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박영훈,박평주 대한금속재료학회(대한금속학회) 1978 대한금속·재료학회지 Vol.17 No.4
황산철 용액으로부터 Jarosite로서 鐵을 침전시키는데 영향을 미치는 측정가능한 因子中(Seeding 量, 알카리量, 산도, 온도)에 관해 실험을 하였다. 이 中에서 小量의 Seeding에 의해서 초기반응속도를 증가시킬 수 있었으며 산도조절이 탈철에 가장 큰 영향을 미치는데 반응액을 中和하여 가장 最適 酸度(PH 1.5정도)로 調節하면서 沈澱시키므로 속도식에는 이 酸度의 영향이 나타나지 않았다. 小量의 Seed를 첨가하여 Jarosite로서 침전시킬 때 脫鐵反應의 速度論的 實驗式은 다음과 같이 표현할 수 있다. 1/[Fe]²-1/[Fe]²_0=2Kt 沈澱反應에 對한 實驗式으로부터 活性化 energy는 18Kcal/mole이었다. This study was concentrated on the experimentally measurable factors which affect the iron precipitation as Jarosite from ferric sulfate solutions. Of seeding quantity, alkali ions, the pH value and temperature, the seeding addition increased the initial rate of iron precipitation and the pH was found to have the greatest effect on the precipitation reaction. To expedite the precipitation of iron as Jarosite during the reaction, the constant pH value of 1.5 was the most preferable. The experimental rate expression for the iron precipitation as Jarosite was as follows: 1/[Fe]²-1/[Fe]²_0=2Kt The activation energy for the reaction was found to be 18Kcal/mole.
한정환,박평주 대한금속재료학회(대한금속학회) 1983 대한금속·재료학회지 Vol.21 No.8
A study on the decomposition of zinc cobaltate was made to improve the extraction of cobalt from the cobalt cake (Cobalty-Nitroso-β-Naphthol) which is produced as by-products at the hydrometallurgical process of zinc. It has been reported that zinc cobaltate was formed during the roasting process of the cobalt cake. Zinc cobaltate was prepared from the nitrate mixtures by drying them at 200℃ for 9 hrs and heating them at 400℃ for 4 hrs. The final product was ZnCo₂O_(3.962). It was observed that zinc cobaltate was decomposed into ZnO and Co₃O₄in the temperature range of 450-810℃ and Co₃O₄was again decomposed into CoO in the temperature range of 820-890℃, thus gave final products of ZnO and CoO over 920℃. Leachability of cobalt from the decomposed products over 920℃ has been determined in various concentrations of sulfuric acid. It was observed that 97.6% leachability of cobalt in 5N-H₂SO₄was obtained. The reaction order and apparent activation energy of the decomposition of zinc cobaltate was respectively 0.7 and 63.6 ㎉.
Lee, Sang H.,Lee, Seonki,Lee, Kibaek,Nahm, Chang H.,Kwon, Hyeokpil,Oh, Hyun-Suk,Won, Young-June,Choo, Kwang-Ho,Lee, Chung-Hak,Park, Pyung-Kyu American Chemical Society 2016 Environmental science & technology Vol.50 No.16
<P>Recently, membrane bioreactors (MBRs) with quorum quenching (QQ) bacteria entrapping beads have been reported as a new paradigm in biofouling control because, unlike conventional post-biofilm control methods, bacterial QQ can inhibit biofilm formation through its combined effects of physical scouring of the membrane and inhibition of quorum sensing (QS). In this study, using a special reporter strain (Escherichia coli JB525), the interaction between QS signal molecules and quorum quenching bacteria entrapping beads (QQ-beads) was elucidated through visualization of the QS signal molecules within a QQ-bead using a fluorescence microscope. As a result, under the conditions considered in this study, the surface area of QQ-media was likely to be a dominant parameter in enhancing QQ activity over total mass of entrapped QQ bacteria because QQ bacteria located near the core of a QQ-bead were unable to display their QQ activities. On the basis of this information, a more efficient QQ-medium, a QQ hollow cylinder (QQ-HC), was designed and prepared. In batch experiments, QQ-HCs showed greater QQ activity than QQ:beads as a result of their higher surface area and enhanced physical washing effect because of their larger impact area against the membrane surface. Furthermore, it was shown that such advantages of QQ-HCs resulted in more effective mitigation of membrane fouling than from QQ-beads in lab-scale continuous MBRs.</P>
Effect of Bubbling on the Primary Silicon in Hypereutectic Al-Si Alloy
Choi, Jung Pyung,Lee, Sang J.,Yoon, Eui Pak,Yoon, W.Y.,Kim, M.H.,Kim, K.H. Trans Tech Publications, Ltd. 2004 Materials science forum Vol.449 No.-
