• Journal of the Korean Chemical Society
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• v.43 no.3
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• pp.271-279
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• 1999

A new enzyme electrode was developed by co-mobilization of chicken small intestinal tissue and ferrocene in a carbon paste for the determination of hydrogen peroxide, and its electrochemical properties are evaluated. The electrode showed the response time(t100%) as short as 3 set, the detection limit of 5.0${\times}$10-5 M,and a good selectivity for the possible interferents tested. The electrode also offered a good linearity in calibration, a higher biocatalytic stability and a larger responding signal as compared with the other animal or plant tissue based sensors.

• Journal of Radiation Protection and Research
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• v.10 no.1
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• pp.64-66
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• 1985

A methylene blue-PVA system has been tested as a krad range dosimeter. Mb dye films were fabricated by casting PVA in solution with the methylene blue. In the air the system was irradiated by X-ray and the decolorisation of the dye film was found to remain unchanged for sufficiently long time. The radiation response on optical density at 670 nm in the Mb-PVA system shows a quite good linearity and reproducibility in the krad range.

• Journal of the Korea Society of Computer and Information
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• v.3 no.2
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• pp.77-84
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• 1998

The continuous time signal system by development of CMOS technology have been receiving consideration attention. In this paper, Low pass filter using CMOS floating resistor have been designed with cut off frequency for speech signal processing. Especially a new floating resistor consisting entirely of CMOS devices in saturation has been developed. Linearity within $\pm$0.04% is achieved through nonlineartiy via current mirrors over an applied range of $\pm$1V. The frequency response exceeds 10MHz, and the resistors are expected to be useful in implementing integrated circuit active RC filters. The low pass filter designed using this method has simpler structure than switched capacitor filter. So reduce the chip area. The characteristics of the designed low pass filter using this method are simulated by pspice program.

• Journal of Radiation Protection and Research
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• v.22 no.2
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• pp.85-95
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• 1997

TLD and film badges have been traditionally used as formal dosimeters in personal monitoring and are still most widely used. Recently, electronic personal dosimeters based upon Si diode or miniature G-M tube were developed and are getting attractions due to their merits of active nature ; indication of dose rates and the commutative dose, and facilitation of record keeping and radiological control. Response characteristics of the electronic dosimeters including reproducibility, accuracy, linearity, energy and angular dependencies, detection threshold, and response time were examined for three commercial types ; EPD2, STEPHEN6000, and PD-3i. The results were compared with the relevant requirements of IEC standards and Ontario Hydro standards to conclude that their general performances were good. Some specific deficiencies, e.g. incapability of shallow dose measurement of STEPHEN6000, and PD-3i, however, should be corrected to be used as a formal dosimeter.

• Wind and Structures
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• v.19 no.4
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• pp.421-441
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• 2014

With the assistance of typhoon field data at aerial elevation level observed by meteorological satellites and wind velocity and direction records nearby the ground gathered in Guangzhou Weather Station between 1985 and 2001, some key wind field parameters under typhoon climate in Guangzhou region were calibrated based on Monte-Carlo stochastic algorithm and Meng's typhoon numerical model. By using Peak Over Threshold method (POT) and Generalized Pareto Distribution (GPD), Wind field characteristics during typhoons for various return periods in several typical engineering fields were predicted, showing that some distribution rules in relation to gradient height of atmosphere boundary layer, power-law component of wind profile, gust factor and extreme wind velocity at 1-3s time interval are obviously different from corresponding items in Chinese wind load Codes. In order to evaluate the influence of typhoon field parameters on long-span flexible bridges, 1:100 reduced-scale wind field of type B terrain was reillustrated under typhoon and normal conditions utilizing passive turbulence generators in TJ-3 wind tunnel, and wind-induced performance tests of aero-elastic model of long-span Guangzhou Xinguang arch bridge were carried out as well. Furthermore, aerodynamic admittance function about lattice cross section in mid-span arch lib under the condition of higher turbulence intensity of typhoon field was identified via using high-frequency force-measured balance. Based on identified aerodynamic admittance expressions, Wind-induced stochastic vibration of Xinguang arch bridge under typhoon and normal climates was calculated and compared, considering structural geometrical non-linearity, stochastic wind attack angle effects, etc. Thus, the aerodynamic response characteristics under typhoon and normal conditions can be illustrated and checked, which are of satisfactory response results for different oncoming wind velocities with resemblance to those wind tunnel testing data under the two types of climate modes.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.330-330
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• 2007

Polycrystalline mercuric iodide $HgI_2$) films are being developed as a new detector technology for digital x-ray imaging. The $HgI_2$ is generally vacuum deposited by physical vapor deposition (PVD) process. But the PVD thick deposition has been caused any instability in the biasing due to any defects or cracks. In this work we present a new particle-in-binder (PIB) methodologies used for the $HgI_2$ thick films. These growth techniques can be easily extended to produce much larger film areas. This paper, for the first time, presents results and comparison of polycrystalline $HgI_2$ films derived by various PIB methods. We investigated the structural and morphological properties of the films using X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis. The films were characterized with respect to their electrical properties and in response to x-ray photons. Physical and electrical results were also compared between conventional polycrystalline PVD and our detectors. Leakage current as low as $350\;pA/cm^2$ at the bias voltage of ~ 200 V has been observed. And high sensitivity and good linearity in the response to x-rays was obtained in the film derived by PIB sedimentation method. Our future efforts will concentrate on optimization of film growth techniques for uniform large area deposition on image readout arrays.

