• Journal of Sensor Science and Technology
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• v.13 no.4
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• pp.316-320
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• 2004

The possibility to use powder consisting of fullerite microcrystallines as a device sensitive to the external axial mechanical load is considered. We suppose that the change of conductivity of fullerite microcrystalline powder as a function of external mechanical stress will be useful for the creation of nanoscale devices of sensor electronics. This new effect based on changing of intermolecular distance between fullerene molecules due to the action of external mechanical force, which can change the distance between fullerene molecules because of weak van der Waals interaction exists. The founded effect is quite linear and sensitive to external mechanical stress is better then in well-known pressure transducers is based on silicon technology.

• Ocean and Polar Research
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• v.36 no.1
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• pp.77-85
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• 2014

The quality control of ocean observations data is becoming a major issue as real-time observational data and information services have increased recently. Therefore, it is necessary for oceanographic instruments to calibrate. In this paper, we first introduce the CTD calibration system and traceability. Next, CTD calibration procedures and estimation of uncertainty of measurement are described. The expanded uncertainty (k = 2) of the temperature, pressure and conductivity are 0.$0.003^{\circ}C$, $6.0{\times}10^{-5}$ and 0.006 mS/cm respectively. Finally, the excellence of CTD calibration and its measurement capability has been proven by comparing the inter-calibration result of KIOST and Sea-Bird Electronics (SBE). CTD calibration residuals are less than ${\pm}0.0001^{\circ}C$, ${\pm}0.001$ MPa, ${\pm}0.0001$ S/m for SBE 3plus temperature sensor, SBE 19plus pressure sensor and SBE 4C conductivity sensor respectively.

• Composites Research
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• v.23 no.3
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• pp.31-36
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• 2010

A new material, carbon-nanofiber/polypyrrole (CNF/PPy) composite films, with different CNF weight ratios were fabricated electrochemically. Compared to the fabrication process based on simple physical mixing, the flexibility of the new film has been improved much better than the previous similar material. Pure PPy films were also fabricated by the new electrochemical process for the comparison of difference. Several SEM images were taken at two locations (electrode-side and solution-side) and at the cross section of the samples. Electrical conductivity of the composite films was measured by the four-probe method. The conductivity of the pure PPy film 0.013cm thick was 79.33S/cm. The CNF/PPy composite film with 5% CNF showed a conductivity of 93S/cm. One with 10% CNF showed a conductivity of 126 S/cm. The conductivity of PPy improves, as the CNF weight ratio increases. The good conductivity of CNF/PPy composites makes them a candidate for a small bending actuator. A bending sensor consists of PPy and PVDF, which can be operated in the air, was designed and the bending deflection was calculated using FEM.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.905-906
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• 2012

• Journal of Electrical Engineering and Technology
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• v.10 no.1
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• pp.364-371
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• 2015

In this study, we developed a feasible structure of a textile-based inductive sensor using a machine embroidery method, and applied it to a non-contact type vital sign sensing device based on the principle of magnetic-induced conductivity. The mechanical heart activity signals acquired through the inductive sensor embroidered with conductive textile on fabric were compared with the Lead II ECG signals and with respiration signals, which were simultaneously measured in every case with five subjects. The analysis result showed that the locations of the R-peak in the ECG signal were highly associated with sharp peaks in the signals obtained through the textile-based inductive sensor (r=0.9681). Based on the results, we determined the feasibility of the developed textile-based inductive sensor as a measurement device for the heart rate and respiration characteristics.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.81-81
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• 2008

