Effect of oxygen partial pressure on the morphology and properties of Ce doped YBCO films fabricated by a MOCVD process

Kim, Y.H.,Kim, C.J.,Jun, B.H.,Sung, T.H.,Han, Y.H.,Han, S.C.,Paik, H.J.,Youn, J.S.,No, K. North-Holland 2009 Physica. C, Superconductivity Vol.469 No.15

Rare-earth (RE) (e.g. Sm, Dy, Ce, etc.) doping has been widely investigated to improve critical current density (J<SUB>c</SUB>) of YBa<SUB>2</SUB>Cu<SUB>3</SUB>O<SUB>7-X</SUB> (YBCO) coated conductors (CC). Oxygen partial pressure is known to be a key parameter in terms of affecting the J<SUB>c</SUB> of YBCO films. In this work, the effect of oxygen partial pressure on the microstructure and J<SUB>c</SUB> of a Ce doped YBCO film was examined. Ce doped YBCO films were deposited on (100) SrTiO<SUB>3</SUB> (STO) single crystal substrates at oxygen partial pressures of 2.5, 5.0, and 10.0Torr using a metal organic chemical vapor deposition (MOCVD) method. Due to the enhanced migration of surface adatoms under reduced oxygen partial pressure, a 1wt% Ce doped YBCO film had a stoichiometric, dense surface. In addition, the zero-field J<SUB>c</SUB> (at 77K) of the 1wt% Ce doped YBCO film deposited at reduced oxygen partial pressure was increased. Irrespective of the amount of Ce, the Ce doped YBCO film showed an increased zero-field J<SUB>c</SUB> (at 77K) under reduced oxygen partial pressure.

Improvement of the superconducting properties of an infiltrated YBCO bulk superconductor by a BaCeO₃ addition

Mahmood, A.,Park, S.D.,Jun, B.H.,Youn, J.S.,Han, Y.H.,Sung, T.H.,Kim, C.J. North-Holland 2009 Physica. C, Superconductivity Vol.469 No.15

Single grain YBa<SUB>2</SUB>Cu<SUB>3</SUB>O<SUB>7-x</SUB> (Y123) bulk superconductors with Y<SUB>2</SUB>BaCuO<SUB>5</SUB> (Y211) and various amounts of BaCeO<SUB>3</SUB> (5-45wt.% by an increment of 10wt.%) were fabricated by a seeded infiltration process. The addition of BaCeO<SUB>3</SUB> was found to be effective for a modification of the microstructure and an improvement of the superconducting properties. The refinement effect for Y211 particles within an entire superconducting YBa<SUB>2</SUB>Cu<SUB>3</SUB>O<SUB>7-x</SUB> (Y123) matrix was achieved by BaCeO<SUB>3</SUB> additions. The critical current density (J<SUB>c</SUB>) values were increased as the BaCeO<SUB>3</SUB> contents were increased (maximum J<SUB>c</SUB> at 35wt.% BaCeO<SUB>3</SUB> addition). The J<SUB>c</SUB> improvement by BaCeO<SUB>3</SUB> additions might be due to the microstructure modifications associated with the finely distributed Y211 and BaCeO<SUB>3</SUB> particles. With the addition of BaCeO<SUB>3</SUB> the onset T<SUB>c</SUB> values decreased slightly, indicating highly limited Ce substitution for Y site. It can be concluded that the BaCeO<SUB>3</SUB> addition has a beneficial effect on the morphology, the size and the distribution of the Y211 inclusions and the microstructure regarding pinning improvement.

Gender differences in coronary plaque components in patients with acute coronary syndrome: Virtual histology-intravascular ultrasound analysis

Hong, Y.J.,Jeong, M.H.,Choi, Y.H.,Ma, E.H.,Cho, S.H.,Ko, J.S.,Lee, M.G.,Park, K.H.,Sim, D.S.,Yoon, N.S.,Youn, H.J.,Kim, K.H.,Park, H.W.,Kim, J.H.,Ahn, Y.,Cho, J.G.,Park, J.C.,Kang, J.C. Japanese College of Cardiology 2010 Journal of cardiology Vol.56 No.2

