• Bulletin of the Korean Chemical Society
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• v.26 no.10
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• pp.1560-1564
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• 2005

The influence of cetyltrimethylammonium bromide (CTAB) on the electrochemical behavior of bisphenol A at the carbon paste electrode (CPE) was investigated. CTAB, with a hydrophobic C-H chain, can adsorb at the CPE surface via hydrophobic interaction and then change the electrode/solution interface, and finally affects the electrochemical response of bisphenol A, confirming from the remarkable oxidation peak current enhancement. The electrode process of bisphenol A was examined, and then all the experimental parameters which affects the electrochemical response of bisphenol A, such as pH value of the supporting electrolyte, accumulation potential and time, potential scan rate and the concentration of CTAB, were examined. Finally, a sensitive and simple voltammetric method was developed for the determination of bisphenol A. Under the optimum conditions, the oxidation peak current of bisphenol A varied linearly with its concentration over the range from $2.5\;{\times}\;10^{-8}\;to\;1\;{\times}\;10^{-6}$ mol/L, and the detection limit was found to be $7.5\;{\times}\;10^{-9}$ mol/L. This method was successfully employed to determine bisphenol A in some waste plastic samples.

• Bulletin of the Korean Chemical Society
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• v.27 no.11
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• pp.1780-1784
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• 2006

Cloud point extraction was used to extract mefenamic acid (MF) from human urine, and spectrofluorimetry and spectrophotometry were used to analyze extracted MF. The variables affecting extraction and phase separation, i.e. HCl and Triton X-114 concentration, temperature and time of equilibration, were optimized. Under the experimental conditions used the limit of detection for extraction of 25 mL of sample was 0.006 and 0.045 mg $L^{-1}$, with relative standard deviations of 2.52 and 1.45% (n = 5) for spectrofluorimetric or spectrophotometric methods, respectively. Good recoveries in the range of 95-107% were obtained for spiked samples. The proposed methods were applied to the determination of MF in human urine.

• Analytical Science and Technology
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• v.17 no.4
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• pp.363-367
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• 2004

A simple and convenient digestion method was developed for the determination of heavy metal in polyurethane sample using only nitric acid in open system without heating. This digestion method had prevented loss of volatile elements of Hg and As and reduced the pretreatment time for the sample digestion. The detection limit is lowered over 10 times than that of microwave digestion method. Recoveries in polyurethane material were 108% for As, 96 ~ 99% for Hg, 102 ~ 103% for Cr, 98 ~ 102% for Pb, 86 ~ 90% for Cd, and 90 ~ 93% for Cu.

• Analytical Science and Technology
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• v.7 no.4
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• pp.461-469
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• 1994

Trace vanadium was determined by Adsorptive stripping voltammetry with HMDE in PIPES buffer solution. N-Benzoylphenylhydroxylamine was used as a ligand. The calibration curve of vanadium was linear over the range of $10{\sim}70{\mu}g/L$ on accumulation potential of +0.15V and on accumulation time of 10 sec. The various metal ions did not interfere with the determination of vanadium(V) in this case.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.17 no.4
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• pp.17-24
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• 2009

According to the GPS modernization, L5 is the third civilian GPS signal, broadcasts in a radio band reserved exclusively for aviation safety services. However, as the code length of GPS L5 is ten times longer than that of GPS L1, the acquisition processing time in GPS L5 takes longer than that of L1. This characteristics make the code phase detected initially change and cause the tracking loop to unlock. In order to overcome this problem, this paper proposes L5 acquisition schemes for the rapid code phase re-search and the fine doppler determination. The feasibility of the proposed scheme is demonstrated through the simulation results.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.6
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• pp.52-59
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• 2004

Recently the high speed end-milling processing is demanded the high-precise technique with good surface roughness and rapid time in aircraft, automobile part and molding industry. The working factors of high speed end-milling has an effect on surface roughness of cutting surface. Therefore this study was carried out to analyze the working factors to get the optimum surface roughness by design of experiment. From this study, surface roughness have an much effect according to priority on distance of cut, feed rate, revolution of spindle and depth of cut. By design of experiment, it is effectively represented shape characteristics of surface roughness in high speed end-milling. And determination($R^2$) coefficient of regression equation had a satisfactory reliability of 76.3% and regression equation of surface roughness is made by regression analysis.

• Journal of Preventive Medicine and Public Health
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• v.16 no.1
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• pp.193-198
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• 1983

In the determination of organic solvents in workplaces direct reading tube method have been used in Korea for decades. But this method is less accurate and couldn't measure TWA(Time Weighted Average) for 8 hours. Authors tried to detect Toluene concentration in S factory by using charcoal tube according to NIOSH method. The concentration was 158.8ppm. We propose this charcoal tube method should be substituted to get accurate results and to protect employee in workplaces related with solvents.

• Journal of Korea Multimedia Society
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• v.11 no.6
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• pp.755-763
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• 2008

Silhouette is useful in computer graphics for a number of techniques such as non-photorealistic rendering, silhouette clipping, and blueprint generating. Methods for generating silhouette are classified into three categories: image-based, object-based, and hybrid-based. Hybrid-based method is effective in terms of time complexity but spatial coherence problem still remains. In this paper, we proposed a new hybrid-based method which produces 3D data for silhouette and also guarantees no spatial coherence problem. To verify the efficiency of the proposed algorithm, several experiments are conducted for various 3D models from simple to quite complex. Results show that our algorithm generates no gap between any two consecutive silhouette lines when the silhouette model is magnified significantly.

• Bulletin of the Korean Chemical Society
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• v.15 no.12
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• pp.1035-1037
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• 1994

An ultrasensitive and selective stripping voltammetric scheme for the determination of rhodium is described. By the use of combined accumulation and catalytic effects in formaldehyde-hydrochloric acid medium, substantial improvement in the limit of detection can be obtained. Optimal experimental conditions were found to be 0.42 M hydrochloric acid solution containing 0.008${\%}$ formaldehyde, an accumulation potential of -0.70 V (vs. Ag/AgCl) and an accumulation time of 20 s. The stripping mode was differential pulse voltammetry. In these conditions the limit of detection lies at 2 ${\times}$ l0$^{-12}$ M (0.21 ppt). The relative standard deviation at 5 ${\times}$ l0$^{-11}$ M was 4.9${\%}$ (n=5). There were no serious interferences from other platinum group metal ions being the tolerable amounts more than 500 times that of rhodium.

• Journal of the Korean Chemical Society
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• v.63 no.1
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• pp.45-50
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• 2019

Because arsenic (As) is a chemical substance toxic to humans, there have been extensive investigations on the development of As detection methods. In this study, the electrochemical determination of As on nanoporous gold (NPG) electrodes was investigated using anodic stripping voltammetry. The electrochemical surface area of the NPG electrodes was controlled by changing the reaction times during the anodization of Au for NPG preparation, and its effect on the electrochemical behavior during As detection was examined. The detection efficiency of the NPG electrodes improved as the roughness factor of the NPG electrodes increased up to around 100. A further increase in the surface area of the NPG electrodes resulted in a decrease of the detection efficiency due to high background current levels. The most efficient As detection efficiency was obtained on the NPG electrodes prepared with an anodization time of 50 s. The effects of the detection parameters and of the Cu interference in As detection were investigated and the NPG electrode was compared to flat Au electrodes.