Minsu Kim

SHORT-PERIOD VARIABILITY SURVEY (SPVS) IN BOAO

We have been performing a wide-field photometric monitoring program, named SPVS (Short-Period Variability Survey), at the Bohyunsan Optical Astronomy Observatory (BOAO). The observation system consists of a small refracting telescope (D

Effect of patent foramen ovale closure for prevention on recurrent stroke or transient ischemic attack in selected patients with cryptogenic stroke

OBJECTIVES This study was sought to evaluate the effectiveness of patent foramen ovale (PFO) closure in selected patients (PFO shunt grade more than moderate) with cryptogenic stroke (CS). BACKGROUND Whether closure of PFO is an effective treatment for prevention of CS is still unclear. METHODS Consecutive 158 patients (mean age: 49.9 years old, closure group: 67 patients, medication group: 91 patients) were enrolled. The primary end point was a composite of recurrent stroke and transient ischemic attack. RESULTS Baseline characteristics were similar between the two groups, except age which was younger in the closure group (47.7 ± 10.8 vs 51.9 ± 9.9, P = 0.013), and the presence of shunt at rest was more common in the closure group (35.8% vs 10.4%, P = 0.000). Procedural success was 94.0%. Over a mean follow-up of 27.8 months, a total of six primary end point, all of which were strokes, occurred only in the medication group (6.6% vs 0%, P = 0.039). Stroke-free survival rate was significantly higher in the closure group (P = 0.026) CONCLUSIONS: Our study showed that PFO closure may be an effective treatment strategy to prevent recurrent stroke or TIA for patients with CS if it is conducted in selective patients who have PFO shunt more than moderate grade.

Thrombotic Occlusion of Stent Graft Limbs due to Severe Angulation of Aortic Neck in Endovascular Repair of Abdominal Aortic Aneurysm.

Endovascular aneurysm repair (EVAR) is a safe alternative to open surgical repair for an abdominal aortic aneurysm. However, unfavorable aortic anatomy of the aneurysm has restricted the widespread use of EVAR. Anatomic limitation is most often related to characteristics of the proximal neck anatomy. In this report, we described a patient with a severely angulated proximal neck who underwent EVAR, but required repeat intervention because of thrombotic occlusion of stent graft limbs.

Effects of Thickness on Structural and Optical Properties of ZnO Thin Films Fabricated by Spin Coating Method

스핀코팅 방법을 이용하여 다양한 농도의 전구체로 ZnO 나노 섬유질 박막(ZnO nano-fibrous thin films)을 성장하였고, 그에 따른 표면 및 광학적 특성 변화를 scanning electron microscopy (SEM)와 photoluminescence (PL)을 이용하여 측정하였다. 전구체 농도가　0.4 mol (M) 이하 일 때는 성장률이 낮아 ZnO 핵생성만이 되었고, 0.6 M 이상일 때 ZnO 박막은 나노 섬유질 구조가 되었다. 전구체 농도가 더욱 증가함에 따라 ZnO 나노 섬유질의 굵기가 굵어졌고 ZnO 박막의 두께도 단계적으로 두꺼워졌다. 전구체 농도가 증가함에 따라 ZnO 나노 섬유질 박막의 photoluminescence (PL)의 근밴드가장자리 광방출 (near-band-edge emission) 피크 세기와 full-width at half-maximu (FWHM)이 증가하였고, 깊은 준위 광방출(deeplevel emission) 피크는 적색편이(red-shift)하였다.Thickness effects on the structural and optical properties of ZnO thin films fabricated by spin coating method have been carried out. With increase in the thickness of the ZnO thin films, the width and density of striation shape are increased. The ZnO thin film with thickness of 450 nm has a smooth surface morphology. For the ZnO thin film with a smooth surface, orientation factor is sharply increased and FWHM of (002) diffraction peak is decreased compared to the ZnO thin films with a striation shape surface. Thickness and surface morphology of the ZnO thin films hardly affect the NBE peak position. However, the DLE peak position is blue-shifted as the surface morphology is changed from striation to smooth surface. The PL intensity ratio of the NBE to DLE is increased and the FWHM of NBE peak is decreased as the thickness of the ZnO thin films is increased.

