• Progress in Superconductivity
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• v.7 no.1
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• pp.28-35
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• 2005

We propose a method to measure atrial arrhythmias (AA) such as atrial fibrillation (Afb) and atrial flutter (Afl) with a SQUID magnetocardiograph (MCG) system. To detect AA is one of challenging topics in MCG. As the AA generally have irregular rhythm and atrio-ventricular conduction, the MCG signal cannot be improved by QRS averaging; therefore a SQUID MCG system having a high SNR is required to measure informative atrial excitation with a single scan. In the case of Afb, diminished f waves are much smaller than normal P waves because the sources are usually located on the posterior wall of the heart. In this study, we utilize an MCG system measuring tangential field components, which is known to be more sensitive to a deeper current source. The average noise spectral density of the whole system in a magnetic shielded room was $10\;fT/{\surd}Hz(a)\;1\;Hz\;and\;5\;fT/{\surd}Hz\;(a)\;100\;Hz$. We measured the MCG signals of patients with chronic Afb and Afl. Before the AA measurement, the comparison between the measurements in supine and prone positions for P waves has been conducted and the experiment gave a result that the supine position is more suitable to measure the atrial excitation. Therefore, the AA was measured in subject's supine position. Clinical potential of AA measurement in MCG is to find an aspect of a reentry circuit and to localize the abnormal stimulation noninvasively. To give useful information about the abnormal excitation, we have developed a method, separative synthetic aperture magnetometry (sSAM). The basic idea of sSAM is to visualize current source distribution corresponding to the atrial excitation, which are separated from the ventricular excitation and the Gaussian sensor noises. By using sSAM, we localized the source of an Afl successfully.

• Korean Journal of Psychosomatic Medicine
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• v.21 no.2
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• pp.140-146
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• 2013

Objectives: We compared the characteristics of the pain threshold and pain experience between demented group and non-demented group. Methods: This study was part of Gangwon projects for early detection of dementia in 2010. We recruited 8302 local resident ages over 65 years old. Of theses, 1259 people who scored low MMSE were selected and 365 of them completed CERAD-K(Consortium to Establish a Registry for Alzheimer's disease). Finally, 90 in non-demented group and 57 in demented group(mild to moderate Alzheimer's disease) were analyzed. Pain threshold was experimentally measured by pressure algometer and we investigated the pain experience, by Brief pain inventory (BPI), a self-report test. Results: In the demographic characteristics, there are more female, higher ages, lower education in the demented group. There was no significant difference between the two groups in the pain threshold. On the BPI results, 'shoulder pain', 'the number of pain' and 'interference of working' were significantly more prevalent in non-demented group. However, there are no significant differences between the groups in the 'pain severity', 'prevalence of pain' and 'pain treatment'. Conclusions: Demented group report less pain experience but, still perceived pain. It support previous studies that patient with dementia have increased pain tolerance but preserved pain threshold. Thus, active pain assessment and treatment for patients with dementia is needed.

• Analytical Science and Technology
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• v.23 no.3
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• pp.240-246
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• 2010

A technique for the determination of trace Cu(II) in various real samples by FAAS after the column preconcentration onto p-dichlorobenzene-SA adsorbent, which is microcrystalline p-dichlorobenzene loaded with salicylaldoxime (SA) has been developed. Several experimental conditions such as pH of the sample solution, the amount of chelating agent salicylaldoxime, the amount of adsorbent p-dichlorobenzene-SA, and flow rate of sample solution were optimized. The interfering effects of various concomitant ions were investigated. $CN^-$ interfered more seriously than any other ions. However, the interference by $1\;{\mu}g\;mL^{-1}\;CN^-$ could be overcome completely by controlling the concentration of Ni(II) to $20\;{\mu}g\;mL^{-1}$. The linear range, correlation coefficient ($R^2$) and detection limit obtained by this technique were $3.0\sim100\;ng\;mL^{-1}$, 0.9901, and $3.1\;ng\;mL^{-1}$, respectively. For validating this technique, the aqueous samples (wastewater, reservoir water and stream water) and the food samples (orange juice, fresh egg and skim milk) were used. Recovery yields of 93~104% were obtained. These measured mean values were not differents from ICP-MS data at 95% confidence level. The good results were obtained from the experiments using the rice flour certified reference material (CRM) sample. Based on the experimental results, it was found that this technique could be applied to the preconcentration and determination of Cu(II) for various real samples.

