• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.6
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• pp.183-188
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• 2014

With the rapid growth of the mobile computing and sensor technologies, various application techniques related to USN converged with other related technologies are actively disseminated recently. Most of these applications are aimed at the proper control and system monitoring using context information gathered through various sensors. But it is not easy to control and monitor the system precisely and flexibly since data generated by sensors are huge and variety. In this paper, we design and implement the fuzzy-logic based central control system in USN to provide the flexibility and preciseness with sensed data. The performance of the proposed system is evaluated by a simulation study in terms of consumed electric power on the test bed of USN based streetlight control system.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.4
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• pp.159-164
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• 2002

This paper presents the design and fabrication of a high-Tc superconducting (HTS) power supply for charging of the HTS magnet load, and its characteristics have been analyzed through experiments. HTS power supply consists of two heaters, an electromagnet, a Bi-2223 solenoid and a Bi-2223 pancake magnet load. In this experiment, 331 mH electromagnet and 0.8 A dc heater current were used, and 8.5 sec and 17 sec were used for pumping period. Mechanism of the superconducting switch is used for heater-trigger. In order to measure the pumping-current with respect to the magnet flux changes, hall sensor was installed at the center of the Bi-2223 pancake load. The experimental observations have been compared with the theoretical predictions. In this experiment, the pumping-current has reached about 1.2 A. In computer simulation, the maximum pumping-current of the system has been predicted to be about 2.7 A.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.220-221
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• 2008

With recent advanced in portable electric devices, wireless sensor, MEMS and bio-Mechanics device, the new typed power supply, not conventional battery but self-powered energy source is needed. Particularly, the system that harvests from their environments are interests for use in self powered devices. For very low powered devices, environmental energy may be enough to use power source. Therefore, in other to made piezoelectric energy harvesting device. The made 31 type triple-morph cantilever was resulted from the conditions of 100k$\Omega$, 0.25g, 154Hz respectively. The thick film was prepared at the condition of $6.57V_{rms}$, and its power was $432.31{\mu}W$ and its thickness was $50{\mu}m$.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.865-870
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• 2001

For pneumatic system control, we need a data transmission system with high speed and high reliability or information interchange between main computer and solenoid valves and I/O devices. This paper presents a set of design techniques for a data communication system that is mainly used for pneumatic system control. For this purpose, we first designed hardware modules for an interface between central control module and local node that handles the operation of solenoid valves. In addition we developed a communication protocol for construction of RS-485 based multidrop network, and this protocol is basically designed with a kind of polling technique. Finally we evaluated performance of the developed system. The field test results show that, even under high noise environment, the data transmission of 375Kbps rate is possible up to 1,000m without using repeater. In addition, the system developed in this research is proved to be used easily for extension of a communication network because of its module structure.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.6
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• pp.632-641
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• 2008

This paper is concerned with the development of the piezoelectric energy harvesting(PEH) device for ubiquitous sensor node(USN). The USN needs auxiliary power to lengthen its operational life. In this study, the piezoelectric energy harvesting system consisting of a cantilever with a tip mass and piezoelectric wafer was investigated in detail both theoretically and experimentally. The dynamic model for the addressed system was derived using the assumed mode method. The resulting equations of motion were expressed in matrix form, which had never been developed before. The power output characteristics of the PEH was then calculated and discussed. Various experiments were carried out to investigate the charging characteristics of electrical components. Theoretical and experimental results showed that the PEH was able to charge a battery with ambient vibrations but still needed an effective mechanism which can convert mechanical energy to electrical energy and an optimal electric circuit which dissipates small energy.

