Sang Hyun Lee

Collision prediction at intersection in sensor network environment

This paper presents several algorithms to predict collisions among vehicles at intersection, where the information about the movement of vehicles within interesting region is exchanged via sensor network and local broadcasting. We additionally propose algorithms to predict collisions at access road, which is important as well. Experiments show that these algorithms give very accurate results with about 0.5 average false warnings at access road on highway. In comparison with access road, they give relatively more false warning reports at intersection

Mitral Loop Cerclage Annuloplasty for Secondary Mitral Regurgitation: First Human Results

OBJECTIVESnThis is an early feasibility clinical test of mitral loop cerclage annuloplasty to treat secondary mitral valvexa0regurgitation.nnnBACKGROUNDnSecondary mitral regurgitation is characterized by cardiomyopathy, mitral annular enlargement, and leaflet traction contributing to malcoaptation. Transcatheter mitral loop cerclage applies circumferential compression to the mitral annulus by creating a loop through the coronary sinus across the interventricular septum, protecting entrapped coronary arteries from compression, and interactive annular reduction under echocardiographic guidance. This is the first human test of mitral loop annuloplasty.nnnMETHODSnFive subjects with severe symptomatic secondary mitral regurgitation underwent mitral loop cerclage, with echocardiographic and computed tomography follow-up over 6 months.nnnRESULTSnMitral loop cerclage was successful in 4 of 5 subjects and aborted in 1 of the 5 because of unsuitable septal coronary vein anatomy. Immediately and over 6 months, measures of both mitral valve regurgitation (effective orifice area and regurgitation fraction) and chamber dimensions (left atrial and left ventricular volumes) were reduced progressively and ejection fractions increased. Two with persistent and permanent atrial fibrillation spontaneously reverted to sinus rhythm during follow-up. One subject experienced a small myocardial infarction from an unrecognized small branch coronary occlusion. Another, experiencing cardiogenic shock at baseline, died of intractable heart failure after 6 weeks.nnnCONCLUSIONSnIn this first human test, mitral loop cerclage annuloplasty was successful in 4 of 5 attempts, caused reverse remodeling (reduction in secondary mitral regurgitation and heart chamber volumes), and suggested electrical remodeling (reversion of atrial fibrillation). Further evaluation is warranted.

Zn(II)-Co(III)-Fe(III) multi-metal cyanide complexes as highly active catalysts for ring-opening polymerization of propylene oxide

The nanoporous Prussian blue analogues M3[M(CN)6]2, where M is a divalent metal and M is a trivalent metal, are constructed from octahedral M3+(CN)6 3− complexes which are bridged into a simple cubic lattice by M ions. This creates a crystal consisting of alternating M and M ions connected through cyanide linkers resulting in “defect-free” pores without any unsaturated metal centers (Figure 1). The charge imbalance between the [M3+(CN)6] 3complex and the M ions causes disordered [M3+(CN)6] 3vacancies to occur at 1/3 of the M sites to maintain charge neutrality in the crystal. The unsaturated metal centers present in these materials have been hypothesized as high-binding energy sites for hydrogen, resulting in plausible hydrogen storage materials. A type of Prussian blue analogues base upon Zn3[Co(CN)6]2 framework, so called multi-metal cyanide (MMC) complexes, are also well-known catalyst for the ring-opening polymerization of propylene oxide (PO) to produce poly(propylene oxide) polyol (PPG), one of the main raw materials in a wide range of polyurethane applications. Recent improvements have made MMC catalysts much more attractive for commercial manufacture of polyether polyols since they give high-quality PPG products that have low unsaturation level (UL), narrow molecular weight distribution (MWD) and low viscosity, especially compared to conventional base catalysts. While MMC catalysts offer attractive advantages over most widely used base catalysts, they must be activated for a long time before the polymerization starts. This long induction period (IP), e.g. several hour, undercuts the economic advantage of MMC catalysts. In addition, heating the catalyst for a prolonged period at high polymerization temperature above 100 C may deactivate it completely. In this communication, we show our preliminary results how to tune the activity and IP of MMC-catalyzed PO polymerizations by changing catalyst formulations of the MMC catalysts.

