磁鐵鑛 鑛球의 還元特性에 미치는 SiO₂CaO 添加의 影響

김부천,梁勳永,이승원 연세대학교 산업기술연구소 1977 논문집 Vol.7 No.1

Direct reduction of sintered magnetite ore pellets containing 3-6% SiO₂and CaO with the basicity range of 0.5-2.4 has been made in a fixed bed with coke powder in the temperature range of 900-1200℃. Reduction degree of reduced pellets was obtained from the weight loss of the pellets after reduction. Phase change during the reduction was investigated by X-ray diffraction method and microscopic observation. Followings are the results summerized. 1) At 900℃, reduction was only reached to the wustite. Above 900℃, porous metallic iron layers began to appear and the phase of reduction proceeded topochemically towards the inside of the pellet. 2) Lime addition was more effective to the promotion of reducibility at higher temperature. 3) Reduction rate of the pellet containing 3-6% SiO₂followed well the equation, -log (1-R) = Kt, with the exception of the pellet containing higher CaO at the elevated temperature. Activation energy obtained from the above equation was the range of 21.7-25.5㎉/25.5㎉/mole. 4) Due to swelling, at 1100℃, cracking in the reduced pellet was pronounced at the basicity of 1.5, resulting uniform distribution of metallic iron. 5) In order to promote reduction degree as well as not to crack the pellet reduced, long time reduction at lower temperature followed by shorter reduction at higher temperature was recommendable.

다발성 외상환자에서 필수적 단순 방사선검사의 의의

임경수,황성오,임종천,이부수,이강현,이진웅 대한응급의학회 1995 대한응급의학회지 Vol.6 No.2

In the guidelines of Advanced Trauma Life Support(ATLS), essential plane roentgenograms (chest AP vIew, cervical spine lateral view and pelvis AP view) are recommanded when primary survey and resuscitation phase are finished in care of multiple injured patients. A prospective study was carried on 376 multiple trauma patients who admitted to Wonju Christian Hospital from July, 1995 to October. We analyzed clinical significance of essential X-ray in multiple trauma patients, and classified the patients by their status of mentality. The one is alert group when their Glasgow Coma Scale(GCS) is over 13 point, the other is disoriented mentality group when their GCS are below 12 point. The alert group was redivided by presence of clnical symptoms and/or signs, and clinical significances of essential X-ray were analyzed. Among the 376 patients, 330 patients are alert group that their GCS score is over 13 point and 46 patients are disoriented group who's GCS were below 12 point. The detection rate of abnormality in essential X-ray is higher in disoriented group than alert group(cervical-spine lateral view : 13.5% vs 3.0% cheat AP view : 0.4%, pelvis AP view : 0%). This study suggests that their are no needs of taking essential X-ray in patients who is alert in mental state and have no clinical symptoms and/or signs.

Anti-oxidative and Photo-protective Effects of Coumarins Isolated from Fraxinus chinensis

Lee, Bum-Chun,Lee, So-Yong,Lee, Hwa-Jeong,Sim, Gwan-Sub,Kim, Jin-Hui,Kim, Jin-Hwa,Cho, Young-Ho,Lee, Dong-Hwan,Pyo, Hyeong-Bae,Choe, Tae-Boo,Moon, Dong-Cheul,Yun, Yeo-Pyo,Hong, Jin-Tae 대한약학회 2007 Archives of Pharmacal Research Vol.30 No.10

