• Food Science of Animal Resources
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• v.41 no.1
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• pp.59-70
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• 2021

A method for simultaneous detection of fipronil (F) and its metabolites fipronil desulfinyl (FD), fipronil sulfide (FS), fipronil sulfone (FSO) in chicken eggs was applied and validated. It includes single-step, cheap, effective, rugged, safe-based method (SinChERS) for sample preparation and ultra high performance liquid chromatography coupled with mass spectrometry (UHPLC-MS/MS) for chemical analysis. Results suggested that formic acid enhanced the recovery of 4 target residues and 1% supplementation to acetonitrile gained higher recoveries than that of 5%. SinChERS integrated extraction and clean-up steps into one, with shorter time (1.5 h) to operate and higher recoveries (97%-100%) than HLB, Envi-Carb-NH2 and quik-easy-cheap-effective-rugged-safe method (QuEChERS), and it consumed the smallest volume of extracting solvent (10 mL) as QuEChERS. Quantitative analyses using external standard method suggested the linear ranges of 4 target compounds were 1-20 ㎍/L with R2 >0.9947. The limit of detection (S/N>3) and quantification (S/N>10) were 0.3 ㎍/kg and 1 ㎍/kg. Recoveries ranged from 89.0% to 104.4%, and the relative standard deviations (n=6) at 1, 10, and 20 ㎍/kg were lower than 6.03%. Thirty batches of domestic eggs (500 g each) were detected by the established SinChERS-based UHPLC-MS/MS and no target residues were detected in all samples. The method developed in this study is a rapid, sensitive, accurate and economic way for multi-residue analysis of fipronil and its metabolites in eggs.

• Journal of Sensor Science and Technology
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• v.31 no.3
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• pp.168-174
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• 2022

Hydrogen sulfide(H₂S) gas is a high-risk gas that can cause suffocation or death in severe cases, depending on the concentration of exposure. Various studies to detect this gas are still in progress. In this study, we demonstrate a colorimetric sensor that can detect H₂S gas using its direct color change. The proposed nanofiber sensor containing a dye material named Lead(II) acetate, which changes its color according to H₂S gas reaction, is fabricated by electrospinning. The performance of this sensor is evaluated by measuring RGB changes, ΔE value, and gas selectivity. It has a ΔE value of 5.75 × 10^-3 ΔE/s·ppm, showing improved sensitivity up to 1.4 times that of the existing H₂S color change detection sensor, which is a result of the large surface area of the nanofibers. The selectivity for H₂S gas is confirmed to be an excellent value of almost 70 %.

• Journal of International Society for Simulation Surgery
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• v.2 no.1
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• pp.33-39
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• 2015

Purpose The head of infants under 24 months old who has Craniosynostosis grows extraordinarily that makes head shape unusual. To diagnose the Craniosynostosis, surgeon has to inspect computed tomography(CT) images of the patient in person. It's very time consuming process. Moreover, without a surgeon, it's difficult to diagnose the Craniosynostosis. Therefore, we developed technique which detects Craniosynostosis automatically from the CT volume. Materials and Methods At first, rotation correction is performed to the 3D CT volume for detection of the Craniosynostosis. Then, cranial area is extracted using the iterative thresholding method we proposed. Lastly, we diagnose Craniosynostosis by analyzing centroid relationships of clusters of cranial bone which was divided by cranial suture. Results Using this automatical cranial detection technique, we can diagnose Craniosynostosis correctly. The proposed method resulted in 100% sensitivity and 90% specificity. The method perfectly diagnosed abnormal patients. Conclusion By plugging-in the software on CT machine, it will be able to warn the possibility of Craniosynostosis. It is expected that early treatment of Craniosynostosis would be possible with our proposed algorithm.

• Journal of the Korean Association of Geographic Information Studies
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• v.1 no.1
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• pp.3-7
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• 1998

The issue of data accuracy brings a different perspective to the issue of GIS modeling, calls into a question the usefulness of data models such as DEM. Accuracy can be determined by randomly checking positional and attribute accuracy within a GIS data layer. With the increasing availability of DEM and the software capable of processing them, it is worthwhile to call attention for data accuracy and error analysis as GIS application depends on the priori established spatial data. The purpose of this paper was to investigate methods for data accuracy measurement and error detection methodology with two types of DEM's: 1 to 24,000 and 1 to 250,000 DEM released by U.S. Geological Survey. Another emphasis was given to the development of methodology for processing DEM's to create Arc/Info and GRASS layers. Data accuracy analysis with DEM was applied to a 250 sq.km area and an error was detected at a scale of 1:24,000 DEM. There were two possible reasons for this error: gross errors and blunders.

