• Journal of Electrical Engineering and Technology
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• 제10권4호
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• pp.1786-1795
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• 2015

It is common practice to identify the insulation faults of GIS through monitor the contents of SF₆ decomposed components. Partial discharges (PD) could lead to the decomposition of SF₆ dielectric, so new reactions usually occur in the mixture of the newly decomposed components including traces of H₂O and O₂. The new reactions also cause the decomposed components to differ due to the different amounts of H₂O and O₂ even under the same strength of PD. Thus, the accuracy of assessing the insulation faults is definitely influenced when using the concentration and corresponding change of decomposed components. In the present research, a needle-plate electrode was employed to simulate the PD event of a metal protrusion insulation fault for two main characteristic components SO₂F₂ and SOF₂, and to carry out influence analysis of trace H₂O and O₂ on the characteristic components. The research shows that trace H₂O has the capability of catching an F atom, which inhibits low-sulfide SF_x from recombining into high-sulfide SF₆. Thus, the amount of SOF₂ strongly correlates to the amount of trace H₂O, whereas the amount of SO₂F₂ is weakly related to trace H₂O. Furthermore, the dilution effect of trace O₂ on SOF₂ obviously exceeds that of SO₂F₂.

• 한국산학기술학회논문지
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• 제6권2호
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• pp.144-148
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• 2005

앞선 논문에서 ${K_2}O$-CaO-${P_2}{O_5}$유리의 용출 특성을 이용한 유리질 비료로서의 가능성을 보고한바 있으며, 본 연구에서는 ${K_2}O$-CaO-${P_2}{O_5}$ 조성에 식물의 성장에 필요한 미량원소인 B, Mg, Zn, Fe, Cu, Co, Mo을 첨가한 유리를 제조하였으며, 제조된 유리의 용출 특성을 pH와 ICP분석을 통하여 관찰하였다 미량원소가 첨가된 유리의 경우 첨가전의 pH값의 변화와 차이가 없었으며, 모유리의 안정화에 영향을 미치지 못함을 알 수 있었다. 첨가된 미량원소의 용출량은 모유리조성과 첨가된 함량에 비례하였으며, 이러한 원소들의 용출속도는 모유리 조성에 의하여 결정되었다.

• 약학회지
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• 제17권1호
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• pp.41-43
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• 1973

Trace-amounts of Diptered and DDVP in fishes could be separated and identified by thin layer chromatography and gas chromatography with DEGS-H$_{3}$PO$_{4}$ column.

• 한국환경과학회:학술대회논문집
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• 한국환경과학회 2003년도 International Symposium on Clean Environment
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• pp.65-68
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• 2003

A quantitative study of the amount of air transported between the boundary layer and the free atmosphere is important for understanding air quality and upper tropospheric ozone, which is a greenhouse gas. Frontal systems are known to be an effective mechanism for the vertical transport of pollutants. Numerical experiments have been performed with a simple two-dimensional front model to simulate vertical transport of trace gases within developing cold fronts. Three different trace gases experiments have been done numerically according to the different initial fields of trace gases such as aerosol, ozone and $H_2O_2$. Trace gas field tilts to the east while the front tilts to the west. Aerosol simulation shows that pollutants can be transported out of the boundary to altitudes of about 10 km. The stratospheric ozone is brought downwards in a tropopause fold behind of the frontal surface. The meridional gradient in trace gas ($H_2O_2$) can cause a complicate structure in the trace field by the meridional advection.

• 한국대기환경학회지
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• 제13권5호
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• pp.371-381
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• 1997

