• 분석과학
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• 제16권3호
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• pp.240-248
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• 2003

공업지역에서 악취원인물질로 잘 알려진 황화물은 매우 낮은 최소 후각감지농도를 나타낸다. 여러 악취발생원 주변의 대기 중 미량의 황화합물을 아르곤에서 농축시켜 선택성과 감도가 우수한 불꽃 광도 검출기 (FPD)가 장착된 가스크로마토그래프를 이용하여 측정하였다. 25% ${\beta}$,${\beta}$-Oxydipropionitrile, 60/80 Chromosob W가 저온농축을 위한 흡착제로 되었으며 이를 충전 유리컬럼의 충전제로도 사용하였다. 악취시료의 농축량은 0.1~3.0L 범위에서 채취장소에 따라 달리하였다. 주거지역과 사업장 부지경계선상에서의 공기 및 하수처리장과 같은 공업지역 내 사업장의 배출구 가스 중의 휘발성 황화합물의 농도를 측정하였다.

• 한국환경과학회지
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• 제18권6호
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• pp.645-654
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• 2009

Lab-scale Electrodialysis(ED) system with different membranes combined with before or after pyroma process were carried out to remove nitrate from two pickling acid wastewater containing high concentrations of $NO_3\;^-$(${\approx}$150,000 mg/L) and F($({\approx}$ 160,000 mg/L) and some heavy metals(Fe, Ti, and Cr). The ED system before Pyroma process(Sample A) was not successful in $NO_3\;^-$ removal due to cation membrane fouling by the heavy metals, whereas, in the ED system after Pyroma process(Sample B), about 98% of nitrate was removed because of relatively low $NO_3\;^-$ concentration (about 30,000 mg/L) and no heavy metals. Mono-selective membranes(CIMS/ACS) in ED system have no selectivity for nitrate compared to divalent-selective membranes(CMX/AMX). The operation time for nitrate removal time decreased with increasing the applied voltage from 10V to 15V with no difference in the nitrate removal rate between both voltages. Nitrate adsorption of a strong-base anion exchange resin of $Cl\;^-$ type was also conducted. The Freundlich model($R^2$ > 0.996) was fitted better than Langmuir mode($R^2$ > 0.984) to the adsorption data. The maximum adsorption capacity ($Q^0$) was 492 mg/g for Sample A and 111 mg/g for Sample B due to the difference in initial nitrate concentrations between the two wastewater samples. In the regeneration of ion exchange resins, the nitrate removal rate in the pickling acid wastewater decreased as the adsorption step was repeated because certain amount of adsorbed $NO_3\;^-$ remained in the resins in spite of several desorption steps for regeneration. In conclusion, the optimum system configuration to treat pickling acid wastewater from stainless-steel industry is the multi-processes of the Pyroma-Electrodialysis-Ion exchange.

• 한국환경과학회지
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• 제8권4호
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• pp.491-496
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• 1999

Removal of Cu(II), Cr(III) and Pb(II) ions from aqueous solutions using the adsorption process on the loesses has been investigated. Variations of contact time, pH, adsorption isotherms and selectivity of coexisting ions were experimental parameters. pH of KJ and YIK samples diluted to 1% solution, was rearly the same with each value of pH 5.58 and 5.49, and both samples showed weak acidic properties. From chemical analysis, both samples contain remarkably different amounts of ${SiO}_{2}$, ${Al}_{2}O_{3}$ and ${Fe}_{2}O_{3}$. From XRD measurement, quartz was mainly observed in both samples. Kaolinite was also observed, also in both samples, but Feldspar was only observed in KJ sample. Adsorption of metal ions on the loesses were reached at equilibrium by shaking for about 30min. The adsorption of Cr(III) ion was higher than that of Cu(II) oand Pb(II) ions. The order of amount adsorbed among the investigated ions was Cr(III)>Pb(II)>Cu(II). In acidic solution, the adsorptivity of loesses was increased as pH increased. The adsorption of Cr(III) ion on the loesses were fitted to the Freundlich isotherms. Freundlich constants(1/n) of KJ and YIK loesses were 0.54 and 0.55, respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.174-174
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• 2010

