• Analytical Science and Technology
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• v.16 no.6
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• pp.509-512
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• 2003

Pretreatment method for the determination of total arsenic in seafood sample was studied. NIST SRM 1566a oyster tissue ($14.0{\pm}1.2mg\;As/kg$) as a standard arsenic compound in order to establish the decomposition method. We confirmed that the best way for pretreatment of seafoods to analyze total arsenic content precisely was $HNO_3-H_2SO_4-HCIO_4$ method by comparison of two methods which are dry ashing and wet ashing methods.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.2
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• pp.236-240
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• 2002

Characteristics of ostrich egg shell and optimal ashing conditions for preparation of calcium lactate were investigated. Average weight, girth, and length of ostrich egg shell with membrane (OESM) were 255.17 g, 39.50 cm, and 15.20 cm, respectively. Ostrich egg shell without membrane (OES) contained 0.35% moisture, 40.98% Ca as a maior mineral, 2.43% protein, and 235.0 mg/100 g of amino acids. Optimal ashing times for preparation of white-colored ashing powder from OES were 12 hr at $700^{\circ}C$, 80 min at 80$0^{\circ}C$, and 15 min at 90$0^{\circ}C$, respectively. These ashing conditions resulted in ashing powder with yields of 54.5~54.6% and color values of 97.26 ~97.51 for $L^{*}$, -0.30~-0.34 for $a^{*}$, and 0.63~0.98 for $b^{*}$. Ashing powders, from three different particle size ranges of OES, did not show significant differences in yield.eld.d.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.23 no.4
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• pp.333-340
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• 2013

Objectives: This study was designed to establish an accurate analytical method for asbestos in a biological sample for determining occupational asbestos-related diseases and relief of the health effects of environmental asbestos. Methods: Biological samples were obtained from lungs of rats following intratracheal instillation of asbestos(Chrysotile, anthophyllite) and were prepared according to digestion method(Wet digestion, high temperature ashing, low temperature ashing). The samples were then analyzed for asbestos fibers using a transmission electron microscope equipped with an energy dispersive X-ray spectrometer. Results: Low temperature plasma ashing removed more of the organic components and reduced fiber loss compared to the wet digestion method, making specimens so prepared more suitable for transmission electron microsocpy. Conclusions: The low temperature ashing technique is the most accurate method for analyzing asbestos in biological samples.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.152-155
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• 2003

Ashing of photoresist was investigated in dielectric barrier discharges in atmospheric pressure by changing applied voltage, frequency, flow rate. we analyzed the plasma by Optical Emission Spectroscopy(OES) to monitor the variation of active oxygen species. Another new peaks of oxygen radical is observed by addition of argon gas. This may explain the increase in ashing rate with argon addition. With the results of Optical Emission Spectroscopy(OES), we can find the optimized ashing conditions. MIS capacitor for monitoring charging damage by the plasma was also studied. The results suggest the dielectric barrier discharges(DBD) can be an efficient, alternative Plasma source for general surface processing.

• Transactions on Electrical and Electronic Materials
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• v.7 no.4
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• pp.204-209
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• 2006

Photo Resist (PR) ashing process was carried out with the atmospheric pressure- dielectric barrier discharge (ADBD) using $SF_6/N_2/O_2$. Ashing rate (AR) was sensitive to the mixing ratio of the oxygen and nitrogen of the blower type of ADBD asher. The maximum AR of 5000 A/min was achieved at 2% of oxygen in the $N_2$ plasma. With increasing the oxygen concentration to more than 2% in the $N_2$ plasma, the discharge becomes weak due to the high electron affinity of oxygen, resulting in the decrease of AR. When adding 0.5% of SF6 to $O_2/N_2$ mixed plasma, the PR AR increased drastically to 9000 A/min and the ashed surface of PR was smoother compared to the processed surface without $SF_6$. Carbon Fluorinated polymer may passivate the PR surface. It was also observed that the glass surface was not damaged by the fluorine.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.356-357
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• 2008

The effects of $O_2$ plasma ashing process for surface treatment of nano-wire Bio-FET were investigated. In order to evaluate the plasma damage introduced by $O_2$ plasma ashing, a back-gate biasing method was developed and the electrical characteristics as a function of $O_2$ plasma power were measured. Serious degradations of electrical characteristics of nano-wire Bio-FET were observed when the plasma power is higher than 50 W. For curing the plasma damages, a forming gas anneal (2 %, $H_2/N_2$) was carried out at $400^{\circ}C$. As a result, the electrical characteristics of nano-wire Bio-FET were considerably recovered.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.339-342
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• 1998

Plasma etching of photoresist needs high etch rate, good uniformity and rae, good uniformity and low damage in low cost. ICP asher is expected to satisfy these requriement for next eneration semiconductor devices. ICPsimulator has been used to design the ashing chamber to redcue the development time and cost, and its results have been verified by QMS, OES and langmuir probe measurments. Plasma characteristics are monitored in terms of RF power and chamber pressure.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.7
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• pp.53-62
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• 2003

• Journal of environmental and Sanitary engineering
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• v.16 no.1
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• pp.91-101
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• 2001

In order to propose a optimum method increasing accuracy and reproducibility in analysis of urine lead levels, we compared matrix modifier addition method and microwave digestion method. The results were as follows ; 1. Where the concentration of $Pd(NO_3)_2$(matrix modifier) was $50mg/{\ell}$, and ashing temperature was $900^{\circ}C$, the results were optimum. In case of matrix modifier addition method, the average coefficient of variation (CV) of normal man was 24.1%, and lead worker was 7.9%. The average urine lead levels of standard were $10.42\mu{g}/{\ell}$ and $19.89\mu{g}/{\ell}$ , the accuracies compared to reference values were 97.0% and 92.6%, respectively. 2. Microwave digestion temperature($160~180^{\circ}C$), time(15~25min) and the ratio of urine/ashing acid(1:1~4:1) did not significantly affect lead absorbance and background absorbance. Therefore we set up a optimum analytical conditions as follows: temperature, $160^{\circ}C$; time, 15min; the ratio of urine/ashing acid, 4:1. after samples were digested by the above analytical conditions, lead absorbance and background absorbance was measured at $450^{\circ}C$ as ashing temperature. The average coefficient of variation (CV) of normal man was 12.4%, and lead worker was 6.2%. The average urine lead levels of standard urine were $10.66\mu{g}/{\ell}$ and $23.31\mu{g}/{\ell}$, the accuracies compared to reference values were 99.3% and 103.9%, respectively. From the results, we suggest that microwave digestion method is a more favorable method than matrix modifier addition method because of easiness to reduce organic matter, possibility to analysis at low temperature and accuracy.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.2
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• pp.241-245
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• 2002

To effectively utilize ostrich egg shell as a calcium source, various conditions for preparation of calcium lactate from ashing powder (ashed for 15 min at 90$0^{\circ}C$) were evaluated. Optimal conditions involved treatment of ashing powder with 30 mL lactic acid solution at room temperature for 15 min with a CaO : lactic acid ratio (mol/mol) of 1:2. Calcium lactate contained 39.70% calcium comparable to that (40.98%) in ostrich egg shell. Solubility of calcium lactate, 97.7%, was considerably higher than those (0.58% and 3.43%, respectively) of ostrich egg shell and ashing powder, indicating that the former can be utilized more effectively as a calcium source than the two latter.