• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.704-711
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• 2003

Recently, the demands for real-time service and multimedia data are rapidly increasing. There are significant redundancies between header fields both within the same packet header and in consecutive packets belonging to the same packet stream. But there are many overheads in using the current UDP/IP protocol. Header compression is considered to enhance the transmission efficiency for small size of payload. By sending the static field information only once initially and by utilizing dependencies and predictability for other fields, the header size can be significantly reduced for most packets. This work describes an implementation for header compression of the headers of U/UDP protocols to reduce overhead on Ethernet network. Typical UDP/IP Header packets can be compressed down to 7 bytes and the header compression system is designed and implemented on the Linux environment. Using the designed Header compression system between a server and a client have the advantage of effective data throughput in network.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.5
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• pp.972-978
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• 2016

MACsec is a cryptographic function that operates on Layer 2, the international standard defined in the IEEE 802.1AE. As industries such as IoT(Internet of Things) devices are receiving attention recently are connected to the network and Internet traffic is increasing rapidly, and is exposed to the risk of a variety of Internet attacks. Traditional network security technologies were often made in Layer 3, such as IPsec. However, to be increased as rapidly as the current traffic situation is complicated, and became interested in the security function of protecting the entire traffic instead of for a specific application or protocol. It appeared as these technologies is technology MACsec technology to protect all traffic in Layer 2. In this paper, we propose a Layer 2 security technology adapter MACsec MACsec a technology that allows you to simply and easily add them to the existing Layer 2 networks.

• The KIPS Transactions:PartA
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• v.14A no.5
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• pp.295-300
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• 2007

The Linux-based embedded systems such as mobile telephones. PDAs and MP3 players are widely in use. USB(Universal Serial Bus) is the interface for data communication between the computers and these peripheral devices. Some embedded systems like intelligent home networking and multimedia streaming require guaranteed QoS(Quality of Service), which is needed for real time transmission of UDP/IP messages through USB. Although USB Ethernet driver is supported by USB Gadget API in Linux, it is unable to provide the desirable QoS required by each type or small embedded systems due to the unpredictability or TCP/IP Stack in Linux. This paper proposes IP-Over-USB to improve QoS of UDP/IP message transmission in the embedded systems using USB in Linux system.

• The KIPS Transactions:PartC
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• v.16C no.4
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• pp.477-486
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• 2009

This paper proposes a dynamic bandwidth allocation (DBA) algorithm with adaptive maximum transmission window (DBA-AMTW) to increase channel utilization in Ethernet passive optical networks (EPONs). A polling mechanism in EPON determines channel utilization and puts constraints on DBA algorithm and scheduling. DBA algorithms based on interleaved polling with stop (IPS) allocate transmission windows to optical network units (ONU) considering requests of all ONUs. However channel idle time when any ONU does not transmit packets decreases channel utilization. Proposed DBA-AMTW improves efficiency of a network and allocates transmission windows effectively by appropriate DBA computation from REPORT messages of all ONUs. An adaptive maximum transmission window for each ONU determined by a DBA computation in the previous scheduling cycle. Simulation results show that the proposed DBA algorithm improves performance of throughput and average delay time.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1658_1659
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• 2009

PLS(Pohang Light Source) will begin the PLS-II project that has been funded by the KOREA Government in order to further upgrade the PLS which has operated since 1992. The control system of the PLS-II has distributed control architecture, with two layers of hierarchy; operator interface computer (OIC) layer and machine interface computer (MIC) layer. The OIC layer is based on SUN workstation with UNIX. A number of PC-based consoles allow to remotely operating the machine from the control room. PC-based consoles use the Linux or Windows operation system. Similar consoles in the experimental hall are used to control experiments. The MIC layer is directly interfaced to individual machine devices for low-level data acquisition and control. MIC layer is based on VMEbus standard with vxWorks real-time operating system. Executable application software modules are downloaded from host computers at the system start-up time. The MIC's and host computers are linked through Ethernet network. It should enable the use of hardware and software already developed for specific light source requirements. The core of the EPICS (Experimental Physics and Industrial Control System)[1] has been chosen as the basis for the control system software.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.7
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• pp.785-797
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• 2014

Support for the precise time synchronization of EtherCAT, known as distributed clock (DC), enables the design of highly synchronized operations in distributed real-time systems. This study evaluates the performance of the EtherCAT DC through extensive experiments in a real automation system. We constructed an EtherCAT control system using Xenomai and IgH EtherCAT stack, and analyzed the clock deviation for different devices in the network. The results of the evaluation revealed that the accuracy of the synchronized clock is affected by several factors such as the number of slave devices, period of drift compensation, and type of system time base. In particular, we found that careful decision regarding the system time base is required because it has a fundamental effect on the master operation, which results in significantly different performance characteristics.

