• Proceedings of the Korean Information Science Society Conference
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• 2011.06a
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• pp.422-425
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• 2011

IPTV와 같은 멀티미디어 트래픽의 이용량이 증가함에 따라, 멀티미디어 서비스의 품질을 향상시키기 위한 스트리밍 전송 기법들이 연구되고 있다. 기존 연구들은 네트워크 상태를 고려한 스트리밍 전송으로 네트워크의 효율성과 공정성을 향상시켜 서비스 품질(QoS)을 보장하지만 사용자가 인지하는 체감 품질(QoE)을 동시에 보장하지 못하는 한계를 가지고 있다. 본 논문에서는 스트리밍 서비스의 체감 품질을 향상시키기 위해 비디오의 품질을 단계적으로 변화시키는 스트리밍 기법을 제안한다. 제안하는 기법은 수식 기반의 TCP(Transmission Control Protocol) 전송률을 기반으로 네트워크 상태를 측정하여 단계적으로 품질을 조절하고, 일정시간 동안 품질 조절의 수행을 제한한다. 이를 통해 급변하는 네트워크 상태 변화에 따른 잦은 품질 변화를 피하여 체감 품질을 향상시킨다. 실험을 통해 제안하는 기법의 유효성을 확인하였다.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06d
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• pp.222-224
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• 2012

UDT(UDP Data Transfer protocol)는 UDP 기반 전송프로토콜로써 TCP와 같은 전송 신뢰성과 안정성을 보장하면서 우수한 전송성능을 보이고 있다. 성능향상을 위해 다수의 채널을 이용하는 병렬전송 기법이 시도되고 있으나, 이는 네트워크 환경에 최적의 성능을 보이는 채널의 수의 결정이 매우 중요하다. 그러나 데이터를 전송하기 전에 매번 현재의 네트워크 환경에 최적인 채널 수를 결정하는 실험을 하는 것은 불편한 일이다. 본 논문에서는 UDT 기반 병렬전송에서 최적의 채널 수 예측기법을 제안한다. 실험을 통해 네트워크 환경에 따른 채널 수의 추이를 분석하고 최적 채널 수 결정 기법에 대해 논하고자 한다.

• Journal of Astronomy and Space Sciences
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• v.25 no.4
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• pp.347-360
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• 2008

In this paper, a Hardware-In-the-Loop simulator to simulate attitude control of space craft using momentum wheels is developed. The simulator consists of a spherical air bearing system allowing rotation and tilt in all three axes, three momentum wheels for actuation, and an AHRS (Attitude Heading Reference System). The simulator processes various types of data in PC104 and wirelessly communicates with a host PC using TCP/IP protocol. A simple low-cost momentum wheel assembly set and its drive electronics are also developed. Several experiments are performed to test the performance of the momentum wheels. For the control performance test of the simulator, a PID controller is implemented. The results of experimental demonstrations confirm the feasibility and validity of the Hardware-In-the-Loop simulator developed in the current study.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.12
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• pp.179-184
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• 2002

In this study, we developed a portable device which can monitor and analyze vibration signals from machines. This system consists a PDA loading the program for vibration analysis and A/D board for vibration acquisition. A PDA is smaller than the palm of the hand, but it has a powerful computing ability as much as an IBM compatible PC with a Pentium 100MHz CPU. The A/D board developed in this study supports LAN interface using TCP/IP communication protocol. The application program for vibration analysis includes signal processing module, fault diagnosis module, data store module, and plot display module. MS visual embedded C＋＋ 3.0 was used to developed the program.

