• Membrane Journal
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• v.12 no.4
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• pp.247-254
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• 2002

In order to develop the ion exchange membranes which would be used in direct methanol fuel cell (DMFC), the polysulfone polymer was sulfonated using chlorosulfonic acid (CSA) and trimethylchlorosilane(TMCS). It has been characterized in terms of ion conductivities, methanol crossover, swelling degree and ion exchange capacities for the heat untreated and treated membranes at $150^{\circ}C.$ Typically, the methanol permeability and ion conductivity at the mole ratio of 1.4 between polysulfone repeating unit and sulfonating agents showed $2.87{\times}10^{-7}\; cm^2/s$(without heat treatment), $1.52{\times}10^{-7}\; cm^2/s$(with heat treatment) and $1.10{\times}10^{-2}\; S/cm$(without heat treatment), $0.87{\times}10^{-2}\;$ S/cm(with heat treatment), respectively. After the mole ration of 1.4 both values indicated mild increase.

• Journal of Korean Society of Transportation
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• v.32 no.5
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• pp.522-530
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• 2014

Spatio-temporal congestion evolution pattern can be reproduced using the VDS(Vehicle Detection System) historic speed dataset in the TMC(Traffic Management Center)s. Such dataset provides a pool of spatio-temporally experienced traffic conditions. Traffic flow pattern is known as spatio-temporally recurred, and even non-recurrent congestion caused by incidents has patterns according to the incident conditions. These imply that the information should be useful for traffic prediction and traffic management. Traffic flow predictions are generally performed using black-box approaches such as neural network, genetic algorithm, and etc. Black-box approaches are not designed to provide an explanation of their modeling and reasoning process and not to estimate the benefits and the risks of the implementation of such a solution. TMCs are reluctant to employ the black-box approaches even though there are numerous valuable articles. This research proposes a more readily understandable and intuitively appealing data-driven approach and developes an algorithm for identifying congestion patterns for recurrent and non-recurrent congestion management and information provision.

• YAKHAK HOEJI
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• v.48 no.3
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• pp.207-212
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• 2004

An analytic method was developed for the quantitation of $\Delta$$^{9}-$ tetrahydrocannabinol (THC) and 11-nor-9-carboxy THC (THC-COOH) in human hair. After hair samples were pulverized using Freezer Mill, deuterated internal standards were added and digested in 1 N NaOH at $100^{\circ}C$ water bath for 30 min. Digest solutions were extracted by 5 ml hexane：ethyl acetate (90：10) after acidification with acetic acid. The organic phase was evaporated under N 2 and derivatized by BSTFA (with 1% TMCS) at $85^{\circ}C$ for 45 min. The derivatized solution was separated on HP-5MS column ($30m{\times}0.25mm{\times}0.25mm$) and detected using EI-GC-MS with selective ion monitoring mode. The assay of calibration was ranged from 5 to 100 ng/50 mg hair ($r^2$＞0.99) for THC and THC-COOH. Within and between-run precision were calculated at 6, 30, 60 ng/50 mg hair with coefficients of variation less than 11%. Within and between run accuracies at the same concentrations were$\pm$14% and $\pm$30% of target for both analytes, respectively. Absolute and relative recovery at 10 and 100 ng were 60∼91％. The method was used to detect and quantify THC and THC-COOH in cannabis abuser's hairs (N = 16) and SRM (N=5, THC 1 ng/mg, NIST). We detected THC and THC-COOH in only one hair sample. In SRM, % accuracy was 93% (range 86∼103%) and precision (% CV) was 8.14. We began to set up a quantitative analysis of THC and THC-COOH using EI-GC-MS. Continuously, we need to modify and develop this method in order to apply for identification in cannanbis users' hair.

• Analytical Science and Technology
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• v.28 no.5
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• pp.323-330
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• 2015

Alkaptonuria, a rare inherited metabolic disease, is characterized by a lack of homogentisate dioxygenase and accumulation of homogentisic acid (HGA), leading to homogentisic aciduria, arthritis, and ochronosis. In this study, a rapid analytical method, without an expensive and tedious solid phase extraction step, was developed to quantify HGA in plasma using GC-MS. HGA-spiked pooled plasma samples were subjected to liquid-liquid extraction (LLE) with ethyl acetate, followed by trimethylsilyl derivatization (TMS) and GC-MS quantification using selected ion monitoring. The formation of TMS derivative of the 1 carboxylic and 2 hydroxyl functional groups was performed by reacting BSTFA (with 10% TMCS) for 5 min at 80 ℃. For selected ion monitoring, quantification and confirmation ions were determined based on specific ions (m/z 384, m/z 341 and m/z 252) of the TMS derivative of HGA. Calibration curves of pooled normal plasma specimens showed a linear relationship in the range of 1-100 ng/µL. The precision and accuracy were within a relative standard deviation (RSD) of 1 to 15% and a bias of -5 to 25%. Recoveries were obtained in the range of 99-125% and 95-115% for intra-day and inter-day assay, respectively, at 2, 20 and 80 ng/µL. The limit of detection (LOD) and limit of quantification (LOQ) were 0.4 ng/µL and 4 ng/µL, respectively. No homogentisic acid was excreted from normal Korean plasma samples. Collectively, the results from the present study suggest that this method could be useful for routine diagnosis and therapeutic monitoring of alkaptonuria patients with excellent sensitivity and rapidity.

• Analytical Science and Technology
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• v.11 no.5
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• pp.374-385
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• 1998

Phytoestrogens are biologically active compounds derived from plants foods. It had been suggested that phytoestrogens, by inhibiting aromatase in peripheral and/or cancer cells and lowering estrogen levels, may play a protective role as antipromotional compounds during growth of estrogen-dependent cancers. Therefore, simultaneous analysis of estrogens and phytoestrogens is necessary to elucidate the possible involvement of phytoestrogens in estrogen metabolism. In this view, we developed a simple and reproducible procedure to quantitatively determine estrogen and phytoestrogen metabolites. The proposed method consisted of solid phase extraction using preconditioned Serdolit AD-2 resin, enzyme hydrolysis with ${\beta}$-glucuronidase/arylsulfatase from Helix pomatia, liquid-liquid extraction and TMS-ether derivatization. And the final determination was carried out by gas chromatography/mass spectrometry (GC/MS) in selected ion monitoring mode (SIM). The precision and accuracy of this method was evaluated through within-a-day and day-to-day test. Recovery range and detection limit were 71.96~105.66%, 2~4 ng/mL, respectively. Using this method, 17 estrogen and 5 phytoestrogen compositions in urine of normal subjects were analyzed. It was found that amounts and relative distribution of urinary phytoestrigens and estrogens showed different pattern in male and female subjects.