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Search Results: 1 - 10 of 8375 matches for " Jang-Ho Bae "
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The Eclipsing System EP Andromedae and its Circumbinary Companions
Jae Woo Lee,Tobias Cornelius Hinse,Jang-Ho Park
Physics , 2013, DOI: 10.1088/0004-6256/145/4/100
Abstract: We present new long-term CCD photometry for EP And acquired during the period 2007 to 2012. The light curves display total eclipses at primary minima and season-to-season light variability. Our synthesis for all available light curves indicates that the eclipsing pair is a W-type overcontact binary with parameters of q=2.578, i=83.3 deg, $\Delta T$=27 K, f=28 %, and l3=2~3 %. The asymmetric light curves in 2007 were satisfactorily modeled by a cool spot on either of the eclipsing components from a magnetic dynamo. Including our 95 timing measurements, a total of 414 times of minimum light spanning about 82 yr were used for a period study. A detailed analysis of the eclipse timing diagram revealed that the orbital period of EP And has varied as a combination of an upward-opening parabola and two periodic variations, with cycle lengths of P3=44.6 yr and P4=1.834 yr and semi-amplitudes of K3=0.0100 d and K4=0.0039 d, respectively. The observed period increase at a fractional rate of +1.39x10^{-10} is in excellent agreement with that calculated from the W-D code and can be plausibly explained by some combination of mass transfer from the primary to the secondary star and angular momentum loss due to magnetic braking. The most reasonable explanation for both cycles is a pair of light-travel-time effects driven by the possible existence of a third and fourth component with projected masses of M3=0.25 Msun and M4=0.90 Msun. The more massive companion could be revealed using high-resolution spectroscopic data extending over the course of a few years and could also be a binary itself. It is possible that the circumbinary objects may have played an important role in the formation and evolution of the eclipsing pair, which would cause it to have a short initial orbital period and thus evolve into an overcontact configuration by angular momentum loss.
Study design and rationale of 'Influence of Cilostazol-based triple anti-platelet therapy on ischemic complication after drug-eluting stent implantation (CILON-T)' study: A multicenter randomized trial evaluating the efficacy of Cilostazol on ischemic vascular complications after drug-eluting stent implantation for coronary heart disease
Seung-Pyo Lee, Jung-Won Suh, Kyung Woo Park, Hae-Young Lee, Hyun-Jae Kang, Bon-Kwon Koo, In-Ho Chae, Dong-Ju Choi, Seung-Woon Rha, Jang-Whan Bae, Myeong-Chan Cho, Taek-Geun Kwon, Jang-Ho Bae, Hyo-Soo Kim, CILON-T investigators
Trials , 2010, DOI: 10.1186/1745-6215-11-87
Abstract: CILON-T trial was a prospective, randomized, open-label, multi-center, near-all-comer trial to demonstrate the superiority of triple anti-platelet therapy to dual anti-platelet therapy in reducing 6 months' major adverse cardiovascular/cerebrovascular events, composite of cardiac death, nonfatal myocardial infarction, target lesion revascularization and ischemic stroke. It also tested whether triple anti-platelet therapy is superior to dual anti-platelet therapy in inhibiting platelet reactivity in patients receiving percutaneous coronary intervention with drug-eluting stent. Total 960 patients were randomized to receive either dual anti-platelet therapy or triple anti-platelet therapy for 6 months and also, randomly stratified to either lipophilic statin (atorvastatin) or non-lipophilic statin (rosuvastatin) indefinitely. Secondary endpoints included all components of major adverse cardiovascular/cerebrovascular events, platelet reactivity as assessed by VerifyNow P2Y12 assay, effect of statin on major adverse cardiovascular/cerebrovascular events, bleeding complications, and albumin-to-creatinine ratio to test the nephroprotective effect of cilostazol. Major adverse cardiovascular/cerebrovascular events will also be checked at 1, 2, and 3 years to test the 'legacy' effect of triple anti-platelet therapy that was prescribed for only 6 months after percutaneous coronary intervention.CILON-T trial will give powerful insight into whether triple anti-platelet therapy is superior to dual anti-platelet therapy in reducing ischemic events and platelet reactivity in the real-world unselected patients treated with drug-eluting stent for coronary heart disease. Also, it will verify the laboratory and clinical significance of drug interaction between lipophilic statin and clopidogrel.National Institutes of Health Clinical Trials Registry (ClinicalTrials.gov identifier# NCT00776828).Current guidelines recommend at least 6 months of dual anti-platelet agents, consisting of aspi
The Physical Nature and Orbital Behavior of the Eclipsing System DK Cygni
Jae Woo Lee,Jae-Hyuck Youn,Jang-Ho Park,Marek Wolf
Physics , 2015, DOI: 10.1088/0004-6256/149/6/194
Abstract: New CCD photometry is presented for the hot overcontact binary DK Cyg, together with reasonable explanations for the light and period variations. Historical light and velocity curves from 1962 to 2012 were simultaneously analyzed with the Wilson-Devinney (W-D) synthesis code. The brightness disturbances were satisfactorily modeled by applying a magnetic cool spot on the primary star. Based on 261 times of minimum light including 116 new timings and spanning more than 87 yrs, a period study reveals that the orbital period has varied due to a periodic oscillation superposed on an upward parabola. The period and semi-amplitude of the modulation are about 78.1 yrs and 0.0037 d, respectively. This detail is interpreted as a light-travel-time effect due to a circumbinary companion with a minimum mass of $M_3$=0.065 $M_\odot$, within the theoretical limit of $\sim$0.07 M$_\odot$ for a brown dwarf star. The observed period increase at a fractional rate of $+$2.74 $\times $10$^{-10}$ is in excellent agreement with that calculated from our W-D synthesis. Mass transfer from the secondary to the primary component is mainly responsible for the secular period change. We examined the evolutionary status of the DK Cyg system from the absolute dimensions.