Free radicals and reactive oxygen species (ROS), which are generated by UV irradiation, may cause serious injury to skin cell membranes, DNA and functional proteins. In addition, these agents stimulate the expressions of matrix metalloproteinases (MMPs), which can degrade most components of the extracellular matrix (ECM), including collagen. In order to develop new anti-photoaging agents, five major components from the extract of Fraxinus chinensis extract (FCE) were identified. Two of the major components of FCE were found to be esculin (11.2%) and esculetin (1.9%). FCE ($IC_{50}:\;50.0{\mu}g/mL$ 1, 1-diphenyl-2-picrylhydrazyl (DPPH); $19.8{\mu}g/mL$, superoxide anion radical) and esculetin ($IC_{50}:\;2.1{\mu}g/mL$ DPPH; $0.6{\mu}g/mL$, superoxide anion radical) showed strong antioxidative activities. Of the compounds tested, esculetin showed the strongest scavenging activity against DPPH radicals, followed by superoxide anions from the xanthine/xanthine oxidase system. The intracellular ROS scavenging activity showed that oxidation of 5-(6-)-chloromethyl-2', 7'-dichlorodihydrofluorescein diacetate ($CM-H_2DCFDA$) was effectively inhibited by esculetin, with potent free radical scavenging activity was also shown in UVB-irradiated human dermal fibroblasts (HDFs). Moreover, treatment of UVA-irradiated HDFs with esculetin resulted in dose-dependent decreases in the expression levels of MMP-1 mRNA and protein. From these results, FCE and one of its components, esculetin, were predicted to be potentially useful as ingredients in cosmetics for protecting against photoaging.

Straightforward Synthesis of Metal Nanoparticles and Hierarchical Porous Metals Assisted by Partial Film Boiling Phenomena

Lee, Dong-Wook,Jin, Min-Ho,Lee, Chun-Boo,Lee, Sung-Wook,Park, Jin-Woo,Oh, Duckkyu,Park, Ji Chan,Park, Jong-Soo American Chemical Society 2015 Chemistry of materials Vol.27 No.15

<P>The development of an eco-friendly and economical synthetic pathway of nanomaterials such as metal nanoparticles and nanoporous metals remains a challenging topic in the field of nanomaterials. Here we report a novel and eco-friendly series of synthetic methods from the preparation of metal nanoparticles to the fabrication of hierarchical porous metals by using partial film boiling phenomena established by a reactor with the inverse configuration of conventional Leidenfrost drop reactors, which is much more favorable to large-scale production than conventional Leidenfrost drop reactors. As a result, we have revealed two important facts, which can offer fresh vision to the field of metal nanoparticle and nanoporous metal synthesis. The first one is that Pd and Pt precursor can be reduced to neutral Pd and Pt nanoparticles under basic condition established by partial film boiling phenomena without reducing agents such as ethanol and citric acid. The second one is that when citric acid and ethanol as a mild reducing agent were added into the precursor aqueous solution, citric acid also plays an important role as a pore-forming agent, and ethanol facilitates the aggregation of as-prepared metal nanoparticles, resulting in the formation of nanoporous Pd and Pt. Our work is believed to suggest more eco-friendly and straightforward approaches for fabrication of metal nanoparticles and nanoporous metals. However, further research is required to explore whether our novel synthetic pathway is available to other metal systems.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/cmatex/2015/cmatex.2015.27.issue-15/acs.chemmater.5b00143/production/images/medium/cm-2015-00143w_0013.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/cm5b00143'>ACS Electronic Supporting Info</A></P>

Effects of ginsenosides and their metabolites on voltage-dependent Ca(2+) channel subtypes.

Lee, Jun-Ho,Jeong, Sang Min,Kim, Jong-Hoon,Lee, Byung-Hwan,Yoon, In-Soo,Lee, Joon-Hee,Choi, Sun-Hye,Lee, Sang-Mok,Park, Yong-Sun,Lee, Jung-Ha,Kim, Sung Soo,Kim, Hyoung-Chun,Lee, Boo-Yong,Nah, Seung-Ye Korean Society for Molecular Biology 2006 Molecules and cells Vol.21 No.1

