• Analytical Science and Technology
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• v.12 no.2
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• pp.99-104
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• 1999

A stepwise gradient elution with two wavelengths detection was performed for the separation and determination of some anions in saline water. The eight anions such as iodate, bromate, nitrite, bromide, nitrate, chromate, iodide and thiocyanate were successfully separated using AS-7 column and sodium chloride/sodium phosphate buffer solution as an eluant within 40 min. The separation behaviors of anions were studied at various sodium chloride concentrations. The peak shapes of anions of bromate, nitrite, bromide and nitrate gradually broadened as the concentration of sodium chloride increased until 1.0 M in the sample solutions. However, no effect was observed in the peak shapes of chromate, iodide and thiocynate. A good linearity was obtained at the range of ppm(mg/L). The detection limit was proved to be $10-720{\mu}g/L$ for the eight anions with $50{\mu}L$ injection volume. This method was applied to the determination of $Br^-$, ${NO_3}^-$ and $I^-$ in sea water.

• Journal of fish pathology
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• v.9 no.1
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• pp.41-51
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• 1996

The present study was undertaken to investigate the physiological characteristics of the adrenergic responses in the tilapia dorsal aorta. Epinephrine, norepinephrine, clonidine and methoxamine in the presence of propranolol($3{\times}10^{-6}$M), induced only endothelium-independent and concentration-dependent vasocontractions in tilapia dorsal aorta. The rank order of potency of adrenergic agonists inducing vasocontraction was epinephrine>norepinephrine>phenylephrine>clonidine>ethoxamine, Yohimbine produced a parallel shift of the concentration-vascontraction curves of epinephrine, norepinephrine, phenylephrine and clonidine to the right, while prazosin depressed the maximum responses of epinephrine and norepinephrine. Calcium-free physiological solution and verapamil markedly reduced epinephrine or norepinephrine-induced vasocontractions. These results suggest that a-adrenergic agonists produce only on endothelium-inedpenent casoconstrictions in tilapia dorsal aorta and these effect of a-adrenergic agonists, which might be associated with both calcium release from intracellular stores and calcium influx through voltage-dependent calcium channel.

• Journal of the Korean Chemical Society
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• v.21 no.4
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• pp.276-283
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• 1977

Reduction of dichromate at a platinum cathode in acid solution was studied by cyclic voltammetry and controlled potential electrolysis. Cathodic polarization curve consisted of three waves in unbuffered solution of potassium dichromate having initial pH ranges 1.5∼4.0, with sodium sulfate as the supporting electrolyte. Relative heights of the first and the second waves were, respectively, a function of chromium (Ⅵ) concentration and activity of hydrogen ion, but that of the third wave was not proportional to both of them. The current of the first two peaks were proportional to the sweep rate of potential (${\nu}$), while that of the last peak vs. ${\nu}^{1/2}$ was linear at the sweep rate of less than 50mV/sec. By the controlled potential electrolysis, the reduction of chromium (Ⅵ) was almost completely suppressed at potentials more negative than the last peak and at initial pH's above ca. 2.3 of unbuffered solution. Therefore, these peaks represented, respectively, $Cr_2O_7^{2-}{\to}Cr^{3+},\;2H^+{\to}H_2$ and the formation of a cathodic film.

• Journal of the Earthquake Engineering Society of Korea
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• v.7 no.3
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• pp.17-22
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• 2003

This paper presents an experimental investigation of a reversible colloidal seismic damper, which is statically loaded, The porous matrix is composed from silica gel (labyrinth or central-cavity architecture), coated by organo-silicones substances, in order to achieve a hydrophobic surface. Water is considered as associated lyophobic liquid. Reversible colloidal damper static test rig and the measuring technique of the static hysteresis are described. Influence of the pare and particle diameters, particle architecture and length of the grafted molecule upon the reversible colloidal damper hysteresis is investigated, for distinctive types and mixtures of porous matrices, Variation of the reversible colloidal damper dissipated energy and efficiency with temperature, pressure, is illustrated.

