Ki Hoon Kim

Effects of ceria in CO2 reforming of methane over Ni/calcium hydroxyapatite

In CO2 reforming of methane over a calcium hydroxyapatite-supported nickel catalyst, the carbon deposition occurred more severely with increase of the methane partial pressure and at temperatures below about 1,000 K. The effects of ceria that was added as a promoter to the nickel catalyst were investigated. It was observed that the ceria not only enhanced the catalyst stability but also increased the activity, and this is considered owing to the oxygen storage capacity of ceria. The TGA analysis demonstrated that the ceria promoted the removal of the deposited carbon. The optimum Ce/Ni mole ratio was ca. 0.3/2.5. The deposited carbon could easily be removed by oxygen treatment at 1,023 K and the catalytic activity could be restored.

A real-time finite line detection system based on FPGA

Image processing and analysis are active research topics. An intelligent vehicle and a service robot require these techniques. In particular, there is a big demand for line detection because it has a wide range of applications. The line features in an image are used for object identification, robot navigation, and intelligent vehicle control. To detect the lines, a Hough transform is generally used. The Hough transform has good detection results and it is robust to noise, but it takes a long time to execute and it requires a great deal of memory to store the parameter space. This paper proposes a dedicated line detection hardware system. To increase the processing speed, it has a parallel Hough transform unit, and it partitions the parameter space to decrease the memory requirements. It can detect not only the line parameters, but also the exact start and end points of each line, and it sorts these lines by length. It can display the detected line on a monitor via the DVI interface. This system is designed with VHDL and implemented on an XC4VLX200 FPGA. The device usage is about 15% and the maximum clock frequency is 67 MHz. It can detect up to 256 lines in one image frame and it can process up to 149 frames per second. The simulation and real experimental results are given to verify the system performance.

Promotion effects of ceria in partial oxidation of methane over Ni-calcium hydroxyapatite

Effects of ceria added as a promoter to a nickel-calcium hydroxyapatite catalyst, which has recently been reported to exhibit high activity and selectivity in partial oxidation of methane, were investigated. The ceria-promoted catalyst exhibited higher activity and stability than the unpromoted one. This is considered due to the oxygen storage capacity of ceria, which promotes easier removal of the deposited carbon. The optimum content of ceria was determined to lie in the range of the Ce/Ni ratio from 0.1/2.5 to 0.2/2.5.

Predictors and clinical outcomes of persistent methicillin-resistant Staphylococcus aureus bacteremia: a prospective observational study.

Background/Aims The high mortality attributable to persistent methicillin-resistant Staphylococcus aureus (MRSA) bacteremia in spite of glycopeptide treatment has heightened the need for early detection and intervention with alternative agents. The purpose of this study was to determine the clinical characteristics of and risk factors for persistent MRSA bacteremia. Methods All first episodes of significant MRSA bacteremia at a 710-bed academic medical center from November 2009 through August 2010 were recorded. Blood cultures were conducted at 3 days and every 2 to 3 days thereafter until clearance. Clinical characteristics and outcomes were compared between persistent MRSA bacteremia (≥ 7 days) and nonpersistent MRSA bacteremia (≤ 3 days). Results Of 79 patients with MRSA bacteremia during the study period, 31 (39.2%) had persistent MRSA bacteremia. The persistent MRSA bacteremia group had significantly higher 30-day mortality than the nonpersistent MRSA bacteremia group (58.1% vs. 16.7%, p < 0.001). Multivariate analysis indicated that metastatic infection at presentation (odds ratio [OR], 14.57; 95% confidence interval [CI], 3.52 to 60.34; p < 0.001) and delayed catheter removal in catheter-related infection (OR, 3.80; 95% CI, 1.04 to 13.88; p = 0.004) were independent predictors of persistent MRSA bacteremia. Patients with a time to blood culture positivity (TTP) of < 11.8 hours were at increased risk of persistent MRSA bacteremia (29.0% vs. 8.3%, p = 0.029). Conclusions High mortality in patients with persistent MRSA bacteremia was noted. Early detection of metastatic infection and early removal of infected intravascular catheters should be considered to reduce the risk of persistent MRSA bacteremia. Further studies are needed to evaluate the role of TTP for predicting persistent MRSA bacteremia.

Noncompaction of the myocardium coexistent with bronchiectasis and polycystic kidney disease.

Noncompaction of the ventricular myocardium (NCM) is a disorder of unknown aetiology characterised by numerous, prominent ventricular trabeculations and deep intertrabecular recesses. Polycystic kidney disease (PKD) is characterised by the formation of multiple cysts in the kidneys and liver and, less frequently, in the pancreas. Cardiovascular abnormalities in PKD involve hypertension, mitral valve prolapse, intracranial aneurysms and pulmonary abnormalities include primary ciliary dyskinesia and bronchiectasis. Several case reports have described the possible association between PKD and NCM. However, NCM, PKD and bronchiectasis have not previously been correlated. This is the first case of NCM coupled with PKD and bronchiectasis.

Rare case of an unroofed coronary sinus

Unroofed coronary sinus (CS) is a rare congenital cardiac anomaly described by a communication between the CS and the left atrium due to the partial or complete absence of the CS roof. Echocardiography is the most widely used imaging modality for suspected unroofed CS, but it is limited in its ability to visualize the posterior cardiac structures. Multidetector computed tomography has allowed the visualization and accurate anatomic and morphologic evaluation of these structures. We report a rare case of unroofed CS found incidentally in a 41-year-old man who was studied by echocardiography and multidetector computed tomography.

Dedicated parallel thinning architecture based on FPGA

Thinning is a widely used image processing method which can extract feature parameters from an image. Because of the time complexity caused by repetitive operations of thinning algorithm, many approaches have been done to obtain real-time performance. However, previous thinning algorithms have several limitations for thinning large volumes of data in the processing time aspect. This paper presents parallel thinning architecture and its FPGA-based implementation which can process thinning in real-time. The proposed system is evaluated using large volumes of real-world data and verified its real-time performance.

Esophageal achalasia compressing left atrium diagnosed by echocardiography using a liquid containing carbon dioxide in a 21-year-old woman with Turner syndrome

Extrinsic compression of the left atrium by the esophagus, the stomach, or both is an uncommon but important cause of hemodynamic compromise. Achalasia is a motility disorder characterized by impaired relaxation of the lower esophageal sphincter and dilatation of the distal two thirds of the esophagus. Echocardiographic imaging after oral ingestion of liquid containing carbon dioxide allowed for differentiation between a compressive vascular structure and the esophagus. We report a rare case of esophageal achalasia compressing the left atrium diagnosed by echocardiography using a liquid containing carbon dioxide in a 21-year-old woman with Turner syndrome.