Quasi-Monoenergetic Electron-Beam Generation Using a Laser Accelerator for Ultra-Short X-ray Sources

J Kim,고도경,석희용,H Jang,김형택,I Hwang,최일우,J Lim,J. Lee,J. H. Sung,K.-H. Hong,허민섭,N Hafz,유승훈,유태준,T. M. Jeong,V Kulagin,Y.-C. Noh 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.51 No.I

Two types of electron acceleration methods have been conducted to generate quasi-monoenergetic electron beams. Multi-MeV quasi-monoenergetic high-charge electron beams were generated at Korea Electrotechnology Research Institute (KERI) from self-modulated laser wakefield acceleration by using a collimator with a 2 TW (1.4 J/700 fs) Nd:glass/Ti:sapphire hybrid laser system and a supersonic nitrogen gas jet. The peak electron energy was 3.6 MeV, and the energy spread was 4 MeV. These electron beams are useful for the generation of short-pulse X-rays in the water window region, which is 250 eV -- 500 eV (2.5 -- 5 nm), by using Thomson scattering. The calcualted photon spectrum indicates the scattered photon covers the water window region. This can be used for a high spatial and temperal resolution microscope for medical imaing. To generate higher-energy electron beams with small energy spread, a laser wakefield acceleration experiment with a sharp downward electron density gradient was conducted with a 100 TW laser system at Advanced Photon Research Insistitute (APRI). With the electron density gradient, some background plasma electrons could be locally injected in the laser wake wave and a small energy spread was expected. Using the pre-pulse, we could generate sharp downward electron density gradients. The gradient scale length was 20 $\mu$m for a 25 \% density change. With this electron density gradient, we could get more reproducible electron beams than we could without the density gradient.

Progression of primary open angle glaucoma in asymmetrically myopic eyes

Song, M. K.,Sung, K. R.,Han, S.,Lee, J. E.,Yoon, J. Y.,Park, J. M.,Lee, J. Y. Springer Science + Business Media 2016 Graefe's archive for clinical and experimental oph Vol.254 No.7

<P>To compare progression of primary open angle glaucoma (POAG) in asymmetrically myopic eyes within the same subject and evaluate whether the degree of myopia is related to glaucoma progression. POAG patients with asymmetric myopia (axial length [AXL] a parts per thousand yen24 mm in both eyes, and the AXL difference between the right and left eyes to be a parts per thousand yen0.5 mm) were included. Glaucoma progression was determined either by optic disc/retinal nerve fiber layer (RNFL) photographs or by serial visual field (VF) data. The progression rates of VF mean deviation (dB/year) and spectral domain optical coherence tomography measured RNFL thickness (mu m/year) were compared between the more myopic eye (MME) and the less myopic eye (LME) within the same subject. A total of 55 patients (mean follow up period; 4.5 +/- 1.0 years) were included. The mean AXL demonstrated a significant difference between MME and LME (26.3 +/- 1.7 vs. 25.6 +/- 1.7 mm; p = 0.036). The mean baseline VF MD (-3.8 +/- 5.4 vs. -2.6 +/- 4.7 dB; p = 0.21) and average RNFL thickness (77.5 +/- 10.6 vs. 79.9 +/- 12.3 mu m; p = 0.36) did not differ between the MME and LME. Among the 55 patients, optic disc/RNFL photographic progression was noted in the MME in 15 patients, in the LME in 19 patients, and in both eyes in seven patients. VF progression was noted in the MME in seven patients, in the LME in seven patients, and in both eyes in four patients. The VF MD progression rates were -0.25 +/- 0.34 dB/year in MME and -0.26 +/- 0.34 dB/year in LME cases (p = 0.91). The mean progression rate of the average RNFL thickness also did not differ between the MME and LME (-0.59 +/- 0.67 vs. -0.66 +/- 0.72 mu m/year, p = 0.68). The degree of myopia was not associated with glaucoma progression when assessing the same patient using either the VF or optic disc/RNFL criteria in asymmetrically myopic patients.</P>

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>).