Applications of CdS films in this study are to exhibit a high conductivity when they are exposed at light with visible wavelength and sequentially to show a low conductivity in dark state. For this purpose, CdS films should have a high photosensitivity, still maintaining a high conductivity at a visible light. In this study, CdS films were prepared at room temperature on glass substrates by rf magnetron sputtering. In order to increase the photo-conductivity in visible light, various defect levels should be located within the CdS band gap. In order to nucleate the defect sites within the CdS band gap, CdS films were deposited on glass substrates at room temperature using various $H_2$/(Ar+$H_2$) flow ratios by an rf magnetron sputtering. Through the investigation of the structural and photoconductive properties of CdS films by an addition of hydrogen, the relationship between photo- and dark-resistance in CdS films was investigated in detail. 200-nm-thick CdS films for photoconductive sensor applications were prepared at various $H_2$/(Ar+$H_2$) flow ratios on glass substrates at room temperature by rf magnetron sputtering. Sulfur concentration in CdS films crystallized at room temperature with (002) preferred orientation depends directly on the hydrogen atmosphere and the surface roughness of the films gradually increases with increasing hydrogen atmosphere. Films deposited at 8% of $H_2$/(Ar+$H_2$) exhibit an abrupt decrease of dark- and photo-resistance, showing a low photo-sensitivity ($R_{dark}/R_{photo}$). Onthe other hand, films deposited at a hydrogen atmosphere of 42% exhibit a photo-sensitivity of $5\times10^3$, maintaining a photo-resistance of an approximately $2\times10^4\Omega$/square. The dark- and photo-resistance values of CdS films were related with a composition, surface roughness, and defect sites within the band gap.

• Journal of Multimedia Information System
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• v.5 no.3
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• pp.215-220
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• 2018

This work presents a smart water quality sensor for hydroponic plant growing applications. The proposed sensor can effectively measure pH level and electrical conductivity of the water solution. The micro-controller incorporated in the sensor processes the raw sensor data, and converts it into a readable format. In addition, through the mobile interface realized using a WiFi module, the sensor can send data to the web server database that collects and stores the data. The data stored in the web server can be accessed by a personal computer or smart phone. The prototype sensor has been implemented, and the operations have been verified under an actual hydroponic plant growing application.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2171-2176
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• 2007

The 3-omega (3-${\omega}$) method is utilized to measure the thermal conductivity of nanofluids. A metal line heater on a silicon nitride membrane bridge structure is microfabricated by a bulk silicon etching method. Localized measurement of the thermal conductivity within the nanofluids droplet is possible by the fabricated 3-${\omega}$ sensor. Time varying AC temperature amplitudes and thermal conductivities are measured to check the stability of the nanofluids containing multi-wall carbon nanotubes (MWCNTs). Stabilities of MWCNT nanofluids prepared with different chemical treatments are compared. Acid treated MWCNT showed best dispersion stability in water while MWCNTs dispersed in water with surfactants such as Gum Arabic and Sodium dodecyl benzene sulfate showed clear sign of gravity dependence.

• Journal of Sensor Science and Technology
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• v.13 no.5
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• pp.392-398
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• 2004

It is known that the conductivity of fullerite depends on the applied pressure. In this paper we compare the variation of conductivity of three different fullerite structure with pressure. We examined $C_{60}$ powder, filled into thin glass capillaries and also studied fullerite nanotubules produced within etched swift heavy ion tracks in polymer foils. These investigations are compared with the results of planar Si-$C_{60}$-Au structures.

• Macromolecular Research
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• v.10 no.6
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• pp.345-358
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• 2002

The electrical conductivity during vulcanization process was measured as a function of time for the system of TiC loaded styrene-butadiene rubber (SBR) composites. The phenomenon of negative and positive temperature coefficients of conductivity and its conduction mechanism were also studied for the SBR polymeric composites. The current-voltage characteristics of the polymeric composites were non-linear in high voltage and showed a switching effect. The effects of temperature on the thermal conductivity and effective dielectric constant were measured. The measured parameters were found to be dependent on TiC concentration. The electromagnetic wave shielding (EMS) of the SBR-TiC polymeric composite was also examined. The SBR filled with TiC could be expected to be promising novel smart polymeric composites for self-electrical heating, temperature sensor, time delay switching, and electro-magnetic wave shielding effectiveness.