• Membrane and Water Treatment
• /
• v.4 no.1
• /
• pp.11-25
• /
• 2013

Emulsion liquid membrane (ELM) process suffers from emulsion instability problem. So far, emulsion produced by mechanical methods such as stirrer and homogenizer has big size and high emulsion breakage. This paper discussed the application of emulsion produced by sonicator to extract cadmium in a batch ELM system. The emulsions consist of N,N-Dioctyl-1-octanamine (trioctylamine/TOA), nitrogen trihydride (ammonia/NH4OH), sorbitan monooleate (Span 80), and kerosene as carrier, stripping solution, emulsifying agent, and organic diluent, respectively. Effects of comprehensive parameters on extraction efficiency of Cd(II) such as emulsification time, extraction time, stirring speed, surfactant concentration, initial feed phase concentration, carrier concentration, volume ratio of the emulsion to feed phase, and pH of initial feed phase were evaluated. The results showed that extraction efficiencies of Cd(II) greater than 98% could be obtained under the following conditions: 15 minutes of emulsification time, 4 wt.% of Span 80 concentration, 4 wt.% of TOA concentration, 15 minutes of extraction time, 250 rpm of stirring speed, 100 ppm of initial feed concentration, volume ratio of emulsion to feed phase of 1:5, and initial feed pH of 1.53.

• Journal of the Korean Society for Heat Treatment
• /
• v.7 no.3
• /
• pp.206-218
• /
• 1994

In 50%$NH_3+Air+N_2$ atmospheres, the effect of air additions on the growth characteristics of the compound layer during oxynitriding at $570^{\circ}C$ for 2hr in carbon and alloy steels has been investigated. The ammount of apparent residual ammonia during oxynitriding has shown to be increased with air additions(9~36 Vol. %) and X-ray diffraction analysis of case oxynitreded has shown that the compound layer consist of ${\varepsilon}-Fe_{2-3}$(N, C) phase and ${\gamma}^{\prime}-Fe_4$(N,C) phase. In the case of carbon steels, the thickness of oxide layer, compound layer and porous layer and the amount of ${\varepsilon}-Fe_{2-3}$(N,C) phase in the compound layer were increased with additions of air in 50%$NH_3+N_2$ atmospheres. At the same gas composition, the thickenss of oxide layer, compound layer and porous layer in alloy steels showed slightly thin layer thickness compared to those of carbon steels and the ${\gamma}^{\prime}-Fe_4$(N,C) phase in the compound layer of alloy steels was found barely. Therefore, the most obvious effect of air addition in the gas nitriding atmosphere has been found to in crease further kinetics of nitriding reaction.

• Proceedings of the KIEE Conference
• /
• 1997.07c
• /
• pp.825-828
• /
• 1997

The ferroresonance characteristics in 3 phase transformer is analysed in this paper using EMTP simulations under the consideration of lateral length of the primary cable. The ferroresonant overvoltage or undervoltage may occur in cable-fed 3 phase transformer when single phase switching is made in relatively remote point from the transformer, and this phenomena is closely related to the lateral length of the cable. This paper shows the voltage characteristics concerned with the transformer ferroresonance and the proper lateral length of the cable for reducing the voltage in 3 phase installation, through some case studies.

• Journal of the Korean Society for Heat Treatment
• /
• v.24 no.3
• /
• pp.133-139
• /
• 2011

This study has been investigated for tensile properties with lead-free brass containing 1 wt.% of Bi. And also characteristic of corrosion resistance was analyzed by polarization test. An increase of tempering temperature was found to tend to decrease tensile strength, and percentage of elongation was shown to be the lowest value at $300^{\circ}C$. On the other hand, the elongation was increased with an increase of tempering temperature after $300^{\circ}C$. The change of mechanical properties was closely related with the content and shape of acicular Witmanst$\ddot{a}$tten ${\alpha}$ formed at the interface of ${\beta}$ phase as well as in ${\beta}$ phase. Tensile strength had a tendency to be decreased with an increase of test temperature. The elongation was shown to be the lowest value at around $300^{\circ}C$, while it began to increase as test temperature rose after $300^{\circ}C$. It might be speculated that the reason that elongation was decreased was found to form bismuth film at the interface of ${\alpha}/{\beta}$ phase leading to be easily brittle when loaded by tensile stress. The lead-free brass containing 1 wt.% of Bi had similar characteristic of corrosion resistance with a free-cutting brass with 3.4 wt. % of Pb in spite of higher fraction of ${\beta}$ phase.

• Journal of Magnetics
• /
• v.5 no.3
• /
• pp.73-75
• /
• 2000

Undoped and Cr-doped samples of electrooptic material KTiOPO$_4$ were studied by $^{31}$P nuclear magnetic resonance (NMR). Spin-lattice relaxation time ($T_1$) measurements manifested phase transition behaviors that are attributed to changes in the dominant charge carriers in different temperature ranges.

