and routing algorithm, object tree to show configuration of each module, instance tree to show hierarchical structure of instances, and SPD (Signal Propagation Diagram) to show internal interconnections. It is more important function that same objects in different views(HDL codes, object tree, instance tree, SPD, waveform etc.) can be highlighted at the starting any object. These functions are sure to improve efficiency of manual job to fix bugs or to analyze HDL codes.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.1023-1026
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• 2013

The electronic equipment which was exposed to high level pulsed radiation is damaged as Upset, Latchup, and Burnout. Those damages has come from the instantaneous photocurrent from electron-hole pairs generated in itself. Such damages appeared as losses of power in military weapon system or of blackout in aerospace equipment and eventually caused in gross loss of national. In this paper, we have implemented a RDC(Radiation detection and control module) as part of the radiation protection technology of the electronic equipment or devices from the pulsed gamma radiation. The RDC which is composed of pulsed gamma-ray detection sensor, signal processors, and pulse generator is designed to protect the important electronic circuits from the pulse radiation. To verify the functionality of the RDC, LM118s which had damaged by the pulse radiation were tested. The test results showed that the test sample applied with a RDC was worked well in spite of the irradiation of the same pulse radiation. Through the experiments we could confirm that the radiation protection technology implemented with RDC had the functionality of radiation protection to the electronic devices.

• The KIPS Transactions:PartD
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• v.12D no.1 s.97
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• pp.151-158
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• 2005

In order to use the existing map data base in the mobile phone, the dynamic creation technique of the radio map which will be able to be converted into the raster image and transmitted was proposed. We transferred the client module functions such as the coordinate conversion, data compression and decoding to server, and made driving of JAVA browser in the mobile phone which has the restricted resources possible for the dynamic creation of the radio map. We made the radio electronic map service possible without map data base for the mobile phone use only by performing the general work of the map at the sever. And we guaranteed the client waiting time less then the limit time by performing the filtering work of the map at the server also. After we input the keyword at the user interface for searching the region or facility, and verified the performance of the proposed technique by confirming that the raster electronic map usable at the mobile phone was created dynamically.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.1B
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• pp.26-38
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• 2006

To construct seamless collaborative environments, what all participants intent should be delivered, and visual elements such gesture, facial expression, and ambiance should be shared with all participants. In this paper, we propose high-quality video service to support DV(digital video) and HDV(high-definition DV) based on Access Grid(AG) which is a prevalent collaborative system. The proposed service is designed for employing versatile media tools and codecs with SDP(session description protocol) and SAP(session announcement protocol). We also design network-adaptive video transmission module to mitigate the impact of network fluctuation. This periodically monitors multicast performance and controls frame rate on sender side considering network condition. The experimental results over the test bed show that proposed service enhances quality of AG video service and provides seamless high-quality video transport by mitigating the impact of network fluctuation.