Modified montmorillonite as a tuner of propylene oxide polymerization behavior catalyzed by double metal cyanide compound

Double metal cyanide (DMC) complexes base upon Zn3[Co(CN)6]2 framework are well-known catalyst for the polymerization of propylene oxide (PO) to produce poly(propylene oxide) polyol (PPG), one of the main raw materials in a wide range of polyurethane applications. Recent improvements have made DMC catalysts much more attractive for commercial manufacture of polyether polyols since they give high-quality PPG products that have low unsaturation level (UL) resulting in monols, narrow molecular weight distribution (MWD) and low viscosity, especially compared to conventional base catalysts such as KOH. While DMC catalysts offer attractive advantages over most widely used base catalysts, they must be activated for a long time before the polymerization starts. This long induction period (IP), e.g. several hour, increases cycle time and therefore undercuts the economic advantage of DMC catalysts. In addition, heating the catalyst for a prolonged period at high polymerization temperature above 100 C can reduce its activity or deactivate it completely. In this communication, we show our preliminary results how to tune polyol properties as well as activity and IP of DMC-catalyzed PO polymerizations by combining DMC catalyst with modified montmorillonite (m-MMT) as a simple external additive.

136 Synthesis of ultra-low monol polyether polyols by multi-metal catalysts

Abstract Polymerizations of propylene oxide (PO) have been carried out by using double metal cyanide (DMC) catalysts based on Zn 3 [Co(CN) 6 ] 2 . By using complexing agent during preparation of catalyst, the catalytic activity, initiation time, and the unsaturation level in polyether polyols could be tuned. The catalysts were characterized by x-ray photoelectron spectroscopy, infrared spectroscopy, and x-ray powder diffraction. 13 C NMR analysis showed that the polyols have a random distribution of the configurational sequences. The stress-strain curves of methylene diisocyanate/1,4-butanediol cured polyurethanes (PU) showed that the monol content of polyol showed a dramatic effect on the mechanical properties of PU.

Thrombolytic Therapy Complemented by ECMO: Successful Treatment for A Case of Massive Pulmonary Thromboembolism with Hemodynamic Collapse

Pulmonary thromboembolism (PTE) is a common clinical condition related to significant mortality. Furthermore, patients with PTE presenting with right heart thrombus show higher mortality due to rapid hemodynamic deterioration. But the optimal treatment of massive PTE is controversial although various methods have been developed and improved. Here, we presented a case of 56-yr-old woman with massive PTE showing hemodynamic collapse, who was successfully treated with extracorporeal membrane oxygenation (ECMO) adjunct to thrombolytic therapy even without thrombectomy. ECMO was useful for resuscitation and stabilization of the cardiopulmonary function. In conclusion, thrombolytic therapy complemented by ECMO may be an effective treatment option for acute massive PTE with hemodynamic instability. Graphical Abstract

Radiation Exposure in Coronary Angiography: A Comparison of Cineangiography and Fluorography.

Background and Objectives Coronary angiography (CAG) is the gold standard for diagnosing coronary artery disease. However, exposure to ionizing radiation delivered during CAG has various negative biological effects on humans. In this study, there was an evaluation of whether fluorography resulted in decreased radiation exposure, as compared with cineangiography. Subjects and Methods Fifty-five patients were prospectively enrolled and divided into two CAG groups, in accordance with the operators professional discretion: a conventional cineangiography group versus a fluorography group. Fluorography refers to the photography of fluoroscopic images that are retrospectively stored, e.g., using the Store fluoro function of the Siemens cardiac angiography system. The primary outcomes included the air kinetic energy released per unit mass {air kerma (AK) mGy} and the dose (kerma)-area product (DAP; µGy · m2), both measured using built-in software in the Siemens system. The secondary outcomes included the total procedure time and amount of contrast agent used with each CAG method. Results The total AK and DAP were significantly lower in the fluorography group (159.3±64.9 mGy and 1337.9±629.6 µGy · m2, respectively) than in the cineangiography group (326.9±107.5 mGy and 2341.1±849.9 µGy · m2, respectively; p=0.000 for both). The total procedure time (cineangiography vs. fluorography, 12.8±4.7 vs. 12.5±2.9 min; p=0.779) and contrast agent amount (136.1±28.3 vs. 126.3±25.7, p=0.214) were comparable between the two groups. Conclusion Fluorography is a useful method to decrease the radiation exposure in selected patients requiring CAG.

