Dependence of the exchange bias and coercivity of [Pd/Ferromagnet]_N/FeMn multilayers on the stack number N

Joo, H.W.,Lee, M.S.,Kim, S.W.,Kim, S.S.,Lee, J.Y.,Baek, J.Y.,You, C.-Y.,Lee, K.A.,Rhee, J.R.,Lee, S.S.,Hwang, D.G. IEEE 2006 IEEE transactions on magnetics Vol.42 No.10

The dependencies of the stack number N on perpendicular exchange-biasing (H<SUB>ex</SUB>) and coercivity H<SUB>c</SUB>) in [Pd/Co]<SUB>N</SUB> and [Pd/Co (or CoFe)]<SUB>N</SUB>/FeMn multilayers were investigated. With the help of the careful designs of layer structures, a series of samples whose surface anisotropies have the linear function N was prepared with constant bulk anisotropies. From the experimental data obtained, it was found that H<SUB>ex</SUB> does not depend on the surface anisotropy, while H<SUB>c</SUB> shows a strong dependence. Therefore, it is possible to tailor wide ranges of H<SUB>c</SUB> (300-600 Oe) without varying H<SUB>ex</SUB>(∼200 Oe) through the single control parameter stack number N.

Effect of Curing Time on the Physicochemical and Sensory Properties of Beef Jerky Replaced Salt with Soy Sauce, Red Pepper Paste and Soybean Paste

Lim, H.J.,Kim, G.D.,Jung, E.Y.,Seo, H.W.,Joo, S.T.,Jin, S.K.,Yang, H.S. Asian Australasian Association of Animal Productio 2014 Animal Bioscience Vol.27 No.8

This study was done to investigate the quality properties of beef jerky with soy sauce, red pepper paste, and soybean paste replacing salt. Sliced beef samples were cured in salt (control), soy sauce, red pepper paste, and soybean paste for 24 or 48 h and then dried at $70^{\circ}C$ for 8 h. Treatments showed higher final moisture content and lower $Na^+$ concentration than the control after drying for 8 h. The lightness and shear force values were lower in all treatment samples than in the control during 48 h of curing time. In particular, lower lipid oxidation was found in the jerky cured with red pepper paste than in the control. Sensory evaluation showed that color, flavor, and tenderness of jerky samples were improved by replacing salt with soy sauce, red pepper paste and soybean paste, and higher likeability scores of the beef jerky were obtained among those treatments after 48 h of curing time.

Effects of nano-carbon doping and sintering temperature on microstructure and properties of MgB₂

Lim, J.H.,Shim, J.H.,Choi, J.H.,Park, J.H.,Kim, W.,Joo, J.,Kim, C.J. North-Holland 2009 Physica. C, Superconductivity Vol.469 No.15

We fabricated nano-carbon (NC) doped MgB<SUB>2</SUB> bulks using an in situ process in order to improve the critical current density (J<SUB>c</SUB>) under a high magnetic field and evaluated the correlated effects of the doped carbon content and sintering temperature on the phase formation, microstructure and critical properties. MgB<SUB>2-x</SUB>C<SUB>x</SUB> bulks with x=0 and 0.05 were fabricated by pressing the powder into pellets and sintering at 800<SUP>o</SUP>C, 900<SUP>o</SUP>C, or 1000<SUP>o</SUP>C for 30min. We observed that NC was an effective dopant for MgB<SUB>2</SUB> and that part of it was incorporated into the MgB<SUB>2</SUB> while the other part remained (undoped), which reduced the grain size. The actual C content was estimated to be 68-90% of the nominal content. The NC doped samples exhibited lower T<SUB>c</SUB> values and better J<SUB>c</SUB>(B) behavior than the undoped samples. The doped sample sintered at 900<SUP>o</SUP>C showed the highest J<SUB>c</SUB> value due to its high doping level, small amount of second phase, and fine grains. On the other hand, the J<SUB>c</SUB> was decreased at a sintering temperature of 1000<SUP>o</SUP>C as a result of the formation of MgB<SUB>4</SUB> phase.

An outbreak of highly pathogenic H5N1 avian influenza in Korea, 2008

Kim, H.R.,Park, C.K.,Lee, Y.J.,Woo, G.H.,Lee, K.K.,Oem, J.K.,Kim, S.H.,Jean, Y.H.,Bae, Y.C.,Yoon, S.S.,Roh, I.S.,Jeong, O.M.,Kim, H.Y.,Choi, J.S.,Byun, J.W.,Song, Y.K.,Kwon, J.H.,Joo, Y.S. Elsevier Scientific Pub. Co 2010 Veterinary microbiology Vol.141 No.3

In spite of intensive surveillance programs for the control of HPAI, an outbreak of highly pathogenic avian influenza (HPAI) H5N1 in Korea in April 2008 caused serious damage to poultry farms, as did previous outbreaks in 2003/2004 and 2006/2007. Six viruses were selected from the Korean 2008 isolates for genetic analysis, and all eight gene segments from each of the influenza viruses were sequenced. A phylogenetic analysis showed that all of the viruses were of the same virus type and that the hemagglutinin (HA) gene was clustered with that of clade 2.3.2 viruses. However, the internal and neuraminidase (NA) genes were closely related to those of the clade 2.3.4 viruses (recent human and bird isolates from Southeast Asia).