In this article, the dry etching mechanism of ZnO thin films in $N_2/Cl_2$/Ar gas chemistry was investigated. The ZnO thin films were deposited on Si substrate using Atomic layer deposition. The etching experiments were performed by inductively coupled plasma system. The maximum etch rate was104.5 nm/min and the highest selectivity of ZnO over $SiO_2$ was 3.3. Etching rate was measured by surface profiler. And the chemical reaction on the surface of the etched ZnO thin films was investigated by x-ray photo electrons pectroscopy. As a result of XPS, $Zn2p_{3/2}$ peak shifted toward a higher binding energy and the O-O and N-O bond were obtained from the sample of ZnO thin film which after plasma treatment.

• 한국진공학회:학술대회논문집
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• 한국진공학회 1999년도 제17회 학술발표회 논문개요집
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• pp.244-244
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• 1999

Liquid Crystal Displays(LCDs) 투명성 전도막으로 사용하는 Indium Tin Oxide (ITO)의 고밀도 식각특성을 조사하였다. 특히 ITO식각의 경우, pixel electrode 전극에서 사용되는 underlayer인 SiO2, Si3N4와의 최적의 선택비를 얻는데 중점을 두고 있다. 따라서 본 실험에서는 Inductively Coupled Plasma(ICP)를 이용하여 source power, gas combination, bias voltage, pressure 및 기판온도에 따른 ITO의 식각 특성과 이의 underlayer인 SiO2, Si3N4와의 선택비를 조사하였다. Ar과 CH4를 주된 식각가스로서 사용하였으며 첨가가스로는 O2와 HBr를 사용하였다. ITO의 식각특성을 이해하기 위하여 Quadruple Mass Spectrometry(QMS), Optical emission spectroscopy(OES) 이용하였으며, 식각된 sample의 잔류물을 조사하기 위하여 X-ray photoelectron spectroscopy(XPS)를 이용하여 분석하였다. Ar gas에 적정량의 CH4 혼합이 순수한 Ar 가스로 식각한 경우에 비하여 ITO와 SiO2, Si3N4의 선택비가 높았으며, 더 높은 식각 선택비를 얻기 위하여 Ar/CH 분위기에서 첨가가스 O2, HBr을 사용하였다. Source power 및 bias 증가에 따라 ITO의 식각률은 증가하나, underlayer와의 선택비는 감소함을 보였다. 본 실험에서 측정된 ITO의 high 식각률은 약 1500$\AA$/min이며, SiO2, Si3N4와의 high selectivity는 각각 7:1, 12:1로 나타났다. ITO의 etchrate 및 선택비는 source power, bias, pressure, CH 가스첨가에 의존하였지만 기판온도에는 큰 변화가 없음을 관찰하였다. 또한 적정량의 가스조합으로 식각된 시편의 잔류물을 줄일 수 있었다.

• Fisheries and Aquatic Sciences
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• 제18권2호
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• pp.221-227
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• 2015

We analyzed the small-scale purse-seine gear that is used along the North Coast of Java, Indonesia, using computer-aided tools to modify the gear. Data from the middle position of the leadline showed that the maximum depth reached by the net was 30 m. A similar result was also calculated. According to the calculated result, the mean sinking speed of the current gear at the middle position of the leadline was 0.13 m/s, and the maximum tension during pursing was 1,794 kgf. The best sinking performance was found in modified gear that used a 30.3 mm mesh knotless polyester net. The maximum depth reached by the net was 38 m, and mean sinking speed was 0.16 m/s at the middle position of the leadline. The maximum tension during pursing was 1,044 kgf. Independent sample t-test results show that the mean sinking depth and sinking speed in the simulated and measured results did not differ (P > 0.05). These results are expected to improve the efficiency and selectivity of small-scale purse seine gear.