Efficacies of the new Paclitaxel-eluting Coroflex Please? Stent in percutaneous coronary intervention; comparison of efficacy between Coroflex Please? and Taxus? (ECO-PLEASANT) trial: study rationale and design
Jae-Bin Seo, Hui-Kyung Jeon, Kyung-Woo Park, Jong-Seon Park, Jang-Ho Bae, Sang-Wook Kim, Keon-Woong Moon, Jae-Woong Choi, Sang-Gon Lee, Woo-Young Chung, Tae-Jin Youn, Soo-Joong Kim, Doo-Il Kim, Byung-Ok Kim, Min-Su Hyon, Keum-Soo Park, Tae-Joon Cha, Hweung-Kon Hwang, Seung-Ho Hur, Hyo-Soo Kim
Trials , 2009, DOI: 10.1186/1745-6215-10-98
Abstract: In the comparison of Efficacy between COroflex PLEASe? ANd Taxus? stent(ECO-PLEASANT) trial, approximately 900 patients are being prospectively and randomly assigned to the either type of Coroflex Please? stent and Taxus Liberte? stent via web-based randomization. The primary endpoint is clinically driven target vessel revascularization at 9 months. The secondary endpoints include major cardiac adverse events, target vessel failure, stent thrombosis and angiographic efficacy endpoints.The ECO-PLEASANT trial is the study not yet performed to directly compare the efficacy and safety of the Coroflex Please? versus Taxus Liberte? stent. On the basis of this trial, we will be able to find out whether the Coroflex Please? stent is non-inferior to Taxus Liberte? stent or not.ClinicalTrials.gov number, NCT00699543.Previous randomized trials have shown the efficacy of a slow-release polymeric sirolimus-eluting stent (Cypher?, Cordis, Warren, NJ, USA), paclitaxel-eluting stent (Taxus?, Boston Scientific, Natick, MA, USA), and zotarolimus-eluting stent (Endeavor?, Medtronic, Minneapolis, MN, USA) over bare metal stents in reducing neointimal hyperplasia, late luminal loss, and angiographic restenosis leading to decreased target lesion revascularization [1-11] The Paclitaxel-eluting Coroflex Please? stent is a newly developed drug eluting stent using the Coroflex? stent platform combined with the drug paclitaxel contained in a polymer coating[12]In the PECOPS I, which was one-arm observational study, the results of Coroflex Please? stent were within the range of other Paclitaxel-eluting coronary stents [12,13] Compared with binary restenosis rate of 7.9% in Taxus IV trial, Coroflex? Please stent showed 7.8% of restenosis rate[7] The 3.1% of 30 day MACE rate is within the range of other trials with stents eluting Paclitaxel or Sirolimus. The 6 month MACE rates in PECOPS I were 8.0%, which was similar to 7.8%, and 8.5% in Taxus II MR and SR, respectively[6] In Taxus IV, 9 month f
The Algol System SZ Herculis: Physical Nature and Orbital Behavior
Jae Woo Lee,Chung-Uk Lee,Seung-Lee Kim,Ho-Il Kim,Jang-Ho Park
Physics , 2011, DOI: 10.1088/0004-6256/143/2/34
Abstract: Multiband CCD photometric observations of SZ Her were obtained between 2008 February and May. The light curve was completely covered and indicated a significant temperature difference between both components. The light-curve synthesis presented in this paper indicates that the eclipsing binary is a classical Algol-type system with parameters of $q$=0.472, $i$=87$^\circ$.57, and $\Delta$($T_{1}$--$T_{2}$)=2,381 K; the primary component fills approximately 77% of its limiting lobe and is slightly larger than the lobe-filling secondary. More than 1,100 times of minimum light spanning more than one century were used to study an orbital behavior of the binary system. It was found that the orbital period of SZ Her has varied due to a combination of two periodic variations with cycle lengths of $P_3$=85.8 yr and $P_4$=42.5 yr and semi-amplitudes of $K_3$=0.013 d and $K_4$=0.007 d, respectively. The most reasonable explanation for them is a pair of light-time effects (LITEs) driven by the possible existence of two M-type companions with minimum masses of $M_3$=0.22 M$_\odot$ and $M_4$=0.19 M$_\odot$, that are located close to the 2:1 mean motion resonance. If two additional bodies exist, then the overall dynamics of the multiple system may provide a significant clue to the formation and evolution of the eclipsing pair.