Study on the improved J_c(B) performance of polyacrylic acid-doped MgB₂ bulks

Hwang, S.M.,Lee, C.M.,Lee, S.M.,Sung, K.,Joo, J.,Lim, J.H.,Kang, W.N.,Kim, C.J. North-Holland 2010 Physica. C, Superconductivity Vol.470 No.suppl1

We fabricated polyacrylic acid (PAA)-doped MgB<SUB>2</SUB> bulks by wet mixing and in situ reaction process and studied the relationships between the phase formation, lattice change, microstructure, and critical properties according to the PAA doping level. The PAA doping increased the MgO amount and grain boundary area but decreased the a-axis lattice constant and critical temperature (T<SUB>c</SUB>), which is indicative of the substitution of B sites by C in MgB<SUB>2</SUB>. Furthermore, the critical current density (J<SUB>c</SUB>) at high magnetic fields improved with the increasing PAA content to 5.99kA/cm<SUP>2</SUP> for the 7wt% PAA-doped sample, which was about 6-fold higher than that of the pure sample at 5K and 6.6T. This improvement was mainly attributed to the C substitution and the fine grain size due to PAA doping, suggesting that PAA is an effective dopant in improving J<SUB>c</SUB>(B) performance of MgB<SUB>2</SUB>.

New teleomorph combinations in the entomopathogenic genus <i>Metacordyceps</i>

Kepler, R.M.,Sung, G.-H.,Ban, S.,Nakagiri, A.,Chen, M.-J.,Huang, B.,Li, Z.,Spatafora, J.W. Informa UK (TaylorFrancis) 2012 Mycologia Vol.104 No.1

<P>The genus Metacordyceps contains arthropod pathogens in Clavicipitaceae (Hypocreales) that formerly were classified in Cordyceps sensu Kobayasi et Mains. Of the current arthropod pathogenic genera of Hypocreales, the genus Metacordyceps remains one of the most poorly understood and contains a number of teleomorphic morphologies convergent with species of Cordyceps s.s. (Cordycipitaceae) and Ophiocordyceps (Ophiocordycipitaceae). Of note, the anamorph genera Metarhizium and Pochonia were found to be associated only with Metacordyceps and demonstrated to be phylogenetically informative for the clade. Several species of Cordyceps considered to have uncertain placements (incertae sedis) in the current taxonomic framework of clavicipitoid fungi were collected during field expeditions mostly in eastern Asia. Species reclassified here in Metacordyceps include Cordyceps atrovirens Kobayasi & Shimizu, Cordyceps indigotica Kobayasi & Shimizu, Cordyceps khaoyaiensis Hywel-Jones, Cordyceps kusanagiensis Kobayasi & Shimizu, Cordyceps martialis Speg., Ophiocordyceps owariensis Kobayasi, Cordyceps pseudoatrovirens Kobayasi & Shimizu and Ophicordyceps owariensis f. viridescens (Uchiy. & Udagawa) G.H. Sung, J.M. Sung, Hywel-Jones & Spatafora. Incorporation of these species in a multigene phylogenetic framework of the major clades of clavicipitoid fungi more than doubled the number of species in Metacordyceps and allowed for refinement of morphological concepts for the genus consistent with the phylogenetic structure. Based on these findings we then discuss evolution of this genus, subgeneric relationships, anamorph connections, and suggest additional species that should be confirmed for possible inclusion in Metacordyceps.</P>

Planck Cold Clumps in the <i>λ</i> Orionis Complex. II. Environmental Effects on Core Formation

Yi, Hee-Weon,Lee, Jeong-Eun,Liu, Tie,Kim, Kee-Tae,Choi, Minho,Eden, David,II, Neal J. Evans,Francesco, James Di,Fuller, Gary,Hirano, N.,Juvela, Mika,Kang, Sung-ju,Kim, Gwanjeong,M. Koch, Patrick,Lee, American Astronomical Society 2018 The Astrophysical journal, Supplement series Vol.236 No.2

