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Search Results: 1 - 10 of 33354 matches for " Young-Soo Jo "
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Is Dust Cloud around $λ$ Orionis a Ring or a Shell, or Both?
Dukhang Lee,Kwang-Il Seon,Young-Soo Jo
Physics , 2015,
Abstract: The dust cloud around $\lambda$ Orionis is observed to be circularly symmetric with a large angular extent ($\approx$ 8 degrees). However, whether the three-dimensional (3D) structure of the cloud is shell- or ring-like has not yet been fully resolved. We study the 3D structure using a new approach that combines a 3D Monte Carlo radiative transfer model for ultraviolet (UV) scattered light and an inverse Abel transform, which gives a detailed 3D radial density profile from a two-dimensional column density map of a spherically symmetric cloud. By comparing the radiative transfer models for a spherical shell cloud and that for a ring cloud, we find that only the shell model can reproduce the radial profile of the scattered UV light, observed using the S2/68 UV observation, suggesting a dust shell structure. However, the inverse Abel transform applied to the column density data from the Pan-STARRS1 dust reddening map results in negative values at a certain radius range of the density profile, indicating the existence of additional, non-spherical clouds near the nebular boundary. The additional cloud component is assumed to be of toroidal ring shape; we subtracted from the column density to obtain a positive, radial density profile using the inverse Abel transform. The resulting density structure, composed of a toroidal ring and a spherical shell, is also found to give a good fit to the UV scattered light profile. We therefore conclude that the cloud around $\lambda$ Ori is composed of both ring and shell structures.
Far-ultraviolet study of the local supershell GSH 006-15+7
Young-Soo Jo,Kyoung-Wook Min,Kwang-Il Seon
Physics , 2015,
Abstract: We have analyzed the archival data of FUV observations for the region of GSH 006-15+7, a large shell-like structure discovered by Moss et al. (2012) from the H I velocity maps. FUV emission is seen to be enhanced in the lower supershell region. The FUV emission is considered to come mainly from the scattering of interstellar photons by dust grains. A corresponding Monte Carlo simulation indicates that the distance to the supershell is 1300 +- 800 pc, which is similar to the previous estimation of 1500 +- 500 pc based on kinematic considerations. The spectrum at lower Galactic latitudes of the supershell exhibits molecular hydrogen fluorescence lines; a simulation model for this candidate photodissociation region (PDR) yields an H_2 column density of N(H_2) = 10^{18.0-20.0} cm^{-2} with a rather high total hydrogen density of n_H ~ 30 cm^{-3}.
Simulation Study of Dust-Scattered Far-Ultraviolet Emission in the Orion-Eridanus Superbubble
Young-Soo Jo,Kyoung-Wook Min,Tae-Ho Lim,Kwang-Il Seon
Physics , 2012, DOI: 10.1088/0004-637X/756/1/38
Abstract: We present the results of dust scattering simulations carried out for the Orion Eridanus Superbubble region by comparing them with observations made in the far-ultraviolet. The albedo and the phase function asymmetry factor (g-factor) of interstellar grains were estimated, as were the distance and thickness of the dust layers. The results are as follows: 0.43$^{+0.02}_{-0.04}$ for the albedo and 0.45$^{+0.2}_{-0.2}$ for the g-factor, in good agreement with previous determinations and theoretical predictions. The distance of the assumed single dust layer, modeled for the Orion Molecular Cloud Complex, was estimated to be ~110 pc and the thickness ranged from ~130 at the core to ~50 pc at the boundary for the region of the present interest, implying that the dust cloud is located in front of the superbubble. The simulation result also indicates that a thin (~10 pc) dust shell surrounds the inner X-ray cavities of hot gas at a distance of ~70-90 pc.
A Novel Antibacterial Compound from Siegesbeckia glabrescens
Young-Soo Kim,Hyungil Kim,Eunsun Jung,Jang-Hyun Kim,Wangtaek Hwang,Eun-Ju Kang,Sanghyun Lee,Byung-Jo Ha,Jongsung Lee,Deokhoon Park
Molecules , 2012, DOI: 10.3390/molecules171112469
Abstract: The crude methanol extract of the dried aerial parts of Siegesbeckia glabrescens (Compositae) showed antibacterial activity against the foodborne pathogen Staphylococcus aureus. Bioactivity-guided separation led to the isolation of 3-(dodecanoyloxy)-2-(isobutyryloxy)-4-methylpentanoic acid from nature for the first time. The structure was determined by spectroscopic data analysis (UV, MS, and NMR). The minimal inhibitory concentration (MIC) of 3-(dodecanoyloxy)-2-(isobutyryloxy)-4-methylpentanoic acid against S. aureus was found to be 3.12 μg/mL. In addition, in a further antimicrobial activity assay against Gram-positive (B. subtilis, E. faecalis, P. acnes, S. epidermidis, S. schleiferi subsp. coagulans, S. agalactiae and S. pyrogens), and Gram-negative bacteria (E. coli and P. aeruginosa), and yeast strains (C. alibicans and F. neoformans), the antimicrobial activity of the compound was found to be specific for Gram-positive bacteria. The MIC values of the compound for Gram-positive bacteria ranged from 3.12 to 25 mg/mL. Furthermore, it was found that the 2-(isobutyryloxy)-4-methylpentanoic acid substituent may operate as a key factor in the antibacterial activity of the compound, together with the laurate group.