• Journal of the Korean Vacuum Society
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• v.9 no.4
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• pp.406-410
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• 2000

Using the hot-wall epitaxy method, we grew a $Hg_{1-x}Cd_xTe$ (MCT) thin film in-situ after growing (111) CdTe of 9 $mu \textrm{m}$ as a buffer layer. The value of FWHM of double crystal x-ray diffraction rocking curve was 125 arcsec and the surface morphology was clean with a small roughness of 10 nm. From measuring the photocurrent of the grown MCT thin film, the maximum peak wavelength and the cut-off wavelength were 1.1050 $\mu\textrm{m}$ (1.1220 eV) and 1.2632 $\mu\textrm{m}$ (0.9815 eV), respectively. This peak wavelength corresponds to the peak of the band gap due to the intrinsic transition of the photoconductor. Therefore, the MCT thin film could be used as the photoconducting detector sensing a near-IR wavelength band from 1.0 to 1.6 $\mu\textrm{m}$.

• Analytical Science and Technology
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• v.6 no.1
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• pp.57-63
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• 1993

Spectrophotometric determination of cobalt by flow injection method is described. 2-(5-Bromo-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino) aniline rapidly forms a water-soluble complex with cobalt in $NH_3-NH_4Cl$ buffer solution at pH 10.5. The absorption maxima of this complex is at 545 nm with molar absorptivity of $58000L\;mol^{-1}\;cm^{-1}$. The calibration curve of cobalt is linear over the range of 0.1 to 0.6ppm and the detection limit is 25ppb. The relative standard deviation is ${\pm}0.72%$ for 0.5ppm and the sampling rate is $60samples\;hr^{-1}$. The interfering effect of some cations and anions was investigated. Ni(II), Cu(II), Fe(III) and $CN^-$ interfered severely. The interfering effect of these matallic ions could be decreased by adding $1.0{\times}10^{-3}M$ EDTA solution to the carrier stream.

• Analytical Science and Technology
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• v.8 no.3
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• pp.285-292
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• 1995

Uranium has variable oxidation states(${UO_2}^{+2}$, $UO^{+2}$, $U^{+4}$, $U^{+3}$) and 1-(2-Pyridylazo)-2-naphthol forms a very stable chelate with Uranium(${UO_2}^{+2}$). The determination method of Uranium(${UO_2}^{+2}$) in 0.1M Borate buffer(pH 7.10) has been investigated by adsorptive stripping voltammetry. The optimum conditions were PAN concentration of $5{\times}10^{-7}M$, accumulation potential of 0.00V(vs. Ag/AgCl) and accumulation time of 120sec. The calibration curve was linear over the range of $5{\sim}60{\mu}g/L$ and the various metal ions did not interfere with the determination Uranium(${UO_2}^{+2}$) except Cu(II) and Co(II).

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.103-103
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• 1999

CeO2 는 cubic 구조의 일종인 CeF2 구조를 가지며 격자 상수가 0.541nm로 Si의 격자 상수 0.543nm와 거의 비슷하여 Si과의 부정합도가 0.35%에 불과하여 CeO2를 Si 기판 위에 에피택셜하게 성장시킬 수 있는 가능성이 크다. 따라서 SOI(Silicon-On-Insulator) 구조의 실현을 위하여 Si 기판위에 CeO2를 에피택셜하게 성장시키려는 많은 노력이 있었다. 또한 CeO2 는 열 적으로 대단히 안정된 물질로서 금속/강유전체/반도체 전계효과 트랜지스터(MFSFET : metal-ferroelectric-semiconductor field effect transistor)에서 ferroelectric 박막과 Si 기판사이에 완충층으로 사용되어 강유전체의 구성 원자와 Si 원자들간의 상호 확산을 방지함으로써 경계면의 특성을 향상시기키 위해 사용된다. e-beam evaporation와 laser ablation에 의한 Si 기판 위의 CeO2 격자 성장에 관한 많은 보고서가 있다. 이 방법들은 대규모 생산 공정에서 사용하기 어려운 반면 RF-magnetron sputtering은 대규모 반도체 공정에 널리 쓰인다. Sputtering에 의한 Si 기판위의 CeO2 막의 성장에 관한 보고서의 수는 매우 적다. 이 논문에서는 Ce target을 사용한 reactive rf-magnetron sputtering에 의해 Si(100) 과 Si(111) 기판위에 성장된 CeO2 의 구조 및 전기적 특성을 보고하고자 한다. 주요한 증착 변수인 증착 power와 증착온도, Seed Layer Time이 성장막의 결정성에 미치는 영향을 XRD(X-Ray Diffractometry) 분석과 TED(Transmission Electron Diffration) 분석에 의해 연구하였고 CeO2 /Si 구조의 C-V(capacitance-voltage)특성을 분석함으로써 증차된 CeO2 막과 실리콘 기판과의 계면 특성을 연구하였다. CeO2 와 Si 사이의 계면을 TEM 측정에 의해 분석하였고, Ce와 O의 화학적 조성비를 RBS에 의해 측정하였다. Si(100) 기판위에 증착된 CeO2 는 $600^{\circ}C$ 낮은 증착률에서 seed layer를 하지 않은 조건에서 CeO2 (200) 방향으로 우선 성장하였으며, Si(111) 기판 위의 CeO2 박막은 40$0^{\circ}C$ 높은 증착률에서 seed layer를 2분이상 한 조건에서 CeO2 (111) 방향으로 우선 성장하였다. TEM 분석에서 CeO2 와 Si 기판사이에서 계면에서 얇은 SiO2층이 형성되었으며, TED 분석은 Si(100) 과 Si(111) 위에 증착한 CeO2 박막이 각각 우선 방향성을 가진 다결정임을 보여주었다. C-V 곡선에서 나타난 Hysteresis는 CeO2 박막과 Si 사이의 결함때문이라고 사료된다.

