• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.7A
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• pp.669-677
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• 2011

Superframe in IEEE 802.15.4 Standard is subdivided into an active period and an inactive period to reduce energy consumption. But communication nodes use same data transmission range in an active period, thus communication nodes spend a lot of energy to send data another nodes. In this paper, we proposed reduce energy consumption algorithm that nodes use different transmission power. Cordinator split transmission area into four group and transmit becon message to nodes. Nodes adjust transmission power according to becon message and wates lowe energy than normal nodes. We proposed energy-efficient cross layer protocol that have different PAN (Personal Area Network) by four range group.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.109-112
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• 2010

Recently, communication components prefer Bluetooth or Zigbee for PAN. However, using these makes expensive and complicated products such as audio equipments, mobile phones, PC, etc. for transmitting simple messages with low rate. In this paper, we propose wireless communication method using ultrasonic in the audio frequency limit band with speakers and microphones which are in products. We suggest transmitting and receiving methods in the audio frequency limit band for transmitting data without affecting audio signal, and implement an ultrasonic communication modem. Finally, we verify the performance of the ultrasonic communication modem by experiments in an environment with background noise.

• Proceedings of the Korea Information Processing Society Conference
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• 2008.11a
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• pp.1215-1218
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• 2008

IEEE 802.15.4 기반의 무선 센서 네트워크는 다양한 종류의 센서들로 구성된다. 이러한 센서들은 각각 다양한 주기들로 중심 노드에게 데이터를 전송하고자 한다. 슈퍼프레임마다의 주기적인 전송을 위해 IEEE 802.15.4에서는 GTS(Guaranteed Time Slot) 메커니즘을 제공한다. 하지만 하나의 센서 네트워크에서 슈퍼프레임 길이는 모두 동일하기 때문에 이보다 긴 주기를 갖는 센서들은 GTS를 할당받고도 데이터를 전송하지 않는 경우가 발생할 수 있다. 때문에 IEEE 802.15.4의 GTS 메커니즘에서는 낮은 사용 효율의 문제가 발생한다. 본 논문은 이러한 문제를 보완하고자 주기적 GTS 할당 방법(PGTS: Periodic Guaranteed Time Slot)을 제안한다. 주기적 GTS 할당 방법에서는 단말들이 GTS 요청 시 자신의 데이터 전송 주기를 PAN 코디네이터에게 보고하고, PAN 코디네이터는 이를 고려하여 단말의 주기에 따른 슈퍼프레임에서만 GTS 구간을 할당한다. 이를 통해 주기적 GTS 할당 방법은 기존 GTS 할당 방법보다 대역의 낭비를 줄여 GTS를 효율적으로 사용가능하도록 하고 더 많은 수의 단말들에게 GTS를 배정할 수 있게 한다. 본 논문에서는 시뮬레이션 결과를 통해 주기적 GTS 할당 방법이 IEEE 802.15.4의 GTS 할당 방법보다 효율적이며 더 많은 수의 단말에게 GTS를 할당할 수 있음을 확인하였다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.11 s.353
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• pp.78-84
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• 2006

This paper proposes a method to endow the mobility to the Zigbee protocol which is a short distance wireless communication technology among the standards of wireless sensor networks. The Zigbee has a low price, long life battery, simple structure and connectivity. So it is a suitable standard for the short distance wireless communication of $10m{\sim}70m$. As the Zigbee does not support the mobility, additional factors should be studied to deal adeptly with the diverse change in the real field. By solving the problem that the previous connection and binding table of the Zigbee end device should be reset due to the Zigbee end device address variation when the Zigbee end device moves from the present router to another router, this paper presents the method to communicate without data loss or disconnection.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.9
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• pp.4188-4206
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• 2016