Background: The aim of this study was to evaluate the gender differences in plaque components in acute coronary syndrome (ACS) patients. Methods: We used virtual histology-intravascular ultrasound to evaluate the plaque components in culprit lesions in 362 ACS patients (254 men, 108 women). Results: Women were more likely to be diabetic (34% vs 23%, p=0.030), had greater percentage necrotic core (%NC) volume (19.0+/-12.7% vs 16.8+/-11.9%, p=0.040), and had trends toward higher high-sensitivity C-reactive protein (hs-CRP) (0.85+/-1.28mg/dl vs 0.53+/-0.48mg/dl, p=0.063), and higher incidence of thin-cap fibroatheroma (TCFA) (62% vs 52%, p=0.078) compared with men. %NC volume was significantly greater in diabetic patients compared with nondiabetic patients (20.4+/-10.2% vs 16.0+/-8.9%, p<0.001) and was significantly greater in patients with elevated hs-CRP (>=0.2mg/dl) compared with those with normal hs-CRP (<0.2mg/dl) (18.8+/-8.9% vs 16.6+/-9.7%, p=0.021). However, there were no differences in plaque components between diabetic women and men, and between women and men with elevated hs-CRP levels. Diabetes [odds ratio (OR): 2.44, 95% confidence interval (CI): 1.35-3.82, p=0.003] and hs-CRP (OR: 1.54, 95% CI: 1.08-2.65, p=0.032), but not female gender, were the independent predictors of TCFA. Conclusions: Although it seems likely that female ACS patients have more vulnerable plaque components compared with male ACS patients, these findings may result not from true gender differences in plaque components but higher prevalence of diabetes and hs-CRP elevation in women.

AS-275: Relation Between High-Sensitivity C-Reactive Protein and Coronary Plaque Components in Patients with Acute Coronary Syndrome: Virtual Histology-Intravascular Ultrasound Analysis

Hong, Y.J.,Jeong, M.H.,Choi, Y.H.,Ko, J.S.,Lee, M.G.,Kang, W.Y.,Lee, S.E.,Kim, S.H.,Sim, D.S.,Park, K.H.,Yoon, N.S.,Youn, H.J.,Kim, K.H.,Park, H.W.,Kim, J.H.,Ahn, Y.,Cho, J.G.,Park, J.C.,Kang, J.C. Cahners Pub. Co., etc.] ; Elsevier Science Ltd 2009 The American Journal of Cardiology Vol.103 No.9

Age-related differences in virtual histology-intravascular ultrasound findings in patients with coronary artery disease

Hong, Y.J.,Jeong, M.H.,Choi, Y.H.,Ma, E.H.,Ko, J.S.,Lee, M.G.,Park, K.H.,Sim, D.S.,Yoon, N.S.,Youn, H.J.,Kim, K.H.,Park, H.W.,Kim, J.H.,Ahn, Y.,Cho, J.G.,Park, J.C.,Kang, J.C. Japanese College of Cardiology 2010 Journal of cardiology Vol.55 No.2

Background: We assessed the age-related differences in pre-intervention virtual histology-intravascular ultrasound (VH-IVUS) findings at target lesion sites in patients with coronary artery disease. Methods: A total of 553 patients who underwent pre-intervention VH-IVUS imaging were grouped according to age: non-elderly (@?70 years, n=429) and elderly (>70 years, n=124); 191 had stable angina and 362 acute coronary syndrome. VH-IVUS classified the tissue into: fibrotic, fibro-fatty, dense calcium (DC), and necrotic core (NC). Results: Overall, the absolute and percent volumes of DC (11.0+/-11.0mm<SUP>3</SUP> vs. 9.7+/-11.9mm<SUP>3</SUP>, P=0.033; 11.7+/-8.1% vs. 9.8+/-7.2%, P=0.014, respectively) and NC (18.5+/-17.6mm<SUP>3</SUP> vs. 16.6+/-18.9mm<SUP>3</SUP>, P=0.020; 18.8+/-8.8% vs. 16.5+/-9.3%, P=0.026, respectively) were significantly greater in the elderly than in the non-elderly. In stable angina patients, the absolute and percent volumes of DC (10.4+/-9.9mm<SUP>3</SUP> vs. 7.2+/-7.6mm<SUP>3</SUP>, P=0.022; 13.4+/-10.0% vs. 9.2+/-6.5%, P=0.011, respectively) and NC (14.8+/-11.2mm<SUP>3</SUP> vs. 12.0+/-11.9mm<SUP>3</SUP>, P=0.035; 19.6+/-8.8% vs. 15.5+/-8.4%, P=0.006, respectively) were significantly greater in the elderly. However, in acute coronary syndrome patients, there were no significant differences in absolute and percent volumes of DC (11.4+/-11.6mm<SUP>3</SUP> vs. 10.9+/-13.4mm<SUP>3</SUP>, P=0.8; 10.7+/-6.5% vs. 10.1+/-7.5%, P=0.5, respectively) and NC (24.1+/-20.3mm<SUP>3</SUP> vs. 23.9+/-21.2mm<SUP>3</SUP>, P=0.9; 22.0+/-8.8% vs. 21.3+/-9.6%, P=0.6, respectively) between the elderly and non-elderly groups. Myocardial infarction (OR: 2.56, 95% CI: 1.45-4.12, P=0.003), diabetes mellitus (OR: 2.23, 95% CI: 1.30-3.53, P=0.009), and high-sensitivity C-reactive protein (OR: 1.44, 95% CI: 1.06-2.45, P=0.042), but not age, were independent predictors of percent NC volume >20% in lesion site. Conclusions: Myocardial infarction, diabetes mellitus, and high-sensitivity C-reactive protein, but not age, were associated with NC-rich lesions. Clinical presentation, risk factors, and inflammatory status, but not age, are important factors for plaque components.