여자 대학생의 저출산에 대한 인식 : 서울 지역 중심으로

김연주,김주예,김혜,민지유,박현영,이송,이혜심,주연진,최지희,함연화,강숙정,김부연,김윤정 이화여자대학교 간호과학대학 2019 이화간호학회지 Vol.- No.53

Purpose: The purpose of this study is to understand the perception of low birth rate within female college students. Methods: After obtaining approval from online community and several acquaintance, data were collected from August 10 to September 11. A total of eight students participated in the study. Semi-structured in-depth interview were conducted and the data subsequently analyzed. Results: This study extracted three themes: Fragmentary perception about low birth rate limited to social level problem; Avoidance about sacrifice from delivery and Lack of effectiveness in fertility incentives of present government. Conclusion: This study is meaningful that can explore the perception about low birth rates of female college students who are the subjects of future birth. They recognize low birth rates as a social problem, but do not recognize as individual problem. In addition, this study was able to identify the participants' perception of the low birth rate. It can be suggested as meaningful opinion for some follow-up study.

Combustion stability limits and NO_x emissions of nonpremixed ammonia-substituted hydrogen-air flames

Um, D.H.,Joo, J.M.,Lee, S.,Kwon, O.C. Pergamon Press ; Elsevier Science Ltd 2013 INTERNATIONAL JOURNAL OF HYDROGEN ENERGY - Vol.38 No.34

The combustion stability (extinction) limits and nitrogen oxide (NO<SUB>x</SUB>) emissions of nonpremixed ammonia (NH<SUB>3</SUB>)-hydrogen (H<SUB>2</SUB>)-air flames at normal temperature and pressure are studied to evaluate the potential of partial NH<SUB>3</SUB> substitution for improving the safety of H<SUB>2</SUB> use and to provide a database for the nonpremixed NH<SUB>3</SUB>-substituted H<SUB>2</SUB>-air flames. Considering coflow nonpremixed NH<SUB>3</SUB>-H<SUB>2</SUB>-air flames for a wide range of fuel and coflow air injection velocities (V<SUB>fuel</SUB> and V<SUB>coflow</SUB>) and the extent of NH<SUB>3</SUB> substitution, the effects of NH<SUB>3</SUB> substitution on the stability limits and NO<SUB>x</SUB> emissions of the NH<SUB>3</SUB>-H<SUB>2</SUB>-air flames are experimentally determined, while the nonpremixed NH<SUB>3</SUB>-H<SUB>2</SUB>-air flame structure is computationally predicted using a detailed reaction mechanism. Results show significant reduction in the stability limits and unremarkable increase in the NO<SUB>x</SUB> emission index for enhanced NH<SUB>3</SUB> substitution, supporting the potential of NH<SUB>3</SUB> as an effective, carbon-free additive in nonpremixed H<SUB>2</SUB>-air flames. With increasing V<SUB>coflow</SUB> the NO<SUB>x</SUB> emission index decreases, while with increasing V<SUB>fuel</SUB> it decreases and then increases due to the recirculation of burned gas and the reduced radiant heat losses, respectively. Given V<SUB>coflow</SUB>/V<SUB>fuel</SUB> the flame length increases with enhanced NH<SUB>3</SUB> substitution since more air is needed for reaction stoichiometry. The predicted flame structure shows that NH<SUB>3</SUB> is consumed more upstream than H<SUB>2</SUB> due to the difference between their diffusivities in air.

Design of the RAON Accelerator Systems

전동오,I. S. Hong,H. J. Kim,J. W. Kim,R. M. Bodenstein,차혁진,S. J. Choi,최숙,O. R. Choi,H. Do,B. H. Choi,C. J. Choi,J. Han,W. K. Han,M. O. Hyun,H. Jang,J. D. Joo,M. J. Joung,H. C. Jung,Y. C. Jung,김도균,E. Kim 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.65 No.7

The RAON is the name of the heavy ion accelerator facility under construction in Korea thatincludes the In-flight Fragment (IF) and Isotope Separation On-Line (ISOL) facilities to supportcutting-edge research in various science fields. The superconducting linac is the driver for the IFfacility that can accelerate beams from proton to uranium with 200 MeV/u, 400 kW (for uraniumbeam). A 70-MeV, 1-mA H− cyclotron is the driver for the ISOL facility and is followed by apost-accelerator consisting of s superconducting linac that can accelerate rare-isotope (RI) beamsand deliver them to experimental halls. These facilities provide high-intensity stable ion and rareisotope (RI) beams for domestic and international users. In this paper, design and prototypingefforts for the RAON accelerator systems are presented.