The Light and Period Variations of the Eclipsing Binary AA Ursae Majoris
Jae Woo Lee,Chung-Uk Lee,Seung-Lee Kim,Ho-Il Kim,Jang-Ho Park
Physics , 2010, DOI: 10.1086/658170
Abstract: We present new multiband CCD photometry for AA UMa made on 8 nights between January and March 2009; the $R$ light curves are the first ever compiled. Historical light curves, as well as ours, display partial eclipses and inverse O'Connell effects with Max I fainter than Max II. Among possible spot models, a cool spot on either of the component stars and its variability with time permit good light-curve representations for the system. A total of 194 eclipse timings over 81 yrs, including our five timings, were used for ephemeris computations. We found that the orbital period of the system has varied due to a periodic oscillation overlaid on an upward parabolic variation. The continuous period increase at a fractional rate of $+$1.3$\times$10$^{-10}$ is consistent with that calculated from the W-D code and can be interpreted as a thermal mass transfer from the less to the more massive secondary star at a rate of 6.6$\times$10$^{-8}$ M$_\odot$ yr$^{-1}$. The periodic component is in satisfactory accord with a light-time effect due to an unseen companion with a period of 28.2 yrs, a semi-amplitude of 0.007 d, and a minimum mass of $M_3 \sin i_3$=0.25 $M_\odot$ but this period variation could also arise from magnetic activity.
Physical Nature and Timing Variations of the Eclipsing System V407 Pegasi
Jae Woo Lee,Jang-Ho Park,Kyeongsoo Hong,Seung-Lee Kim,Chung-Uk Lee
Physics , 2014, DOI: 10.1088/0004-6256/147/4/91
Abstract: New multiband CCD photometry is presented for V407 Peg; the $R_{\rm C}$ light curves are the first ever compiled. Our light curves, displaying a flat bottom at secondary minimum and an O'Connell effect, were simultaneously analyzed with the radial-velocity (RV) curves given by Rucinski et al. (2008). The light changes of the system are best modeled by using both a hot spot on the secondary star and a third light. The model represents historical light curves also. All available minimum epochs, including our six timing measurements, have been examined and indicate that the eclipse timing variation is mainly caused by light asymmetries due to the spot activity detected in the light-curve synthesis. The hot spot may be produced as a result of the impact of the gas stream from the primary star. Our light and velocity solutions indicate that V407 Peg is a totally-eclipsing A-type overcontact binary with values of $q$=0.251, $i$=87$^\circ.6$, $\Delta T$=496 K, $f$=61 $\%$, and $l_3$=11$\sim$16 $\%$. Individual masses and radii of both components are determined to be $M_1$=1.72 M$_\odot$, $M_2$=0.43 M$_\odot$, $R_1$=2.15 R$_\odot$, and $R_2$=1.21 R$_\odot$. These results are very different from previous ones, which is probably caused by the light curves with distorted and inclined eclipses used in those other analyses. The facts that there are no objects optically related with the system and that the seasonal RVs show a large discrepancy in systemic velocity indicate that the third light source most likely arises from a tertiary component orbiting the eclipsing pair.
The Light and Period Variations of the Eclipsing Binary BX Draconis
Jang-Ho Park,Jae Woo Lee,Seung-Lee Kim,Chung-Uk Lee,Young-Beom Jeon
Physics , 2012, DOI: 10.1093/pasj/65.1.1
Abstract: New CCD photometric observations of BX Dra were obtained for 26 nights from 2009 April to 2010 June. The long-term photometric behaviors of the system are presented from detailed studies of the period and light variations, based on the historical data and our new observations. All available light curves display total eclipses at secondary minima and inverse O'Connell effects with Max I fainter than Max II, which are satisfactorily modeled by adding the slightly time-varying hot spot on the primary star. A total of 87 times of minimum light spanning over about 74 yrs, including our 22 timing measurements, were used for ephemeris computations. Detailed analysis of the O-C diagram showed that the orbital period has changed in combinations with an upward parabola and a sinusoidal variation. The continuous period increase with a rate of +5.65 \times 10^-7 d yr^-1 is consistent with that calculated from the Wilson-Devinney synthesis code. It can be interpreted as a mass transfer from the secondary to the primary star at a rate of 2.74 \times 10^-7 M\odot yr^-1, which is one of the largest rates for contact systems. The most likely explanation of the sinusoidal variation with a period of 30.2 yrs and a semi-amplitude of 0.0062 d is a light-traveltime effect due to the existence of a circumbinary object. We suggest that BX Dra is probably a triple system, consisting of a primary star with a spectral type of F0, its secondary component of spectral type F1-2, and an unseen circumbinary object with a minimum mass of M3 = 0.23 M\odot.