Bright stars observed by FIMS/SPEAR
Young-Soo Jo,Kwang-Il Seon,Kyoung-Wook Min,Yeon-Ju Choi,Tae-Ho Lim,Yeo-Myeong Lim,Jerry Edelstein,Wonyong Han
Physics , 2015,
Abstract: In this paper, we present a catalogue of the spectra of bright stars observed during the sky survey using the Far-Ultraviolet Imaging Spectrograph (FIMS), which was designed primarily to observe diffuse emissions. By carefully eliminating the contamination from the diffuse background, we obtain the spectra of 70 bright stars observed for the first time with a spectral resolution of 2--3 {\AA} over the wavelength of 1370--1710 {\AA}. The far-ultraviolet spectra of an additional 139 stars are also extracted with a better spectral resolution and/or higher reliability than those of the previous observations. The stellar spectral type of the stars presented in the catalogue spans from O9 to A3. The method of spectral extraction of the bright stars is validated by comparing the spectra of 323 stars with those of the International Ultraviolet Explorer (IUE) observations.
Far-Ultraviolet Observations of the Spica Nebula and the Interaction Zone
Yeon-Ju Choi,Kyoung-Wook Min,Kwang-Il Seon,Tae-Ho Lim,Young-Soo Jo,Jae-Woo Park
Physics , 2013, DOI: 10.1088/0004-637X/774/1/34
Abstract: We report the analysis results of far ultraviolet (FUV) observations, made for a broad region around $\alpha$ Vir (Spica) including the interaction zone of Loop I and the Local Bubble. The whole region was optically thin and a general correlation was seen between the FUV continuum intensity and the dust extinction, except in the neighborhood of the bright central star, indicating the dust scattering nature of the FUV continuum. We performed Monte-Carlo radiative transfer simulations to obtain the optical parameters related to the dust scattering as well as the geometrical structure of the region. The albedo and asymmetry factor were found to be 0.38$\pm$0.06 and 0.46$\pm$0.06, respectively, in good agreement with the Milky Way dust grain models. The distance to and the thickness of the interaction zone were estimated to be 70$^{+4}_{-8}$ pc and 40$^{+8}_{-10}$ pc, respectively. The diffuse FUV continuum in the northern region above Spica was mostly the result of scattering of the starlight from Spica, while that in the southern region was mainly due to the background stars. The \ion{C}{4} $\lambda\lambda$1548, 1551 emission was found throughout the whole region, in contrast to the \ion{Si}{2}* $\lambda$1532 emission which was bright only within the \ion{H}{2} region. This indicates that the \ion{C}{4} line arises mostly at the shell boundaries of the bubbles, with a larger portion likely from the Loop I than from the Local Bubble side, whereas the \ion{Si}{2}* line is from the photoionized Spica nebula.
Abscess in the Splenium of the Corpus Callosum Treated with Direct Drainage via an Occipital Interhemispheric Approach  [PDF]
Yasushi Motoyama, Hisashi Kawai, Yohei Kogeichi, Pritam Gurung, Young-Soo Park, Hiroyuki Nakase
Open Journal of Modern Neurosurgery (OJMN) , 2015, DOI: 10.4236/ojmn.2015.51006
Abstract: Lesions in the corpus callosum typically represent malignant tumors such as glioblastoma or lymphoma, because of its compact structure comprising tightly packed white-matter tracts. Brain abscess is rarely seen in the corpus callosum. To the best of our knowledge, solitary bacterial abscess confined to the splenium of the corpus callosum has not been reported previously. We report the case of a 72-year-old woman with rapidly progressing disturbance of consciousness following 1 week of antibiotic treatment for bacterial meningitis. Magnetic resonance imaging demonstrated a ring-enhancing round mass located in the splenium of the corpus callosum on gadolinium-enhanced T1-weighted imaging, also showing a bright signal on diffusion-weighted imaging. The patient underwent occipital craniotomy and direct drainage of the lesion in the splenium through the interhemispheric fissure and achieved complete recovery. Brain abscess should be considered among the differential diagnoses for lesions in the splenium of the corpus callosum. An occipital interhemispheric approach to the splenium might be an important option in cases of brain abscess.