<P>Based on the 850 mu m dust continuum data from SCUBA-2 at James Clerk Maxwell Telescope (JCMT), we compare overall properties of Planck Galactic Cold Clumps (PGCCs) in the lambda Orionis cloud to those of PGCCs in the Orion A and B clouds. The Orion A and B clouds are well-known active star-forming regions, while the A Orionis cloud has a different environment as a consequence of the interaction with a prominent OB association and a giant H-II region. PGCCs in the lambda Orionis cloud have higher dust temperatures (T-d = 16.13 +/- 0.15 K) and lower values of dust emissivity spectral index (beta = 1.65 +/- 0.02) than PGCCs in the Orion A (T-d = 13.79 +/- 0.21 K, beta = 2.07 +/- 0.03) and Orion B (T-d = 13.82 +/- 0.19 K, beta =1.96 +/- 0.02) clouds. We find 119 substructures within the 40 detected PGCCs and identify them as cores. Out of a total of 119 cores, 15 cores are discovered in the lambda Orionis cloud, while 74 and 30 cores are found in the Orion A and B clouds, respectively. The cores in the lambda Orionis cloud show much lower mean values of size R = 0.08 pc, column density N(H-2) (9.5 +/- 1.2) x 10(22)cm(-2) , number density n(H-2) - (2.9 +/- 0.4) x 10 5 CM -3 , and mass M-core = 1.0 +/- 0.3 M(circle dot)compared to the cores in the Orion A [R = 0.11 pc, N(H-2) = (2.3 +/- 0.3) x 10(23) cm(-2), n(H-2) = (3.8 +/- 0.5) x 10(5)cm(-3) , and M-core = 2.4 +/- 0.3 M-circle dot] and Orion B [R = 0.16 pc, N(H-2) (3.8 +/- 0.4) x 10(23) cm(-2), n(H-2) = (15.6 +/- 1.8) x 10(5) cm(-3) , and M-core = 2.7 +/- 0.3 M-circle dot] clouds. These core properties in the A Orionis cloud can be attributed to the photodissociation and external heating by the nearby H rr region, which may prevent the PGCCs from forming gravitationally bound structures and eventually disperse them. These results support the idea of negative stellar feedback on core formation.</P>

한국잔디 수집계통들 중에서 우수계통들의 생육특성 비교

임용우(Y. W. Rim),김기용(K. Y. Kim),김맹중(M. J. Kim),성병렬(B. R. Sung),임영철(Y. C. Lim),정의수(E. S. Chung),신홍균(H. K. Shin),김용선(Y. S. Kim) 한국잡초학회·한국잔디학회 2003 Weed & Turfgrass Science Vol.17 No.2,3

2001년 수집된 한국잔디 133계통들 중에서 우수한 계통들을 선발하기위하여 밀도(품질),<br/> 피복성, 녹색기간, 내병성, 출수유무(종자수) 등의 주요특성과 그 외 생육특성들이 조사되었다. 생육특성이 우수한 6계통이 선발되었으며 그 결과를 요약하면 다음과 같다.<br/> 수집된 133계통들 중에서 가장 녹색기간이긴 계통은 J01067으로 11월초까지 녹색도를 유지하였다. J01106 및 J01129 계통들은 엽폭이 각각 1.5mm 및 2mm 정도로 매우 좁으며, 밀도가 높고, 피복성도 좋은 것으로 나타났으며, 내병성도 강하였다. J01122 계통은 들잔디 계통들 중에서 유일하게 내병성이 강한 계통으로 선발되었다. J01128 계통은 엽폭이 3.2mm로 중엽에 속하였으며, 대비품종인 Sunburst 와 비슷하였다. 이 계통의 경우도J01106, J01129 계통들과 마찬가지로 밀도가 높고 내병성이 강한 것으로 나타났다.<br/> 수집된 133계통들의 형태적 분류를 위하여 5가지의 생육특성을 사용하여 크게 세가지 군집<br/> 으로 분류하였으며, 그 중에서 대비품종으로 사용된 6품종들과 선발된 우수 6계통의 분류는<br/> 다음과 같다. 제 1군집에 속하는 품종 및 계통은 Belare, Meyer, 안양중지(Anyang-jungji), J01067, J01112 등이 포함되었으며, 제 2군집으로는 S-94, J01105가 포함되었고, 제 3군집에는 Sunburst, 건희(Konhee), J01106, J01128, J01129 등이 포함되었다. Growth characteristics such as density(quality), covering speed, green period, disease resistance, heading existence(number of seeds) and other characteristics were examined for selection of superior lines among the 133 zoysiagrass lines collected in 2001. Six superior lines were selected and the results were summarized as follows.<br/> Superior line, J01067 was longest for green period among the 133 zoysiagrasses and stayed green until the beginning of November. Leaf width of J01106 and J01129 lines was very narrow as 1.5㎜ and 2㎜, respectively and superior for density(quality), covering speed and disease resistance. J01122 line was selected for strongest disease resistance among the lines of Zoysia japonica. Leaf width of J01128 was 3.2㎜ showing midium type and similar to standard cultivar, Sunburst. This line also showed higher density and strong disease resistance like J01106 and J01129.<br/> Five growth characteristics for morphological classification of 133 zoysiagrass lines<br/> was used and divided into 3 cluster groups. Of 133 lines, 6 standard cultivars and 6 superior lines were classified as follows. First cluster group contained Belare, Meyer, Anyang-jungji, J01067, J01122, and second group contained S-94 and J01105, and third group contained Sunburst, Konhee, J01106, J01128 and J01129.<br/> <br/>