• Journal of Sensor Science and Technology
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• v.23 no.1
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• pp.35-41
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• 2014

Microbes have been used extensively in various fields of researches and industries but has not been used widely for microfluidic biosensor applications because it is difficult to immobilize properly to a small space. Therefore, we developed a microbial immobilization method for microfluidic devices using single-walled nanotubes and dielectrophoretic force. Single-walled nanotubes and Escherichia coli were aligned between two cantilever electrodes by a positive dielectrophoretic force resulting in a film of single-walled nanotubes with attached Escherichia coli. The optimal condition of film formation without a cell lysis was investigated. Diameter of single-walled nanotubes and electric field (intensity and duration of application) had an effect on the cell viability. On the other hand, the cell concentration of the suspension did not affect the cell viability. Paraoxon was detected using single-walled nanotubes film with attached Escherichia coli that expressed organophosphorus hydrolase. This film which is suspended from the substrate showed faster response time than sensors that are not suspended from the substrate.

• Progress in Superconductivity
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• v.13 no.3
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• pp.195-202
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• 2012

In this paper, we designed Active Magnetic Bearing (AMB) for large scale Superconductor Flywheel Energy Storage System (SFESS) and PD controller for AMB. And we experimentally evaluated SFESS including hybrid type AMB. The radial AMB was designed to provide force slew rate that was sufficient for the unbalance disturbances at the maximum operating speed. The thrust AMB is a hybrid type where a permanent magnet carries the weight of the flywheel and an electromagnetic actuator generates the dynamic control force. We evaluated the design performance of the manufactured AMB through comparison of FEM analysis and the results of experimental force measurement. In order to obtain gains of PD controller and design a notch filter, the system identification was performed through measuring frequency response including dynamics for the AMBs, a power amp and a sensor using a sine swept test method after levitating the flywheel. Through measuring the current input of the AMBs and the orbit of a flywheel according to rotational speed, we verified excellent control performance of the AMBs with small amount current for the large scale SFESS.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.4
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• pp.555-563
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• 2012

Due to the importance of energy-saving and CO2 reduction is being emphasized in the world, efforts to find a solution for the problems is increasing rapidly. In particular, the renewable energy is on understanding as a breakthrough for the protection of the environment and the economic development, so it is intensively fostered as future industries. Developed countries are already pursuing policy and technology development related with renewable energy. In this paper, we will develop MHD(Magneto Hydro Dynamics) technology to supply the commercial power that can is targeted at water pipe related with hydro power among renewable energy technologies. Kinetic energy of fluid flowing in the water pipe is converted into electric power. It allows stable power supply to the various sensors and devices on water pipe. We have performed several experiments to verify the application possibility of the developed technologies and present the result and a method of performance improvement of the technologies.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.319-322
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• 2006

The Deep-sea miner system is composed of body, actuators, sensors, and devices for control and monitoring. At present, we are manufacturing the miner's body included actuators and already consisted with off-the-shelf embedded controller. But sensors and those devices were just determined. To previously test performance of embedded controller which manages control and monitoring of miner system, its simulator must be developed for control and monitoring. Hardware-In-the-Loop(HIL) simulation is being increasingly used in industrial applications. This is an effective tool for the evaluation of electric system and drives. In the HIL simulator, we can test and design the control and monitoring system freely without the risk of hardware ruins and the load of expenses. Also the programming software for miner operating is verified on the HIL simulator. In this paper, we introduce the concept of HIL simulator for control and monitoring of deep-sea miner.

• Proceedings of the IEEK Conference
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• 2001.06a
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• pp.53-56
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• 2001

This paper has been developed a millimeter-wave radar to prevent car collision. This system needs to progress the problem as follows; (1) Increase of traffic accidents causing damage and injuries due to the increased number of motor vehicles and long distance driving, (2) Need for a device to help drivers who are in trouble due to bad weather conditions. (3) Need for a millimeter-wave radar as obstacles which need to be detected are small. This system is composited with some major technologies, Narrow beams to recognize obstacles or other objects, One-side circuit technology to prevent interference between electric waves, and Parts designed for radar products which are able to transmit millimeter - waves. The system has a various a application Field, Car distance auto-control system, prevent bump collision due to unexpected stoppage of the front car or careless driving, obstacle warning system, Car following system, and industrial and military purposes system. We have a looking forward to propose to develop field tests under various road conditions and hybrid car sensor by combining with other sensors