• Korean Journal of Food Science and Technology
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• v.42 no.4
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• pp.390-397
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• 2010

Residual solvents in foods are defined as organic volatile chemicals used or produced in manufacturing of extracts or additives, or functional foods. The solvents are not completely eliminated by practical manufacturing techniques and they also may become contaminated by solvents from packing, transportation or storage in warehouses. Because residual solvents have no nutritional value but may be hazardous to human health, there is a need to remove them from the final products or reduce their amounts to below acceptable levels. The purpose of this study was to develop and evaluate an analytical method for the screening of residual solvents in health functional foods. Furthermore, the aim of this study was to constitute a reasonable management system based on the current state of the market and case studies of foreign countries. Eleven volatile solvents such as MeOH, EtOH, trichloroethylene and hexane were separated depending on their column properties, temp. and time using Gas Chromatography (GC). After determining the GC conditions, a sample preparation method using HSS (Head Space Sampling) was developed. From the results, a method for analyzing residual solvents in health functional foods was developed considering matrix effect and interference from the sample obtained from the solution of solvents-free health functional foods spiked with 11 standards solutions. Validation test using the developed GC/HSS/MS (Mass Spectrometry) method was followed by tests for precision, accuracy, recovery, linearity and adequate sensitivity. Finally, examination of 104 samples grouped in suits was performed by the developed HSS/GC/MS for screening the solvents. The 11 solvents were isolated from health functional foods based on vapor pressure difference, and followed by separation within 15 minutes in a single run. The limt of detection (LOD), limit of quantification (LOQ), recovery and coefficient of variation (C.V.) of these compounds determined by the HSS/GC/MS were found to be 0.1 pg/mL, 0.1-125 pg/g, 51.0-104.6%, and less than 15%, respectively. Using the developed HSS/GC/MS method, residual solvent from 16 out of 104 health functional products were detected as a EtOH. This method therefore seems t o be a valuable extension ofanalytical method for the identification of residual solvents in health functional food.

• Journal of Pharmaceutical Investigation
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• v.40 no.2
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• pp.101-107
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• 2010

A rapid and sensitive reversed-phase high performance liquid chromatography (HPLC) method was developed for the determination of N-(-4-Chlorophenyl)-6-hydroxy-7-methoxy-2-chromanecarboxamide (KAL-1120), a novel anti-inflammation agent, in the rat plasma. The method was applied to analyze the compound in the biological fluids such as bile, urine and tissue homogenates. After liquid-liquid extraction, the compound was analyzed on an HPLC system with ultraviolet detection at 275 nm. HPLC was carried out using reversed-phase isocratic elution with a $C_{18}$ column, a mobile phase of a mixture of acetonitril (40 v/v%) at a flow rate of 1.0 mL/min. The chromatograms showed good resolution and sensitivity and no interference of plasma. The calibration curve for the drug in plasma was linear over the concentration range of 0.05-50 ${\mu}g$/mL. The intra- and inter-day assay accuracies of this method ranged from 0.06% to 9.33% of normal values and the precision did not exceed 6.28% of relative standard deviation. The plasma concentration of KAL-1120 decreased to below the quantifiable limit at 1.5 hr after the i.v. bolus administration of 2-10 mg/kg to rats ($t_{1/2,({\alpha})}$ and $t_{1/2,({\beta})$ of 2.15 and 26.7 min at a dose of 2 mg/kg, 3.91 and 33.0 min at a dose of 10 mg/kg, respectively). The steady-state volume of distribution ($V_{dss}$) and the total body clearance ($CL_t$) were not significantly altered in rats given doses from 2 to 10 mg/kg. Of the various tissues tested, KAL-1120 was mainly distributed in the lung and heart after i.v. bolus administration. KAL-1120 was detected in the bile by 30 min after its i.v. bolus administration. However, the concentration in the urine after i.v. bolus administration became too low to measure, suggesting that KAL-1120 is mostly excreted in the bile. In conclusion, this analytical method was suitable for the preclinical pharmacokinetic studies of KAL-1120 in rats.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.5
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• pp.128-134
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• 2014

Recently, design and construction of street tunnels tend to focus on cost reduction and preservation of nature. Accordingly, research is actively being carried out to quickly detect fires when they occur in tunnels, which have partially closed structures. Among such research, fire detection methods using optical fiber sensors have a wide bandwidth and fast transmission speed, while using light as a medium. Therefore, it does not receive electrical interference and there is almost no loss of information during transmission, while also having little noise as well. In relation to this, a fire monitoring system that can accurately detect the location of fires in real time using shape memory alloy and optical cables was developed in this study. In order to verify the developed method, light loss measurement test was conducted according to indoor temperature changes, while also conducting fire simulation tests by installing test beds in common underground zones with different external environments of temperature and distance. Upon carrying out experiments, the fire monitoring system developed in this study was found to be able to detect fires in long distance sections in real time.

