• Analytical Science and Technology
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• v.25 no.3
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• pp.190-196
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• 2012

The human exposure of lead has usually detected the amount of lead in the whole blood, however, this method has a shortcoming to give the information on the short-term exposure to lead. In that sense, it is desirable to estimates the level of lead in plasma to draw the chronic bio-marker of lead exposure even though it is difficult to measure lead of several ng/L. An inductively coupled plasma-mass spectrometry (ICP-MS) method was developed for determining lead in plasma as the chronic bio-marker of lead of workers. To minimize the contamination of lead from the environment, we constructed class 1,000 clean room and compared the amount of floating dust before and after the operation of the clean room. The limit of detection (LOD) and the limit of quantification (LOQ) of lead in fetal bovine serum were 4.3 ng/L and 12.2 ng/L by NIOSH method (statistical calculation method) and 7.0 ng/L and 22.1 ng/L by signal/noise ratio, respectively. The accuracy was in a range of 92.3-101.3%, and the precision of the assay was less than 4% in the samples spiked in the concentration of 20 ng/L and 2,000 ng/L. The method was simple, reproducible and sensitive enough to permit reliable analysis of lead to the ng/L level in plasma and/or serum. The method was also useful for the biological monitoring of chronic exposure to lead.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.10
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• pp.1038-1045
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• 2006

A series of experiments was conducted to test the compatibilities of two different techniques to determine elemental concentrations by INAA and ICP-MS based on both the NIST SRM 2783(air particulate on filter media) and the field samples for PM10. For NIST SRM the results of INAA were more accurate and precise for all target elements than those of ICP-MS. The comparative data set for PM10 samples collected in an industrial complex area showed that mean of concentration ratio, derived for the two different methods such as C(INNA/ICP-MS), were distinguished from each other: (1) Ba, Cu, K Mg, Na, and Sb: $0.9{\sim}1.1$; (2) Al, Co, Fe, and Mn: $0.8{\sim}1.2$; and (3) Se, Ti, and Zn: >1.3. When the results obtained from both methods were evaluated in terms of regression analysis, paired t-test, and Wilcoxon signed-rank test, the results of many elements determined from PM10 samples(such as Al, Ba, Co, Cu, Fe, K, Mn, Nd, and Sb) exhibited a fairly good agreement between the two methods, despite a wide range of variation.

• Analytical Science and Technology
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• v.24 no.1
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• pp.38-44
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• 2011

The quality of decoction water would be important for the preparation of herbal medicines. Four types of decoction water, S1, S2, S3 and S4, three types of mineral water from Jeju island and one type of tap water from Seoul region were evaluated. The contents of minerals in decoction water were analysed by ICP-AES and ICP-MS. There was significant difference in the mineral contents between the types of decoction water. The bioactive components from rhubarb were extracted with four types of water and the relationship between mineral contents in water and the extracted amounts of components was evaluated. The total extraction was calculated by evaporating water and weighing the residue. The bioactive components in rhubarb were determined by HPLC method. Kruskall-Wallis rank sum tests were used. Multiple factor analysis was used to analyze the relation between the contents of mineral and total extraction or bioactive components in the decocted solutions. Not only the total extraction but also the amount of extracted bioactive components showed statistically significant relationship with the contents of minerals and anions in decoction water.

• Resources Recycling
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• v.26 no.4
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• pp.50-55
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• 2017

Determination of trace elements in a sample including complicated matrix is very difficult due to the interference by the matrix. Therefore, if the trace elements can be separated from the complex sample matrix and determined, the interference effects can be reduced, and it is very helpful for the overall analysis. In this study, the analytes of trace elements were separated from the sample matrix by co-precipitation with trace elements using indium hydroxide ($In(OH)_3$), then detected by inductively coupled plasma-atomic emission spectrometer (ICP-AES). Above all, the optimal conditions for the co-precipitation of elements with indium hydroxide were experimentally established. At last, salt was analyzed by the developed analytical method. No heavy metals were not found in Shinan Jeungdo salt, but trace amounts of several heavy metals except for cadmium were found in Cheonnam Yongkwang salt.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.404-404
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• 2016

