• Journal of Korean Society on Water Environment
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• v.24 no.6
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• pp.718-724
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• 2008

The ion selective microelectrode (ISME) has been used for measuring the ion profile of DO, $NH_4{^+}-N$, $NO_2{^-}-N$ and $NO_3{^-}-N$ in biofilm. In this study we evaluated the detection limit and validity of ISME and applied ISME for the continuous measurement of $NH_4{^+}-N$ and $NO_3{^-}-N$ concentration in the modified Ludzack-Ettinger (MLE) process. Average detection limits of $NH_4{^+}-N$ and $NO_3{^-}-N$ ISME were $10^{-4.44}M$ and $10^{-4.62}M$, respectively. Since the ISME with $5{\sim}10{\mu}m$ of tip diameter showed a faster response time than that of $1{\sim}5{\mu}m$, the ISME with a tip diameter of $5{\sim}10{\mu}m$ was fabricated and used to make real-time ion detections. Direct monitoring of $NH_4{^+}-N$ and $NO_3{^-}-N$ concentrations in the aerobic (2) tank causes the instability of the electromotive force (EMF) for the initial 5~8 hours and also causes remarkable error values of $NH_4{^+}-N$ and $NO_3{^-}-N$ concentration. This phenomenon is caused by aeration and mixing in the reactor. Thus, the measuring chamber was newly designed for the aerobic (2) tank and then the EMF of the ISME were stabilized in less than 1 hour. Errors of $NH_4{^+}-N$ and $NO_3{^-}-N$ concentration were decreased after stabilization of the EMF. The ISME analysis were well corresponded to the results of auto analyzer and ion chromatography. Consequently, the concentration of $NH_4{^+}-N$ and $NO_3{^-}-N$ could be continuously measured for 178 hours by the ISME.

• Clean Technology
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• v.11 no.2
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• pp.69-74
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• 2005

A metal ion detector with a submicron size electrode was fabricated by field-induced AFM oxidation. The square frame of the mesa pattern was functionalized by APTES for the metal ion detection, and the remaining portion was used as an electrode by the self-assembly of MPTMS for Au metal deposition. The conductance changed with the quantity of adsorbed copper ions, due to electron tunneling between the mobile and surface electrodes. The smaller electrode has a lower limit of detection due to the enhancement in electron tunneling through metal ions that are adsorbed between the conductive-tip (mobile) and the surface (fixed) electrode. This two-electrode system immobilized with different functional groups was successfully used in the selective adsorption and detection of target materials.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.5 no.1
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• pp.3-12
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• 1994

We have proposed the optimum threshold detection(OTD) technique of 16 QAM signal in the Rician fading channel and analyzed its error performance with and without the selective combining(SC) diversity technique. And we compared the error performance of OTD with that of conventional threshold detection(CTD). Having the SC diveresity reception, optimum threshold detection(OTD) technique proposed in this paper provides the performance improvement of 1.8~3.2 [dB] in CNR for fading depth K values ranging from 5 to 30 over CTD when the error rate is $10_5$. From the result of numerical analysis, we know that the proposed OTD technique is superior to CTD technique in the Rician fading channel and adoption of the SC diversity technique with the proposed OTD can be considered as a good countermeasure for the Rician fading.

• Journal of Microbiology and Biotechnology
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• v.11 no.6
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• pp.979-985
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• 2001

A fluorometric detection technique for HDL (High Density Lipoprotein) and LDL (Low Density Lipoprotein) was developed for application in a fiber-optic immunosensor using a protein A Langmuir-Blodgget (LB) film. For the fluorescence immunoassay, antibodies specific to HDL or LDL were imobilied on the protein A LB film, and a fluorescence amplification method was developed to overcome their weak fluorescence. The deposition of protein A using the LB technique was monitored using a surface pressure-are $({\pi}-A)$ curve, and the antibody immobilization of the protein A LB film was experimentally verified. The immobilized antibody was used to separate only HDL and LDL from a sample, then the fluorescence of he separated HDL or LDL was amplified. The amount of LDL or HDL was measured using the developed fiber optic fluorescence detection system. The optical properties resulting from the reaction of HDL or LDL with o-phtaldialdehyde, detection range, response time, and stability of the immunoassay were all investigated. The respective detection ranges for HDL and LDL were sufficient to diagnose the risk of coronary heart disease. The amplification step increased the sensitivity, while selective separation using the immobilized antibody led to linearity in the sensor signal. The regeneration of the antibody-immobilized substrate could produce a stable and reproducible immunosensor.

• Journal of Sensor Science and Technology
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• v.30 no.4
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• pp.229-235
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• 2021

This study presents a simple approach for the assembly of a free-standing conductive electronic nanofilm of single-walled carbon nanotubes (SWNTs) suitable for enzymatic electrochemical biosensors. A large-scale SWNT electronic film was successfully produced by the dialysis of p-Terphenyl-4,4''-dithiol (TPDT)-treated SWNTs. Furthermore, Horseradish peroxidase (HRP) was immobilized on the TPDT-SWNT electronic film, and the enzymatic detection of hydrogen peroxide (H₂O₂) was demonstrated without mediators. The detection of H₂O₂ in the negative potential range (-0.4 V vs. Ag/AgCl) was achieved by direct electron transfer of heme-based enzymes that were immobilized on the TPDT-SWNT electronic film. The SWNT-based biosensor exhibited a wide detection range of H₂O₂ from 10 µM to 10 mM. The HRP-doped SWNT electronic film achieved a high sensitivity of 342 ㎛A/mM·cm² and excellent selectivity against a variety of redox-active interfering substances, such as ascorbic acid, uric acid, and acetaminophen.