<P>This paper investigates the effect of bubble on the primary Si size in Al-18wt.%Si alloy. The primary Si size observed was varied with bubble size and bubbling time in bubble process. The effect of the holding temperature of the melt in bubbling process was also investigated. In water model, as the injecting bubble size decreases, the residual bubble size in the water decreases and the residual bubble conservation time in the water increases. Also in the experiment of Al melt, the primary Si size decreases, as the injecting bubble size decreases and as the bubble processing time increases. Pore was observed at the center of primary Si. This pore was observed at many Si phases. So, this experiment suggests that the bubble can be used as nucleation sites of primary Si.</P>
Pyung Hun Chang,Kyungbin Park,Sang Hoon Kang,Krebs, H. I.,Hogan, N. IEEE 2013 IEEE/ASME transactions on mechatronics Vol.18 No.2
<P>Inspired by previous research on the promising internal model-based impedance control (IMBIC) scheme, it was implemented and experiments were undertaken to determine the stochastic estimation of human arm impedance. A 2-DOF selective compliant assembly robot arm (SCARA) robot with significant nonlinear frictions was used in the experiments in order to test the accuracy and reliability of the estimation under nonlinear frictions, with the IMBIC and with a proportional derivative (PD) control, respectively. After the stochastic estimation method with the SCARA robot and the IMBIC was validated using a spring array, the method was applied to the estimation of human arm impedance. The experimental results demonstrated that the stochastic estimation using the IMBIC yields accurate and reliable estimations even under substantial frictions: the multiple coherence functions exceeded 0.95 throughout the frequency range investigated and the estimated magnitudes and phases matched well with a second-order best-fit model. Furthermore, the best-fit model demonstrated reasonable agreement with the results of previous research. The stochastic estimation using the IMBIC has also demonstrated effectiveness in the estimation of human arm impedance using conventional robots.</P>
Effect of SKL2001 on the neuronal survival mechanism in Parkinson’s disease
Pyung jun Choi,Sangtaek Oh,Hyunjeong Liew,S. Oh,H. Liew 대한독성 유전단백체 학회 2017 Molecular & cellular toxicology Vol.13 No.2
The Wnt/β-catenin pathway affects the differentiation of various cell types including mesenchymal stem cells. Previously, we evaluated SKL2001 as a novel agonist of the Wnt/β-catenin pathway. SKL2001 upregulated β-catenin-responsive transcription by increasing the intracellular β-catenin protein level and inhibiting the phosphorylation of β-catenin. Furthermore, SKL2001 disrupted Axin/β-catenin interaction and induced an increase in survivin, an inhibitor of apoptosis. We investigated the effect of SKL2001 on a Parkinson’s disease cell model consisting of SHSY5Y cells induced by 6-hydroxydopamine. Consequently, we discovered that SKL2001 is effective in promoting neuronal survival and functional recovery by activation of the Wnt/β-catenin signaling pathway
Bae, Jin H.,Park, Beom Gi,Jung, Eunok,Lee, Pyung-Gang,Kim, Byung-Gee Springer-Verlag 2014 Applied microbiology and biotechnology Vol.98 No.21
<P>A major problem of long-chain fatty acid (LCFA) hydroxylation using Escherichia coli is that FadD (long-chain fatty acyl-CoA synthetase), which is necessary for exogenous LCFA transport, also initiates cellular consumption of LCFA. In this study, an effective method to prevent the cellular consumption of LCFA without impairing its transport is proposed. The main idea is that a heterologous enzyme which consumes LCFA can replace FadD in LCFA transport. For the model heterologous enzyme, CYP153A from Marinobacter aquaeolei, which converts palmitic acid into ω-hydroxy palmitic acid, was expressed in E. coli. When fadD was deleted from an E. coli strain, CYP153A indeed maintained the ability to transport LCFA. A disadvantage of fadD deletion mutant is the fact that FadD deficiency downregulates the transcription of fadL (outer membrane LCFA transporter) via FadR (fatty acid metabolism regulator protein), was solved by fadL overexpression from a plasmid. In addition, the overexpression of fadL was able to offset catabolite repression on fadL, allowing glucose to be used as the primary carbon source. In conclusion, the strain with fadD deletion and fadL overexpression showed 5.5-fold increase in productivity compared to the wild-type strain, converting 2.6 g/L (10.0 mM) of palmitic acid into 2.4 g/L (8.8 mM) of ω-hydroxy palmitic acid in a shake flask. This simple genetic manipulation can be applied to any LCFA hydroxylation using E. coli.</P>