Precipitation sampls were collected in Chonju-city during October 1994 to September 1995 and were analysed for major ions (N $a^{+}$, $K^{+}$, $Ca^{2+}$, $Mg^{2+}$, C $l^{[-10]}$ , NO/$_3$, S $O_4$$^{2-}$) and trace metals (Al, Cd, Ni, Pb, Sr, Zn) in addition to pH, in order to understand the chemical characteristics of acid rain and to estimate the origin of the determined ions. Most rain showed a neutral or alkaline character, and only 35% had a pH lower than 5.6. S $O_4$$^{2-}$ and N $O_3$$^{[-10]}$ are identified as the primary contributors to precipitation acidity in this region. Neutralization of precipitation acidity occurs as a result of the dissolution of alkaline compounds containing $Ca^{2+}$, $Mg^{2+}$ and $K^{+}$. S $O_4$$^{2-}$ and N $O_3$$^{[-10]}$ precipitation concentrations exhibit a seasonal pattern in which higher concentrations are observed during spring months and lower concentrations during summer months. However, the seasonal behavior of $H^{+}$ concentrations differs from this pattern, in that the highest concentrations occur during autumn months, owing to the different influence of neutralization processes. In all rain, S $O_4$$^{2-}$ concentration exceeded NO/$_3$$^{[-10]}$ concentration. The contribution of maritime sources to the total S $O_4$$^{2-}$ concentration was very low or negligible. For rain strongly affacted by yellow sand, $Ca^{2+}$, $Mg^{2+}$ and $K^{+}$ ions show a sharp increase in concentration, reflecting the increased amount of dust and soil suspended in atmosphere. At the same time, S $O_4$$^{2-}$ and N $O_3$$^{[-10]}$ concentrations are at their highest levels while $H^{+}$ values are not comparably elevated, presumably beacause much of the acidity has been neutralized by alkaline substances. The seasonal variance of trace metal concentrations in rainwater is similar to that of major cations. The annual wet flux of acidic pollutants and trace metals wat calculated to be as follows: N $O_3$$^{[-10]}$ ; 2.32 g/$m^2$, S $O_4$$^{2-}$, 5.34 g/$m^2$, Al; 6.30 mg/$m^2$, Cd; 0.62 mg/$m^2$, Ni; 4.08 mg/$m^2$, Pb: 9.76 mg/$m^2$, Sr; 5.94 mg/$m^2$, Zn; 111 mg/$m^2$./$m^2$.

• 한국대기환경학회지
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• 제16권1호
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• pp.61-68
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• 2000

Gas-phase hydrogen peroxide(H2O2) concentrations were measured to investigate it's distribution in the ambient air in downtown Seoul(Kwanghwamum and Mullae-dong). These measurements were made during four season, from April 30, 1998 to January 29, 1999, using Cold Trap and HPLC. Measurements were also made of other photochemical oxidants and trace gases(O3, NO2, CO and SO2) and meteorological parameters(relative humidity, temperature, solar radiation and wind speed). The mean of all observations was 0.10 ppbv and the range measured was below the level of detection(>0.01 ppbv) to 0.47ppbv. The higher seasonal mean concentrations showed during the summer(0.21 ppbv) and concentrations of H2O2 showed a diurnal variation with maximum concentrations in the afternoon(12:30∼14:00). The results from the corrrelation analysis showed that the concentration of gaseous H2O2 is strongly dependent on the other air pollutants(NO2, CO and O3) and meteorological parameters(relative humidity, temperature and solar radiation.)

• Bulletin of the Korean Chemical Society
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• 제29권10호
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• pp.1932-1936
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• 2008

A new analytical method using 1-(2-pyridylazo)-2-naphthol modified $SiO_2$ nanoparticles as solid-phase extractant has been developed for the preconcentration of trace amounts of mercury(II) in different water samples. Conditions of the analysis such as preconcentration time, effect of pH, sample volumes, shaking time, elution conditions and effects of interfering ions for the recovery of analyte were investigated. The adsorption capacity of nanometer $SiO_2$-PAN was found to be 260 ${\mu}molg^{-1}$ at optimum pH and the detection limit (3$\sigma$) was 0.48 ${\mu}gL^{-1}$. The extractant showed rapid kinetic sorption. The adsorption equilibrium of mercury(II) on nanometer $SiO_2$-PAN was achieved just in 5 mins. Adsorbed mercury(II) was easily eluted with 5 mL of 6 M hydrochloric acid. The maximum preconcentration factor was 50. The method was applied for the determination of trace amounts of mercury(II) in various water samples and industrial effluents.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2004년도 추계학술대회
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• pp.96-98
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• 2004