태양전지 제작 시 표면에 피라미드 구조를 형성하면 입사되는 광의 흡수를 높여 광 생성 전류의 향상에 기여한다. 일반적인 KOH를 이용한 습식 표면조직화 공정은 평균 10%의 반사율을 보였으며, 유도 결합 플라즈마를 이용한 RIE 공정은 평균 5.4%의 더 낮은 반사율을 보였다. 그러나 RIE 공정을 이용한 표면조직화는 낮은 반사율과 서브 마이크론 크기의 표면 구조를 만들 수 있지만 플라즈마 조사에 의한 표면 손상이 많이 발생하게 된다. 이러한 표면 손상은 태양전지 제작 시 표면에서 높은 재결합 영역으로 작용하게 되어 포화 전류(saturation currents, $J_0$)를 증가시키고 캐리어 수명(carrier lifetime, ${\tau}$)을 낮추는 결함 요소로 작용한다. 이러한 플라즈마에 의한 표면 손상을 제거하기 위해 HF, HNO3, DI-water를 이용하여 DRE(Damage Remove Etching) 공정을 진행하였다. DRE 공정은 HF : DI-water 솔루션과 HNO3 : HF : DI-water 솔루션의 두 가지 공정을 이용하여 공정 시간을 가변하며 진행하였다. 포화전류($J_0$), 캐리어 수명(${\tau}$), 벌크 캐리어 수명(Bulk ${\tau}$)을 비교를 하기위해 KOH, RIE, RIE + DRE 공정을 진행한 세 가지 샘플로 실험을 진행하였다. DRE 공정을 적용할 경우 공정 시간이 지날수록 반사도가 높아지는 경향을 보였지만, 두 번째의 최적화된 솔루션 공정에서 $2.36E-13A/cm^2$, $42{\mu}s$의 $J_0$, Bulk ${\tau}$값과 가장 높은 $26.4{\mu}s$의 ${\tau}$를 얻을 수 있었다. 이러한 결과는 오제 재결합(auger recombination)이 가장 많이 발생하는 지역인 표면과 불균일한 도핑 영역에서 DRE 공정을 통해 나아진 표면 특성과 균일한 도핑 프로파일을 형성하게 되어 재결합 영역과 $J_0$가 감소 된 것으로 판단된다. 높아진 반사도의 경우 $SiN_x$를 이용한 반사방지막을 통해 표면 반사율을 1% 이내로 내릴 수 있어 보완이 가능하였다. 본 연구에서는 RIE 공정 중 플라즈마에 의해 발생하는 표면 손상 제거를 통하여 캐리어 라이프 타임의 향상된 조건을 찾기 위한 연구를 진행하였으며, 기존 RIE 공정에 비해 반사도의 상승은 있지만 플라즈마로 인한 표면 손상을 제거하여 오제 재결합에 의한 발생하는 $J_0$를 낮출 수 있었고 높은 ${\tau}$값인 $26.4{\mu}s$의 결과를 얻어 추후 태양전지 제작에 향상된 효율을 기대할 수 있을 것으로 기대된다.

• Korean Chemical Engineering Research
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• v.46 no.3
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• pp.619-625
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• 2008

The effects of thermal cycling on residual stresses in both inorganic passivation/insulating layer that is deposited by plasma enhanced chemical vapor deposition (PECVD) and organic thin film that is used as a bonding adhesive are evaluated by 4 point bending method and wafer curvature method. $SiO_2/SiN_x$ and BCB (Benzocyclobutene) are used as inorganic and organic layers, respectively. A model about the effect of thermal cycling on residual stress and bond strength (Strain energy release rate), $G_c$, at the interface between inorganic thin film and organic adhesive is developed. In thermal cycling experiments conducted between $25^{\circ}C$ and either $350^{\circ}C$ or $400^{\circ}C$, $G_c$ at the interface between BCB and PECVD $ SiN_x $ decreases after the first cycle. This trend in $G_c$ agreed well with the prediction based on our model that the increase in residual tensile stress within the $SiN_x$ layer after thermal cycling leads to the decrease in $G_c$. This result is compared with that obtained for the interface between BCB and PECVD $SiO_2$, where the relaxation in residual compressive stress within the $SiO_2$ induces an increase in $G_c$. These opposite trends in $G_cs$ of the structures including either PECVD $ SiN_x $ or PECVD $SiO_2$ are caused by reactions in the hydrogen-bonded chemical structure of the PECVD layers, followed by desorption of water.

