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Oh, Ji Seop,Kim, Minu,Kim, Gideok,Lee, Han Gyeol,Yoo, Hyang Keun,Sinn, Soobin,Chang, Young Jun,Han, Moonsup,Jozwiak, Chris,Bostwick, Aaron,Rotenberg, Eli,Kim, Hyeong-Do,Noh, Tae Won Elsevier 2018 Current Applied Physics Vol.18 No.6
<P><B>Abstract</B></P> <P>We investigated the atomic configuration and the electronic structure of a BaBiO<SUB>3</SUB> (BBO) thin film and its (001) surface. It was theoretically predicted that two-dimensional electron gases would be formed when the film is BiO<SUB>2</SUB>-terminated. We deduced depth-profile information for a BBO thin film using angle-dependent X-ray photoemission spectroscopy. Analysis of the spectral weights of the Ba 3d and Bi 4<I>f</I> core levels confirmed that the BBO film should have a BiO<SUB>2</SUB>-terminated topmost layer. We used <I>in-situ</I> angle-resolved photoemission spectroscopy to experimentally determine the electronic structure of a BBO thin film and found no metallic surface state. We distinguished surface states from bulk states by evaporating potassium atoms <I>in-situ</I> on the surface. A surface state near the bottom of the topmost bulk valence band, which was predicted by the DFT calculations, was identified. However, other surface states well separated from the bulk states were not observed. Our results provided evidence that descriptions of the BBO electronic structure require more detailed and elaborate approaches.</P> <P><B>Highlights</B></P> <P> <UL> <LI> An atomic configuration and a surface state of a BiO<SUB>2</SUB>-terminated BaBiO<SUB>3</SUB> thin film were studied. </LI> <LI> The depth-profile information of our BaBiO<SUB>3</SUB> film was investigated and it had a BiO<SUB>2</SUB> termination layer. </LI> <LI> Contrary to the theoretical proposal for a 2DEG on a BiO<SUB>2</SUB>-terminated BaBiO<SUB>3</SUB>, no surface metallic state was observed. </LI> <LI> The absence of the metallic surface state may be attributed to misprediction on the band gap size. </LI> </UL> </P>
Software certification of safety-critical avionic systems: DO-178C and its impacts
Won Keun Youn,Seung Bum Hong,Kyung Ryoon Oh,Oh Sung Ahn IEEE 2015 IEEE aerospace and electronic systems magazine Vol.30 No.4
<P>This article presents an overview of the new guidelines for safety-critical airborne software contained in DO-178C and supplementary documents. The similarity between DO178B and DO-178C is presented by reviewing the basics of DO178 verification philosophy, and an overview of the major new guidance in DO-178C is presented to highlight what has been changed, along with a description of the impact of DO-178C on the industry. The remaining sections of the article provide a discussion of the new guidelines in the supplementary documents: DO-330 to DO-333.</P>
Oh, Seok-Kyun,Kim, Gwang-Won,Yang, Jong-Chul,Kim, Seok-Kwun,Kang, Heoung-Keun,Jeong, Gwang-Woo The Korean Society of Radiology 2012 KOREAN JOURNAL OF RADIOLOGY Vol.13 No.3