Power control is widely used to reduce co-channel interference in wireless networks and guarantee the signal-to-interference plus noise ratio (SINR) of ongoing connections. This technique is also effective for wireless body area networks (WBANs). Although achieving satisfactory SINR is important for WBAN users, they may not be willing to achieve it at arbitrarily high power levels since power is a scarce resource in WBANs. Besides, for WBANs with different purposes, the QoS requirements and concern about the power consumption may be different. This motivates us to formulate the power control problem using the concepts from microeconomics and game theory. In this paper, the QoS objective is viewed as a utility function, which represents the degree of user satisfaction, while the power consumption is viewed as a cost function. The power control problem consequently becomes a non-cooperative multiplayer game, in which each player tries to maximize its net utility, i.e., the utility minus the cost. Within this framework, we investigate the Nash equilibrium existence and uniqueness in the game and derive the best response solution to reach the Nash equilibrium. To obtain the optimal transmission power in a distributed way, we further propose a utility-based and QoS-aware power control algorithm (UQoS-PCA). Tunable cost coefficient in UQoS-PCA enables this scheme to be flexible to satisfy diverse service requirements. Simulation results show the convergence and effectiveness of the proposed scheme as well as improvements over existing algorithm.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.9
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• pp.4186-4192
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• 2012

Because wind turbines are larger and more off-shore construction due to economic and environmental factors, it is more difficult to access the wind turbine as well as the necessary parts and the maintenance costs are increasing. So, we need to minimize fault elements and to prevent a secondary accident at failure through monitoring to reduce maintenance costs and to increase reliability of operation. In this paper we have implemented ZigBee based wireless sensor nodes and network for wind turbine condition monitoring using temperature, humidity, voltage, current, wind direction, and wind speed sensors. ZigBee wireless sensor nodes signals are transmitted to a central monitoring system via routers. Also, the sensor signals are collected and processed using LabVIEW program to monitor the wind turbine conveniently. The administrators and users can monitor the condition of wind turbine at remote site in real time over TCP/IP.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.8A
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• pp.656-663
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• 2005

This paper presents a multi-channel enhancement scheme for the MAC protocol of IEEE 802.15.3 High-rate WPAN (Wireless Personal Area Network). The current MAC protocol of the IEEE 802.15.3 High-rate WPAN is designed for sharing a single channel among DEVs of a piconet; that is, within a single piconet, PNC prevents interference through MAC layer assignment of time slots to other DEVs using time-division multiple access. When the number of DEVs that communicate with each other frequently, is increased in a single WPAN, the size of the superframe becomes inevitably large, and this may result in a significant throughput drop or a failure to provide QoS guarantee. A multi-channel enhancement scheme for the MAC protocol of IEEE 802.15.3 High-rate WPAN is proposed to significantly increase the aguegate throughput and more reliably provide the QoS guarantees in a piconet

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.8
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• pp.918-931
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• 2013

The conventional object tracking techniques using PTZ camera detects object movements by analyzing acquired image. However, this technique requires expensive hardware devices to perform a complex image processing. And it is occasionally hard to detect object movements, if an acquired image is low quality or image acquisition is impossible. In this paper, we proposes a smart security CCTV system applying to wireless sensor network technique based on IEEE 802.15.4 standard to overcome the problems of conventional object tracking technique, which enables to track suspicious objects by detecting object movements and GPS data in sensor node. This system enables an efficient control of PTZ camera to observe a wide area, decreasing image processing complexity. Also, wireless sensor network is implemented using mesh networks to increase the efficiency of installing sensor node.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.7
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• pp.1441-1449
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• 2015

Wireless universal serial bus (WUSB) is the USB technology merged with WiMedia PHY/MAC. WUSB can be applied to wireless persanal area network (WPAN) applications as well as PAN applications like wired USB. Because numerous WUSB networks operate independently for each application, data conflict can occur between adjacent networks. To avoid data conflict, the resource in a different time zone can be utilized. However, if devices in a network increase, available resources in the network decrease, and then the lack of resources necessary to provide service can occur. To solve this problem, we propose interference avoidance scheme for WUSB systems.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.6
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• pp.269-274
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• 2013

In this paper, we propose the design and implementation method of picking system using zigbee wireless communication in order to solve problems of the conventional picking system which has expensive labors and maintenance costs. We use multi router based star-tree topology as a default routing topology to provide the reliable data transmission and define the method of ID configuration and data transmission. We confirm that successful data transmission ratio of multi router based picking system is maximum 20% higher than that of single router based picking system.