• Journal of Sensor Science and Technology
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• v.9 no.2
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• pp.106-112
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• 2000

A FET-type reference electrode(REFET) is an effective method to eliminate typical problems with ISFET(ion sensitive field-effect transistor) such as drift, temperature, light-dependence and miniaturization of reference electrode. However, it is difficult to make the highly reliable REFET with excellent long-term stability and reproducibility. In this paper, an ion-blocking membrane was applied to the REFET for the PET-type electrolyte sensors(pH, pNa-ISFET). The fabricated REFET indicated the stable sensitivity (55.4 mV/pH, 53.5 mV/decade) and good linearity in the pH and pNa measurement. In the measurement, ISFET/Pt/REFET configuration showed excellent stability and reproducibility.

• Journal of Sensor Science and Technology
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• v.16 no.1
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• pp.7-10
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• 2007

A thick film catalytic gas sensors which can be operated at $142^{\circ}C$ in presence of ultra violet-light emitting diode has been developed to measure hydrogen concentration in 0-5 % range. The sensing material as a combustion catalyst consists of $TiO_{2}$ (5 wt%) and Pd/Pt (20 wt%) supported on $Al_{2}O_{3}$ powder and the reference material to compensate the heat capacity of it in a bridge circuit was an catalyst free $Al_{2}O_{3}$ powder. Platinum heater and sensor materials were formed on the alumina plate by screen printing method and heat treatment. The effect of UV radiation in the presence of photo catalyst $TiO_{2}$ on the sensor sensitivity, response and recovery time has been investigated. The reduction of operating temperature from $192^{\circ}C$ to $142^{\circ}C$ for hydrogen gas sensing property in presence of UV radiation is attributed to the hydroxy radical and superoxide which was formed at the surface of $TiO_{2}$ under UV radiation.

• Journal of Soil and Groundwater Environment
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• v.20 no.6
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• pp.19-27
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• 2015

Permissible soil concentrations for explosives (i.e., TNT and RDX) and heavy metals (i.e., Cu, Zn, Pb, and As) heve been derived from human risk and ecotoxicity, respectively. For TNT and RDX, human risk based-permissible soil concentrations were determined as 460 mg-TNT/kg-soil and 260 mg-RDX/kg-soil. Ecotoxicity based-permissible soil concentrations for Cu and Zn were determined from species sensitivity distribution (SSD) and uncertainty factor of 1 to 5, yielding 18.0-40.0 mg-Cu/kg-soil and 46.0-100 mg-Zn/kg-soil. For Pb and As, ecotoxicity data were not enough to establish SSD so that a deterministic method was used, generating 13.8-30.8 mg-Pb/kg-soil and 2.10-4.60 mg-As/kg-soil. It is worth noting that the methodology used to derive permissible concentrations in soil can differ depending on ecotoxicity data availability and socio-economic situations, which results in different permissible concentrations. The permissible concentrations presented in this study have been derived from conservative assumptions for exposure parameters, and thus should be considered as soil standards. In the light of remediation and pollution management of a site of interest, the site-specific and receptor-specific permissible soil concentrations should be derived considering potential receptors, current and future land use, background concentrations, and socio-economic consultation.

• Korean Journal of Materials Research
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• v.23 no.9
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• pp.477-482
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• 2013

We investigated the detection properties of nitrogen monoxide (NO) gas using transparent p-type $CuAlO_2$ thin film gas sensors. The $CuAlO_2$ film was fabricated on an indium tin oxide (ITO)/glass substrate by pulsed laser deposition (PLD), and then the transparent p-type $CuAlO_2$ active layer was formed by annealing. Structural and optical characterizations revealed that the transparent p-type $CuAlO_2$ layer with a thickness of around 200 nm had a non-crystalline structure, showing a quite flat surface and a high transparency above 65 % in the range of visible light. From the NO gas sensing measurements, it was found that the transparent p-type $CuAlO_2$ thin film gas sensors exhibited the maximum sensitivity to NO gas in dry air at an operating temperature of $180^{\circ}C$. We also found that these $CuAlO_2$ thin film gas sensors showed reversible and reliable electrical resistance-response to NO gas in the operating temperature range. These results indicate that the transparent p-type semiconductor $CuAlO_2$ thin films are very promising for application as sensing materials for gas sensors, in particular, various types of transparent p-n junction gas sensors. Also, these transparent p-type semiconductor $CuAlO_2$ thin films could be combined with an n-type oxide semiconductor to fabricate p-n heterojunction oxide semiconductor gas sensors.