<P><B>Objective</B></P><P>This study used functional magnetic resonance imaging (fMRI) to contrast the differential brain activation patterns in response to visual stimulation with both male and female erotic nude pictures in male-to-female (MTF) transsexuals who underwent a sex reassignment surgery.</P><P><B>Materials and Methods</B></P><P>A total of nine healthy MTF transsexuals after a sex reassignment surgery underwent fMRI on a 3.0 Tesla MR Scanner. The brain activation patterns were induced by visual stimulation with both male and female erotic nude pictures.</P><P><B>Results</B></P><P>The sex hormone levels of the postoperative MTF transsexuals were in the normal range of healthy heterosexual females. The brain areas, which were activated by viewing male nude pictures when compared with viewing female nude pictures, included predominantly the cerebellum, hippocampus, putamen, anterior cingulate gyrus, head of caudate nucleus, amygdala, midbrain, thalamus, insula, and body of caudate nucleus. On the other hand, brain activation induced by viewing female nude pictures was predominantly observed in the hypothalamus and the septal area.</P><P><B>Conclusion</B></P><P>Our findings suggest that distinct brain activation patterns associated with visual sexual arousal in postoperative MTF transsexuals reflect their sexual orientation to males.</P>
A Genetic Risk Score for Atrial Fibrillation Predicts the Response to Catheter Ablation
Won-Seok Choe,Jun Hyuk Kang,Eue-Keun Choi,Seung Yong Shin,Steven A. Lubitz,Patrick T. Ellinor,Seil Oh,Hong Euy Lim 대한심장학회 2019 Korean Circulation Journal Vol.49 No.4
Background and Objectives: The association of susceptibility loci for atrial fibrillation (AF) with AF recurrence after ablation has been reported, although with controversial results. In this prospective cohort analysis, we aimed to investigate whether a genetic risk score (GRS) can predict the rhythm outcomes after catheter ablation of AF. Methods: We determined the association between 20 AF-susceptible single nucleotide polymorphisms (SNPs) and AF recurrence after catheter ablation in 746 patients (74% males; age, 59±11 years; 56% paroxysmal AF). A GRS was calculated by summing the unweighted numbers of risk alleles of selected SNPs. A Cox proportional hazard model was used to identify the association between the GRS and risk of AF recurrence after catheter ablation. Results: AF recurrences after catheter ablation occurred in 168 (22.5%) subjects with a median follow-up of 23 months. The GRS was calculated using 5 SNPs (rs1448818, rs2200733, rs6843082, rs6838973 at chromosome 4q25 [PITX2] and rs2106261 at chromosome 16q22 [ZFHX3]), which showed modest associations with AF recurrence. The GRS was significantly associated with AF recurrence (hazard ratio [HR] per each score, 1.13; 95% confidence interval [CI], 1.03–1.24). Patients with intermediate (GRS 4–6) and high risks (GRS 7–10) showed HRs of 2.00 (95% CI, 0.99–4.04) and 2.66 (95% CI, 1.32–5.37), respectively, compared to patients with low risk (GRS 0–3). Conclusions: Our novel GRS using 5 AF-susceptible SNPs was strongly associated with AF recurrence after catheter ablation in Korean population, beyond clinical risk factors. Further efforts are warranted to construct a generalizable, robust genetic prediction model which can guide the optimal treatment strategies.
Herbicidal Activity and Mode of Action of Streptomyces scopuliridis Metabolites
Won, Ok Jae,Kim, Young Tae,Choi, Jung Sup,Oh, Taek-Keun,Shinogi, Yoshiyuki,Park, Kee Woong FACULTY OF AGRIC PUBLICATIONS-KYUSHU UNIV 2016 Journal of the Faculty of Agriculture, Kyushu Univ Vol. No.
