• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.2
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• pp.290-298
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• 2008

This paper presents an efficient data storage and reconstruction method in data acquisition and processing of monitoring system. The proposed method extracts minimum data using an interpolation from raw data which are acquired from a target system. They are transferred and saved in a monitoring PC via TCP/IP communication, and then reconstructed as original signals. Therefore, it is possible to design an efficient monitoring system by the improved data communication speed due to the reduced communication packet, and it reduces the storage space. The algorithm for data acquisition and reconstruction is based on Cubic Hermite interpolation. To verify the validity of the proposed scheme, we presents simulation results compared with other interpolation based approaches. Finally, it is applied to a monitoring system for grid-connected photovoltaic power generation system to prove the high-performance of the proposed method.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.2
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• pp.173-178
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• 2019

Recently, the types and amount of data generated, collected, and measured in IoT such as smart home, security, and factory are increasing. The technologies for IoT service include sensor devices to measure desired data, embedded software to control the devices such as signal processing, wireless network protocol to transmit and receive the measured data, and big data and AI-based analysis. In this paper, we focused on developing a gateway for interfacing heterogeneous sensor network protocols that are used in various IoT devices and propose a heterogeneous network interface IoT gateway. We utilized a OpenWrt-based wireless routers and used 6LoWAN stack for IP-based communication via BLE and IEEE 802.15.4 adapters. We developed a software to convert Z-Wave and LoRa packets into IP packet using our Python-based middleware. We expect the IoT gateway to be used as an effective device for collecting IoT big data.

• International Journal of Control, Automation, and Systems
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• v.3 no.4
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• pp.591-600
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• 2005

In this paper, we discuss real-time control of networked control systems (NCSs) and practical issues in the choice of the communication networks for this purpose. An appropriate integration of control systems, real-time environments, and network communication systems allows the optimization of the quality-of-control (QoC) in NCSs. We compare several prevailing network types that may be used in control applications to offer a guideline of choosing a proper network. A real-time operating environment is also presented as an important ingredient of NCS design. To evaluate its feasibility and effectiveness, a real-time NCS containing a ball magnetic levitation (Maglev) setup is implemented via an Ethernet. Based on the experimental results, it is concluded in this paper that real-time control via Ethernet is a practical and feasible solution to NCS design.

• Journal of Communications and Networks
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• v.6 no.4
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• pp.387-396
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• 2004

One of the main problems associated with MANETs is that mobility and the associated route discovery and maintenance procedures of reactive routing protocols cause severe interruptions on real-time video streams. Some of these interruptions are too large to be concealed using any sort of video technology, resulting in communications breaks unpleasant for the final end user. We present a solution for enhanced video transmission that increases route stability by using an improved route discovery process based on the DSR routing protocol, along with traffic splitting algorithms and a preventive route discovery mechanism. We also present some video adaptative mechanisms that improve the overall performance of multipath routing in terms of video data replication and video packet splitting strategies. Combining our proposals, we achieve up to 97% less interruptions on communication with high mobility and over 1.2 dB of improvements in terms of video distortion.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.1
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• pp.103-118
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• 1996

With the advent of B-ISDN based on ATM technonlogy, ther are increasing needs for the interconnection of existing LAN/MAN's through ATM networks. ATM networks, therefore, must provide connectionless service. In this paper, the traffic distributio scheme using multi-path is proposed to support efficient connectionless service in ATM networks. Because the proposed scheme distributed the bursty traffic arrived in the interworking unit (IWU) and the connectionless server (CLS) from LAN-terminals, it alleviates the packet loss ratio caused by buffer overflow at IWU/CLS and is able to use nettowrk resources efficiently according to the network conditions and the amount of the traffic arrived at IWU/CLS. This paper presents the distribution algorithm and the IWU/CLS, CLS-CLS closed-loop rate control scheme.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.7A
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• pp.678-685
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• 2007

We implemented the network synchronization equipment for the optical transmission platform or next generation Packet/TDM(Time Division Multiplexing) data converged switching system and then, presented an impact of wander generation on the NG-SDH optical transmission network.

• Korean Journal of Human Ecology
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• v.12 no.3
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• pp.287-301
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• 2003

The purpose of this study was to explore the relationship between childrearing belief and parental efficacy of women before and after childbirth. For this purpose 253 pregnant women and 256 mothers with infants under one year of age were contacted and asked to fill in a packet of survey questionnaire at their visits to obstetrician, gynecologist and pediatrician. The questionnaire includes questions about what mothers value in childrearing, their expectations for their children and parental efficacy. Data collected were analyzed using SAS PC program. It was reported that comparing to mothers, pregnant women view childrearing in more ideal lights and expect their children to be more exceptional. Also working mothers reported comparatively lower parental efficacy than full-time mothers suggesting that social support system to minimize pressure coming from work for working mothers with young children should be provided and the parental education methods to enhance the parental efficacy should be sought.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.8
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• pp.2691-2707
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• 2014

Medium access control is critical in wireless networks for efficient spectrum utilization. In this paper, we introduce a novel collision resolution method based on the technique of known interference cancellation, and propose a new MAC protocol named as CR-MAC, in which AP tries to decode all the collided data packets by combining partial retransmissions and known interference cancellation. As the collided transmissions are fully utilized, less retransmission is required, especially in a crowded network. The NS-2simulation and MATLAB numerical results show that, under various network settings, CR-MAC performs much better than the IEEE 802.11 DCF in terms of the aggregation throughput and the expected packet delay.

• IEMEK Journal of Embedded Systems and Applications
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• v.2 no.3
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• pp.138-144
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• 2007

Wireless Sensor Network(WSN) consists of a lot of light-weight sensor nodes with the capability of wireless communication. Studies have been done to improve stability and fault-tolerancy of WSN because the sensor nodes are basically vulnerable to the harsh environment. Specially, the time synchronization among sensor nodes becomes a challenging issue in WSN. All the local times should always keep the same with each other in the sensor field to perform data aggregation and energy-aware communication in WSN. In this paper, a new time synchronization technique is proposed to operate efficiently irrespective of the number of sensor nodes and the number of hops needed to cover all sensor nodes for synchronization. Simulation results show that the proposed technique has the lowest amount of packet traffic among the several time synchronization techniques.

• ETRI Journal
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• v.29 no.2
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• pp.201-211
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• 2007

This paper focuses on the scheduling problem with the objective of maximizing system throughput, while guaranteeing long-term quality of service (QoS) constraints for non-realtime data users and short-term QoS constraints for realtime multimedia users in multiclass service high-speed uplink packet access (HSUPA) systems. After studying the feasible rate region for multiclass service HSUPA systems, we formulate this scheduling problem and propose a multi-constraints HSUPA opportunistic scheduling (MHOS) algorithm to solve this problem. The MHOS algorithm selects the optimal subset of users for transmission at each time slot to maximize system throughput, while guaranteeing the different constraints. The selection is made according to channel condition, feasible rate region, and user weights, which are adjusted by stochastic approximation algorithms to guarantee the different QoS constraints at different time scales. Simulation results show that the proposed MHOS algorithm guarantees QoS constraints, and achieves high system throughput.