• 한국표면공학회지
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• 제36권5호
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• pp.364-372
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• 2003

In continuous galvanizing process, dissolution of iron into molten zinc results in a fairly great amount of dross. In order to decrease dross, the amount of dissolved iron of strip in molten zinc was investigated in the range of 0∼0.22%Al content, 440∼$470^{\circ}C$ strip temperature and 3∼60 sec dipping time. Uniform Fe-Al-Zn inhibition layer was formed in the coating layer/strip interface not only in the grain boundary but also in the grain of substrate with the increase of Al content in the zinc pot, while the amount of iron dissolution was decreased. Inhibition layer was unstable as the dipping time and strip temperature increased and the amount of iron dissolution increased.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 1999년도 춘계학술발표회 초록집
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• pp.97-97
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• 1999

Dross formation in the zinc bath is inevitable under any condition as long as coating process on steel strip continues. Thus, bath aluminum and temperature are precisely managed to suppress the increase of dross. Also, excessive dross for normal coating process is generally eliminated physically by bubbling and skimming. Total amount of dross in the bath can be sometimes high enough to cause coating defect. On the other hand, local concentration of dross can make coating defect even with satisfactory level of total amount of dross. Reduction of dross in the bath was attempted by using ceramic foam filter made of mainly alumina. Dross in molten zinc was almost reduced to the levels of solubility of iron and aluminum in molten zinc at $450~460^{\circ}C$. Their solubility levels were confirmed by thermodynamic calculations or DEAL program. Two kinds of filters were tested for dross reduction. One was #20 ppi, porous per inch, and the other #30 ppi filter. Both were effective in reducing the bath dross to the solubility levels at the static state. Bath iron was reduced by 24 wt% and 19 wt% with #20 filter, and by 35 wt% and 29 wt% with #30 filter for GI and GA pot, respectively. Also, ceramic foam filter did not make any harm to the zinc bath composition after filtering test.

• 대한기계학회논문집B
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• 제25권10호
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• pp.1392-1399
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• 2001

The flow fields inside a molten Zn pot of continuous hot-chip galvanizing process were investigated experimentally. With varying several parameters including the strip speed Vs, flow rate Q of induction heater. scrapper location and baffle configuration, instantaneous velocity fields were measured using a PIV velocity field measurement technique. Inside the strip region, counter-clockwise rotating flow is dominant. The general flow pattern inside the strip region is nearly not influenced by the strip speed Vs, flow rate Q and the scrapper location. In the exit region, the flow separated from the moving strip due to the existence of a stabilizing roll ascends to the free surface, for the cases of no scrapper and scrapper detached form the roll. On the other hand, the ascending flow to the free surface is decreased, as the flow rate Q of induction heater increases. By installing a baffle around the uprising strip, the flow moving up to the stabilizing roll decreases. In addition, B-type baffle is better than A-type baffle in reducing speed of flow around the stabilizing rolls. However, the flow ascended to the free surface is largely influenced by changing the flow rate Q, and the scrapper location, irrespective of the baffle type.

• Bulletin of the Korean Chemical Society
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• 제32권7호
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• pp.2316-2318
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• 2011

A novel technology has been developed for the synthesis of thioglycolic acid (TGA)-capped CdSe quantum dots (QDs) in aqueous medium. The reaction was carried out in air atmosphere with one-pot by using $SeO_2$ to replace Se or $Na_2Se$. The technological parameters including refluxing time, pH values and molar ratios of selenium to cadmium had significant influence on the luminescence properties of CdSe QDs. Furthermore, the obtained QDs were characterized by fluorescent spectroscopy, X-ray powder diffraction (XRD) and transmission electron microscopy (TEM), respectively. The results demonstrated that the CdSe QDs were of zinc-blended crystal structure in a sphere-like shape.

• 대한기계학회논문집B
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• 제23권10호
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• pp.1265-1273
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• 1999

PIV(Particle Image Velocimetry) velocity field measurements inside the snout of a1/10 scale model of the Zn plating process were carried out at the strip speed $V_s=1.5m/s$. Aluminum powder particles ($1{\mu}m$) and atomized olive oil ($3{\mu}m$) were used as seeding particles to simulate the molten Zinc flow and deoxidization gas flow, respectively. A pulsed Nd:Yag laser and a $2K{\times}2K$ high-resolution CCD camera were synchronized for the PIV velocity field measurement. From flow visualization study, it is found that the liquid flow in the Zn pot is dominantly governed by the uprising flow caused by the rotating sink roll, with its effect on the steel strip inside the snout largely diminished by installing of the snout. The deoxidization gas flow in front of the strip inside the snout can be characterized by a large-scale vortex rotating clockwise direction formed by the moving strip. In the rear side of the strip, a counter-clockwise vortex is formed and some of the flow entrained by the moving strip impinges on the free surface of molten zinc. The liquid flow in front of the strip is governed by the flow entering the snout, caused by the spinning sink roll. Just below the free surface a counter-clockwise vortex is formed near the snout wall. The moving strip affects dominantly the flow behind the strip inside the snout, and large amount of the liquid flow follows the moving strip toward the sink roll. The thickness of the flow following the strip is very thin in the front side due to the uprising flow, however thick boundary layer is formed in the rear side of the strip. Its thickness is increased as moving downstream toward the sink roll. Inside the snout, the deoxidization gas flow above the free surface is much faster than the liquid flow in the zinc pot. Due to the larger influx of the flow following the moving strip in the rear side of the strip, higher percentage of imperfection can be anticipated on the rear surface of the strip.

