• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.11
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• pp.1564-1570
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• 2015

This paper intends to suggest a sensing circuit of PWM voltage for a motor emulator operated in the inverter. In the emulation of the motor using a power converter, it is necessary to measure instantaneous voltage at the PWM voltage loaded from the inverter. Using a filter can generate instantaneous voltage, while it is difficult to follow the rapidly changing inverter voltage caused by the propagation delay and signal attenuation. The method of measuring the duty of PWM using FPGA can generate output voltage from the one-cycle delay of PWM, while the cost of hardware is increasing in order to acquire high precision. This paper suggests a PWM voltage sensing circuit using the analogue system that shows high precision, one-cycle delay of PWM and low-cost hardware. The PWM voltage sensing circuit works in the process of integrating input voltage for valid time by comparing levels of three-phase PWM input voltage, and produce the output value integrated at zero vector. As a result of PSIM simulation and the experiment with the produced hardware, it was verified that the suggested circuit in this paper is valid.

• Smart Structures and Systems
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• v.6 no.5_6
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• pp.731-748
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• 2010

Impact detection and health monitoring are very important tasks for civil infrastructures, such as bridges. Piezoceramic based transducers are widely researched for these tasks due to the piezoceramic material's inherent advantages of dual sensing and actuation ability, which enables the active sensing method for structural health monitoring with a network of piezoceramic transducers. Wireless sensor networks, which are easy for deployment, have great potential in health monitoring systems for large civil infrastructures to identify early-age damages. However, most commercial wireless sensor networks are general purpose and may not be optimized for a network of piezoceramic based transducers. Wireless networks of piezoceramic transducers for active sensing have special requirements, such as relatively high sampling rate (at a few-thousand Hz), incorporation of an amplifier for the piezoceramic element for actuation, and low energy consumption for actuation. In this paper, a wireless network is specially designed for piezoceramic transducers to implement impact detection and active sensing for structural health monitoring. A power efficient embedded system is designed to form the wireless sensor network that is capable of high sampling rate. A 32 bit RISC wireless microcontroller is chosen as the main processor. Detailed design of the hardware system and software system of the wireless sensor network is presented in this paper. To verify the functionality of the wireless sensor network, it is deployed on a two-story concrete frame with embedded piezoceramic transducers, and the active sensing property of piezoceramic material is used to detect the damage in the structure. Experimental results show that the wireless sensor network can effectively implement active sensing and impact detection with high sampling rate while maintaining low power consumption by performing offline data processing and minimizing wireless communication.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.3
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• pp.486-495
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• 2006

In this paper, a low-power 1Kb synchronous EEPROM is designed with flash cells for passive UHF RFID tag chips. To make a low-power EEPROM, four techniques are newly proposed. Firstly, dual power supply voltages VDD(1.5V) and VDDP(2.5V), are used. Secondly, CKE signal is used to remove switching current due to clocking of synchronous circuits. Thirdly, a low-speed but low-power sensing scheme using clocked inverters is used instead of the conventional current sensing method. Lastly, the low-voltage, VDD for the reference voltage generator is supplied by using the Voltage-up converter in write cycle. An EEPROM is fabricated with the $0.25{\mu}m$ EEPROM process. Simulation results show that power dissipations are $4.25{\mu}W$ in the read cycle and $25{\mu}W$ in the write cycle, respectively. The layout area is $646.3\times657.68{\mu}m^2$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.6-7
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• 2008

Current sensing in power semiconductors involves sensing of over-current in order to protect the device from harsh conditions. This technique is one of the most important functions in stabilizing power semiconductor device modules. The sense FET is very efficient method with low power consumption, fast sensing speed and accuracy. In this paper we have analyzed the characteristics of proposed sense FET and optimized its electrical characteristics to apply conventional 450V power MOSFET devices by numerical and simulation analysis. The proposed sense FET has the n-drift doping concentration $1.5\times10^{14}cm^{-3}$, size of $600{\mu}m^2$ with 4.5 $\Omega$, and off-state leakage current below 50 ${\mu}A$. We offer the layout of the proposed sense FET to process actually. The offerd design and optimization methods is meaningful, which the methods can be applied to the power devices having various breakdown voltages for protection.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.6 s.324
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• pp.59-68
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• 2004

Thanks to the development of microelectromechanical systems(MEMS), wireless communication technology and microsensor technology, it was Possible to manufacture a very small and low costdata acquisition node with sensing function, processing function, wireless communication function and battery. Thus sensor networks begin to be prevailed. The sensor network is a spontaneous system which sets up automatically routing paths and transmits asignificant data to the destination. Sensor nodes requires low-power operation because most of them use a battery as operating power. Sensor nodes transmit a sensing data to the destination. Moreover, they play a router. In fact, because the later consumes more energy than the former, the low-power routing is very important. Sensor networks don't have a routing standard unlike general wireless Ad-hoc networks. So This paper proposes a low-power routing method for anting to sensor networks. It is based on AODV and adapts a method to drop probably RREQ depending on remaining power. We examined it through simulations. From simulation results, we could confirm to reduce power consumption about $10-20\%$ and distribute equally power consumption among nodes.