• Structural Engineering and Mechanics
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• v.84 no.4
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• pp.489-502
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• 2022

This paper is aimed at developing an optimization-based Finite Element model updating approach for structural damage identification and quantification. A modal flexibility-based error function is introduced, which uses modal assurance criterion to formulate the updating problem as an optimization problem. Because of the inexplicit input/output relationship between the candidate solutions and the error function's output, a robust and efficient optimization algorithm should be employed to evaluate the solution domain and find the global extremum with high speed and accuracy. This paper proposes a new multi-stage Selective Particle Swarm Optimization (SPSO) algorithm to solve the optimization problem. The proposed multi-stage strategy not only fixes the premature convergence of the original Particle Swarm Optimization (PSO) algorithm, but also increases the speed of the search stage and reduces the corresponding computational costs, without changing or adding extra terms to the algorithm's formulation. Solving the introduced objective function with the proposed multi-stage SPSO leads to a smart feedback-wise and self-adjusting damage detection method, which can effectively assess the health of the structural systems. The performance and precision of the proposed method are verified and benchmarked against the original PSO and some of its most popular variants, including SPSO, DPSO, APSO, and MSPSO. For this purpose, two numerical examples of complex civil engineering structures under different damage patterns are studied. Comparative studies are also carried out to evaluate the performance of the proposed method in the presence of measurement errors. Moreover, the robustness and accuracy of the method are validated by assessing the health of a six-story shear-type building structure tested on a shake table. The obtained results introduced the proposed method as an effective and robust damage detection method even if the first few vibration modes are utilized to form the objective function.

• Journal of Sensor Science and Technology
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• v.33 no.5
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• pp.318-325
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• 2024

In this study, we fabricated TiO₂-decorated SnO₂ nanorods (TSNRs) via glancing-angle deposition to achieve highly sensitive and selective CH₃COCH₃ detection. The gas-sensing properties of the TSNRs were systematically investigated, and the optimal sensing performance was achieved at 350℃ by 2-nm-thick TSNRs. When the sensors were exposed to 50 ppm of various gases (CH₃COCH₃, C₂H₅OH, C₅H₈, CH₄, and CO), the 2-nm-thick TSNRs demonstrated a 4.6-fold increase in response (R_a/R_g-1=134) to CH₃COCH₃ compared with bare SnO₂ nanorods (R_a/R_g-1=29.5) and exhibited excellent selectivity. In a high-humid environment (relative humidity = 80%), the 2-nm-thick TSNRs indicated a low theoretical detection limit of ≈5.31 ppb for CH₃COCH₃. These results suggest the significant potential of the proposed sensor for use in Internet-of-Things applications, particularly under extreme environmental conditions.

• BMB Reports
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• v.46 no.5
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• pp.270-275
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• 2013

It is essential to analyze rare mutations in many fields of biomedical research. However, the detection of rare mutations is usually failed due to the interference of predominant wild-type DNA surrounded. Herein we describe a sensitive and facile method of detecting rare point mutation on the basis of allele-specific amplification in emulsion PCR. The identification and selective amplification of rare mutation are accomplished in one-pot reaction. The allele-specific primers coupled on magnetic beads allow the exclusive amplification and enrichment of the mutant amplicons. The productive beads bearing mutant amplicons are subsequently stained with the fluorescent dyes. Thus, the rare point mutations with a percentage as low as 0.1%, can be detected by fluorescent analysis. The relative percentages of mutation among different samples can be roughly accessed by counting the fraction of fluorescent positive beads through flow cytometry.

• Bulletin of the Korean Chemical Society
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• v.34 no.7
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• pp.1985-1989
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• 2013

A simple colorimetric and fluorescent anion sensor 1 based on salicylimine showed a high selectivity and sensitivity for detection of cyanide in aqueous solution. The receptor 1 showed high selectivity toward $CN^-$ ions in a 1:1 stoichiometric manner, which induces a fast color change from colorless to orange and a dramatic enhancement in fluorescence intensity selectively for cyanide anions over other anions. Such selectivity resulted from the nucleophilic addition of $CN^-$ to the carbon atom of an electron-deficient imine group. The sensitivity of the fluorescence-based assay (0.06 ${\mu}M$) is below the 1.9 ${\mu}M$ suggested by the World Health Organization (WHO) as the maximum allowable cyanide concentration in drinking water, capable of being a practical system for the monitoring of $CN^-$ concentrations in aqueous samples.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.1
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• pp.31-37
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• 2009

This paper casts an application of an extended fuzzy integral on the selective extraction of color clusters characterized by a particular color hue from color document images. Despite of the negative role of fuzzy integral, the presented approach attains the detection of the seals through the neighborhood information via the center of area method. The conventional fuzzy integral evaluates the negative aspects of the importance about the items by min operator, which result in the discontinuous parts of seals. In an attempt to cope with the drawback our approach considers the integral aspects via the center of area method, which results in the robustness of the images. Finally, the framework is successfully tested on a data set formed by documents from a real application for the detection.