Improved early risk stratification of patients with ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention using a combination of serum soluble ST2 and NT-proBNP

Background Although soluble suppression of tumorigenicity 2 (sST2) in serum is known to be associated with ischemic heart disease and heart failure, data regarding its prognostic impact in ST-segment elevation myocardial infarction (STEMI) is limited. We evaluated the prognostic impacts of serum sST2 and other serum biomarkers in STEMI patients undergoing primary percutaneous coronary intervention (PCI). Methods Consecutive all 323 patients with STEMI that underwent primary PCI were enrolled. Blood tests and samples were obtained in an emergency room. The primary endpoint was 1-year major adverse cardiovascular and cerebrovascular events (MACCEs), defined as a composite of cardiovascular death, non-fatal MI, non-fatal stroke, and ischemia-driven revascularization. Results Mean age was 59.1±13.1 years (men 84%). MACCE (20 cardiovascular deaths, 7 non-fatal MI, 4 non-fatal stroke, 7 ischemia-driven revascularizations) occurred in 38 patients (12%). After adjusting for confounding factors, Cox regression analysis revealed that high serum sST2 (>75.8 ng/mL mean value, adjusted hazard ratio 2.098, 95% CI 1.008–4.367, p = 0.048) and high serum NT-proBNP level (>400 pg/mL, adjusted hazard ratio 2.606, 95% CI 1.086–6.257, p = 0.032) at the time of presentation independently predicted MACCE within a year of primary PCI. Furthermore, when high serum sST2 level was combined with high serum NT-proBNP level, the hazard ratio of MACCE was highest (adjusted hazard ratio 7.93, 95% CI 2.97–20.38, p<0.001). Conclusion Elevated serum levels of sST2 or NT-proBNP at the time of presentation were found to predict 1-year MACCE independently and elevated serum levels of sST2 plus NT-proBNP were associated with even poorer prognosis in patients with STEMI undergoing primary PCI.

Pregnancy in Hypertrophic Cardiomyopathy with Severe Left Ventricular Outflow Tract Obstruction

Hypertrophic obstructive cardiomyopathy (HOCM) patients with severe left ventricular outflow tract (LVOT) obstruction (those with a gradient of > 100 mm Hg) are at the highest risk of hemodynamic deterioration during pregnancy. Complications of HOCM include sudden cardiac death, heart failure, and arrhythmias. Physiological changes during pregnancy may induce these complications, affecting maternal and fetal health conditions. Therefore, close monitoring with appropriate management is essential for the well-being of both mother and fetus. We report on the case of a 27-year-old female patient with severe LVOT obstruction HOCM, pressure gradient (PG) of 125 mm Hg at resting, and 152 mm Hg induced by the Valsalva maneuver at 34 weeks gestation. This case showed how close monitoring using echocardiography and proper management during the course of pregnancy resulted in successful delivery in the patient with extremely high PG HOCM.

Effects of Current Density and Anodization Time on the Properties of Porous Si

The PS(porous Si) were fabricated with different anodization time and current density. The structural and optical properties of PS were investigated by SEM(scanning electron microscopy), AFM(atomic force microscopy), and PL(photoluminescence). It is found that the pore size and surface roughness of PS are proportional to the current density. The PL spectra show that the PL peak position is red-shifted with increasing anodization time. This behavior corresponds to the change of pore size which is consistent with the quantum confinement model. The FWHM(full width at half maximum) of PL peak is decreased from 97 to 51 nm and the PL peak position is blue-shifted with increasing current density up to 10 mA/. The PL peak intensity of the PS fabricated under 1 mA/ is the highest among samples.

Effects of Substrate Cleaning on the Properties of GaAs Epilayers Grown on Si(100) Substrate by Molecular Beam Epitaxy

The GaAs epitaxial layers were grown on Si(100) substrates by molecular beam epitaxy (MBE) using the two-step method. The Si(100) substrates were cleaned with three different surface cleaning methods of vacuum heating, As-beam exposure, and Ga-beam deposition at the substrate temperature of in the MBE growth chamber. Growth temperature and thickness of the GaAs epitaxial layer were and , respectively. The surface structure and properties were investigated by reflection high-energy electron diffraction (RHEED), AFM (Atomic force microscope), DXRD (Double crystal x-ray diffraction), PL (Photoluminescence), and PR (Photoreflectance). From RHEED, the surface structure of GaAs epitaxial layer grown on Si(100) substrate with Ga-beam deposition is (). The GaAs epitaxial layer grown on Si(100) substrate with Ga-beam deposition has a high quality.

PROGNOSTIC VALUE OF SOLUBLE ST2 IN PATIENTS WITH ST-SEGMENT ELEVATION MYOCARDIAL INFARCTION UNDERGOING PRIMARY PERCUTANEOUS CORONARY INTERVENTION

Background: Soluble ST2 has shown to be an independent predictor for adverse outcome in heart failure. We evaluated the prognostic value of soluble ST2 in ST-segment elevation myocardial infarction (STEMI) patients undergoing primary percutaneous coronary intervention (PCI). Methods: A total of 323

PROGNOSTIC IMPACT OF ALKALINE PHOSPHATASE MEASURED AT THE TIME OF PRESENTATION IN PATIENTS UNDERGOING PRIMARY PERCUTANEOUS CORONARY INTERVENTION FOR ST-SEGMENT ELEVATION MYOCARDIAL INFARCTION

Background: Serum alkaline phosphatase (ALP) level has been shown to be a prognostic factor in several subgroups of patients via its promotion of vascular calcification. We aimed to investigate the prognostic impact of ALP level measured at the time of presentation on clinical outcomes in patient