• Journal of computational fluids engineering
• /
• v.20 no.3
• /
• pp.1-7
• /
• 2015

When the steam is used as working fluid in fluid machinery, different from other gases as air, phase transition (steam condensation) can occur and it affects not only the flow fields, but also machine performance & efficiency. Therefore, considering phase transition phenomena in CFD calculation is required to achieve accurate prediction of steam flow and non-equilibrium wet-steam model is needed to simulate realistic steam condensing flow. In this research, non-equilibrium wet-steam model is implemented on in-house code(T-Flow), the flow fields including phase transition phenomena in convergent-divergent nozzle are studied and compared to results of advance researches.

• Journal of Environmental Health Sciences
• /
• v.28 no.5
• /
• pp.28-34
• /
• 2002

Antigenicity of Rhodotrula rubra isolated from pulmonary tissue of pulmonary tuberculosis patients was studied by means of agglutination reaction with R. rubra whole cell antiserum. And the serological reactivity of crude polyfac charide from R. frubra, Candida albicans, Candida tropicalis, Candida, glabrata, and Saccharomyces cerevisiae ATCC 26603 with antiserum to R. rubra whole cell was studied by means of immunodiffusion test. R. rubra showed stationary phase after 48h when it was cultured in GYEP broth. While agglutinogen titer was 1:64 at lag phase, agglutinogen titer was 1 :256 after 20h. After growth of R. rubra on different 11 media, nutritional environment showed similar agglu-tination reartivity. The agglutinogen titer of C. albicans, C. tropicalis, C. giabrata, which were isolated from patient's expectoration, to R. rubra antiserum by means of agglutination reaction were 1:16, respectively. But, Sacch. cervisiae ATCC26603 was negative. Those results were lower than that of R. rubra agglutinogen titer 1:256. As a result of immu-nodiffusion test with crude polysaccharide extracted from cell wall of R. rubra, C. albicans, C. tropicalis, C. glabrata, Sacch. cervisiae ATCC26603, precipitin line was found only with R. rubra, of which antibody titer was 8.

• Proceedings of the KIEE Conference
• /
• 2004.05b
• /
• pp.132-135
• /
• 2004

In generally, compared with VHF band, electromagnetic waves of UHF band have a low influence for external noise. We can detect the real abnormality with several pC in GIS using UHF method. Recently, it has applied to use the external UHF sensor attached on spacer to GIS of existing substation. In this paper, we firstly described the technique of the partial discharge measurement using frequency analysis and phase analysis in UHF band. Secondly, we presented the results of sensitivity, the relationship of dBm-pC and diagnosis of the reason of PD source by phase analysis. And then, we report the diagnosis result of partial discharge on 800kV GIS in domestic substation. rge diagnosis of GIS.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2004.11a
• /
• pp.289-292
• /
• 2004

반도체 소자의 파괴 원인으로는 주로 열, 전압, 전류, 진동 및 압력 등이 있다. 이 중에서 전압과 열을 스트레스 인자로 적용하여 가속열화 시험을 진행하였다. 전압 및 열에 의한 소자의 열화정도를 파악하기 위해 현재 상용화되어 있는 Phase Control Thyristor 중 $V_{DRM}\;=\;1500V,\;V_{BRM}\;=\;1500V, \;T_{HS}\;=\;-40{\sim}125^{\circ}C$ 정도의 사양을 가지는 소자를 사용하였다. 열화에 의한 여러 가지 변동특성 중에서 소자의 순방향 및 역방향 항복특성의 변화와 누설전류의 변화에 대해 실험을 통해 알아보았다.

• Korean Journal of Microbiology
• /
• v.37 no.3
• /
• pp.228-233
• /
• 2001

The acid tolerance response (ATR) of log-phase Salmouella enterica seroyar Typhimurium is induced by acid adaptation below pH4.5 and will protect cells against more severe acid. Two distinctive ATR systems in thisorganism are a log-phase and stationary-phase ATR in which acid adaptations trigger the synthesis of acid shockproteins (ASPs). We found that log-phase ATR system was strongly affected by environmental factor, low tem-perature, $25^{\circ}C$. Exposure to low temperature and mild acid has been shown to increase acid survival dra-matically, and this survival rate was showed higher than $37^{\circ}C$. Especially unadapted cells at $25^{\circ}C$ presented tenthousand folds survival increasing when compared with cells at $37^{\circ}C$. The degree of acid tolerance of rpoSwhich is blown to be required for acid tolerance more increase than $37^{\circ}C$. Even though AIR pattern of rpoSbetween unadapted and adapted was showed similar at pH 3.1, rpoS-dependent ATR system also has beendetected in low temperature because rpoSAp prevents sustained acid survival at $25^{\circ}C$. Therefore the resultssuggest low temperature ATR system requires rpoS-dependent and -independent both. To investigate the basisfor low temperature related ATR system, gene that was participated for low temperature acid tolerance (lat) wasscreened in virulent S. enterica serovar Typhimurium UKl Using the technique of P22- MudJ (Km, lacZ)-directed lacZ operon fusion, LF452 latA‥‥MudJ was isolated. The latA‥‥MudJ of S. enterica Typhimurium pre-vented low temperature acid tolerance response. Therefore latA is considered one of the important genes for acidadaptation.