• Journal of Sensor Science and Technology
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• v.7 no.4
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• pp.271-278
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• 1998

A ISFET-based glucose sensor has inherent problems such as low sensitivity, drift effect and long response time. For that reason, a amperometric actuation technique was introduce to make a highly sensitivity of the ISFET glucose sensor with a Pt actuator, which electrolyzes $H_2O_2$, one of the by a by-products of the oxidation reaction of glucose. Moreover, a potential-step measurement method detecting response by only the electrolysis of $H_2O_2$ was developed for eliminating a drift problem. The operation characteristics of ISFET-based glucose sensor was improved by using the amperometric actuation and a measurement techniques. The fabricated ISFET glucose sensor is shown good operation such as characteristics(30mM PBS, about 26mV/decade) and linearity. A portable glucose meter with a highly resolution by using the fabricated ISFET-based glucose sensor with Pt actuation was developed and its characteristics investigated.

• The Journal of Korean Society for Radiation Therapy
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• v.22 no.2
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• pp.123-129
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• 2010

Purpose: The purpose of this study was to evaluate dosimetric characteristics of Optically stimulated luminescent dosimeters (OSLD) for dosimetry Materials and Methods: InLight/OSL $NanoDot^{TM}$ dosimeters was used including $Inlight^{TM}MicroStar$ Reader, Solid Water Phantom, and Linear accelerator ($TRYLOGY^{(R)}$) OSLDs were placed at a Dmax in a solid water phantom and were irradiated with 100 cGy of 6 MV X-rays. Most irradiations were carried out using an SSD set up 100 cm, $10{\times}10\;cm^2$ field and 300 MU/min. The time dependence were measured at 10 minute intervals. The dose dependence were measured from 50 cGy to 600 cGy. The energy dependence was measured for nominal photon beam energies of 6, 15 MV and electron beam energies of 4-20 MeV. The dose rate dependence were also measured for dose rates of 100-1,000 MU/min. Finally, the PDD was measured by OSLDs and Ion-chamber. Results: The reproducibility of OSLD according to the Time flow was evaluated within ${\pm}2.5%$. The result of Linearity of OSLD, the dose was increased linearly up to about the 300 cGy and increased supralinearly above the 300 cGy. Energy and dose rate dependence of the response of OSL detectors were evaluated within ${\pm}2%$ and ${\pm}3%$. $PDD_{10}$ and PDD20 which were measured by OSLD was 66.7%, 38.4% and $PDD_{10}$ and $PDD_{20}$ which were measured by Ion-chamber was 66.6%, 38.3% Conclusion: As a result of analyzing characteration of OSLD, OSLD was evaluated within ${\pm}3%$ according to the change of the time, enregy and dose rate. The $PDD_{10}$ and $PDD_{20}$ are measured by OSLD and ion-chamber were evaluated within 0.3%. The OSL response is linear with a dose in the range 50~300 cGy. It was possible to repeat measurement many times and progress of the measurement of reading is easy. So the stability of the system and linear dose response relationship make it a good for dosimetry.

• Journal of the Korean Chemical Society
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• v.34 no.5
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• pp.424-429
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• 1990

A bio-sensor for the determination of glucose has been constructed by immobilizing the Citrobacter freundii or its organelle on carbon dioxide gas-sensor. The bacterial sensor was better than organelle in response, but the latter showed a shorter response time. The bacterial sensor gave linearity between 7.0 ${\times}\;10^{-4}$ and 1.0 ${\times}\;10^{-2}$ M glucose with a slope of 42.2 mV/decade in pH 7.0, 0.2 M tris-HCl buffer at 30$^{\circ}C$. The selectivity of this sensor was very high for glucose. Employing for the determination of glucose in serum, the sensor showed a good agreement with a routine analyzer.

• Smart Structures and Systems
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• v.19 no.2
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• pp.181-194
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• 2017

In order to investigate the interface debonding defects detection mechanism between steel tube and concrete core of concrete-filled steel tubes (CFSTs), multi-physical fields coupling finite element models constituted of a surface mounted Piezoceramic Lead Zirconate Titanate (PZT) actuator, an embedded PZT sensor and a circular cross section of CFST column are established. The stress wave initiation and propagation induced by the PZT actuator under sinusoidal and sweep frequency excitations are simulated with a two dimensional (2D) plain strain analysis and the difference of stress wave fields close to the interface debonding defect and within the cross section of the CFST members without and with debonding defects are compared in time domain. The linearity and stability of the embedded PZT response under sinusoidal signals with different frequencies and amplitudes are validated. The relationship between the amplitudes of stress wave and the measurement distances in a healthy CFST cross section is also studied. Meanwhile, the responses of PZT sensor under both sinusoidal and sweep frequency excitations are compared and the influence of debonding defect depth and length on the output voltage is also illustrated. The results show the output voltage signal amplitude and head wave arriving time are affected significantly by debonding defects. Moreover, the measurement of PZT sensor is sensitive to the initiation of interface debonding defects. Furthermore, wavelet packet analysis on the voltage signal under sweep frequency excitations is carried out and a normalized wavelet packet energy index (NWPEI) is defined to identify the interfacial debonding. The value of NWPEI attenuates with the increase in the dimension of debonding defects. The results help understand the debonding defects detection mechanism for circular CFST members with PZT technique.