• Proceedings of the KIPE Conference
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• 2003.07b
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• pp.681-685
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• 2003

In this paper, an sensing method of initial rotor position in Switched Reluctance Motor(SRM) at standstill is proposed. In case search coils are used as a position sensor, A search coil used in a method of detecting positions of TSRM has many advantages, which is highly efficient in low cost and maintenance free, and characterized by its function and role as a position sensor. However, the initial rotor position detection is very difficult because the search coil's EMF is not exist at a standstill. In this paper, a new sensing method of initial rotor position using squared Euclidean distance at a standstill too is suggested. The simulation and experiment for the proposed method are achieved. The validity of the proposed method is verified by experimental results.

• Journal of Ubiquitous Convergence Technology
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• v.2 no.2
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• pp.67-77
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• 2008

Representation of various types of information in an interactive virtual reality environment on mobile devices had been an attractive and valuable research in this new era. Our main focus is presenting spatial indoor location sensing information in 3D perception in mind to replace the traditional 2D floor map using handheld PDA. Designation of 3D virtual reality by Virtual Reality Modeling Language (VRML) demonstrates its powerful ability in providing lots of useful positioning information for PDA user in real-time situation. Furthermore, by interpolating portal culling algorithm would reduce the 3D graphics rendering time on low power processing PDA significantly. By fully utilizing the CC2420 chipbased sensor nodes, wireless sensor network was established to locate user position based on Received Signal Strength Indication (RSSI) signals. Implementation of RSSI-based indoor tracking method is low-cost solution. However, due to signal diffraction, shadowing and multipath fading, high accuracy of sensing information is unable to obtain even though with sophisticated indoor estimation methods. Therefore, low complexity and flexible accuracy refinement algorithm was proposed to obtain high precision indoor sensing information. User indoor position is updated synchronously in virtual reality to real physical world. Moreover, assignment of magnetic compass could provide dynamic orientation information of user current viewpoint in real-time.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.7
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• pp.1371-1378
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• 2009

We propose a low-power eFuse one-time programmable (OTP) memory cell based on a logic process. The eFuse OTP memory cell uses separate transistors optimized at program and read mode, and reduces an operation current at read mode by reducing parasitic capacitances existing at both WL and BL. Asynchronous interface, separate I/O, BL SA circuit of digital sensing method are used for a low-power and small-area eFuse OTP memory IP. It is shown by a computer simulation that operation currents at a logic power supply voltage of VDD and at I/O interface power supply voltage of VIO are 349.5${\mu}$A and 3.3${\mu}$A, respectively. The layout size of the designed eFuse OTP memory IP with Dongbu HiTek's 0.18${\mu}$m generic process is 300 ${\times}$557${\mu}m^2$.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.208-209
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• 2017

When controlling a three-phase inverter that drives AC motor, it is important to know the value of the current. In this case, shunt sensing methods are known as low cost and useful performance. However, for certain swithcing condition, immeasurable areas exist and it is necessary to reconstruct the current in the area. This paper proposes a reconstruction method using voltage injection in synchronous coordinates system at the area, and verify the validity of the method through simulation.

• Transactions on Electrical and Electronic Materials
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• v.13 no.2
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• pp.106-109
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• 2012

A low power methane gas sensor with microheater was fabricated by silicon bulk micromachining technology. In order to heat up the sensing layer to operating temperature, a platinum (Pt) micro heater was embedded in the gas sensor. The line width and gap of the microheater was 20 ${\mu}m$ and 4.5 ${\mu}m$, respectively. Zinc oxide (ZnO) nanowhisker arrays were grown on a sensor from a ZnO seed layer using a hydrothermal method. A 200 ml aqueous solution of 0.1 mol zinc nitrate hexahydrate, 0.1 mol hexamethylenetetramine, and 0.02 mol polyethylenimine was used for growing ZnO nanowhiskers. Temperature distribution of the sensor was analyzed by infrared thermal camera. The optimum temperature for highest sensitivity was found to be $250^{\circ}C$ although relatively high (64%) sensitivity was obtained even at as low a temperature as $150^{\circ}C$. The power consumption was 72 mW at $250^{\circ}C$, and only 25 mW at $150^{\circ}C$.