• Journal of the Korean Vacuum Society
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• v.1 no.1
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• pp.115-120
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• 1992

SIMS is an indispensable surface analysis instrument in trace element depth profiling because of high detection sensitivity and excellent depth resolution, however, it requires a standard sample to do quantitative analysis due to matrix effect depending on the species of impurities and sample matricies and on the sputtering rates. Among the SNMS technology developed to supply the deficiency, we researched into CsX+ SNMS which improved the result quantitatively without any extra epuipments. So basic SNMS functions were confirmed through matrix element composition rate analysis using Siq layer etc., and adaptability to trace element concentration alaysis was tried. For that purpose we compared SIMS depth profile data for Boron which presented strong matrix effect on account of Fluorin existence after BF2 ion implantation on silicon substrate with SNMS data. Also detection limit and dynamic range were investigated. After these experements we concluded that CsX+ SNMS reduced matrix effect and we could apply it to profile impurity elements.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.6
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• pp.555-562
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• 2010

For the rapid and reliable detection of toxic compounds in water, a novel toxicity detection methodology based on sulfur-oxidizing bacteria (SOB) has been developed. The methodology exploits the ability of SOB to oxidize elemental sulfur to sulfuric acid in the presence of oxygen. The reaction results in an increase in electrical conductivity (EC) and a decrease in pH. Using a synthetic stream water (EC=0.12 mS/cm and pH=7.2), the baseline steady-state EC and pH values were 0.5~1.2 mS/cm and ~2.5 over 7 days of testing at HRT 30 minutes. When nitrite compounds were added to the system, the effluent EC decreased and the pH increased due to the inhibition of the SOB. Optimum HRT was 30 min and this HRT could be decresed by using smaller sulfur particles.

• Bulletin of the Korean Chemical Society
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• v.28 no.3
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• pp.373-378
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• 2007

A micro organism Agrobacterium tumifacient as an immobilized cell on a solid support was presented as a new biosorbent in a simple and sensitive spectrophotometry determination of Ni(II) in various samples using 4-hydroxy benzaldehyde-4-bromophenyl hydrazone as a color developing agent (λmax 497 nm) at pH 4.0 ± 0.2. Beer's law was obeyed over the range of 0.01-0.1 μg L-1. The molar absorptivity and Sandell's sensitivity were 1.285 × 105 L mol-1cm-1 and 0.007245 μg cm-2 respectively. Under these conditions, the preconcentration factor obtained was 82, and the detection limit achieved was 0.05 μg L-1. The detailed study of various interfering ions made the method more sensitive and selective. The recovery of Ni(II) from various samples range from 97.75 to 99.35%. The present method was successfully applied for the determination of Ni(II) in spiked, natural water and alloy samples. The proposed method was compared with reported methods in terms of Student's ‘t'-test and Variance ratio ‘f'-test which indicates that there is no significant difference between proposed and literature method at 95% confidence level.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.1
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• pp.68-79
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• 1998

In this paper, we propose a model-based FDI(fault detetion and isolation) algorithm to detect and isolate fault in a linear system. The proposed algorithm is gased on an HFC(hydrid fault classifier) which consists of an FCART2(fault classifier by ART2 neural network) and an FCFM(fault classifier by fault models) which operate in parallel to isolate faults. The proposed algorithm is functionally composed of three main parts-parameter estimation, fault detection, and isolation. When a change in the system occurs, the estimated parameters go through a transition zone in which errors between the system output and the stimated output and the estimated output cross a predetermined thrseshold, and in this zone the estimated parameters are tranferred to the FCART2 for fault isolation. On the other hand, once a fault in the system is detected, the FCFM statistically isolates the fault by using the error between ach fault model out put and the system output. From the computer simulation resutls, it is verified that the proposed model-based FDI algorithm can be performed successfully to detect and isolate faults in a position control system of a DC motor.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.2
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• pp.891-894
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• 2014

This study is aimed to investigate the role of paired boxed gene 1 (PAX1) methylation analysis by methylation-sensitive high-resolution melting (MS-HRM) in the detection of high grade lesions in atypical squamous cells cannot exclude high-grade squamous intraepithelial lesion (ASC-H) and compared its performance with the Hybrid Capture 2 (HC2) human papillomavirus (HPV) test. In our study, 130 cases with a diagnosis of ASC-H from the cervical cytological screening by Thinprep cytologic test (TCT) technique were selected for triage. Their cervical scrapings were collected and evaluated by using PAX1 methylation analysis (MS-HRM) and high-risk HPV DNA test (HC2), followed by colposcopy and cervical biopsy. Chi-square test were used to test the differences of PAX1 methylation or HPV infection between groups. In the detection of CIN2+, the sensitivity, specificity, the PPV, NPV and the accuracy of PAX1 MS-HRM assay and high-risk HPV (HR-HPV) tests were respectively 80.6% vs 67.7%, 94.9% vs 54.5%, 83.3%, vs 31.8%, 94.0% vs 84.4%, and 91.5% vs 57.7%. The PAX1 MS-HRM assay proved superior to HR-HPV testing in the detection of high grade lesions (CIN2+) in ASC-H. This approach could screen out the majority of high grade lesion cases of ASC-H, and thus could reduce the referral rate to colposcopy.

• Analytical Science and Technology
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• v.28 no.2
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• pp.112-116
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• 2015

Extraction of quaternary ammonium compounds (choline and betaine) from plant samples (spinach) using ion exchange resin (AG1, OH⁻ form) is a very simple and inexpensive approach. However, it is very hard to determine amounts of choline and betaine simultaneously using high-performance liquid chromatography-ultraviolet (HPLC-UV) detection. Unlike choline, betaine has low molar absorptivity in UV-visible (UV-Vis) region, which makes it difficult to carry out UV-Vis detection of betaine. The mixture of quaternary ammonium compounds (choline and betaine) was derivatized using 2-bromo acetophenone as a derivatizing agent. As a result, choline did not react with the derivatizing agent, whereas betaine formed a betaine derivative. This betaine derivative exhibited detectable UV absorption with baseline separation between choline and the betaine derivative. Thus, with this method, choline and betaine can be determined simultaneously by using the HPLCUV method through one-step derivatization, which is an easy, sensitive, and reliable method.