• Bulletin of the Korean Chemical Society
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• 제34권4호
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• pp.1065-1069
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• 2013

A highly sensitive electrochemical detection method for bisphenol A (BPA) has been developed by using multi-walled carbon nanotube (CNT)-doped titania-Nafion composite modified glassy carbon (GC) electrode. The CNT-titania-Nafion/GC electrode exhibited excellent electrocatalytic activity towards BPA. Therefore, the CNT-titania-Nafion/GC electrode showed improved voltammetric responses for BPA compared to that obtained with bare GC electrode. In addition, cetyltrimethylammonium bromide (CTAB), a cationic surfactant, was added into the BPA sample solution in order to accumulate BPA through hydrophobic interaction between CTAB and BPA. The CNT-titania-Nafion/GC electrode gave a linear response ($r^2$ = 0.999) for BPA from $1.0{\times}10^{-8}$ M to $5.0{\times}10^{-6}$ M with a detection limit of $9.0{\times}10^{-10}$ M (S/N = 3). The modified electrode showed good selectivity against interfering species and also exhibited good reproducibility. The present electrochemical sensor based on the CNT-titania-Nafion/GC electrode was applied to the determination of BPA in food package samples.

• 약학회지
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• 제36권5호
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• pp.506-511
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• 1992

The Prostaglandins were derivatized rapidly with monodansyl cadaverine as a fluorophore in mild conditions. The carboxylic moiety of prostaglandins was activated with diethyl phosphorocyanidate and successively coupled with fluorophore in dimethylformamide at room temperature. The labeling yield was reached about 95% at 15 min using arachidic acid $(C_{20:0})$ as a test sample. This derivative showed constant fluorescent intensity at $4^{\circ}C$ for 180 days. The derivatives of prostaglandins were shown high solvent selectivity with tetrahydrofuran in reversed-phase column. therefore, these derivatives could be successfully separated on YMC pack A-212(S-5 120A C8) column in tetrahydrofuran-based eluents. The detection limits of these derivatives was ca. 500 fmol and determination limits was ca. 5 pmol as injected amount in fluorescent detection $({\lambda}ex.\;340\;nm,\;{\lambda}em.\;520\;nm)$. In this method, the ranges of recovery and coefficient of variation were $93.6{\sim}102.7%$ and $4.3{\sim}5.8%$, respectively.

• Bulletin of the Korean Chemical Society
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• 제24권1호
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• pp.37-44
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• 2003

We examined the effect of polyether-type nonionic surfactants (Brij 35, Triton X-100, Tween 20 and Tween 80) on the potentiometric properties of sodium-, potassium- and calcium-selective membranes which are prepared with widely used ionophores and four kinds of polymer matrices [poly(vinyl chloride) (PVC), polyurethane (PU), PVC/PU blend, and silicone rubber (SR)]. It was found that the PVC-based membranes, which provide the best performance among all other matrix-based membranes in the absence of nonionic surfactants, exhibited larger change in their potentiometric properties when nonionic surfactants are added to the sample solution. On the other hand, the sodium-selective SR-based membrane with calix[4]arene, potassium-selective PVC/PU- or SR-based membrane with valinomycin, and the calcium-selective SR-based membrane with ETH 1001 provide almost identical analytical performance in the presence and absence of Tween 20 or Tween 80 surfactants. The origin of nonionic surfactants effect was also investigated by interpreting the experimental results obtained with various matrices and ionophores. The results suggest that the nonionic surfactant extracted into the membrane phase unselectively form complexes with the primary and interfering ions, resulting in increased background potential and lower binding ability for the ionophore. Such effects should result in deteriorated detection limits, reduced response slopes and lower selectivity for the primary ions.

• Food Science and Biotechnology
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• 제18권3호
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• pp.579-585
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• 2009

Solid-phase microextraction (SPME) has gained widespread acceptance in sample pretreatment due to its solvent-free and easy-to-operate properties. SPME fibers are considered as a key part of SPME technique, since it primarily determines the extraction performance of the method including sensitivity, selectivity, and reproducibility. Generally speaking, target analyte with different chemical property requires fiber coating that has the best affinity towards it. Due to the lack of varieties of commercial fibers available currently, considerable efforts have been recently made to develop tailor-made fibers to fulfill increasing demands of different analysis. This paper concisely classify some SPME fiber preparation approaches such as sol-gel technology, physical deposition, molecularly imprinted technique, and their respective application in food safety analysis.