• Proceedings of the KIEE Conference
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• 2002.07a
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• pp.22-24
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• 2002

This paper introduces the real-time soil thermal property analyzer and temperature measuring system which is combined with radio telecommunication technique. To measure the thermal parameters in real-time, the radio telecommunication technique are used the personal communication service (PCS) which is in the world-wide serviced commercially firstly by CDMA. The thermal property analyzer has an ability of measuring thermal resistivity, thermal diffusivity and thermal stability. To estimate the soil thermal properties, the curve fitting algorithm by means of the least square method are used. TCP/IP protocol and MTM are used to install the real-time soil thermal property and temperature measurement system at multiple locations along routes of the underground power cables and to reduce the cost of telecommunication.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.602-605
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• 2001

This paper focus on a method to use Ethernet Network for Industrial Communication Network. Ethernet use the CSMA/CD MAC(Medium Access Control) Protocol at the Data-Link Layer, Which isn't suit for Industrial Communication Network requiring Real-Time Communication, periodic data processing, critical data processing characteristics. In this paper we proposed the Virtual Polling Algorithm at the Application Layer will be solution of using the Ethernet Network for the Industrial Communication Network, Proposed Algorithm terminate the Collision in the network thus Delay Time is reduced and Real-Time Communication will be implemented.

• Korean Journal of Computational Design and Engineering
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• v.5 no.4
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• pp.327-335
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• 2000

The spent fuel rod extracting machine is automatically operated in high radioactive environment, so high reliability of operation is required. In this paper, to enhance the reliability of this machine by providing a close monitoring capability. a real time graphic simulation method is suggested. This method utilizes conventional IGRIP (Interactive Graphics Robot Instruction Program) 3D graphic simulation tool to visualize and simulate the 3D graphic model of this machine. Also, the dedicated protocol is defined for transmission of the operational data of the machine. The real time graphic simulation is realized by developing the socket module between a graphic workstation and a machine control computer through the TCP/IP network and by dividing the 3D graphic simulation GSL(Graphic Simulation Language) program as a small sized sub routine. The suggested method is implemented while automatically operating the rod extracting machine. The result of implementation shows that the real time 3D graphic simulation is well synchronized with the actual machine according to the operational data.

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.3
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• pp.196-203
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• 2003

Recent increase in accessibility to the internet makes it easy to use the internet-connected devices. The internet could allow any user can reach and command any device that is connected to the network. But these teleoperation systems using the internet connected device have several problems such as the network time delay, data loss and development cost of an application for the communication with each other. One feasible solution is to use local and external network line for the network time delay, transmission control protocol for data loss and Java language to reduce the development period and cost. In this study, web-based remote control system using Java language is newly proposed and implemented to a pneumatic servo control system to solve the time delay, data loss and development cost. We have conducted several experiments using pneumatic rodless cylinder through the internet and verified that the proposed remote control system was very effective.

• Proceedings of the IEEK Conference
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• 2002.06c
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• pp.37-40
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• 2002

Intelligent Wearable Module is intelligent system that arises when a human is part of the feedback loop of a computational process like a certain control system. Applied system is mobile robot. This paper represents the mobile robot control system remote controlled by Intelligent Wearable Module. So far, owing to the development of internet technologies, lots of remote control methods through internet have been proposed. To control a mobile robot through internet and guide it under unknown environment, We propose a control method activated by Intelligent Wearable Module. In a proposed system, PDA acts as a user interface to communicate with notebook as a controller of the mobile robot system using TCP/IP protocol, and the notebook controls the mobile robot system. Tlle information about the direction and velocity of the mobile robot feedbacks to the PDA and the PDA send new control method produced from the fuzzy inference engine.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.536-541
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• 2000

A low cost PC based simulator for excavator manipulation has been developed using virtual reality technology. The simulator consists of two joystick input devices, server and client PCs, an excavator kinematics module, and a graphic rendering program Open Inventor. In order to use two joysticks in the PC window environment multi-thread programing with network protocol TCP/IP has been used. To provide realistic view to the operator, CAD program Pro/Engineer and 3D modeller have been employed to create 3D part geometry of tile manipulator and virtual environmental geometries. Those geometries also have been transformed and imported to the Open Inventor. The Simulator developed is to be improved for more realistic excavator operational training.