희석 반응 방식에 의한 제올라이트 박막 합성 연구

김근수,추고연,김태환,성재석,이용택,오숭호,이민수,최호상 한국공업화학회 2003 응용화학 Vol.7 No.1

Zeolite membrane was produced by hydrothermal synthesis on α￣alumina substrate using clear solution method. Zeolite membrane can separate liquid phase reactants like a water/mehtanol system. The compogition ratio of raw materials. 90 Na_2O : 1 Al_2O_3 : 9 SiO_2 : 5760 H_2O was used for preparation of zeolite membrane. The deposition states of zeolite crystal on alumina substrate by change of aging time were analysed through XRD and SEM.

SEQUENCE ANALYSIS AND COMPARISON OF BOVINE α_S1-CASEIN GENOMIC DNA

Lin, C.S.,Huang, M.C.,Choo, K.B.,Tseng, Y.H. Asian Australasian Association of Animal Productio 1993 Animal Bioscience Vol.6 No.4

A phage clone containing the partial ${\alpha}_{S1}$-casein gene was isolated from a bovine genomic library by using mixed probes of ovine ${\alpha}_{S1}$-, ${\beta}$- and ${\kappa}$-casein cDNAs. Restriction enzyme mapping analysis for 14.6 kb revealed that the map was in conflict with the report of Meade et al. (1990), especially in the 3'-end fragment. Sequence analysis of 12.6 kb revealed a high AT/GC ratio (1.64); we have identified eight exon sequences according to the bovine ${\alpha}_{S1}$-casein cDNA sequence. The same exon/intron splice junction sequence was observed between these exons. We suggest that the bovine ${\alpha}_{S1}$-casein gene night contain a minimum of 18 exons and the full length is approximately 18-19 kb.

Characterization of CdS Nanoparticles Embedded in Polyvinyl Alcohol

유동선,하성용,Kim I. G.,Choo M. S.,Kim K. W.,Lee E. S. 한국물리학회 2011 새물리 Vol.61 No.7

CdS nanoparticles embedded in a PVA (polyvinyl alcohol) matrix were prepared and characterized by using cadmium chloride (CdCl₂) and sodium sulfide (Na_2S). When CdCl₂of various molar concentrations was a mixed with a PVA aqueous solution, the -OH groups in PVA acted as coordinating sites for cadmium ion Cd^(2+) aggregations to form PVA-Cd^(2+) composites. The CdS nanoparticles embedded in PVA were successfully grown at these sites by dipping PVA-Cd^(2+) composites into a solution that contained 0.5 mM of S^(2-) ions from Na_2S. The optical band gaps of the nanoparticles were increased from 2.51eV to 2.74 eV by decreasing the molar concentration of CdCl₂from 5 mM to 0.5 mM, indicating that the size of the nanoparticles increased with increasing CdCl₂molar concentration. X-ray diffraction results showed that the CdS nanoparticles were in a cubic phase while their sizes,estimated to be 4.7 nm, 4.8 nm and 5.9 nm for CdCl₂concentrations of 0.7 mM, 1.0 mM and 3.0 mM, respectively, were almost identical to the values calculated by using Brus’s formula. The PL emission spectra of the CdS nanoparticles formed by 0.7 mM of Cd^(2+)showed two peaks, one at 471 nm and the other at 606 nm,which were attributed to the band edge and to surface defects,respectively.

Quercetin-POM (pivaloxymethyl) conjugates: Modulatory activity for P-glycoprotein-based multidrug resistance

Kim, M.K.,Park, K.s.,Choo, H.,Chong, Y. G. Fischer 2015 Phytomedicine Vol.22 No.7

