• Journal of Korean Society on Water Environment
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• v.21 no.2
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• pp.132-140
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• 2005

The pilot test of a new alternative for small wastewater treatment system has been conducted for two years. It consists of a hybrid bioreactor and the expert system including the process control logic, PLC system, and HMI for the process automation. In order to monitor and remote control its status, the real-time data was transferred from the on-site control center to the central station via a wireless local area network. More efficient and stable performances were observed at automatic operating mode compared with the manual. On an average, COD, SS, T-N and T-P concentrations in the effluent from the hybrid bioreactor were less than 14, 7, 12 and 0.9 mg/L, respectively. According to the result from pilot tests, the quality of treated wastewater with sand filtration was enough to be utilized again.

• Journal of Korea Society of Industrial Information Systems
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• v.19 no.1
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• pp.13-18
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• 2014

Sensor nodes are used for monitoring and collecting the environmental data via wireless sensor network. The wireless sensor network with various sensor nodes draws attention as a key technology in ubiquitous computing. Sensor nodes has very small memory capacity and limited power resource. Thus, it is essential to have energy efficient strategy for the sensor nodes. Since the sensor nodes are operating on the same frequency bands with ISM frequency bands, the interference by the devices operating on the ISM band degrades the quality of communication integrity. In this paper, the convolutional code is proposed instead of ARQ for the error control for the sensor network. The proposed convolutional code was implemented and the BER performance is measured. For the fixed transmitting powers of -19.2 dBm and -25dBm, the BER with various communication distances are measured. The packet loss rate and the retransmission rate are calculated from the measured BER. It is shown that the porposed method obtained about 9~12% and 12-19% reduction in retransmission rate for -19.2 dBm and -25 dBm respectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.7
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• pp.573-586
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• 2013

Recently, the research, utilizing bio and environment sensors in agricultural and cattle industries, are drawing attention among the various IT convergence technologies. Among such research IT convergence techniques which aim to improve the quality of cattle industry management are necessary in particular. Real-time monitoring of the cattles health condition, identification of the cause of the diseases and timely response to such epidemic based on IT convergence techniques are among them. In order to achieve the better management of cattle industry, we propose a cattles management system which based on various bio environment sensors and wireless network technologies. The system consists of wireless environmental sensor data acquisition nodes, sensor data processing nodes, the gateway and the server. The proposed system is able to actively monitor the cattle field, to respond quickly in the case of massive cattle diseases and to control the environment of the cattle fields. We believe the proposed system will demonstrate the successful application of IT technologies to an applied field such as farming industries because of real-time crisis management capability in case of epidemic and optimal management of cattle industry.

• Journal of Korea Multimedia Society
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• v.12 no.8
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• pp.1109-1119
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• 2009

WLAN(Wireless Local Area Network) standard is currently developing with increased wireless internet demand. Though existing IEEE 802.11e demonstrates that data rates exceed 54Mbps with assuring QoS(Quality of Service), wireless internet users can't be satisfied with real communication system. After IEEE 802.11e system, Study trends of IEEE 802.11n show two aspects, enhanced system throughput using aggregation among packets in MAC (Medium Access Control) layer, and better data rates adapting MIMO(Multiple-Input Multiple-Output) in PHY(Physical) layer. But, no one demonstrates IEEE 802.11n system performance results considering MAC and PHY connection. Therefore, this paper adapts MIMO in PHY layer for IEEE 802.11n system based on A-MPDU(Aggregation-MAC Protocol Data Unit) method in MAC layer considering MAC and PHY connection. SVD(Singular Value Decomposition) method with WLAN MIMO TGn Channel is used to analyze MIMO. Consequently, Simulation results show enhanced throughput and data rates compared to existing system. Also, We use Ns-2(Network Simulator-2) considering MAC and PHY connection for reality.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.2
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• pp.176-184
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• 2011

As modern megalopolises become more complex and huge, convenience and safety of citizens are main components for a welfare state. In order to make safe society, telemetrics technology, which remotely measures the information of target system using electronic devices, is an essential component. In general, telemetrics technology consists of USN (ubiquitous sensor network) based on a wireless network, smart sensor, and SoC (system on chip). In the smart sensor technology, the following two problems should be overcome. Firstly, because it is very difficult for transducer manufacturers to develop smart sensors that support all the existing network protocols, the smart sensor must be independent of the type of networking protocols. Secondly, smart sensors should be modular so that a faulty sensor element can be replaced without replacing healthy communication element. To solve these problems, this paper investigates the feasibility of an IEEE 1451 based ZigBee smart sensor system. More specifically, a smart sensor for large network coverage has been developed using ZigBee for active telemetrics.