• Applied Chemistry for Engineering
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• v.26 no.3
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• pp.372-376
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• 2015

6-MQCC (Cr(VI)-6-methylquinoline) complex was synthesized by the reaction of 6-methylquinoline with chromium(VI) trioxide in 6 M HCl. The structure was characterized using IR (Infrared Spectroscopy) and ICP (Inductively Coupled Plasma) analysis. The oxidation of benzyl alcohol using 6-MQCC in various solvents showed that the reactivity increased with the increase of the dielectric constant, in descending order of DMF > acetone > chloroform > cyclohexene. In the presence of DMF solvent with acidic catalyst such as sulfuric acid ($H_2SO_4$), 6-MQCC oxidized benzyl alcohol (H) and its derivatives ($p-OCH_3$, $m-CH_3$, $m-OCH_3$, m-Cl, $m-NO_2$) were effectively oxidized. Electron-donating substituents accelerated the reaction rate, whereas electron acceptor groups retarded the reaction rate. The Hammett reaction constant (${\rho}$) was -0.69 (308 K). The observed experimental data was used to rationalize the fact that the hydride ion transfer occurred at the rate-determining step.

• Applied Chemistry for Engineering
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• v.27 no.1
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• pp.110-114
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• 2016

Cr(VI)-pyrazine complex (PZCC) was synthesized by the reaction of pyrazine with chromium (VI) trioxide in 6 M HCl. The structure was characterized using IR spectroscopy and inductively coupled plasma (ICP). The oxidation of benzyl alcohol using PZCC in various solvents showed that the reactivity increased with the increase of the dielectric constant, in the order: N,N'-dimethylform-amide > acetone > chloroform > cyclohexene. In the presence of N,N'-dimethylformamide solvent with an acidic catalyst such as sulfuric acid ($H_2SO_4$ solution), PZCC oxidized benzyl alcohol (H) and its derivatives ($p-OCH_3$, $m-CH_3$, $m-OCH_3$, m-Cl, $m-NO_2$). Electron-donating substituents accelerated the reaction rate, whereas electron acceptor groups retarded the reaction rate. Hammett reaction constant (${\rho}$) was -0.70 (308 K). The observed experimental data were used to rationalize the hydride ion transfer in the rate-determining step.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.11
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• pp.6039-6046
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• 2013

Cr(VI)-heterocyclic complex[Cr(VI)-2-methylpyrazine] was synthesized by the reaction between of heterocyclic compound(2-methylpyrazine) and chromium trioxide, and characterized by IR and ICP analysis. The oxidation of benzyl alcohol using Cr(VI)-2-methylpyrazine in various solvents showed that the reactivity increased with the increase of the dielectric constant(${\varepsilon}$), in the order : cyclohexene${\rho}$) was Cr(VI)-2-methylpyrazine= -0.65(308K). The observed experimental data have been ratiolized. The hydride ion transfer causes the prior formation of a chromate ester in the rate-determining step.

• Applied Chemistry for Engineering
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• v.25 no.6
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• pp.648-653
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• 2014

Cr(VI)-heterocyclic complex (2,4'-bipyridinium chlorochromate) was synthesized by the reaction between heterocyclic compound(2,4'-bipyridine) and chromium trioxide, and characterized by IR and ICP analysis. The oxidation of benzyl alcohol using 2,4'-bipyridinium chlorochromate in various solvents showed that the reactivity increased with the increase of the dielectric constant (${\varepsilon}$), in the order : N,N-dimet-hylformamide (DMF) > acetone > chloroform > cyclohexene. In the presence of DMF solvent with acidic catalyst such as hydrochloric acid (HCl solution), 2,4'-bipyridinium chlorochromate oxidized benzyl alcohol (H) and its derivatives (p-$CH_3$, m-Br, m-$NO_2$). Electron-donating substituents accelerated the reaction rate, whereas electron acceptor groups retarded the reaction rate. The Hammett reaction constant (${\rho}$) was -0.67 (303 K). The observed experimental data have been rationalize the proton transfer occurred followed the formation of a chromate ester in the rate-determining step.