<P>Background: We previously demonstrated that the bioactivity of quercetin could be improved through conjugation with a hydrolysable pivaloxymethyl (POM) group. Purpose: Present study aimed to evaluate MDR (multidrug resistance)-modulatory activity of the quercetin-POM conjugates. Study design/methods: MDR-modulatory activity was determined by measuring cytotoxicity of various anticancer agents to MDR MES-SA/Dx5 cell lines upon combination with the quercetin-POM conjugates. Results: The quercetin-7-O-POM conjugate (7-O-POM-Q) was significantly more potent than quercetin in reversing MDR, which recovered the cytotoxicity of various anticancer agents with EC50 values of 1.1-1.3 mu M. A series of mechanistic studies revealed that 7-O-POM-Q competes with verapamil in binding to the same drug-binding site of the major MDR target, Pgp (P-glycoprotein), and inhibits Pgp-mediated drug efflux with a similar potency as verapamil. The physicochemical properties of 7-O-POM-Q were then evaluated, which confirmed that 7-O-POM-Q has remarkably enhanced cellular uptake and intracellular localization compared with quercetin. Additionally, it is noteworthy that 7-O-POM-Q undergoes slow hydrolysis to quercetin over a prolonged period of time. Conclusion: The quercetin-POM conjugate showed significantly improved MDR-reversing activity compared with quercetin, which could be attributed to its capacity to maintain high intracellular concentrations. (C) 2015 Elsevier GmbH. All rights reserved.</P>

희석반응 방식을 이용한 NaA형 미립 제올라이트 박막 제조 연구

김근수,김태환,추고연,이민수,이용택 한국공업화학회 2004 응용화학 Vol.8 No.1

In this work, zeolite membranes were prepared using a conventional hydrothermal method and clear solution method followed by characterization of permeation and separation factor. Especially submicron size zeolite powder was used as seed material on the alumina support and the temperature of synthesis was fixed at 90?. It was confirmed that the prepared zeolite membrane using clear solution method was more uniform compared with the hydrothermal synthesis. The zeolite membrane thickness of ca. 10㎛was obtained.

국내산 원유에 대한 식품위생학적 연구

이원창,추범수,김순재,이상목,송재옹 한국수의공중보건학회 1985 예방수의학회지 Vol.9 No.1

10 Gb/s 급 광통신용 1.55 ㎛ SI - PBH DFB - LD의 제작 및 특성연구

김형문(Hyung M. Kim),김정수(Jeong S. Kim),오대곤(Dae K. Oh),주홍로(Heung R. Choo),박성수(Seung S. Park),송민규(Min K. Song),곽봉신(Bong S. Kwack),김홍만(Hong M. Kim),편광의(Kwang E. Pyun) 한국광학회 1997 한국광학회지 Vol.8 No.4

2단계 메사 식각 공정과 유기 금속 화학 증착방법으로 높은 비저항을 갖는 Fe-도핑된 반절연 InP층의 전류 차단층을 갖는 10 Gb/s 광통신용 초고속 1.55 ㎛ 궤환형 반도체 레이저 다이오드를 제작하였다. 제작된 DFB-LD의 특성은 발진 임계전류 ~15 ㎃, slope efficiency ~0.13 ㎽/㎃, 동 저항 ~6.0 Ω이었고, 발진 파장은 1.546 ㎛이며, 6 Ith 까지의 전류에도 인접 모우드 억압비, SMSR>40㏈ 이상 (CW 상태) 으로써 안정된 단일 모우드 동작을 보였다. DFB-LD의 소신호 주파수 특성으로 27 ㎃의 작은 구동전류에서 이미 -3㏈ 대역폭이 10 ㎓에 도달하였음을 보여주었고, 또한 최대 -3 ㏈ 대역폭으로 구동 전류 90 ㎃에서 ~18 ㎓까지 얻는 우수한 소신호 주파수 특성을 보여주었다. 10 Gb/s DFB-LD 모듈 전송시험에 있어서, 1.55 ㎛ 파장의 레이저 다이오드 모듈로 일반 단일모우드 광섬유와 분산천이 광섬유에 대해서 전송시험한 결과 에러평탄면 (error floor) 없이 각각 10 ㎞, 80 ㎞를 전송할 수 있었다. We fabricated the high speed 1.55 ㎛ distributed feedback laser diodes (DFB-LD) using both two-step mesa etching process and semi-insulating InP current blocking layers. The devices characteristics were threshold current of ~15 ㎃, slope efficiency of ~0.13 ㎽/㎃, and dynamic resistance of ~6.0 Ω, with as-cleaved facets. The fabricated DFB-LD showed the single longitudinal mode with more than 40 dB up to 6 I_(th) (CW condition), emitting at the wavelength of 1.546 ㎛. The -3 dB bandwidth was > 10 ㎓ at the driving current of 27 ㎃, and the maximum -3 dB bandwidth was ~18 ㎓ at 90 ㎃ current, showing the superior frequency response of SI-PBH DFB-LD. In the 10 Gb/s transmission experiment for 1.55 ㎛ DFB-LD module, maximum 10 ㎞ of single mode fiber (SMF) or 80 ㎞ of dispersion shifted fiber (DSF) could be transmitted with error free.

