• Applied Chemistry for Engineering
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• v.10 no.3
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• pp.445-449
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• 1999

Hydrophilic polyphosphazenes were synthesized from hydrophobic polyphosphazenes by adding methoxyethylenoxy side chains and cast by dip-coating method into membranes supported on porous polypropylene mesh filter sheet for metal separation testing. A solution of $Cr^{3+},\;Co^{2+},\;Mn^{2+}$ nitrates was used in diffusion experiments which were conducted from $25^{\circ}C$ to $60^{\circ}C$. lt was found that the ion transport properties were increased as the repeating number of ethylenoxy side chain increased. Membrane from trifluoroethoxy methoxyethoxyethoxyethoxy co-substituted polyphosphazenes was found to separate $Cr^{3+}$ ion from $Mn^{2-}$ and $Co^{2+}$ ions with separation factor of 4.5 at $60^{\circ}C$.

• Korean Journal of Materials Research
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• v.5 no.5
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• pp.503-511
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• 1995

금속/실리콘계에 대한 이온선 혼합시의 비정질상 및 결정상 형성여부를 예측할 수 있는 모델(ADF Model)과초기 결정상 예측 모델(PDF Model)의 적용을 실험적으로 조사하기 위하여 Ni/Si계에 대한 이온선 혼합을 온도와 이온선량을 변수로 하여 행하였으며 상형ㅅㅇ과정을 해석하였다. 이온선 혼합은 80keV가속기를 이용하여 상온~20$0^{\circ}C$의 온도 범위에서 1.0 $\times$ $10^{15}$Ar^{+}$/$cm^{2}$~2.0 $\times$ $10^{-16}$Ar^{+}$/$cm^{2}$의 이온선량을 변화시키면서 실험하였고, 상분석은 TEM과 GXRD를 이용하였다. Ni/Si게에 대한 ADF값은 0.804로 양의 값을 가지므로 이온선 혼합시 비정실상이 형성되고, $Ni_{2}$Si상이 다른 화합물상보다 훨씬 큰 음의 PDF값을 갖으므로 초기 결정상이 $Ni_{2}$Si가 될 것을 예측하였다. 이러한 예측은 실험결과와 매우 잘 일치하였다. 이상의 연구결과로부터 ADF 및 PDF모델을 이용하여 박막에서 형성되는 상을 보다 정확히 예측할수 잇음을 알 수 있었다.

• Journal of the Korean Chemical Society
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• v.43 no.4
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• pp.430-437
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• 1999

The determination of total chlorine residuals in drinking water by flow injection analysis(FIA) with iodometric UV detection was investigated. The pH of the acid stream, the concentration of the iodide ion,the length of the mixing and reaction coils, the injection sample size, and flowrate were optimized as parameters for determining total chlorine residuals by FIA method. lodide was selectively oxidized to iodine by hypochlorite at pH 8.3 Ethylenediamine as masking agent for masking interference ions from the sample was given the best efficency. Calibration curve presented linear range of 0.03-3 mg/L for hypochlorite ion with a correlation coefficient of 0.999 or better. The detection limit was found to be 0.007 mg/L for hypochlorite ion. Under these analytical conditions, total chlorine residuals in several tap water sampled in the city of Jeonju were analyzed.

• Journal of the Korean Chemical Society
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• v.28 no.2
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• pp.121-129
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• 1984

The adsorption characteristics of heavy metal ions $(Ni^{2+}$, $Zn^{2+}$) on domestic activated carbon which manufactured from the wood, waste rubber and coal has been studied. The following conclusions were obtained by investigating the effect of pH, halides, cyanide and temperature on the absorption of heavy metal ions and by determining absorption rate and absorption isotherms. When heavy metal ions were adsorbed on activated carbon in the pH range from 6 to 7, treated heavy metal ions were almost come to the equilibrium and recovered in the form of complex anions such as $MX_4^{2- }$and $M(CN)_4^{2-}$ in an hour. The absorption isotherms of heavy matel ions were well fitted in Freundlich's equation. Heavy metal complex anions on activated carbon were easily eluted by using 0.1N HCl solution. These results suggest that the complex anions have unexpectedly strong affinity for the surface of activated carbon.