• The KIPS Transactions:PartC
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• v.11C no.7 s.96
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• pp.905-916
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• 2004

Self-organizing hierarchical ad hoc network (SOHAN) is a new ad-hoc network architecture designed to improve the scalability properties of conventional 'flat' ad hoc networks. This network architecture consists of three tiers of ad-hoc nodes, i.e.. access points, forwarding nodes and mobile nodes. This paper presents a topology discovery and routing protocol for the self-organization of SOHAN. We propose a cross-layer path metric based on link quality and MAC delay which plays a key role in producing an optimal cluster-based hierarchical topology with high throughput capacity. The topology discovery protocol provides the basis for routing which takes place in layer 2.5 using MAC addresses. The routing protocol is based on AODV with appropriate modifications to take advantage of the hierarchical topology and interact with the discovery protocol. Simulation results are presented which show the improved performance as well as scalability properties of SOHAN in terms of through-put capacity, end-to-end delay, packet delivery ratio and control overhead.

• Journal of IKEEE
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• v.19 no.2
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• pp.133-141
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• 2015

The IMS is an architectural control framework for delivering IP multimedia services such as voice, video, audio and data, the IMS supports not only the mobile communication system but also the existing wired and wireless network based on IP. The network that is integrated by the IMS needs policy-based network management protocol for managing the limited network resources to provide efficient multimedia service. The IMS use additional device called PDF for efficient resource management, but the PDF only uses diameter which is one of the network management protocol such as SNMP and COPS. Many devices use various protocol to manage the limited network resources. There is an algorithm using a variety of protocols such as Diameter, COPS and SNMP to handle the resources management efficiently. We also analyze the performance using the proposed algorithm in the implemented IMS environment.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.11
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• pp.2113-2119
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• 2006

In this paper, we design the r-Sensor protocol for reliable data transmission in the Intelligent Home Service based on the wireless sensor network environment. The r-Sensor protocol improve the reliability of data transmission and node fairness using simple routing algorithm, congestion control, and loss recovery method that minimize the load of relay node. Reposed routing algorithm find out upstream and downstream nodes using the Network Management packet. Meanwhile, loss recovery algorithm uses the Aggregated-Nack. To apply supposed algorithm, the IHS-AMR(Intelligent Home Service - Automatic Meter Reader) and sensor node are designed and implemented in hardware. The IHS-AMR provides remote metering service and also offers home safety service by internetworking with sensor network, mobile phone network and internet.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.1
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• pp.206-215
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• 2007

Ad-Hoc network technology is a mobile internet technology of the future that will be used widely not only in Mobile Network but also in Wireless Personal Area Network (WPAN) and Ubiquitous Network For this to occur, distributed routing protocol design, loop prevention for link information reduction in overhead for control messages and route restoration algorithm must be improved or complemented. Security techniques that can guarantee safe com-munication between Ad-Hot nodes net also be provided. This study proposes and evaluates a new authentication mechanism for MANET. The mechanism segregates the roles of certification authority to keep with the dynamic mobility of nodes and handle rapid and random topological changes with minimal over-head. That is, this model is characterized by its high expandability that allows the network to perform authentication service without the influence of joining and leaving nodes. The efficiency and security of this concept was evaluated through simulation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.8
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• pp.1088-1094
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• 2021

This paper proposes a partial BMA (Broadcasting Multiple Access) network structure and D-ARP (Distributed Address Resolution Protocol) method in order to support full mesh routing function in the DAMA (Demand Assigned Multiple Access)-based MF-TDMA (Multi Frequency-Time Division Multiple Access) satellite system. The partial BMA network enables legacy router devices and routing protocols to be adopted in the satellite communication system, and decreases the amount of routing protocol overhead. In addition, we introduce the D-ARP method that help a spoke satellite node acquiring the MAC (Media Access Control) address from remote satellite nodes in none BMA satellite network. The D-ARP method provides the MAC address of remote nodes to each other nodes through the broadcasting-enabled satellite channel. And we lastly evaluate and analysis the network performance of the proposed approach.