• KSBB Journal
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• v.20 no.4
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• pp.291-298
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• 2005

Two-dimensional (2D) spectrofluorometer is often used to monitor various fermentation processes. The change in fluorescence intensities resulting from various combinations of excitation and emission wavelengths is investigated by using a spectra subtraction technique. But it has a limited capacity to classify the entire fluorescence spectra gathered during fermentations and to extract some useful information from the data. This study shows that the self-organizing map (SOM) is a useful and interpretative method for classification of the entire gamut of fluorescence spectral data and selection of some combinations of excitation and emission wavelengths, which have useful fluorometric information. Some results such as normalized weights and variances indicate that the SOM network is capable of interpreting the fermentation processes of S. cerevisiae and recombinant E. coli monitored by a 2D spectrofluorometer.

• Korean Journal of Agricultural Science
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• v.47 no.1
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• pp.43-58
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• 2020

Mulching plastic is used for the purpose of maintaining soil temperature, moisture, and weed and pest prevention in agriculture. Any remaining plastic after use may contaminate the soil and damage crop growth. To solve this problem, mulching plastic wrappers have been studied and developed, but the actual use rate is quite low due to their poor performance and frequent tearing of the plastic on the field. In this study, we developed a tractor attachable mulching plastic wrapper to minimize the tearing of the mulched plastic. The developed mulching plastic wrapper consists of hydraulic motors and pumps, valves, a microcontroller, and sensors. The collecting speed of the plastic mulch was calculated considering the tractor's travel speed and the radius of the collecting drum. A proportional controller was designed to control the rotating speed of the hydraulic motor as the plastic was wound around the collection drum and the radius increased. The performance of an indoor experiment was quite promising because the difference between the collecting speed predicted by the calculation and the actual collecting speed was 2.71 rpm. Based on a field verification test, the speed difference was max. 14.28 rpm; thus, the, proportional integral derivative (PID) controller needs to be considered to control the drum speed precisely. Another issue was found when the soil covered at the edge of the plastic was hardened or the road surface was uneven, the speed control was unstable, and the plastic was torn. In future research, vibrational plows will be equipped to break-up the harden soil for collecting the plastic smoothly.

• Journal of Sensor Science and Technology
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• v.24 no.1
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• pp.22-28
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• 2015

This study demonstrates a polyimide nerve cuff electrode with a conductive polymer for improving recording signal quality at peripheral nerve. The nerve cuff electrodes with platinum (Pt), iridium oxide (IrOx), and poly(3,4-ethylenedioxythiophene): p-toluene sulfonate (PEDOT:pTS) were fabricated and investigated their electrical characteristics for improving recorded nerve signal quality. The fabricated nerve cuff electrodes with Pt, IrOx, and PEDOT:pTS were characterized their impedance and CDC by using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry. The impedance of PEDOT:pTS measured at 1 kHz was $257{\Omega}$, which was extremely lower than the value of the nerve cuff electrodes with IrOx ($15897{\Omega}$) and Pt ($952{\Omega}$), respectively. Furthermore, the charge delivery capacity (CDC) of the nerve cuff electrode with PEDOT:pTS was dramatically increased to 62 times than the nerve cuff electrode with IrOx. In ex-vivo test using extracted sciatic nerve of spaque-dawley rat (SD rat), the PEDOT:pTS group exhibited higher signal-to-interference ratio than IrOx group. These results indicated that the nerve cuff electrode with PEDOT:pTS is promising for effective implantable nerve signal recording.

• Journal of Sensor Science and Technology
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• v.27 no.1
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• pp.55-58
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• 2018

Low-cost and large-scale fabrication method of nanohole array, which comprises nanoscale voids separated by a few tens to a few hundreds of nanometers, has opened up new possibilities in biomolecular sensing as well as novel frontier optical devices. One of the key aspects of the nanohole array research is how to control the hole size following each specific needs of the hole structure. Here, we report the extensive study on the fine control of the hole size within the range of 500-2500 nm via surface-catalyzed chemical deposition. The initial hole structures were prepared via conventional photo-lithography, and the hole size was decreased to a designed value through the surface-catalyzed chemical reduction of the gold ion on the predefined hole surfaces, by simple dipping of the hole array device into the aqueous solution of gold chloride and hydroxylamine. The final hole size was controlled by adjusting reaction time, and the optimal experimental condition was obtained by doing a series of characterization experiments. The characterization of size-controlled hole array was systematically examined on the image results of optical microscopy, field emission scanning electron microscopy(FESEM), atomic-force microscopy(AFM), and total internal reflection microscopy.

• Korean Journal of Optics and Photonics
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• v.19 no.3
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• pp.193-198
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• 2008

A novel refractive index sensor, which consists of polymer channel waveguide overlaid with $TiO_2$ thin film, is demonstrated. To evaluate the fabricated sensor, we measured the polarimetric interference induced by concentration change of injected glycerol solution. Our experimental results show that thicker $TiO_2$ film improves the sensitivity of the polarimetric interferometer. For the fabricated waveguide with a 20 nm thick $TiO_2$ film, the measured index change to lead phase variation of $2{\pi}$ is $1.8{\times}10^{-3}$.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.9
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• pp.1749-1754
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• 2007

In this paper, we propose a new Intra-body communication system for bio-sensor which is one of applications in PAN(Personal Area Network) using body channel. The communication systems for bio-sensor network usually transmits a lot of data acquired in sensor to the receiver in wrist or waist. So we deign the intra-body modem with high data rate, low power, and small size which are achieved by baseband communication techniques. It is noted that the baseband transmission does not requires any analog IF and RF frontends, and can be operated in lower frequency than bandpass transmission. The proposed modem operates at 10MHz band according to the characteristics of intra-body channel, and shows the capability of 5Mbps data rate at distance of 20cm, with $BER=10^{-5}$. In addition, we implement the modem within $2{\times}2cm$ area.