• Journal of Biomedical Engineering Research
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• v.14 no.4
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• pp.321-326
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• 1993

Recently, microcomputer technology has been developed rapidly and it provides not only graphic user interface that can be fraendly accessable but also large storage capacity to han- dle much hospital information. Almost all the order communication system for hospital has been developed under the concept of host and terminal environment since last 20 years. However, host-terminal system has not been successful in korea simply because most of physicians prescibe for rrlany patients a day(sometimes more than 150 patients a day). Also, under the host-terminal environment, programs are not friendly implemented for users. Since March 1991, we had developed order communication system for out-patients(named YONSEI-PC) using personal computer(PC) and local area network(LAN) . Since September 1992, we has applied succesfully in the Yonsei Cardiovascular Center, Sevrance Hospital, Yonsei University College of Medicine. This system consisted with Server and Clients which is communicated through LAN(Ethernet). The system also use the Host computer(IBM 9221 170) as a data bank and communicates to the Server with emulation card(3270 emulator, Interlink Inc., Korea) . After introducing this system, it enables patients to receive drugs witllin 20 minutes after prescription of 300-400 patients per day and it seemed to be effective system not to reduce waiting time for the patients but also to remove charge-troubling(due to His-entry of prescription) . This system also seems to be effective in terms of office automatism for hospital management. However users, usually physitions, required more friendly and easy system to operate and we thought that the most important one to successfully introduce order communication computer system in the hospital is user interface.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.11 no.3
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• pp.307-312
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• 2018

In this paper, we can confirm the result of intuitive interface software implementation for operating a digital PA(Public Address) controller and the performance of audio mixer control part. Developed user interface software provides the maintaining management and control function of digital hybrid mixer. This SW loaded in the integrated control server controls an sound status of the audio mixer TAD-168M and checks the device status for Public Address integrated system. Also, this SW enables the integrated control and the continuous upgrade. Developed SW is connected to TAD-168M with Ethernet and linked to PC Lan port and the 4-port switch, located in the backside of TAD-168M, by LAN cable for communicating with operating PC. Integrated control including system management, audio control and uplink broadcasting control for broadcasting system will be made available with this novel developed system.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.6
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• pp.96-101
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• 2003

Korea Sounding Rocket(KSR)-III onboard telemetry system has acquired various data from subsystems and sensors in the rocket, and radiated PCM/FM data using two S-band antennas during the flight. Simultaneously， it is necessary that the ground receiving systems track the rocket, and receive and decode telemetry data. Also post processed telemetry data are needed to be broadcasted on ethernet network in real time. Range safety display system displays flight trajectory using telemetry data in mission control center, and so flight manager makes a decision for flight termination from the trajectory This paper describes operating technique about telemetry reception, the development for the realtime data processing system, and the results for telemetering reception on fight test. We telemetered, processed, and broadcasted numerous telemetry data during the flight test successfully.

• Journal of Advanced Navigation Technology
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• v.24 no.5
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• pp.438-443
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• 2020

To transfer files between nodes on network based on Ethernet, file transfer protocol (FTP) on TCP/IP and trivial file transfer protocol (TFTP) on UDP/IP are mostly used. Due to the lack of resources (processor, memory and so on) in the embedded system where we generally use for simple works with small firmware like ones; many of the systems implement only UDP/IP for their network stacks. Thus, TFTP is greatly to be preferred. For examples, environmental sensor devices for sensor networks, Boot Loader for general embedded device and preboot execution environment (PXE) boot for PC provide the TFTP. The logic of TFTP is simple for file transmission but, there is Stop-And-Wait problem during the process which occurs long blocking time. In this paper, we propose an algorithm which called QuTFTP(Quick UDP Trivial File Transfer Protocol) to reduce the length of the blocking time and to be compatible with the legacy TFTP.