• TTA Journal
• /
• s.88
• /
• pp.121-127
• /
• 2003

• The Transactions of the Korea Information Processing Society
• /
• v.2 no.6
• /
• pp.879-890
• /
• 1995

This paper proposes the shuttle protocol that can gather management information from managed systems in an efficient way. In this paper, we implement the protocol and evaluate the performance by simulation. The major feature of the shuttle protocol is a chained logical connection through managed systems, and management informations to be collected are circulated among specified managed systems in circular order on a logical ring connection. The data generated by an managed system are relayed to a neighbor managed system and the system sends its data which has additional management information to received data. Finally, a manager stationman get all of data generated by every managed system. we will show the analysis of management traffic patterns using conventional polling schemes and the shuttle protocol implementation viable to TCP/IP network and improving existing polling mechansims. Additionally, it is performed to evaluate the packet processing time and its distribution of a manager system and a gateway, and the queue length of packet and bit length of gateway against conventional polling schemes by simulation using OPNRT, a simulation-dedicated package.

• Journal of Gifted/Talented Education
• /
• v.21 no.4
• /
• pp.945-959
• /
• 2011

Creativity is always important in science gifted education. There are many research results about enhancing the creativity. One of the ways of enhancing students scientific' creativity is to let them think and research like scientists so that they can follow how scientists find problems and solve them. So in this study, scientific creative elements were extracted from the Pauling's detailed examples of research process by using many documents. Abductive reasoning, paradox, changing the perspective, modeling, simplifying, converging thinking, diverging thinking, and metaphorical thinking are thinking methods that were extracted from the Pauling's research process. Repeated experiment, co-experiment, using both theories and experiments, and social obligation as a scientist are research methods. Scientific creative elements that were extracted suggest some direction that have more scientific creativity, more ability to find problems, and more ability to form theories in science education or in science gifted education.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.30 no.2A
• /
• pp.80-89
• /
• 2005

In IEEE 802.11 and 802.11e for ad hoc networks, DCF and EDCA use a contention-based protocol called CSMA/CA, which is simple to implement efficient when the system is light loaded. But the performance of CSMA/CA decreases dramatically when the system load is heavy because of increasing collisions. In PCF and HCF modes, stations are controlled by a base station by polling, no collision ever occurs. However, when the system load is light, the performance is poor because few stations have data to transfer. More important, PCF and HCF can not be used in the ad hoc networks. In this paper, we address a priority-based distributed polling mechanism (PDPM) that implements polling scheme into DCF or EDCA modes for ad hoc networks by adding a polling approach before every contention-based procedure. PDPM takes the advantages of polling mechanism that avoids most of collisions in a high load condition. At the same time, it also keeps the contention-based mechanism for a light loaded condition. PDPM provides quality of service (QoS) with fewer collisions and higher throughput compared with IEEE 802.11e.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.33 no.9
• /
• pp.113-119
• /
• 2005

The methods that are used for receiving data from attached devices under real-time preemptive multi-task operating system (OS) by general processors can be categorized as polling and interrupt driven. The technical approach to these methods may be different due to the application specific scheduling policy of the OS and the programming architecture of the flight software. It is one of the most important requirements on the development of the flight software to process the data received from satellite subsystems or components with the exact timeliness and accuracy. This paper presents the analysis of the I/O method of device related scheduling mechanism and the reliable data I/O methods between processor and devices.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.28 no.7B
• /
• pp.620-627
• /
• 2003

Ethernet passive optical networks (EPONs) are an emerging access network technology that provide a low-cost method of deploying optical access lines between a carrier's central office and customer sites. Dynamic bandwidth allocation (DBA) provides statistical multiplexing between the optical network units for efficient upstream channel utilization. To support dynamic bandwidth distribution, 1 propose an cyclic polling-based DBA algorithm for differentiated classes of service in EPONs. And, I show that an interleaved polling scheme severely decreases downstream channel capacity for user traffics when the upstream network load is low. To obtain realistic simulation results, I used synthetic traffic that exhibits the properties of self-similarity and long-range dependence I then analyzed the network performance under various loads, specifically focusing on packet delays for different classes of traffic.

• The KIPS Transactions:PartC
• /
• v.12C no.3 s.99
• /
• pp.387-394
• /
• 2005

Every MAC (Medium Access Control) sub-layers of IEEE 802.11x, including IEEE 802.11e, defines Connection-based and CF (Contention Free)-based service functions in common. In this paper, a New-CF method is proposed. In the proposed method, conventional Round Robin method, which is used as a polling method by IEEE 802.11x PCF (Point Coordination Function) or IEE 802.11e HCCA, is modified to give weights to channels with heavier traffic load and to provide those weighted channels with more services. Based on NS-2 simulations, it is verified the proposed method shows better throughput in general, particularly under unbalanced traffic load conditions.

• Korean Journal of Optics and Photonics
• /
• v.9 no.4
• /
• pp.215-220
• /
• 1998

We proposed an in situ measurement set-up and technique to measure the various electro-optic(E-O) properties of the E-O polymer. Using the proposed measurement set-up, the electro-optic effect and birefringence of unpoled side-chain E-O polymer induced by the strong dc and ac electric field were observed. The dependence of the E-O coefficients on the various poling conditions were measured with real time. To evaluate the thermal stability of the poled polymer the relaxation of the E-O effect was measured and the result was compared with well known polymer materials. The proposed measurement reduces the number of experimental steps and saves measurement time.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.27 no.12C
• /
• pp.1265-1275
• /
• 2002

In the network management system, there are two approaches; the centralized approach based on SNMP and the distributed approach based on mobile agent. Some information changes with time and the manager needs to monitor its value in real time. In such a case, the polling is generally used in SNMP because the manager can query agents periodically. However, the polling scheme needs both request and response messages for management information every time, which results in network traffic increase. In this paper, we suggest an adaptive network monitoring method to reduce the network traffic for SNMP-based network management. In the proposed strategy, each agent first decides its on monitoring period. Then, the manager collects them and approves each agent's period without modification or adjusts it based on the total traffic generated by monitoring messages. After receiving response message containing monitoring period from the manager, each agent sends management information periodically without the request of manager. To evaluate performance of the proposed method, we implemented it and compared the network traffic and monitoring quality of the proposed scheme with the general polling method.

• Proceedings of the Korean Institute of Communication Sciences Conference
• /
• 1998.06a
• /
• pp.829-832
• /
• 1998