• Journal of IKEEE
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• v.25 no.3
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• pp.445-450
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• 2021

Bio-impedance measurement is a measurement device that can be used to obtain biometric information and diagnose skin diseases using convenience, low cost, and low cost devices. In this study, the bio-impedance was measured using a direct dry gold electrode and a simulation study through animal bio modeling to obtain biometric information in a biometric form. Impedance was measured by inserting electrodes into subcutaneous areas of animal tissue and applying frequencies of 100 uA, 1-100 kHz using a two-electrode method. As a result of the measurement, the resistance of the electrodes is measured high at 5 mm electrodes compared to 7.5 mm and 10 mm electrodes based on 5 mm electrodes. Based on the 5 mm electrode, an average difference of 1.49% was found for the 7.5 mm electrode in the total frequency range, and the impedance difference was confirmed to be 2.624% for the 10 mm electrode. In the future, the research results are expected to be valuable in designing and manufacturing electrodes for bio-inserted electrocardiogram sensors.

• Journal of Bio-Environment Control
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• v.18 no.3
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• pp.238-243
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• 2009

To investigate the characteristics of moisture content (MC), moisture distribution and starting point of drainage in a rockwool slab culture, time domain reflectometry (TDR) sensors were used in a drip irrigation system. MC values ($0{\sim}100%$) measured by TDR sensors in a slab were compared to those by loadcells. Seventy two seedlings of paprika (Capsicum annuum L.) were cultured for $5{\sim}6$ months in a green-house and the starting point of irrigation was determined by the average value of three TDR sensors which were inserted diagonally across the slabs under the plants. MCs as a standard for starting point of irrigation by TDR were determined with 40%, 50%, and 60%. Distribution of MCs in a slab measured with five TDR sensors equally spaced from two irrigation points were not much different when the MC in the slab increased from zero to saturation point. The saturated MCs in the slab were presented at $58{\sim}65%$ and the drain was started when the MC became around $50{\sim}55%$. At the saturated MC in the slab, TDR sensors presented 100% but the values from the loadcell showed 90% at the same time. However, measurement errors between two methods for MC remarkably decreased with a decrease in the MC in a slab. Especially when the MC was maintaining below 60%, the errors between TDR and loadcell methods for measuring MC in the rock-wool slab were less than 5%. There were no significant differences in number of fruits and fresh and dry weights of fruits when they were cultured under the different MC conditions with three irrigation regimes (40%, 50%, and 60%). These results indicated that the MC control by TDR sensors in a rock-wool based paprika culture can be suggested as a method to determine the starting point of irrigation for a soilless culture system.

• KIPS Transactions on Software and Data Engineering
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• v.7 no.2
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• pp.43-50
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• 2018

Biometric information computing is greatly influencing both a computing system and Big-data system based on the bio-information system that combines bio-signal sensors and bio-information processing. Unlike conventional data formats such as text, images, and videos, biometric information is represented by text-based values that give meaning to a bio-signal, important event moments are stored in an image format, a complex data format such as a video format is constructed for data prediction and analysis through time series analysis. Such a complex data structure may be separately requested by text, image, video format depending on characteristics of data required by individual biometric information application services, or may request complex data formats simultaneously depending on the situation. Since previous bio-information processing computing systems depend on conventional computing component, computing structure, and data processing method, they have many inefficiencies in terms of data processing performance, transmission capability, storage efficiency, and system safety. In this study, we propose an improved biosensing converged big data computing architecture to build a platform that supports biometric information processing computing effectively. The proposed architecture effectively supports data storage and transmission efficiency, computing performance, and system stability. And, it can lay the foundation for system implementation and biometric information service optimization optimized for future biometric information computing.

• Membrane Journal
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• v.31 no.2
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• pp.87-100
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• 2021

With a striking increase in the level of contamination and subsequent degradations in the environment, detection and monitoring of contaminants in various sites has become a crucial mission in current society. In this review, we have summarized the current research areas in membrane-based colorimetric sensors for trace detection of various molecules. The researches covered in this summary utilize membranes composed of cellulose fibers as sensing platforms and metal nanoparticles or fluorophores as optical reagents. Displaying decent or excellent sensitivity, most of the developed sensors achieve a significant selectivity in the presence of interfering ions. The physical and chemical properties of cellulose membrane platforms can be customized by changing the synthesis method or type of optical reagent used, allowing a wide range of applications possible. Membrane-based sensors are also portable and have great mechanical properties, which enable on-site detection of contaminants. With such superior qualities, membrane-based sensors examined in the researches were used for versatile purposes including quantification of heavy metals in drinking water, trace detection of toxic antibiotics and heavy metals in environmental water samples. Some of the sensors exhibited additional features like antimicrobial ability and recyclability. Lastly, while most of the sensors aimed for a detection enabled by naked eyes through rapid colour change, many of them investigated further detection methods like fluorescence, UV-vis spectroscopy, and RGB colour intensity.