• Journal of Sensor Science and Technology
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• v.20 no.6
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• pp.375-381
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• 2011

Ionic polymer-metal composite(IPMC) consists of an ion conductive membrane plated by metallic electrodes on both surfaces. When it bends, a voltage is generated between two electrodes. Since IPMC is flexible and thin, it can be easily mounted on the various surfaces of a body. The present study investigates a sensor system using IPMC to effectively detect the bending angles applied on IPMC sensor. The paper evaluates several R and C circuit models that describe the physical composition of IPMC and selects the best model for the detection of angles. The circuit models implemented with a charge model describe the relationship between input bending angles and output voltages. The identification of R and C values was performed by minimizing the error between the real output voltages and the simulated output voltages from the circuit models of IPMC sensor. Then the output signal of a sensor was fed into the inverse model of the identified model to reproduce the bending angles. In order to support the validation of the model, the output voltages from an arbitrary bending motion were also applied to the selected inverse model, which successfully reproduced the arbitrary bending motion.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.943-946
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• 2007

In-plane piezoelectric charge constant of Electro-Active paper (EAPap) was investigated based on direct and converse piezoelectric effects. EAPap samples were made with cellulose film with very thin gold electrode coated on both sides of the film. To characterize direct piezoelectricity of EAPap, induced charge was measured when mechanical stress was applied to EAPap. In-plane piezoelectric charge constant was extracted from the relation between induced charge and applied in-plane normal stress. To investigate converse piezoelectricity, induced in-plane strain was measured when electric field was applied to EAPap. Piezoelectric charge constant was also extracted from the relation of induced in-plane strain and applied electric field. Piezoelectric charge constants obtained from direct and converse piezoelectricity are 31 pC/N and 178 x 10-12m/V for 45 degree sample, respectively. Measured piezoelectric charge constants of EAPap provide promising potential as a piezoelectric material.

• Journal of Mechanical Science and Technology
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• v.18 no.4
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• pp.640-648
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• 2004

This paper describes a new magnetization method for non-destructive testing with magneto-optical sensor (denoted as MO sensor) which have the following characteristic : high observation sensitivity, independence of the crack orientation, and precise imaging of a complex crack geometry such as multiple cracks. When a magnetic field is applied normally to the surface of a specimen which is significantly larger than its defects, approximately the same magnetic charge per unit area occurs on the surface of the specimen. If there is a crack in the specimen, magnetic charge per unit area has the same value at the bottom of the crack. The distribution of the vertical component of the magnetic flux density, B$\_$Z/, is almost uniform over the no-crack area (denoted as B$\_$Z,BASE/), while the magnetic flux density is smaller in the surroundings of the crack(denoted as B$\_$Z,CRACK/) If B$\_$Z, BASE/ is a bit larger than the saturated magnetic flux density of the MO sensor (B$\_$s/) , then small magnetic domains occur over the crack area and a large domain over the non-crack area because B$\_$Z,CRACK/ is smaller than B$\_$s/.

• Journal of IKEEE
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• v.13 no.4
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• pp.63-68
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• 2009

The power management integrated circuit(PMIC) for CCD image sensor is presented in this study. A CCD image sensor is very sensitive against temperature. The temperature, that is heat, is generally generated by the PMIC with low efficiency. Since the generated heat influences performance of CCD image sensor, it should be minimized by using a PMIC which has a high efficiency. In order to develop the PMIC with high efficiency, the input stage is designed with synchronous type step down DC-DC converter. The operating range of the converter is from 5V to 15V and the converter is controlled using PWM method. The PWM control circuit consists of a saw-tooth generator, a band-gap reference circuit, an error amplifier and a comparator circuit. The saw-tooth generator is designed with 1.2MHz oscillation frequency. The comparator is designed with the two stages OP Amp. And the error amplifier has 40dB DC gain and $77^{\circ}$ phase margin. The output of the step down converter is connected to input stage of the charge pump. The output of the charge pump is connected to input of the LDO which is the output stage of the PMIC. Finally, the PMIC, based on the PWM control circuit and the charge pump and the LDO, has output voltage of 15V, -7.5V, 3.3V and 5V. The PMIC is designed with a 0.35um process.