• Journal of the Korean Chemical Society
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• v.51 no.4
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• pp.324-330
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• 2007

A new ion selective PVC membrane electrode is developed as a sensor for mercury(II) ions based on bis(benzoylacetone) propylenediimine (H2(BA)2PD) as an ionophore. The electrode shows good response characteristics and displays, a linear Emf vs. log[Hg2+] response over the concentration range of 1.0×10-6 to 1.0×10-1 M Hg(II) with a Nernstian slope of 29.8±0.75 mV per decade and with a detection limit of 2.2×10-7 M Hg(II) over the pH range of 2.5-11.5. Selectivity concentrations for Hg(II) relative to a number of potential interfering ions were also investigated. The sensor is highly selective for Hg(II) ions over a large number of cations with different charge. The sensor has been found to be chemically inert showing a fast response time of 60 s and was used over a period of 3 months with a good reproducibility (S = 0.27 mV). The electrode was successfully applied to determine mercury(II) in real samples with satisfactory results.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.95-95
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• 2013

박막 공정 기술은 반도체 및 디스플레이뿐만 아니라 대부분의 전자소자에 적용되는 매우 중요한 기술이다. 그 중, 마그네트론 스퍼터링 공정은 플라즈마를 이용하여 금속 및 세라믹 등의 벌크 물질을 박막으로 증착 가능한 가장 널리 사용되는 방법 중의 하나이다. 하지만, Fe, Co, Ni 같은 강자성체 재료는 공정이 불가능하며, 스퍼터링 타겟 효율이 40% 이하이고, 제한적인 방전압력 범위 및 전류 상승에 의한 높은 전압 인가 제한이 있다는 단점이 있다. 본 연구에서 사용된 고밀도 플라즈마 소스를 적용한 고효율 스퍼터링 시스템은 할로우 음극을 이용한 원거리에서 고밀도 플라즈마를 생성하여 전자석 코일을 통해 자석이 없는 음극으로 이온을 수송시켜 스퍼터링을 일으킨다. 따라서 강자성체 재료의 스퍼터링이 가능하며, 90% 이상의 타겟 사용 효율 구현 및 기존 마그네트론 스퍼터링 대비 고속 증착이 가능하다. 또한, $10^{-4}$ Torr 압력영역에서 방전 및 스퍼터링이 가능하다. 타겟 이온 전류를 타겟 인가 전압과 관계없이 0~4 A까지, 타겟 이온 전류와 상관없이 타겟 인가 전압을 70~1,000 V 이상까지 독립적으로 제어가능하다. 또한 TiN과 같은 질소 반응성 공정에서 반응성 가스인 질소를 40%까지 넣어도 타겟에 수송되는 이온의 양에 영향이 없다. 할로우 음극 방전 전류 40 A에서 발생된 플라즈마의 이온에너지 분포는 55 eV에서 가우시안 분포를 보였으며, 플라즈마 포텐셜인 sheath drop은 74 V 였다. OES를 통한 광학적 진단 결과, 전자석에 의한 이온빔 초점에 따라 플라즈마 이온화율을 1.8배까지 증가시킬 수 있으며, 할로우 음극 방전 전류가 60~100 A로 증가하면서 플라즈마 이온화율을 6배까지 증가 가능하다. 또한, 타겟 이온 전류와 관계없이 타겟 인가 전압을 300~800 V로 증가시킴에 따라 Ar 이온 밀도의 경우 1.4배 증가, Ti 이온 밀도의 경우 2.2배 증가시킬 수 있었으며, TiN의 경우 증착 속도도 16~44 nm/min으로 제어가 가능하다.

• Membrane Journal
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• v.8 no.3
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• pp.148-156
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• 1998

Diffusion dialysis is a membrane process driven by concentration difference using ion-exchange membranes and has been employed for many years for the acid recovery from acidic waste generated in steel, metal-refining and dectro-plating industries. Theoretically acid flux increases in propomon to the acid concentration difference. At acid concentrations higher than 3 N HCl, however, the acid flux had not increased linearly with the concentration difference. In this paper the effects of acid concentrations on diffusion dialysis for hydrochloric acid recovery and the acid transport mechanism in an anion exchange membrane were studied by membrane sorption tests and diffusion clialysis cell tests. The experimental results showed that the molecular diffusion was a major transport mechanism in a low acid concentration range and the proton leakage through an anion exchange membrane played an important role at higher acid concentrations. Also osmotic water transport and membrane dehydration retarded the transport of protons and caused the permeate flux to decrease.