Translation and validation of the Korean confusion assessment method for the intensive care unit
Eun Heo, Byoung-Jo Lee, Bong-Jin Hahm, Eun Song, Han-A Lee, Chul-Gyu Yoo, Young Kim, Sung Han, Young-Soo Shim, Sang-Min Lee
BMC Psychiatry , 2011, DOI: 10.1186/1471-244x-11-94
Abstract: Translation of the CAM-ICU was done according to the guidelines suggested by the Translation and Cultural Adaptation Group. For validation and interrater reliability assessment of the Korean CAM-ICU, two nurses independently assessed delirium in ICU patients and the results were compared with the reference evaluation, which was done by a psychiatrist using the Diagnostic and Statistical Manual of Mental Disorders IV (DSM-IV).Twenty-two patients were evaluated by two nurses and one psychiatrist expert independently. During the study period, we have continuously educated study nurses. Based on DSM-IV criteria, 16 out of 22 (72.7%) patients developed delirium. The sensitivities of the two nurses' evaluations using the Korean CAM-ICU were 89.80% for nurse 1 and 77.40% for nurse 2. Their specificities were 72.40% and 75.80% and their overall accuracy was 83.33% and 88.37% respectively. The Korean CAM-ICU was done with reasonable interrater reliability between nurse 1 and nurse 2 (κ = 0.81, p < 0.001).The Korean CAM-ICU showed good validity and could be incorporated into clinical practice in Korean ICUs.ISRCTN: ISRCTN50265663Delirium is defined in the Diagnostic and Statistical Manual of Mental Disorders IV (DSM IV) as a disturbance of consciousness with inattention accompanied by a change in cognition or perceptual disturbance that develops over a short period and fluctuates over time [1]. Delirium is a common problem in patients in the intensive care unit (ICU) because of critical illness, medications, various procedures, and numerous risk factors [2]. Ely et al. reported that delirium occurred in between 81.7% and 87% of patients during their ICU stay [3-5]. Delirium itself is an independent predictor of mortality and longer hospital stay in ICU patients [5-7]. Therefore, the Society of Critical Care Medicine (SCCM) guidelines recommend routine assessment for the presence of delirium in ICU patients [8].Despite the high prevalence and clinical importance of delirium in
Mechanical Properties of Silicon Nanowires
Sohn Young-Soo,Park Jinsung,Yoon Gwonchan,Song Jiseok
Nanoscale Research Letters , 2009,
Abstract: Nanowires have been taken much attention as a nanoscale building block, which can perform the excellent mechanical function as an electromechanical device. Here, we have performed atomic force microscope (AFM)-based nanoindentation experiments of silicon nanowires in order to investigate the mechanical properties of silicon nanowires. It is shown that stiffness of nanowires is well described by Hertz theory and that elastic modulus of silicon nanowires with various diameters from ~100 to ~600 nm is close to that of bulk silicon. This implies that the elastic modulus of silicon nanowires is independent of their diameters if the diameter is larger than 100 nm. This supports that finite size effect (due to surface effect) does not play a role on elastic behavior of silicon nanowires with diameter of >100 nm.
Prevalence of clonorchiasis in patients with gastrointestinal disease: A Korean nationwide multicenter survey
Ho Gak Kim, Jimin Han, Myung-Hwan Kim, Kyu Hyun Cho, Im Hee Shin, Gwang Ha Kim, Jae Seon Kim, Jin Bong Kim, Tae Nyeun Kim, Tae Hyeon Kim, Tae Hyo Kim, Jae Woo Kim, Ji Kon Ryu, Young-Soo Moon, Jong Ho Moon, Sung Jae Park, Chan Guk Park, Sung-Jo Bang, Chan
World Journal of Gastroenterology , 2009,
Abstract: AIM: To investigate prevalence of Clonorchis sinensis in patients with gastrointestinal symptoms, and the relation of the infection to hepatobiliary diseases in 26 hospitals in Korea.METHODS: Consecutive patients who had been admitted to the Division of Gastroenterology with gastrointestinal symptoms were enrolled from March to April 2005. Of those who had been diagnosed with clonorchiasis, epidemiology and correlation between infection and hepatobiliary diseases were surveyed by questionnaire.RESULTS: Of 3080 patients with gastrointestinal diseases, 396 (12.9%) had clonorchiasis and 1140 patients (37.2%) had a history of eating raw freshwater fish. Of those with a history of raw freshwater fish ingestion, 238 (20.9%) patients had clonorchiasis. Cholangiocarcinoma was more prevalent in C. sinensis-infected patients than non-infected patients [34/396 (8.6%) vs 145/2684 (5.4%), P = 0.015]. Cholangiocarcinoma and clonorchiasis showed statistically significant positive cross-relation (P = 0.008). Choledocholithiasis, cholecystolithiasis, cholangitis, hepatocellular carcinoma, and biliary pancreatitis did not correlate with clonorchiasis.CONCLUSION: Infection rate of clonorchiasis was still high in patients with gastrointestinal diseases in Korea, and has not decreased very much during the last two decades. Cholangiocarcinoma was related to clonorchiasis, which suggested an etiological role for the parasite.
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