• JSTS:Journal of Semiconductor Technology and Science
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• v.6 no.4
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• pp.293-298
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• 2006

Thermopiezoelectric method, using poly silicon heater and a piezoelectric sensor, was proposed for writing and reading in a probe based data storage system. Resistively heated tip writes data bits while scanning over a polymer media and piezoelectric sensor reads data bits from the self-generated charges induced by the deflection of the cantilever. 34${\times}$34 array of thermopiezoelectric nitride cantilevers were fabricated by a single step wafer level transfer method. We analyzed the noise level of the charge amplifier and measured the noise signal. With the sensor and the charge amplifier 20mn of deflection could be detected at a frequency of 10KHz. Reading signal was obtained from the cantilever array and the sensitivity was calculated.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.693-694
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• 2013

• Journal of Sensor Science and Technology
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• v.21 no.1
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• pp.7-12
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• 2012

In this paper, we propose a 4-transistor active pixel sensor(APS) with a novel correlated double sampling(CDS) circuit for the purpose of extending dynamic range. Dual sampling techniques can overcome low-sensitivity and temporal disparity problems at low illumination. To accomplish this, two images are obtained at the same time using different sensitivities. The novel CDS circuit proposed in this paper contains MOS switches that make it possible for the capacitance of a conventional CDS circuit to function as a charge pump, so that the proposed APS exhibits an extended dynamic range as well as reduced noise. The designed circuit was fabricated by using $0.35{\mu}m$ 2-poly 4-metal standard CMOS technology and its characteristics have been evaluated.

• Journal of Sensor Science and Technology
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• v.25 no.5
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• pp.326-332
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• 2016

A novel CMOS temperature sensor with binary output is implemented by using fully differential switched-capacitor circuits for resistorless implementation of the temperature sensor core. Temperature sensing is based on the temperature characteristics of the pn diodes implemented by substrate pnp transistors fabricated using standard CMOS processes. The binary outputs are generated by using the charge-balance principle that eliminates the division operation of the PTAT voltage by the bandgap reference voltage. The chip was designed in a MagnaChip $0.35-{\mu}m$ CMOS process, and the designed circuit was verified using Spectre circuit simulations. The verified circuit was laid out in an area of $950{\mu}m{\times}557 {\mu}m$ and is currently under fabrication.

• Journal of Sensor Science and Technology
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• v.19 no.5
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• pp.391-397
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• 2010

This paper proposes a differential structure sensor for detecting Ringer's solution exhaustion, in which three C-type electrodes of 10 mm width are disposed on a ringer hose at a distance of 5 mm each other in the direction of Ringer's solution flow. In the center of middle electrode, two capacitances are formed at the proposed sensor. When ringer hose is filled with Ringer's solution, there is no difference between two capacitances. But capacitance difference exist under the Ringer's solution shortage, because the shortage causes the hose filled with air from the top position electrode. The capacitance difference got to maximum 1.81 pF, when air was filled between top and middle electrode and the last of hose was filled with 10 % dextrose injection Ringer's solution. The capacitance difference varied with hose-wraparound coverage of electrodes as well as the width of them. For hose-wraparound electrode coverage of 90 % and 70 %, the maximum capacitance difference was 1.81 pF and 1.56 pF, respectively. A differential charge amplifier converted the capacitance difference to electric signal, and minimized electrodes' adhering problem and external noise coupling problem.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.48 no.2
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• pp.86-90
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• 2011

The effects of cations are very important in field-effect transistors (FETs) type DNA sensors detecting the intrinsic negative charge between single-stranded DNA and double-stranded DNA without labeling, because the intrinsic negative charge of DNA is neutralized by cations in electrolyte solution. We consider the Debye length, which depends on the concentration of cations in solution, to detect DNA hybridization based on the intrinsic negative charge of DNA. The Debye length is longer in buffer solution with a lower concentration of NaCl and the intrinsic negative charge of DNA is more effective on the channel surface in longer Debye length solution. The shifts in the gate voltage by DNA hybridization with complementary target DNA are 21 mV in 1 mM NaCl buffer solution, 7.2 mV in 10 mM NaCl buffer solution, and 5.1 mV in 100 mM NaCl buffer solution. The sensitivity of FETs to detect DNA hybridization based on charge detection without labeling depends on the Debye length.