• Analytical Science and Technology
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• v.7 no.3
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• pp.261-269
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• 1994

The iodide formed stoichiometrically for sulfide by its oxidation with iodate was extracted as an ion-pair with methylene green into 1,2-dichloroethane and the extract was measured spectrophotometrically at 656nm for the determination of sulfide. Hydrogen sulfide separated from the sample matrix was introduced into a solution containing pH 3.5 acetate buffer and iodate, in which the hydrogen sulfide was completely converted into iodide. A linear calibration graph was obtained over the range $3{\times}10^{-7}{\sim}1.2{\times}10^{-5}M$ sulfide($0.0096{\sim}0.384{\mu}g$ of $S^{2-}/ml$) and the detection limit was $0.0032{\mu}g/ml$. The apparent molar absorptivity and a correlation coefficient(r) were $6.7{\times}10^4L\;mole^{-1}\;cm^{-1}$ and 0.999, respectively. When applied to the stream water samples, the proposed method gave a relative standard deviation of 1.59% at $5{\times}10^{-6}M$ sulfide level.

• Nuclear Engineering and Technology
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• v.23 no.4
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• pp.426-437
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• 1991

The $He^{++}$ beam transport system of the SNU 1.5-MV Tandem Van de Graaff accelerator is analysed by ion optical approach. The program OPTRANS is developed to determine the optimum operating conditions of each ion optical component and to simulate ion beam transport. First order matrix formalism is used and the space charge effect is neglected. Optimum operating conditions for the transport of 0.5~3.0 MeV $He^{++}$ beam are determined by the use of the program OPTRANS. Initial ion beam omittance is assumed to be 0.5$\times$80.0 mm.mrad from the structure of the extraction electrode and the experiment of ion beam extraction. ion beam transport characteristics of each ion optical component according to the variation of the operating conditions are investigated, and operating conditions to minimize the beam size at each slit, stripping foil, and target are calculated. Optimum operating conditions obtained from the experiment of ion beam transport show a discrepancy of less than 15% compared with the calculated ones. From the simulation and experiment of ion beam trans-port, the validity of the calculated optimum operating conditions and the usefulness of the program OPTRANS are verified.

• Journal of the Korean Chemical Society
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• v.44 no.6
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• pp.541-546
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• 2000

Methods to determine L-dopa(L-3,4-dihydroxyphenylalanine) in aqueous solution by spectrofluorimetry based upon the ligand sensitized luminescence of Tb(III) ion L-dopa complex have been studied. Tb(III) ion and Lu(III) ion were used as ligand sensitized fluorescencer and co-fluorescence enhancer, respectively. The effects of excitation wavelength, pH, concentration of Tb(III) ion, concentration of Lu(III) ion and emission wavelength on the fluorescence intensity were investigated. The fluorescence intensity of the Tb(III) ion L-dopa complex was further increased with addition of Lu(III) ion. The calibration curve for L-dopa was linear over the range from 5.0 ${\times}$ $10^{-7}$ M to 1.0${\times}$ $10^{-4}$ M and the detection limit was 4.0 ${\times}$ $10^{-8}$ M under the optimal experimental conditions of 300 nm, 8.0, 1.0 ${\times}$ $10^{-4}$ M and 545 nm for excitation wavelength, pH, concentration of Tb(III) ion and emission wavelength, respectively. When Lu(III) ion was added to Tb(Ⅲ) ion L-dopa complex, the concentration range of linear response and detection limit were 1.0${\times}$$10^{-8}$ M to 2.0 ${\times}$ $10^{-4}$ M and 1.0 ${\times}$ $10^{-9}$ M, respectively under the optimal experimental conditions of 300 nm, 8.5, 1.0 ${\times}$ $10^{-5}$ M, 1.0 ${\times}$ $10^{-5}$ M, 545 nm for excitation wavelength, pH, concentration of Tb(III) ion, concentration of Lu(III) ion and emission wavelength, respectively.