• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.2
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• pp.135-140
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• 2010

This paper presents a sensorless speed control of BLDC Motor using terminal voltage of the one phase. Rotor position information is extracted by indirectly sensing the back EMF from only one of the three terminal voltages for a three-phase BLDC motor. Depending on the terminal voltage sensing rotor position, active filter is used for position information. This leads to a significant reduction in the component device of the sensorless circuit. Therefore this is a advantage for the cost saving and size reduction. With indirect sensing methods based on detection of the terminal voltage that require active filtering, the position information needs the six divider section by PLL circuit, the binary counter and johnson counter by the EPLD. Finally, this algorithm can estimate the rotor position information similar to Hall-sensor sticked the three-phase BLDC motor. As a result, the method described that it is not sensitive to filtering delays, allowing the motor to achieve a good performance over a wide speed range. In addition, a simple starting method and a speed estimation approach are also proposed. Experimental and simulation results are included to verify the proposed scheme.

• Journal of Sensor Science and Technology
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• v.10 no.3
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• pp.173-179
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• 2001

The currently used semiconductor pressure sensors are piezoresistive and capacitive type. Especially, semiconductor micro pressure sensors have a great deal of attention because of their small size. However, its fabrication processes are difficult, so that its yield is poor. For the purpose of resolving the drawbacks of the existing silicon pressure sensors, we demonstrate a new type of pressure sensor using PSFET(pressure sensitive field effect transistor) and investigate its operational characteristics. We used PZT(Pb(Zr,Ti)$O_3$) as a pressure sensing material. PZT thin films were deposited on a gate oxide of MOSFET by an rf-magnetron sputtering method. To abtain the stable phase, perovskite structure, furnace annealing technique have been employed in PbO ambient. The sensitivity of the PSFET was 0.38 mV/mmHg.

• Journal of Sensor Science and Technology
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• v.32 no.3
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• pp.199-206
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• 2023

This study presents a novel monitoring technique for underwater high-voltage direct current (HVDC) cables based on the Distributed Acoustic Sensor (DAS). The proposed technique utilizes vibration and acoustic signals generated on HVDC cables to monitor their condition and detect events such as earthquakes, shipments, tidal currents, and construction activities. To implement the monitoring system, a DAS based on phase-sensitive optical time-domain reflectometry (Φ-OTDR) system was designed, fabricated, and validated for performance. For the HVDC cable monitoring experiments, a testbed was constructed on land, mimicking the cable burial method and protective equipment used underwater. Defined various scenarios that could cause cable damage and conducted experiments accordingly. The developed DAS system achieved a maximum measurement distance of 50 km, a distance measurement interval of 2 m, and a measurement repetition rate of 1 kHz. Extensive experiments conducted on HVDC cables and protective facilities demonstrated the practical potential of the DAS system for monitoring underwater and underground areas.

• Smart Media Journal
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• v.5 no.3
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• pp.35-41
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• 2016

In this paper, we propose hand-gesture signal recognition based on EPS(Electronic Potential Sensor) using Deep learning model. Extracted signals which from Electronic field based sensor, EPS have much of the noise, so it must remove in pre-processing. After the noise are removed with filter using frequency feature, the signals are reconstructed with dimensional transformation to overcome limit which have just one-dimension feature with voltage value for using convolution operation. Then, the reconstructed signal data is finally classified and recognized using multiple learning layers model based on deep learning. Since the statistical model based on probability is sensitive to initial parameters, the result can change after training in modeling phase. Deep learning model can overcome this problem because of several layers in training phase. In experiment, we used two different deep learning structures, Convolutional neural networks and Recurrent Neural Network and compared with statistical model algorithm with four kinds of gestures. The recognition result of method using convolutional neural network is better than other algorithms in EPS gesture signal recognition.

• Journal of the Korean institute of surface engineering
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• v.37 no.2
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• pp.71-75
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• 2004

The technology of $C_{60}$ fullerite films preparation by means of gas-phase deposition and structure of fullerite films are described. A three-channel flow plant was used to obtain fullerite films. The films were deposited in the flow of inert gas under reduced pressure onto a cooled silicon or sapphire substrate placed inside the reaction chamber of the plant. The plant allows one to obtain the films of pure fullerenes and to synthesise the films from fullerene compounds and doped fullerenes. The structure of two types of films were investigated by FE-SEM and SEM techniques: pure fullerite films onto silicon and sapphire substrates as well as compound films were studied by FE-SEM technique. All samples have shown columnar structure with high level of porosity. The synthesis of films composed of fullerene and its compounds for use in electronics is demonstrated to be promising. For example, experiments confirm the possibility to use fullerite films in sensor electronics to produce humidity and thermal sensors. It is also possible to use the sensitivity of these films to isotropic pressure. The experiments with $C_{60}$-Cu-J films have shown quite strong dependence of their resistance on pressure of different sort of medium-gas that could be used in gas-sensitive sensors. The structure and preparation technology of resistive sensor based on fullerite films are described.bed.