• Journal of the Korean Society of Visualization
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• v.5 no.1
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• pp.9-11
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• 2007

We introduce an in vivo imaging flow cytometer, which provides fluorescence images simultaneously with quantitative information on the cell population of interest in a live animal. As fluorescent cells pass through the slit of light focused across a blood vessel, the excited fluorescence is confocally detected. This cell signal triggers a strobe beam and a high sensitivity CCD camera that captures a snap-shot image of the cell as it moves down-stream from the slit. We demonstrate that the majority of signal peaks detected in the in vivo flow cytometer arise from individual cells. The instrument's capability to image circulating T cells and measure their speed in the blood vessel in real time in vivo is demonstrated. The cell signal irradiance variation, clustering percentage, and potential applications in biology and medicine are discussed.

• Journal of Korean Neurosurgical Society
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• v.58 no.4
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• pp.363-367
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• 2015

Objective : The purpose of this study was to evaluate the clinical utility and validity of using a pupillometer to assess patients with acute brain lesions. Methods : Pupillary examinations using an automated pupillometer ($NeurOptics^{(R)}NPi^{TM}$-100 Pupillometer) were performed every 4 hours and were simultaneously assessed using the Glasgow Coma Scale (GCS) and for intracranial pressure (ICP), from admission to discharge or expire in neuro-intensive care unit (NICU). Manual pupillary examinations were also recorded for comparison. By comparing these data, we evaluated the validity of using automated pupillometers to predict clinical outcomes. Results : The mean values of the Neurologic Pupillary index (NPi) were different in the groups examined manually. The GCS correlated well with NPi values, especially in severe brain injury patients (GCS below 9). However, the NPi values were weakly correlated with intracranial pressure (ICP) when the ICP was lower than 30 cm $H_2O$. The NPi value was not affected by age or intensity of illumination. In patients with a "poor" prognosis who had a Glasgow Outcome Scale (GOS) of 1 or 2, the mean initial NPi score was $0.88{\pm}1.68$, whereas the value was $3.89{\pm}0.97$ in patients with a "favorable" prognosis who had a GOS greater than 2 (p<0.001). For predicting clinical outcomes, the initial NPi value of 3.4 had the highest sensitivity and specificity. Conclusion : An automated pupillometer can serve as a simple and useful tool for the accurate measurement of pupillary reactivity in patients with acute brain lesions.

• The Journal of the Korea Contents Association
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• v.8 no.6
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• pp.8-15
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• 2008

In this paper, in order to analyze property of frequency response in optical microphone, system was implemented. The capacitance microphone and fiber-optic transmission path type fiber-optic microphone (FOM) have weaknesses in directivity, size, weight, and price. However suggested optical microphone can be constituted by cheap devices, so it has many benefits like small size, light weight, high directivity, etc. Head part of optical microphone which is suggested in this paper is movable back and forth by sound pressure with the attached reflection plate. Operating point is determined by measuring the respond characteristics and choosing the point on which has maximum linearity and sensitivity while changing the distance between optical head and vibrating plate. We measured the output of the O/E transformed signal of the optical microphone while frequency of sound signal is changed using sound measurement/analysis program, Smaart Live and USBPre, which are based on PC, and compared the result from an existing capacitance microphone. The measured Optical microphone showed almost similar output characteristics as those of the compared condenser microphone, and its bandwidth performance was about 300[Hz]-3[kHz] at up to 3 [dB].

