• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.12
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• pp.2205-2209
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• 2007

In this paper, a voltage controlled oscillator(VCO) of core components for wireless subscriber network is designed. The type of oscillator is colpits method and the oscillator device uses a LC resonator. The product is made on FR-4 substrate with dielectric constant of 4.6. The designed VCO is operated at 3.2V, 10mA and has output value of 0.67dB. The VCO's phase noise property is -102DBc/Hz at offset frequence of 100kHz. The fabricated VCO is the same as target value and can be used for wireless subscriber network.

• Journal of the Korean Society of Industry Convergence
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• v.16 no.4
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• pp.127-132
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• 2013

We describe a research about remote control of mobile robot based on voice command in this paper. Through real-time remote control and wireless network capabilities of an unmanned remote-control experiments and Home Security / exercise with an unmanned robot, remote control and voice recognition and voice transmission are possible to transmit on a PC using a microphone to control a robot to pinpoint of the source. Speech recognition can be controlled robot by using a remote control. In this research, speech recognition speed and direction of self-driving robot were controlled by a wireless remote control in order to verify the performance of mobile robot with two drives.

• Journal of the Korea Institute of Military Science and Technology
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• v.16 no.4
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• pp.414-421
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• 2013

In this paper, a novel IFF(Identification of Friend and Foe) landmine system has been designed and fabricated using RFID(Radio Frequency Identification) wireless communication system. The IFF landmine system is composed of RECOMS(Remote Controlled Munition System), RFID reader and RFID tag. When the friendly forces have been identified by RFID wireless communication, the IFF landmine is unloaded automatically and indicates the warning message to the operator. Through the discussion, the detailed designs and the test results of identification distance have been described and antenna revision plans for improving the performance have been mentioned.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.11a
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• pp.925-928
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• 2010

Wireless sensor networks are composed of a large number of sensor nodes with limited energy resources. One critical issue in wireless sensor networks is how to gather sensed information in an energy efficient way since the energy is limited. The clustering algorithm is a technique used to reduce energy consumption. It can improve the scalability and lifetime of wireless sensor network. In this paper, we introduce a clustering protocol with mode selection (CPMS) for wireless sensor networks. Our scheme improves the performance of BCDCP (Base Station Controlled Dynamic Clustering Protocol) and BIDRP (Base Station Initiated Dynamic Routing Protocol) routing protocol. In CPMS, the base station constructs clusters and makes the head node with highest residual energy send data to base station. Furthermore, we can save the energy of head nodes using modes selection method. The simulation results show that CPMS achieves longer lifetime and more data messages transmissions than current important clustering protocol in wireless sensor networks.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.05a
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• pp.209-214
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• 2002

We developed a small, remote controlled observation ship that can reduce the cost of gathering data for marine and coastal environments. The control system is composed of three microprocessors, one is for overall mission control, another for control of propulsion motors, and the other for sensor operation. For communication system, we adopt direct and indirect methods based on the wireless modem of commercial cellular telephone. The former is a direct communication between the modems of the ship and the server, and the latter is an indirect communication via internet between the ship and the server. The performance of the ship is demonstrated with the results produced by sets of experiments.

• Smart Structures and Systems
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• v.4 no.5
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• pp.531-548
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• 2008

Recently, dense sensor instrumentation for structural health monitoring has motivated the need for novel passive wireless sensors that do not require a portable power source, such as batteries. Using a layer-by-layer self-assembly process, nano-structured multifunctional carbon nanotube-based thin film sensors of controlled morphology are fabricated. Through judicious selection of polyelectrolytic constituents, specific sensing transduction mechanisms can be encoded within these homogenous thin films. In this study, the thin films are specifically designed to change electrical properties to strain and pH stimulus. Validation of wireless communications is performed using traditional magnetic coil antennas of various turns for passive RFID (radio frequency identification) applications. Preliminary experimental results shown in this study have identified characteristic frequency and bandwidth changes in tandem with varying strain and pH, respectively. Finally, ongoing research is presented on the use of gold nanocolloids and carbon nanotubes during layer-by-layer assembly to fabricate highly conductive coil antennas for wireless communications.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.243-245
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• 2005

This paper presents a wired and wireless linked remote control system. Ethernet based network communication is used for long distance management and 2.4GHz RF network is adopted for the local area communication between the main network and the ballast. For the effective remote control and management including dimming using wired and wireless linked digital communication networks, control circuit of the ballast is implemented with fully digital circuit using MCU and EPLD. In this paper, the proper frame structure is proposed for the digital-remote lighting-control system and the detailed system configurations including fully digital controlled ballast for the induction lamp are described.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.734-738
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• 2002

In this paper, a novel wireless parallel operation algorithm of N+1 redundant UPS system with no control interconnections is presented. The load sharing of multiple UPS modules are controlled by Q-V droop and $P-\delta$ droop algorithm. This algorithm compensates for inverter parameter variation and line impedance imbalances with wireless auto-tuning method. And to increase the reliability of transient characteristic under parallel operation, a virtual injected Impedance is proposed to decrease a circulation current between inverter modules. Simulation results are provided to prove the novel wireless algorithm.

• 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.

• Journal of Electrical Engineering and Technology
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• v.5 no.1
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• pp.151-155
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• 2010

Reconfigurable radio technology is needed to reconstruct frequency and modem functionality, which can be different in various regions. In addition, it makes a single mobile handset capable of supporting various standards of wireless communication and thus plays a key role in mobile convergence. An MMIC VCO (voltage controlled oscillator) has been developed for high power and wide bandwidth where Clapp-Gouriet type oscillators are adapted for series feedback, and was fabricated based on 0.15um pHEMT of TRW. The MMIC VCO was connected to an aluminar substrate on the carrier for testing. This MMIC VCO module showed good performance in comparison to existing works. Furthermore, it can be potentially extended to reconfigure an MMIC VCO for wireless systems such as military applications and satellite communications.