Carbenoxolone prevents the development of fatty liver in C57BL/6-Lep ^ob/ob mice via the inhibition of sterol regulatory element binding protein-1c activity and apoptosis

Dal Rhee, S.,Kim, C.H.,Seon Park, J.,Hoon Jung, W.,Bum Park, S.,Youn Kim, H.,Hwan Bae, G.,Jan Kim, T.,Young Kim, K. North-Holland ; Elsevier Science Ltd 2012 european journal of pharmacology Vol.691 No.1

Carbenoxolone is the 3-hemisuccinate of glycyrrhetinic acid, the active principal of licorice (Glycyrrhiza glabra). It was reported that carbenoxolone improved glucose tolerance with increased insulin sensitivity in mice with high fat diet-induced obesity. In the present study, we elucidated the protective effect of carbenoxolone in fatty liver animal models of C57BL/6-Lep<SUP>ob/ob</SUP> mice through inhibition of hepatic lipogenesis and apoptosis. In addition, the potential mechanisms by which carbenoxolone could exert such protection were elucidated. Carbenoxolone was daily administrated by gavage for 28 days in C57BL/6 and C57BL/6-Lep<SUP>ob/ob</SUP> mice. Carbenoxolone prevented the plasma triglyceride and free fatty acid accumulation associated with the reduction of the expression of sterol regulatory element binding protein-1c, liver X receptor, fatty acid synthase and acethyl-CoA carboxylase in the livers of C57BL/6-Lep<SUP>ob/ob</SUP> mice. Carbenoxolone also prevented hepatic injury through anti-apoptotic action in the livers of C57BL/6-Lep<SUP>ob/ob</SUP> mice, accompanied by increased Bcl-2 expression and suppressed Bax and cytochrome c expression. As a mechanism, increased inflammatory cytokine expressions were inhibited by carbenoxolone in the fatty livers of C57BL/6-Lep<SUP>ob/ob</SUP> mice. Furthermore, carbenoxolone inhibited free fatty acid (oleate/palmitate) induced reactive oxygen species formation and reversed free fatty acid induced mitochondrial membrane depolarization in HepG2 cells. Carbenoxolone prevents the development of fatty liver by inhibiting sterol regulatory element binding protein-1c expression and activity with an anti-apoptotic mechanism via the inhibition of inflammatory cytokine and reactive oxygen species formation in the livers of C57BL/6-Lep<SUP>ob/ob</SUP> mice. It is suggested that carbenoxolone prevents the development and progression of fatty liver disease in patients with insulin resistance.

Enhanced I-V Characteristics in InGaN/GaN Multi-Quantum-Well Light-Emitting Diode with an n-type Interface Layer

C. S. Kim,B. K. Lee,홍창희,D. S. Kang,H. J. Lee,H. K. Cho,H. S. Youn,R. J. Choi,S. J. Bae,한윤봉 한국물리학회 2003 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.42 No.III

The effect of an n-type interface layer between n$^+$-GaN layer and InGaN/GaN multi-quantum-well (MQW) in a blue light-emitting diode (LED) on device performance was investigated by current-voltage (I-V) and output power measurements. Two different graded interface layers were tested on Si-doped n$^+$-GaN layer with graded growth rate and Si-doping for atomic force microscopy (AFM) and capacitance-voltage (C-V). Experimental results indicate that the characteristics of the LED with the graded interface layer exhibited a lower operating voltage and a better reverse voltage, as well as a higher output power, compared to that of conventional LEDs. This could be tentatively attributed to enhanced current injection and/or current spreading into the MQWs resulting from smoothed band profile and surface morphology of the interface by modulated Si-doping and graded growth rate.