Triarylborane Lewis acids with indole or phenol group: B/H hybrid receptors for fluoride

Sung, W.Y.,Lee, J.,Lee, M.H. Elsevier Sequoia 2015 Journal of organometallic chemistry Vol.776 No.-

Triarylboranes bearing an indole ((indol-7-yl)Mes<SUB>2</SUB>B, 1) or phenol ((phenol-2-yl)Mes<SUB>2</SUB>B, 2) group were prepared and characterized as a novel class of boron/hydrogen bond (B/H) hybrid receptors for fluoride. X-ray crystal structures revealed the presence of proximal X-H bond (X = N, O) to the trigonal boron center. UV/Vis absorption titrations of 1 and 2 with fluorides resulted in the corresponding fluoride adduct with high binding constants (4.0 x 10<SUP>7</SUP> M<SUP>-1</SUP> in DMSO for 1 and 3.0 x 10<SUP>7</SUP> M<SUP>-1</SUP> in THF for 2). Comparative fluoride binding experiments with the triarylboranes lacking an X-H bond showed the enhanced fluoride binding affinity of 1 and 2 with an increase of one order of magnitude. <SUP>1</SUP>H NMR spectroscopic titrations confirmed that the dative B-F interaction was assisted by X-H...F hydrogen bonding.

Study of historical Chinese lacquer culture and technology - Analysis of Chinese Qin-Han dynasty lacquerware

Sung, M.,Jung, J.,Lu, R.,Miyakoshi, T. Elsevier 2016 Journal of cultural heritage Vol.21 No.-

<P>A Chinese Qin-Han dynasty lacquerware was analyzed by cross-section, field emission scanning electron microscope with energy dispersive X-ray spectrometry (EDX), strontium isotope ratios (Sr-87/Sr-86), carbon-14 age determination, and pyrolysis-gas chromatography-mass spectrometry. The carbon-14 analysis results showed that the wood base was from a Zelkova schneideriana tree grown in the Yangtze River area about 2300 years ago, and the film was sap collected from lacquer tree about 2200-2250 years ago. The Sr-87/Sr-86 isotope ratio was 0.71146 consistent with that of the Chinese mainland ( >0.71). Pyrolysis GC-MS detected 3-heptylphenol and 3-pentadecylphenol in the mass chromatograms at m/z=108, and palmitic acid and stearic acid were detected at m/z=60, suggesting that the sap collected from Toxicodendron vernicifluum tree and that many additives had been added. The cross-section and EDX revealed the coating technique and pigment species of lacquerware. Based on these results, the Chinese Qin-Han Dynasty lacquer culture is discussed. (C) 2016 Elsevier Masson SAS. All rights reserved.</P>

Neocalimastix frontalis 로 조제한 fungal additive 가 반추위 발효에 미치는 영향

하종규,강민원,이상석 한국동물자원과학회 2000 한국축산학회지 Vol.42 No.5

The anaerobic rumen fungus, N. frontalis N1-1, which had a high fiber-degrading capacity was selected to make a fungal additive and to evaluate its effects on ruminal fermentation. The fungal additive was added at the level of 0.03, 0.06, 0.09, and 0.12%(w/v) in Lowe's medium and pH, gas production, dry matter degradation, CMCase, xylanase, and volatile fatty acid(VFA) were determined after 2, 4, and 6 days of incubation. Addition of high level of fungal additive (0.09 and 0.12%) decreased pH compared with control treatment(P$lt;0.05). The gas production was increased by the addition of fungal additive. The highest increase in gas production was achieved with 0.09, and 0.1% supplementation after 6 days incubation(P$lt;0.05). The degradation of dry matter was increased with incubation time up to 6 days and was significantly lower in control. Activities of carboxymethylcellulase(CMCase), and xylanase in the culture supernatant was increased by the addition of fungal additive with highest increase after 4 days of incubation. Total VFA production and acetate:propionate ratio also tended to increase by fungal additive after 4 days of incubation similar to results of enzyme activities.