Randomized Trial of Stents Versus Bypass Surgery for Left Main Coronary Artery Disease

Ahn, J.M.,Roh, J.H.,Kim, Y.H.,Park, D.W.,Yun, S.C.,Lee, P.H.,Chang, M.,Park, H.W.,Lee, S.W.,Lee, C.W.,Park, S.W.,Choo, S.J.,Chung, C.,Lee, J.,Lim, D.S.,Rha, S.W.,Lee, S.G.,Gwon, H.C.,Kim, H.S.,Chae, I Elsevier Biomedical 2015 JOURNAL OF THE AMERICAN COLLEGE OF CARDIOLOGY - Vol.65 No.20

<P>BACKGROUND In a previous randomized trial, we found that percutaneous coronary intervention (PCI) was not inferior to coronary artery bypass grafting (CABG) for the treatment of unprotected left main coronary artery stenosis at 1 year. OBJECTIVES This study sought to determine the 5-year outcomes of PCI compared with CABG for the treatment of unprotected left main coronary artery stenosis. METHODS We randomly assigned 600 patients with unprotected left main coronary artery stenosis to undergo PCI with a sirolimus-eluting stent (n = 300) or CABG (n = 300). The primary endpoint was a major adverse cardiac or cerebrovascular event (MACCE: a composite of death from any cause, myocardial infarction, stroke, or ischemia-driven target vessel revascularization) and compared on an intention-to-treat basis. RESULTS At 5 years, MACCE occurred in 52 patients in the PCI group and 42 patients in the CABG group (cumulative event rates of 17.5% and 14.3%, respectively; hazard ratio [HR]: 1.27; 95% confidence interval [CI]: 0.84 to 1.90; p = 0.26). The 2 groups did not differ significantly in terms of death from any cause, myocardial infarction, or stroke as well as their composite (8.4% and 9.6%; HR, 0.89; 95% CI, 0.52 to 1.52; p = 0.66). Ischemia-driven target vessel revascularization occurred more frequently in the PCI group than in the CABG group (11.4% and 5.5%, respectively; HR: 2.11; 95% CI: 1.16 to 3.84; p = 0.012). CONCLUSIONS During 5 years of follow-up, our study did not show significant difference regarding the rate of MACCE between patients who underwent PCI with a sirolimus-eluting stent and those who underwent CABG. However, considering the limited power of our study, our results should be interpreted with caution. (C) 2015 by the American College of Cardiology Foundation.</P>

AN ELEMENTARY PROOF OF THE EXISTENCE OF A POSITIVE EQUILIBRIUM IN REACTION NETWORKS

S. M. Choo 한국전산응용수학회 2010 Journal of applied mathematics & informatics Vol.28 No.5

It is interesting to know the behavior of a network from its structure. One interesting topic is to find a relation between the existence of a positive equilibrium of the reaction network and its structure. One approach to study this topic is using the concept of deficiency. In this work, we develop an algorithm and show an elementary proof of the relation based on the algorithm and deficiency.

ASYMTOTIC BEHAVIOUR OF THE VISCOUS CAHN-HILLIARD EQUATION

Choo, S.M.,Chung, S.K. 한국전산응용수학회 2003 Journal of applied mathematics & informatics Vol.11 No.1

Analytical solutions for the viscous Cahn-Hilliard equation are considered. Existence and uniqueness of the solution are shown. The exponential decay of the solution in H$^2$-norm, which is an improvement of the result in Elliott and Zheng[5]. We also compare the early stages of evolution of the viscous Cahn-Hilliard equation with that of the Cahn-Hilliard equation, which has been given as an open question in Novick-Cohen[8].