<P>In previous reports we demonstrated that ginsenosides, active ingredients of Panax ginseng, affect some subsets of voltage-dependent Ca(2+) channels in neuronal cells expressed in Xenopus laevis oocytes. However, the major component(s) of ginseng that affect cloned Ca(2+) channel subtypes such as alpha(1C) (L)-, alpha(1B) (N)-, alpha(1A) (P/Q)-, a1E (R)- and a1G (T) have not been identified. Here, we used the two-microelectrode volt-age clamp technique to characterize the effects of ginsenosides and ginsenoside metabolites on Ba(2+) currents (IBa) in Xenopus oocytes expressing five different Ca(2+) channel subtypes. Exposure to ginseng total saponins (GTS) induced voltage-dependent, dose-dependent and reversible inhibition of the five channel subtypes, with particularly strong inhibition of the a1G-type. Of the various ginsenosides, Rb(1), Rc, Re, Rf, Rg(1), Rg(3), and Rh(2), ginsenoside Rg(3) also inhibited all five channel subtypes and ginsenoside Rh(2) had most effect on the a1C- and a1E-type Ca(2+) channels. Compound K (CK), a protopanaxadiol ginsenoside metabolite, strongly inhibited only the a(1G)-type of Ca(2+) channel, whereas M4, a protopanaxatriol ginsenoside metabolite, had almost no effect on any of the channels. Rg(3), Rh(2), and CK shifted the steady-state activation curves but not the inactivation curves in the depolarizing direction in the alpha(1B)- and alpha(1A)-types. These results reveal that Rg(3), Rh(2) and CK are the major inhibitors of Ca(2+) channels in Panax ginseng, and that they show some Ca(2+) channel selectivity.</P>

Effect of a Pt–ZrO₂ protection layer on the performance and morphology of Pd–Au alloy membrane during H₂S exposure

Lee, Sung-Wook,Oh, Duck-Kyu,Park, Jin-Woo,Lee, Chun-Boo,Lee, Dong-Wook,Park, Jong-Soo,Kim, Sung-Hyun,Hwang, Kyung-Ran Elsevier 2015 JOURNAL OF ALLOYS AND COMPOUNDS Vol.641 No.-

<P><B>Abstract</B></P> <P>We prepared a disc-type Pd–Au alloy membrane, on which a Pt–ZrO<SUB>2</SUB> protection layer was deposited to protect the hydrogen membrane from H<SUB>2</SUB>S poisoning. The effect of the protection layer on the performance and morphology of the Pd–Au alloy membrane during H<SUB>2</SUB>S exposure was investigated. The hydrogen flux did not decrease significantly in the presence of the protection layer, which covered the surface of the membrane. When the membrane with the protection layer was exposed to a mixture of H<SUB>2</SUB>S, the hydrogen flux decreased to 35% of the original value, which is half of the decrease observed with the bare Pd–Au membrane. The hydrogen flux of the poisoned membrane was almost completely recovered after changing back to pure H<SUB>2</SUB> gas. Under harsh conditions, the membrane with the protection layer was found to retain the hydrogen flux and selectivity, while the selectivity of the bare membrane decreased to zero, indicating that it was disintegrated. This means that the Pt–ZrO<SUB>2</SUB> layer prevents direct contact between Pd and H<SUB>2</SUB>S, thus protecting the Pd membrane from poisoning.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Pd-alloy membrane having a protection layer has relatively high resistance to H<SUB>2</SUB>S poisoning. </LI> <LI> Pt–ZrO<SUB>2</SUB> protection layer was prepared using the DC/RF magnetron sputtering system. </LI> <LI> The hydrogen flux did not significantly decreased in the presence of the protection layer. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Hydrogen Production from Methane Steam Reforming in Combustion Heat Assisted Novel Microchannel Reactor with Catalytic Stacking

Lee, Chun-Boo,Lee, Sung-Wook,Lee, Dong-Wook,Ryi, Shin-Kun,Park, Jong-Soo,Kim, Sung-Hyun American Chemical Society 2013 INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH - Vol.52 No.39

<P>In this study, we further investigate the application of an MCR containing a nickel metal catalyst with variable number of stacks for hydrogen production via MSR. Microchannels were contained in the MCR one side of the nickel metal catalyst with variable number of stacks for producing hydrogen to generate the necessary heat for the endothermic MSR and the combustion reaction was performed on the other side of the MCR. The catalyst used in this study for the MSR reaction, which was a prepared Pd[0.1]-Al[0.3]/Ni catalyst. The methane conversion and hydrogen production mole ratio were 94.7% and 9.39 mol h<SUP>–1</SUP>, respectively, and the steam/carbon (S/C) ratio was 3 at 650 °C, GHSV = 10 000 h<SUP>–1</SUP>. The promise of a feasible simplified system for hydrogen production from the MSR was confirmed. If a hydrogen separation membrane is placed between the MSR elements in an MCR, the forward reaction will be preferentially promoted by the rapid removal of the hydrogen produced through the MSR reaction.</P>