At the previous papers, we showed that K2O-CaO-P2O5 glasses had a solubility in air so that they could be used for glass fertilizer. In this work, we fabricated the Eco-glass fertilizer containing trace elements such as B, Mg, Zn, Fe, Cu, Co, and Mo by a melt-quenching process and the dissolution properties of these glasses were investigated with pH meter and ICP analyzer. In case of the glasses containing the trace elements, effect of trace elements on the dissolutions is not obvious and ignorant the stability of mother glass. Also, the dissolution amounts of each trace elements depend on the mother glass composition and the quantity of each trace element, and mother glasses determined the dissolving velocity of chemical elements.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.333-333
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• 2011

We studied the H/D exchange kinetics of pure and acid dopped water-ice film by using the techniques of reactive ions scattering (RIS) and low energy sputtering (LES) with low kinetic energy cesium ion beam (<35 eV). From RIS, neutral water isotopomers were detected in the form of cesium-molecule ion clusters, $CsX^+$ (X= $H_2O$, HDO, $D_2O$). Ionic species, like $H_3O^+$, $DH_2O^+$, $D_2HO^+$, $D_3O^+$, adsorbed on the surface were ejected via LES process. Those techniques allowed us to trace the isotopomeric populations of water-ice film. To show the catalytic effect of excess proton in the H/D exchange reaction, our study was conducted with two types of water-ice films. In film 1, about 0.5 BL of $H_2O$ was adsorbed on HCl (0.1 ML) dopped $D_2O$ (8 BL) film. In film 2, similar amount of $H_2O$ used in film 1 was adsorbed on pure $D_2O$ film. Kinetic data were obtained from each film type for 90-110 K (film 1) and 110-130 K (film 2) and fitted with numerically integrated lines. Through the Arrhenius plot of kinetic coefficient deduced from fitting of the H/D exchange reaction, the activation energy of film 1 and 2 were estimated to be $10{\pm}3kJmol^{-1}$ and $17{\pm}4kJmol^{-1}$. This activation barrier difference could be understood from detailed pictures of H/D exchange. In film 2, both the formation of ion pair, $H_3O^+$ and OH. and proton transfer were needed for the H/D exchange. However, in film 1, only proton transfer was necessary but ion pair formation was not, so this might reduce the activation energy.

• 한국세라믹학회지
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• 제31권10호
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• pp.1147-1158
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• 1994

From Zr(O-nC3H7)4-H2O-C2H5OH-HNO3 starting solutions, MgO-doped stabilized zirconia fibers with varying content of MgO (10~18 mol%) from different MgO sources were fabricated by sol-gel method. The MgO sources used are magnesium nitrate hexahydrate, magnesium acetate tetrahydrate, and magnesium ethylate. The phase transformation studies of a drawn MgO-ZrO2 fiber were carried out using X-ray diffraction, IR spectroscopy, and Raman spectroscopy. The microstructure, tensile strength, and microporosity of fibers were investigated using SEM, tensile strength test, and microporosimeter. Although various MgO sources such as magnesium nitrate, acetate, and ethylate were used, the crystallization behavior of MgO-ZrO2 fibers at different temperatures could be summarized as follows: CubiclongrightarrowMetastable TetragonallongrightarrowMonocliniclongrightarrowCoexistence of Monoclinic and CubiclongrightarrowCubic(trace of monoclinic). At 150$0^{\circ}C$, the phase transformation of MgO-ZrO2 fibers shows the following change depending on the amount of MgO[Mg(NO3)2.6H2O]: At 10 mol%, both monoclinic and cubic phase coexist, at 12 mol%, monoclinic phase decreases rapidly, and then at 14 mol%, only cubic phase remains. When the MgO-ZrO2 fibers containing 12 mol% magnesium nitrate were heated at 80$0^{\circ}C$ for 1hr, average tensile strength of fibers is 4.0 GPa at diameters of 20 to 30 ${\mu}{\textrm}{m}$. As the heat-treatment temperatures increase to 100$0^{\circ}C$ for 1 hr, tensile strength of MgO-ZrO2 fibers decreases rapidly to 0.7 GPa.