Prognostic Significance of Presenting Blood Pressure in Patients With ST-Elevation Myocardial Infarction Undergoing Percutaneous Coronary Intervention

BACKGROUNDnWe evaluated the impact of normal vs. high presenting blood pressure (BP) on clinical outcomes and cardiac function in patients with ST-elevation myocardial infarction (MI).nnnMETHODSnIn 11,292 patients, in-hospital mortality and major adverse clinical events (MACE; all-cause death, nonfatal MI, or any revascularization) during follow-up were compared between patients with normal (≥ 100 mm Hg and ≤ 139 mm Hg) and high (≥ 140 mm Hg) systolic BP at presentation.nnnRESULTSnCompared to patients with high BP, patients with normal BP had significantly higher in-hospital mortality (1.5% vs. 3.7%; P < 0.001), especially in those with prior hypertension, and higher rates of all-cause death (3.3% vs. 5.3%; P < 0.001) and MACE (9.8% vs. 11.8%; P = 0.04) during follow-up (median: 330 days). After multivariate adjustment, normal BP was associated with higher risk of in-hospital mortality (adjusted hazard ratio (HR) = 2.268; 95% confidence interval (CI) = 1.144-4.498; P = 0.019), but not all-cause death (adjusted HR = 0.956; 95% CI = 0.602-1.517) or MACE (adjusted HR = 0.935; 95% CI = 0.755-1.158). Left ventricular ejection fraction at baseline and follow-up was significantly lower in patients with normal BP (52% vs. 51%; P < 0.001 and 55% vs. 54%; P = 0.018, respectively).nnnCONCLUSIONSnOur findings indicate that patients with normal presenting BP, especially those with prior hypertension, exhibit higher in-hospital mortality and poorer cardiac function compared to patients with high BP. Although outcomes during follow-up did not differ, cardiac function was persistently poorer in patients who presented with normal BP.

ATRIAL FIBRILLATION CYCLE LENGTH MEASURED BY TRANSESOPHAGEAL ECHOCARDIOGRAPHY: A PREDICTOR FOR MAINTAINING SINUS RHYTHM AFTER DC CARDIOVERSION

Background: The atrial fibrillation cycle length (AFCL) measured by electrophysiologic study is well known parameter for the maintenance of sinus rhythm after DC cardioversion (DCCV) or ablation therapy. The aim of this study was to test whether a AFCL measured by transesophageal echocardiography (

Extraction of a Fully Deployed Coronary Stent during Retrieval of Another Dislodged Stent

Coronary stent dislodgement is a rare and serious complication of percutaneous coronary intervention and is associated with major adverse cardiac events. Successful retrieval of the stent is recommended in this situation because it is important for the prognosis. Recently, a patient was referred to our hospital with a dislodged coronary stent. When attempting to percutaneously extract the dislodged stent, a challenging situation was encountered, as the stent was entrapped and tightly entangled with another fully deployed coronary stent. Extraction of a fully deployed stent is generally prohibited as it may result in severe complications. Nevertheless, we extracted both the dislodged stent and the fully deployed stent, as a last resort. Herein, we report about this case. Our case highlights if the operator had a thorough understanding of the surrounding circumstances regarding the fully deployed coronary stent, successful extraction of the fully deployed coronary stent without any complications could be possible.