Effect of boron milling on phase formation and critical current density of MgB₂ bulk superconductors

Kang, M.O.,Joo, J.,Jun, B.H.,Park, S.D.,Kim, C.S.,Kim, C.J. The Korea Institute of Applied Superconductivity a 2019 한국초전도저온공학회논문지 Vol.21 No.1

This study was carried out to investigate the effect of milling of boron (B), which is one of raw materials of $MgB_2$, on the critical current density ($J_c$) of $MgB_2$. B powder used in this study is semi-amorphous B (Pavezyum, Turkey, 97% purity, 1 micron). The size of B powder was reduced by planetary milling using $ZrO_2$ balls (a diameter of 2 mm). The B powder and balls with a ratio of 1:20 were charged in a ceramic jar and then the jar was filled with toluene. The milling time was varied from 0 to 8 h. The milled B powders were mixed with Mg powder in the composition of (Mg+2B), and the powder mixtures were uniaxially pressed at 3 tons. The powder compacts were heat-treated at $700^{\circ}C$ for 1 h in flowing argon gas. Powder X-ray diffraction and FWHM (Full width at half maximum) were used to analyze the phase formation and crystallinity of $MgB_2$. The superconducting transition temperature ($T_c$) and $J_c$ of $MgB_2$ were measured using a magnetic property measurement system (MPMS). It was found that $B_2O_3$ was formed by B milling and the subsequent drying process, and the volume fraction of $B_2O_3$ increased as milling time increased. The $T_c$ of $MgB_2$ decreased with increasing milling time, which was explained in terms of the decreased volume fraction of $MgB_2$, the line broadening of $MgB_2$ peaks and the formation of $B_2O_3$. The $J_c$ at 5 K increased with increasing milling time. The $J_c$ increase is more remarkable at the magnetic field higher than 3 T. The $J_c$ at 5 K and 4 T was the highest as $4.37{\times}10^4A/cm^2$ when milling time was 2 h. The $J_c$ at 20 K also increased with increasing milling time. However, The $J_c$ of the samples with the prolonged milling for 6 and 8 h were lower than that of the non-milled sample.

O-free polyacrylonitrile doping to improve the J_c(B) and H_c2 of MgB₂ wires

Hwang, S.M.,Sung, K.,Choi, J.H.,Kim, W.,Joo, J.,Lim, J.H.,Kim, C.J.,Park, Y.S.,Kim, D.H. North-Holland 2010 Physica. C, Superconductivity Vol.470 No.20

We selected polyacrylonitrile (PAN, -[C<SUB>3</SUB>H<SUB>3</SUB>N]-) as an O-free organic dopant and fabricated C-doped MgB<SUB>2</SUB> wires by in situ and powder-in-tube techniques. 0-5 wt.% PAN powders were uniformly mixed with B powder using a liquid mixing method. The precursor powders were mixed with Mg powder, filled into Fe tubes, and then drawn into wires. Sintering was performed at 900<SUP>o</SUP>C for 1h in a flowing Ar gas. The PAN doping decreased the critical temperature (T<SUB>c</SUB>) and a-axis lattice parameter, but significantly improved the critical current density (J<SUB>c</SUB>) in high fields, upper critical field (H<SUB>c2</SUB>), and irreversibility field (H<SUB>irr</SUB>) performances. These results are attributed to the replacement of B sites with C by the PAN doping. Furthermore, as expected, the MgO amount did not increase as the doping content increased. The J<SUB>c</SUB> of the PAN-doped MgB<SUB>2</SUB> wires was more than one order of magnitude higher than that of the undoped MgB<SUB>2</SUB> wire at 5K and 6.6T (1.46-3.82kA/cm<SUP>2</SUP> vs. 0.11kA/cm<SUP>2</SUP>).

Investigation of lauric acid dopant as a novel carbon source in MgB₂ wire

Lee, C.M.,Lee, S.M.,Park, G.C.,Joo, J.,Lim, J.H.,Kang, W.N.,Yi, J.H.,Jun, B.H.,Kim, C.J. North-Holland 2010 Physica. C, Superconductivity Vol.470 No.20

We fabricated lauric acid (LA) doped MgB<SUB>2</SUB> wires and investigated the effects of the LA doping. For the fabrication of the LA-doped MgB<SUB>2</SUB> wires, B powder was mixed with LA at 0-5wt.% of the total amount of MgB<SUB>2</SUB> using an organic solvent, dried, and then the LA-treated B and Mg powders were mixed stoichiometrically. The powder mixture was loaded into an Fe tube and the assemblage was drawn and sintered at 900<SUP>o</SUP>C for 3h under an argon atmosphere. We observed that the LA doping induced the substitution of C for the B sites in MgB<SUB>2</SUB> and that the actual content of C increased monotonically with increasing LA doping level. The LA-doped MgB<SUB>2</SUB> wires exhibited a lower critical temperature (T<SUB>c</SUB>), but better critical current density (J<SUB>c</SUB>) behavior in a high magnetic field: the 5wt.% LA-doped sample had a J<SUB>c</SUB> value of 5.32x10<SUP>3</SUP>A/cm<SUP>2</SUP>, which was 2.17 times higher than that of the pristine sample (2.45x10<SUP>3</SUP>A/cm<SUP>2</SUP>) at 5K and 6T, suggesting that LA is an effective C dopant in MgB<SUB>2</SUB> for enhancing the high-field J<SUB>c</SUB> performance.