• Journal of Sensor Science and Technology
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• v.18 no.1
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• pp.1-21
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• 2009

There have been continued effects to develop various types of chemical sensors according to the demands in many application fields such as safety, pollution, environment, medical engineering and food industries etc. In this review, the author intended to cover the general aspects of chemical sensors, including the history of the development, the classification, the sensing properties, and the types and application examples. And the future outlook of the chemical sensor technology, focusing on the advanced materials, high technology fusion, miniaturized intelligent system and ubiquitous sensor networks etc., has been described.

• Journal of information and communication convergence engineering
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• v.6 no.2
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• pp.207-212
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• 2008

There are several sensors in the liquid cargo ship. In the liquid cargo ship, we can get values from various sensors that are level sensor, temperature sensor, pressure sensor, oxygen sensor, VOCs sensor, high overfill sensor, etc. It is important to guarantee the reliability of sensors. In order to guarantee the reliability of sensors, we have to study the diagnosis of sensor fault. The technology of smart sensor is widely used. In this paper, the technology of smart sensor is applied to diagnosis of level sensor fault for liquid cargo ship. In order to diagnose sensor fault and find the sensor position, in this paper, we proposed algorithms of diagnosis of sensor fault using independent sensor diagnosis unit and self fault diagnosis using sensor modeling. Proposed methods are demonstrated by experiment and simulation. The results show that the proposed approach is useful. Proposed methods are useful to develop smart level sensor.

• Journal of Sensor Science and Technology
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• v.14 no.6
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• pp.409-414
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• 2005

For an intelligent vehicle driving which uses magnetic markers and magnetic sensors, we can get every kind of road information while moving the vehicle if we use the code that is encoded with N, S pole direction of markers. If we make it an only aim to move the vehicle, it becomes easy to control the vehicle the more we put markers close. By the way, to recognize the direction of a marker pole it is much better that the markers have no effect each other. To get road informations and move the vehicle autonomously we propose the methods of arranging magnetic sensors and algorithm of recognizing the position of the vehicle with those sensors. We verified the effectiveness of the methods with computer simulation.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.774-779
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• 1998

For the speed control of motors, the position or speed sensors are necessary to obtain the position information of the rotor. Specially, SRM(Switched Reluctance Motor) needs an accurate rotor position data because both the rotor and the stator have a salient pole structure. High functional sensors like resolver or encoder are expensive and have complex connecting lines to the controller so the pure signals are apt to be mixed with noised. In the sight of SRM drives, the high temperature, heavy dust, and the EMI surroundings reduce the reliability of speed and position sensors. Therefore, the speed and position sensorless control algorithms using observer have been accepted widely. In this paper An adaptive sliding observer is described to control the SRM without speed or position sensors. The adaptive sliding observer is set on the basis of variable structure control theory. The sliding surface is constructed by current error terms and this surface guarantees the errors converge to "zero". The stability of observer is affirmed by Lyapunov stability analysis and popov's hyper stability theory.ty theory.

• JSTS:Journal of Semiconductor Technology and Science
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• v.17 no.1
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• pp.141-146
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• 2017

In this letter, we propose the use of tunneling field effect transistors (TFET) as a biosensor that detects bio-molecules on the gate oxide. In TFET sensors, the charges of target molecules accumulated at the surface of the gate oxide bend the energy band of p-i-n structure and thus tunneling current varies with the band bending. Sensing parameters of TFET sensors such as threshold voltage ($V_t$) shift and on-current ($I_D$) change are extracted as a function of the charge variation. As a result, it is found that the performances of TFET sensors can surpass those of conventional FET (cFET) based sensors in terms of sensitivity. Furthermore, it is verified that the simultaneous sensing of two different target molecules in a TFET sensor can be performed by using the ambipolar behavior of TFET sensors. Consequently, it is revealed that two different molecules can be sensed simultaneously in a read-out circuit since the multi-sensing is carried out at equivalent current level by the ambipolar behavior.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.6
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• pp.594-602
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• 2022