Characteristics of InGaN/GaN Multi-Quantum-Well Light-Emitting Diodes with Various Growth Temperatures of p-GaN Layers

C. S. Kim,B. K. Lee,홍창희,D. S. Kang,서은경,H. J. Lee,H. K. Cho,H. S. Youn,R. J. Choi,S. J. Bae,한윤봉 한국물리학회 2003 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.42 No.III

InGaN/GaN multi-quantum-well (MQW) blue light-emitting diodes (LEDs) with various growth temperatures of p-GaN layers were grown by metal-organic chemical vapor deposition (MOCVD) and their characteristics were evaluated by current-voltage (I-V) and output power measurements. The growth temperature of the p-GaN layer strongly affects I-V characteristics and output power in the LEDs. Operating voltage at 20 mA decreases slightly with increasing growth temperature of p-GaN layer, whereas output power increases. The results of capacitance-voltage (C-V) measurements reveal that acceptor concentration exhibits a strong tendency to increase output power with the growth temperature.

Particle distribution in melt-processed Y_1.5 Ba₂Cu₃O_x superconductors with BaCeO₃ addition

Youn, J.S.,No, K.,Kim, Y.H.,Mahmood, A.,Jun, B.H.,Han, Y.H.,Sung, T.H.,Kim, C.J. North-Holland 2009 Physica. C, Superconductivity Vol.469 No.15

To understand the effect of BaCeO<SUB>3</SUB> on a Y<SUB>2</SUB>BaCuO<SUB>5</SUB> (Y211) distribution, Y<SUB>1.5</SUB>Ba<SUB>2</SUB>Cu<SUB>3</SUB>O<SUB>x</SUB> (Y1.5) superconductors with/without 1wt.% BaCeO<SUB>3</SUB> additions were prepared by a top-seeded melt-textured growth (TSMG) process. Two different BaCeO<SUB>3</SUB> powders (as-synthesized (coarse powder) and an attrition-milled (fine powder)) were used and the size effect was compared with that obtained from a Y1.5 sample with no addition. A refinement of the Y211 particles was achieved for both the as-synthesized and attrition-milled BaCeO<SUB>3</SUB> additions. The distribution of the Y211 particles was most uniform in the Y1.5 sample prepared with the attrition-milled BaCeO<SUB>3</SUB> powder due to the reduced size of the Y211-free regions by the fine size BaCeO<SUB>3</SUB> addition. The highest J<SUB>c</SUB> was achieved in the Y1.5 sample prepared with the attrition-milled BaCeO<SUB>3</SUB> powder. The J<SUB>c</SUB> result agreed well with the microstructure variations by the addition of BaCeO<SUB>3</SUB> powders.

문학반응이론에 의한 보건의학기술계열 국가시험개선방안에 관한 연구

이창규,이승관,조경진,박종성,정수경,유병서,박상숙,윤효숙,황선철,문경환,김정민,함용운,김지환,임국환,김영순,윤경희,황성준 高麗大學校 倂設 保健大學 保健科學硏究所 1998 保健科學論集 Vol.24 No.1

The nationally-governed examinations for certification of allied health professions in Korea have been continued for thirty three years. During that time, there were a lot of managerial improvements in carrying out the examinations, for example, the looking-over the papers converted from manual method to computerized one. Nevertheless, the overall aspects of item management in the national examinations are still remained as obsolete style. In some developed countries they have already tried or adopted computerized system in making questions, executing item analysis, developing item banking, and in overall management of examinations, looking over papers for their national licensure examinations, and have established good reputations. Since the National Health Personnel Licensing Examination Board was established in 1998, now we can expect there would be a lots of improvements in the managerial systems and organizational structures associated with the national licensing examinations suggesting followings. 1. The contents and scope of the licensing examinations based on job analysis should be announced publicaly. 2. Items should be developed based on the scopes and contents of job characteristics. 3. All the developed items for the licensing examinations should be tested quantitatively prior to banking items. 4. All the parameters of the stored items should be fully estimated through item response theory. 5. All the efforts should be given in order to execute the examinations in individual residential areas on behalf of every examinee. 6. To the licensing examination system the Computerized Adaptive Testing system should be introduced in order to enhance the efficiencies. 7. Security enhancement on the stored items should be reminded in order to prevent leaking out the banking items. 8. Much more improvements should be made for the proper job evaluations. 9. Every efforts should be given to prevent cheatings encountable during the examinations. 10. Make the best of professional volunteers from the various fields in the execution of licensing examinations. 11. Consider a new system in that examinations can be executed twice or more in a year. 12. The current methods of presiding over the examinations should be replaced by a more reasonable one. 13. The results of the examinations should be announced as soon as possible in order not to prolong the examinees' unemployment periods. 14. The National Health Personnel Licensing Examination Board should try to rationalize the management keeping step with the information-oriented society.