• Korean Journal of Microbiology
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• v.38 no.2
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• pp.96-102
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• 2002

The S-phase checkpoint mechanisms response to DNA damage or inhibition of DNA replication for maintenance of genetic stability in eukaryotic cells. These roles include cell cycle control arrest at S-phase and Iranscriptional induction of repair genes. To characterize the defects of dpbll mutant for both these responses, we examined the over-expression effect of DPBll gene, the sensitivity to HU, MMS, and the transcriptional pattern by DNA damage agent for RNRS mRNA. RNRS transcript is induced in response to a wide variety of agents that either damage D7A directly through chemical modification or induce stress by blocking DNA synthesis. As results, dpbll-1 cells are sensitive to DNA damage agents and the level of RNR3 mRNA is reduced approximately 40% than wild type cells. Moreover, we found the same results in dpb2-1 cells. Therefore, we propose that DPB2 and DPBll act as a sensor of replication that coordinates the transcriptional and cell cycle responses to replication blocks.

• Analytical Science and Technology
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• v.11 no.4
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• pp.305-310
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• 1998

A reactive dye synthesized with an amine containing Eriochrome Black T derivative and cynauric chloride was immobilized on a cellulose membrane to construct an optical sensor for the detection of divalent transition metal ions in aqueous solution. The response of this reactive dye-based optical sensor was as sensitive as that of Eriochrome Black T in solution phase. Its typical detection limits for $Zn^{2+}$ and $Co^{2+}$ were $6.3{\times}10^{-5}mol/l$ and $2.5{\times}10^{-4}mol/l$, respectively. No loss in the sensitivity of reactive dye-based sensor was observed even the pH of flowing solutions continually varied for an extended period of time.

• Journal of Korea Multimedia Society
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• v.12 no.11
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• pp.1609-1622
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• 2009

In wireless sensor networks, a clustering protocol is an efficient method to prolong network lifetime. In general, it results in more energy consumption at the cluster-head node. Hence, such a protocol must changes the cluster formation and cluster-head node in each round to prolong the network lifetime. But, this method also causes large amount of energy consumption during the set-up process of cluster formation. In order to improve energy efficiency, in this paper, we propose a new clustering algorithm. In this algorithm, we exclude duplicated data of adjacent nodes and transmits the threshold value. We define a group as the sensor nodes within close proximity of each other. In a group, a node senses and transmits data at a time on the round-robin basis. In a view of whole network, group is treated as one node. During the setup phase of a round, intra clusters are formed first and then they are re-clustered(network cluster) by choosing cluster-heads(group). In the group with a cluster-head, every member node plays the role of cluster-head on the round-robin basis. Hence, we can lengthen periodic round by a factor of group size. As a result of analysis and comparison, our scheme reduces energy consumption of nodes, and improve the efficiency of communications in sensor networks compared with current clustering methods.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1848-1850
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• 2004

변압기에 사용되는 절연유의 열화정도를 변압기의 운전정지 없이 실시간으로 측정할 수 있는 전기용량을 이용한 센서를 개발하였다. 개발된 전기용량형 센서는 3-전극형의 구조와 변압기에 센서의 외부상자가 접지 될 때 2중의 정전차폐가 되도록 하여 외부로부터의 잡음에 영향을 받지 않도록 하였다. 또한 변압기에서 절연유의 온도변화에 따른 유전율 변화를 보상하기위하여 기준용 센서와 측정용 센서를 한개의 변압기에 장착함으로 온도보상이 되도록 하였다. 제작된 센서는 변압기에서 절연유의 사용기간에 따른 유전율의 변화를 정확히 측정하였으며, 절연유의 체적저항의 변화도 감지 할 수가 있다. 따라서 센서에서 출력되는 신호를 phase sensitive detector를 사용하여 유전율의 변화로 혹은 체적저항의 변화로도 나타내 보일 수가 있다.

• Journal of Mechanical Science and Technology
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• v.16 no.4
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• pp.485-491
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• 2002

The gyroscopes have been used as a suitable inertial instrument for the navigation guidance and attitude controls. The accuracy as very sensitive sensor is limited by the lock-in region (dead band) by the frequency coupling between two counter-propagating waves at low rotation rates. This frequency coupling gives no phase difference and an angular increment is not detected. This problem can be overcome by the mechanical dithering. The purpose of the mechanical dithering is to suppress the dead band, oscillate the monoblock about the rotation axis and add an external rotation rate. This paper presents the theoretical considerations of the mechanical performances of dither on the basis of the loading condition and angular characteristics due to the piezoelement deformation and the validity of theoretical equations are compared through FEM (Finite Element Method) simulations.