• Advances in robotics research
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• v.2 no.2
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• pp.141-149
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• 2018

In image processing and robotic applications, two-dimensional (2D) black and white patterned planar markers are widely used. However, these markers are not detectable in low visibility environment and they are not changeable. This research proposes an active and adaptive marker node, which displays 2D marker patterns using light emitting diode (LED) arrays for easier recognition in the foggy or turbid underwater environments. Because each node is made to blink at a different frequency, active LED marker nodes were distinguishable from each other from a long distance without increasing the size of the marker. We expect that the proposed system can be used in various harsh conditions where the conventional marker systems are not applicable because of low visibility issues. The proposed system is still compatible with the conventional marker as the displayed patterns are identical.

• Proceedings of the KIEE Conference
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• 2006.04b
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• pp.251-253
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• 2006

Speed and torque controls of permanent magnet synchronous motors are usually attained by the application of position and speed sensors. However, speed and position sensors require the additional mounting space, reduce the reliability in harsh environments and increase the cost of a motor. Therefore, many studies have been performed for the elimination of speed and position sensors. This paper investigates a novel sensorless control of a permanent magnet synchronous motor. The proposed control strategy utilizes the active and reactive torque control for maximizing the active torque of a sensorless PMSM. The proposed algorithm is verified through the simulation and experimentation.

• Proceedings of the KIEE Conference
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• 2008.04c
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• pp.134-136
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• 2008

In recent years, the switched reluctance motor have been used many industrial application because of its cost advantage. SRM drivers are accomplished by switching the phase currents on and off synchronously with the rotor position which is fed back to the controller by position may deteriorate in harsh environments and increase the size and cost of the SRM drive system. This paper proposes a position sensorless method that is based on impressed pulse voltage using impressed at unenergised phases to estimate the rotor position. The current value by impressed pulse voltage compare with the threshold value. The rotor position can be estimated by observing the current value. Finally, simulation results compare with the sensor type SRM and confirm the proposed method to be useful.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.3
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• pp.124-130
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• 1999

Speed and position sensors require the additional mounting space, reduce the reliability in harsh environments and increase the cost of motor. Various control algorithms have been proposed for the elimination of speed senor. This paper investigates a novel speed sensorless control of induction motor. The proposed control strategy is based on MRAS(Model Reference Adaptive System) using state observer as a reference model for flux estimation. This algorithm may overcome several shortages of conventional MRAS: integrator problems, small EMF at low speed and relatively large sensitivity to resistance variation. The proposed algorithm is verified through simulation and experiment.

• Journal of Sensor Science and Technology
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• v.13 no.4
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• pp.264-269
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• 2004

This paper describes on an advanced technology of 3C-SiC/Si(100) wafer direct bonding using PECVD oxide to intermediate layer for SiCOI(SiC-on-Insulator) structure because it has an attractive characteristics such as a lower thermal stress, deposition temperature, more quick deposition rate and higher bonding strength than common used poly-Si and thermal oxide. The PECVD oxide was characterized by ATR-FTIR. The bonding strength with variation of HF pre treatment condition was measured by tensile strength measurement system. After etch-back using TMAH solution, roughness of 3CSiC surface crystallinity and bonded interface was measured and analyzed by AFM, XRD, and SEM respectively.

• Proceedings of the KIEE Conference
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• 2006.10d
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• pp.160-162
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• 2006

Speed and torque controls of induction motors are usually attained by the application of position and speed sensors. However, speed and position sensors require the additional mounting space, reduce the reliability in harsh environments and increase the cost of a motor. Therefore, many studies have been performed for the elimination of speed and position sensors. This paper investigates an improved sensorless control of an induction motor. The proposed control strategy utilizes the reactive power for estimating the speed of a sensorless induction motor. The proposed algorithm is verified through the simulation and experimentation.

• Proceedings of the KIEE Conference
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• 2007.04c
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• pp.71-73
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• 2007

Speed and torque controls of induction motors are usually attained by the application of position and speed sensors. However, speed and position sensors require the additional mounting space, reduce the reliability in harsh environments and increase the cost of a motor. Therefore, many studies have been performed for the elimination of speed and position sensors. This paper investigates an improved sensorless control of an induction motor. The proposed control strategy utilizes the MRAS(Model Reference Adaptive System) for estimating the speed of a sensorless induction motor. The proposed algorithm is verified through the simulation and experimentation.

• Journal of the Korean Society of Safety
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• v.23 no.4
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• pp.59-66
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• 2008

Recently, the deterioration of reinforced concrete structures, primarily due to corrosion of steel reinforcement, has become a major concern. Chloride-induced deterioration is the most important deterioration phenomenon in reinforced concrete structures in harsh environments. For the realistic prediction of chloride penetration into concrete, a mathematical model was developed in which the effects of diffusion, chloride binding and convection due to water movement can be taken into account. The aim of this research was to reach a better understanding on the physical mechanisms underlying the deterioration process of reinforced concrete associated with chloride-induced corrosion and to propose a reliable method for estimating these effects. Chloride concentrations coming from de-icing salts are significantly influenced by the exposure conditions such as salt usage, ambient temperature and repeated wet-dry cycles.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.4
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• pp.134-140
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• 1998

The authors have shown that the performance of discrete-time observer-based monitoring systems can be represented by the performance index k$_2$(P) (condition number of the eigensystem P of the observer matrix in terms of L$_2$ norm). The observers with the minimized performance index can be defined as robust observers in the sense that the observer performance can be guaranteed in harsh environments. In this paper, based on the performance index, a design methodology for the robust discrete-time observer is developed. Similar to the continuous-time case, the methodology determines the structure and eigenvalues of the observer matrix simultaneously. A complete design procedure is given for single-output case and is illustrated with a spindle-driver example. The simulation results demonstrate the improved performance compared with a traditional pole-placement observer technique.

• Journal of information and communication convergence engineering
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• v.15 no.2
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• pp.117-122
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• 2017

Three-dimensional integrated circuits (3D ICs), starting with memory cubes, have entered the mainstream recently. The benefits many predicted in the past are indeed delivered, including higher memory bandwidth, smaller form factor, and lower energy. However, 3D ICs have yet to find their deployment in aerospace applications. In this paper we first present key design tools and methodologies for high performance, low power, and reliable 3D ICs that mainly target terrestrial applications. Next, we discuss research needs to extend their capabilities to ensure reliable operations under the harsh space environments. We first present a design methodology that performs fine-grained partitioning of functional modules in 3D ICs for power reduction. Next, we discuss our multi-physics reliability analysis tool that identifies thermal and mechanical reliability trouble spots in the given 3D IC layouts. Our tools will help aerospace electronics designers to improve the reliability of these 3D IC components while not degrading their energy benefits.