SUrvey of Guideline Adherence for Treatment of Systolic Heart Failure in Real World (SUGAR): A Multi-Center, Retrospective, Observational Study
Byung-Su Yoo, Jaewon Oh, Bum-Kee Hong, Dae-Hee Shin, Jang-Ho Bae, Dong Heon Yang, Wan-Joo Shim, Hyung-seop Kim, Su-Hong Kim, Jin-Oh Choi, Woo-Jung Chun, Choong-Won Go, Hyun-Jae Kang, Sang Hong Baek, Jang-hyun Cho, Suk-Keun Hong, Joon-Han Shin, Seok-Kyu Oh, Wook-Bum Pyun, Jun Kwan, Young-Joon Hong, Jin-Ok Jeong, Seok-Min Kang, Dong-Ju Choi, on behalf of the SUGAR Study
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0086596
Abstract: Background Clinical practice guidelines have been slowly and inconsistently applied in clinical practice, and certain evidence-based, guideline-driven therapies for heart failure (HF) have been significantly underused. The purpose of this study was to survey guideline compliance and its effect on clinical outcomes in the treatment of systolic HF in Korea. Method and Results The SUrvey of Guideline Adherence for Treatment of Systolic Heart Failure in Real World (SUGAR) trial was a multi-center, retrospective, observational study on subjects with systolic HF (ejection fraction <45%) admitted to 23 university hospitals. The guideline adherence indicator (GAI) was defined as a performance measure on the basis of 3 pharmacological classes: angiotensin-converting enzyme inhibitor (ACEI) or angiotensin receptor II blocker (ARB), beta-blocker (BB), and aldosterone antagonist (AA). Based on the overall adherence percentage, subjects were divided into 2 groups: those with good guideline adherence (GAI ≥50%) and poor guideline adherence (GAI <50%). We included 1319 regional participants as representatives of the standard population from the Korean national census in 2008. Adherence to drugs at discharge was as follows: ACEI or ARB, 89.7%; BB, 69.2%; and AA, 65.9%. Overall, 82.7% of the patients had good guideline adherence. Overall mortality and re-hospitalization rates at 1 year were 6.2% and 37.4%, respectively. Survival analysis by log-rank test showed a significant difference in event-free survival rate of mortality (94.7% vs. 89.8%, p = 0.003) and re-hospitalization (62.3% vs. 56.4%, p = 0.041) between the good and poor guideline-adherence groups. Conclusions Among patients with systolic HF in Korea, adherence to pharmacologic treatment guidelines as determined by performance measures, including prescription of ACEI/ARB and BB at discharge, was associated with improved clinical outcomes.
Long-term Photometric Behavior of the Eclipsing Binary GW Cephei
Jae Woo Lee,Jae-Hyuck Youn,Wonyong Han,Chung-Uk Lee,Seung-Lee Kim,Ho-Il Kim,Jang-Ho Park,Robert H. Koch
Physics , 2009, DOI: 10.1088/0004-6256/139/3/898
Abstract: New CCD photometry during 4 successive years from 2005 is presented for the eclipsing binary GW Cep, together with reasonable explanations for the light and period variations. All historical light curves, obtained over a 30-year interval, display striking light changes, and are best modeled by the simultaneous existence of a cool spot and a hot spot on the more massive cool component star. The facts that the system is magnetically active and that the hot spot has consistently existed on the inner hemisphere of the star indicate that the two spots are formed by (1) magnetic dynamo-related activity on the cool star and (2) mass transfer from the primary to the secondary component. Based on 38 light-curve timings from the Wilson-Devinney code and all other minimum epochs, a period study of GW Cep reveals that the orbital period has experienced a sinusoidal variation with a period and semi-amplitude of 32.6 yrs and 0.009 d, respectively. In principle, these may be produced either by a light-travel-time effect due to a third body or by an active magnetic cycle of at least one component star. Because we failed to find any connection between luminosity variability and the period change, that change most likely arises from the existence of an unseen third companion star with a minimum mass of 0.22 $M_\odot$ gravitationally bound to the eclipsing pair.
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