Cast-resin transformers are widely installed in various electrical power systems because of their low operating cost and low influence on external environmental factors. However, when they have an internal defect during the manufacturing process or operation, a partial discharge (PD) occurs, and eventually destroys the insulation. In this paper, a Rogowski-type PD sensor was studied to replace commercial PD sensors used for the insulation diagnosis of power apparatus. The proposed PD sensor was manufactured with four different types of PCB-based winding structures, and it was analyzed in terms of the detection characteristics for standard calibration pulses and the changes of the output voltage according to the distance. The output increased linearly in accordance with the applied discharge amount. It was confirmed that the hexagon structure sensor had the highest sensitivity, because the winding cross-sectional area of the sensor was larger than others. In addition, as the distance from the defect increased, the output voltage of the sensors decreased by 7.32% on average. It was also confirmed that the attenuation rate according to the distance decreased as the input discharge amount increased. For the application of this new type sensor, PD electrode system was designed to simulate the void defect. Waveforms and PRPD patterns measured by the proposed PD sensors at DIV and 120% of DIV were the same as the results measured by MPD 600 based on IEC 60270. The proposed PD sensors can be installed on the inner wall of the transformer tank by coating its surfaces with a non-conductive material; therefore, it is possible to detect internal defects more effectively at a closer distance from the defect than the conventional sensors.

• Transactions on Electrical and Electronic Materials
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• v.9 no.2
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• pp.84-88
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• 2008

In this paper, we analyze the errors associated with electric field interference for fiber-optic voltage sensors working in a three-phase electric system. For many practical conductor arrangements, the electric filed interference may cause errors unacceptable for the accuracy requirements of the sensors. We devised a real time compensation method for the interference by introducing geometric and weight factors. We realized the method using simple electronic circuits and obtained the real time compensated outputs with errors of 1 %.

• Journal of Sensor Science and Technology
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• v.31 no.6
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• pp.397-402
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• 2022

In this short review, we explore the recent progress in metal-based gas-sensing techniques. The strong interaction between the metal films and hydrogen gas can be considered to play a considerably important role in the gas-sensing technique. The physical and chemical reactions in Pd-Pd hydride systems were studied in terms of the phase transition and lattice expansion of the metals. Two types of represented detection, electrical and optical, were introduced and discussed along with their advantages.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.52 no.3
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• pp.181-187
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• 2003

For the moving objects with environmental sensors such as object tracking moving robot with audio and video sensors, environmental information acquired from sensors keep changing according to movements of objects. In such case, due to lack of adaptability and system complexity, conventional control schemes show limitations on control performance, and therefore, sensory-motor systems, which can intuitively respond to various types of environmental information, are desirable. And also, to improve the system robustness, it is desirable to fuse more than two types of sensory information simultaneously. In this paper, based on Braitenberg's model, we propose a sensory-motor based fusion system, which can trace the moving objects adaptively to environmental changes. With the nature of direct connecting structure, sensory-motor based fusion system can control each motor simultaneously, and the neural networks are used to fuse information from various types of sensors. And also, even if the system receives noisy information from one sensor, the system still robustly works with information from other sensors which compensates the noisy information through sensor fusion. In order to examine the performance, sensory-motor based fusion model is applied to object-tracking four-foot robot equipped with audio and video sensors. The experimental results show that the sensory-motor based fusion system can tract moving objects robustly with simpler control mechanism than model-based control approaches.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.5
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• pp.219-225
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• 2003

This paper described about the acoustic wave measurement method to diagnose GIS for particles. We measured and analyzed the signals of acoustic waves with two type acoustic sensors having 125kHz and 50kHz resonant frequency respectively when the particles were bounced on the inside surfaces of GIS tanks by the electrostatic force. To use two sensors for the diagnosis of GIS, we set up the calibration method for this measurement method. We showed the output characteristics of two sensors according to the sizes and materials of particles in the experiment. As the results, the inception voltages bouncing particles depended on the materials and the extinction voltages bouncing them depended on the sizes and materials. We found out that the relationship between sizes of particles and output voltages of sensors didn't have linearity but the ratios of between peak values of two sensors depended on the materials of GIS enclosures and the sizes of particles.