• 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.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.1
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• pp.10-17
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• 2013

In this paper, a new active damping method of LCL filter without capacitor voltage sensors is proposed for 3 phase PWM Inverter. Normally, L filter or LCL filter is used as an output filter of grid connected PWM inverter. An LCL filter has more excellent performance than L filter to reduce harmonic current, so the small inductance value can be used. However, the resonance problem in LCL filter is happen due to the zero impedance by the addition of LC branch. To solve the resonance problem, the various active damping method has been proposed so far. Generally, the virtual resistor active damping methods is required to additional hardware sensors for measurement of capacitor voltage and current. In this paper, the new active damping method is proposed without any capacitor voltage or current sensors. In the proposed method, the resonance component of the capacitor voltage of LCL filter can be observed by a simple MRAS(Model Reference Adaptive System) observer without additional hardware sensors, and this component is suppressed by feedforward compensation. The validity of the proposed method is proven by simulation and experiment on the 3-phase PWM inverter system.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.5
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• pp.405-410
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• 2006

We fabricated gas sensors using carbon nanotubes (CNTs) as electron emitters for the purpose of detecting inert gases. By using the silicon-glass anodic bonding and glass patterning technologies with the typical Si process, we improved the compactness of the sensors and the reliability in process. The proposed sensor, based on, an electrical discharge theory known as Paschen's law in principle, works by figuring the variation of the discharge current depending on gas concentration. In the experiment, the initial breakdown characteristics were measured for air and Ar as a function of gas pressure. As the result, even though it should be realized that there are many other factors which have an effect on the breakdown of a gap, the sensors led to similar result as predicted by Paschen's law, and they showed a possibility as gas sensors which enable to detect the gas density ranged to the vacuum pressure from 1 to $10^{-3}$ Torr.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.10
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• pp.57-62
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• 2004

We report the fiber-optic current sensors composed of a side-polished single-mode fiber with the thermo-optic Polymer layer and the metal wire as a heater. The index change of polymer layers caused by the resistant heat of the metal wires induces the optical attenuation through the evanescent field of the side-polished single-mode fiber. Two types of the sensors are proposed and their characteristics as a current sensor are investigated.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.801-803
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• 2000

The large scale magnets like thermalnuclear fusion devices are necessary for superconducting CICC cable, When the Cable In Conduit Conductors(CICC) is occurred by the external turbulence, the CICC occurs to quench, The CICC can be broken because the CICC spends all energy in the quench-happened spot. Therefore, it is necessary to develop measurement systems of the quench detection. The measurement systems of the relative good degree of efficiency are the voltage tap sensors. The weak points of voltage tap sensors are effected by EMF noise and inductance. The thermalnuclear fusion devices easily can't measure inductance value because of plasma current. In the experiment, The value of inductance was estimated by FEM techniques and the decrement of Inductance value measured as long as remaining plasma current.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.888-890
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• 2003

In the distribution networks, it is required to develop compact and smart current and voltage sensors for compact and digital switchgears. The sensor developed newly adopt the priciple of rogowski coil for current sensing and resistive voltage divider for voltage sensing. The sensing characteristics and reliabilities were improved compared to conventional ones. In the near future, these voltage and current sensing apparatus will be widely used with electronic protection units for the distribution switchgear.

• Korean Journal of Optics and Photonics
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• v.21 no.4
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• pp.168-174
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• 2010

Fiber optic current sensors based on polarization-rotated reflection interferometry are demonstrated by incorporating them into polymeric optical waveguide components, including polarization-maintaining 3-dB couplers, TE-pass waveguide polarizers, and thermooptic phase modulators. To remove the bending induced birefringence, optical fiber coil is annealed at $850^{\circ}C$ for 24 hours. The reflection interferometry comprising polymer waveguide devices exhibit a highly stable output signal corresponding to the flowing current.

• Journal of Sensor Science and Technology
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• v.17 no.5
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• pp.329-337
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• 2008

Simple, small and portable oxygen sensors were fabricated by tape casting technique. Yttria stabilized zirconia containing cordierite ceramics (YSZC) were used as a porous diffused layer of oxygen in pumping cell. Yttria stabilized zirconia (YSZ) solid electrolyte, YSZC porous diffusion layer and heater-patterned ceramic sheets were prepared by co- firing method. Limit current characteristics and the linear relationship of current to oxygen concentration were observed. Viscosity variation of the slurries both YSZ and YSZC showed a similar behavior, but micro pores in the fired sheet were increased with increasing of the cordierite amount. Molecular diffusion was dominated due to the formation of large pores in porous diffusion layer. The plateau range of limit current in porous-type oxygen sensor was narrow than the one of aperture-type oxygen sensor. However limit current curve was appeared in porous-type oxygen sensor even at the lower applied voltage. The plateau range of limit-current was widen as increasing the thickness of porous diffusion layer of the YSZ containing cordierite. Measuring temperature of $600{\sim}650^{\circ}C$ was recommended for limit-current oxygen sensor. Porous diffusion layer-type oxygen sensor showed faster response than the aperture-type one and was stable up to 30 days running without any crack at interface between the layers.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.8
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• pp.845-850
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• 2009

Localization which estimates a robot's position and orientation in a given environment is very important for mobile robot navigation. Although low-cost sensors are preferred for practical service robots, they suffer from the inaccurate and insufficient range information. This paper proposes a novel approach to increasing the success rate of low-cost sensor-based localization. In this paper, both the previous and the current data obtained from the IR sensors are used for localization in order to utilize as much environment information as possible without increasing the number of sensors. The sensor model used in the monte carlo localization (MCL) is modified so that the accumulated range information may be used to increase the accuracy in estimating the current robot pose. The experimental results show that the proposed method can robustly estimate the robot's pose in indoor environments with several similar places.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.987-992
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• 2000

In a high speed spindle system, it is very important to monitor the operation of the spindle to prevent catastrophic damage to the system. Widely used sensors for monitoring are eddy-current and capacitive types. These sensors provide high accuracy of monitoring, but their steep prices lead to expensive high speed spindle systems. The main goal of our research is to develop technology for producing high speed spindle system utilizing magnetic bearings. As active magnetic bearings require position sensors for feedback control, a noncontact position sensor is being developed as a part of this main goal. Once developed, it will contribute to affordable high speed spindle system. This paper describes the selection process of the sensor types and the design of the driving circuit. We also report the experimental results that characterize the static and dynamic performances of the inductive sensor.