<P>This study was conducted to examine the effects and the mode of action of a natural herbicidal substance, Streptomyces scopuliridis metabolites (SSM), which consists of herbicidin A and herbicidin B, derived from Streptomyces scopuliridis. Necrosis of Echinochloa oryzoides, Digitaria ciliaris, Abutilon theophrasti and Amaranthus retroflexus occurred within 3 days of SSM application at the concentration of 4,000 ppm. Symptoms of herbicidal action of SSM started to show soon following application, and appeared earlier than those caused by glyphosate but later than those caused by paraquat. Overall, herbicidal action of SSM appeared with a time interval similar to glufosinate ammonium following foliar application. Chlorophyll fluorescence level (Fv/Fm) was not affected by SSM application suggesting that SSM application did not inhibit photosynthesis of the treated plants. The amount of electrolyte leakage caused by SSM increased steadily with time, and was proportional to the concentration of SSM. Electrolyte leakage induced by paraquat occurred more rapidly than by SSM. No signs of translocation of SSM in a downward direction through the phloem was observed in either D. ciliaris or A. theophrasti. Based on the results from this study, the mode of action of SSM involves the rapid disruption of cell membrane caused by an unknown mechanism other than inhibition of photosynthesis. In the future, SSM would be a good candidate for a contact herbicide; however, a better understanding of its mode of action has to precede attempts for commercial development and practical application.</P>
Oh, Chan-Ho,Kim, Nam-Seok,Yang, Jae-Heon,Lee, Hyun-Jin,Yang, Seok-Won,Park, Sae-Rom,So, Un-Ki,Bae, Jin-Beom,Eun, Jae-Soon,Jeon, Hoon,Lim, Jong-Pil,Kwon, Jin,Kim, Young-Suk,Shin, Tae-Yong,Kim, Dae-Keun 대한약학회 2010 Archives of Pharmacal Research Vol.33 No.4
Three compounds were isolated from the ethyl acetate soluble fraction of the methanolic extract of the leaves of Catalpa ovata (Bignoniaceae) through repeated column chromatography. We investigated the effects of these compounds on T cell-mediated responses for tumor surveillance and proliferation in U937, HL60, and Molt-4 leukemia cells. Compounds 1-3 inhibited proliferation of those cells in a dose-dependent manner. Compound 3 showed mild effect in Molt-4 cell cytotoxicity. Compound 3 enhanced gene expressions of p53 and IL-4, but decreased IL-2 and IFN-${\gamma}$ genes in Molt-4 cell. Our findings indicate that compound 3 may enhance T cell-mediated immune responses and anticancer properties.
A numerical simulation for reduction of rudder cavitation with gap flow blocking bars
Oh, Jung-Keun,Lee, Seung-Hee,Kim, Sang-Hyun,Seo, Dae-Won The Society of Naval Architects of Korea 2012 International Journal of Naval Architecture and Oc Vol.4 No.2
In recent practices, a half circular prismatic bar protruding beyond the concave surface of the horn facing the gap has been formed along the centerplane of a rudder to lessen the gap flow between the horn and the movable portion of the rudder system. If a flow through the gap of a rudder is reduced considerably through this approach, previous numerical studies indicate that not only the gap flow but also the rudder cavitation can be noticeably diminished. In the present study, numerical simulations on two-dimensional rudder sections were performed to show that the blocking ability of the single centre bar can be improved by the proper choice of sectional shape. Moreover, a pair of blocking bars attached symmetric to the centerplane on the opposite convex surface of the movable portion is suggested in the study as well, to circumvent the difficulties arising from the practical application of the single centre bars. The bars are placed near the outer edges of the gap easily accessible at the maximum rudder angle to allow simple installation of the device during a maintenance period of a ship. It is found that the pair of blocking bars further improves the blocking effects and application to a practical three-dimensional rudder also backs up the fact.
Inhibitory Activity of Isorhamnetin from Persicaria thunbergii on Farnesyl Protein Transferase
Oh Hyun Mi,Kwon Byoung-Mog,Baek Nam-In,Kim Sung-Hoon,Chung In-Sik,Park Mi-Hyun,Park Hee Wook,Lee Jae Hyeok,Park Hye Won,Kim Eun Jeong,Kim Dae Keun The Pharmaceutical Society of Korea 2005 Archives of Pharmacal Research Vol.28 No.2
The methanolic extract of the aerial parts of Persicaria thunbergii was found to show inhibitory activity on Farnesyl Protein Transferase (FPTase). Bioassay-guided fractionation of the methanolic extract resulted in the isolation of isorhamnetin, as an inhibitor on FPTase. This compound inhibited FPTase activity in a dose-dependent manner, and the $IC_{50}$ value of isorhamnetin was $37.5\;{\mu}M$.