Antioxidant activity and inhibitory effect on MMP-1 expression in UVA-irradiated human dermal fibroblasts of the exopolysaccharide produced from submerged culture of Grifola frondosa

Bum-Chun Lee(이범천),Jun-Tae Bae(배준태),Gwan-Sub-Sim(심관섭),Sung-Min Park(박성민),Dong-Hwan Lee(이동환),Hyeong-Bae Pyo(표형배),Tae-Boo Choe(최태부) 한국생물공학회 2004 한국생물공학회 학술대회 Vol.2004 No.10

Anti-oxidative and Photo-protective Effects of Coumarins Isolated from Fraxinus chinensis

Bum-Chun Lee,So Yong Lee,Hwa Jeong Lee,Gwan-Sub Sim,Jin-Hui Kim,Jin-Hwa Kim,조영호,Dong-Hwan Lee,표형배,Tae-Boo Choe,문동철,윤여표,홍진태 대한약학회 2007 Archives of Pharmacal Research Vol.30 No.10

Free radicals and reactive oxygen species (ROS), which are generated by UV irradiation, may cause serious injury to skin cell membranes, DNA and functional proteins. In addition, these agents stimulate the expressions of matrix metalloproteinases (MMPs), which can degrade most components of the extracellular matrix (ECM), including collagen. In order to develop new anti-photoaging agents, five major components from the extract of Fraxinus chinensis extract (FCE) were identified. Two of the major components of FCE were found to be esculin (11.2%) and esculetin (1.9%). FCE (IC50: 50.0 µg/mL 1, 1-diphenyl-2-picrylhydrazyl (DPPH); 19.8 µg/mL, superoxide anion radical) and esculetin (IC50: 2.1 µg/mL DPPH; 0.6 µg/mL, superoxide anion radical) showed strong antioxidative activities. Of the compounds tested, esculetin showed the strongest scavenging activity against DPPH radicals, followed by superoxide anions from the xanthine/xanthine oxidase system. The intracellular ROS scavenging activity showed that oxidation of 5-(6-)-chloromethyl-2', 7'-dichlorodihydrofluorescein diacetate (CMH2DCFDA) was effectively inhibited by esculetin, with potent free radical scavenging activity was also shown in UVB-irradiated human dermal fibroblasts (HDFs). Moreover, treatment of UVA-irradiated HDFs with esculetin resulted in dose-dependent decreases in the expression levels of MMP-1 mRNA and protein. From these results, FCE and one of its components, esculetin, were predicted to be potentially useful as ingredients in cosmetics for protecting against photoaging.

Ceramic barrier coated Pd hydrogen membrane on a porous nickel support

이춘부(Lee, Chun-Boo),이성욱(Lee, Sung-Wook),박진우(Park, Jin-Woo),김광호(Kim, Kwang-Ho),황경란(Hwang, Kyung-Ran),박종수(Park, Jong-Soo),김성현(Kim, Sung-Hyun) 한국신재생에너지학회 2010 한국신재생에너지학회 학술대회논문집 Vol.2010 No.11

A highly performed Pd-based hydrogen membrane has prepared successfully on a modified porous nickel support. The porous nickel support modified by impregnation method of Al(NO₃)₃{cdot}9H₂O (Aldrich Co.) over the nickel powder showed a strong resistance to hydrogen embrittlement and thermal stability. Plasma surface modification treatment was introduced as a pre-treatment process instead of conventional HCl wet activation. Ceramic barrier was coated on the external surface of the prepared nickel supports to prevent intermetallic diffusion and to enhance the affinity between the support and membrane. Palladium and copper were deposited at thicknesses of 4mu}m and 0.5{mu}m, respectively, on a barrier-coated support by DC sputtering process. The permeation measurement was performed in pure hydrogen at 400?C. The single gas permeation of our membrane was two times higher than that of the previous membrane which do not have ceramic barrier.