• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.752-755
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• 2009

Recently, the production process system is largely composed automatic system using the wired network. The production process system using wired network has disadvantages that take place expense when the installed and inspected production of equipment was replaced. The each equipment happens to repair cost for control and management in production processes. In this paper, the industrial equipment that applied for IEEE 802.15.4(ZigBee) technology solves a complicated space at the plant. And then when the industrial equipments replace wired network with wireless network, this paper studied its user interface.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.2
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• pp.149-156
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• 2011

This paper reveals a distance estimation algorithm based on multi-code ultrasonic and wireless sensor network. For measuring the distances among the sensor nodes, each ultrasonic transmitter transmits multi-code ultrasonic signal simultaneously. Receivers use cross correlation method to separate the coded signals. The information of measured distances is broadcasted to each sensor node by wireless sensor network. The wireless sensor network measures the distance among the sensor nodes using the received signal strength of the broadcasting. The multi-code ultrasonic have a limitation of measurable distance. And the received signal strength is affected from an environment. This paper measures a distance using ultrasonic and a received signal strength in short range. These measured data are applied to the least square estimation algorithm. By the expansion of the fitting curve, a distance measurement in long range using the received signal strength is compensated. The coupled system reduce the error to an acceptable level.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.3
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• pp.248-253
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• 2008

This paper presents a sensing system for smart home which can detect an location transition events such as entrance/exit of a member and identify the user in a group at the same time. The proposed system is compose of two sub-systems; a wireless sensor network system and a database server system. The wireless sensing system is designed as a star network where each of sensing modules with ultrasonic sensors and a Bluetooth RF module connect to a central receiver called Bluetooth access point. We propose a method to discriminate a user by measuring the height of the user. The differences in the height of users is a key feature for discrimination. At the same time, the each sensing module can recognize whether the user goes into or out a room by using two ultrasonic sensors. The server subsystem is a sort of data logging system which read the detected event from the access point and then write it into a database system. The database system could provide the location transition information to wide range of context-aware applications for smart home easily and conveniently. We evaluate the developed method with experiments for three subjects in a family with the installation of the developed system into a real house.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.8
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• pp.699-705
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• 2012

In this paper, an infrastructure-based localization method using underwater wireless sensor network (UWSN) is addressed. A localization using the UWSN is necessary to widen the usage of underwater applications, however it is very difficult to establish the UWSN due to the restrictions of water. In this paper, to extend the usage of UWSN at the infrastructure, we propose a sophisticated UWSN localization method using the Received Signal Strength Indicator (RSSI) of the electromagnetic waves. During the electromagnetic waves propagating in underwater, there arises a lot of attenuation according to the distance, while the attenuation shows uniformity according to the distance. Using this characteristics, the localization system in underwater infrastructure is proposed and the experimental results show the effectiveness.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.7
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• pp.720-729
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• 2011

The demand for wireless technology in home automation systems has recently been increasing due to several advantages such as installation cost reduction, easy placement, easy extension, aesthetic benefits, and mobile device connectivity. Among the many wireless technologies, ZigBee is one of the most useful for home automation; a wireless home networking system can be configured using ZigBee alone. Compatibility with conventional home networking systems that are based on wired media, however, is not supported. KNX is a mature protocol for wired media that is recognized as an international standard. This paper proposes a KNX-ZigBee gateway to interface between KNX and ZigBee systems and thereby enable integration of wired and wireless home automation systems.

• Journal of the Speleological Society of Korea
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• no.81
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• pp.43-46
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• 2007

In this paper, we implement a wireless robot in which the RF communication the dangerous place where human cannot approach. In the proposed network image control system, the noise occurred in wireless communication is reduced by implementing the noise eliminating circuit and the driving time of a wireless robot is increased by adopting the recharge battery. By constructing the wireless communication, controled in the remote site with a wireless robot.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.12A
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• pp.975-983
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• 2011

In this paper, we investigate how the IEEE 802.16 based wireless system can adopt the network coding. To avoid the problem of overhearing, we focus on the bidirectional traffic, where each end node exchanges network coded data over a relay node. The bidirectional traffic is usually observed in Internet, where TCP makes congestion control and error recovery based on the acknowledgement from the opposite direction. Thus, enhancing the spectral efficiency of wireless Internet through the network coding is expected. Our simulation with realistic radio characteristics and TCP-like traffic shows that the network coding improves the throughput by an average of 36 percent compared to the simple relay case.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.8 no.4
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• pp.216-222
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• 2009

This paper proposes an integrated mobile sink networks management system which can monitor and control various kinds of wireless lan access points, located in many different areas divided by their managing groups, from multi-vendors, and their operations in networks. The proposed system has the center-local interoperability structure cooperating with local-center servers which can perform the same operations as the central servers for wireless lan access points from multi-vendors and wireless lan centric management features. For this purpose, we propose a new way of data design, messaging policy, and hierarchical system structure such that we can achieve stable and consistent management methods for various wireless access points on distributed networks.

• Proceedings of the KIEE Conference
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• 2002.11c
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• pp.31-34
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• 2002

There are two kinds of network architectures in the IEEE 802.11:[1] distributed (ad-hoc) or centralized (infrastructure) wireless network. Centralized networks have an access point (base station) that can control the wireless medium access of stations in these networks. The 802.11 MAC protocol of an access point is the same as those of other stations in the contention period. This paper propose a novel MAC protocol of an access point to solve these problems. This MAC protocol adds a new contention-free period called EPCF (Extended PCF) to resolve accumulated data in the queue of an access point. Simulation results show that the new protocol performs better throughput than the 802.11 standard MAC with the less queue memory site requirement.

• Journal of Communications and Networks
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• v.8 no.3
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• pp.297-305
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• 2006

High-rate wireless personal area network (HR-WPAN) has been standardized by the IEEE 802.15.3 task group (TG). To support multimedia services, the IEEE 802.15.3 TG adopts a time-slotted medium access control (MAC) protocol controlled by a central device. In the time division multiple access (TDMA)-based wireless packet networks, the packet scheduling algorithm plays a key role in quality of service (QoS) provisioning for multimedia services. In this paper, we propose an adaptive cross-layer packet scheduling method for the TDMA-based HR-WPAN. Physical channel conditions, MAC protocol, link layer status, random traffic arrival, and QoS requirement are taken into consideration by the proposed packet scheduling method. Performance evaluations are carried out through extensive simulations and significant performance enhancements are observed. Furthermore, the performance of the proposed scheme remains stable regardless of the variable system parameters such as the number of devices (DEVs) and delay bound.