• Journal of the Korean Chemical Society
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• v.43 no.4
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• pp.423-429
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• 1999

A spectrofluorimetric method for the determination of Fe(III) in aqueous solution with 4,5-dihydroxy-1,3-benzenedisulfonic acid(Tiron) as a fluorimetric reporter was developed. Tiron, which is very soluble in water,is a good fluorimetric reagent. However, when Tiron was complexed with Fe(III), the fluorescent intensity was decreased proportionally with the concentration of Fe(III) by a quenching effect. The excitation and fluorescene wavelength of Tiron showing the quenching effect by Fe(III) at pH 4.5 were 312 nm and 341 nm, respectively. The highest sensitivities were shown at Tiron concentration of $1.0{\times}10^{-2}M$. To enhance the quenching effect, the Fe(III)-Tiron complex solution was heated to 80$^{\circ}C$ for 90 minutes. As for Fe(III), the most interfering ion was Cu(II). The interference effects could be mostly eliminated by pH adjustment or by adding EDTA. The concentration ranges showing the linear response to Fe(III) was from $5.0{\times}10^{-7}M\;to\;6.0{\times}10^{-5}M$ With this proposed method, the detection limits of Fe(III) was $2.8{\times}10^{-6}M$. Recovery of Fe(lII) in a synthetic sample was almost quantitative. Based on experimental results, it is proposed that the above technique can be applied to the practical determination of Fe(III).

• Journal of the Korean Chemical Society
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• v.37 no.10
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• pp.881-887
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• 1993

A cobalt(II) ion-selective carbon-paste electrode (CPE) was constructed with ${\iota}$-sparteine. Cobalt(II) ion in aqueous solution was chemically deposited through the complexation with ${\iota}$-sparteine onto the CPE. The surface of CPEs were characterized by cyclic voltammetry and differential pulse voltammetry in an acetate buffer solution, separately. Exposure of the CPEs to an acid solution could regenerate surface to reuse it for the deposition. In more than 5 deposition / measurement / regeneration cycles, the response was reproducible and linear up to $5.0{\times}10^{-6}$M with linear sweep voltammetry. The peaks at 0.17V / 0.27V were correspond to the redox of Co(II)-SP complex deposited on CPE. The anodic peak of which appeared after scan over the cathodic peak of 0.17 V to more negative scan. In case of using the differencial pulse voltammetry (DPV), we have obtained the linear response $2.0{\times}10^{-7}$M with relative standard deviation ${\pm}5.6%$. The detection limit was $1.0{times}10^{-7}$M for 20 minutes of the deposition. We have also investigated the interference effect of various metal ions, which are expected to form the complex with the ligand on the electrode.

• Journal of the Korean Chemical Society
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• v.40 no.5
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• pp.341-346
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• 1996

Electrochemical determination of iodide was carried out by stripping voltammetry with a $(Cin)Cu(NO_3)_2$ modified-carbon paste electrode. Iodide was coordinated onto the electrode surface containing $(Cin)Cu(NO_3)_2$ via ion exchange. The oxidation peak potential of incorporated iodide was ＋0.72 V. The optimum analytical conditions for the determination of iodide were investigated using linear sweep voltammetry. Optimum conditions for the electrochemical determination of iodide were as follows: i) A predeposition solution was 0.1 M $KNO_3.$ ii) The deposition time was 10 min. iii) The composition of the electrode was 40% (w/w). The detection limit for iodide was $1.0{\times}10^{-6}M$ and the relative standard deviation was ${\pm}5.5%\;in\;2.0{\times}10^{-5}M$(four repetitions). The interference effect of other anions were also investigated. $Cl^-,\;Br^-,\;C_2O_4^{2-},\;and\;ClO_4^-$ ions do not interfere for the determination of iodide. When $SCN^-$ was added to the deposition solution, the oxidation peak current of iodide ion was decreased roughly 32%.

• Journal of the Korean Electrochemical Society
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• v.19 no.2
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• pp.29-38
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• 2016

Screen printed carbon electrodes (SPCEs) with immobilized osmium-based hydrogel redox polymer, uricase and PEGDGE can be used to apply uric acid electrochemical detecting. The osmium redox complexes were synthesized by the coordinating pyridine group having different functional group at 4-position with osmium compounds. The synthesized poly-osmium hydrogel complexes are described as PAA-PVI-$[Os(dCl-bpy)_2Cl]^{+/2+}$, PAA-PVI-$[Os(dme-bpy)_2Cl]^{+/2+}$, PAA-PVI-$[Os(dmo-bpy)_2Cl]^{+/2+}$. The different concentrations of uric acid were measured by cyclic voltammetry technique using enzyme-immobilized SPCEs. The prepared SPCEs using PAA-PVI-$[Os(dme-bpy)_2Cl]^{+/2+}$ showed no interference from common physiologic interferents such as ascorbic acid (AA) or glucose. The resulting electrical currents at 0.33 V vs. Ag/AgCl displayed a good linear response with uric acid concentrations from 1.0 to 5.0 mM. Therefore, this approach allowed the development of a simple, point of care in the medical field, disposable electrochemical uric acid biosensor.