• Analytical Science and Technology
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• v.7 no.4
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• pp.435-440
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• 1994

Qualitative and quantitative analysis for the anionic surfactants used in the metal washing fluid (brand names are BFA and BCA) was performed by the capillary electrophoresis. Acetonitrile and sodium benzoate were mixed with the buffer solution which controlled at pH 10. Under the 18kV applied voltage, the electropherograms have shown the theoretical plates more than $10^4$. Determined as the concentration at the S/N~3, the typical detection limit was ~5 ppm and the calibration curves have shown the correlation coefficients higher than ~0.99. Based on these results, it was concluded that each components were octanoate, decanoate, dodecanoate, tetradecanoate, hexadecanoate and the relative ratio was 1.0 : 1.0 : 6.5 : 2.1 : 0.8 for the BFA.

• Journal of Korean Society of Transportation
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• v.20 no.7
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• pp.87-94
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• 2002

2001년 경찰청 $\ulcorner$2001년판 교통사고통계$\lrcorner$ 자료에 의하면 사고피해의 정도를 나타내는 치사율에 있어서 중앙선침범사고가 과속사고와 함께 가장 높은 수치를 보이고 있으며, 대형 교통사고의 39.5%가 중앙선 침범에 의해 발생한 것으로 나타났다. 실제로 2000년 한 해 동안 총 사고건수 290,481건 중 중앙선 침범에 의해 18,931건 (6.52%)의 교통사고가 발생하여 사망자 1,472명, 부상자 35,046명으로 전체 교통사고 사망자의 14.38%, 부상자의 8.21%를 점하고 있는 것으로 나타났다. 이와 같이 전체 교통사고에서 중앙선침범사고가 차지하는 비중 이 높아지고 있어 중앙선침범사고를 줄이기 위한 대책의 일환으로 중앙분리대, 표지병, 시선 유도봉 등과 같은 중앙선침범 예방시설물을 설치하고 있으나, 해당 시설물에 대한 설치기준이 없는 실정이다. 이렇듯 중앙분리대 설치기준의 부재로 인해 중앙선침범사고 발생과 이에 따르는 경제적인 교통사고 비용손실, 그리고 중앙분리대의 과다설치로 인한 국가 재원의 낭비는 간과할 수 없는 문제점을 내포하고 있다. 이러한 점에 착안하여 기존에 지방부 2차로 도로의 직선부에 대한 중앙선침범사고 예측모델이 개발되었고 본 연구에서는 그 연장선상에서 지방부 2차로 도로의 곡선부에 대한 중앙선침범사고 예측모델에 대한 중앙선침범사고 예측모델의 개발을 통해 중앙선침범사고에 대한 사회적 비용을 산정하고, 현재 설치하여 운영중인 중앙선침범 예방시설물의 설치비용간의 비용-편익분석을 통해 얻어진 기준으로 중앙선침범 예방시설물 설치의 가부에 대한 보다 현실적이고 비용-효율적인 중앙선침범 예방시설물 설치기준을 제시함으로써 교통사고 비용손실을 최소화하고, 중앙분리대의 효율적 설치방안의 도입을 통한 경제적 이익창출을 도모하고자 한다.