• Journal of Microbiology and Biotechnology
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• v.26 no.3
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• pp.530-539
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• 2016

Bacterial light-oxygen-voltage-sensing photoreceptor-derived flavin mononucleotide (FMN)-based fluorescent proteins act as a promising distinct class of fluorescent proteins utilized for various biomedical and biotechnological applications. The key property of its independency towards oxygen for its chromophore maturation has greatly helped this protein to outperform the other fluorescent proteins such as GFP and DsRed for anaerobic applications. Here, we describe the feasibility of FMN-containing fluorescent protein FbFP as a metal-sensing probe by measuring the fluorescence emission changes of a protein with respect to the concentration of metal ions. In the present study, we demonstrated the mercury-sensing ability of FbFP protein and the possible amino acids responsible for metal binding. A ratiometric approach was employed here in order to exploit the fluorescence changes observed at two different emission maxima with respect to Hg²⁺ at micromolar concentration. The engineered variant FbFP_C56I showed high sensitivity towards Hg²⁺ and followed a good linear relationship from 0.1 to 3 μM of Hg²⁺. Thus, further engineering with a rational approach would enable the FbFP to be developed as a novel and highly selective and sensitive biosensor for other toxic heavy metal ions as well.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.18 no.1
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• pp.221-233
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• 2005

Background and Objectives : Despite of high prevalence, Tinnitus remains obscure because the cause and mechanism is poorly understood. In the absence of a suitable animal model, past investigations tool place in humans. Recently, the animal model with sodium salicylate ototoxicity is broadly used because of its reversibility. Balyangtongum-Tang had been used clinically to treat tinnitus and other hearing problems. We investigated the effects of Balyangtongum-Tang on cochlear morphologic change induced by sodium salicylate ototoxicity and were to find out its therapeutic effects on ototoxicity in rat model. Materials and Methods : Healthy ten Sprague-Dawley rats were divided into normal(2), control(4) and sample(4) groups. The sample group was given extract of Balyangtongum - Tang(1cc/100g) once a day for 4 days. After 3 hours when last medication were given, the sample and control groups were injected intraperitoneally with sodium salicylate(500mg/kg). We observed the cochlear morphologic changes of rats every 1, 2, 3 and 5 hours after injection. Results : The electron microscopic finding of outer hair cell shows some changes in the curticular plate and cytoplasm. Some vacuoles were found in the control and sample groups. Vacuolization in the curticular plate and cytoplasm of the sample group after 3, 5 hours were similar to the control group. But the curticular plate of the sample group after 1, 2 hours did not from vacuole. On the other hand the control group after 1, 2 hours formed vacuoles in the curticular plate. Light microscopic findings of cochlear duct in control and sample groups didn't find any difference. Conclusion : The results suggest that extract of Balyangtongum-Tang reduces the morphologic changes induced by sodium salicylate ototoxicity and the effects are remarkable in frist 2 hours. However the effective times are different with previous studies, it seems to due to the difference of tolerance and sensitivity of laboratory animals.

• Korean Journal of Optics and Photonics
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• v.20 no.3
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• pp.143-147
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• 2009

We propose an asymmetrical 2.5 Gbps / 622 Mbps bidirectional optical subscriber network with Manchester coded downstream and NRZ (Non-Return-to-Zero) upstream remodulation. The proposed system has important characteristics in the optical network unit (ONU): it does not require a light source or the usual control circuits such as wavelength control and output power control, and it is possible to use a synchronization scheme between upstream and downstream data. We theoretically analyze BER(Bit Error Rate) performance of upstream data remodulated with Manchester coded downstream according to the types of NRZ downstream data and perform simulations with MATLAB. The BER performance and the receiver sensitivity have been improved by 3 dB by adjusting threshold levels compared to the conventional receiver. The results have shown the remodulation scheme with Manchester coded downstream could be a useful technology for asynchronous and asymmetric optical subscriber networks with low cost and simple structures.