• 한국표면공학회지
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• 제32권1호
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• pp.21-30
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• 1999

Coating adherance behavior of low carbon steels, produced by POSCO, Korea, was studied in order to study the characteristics of hot rolled galvanized iron(HGI) manufactured without pickling line and the development of its process. Galvanizing experiments were carried out in zinc pot with 0.2wt% Al after hot rolled plates with scale were reduced at $550~750^{\circ}C$ in 10~30% hydrogen gas atmosphere during 60~400seconds. The reduced plates and coated products were examined by SST, XRD, SEM and EPMA on their surfaces and cross sections. Coating layer of HGI manufactured with pickling line was composed of retained scale, Fe-Zn-Al compound, Fe-Zn compound ($\delta_1\;and\;\zeta$ Phase) and pure zinc. It was superior to HGI in coating adhesion. It seems to be due to forming of Fe-Zn-Al compound in interface of matrix and retained porous scale.

• Archives of Pharmacal Research
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• 제27권1호
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• pp.19-24
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• 2004

The facile synthesis of a series of 2-(4-hydroxyphenyl)benzofurans (4a-e) is described. The one-pot reaction of 4-substituted phenols with the chloride 1 in the presence of zinc chloride afforded 3-methylthio-2-(4-acetoxyphenyl)benzofurans (2a-e). The compounds 4a-e were obtained from the hydrolysis of 2a-e followed by the desulfurization of the resulting 3-methylthio-2-(4-hydroxyphenyl)benzofurans (3a-e). 5-Methyl-3-p-toluoyl-2 -[4-(3-diethylaminopropoxy)phenyl]benzofuran (7), a $\beta$-amyloid aggregation inhibitor, was synthesized by three steps starting from 4a.

• 한국토양비료학회지
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• 제13권3호
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• pp.85-91
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• 1981

아연비료로서 ZnEDTA와 $ZnSO_4$의 유효도를 평가하기 위해서 수도의 아연흡수 실험을 시도했다. 수도의 아연흡수에 있어서 급원별(給源別) 아연 유효도는 토양에 따라서 차이(差異)가 있었다. pH가 높은 제천(提川) 석회암질(石灰岩質) 토양에서는 ZnEDTA가 $ZnSO_4$보다 수도체아연 농도(濃度)와 아연 흡수량(吸收量)을 증가시키는데 더 유효했다. 그러나 산성(酸性)인 금곡토양의 경우도 ZnEDTA의 유효성이 인정(認定)되지 않았다. ZnEDTA를 처리(處理)한 제천(提川) 석회암질(石灰岩質) 토양에서 생육(生育)한 수도는 $ZnSO_4$ 처리구 수도보다 분얼수와 초장(草丈)이 컸고 건물생산량(建物生産量)도 높았다. 아연급원에 관계없이 아연와 유기물(有機物) 처리구에서 자란 수도의 분얼수, 초장(草丈), 건물생산량(建物生産量)은 모두 다 적었다. 이것은 유기물(有機物)을 첨가(添加)하므로서 시비(施肥) 아연의 고정(固定)이 더 일어나서 수도체의 아연수율이 적기 때문이라고 본다. 아연고정 정도(程度)는 제천(提川) 석회암질(石灰岩質) 토양에서 컸다.

• Corrosion Science and Technology
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• 제9권1호
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• pp.1-7
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• 2010

Cost reduction of products is and will always be a key objective of industrials. However, it is well identified that the wiping process reaches its limits at high line speed in general and especially thin coatings. If wiping models predict that it is possible to reach 32-37 g/$m^2$ of pure Zinc at 180 m/min provided the nozzle to strip distance can be reduced to 6mm, the possibility to reach that process window industrially with sufficient robustness is debated. 3 key problems are reviewed and analyzed: Zinc splashing and liquid drop emissions of various forms, the production of skimming and the noise generated by the nozzles. The available data and models are firstly used to predict phenomena. Secondly, videos and pictures from the lines showing what really happens on the edges especially in case of a strip width change are analyzed. Whereas the predicted level of skimming to remove from the pot is expected very high, it turns out that the target may be very close to the full splashing phenomena and that the most critical industrial situation is related to strip specification changes. It is then expected that the industrial feasibility of the 32-37 g/$m^2$ at 180 m/min will depend strongly on the amount of incoming strip with the same width that can be processed continuously.

• Journal of Microbiology and Biotechnology
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• 제21권6호
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• pp.556-566
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• 2011

A total of 31 Acinetobacter isolates were obtained from the rhizosphere of Pennisetum glaucum and evaluated for their plant-growth-promoting traits. Two isolates, namely Acinetobacter sp. PUCM1007 and A. baumannii PUCM1029, produced indole acetic acid (10-13 ${\mu}g$/ml). A total of 26 and 27 isolates solubilized phosphates and zinc oxide, respectively. Among the mineral-solubilizing strains, A. calcoaceticus PUCM1006 solubilized phosphate most efficiently (84 mg/ml), whereas zinc oxide was solubilized by A. calcoaceticus PUCM1025 at the highest solubilization efficiency of 918%. All the Acinetobacter isolates, except PUCM1010, produced siderophores. The highest siderophore production (85.0 siderophore units) was exhibited by A. calcoaceticus PUCM1016. Strains PUCM1001 and PUCM1019 (both A. calcoaceticus) and PUCM1022 (Acinetobacter sp.) produced both hydroxamate-and catechol-type siderophores, whereas all the other strains only produced catechol-type siderophores. In vitro inhibition of Fusarium oxysporum under iron-limited conditions was demonstrated by the siderophore-producing Acinetobacter strains, where PUCM1018 was the most potent inhibitor of the fungal phytopathogen. Acinetobacter sp. PUCM1022 significantly enhanced the shoot height, root length, and root dry weights of pearl millet seedlings in pot experiments when compared with controls, underscoring the plant-growth-promoting potential of these isolates.