Kyung-Hee Cho

Effects of oxygen pressure and Mn-doping on the electrical and dielectric properties of Bi5Nb3O15 thin film grown by pulsed laser deposition

Bi5Nb3O15 (B5N3) thin films grown at temperatures above 500 °C developed a crystalline B5N3 phase that decomposed into a BiNbO4 phase in the film grown at 700 °C, probably due to Bi2O3 evaporation. The leakage current density of the B5N3 film grown at 200 °C under an oxygen pressure (OP) of 100 mTorr was high at approximately 6.3 × 10−7 A cm−2 at 0.2 MV cm−1, with a small breakdown field of 0.24 MV cm−1 due to the presence of intrinsic oxygen vacancies. The electrical properties of the B5N3 films improved with increasing OP during the growth but the dielectric constant (er) decreased. The Mn-doping also improved the electrical properties of the B5N3 films grown under low OP by producing doubly ionized oxygen vacancies, which decreased the number of the intrinsic oxygen vacancies. Furthermore, the Mn-doping increased the er value of the B5N3 film, confirming the effectiveness of such doping in improving both the electrical and the dielectric properties of the B5N3 film. In particular, the 5.0 mol% Mn-doped B5N3 film grown at 200 °C under an OP of 100 mTorr exhibited a low leakage current density of 7.9 × 10−8 A cm−2 at 0.2 MV cm−1 and a large breakdown field of 0.4 MV cm−1 with a high er of 64.

Effective behavior signature extraction method using sequence pattern algorithm for traffic identification

Summary With the rapid development of the internet and a vigorous emergence of new applications, traffic identification has become a key issue. Although various methods have been proposed, there are still several limitations to achieving fine-grained and application-level identification. Therefore, we previously proposed a behavior signature model for extracting a unique traffic pattern of an application. Although this signature model achieves a good identification performance, it has trouble with the signature extraction, particularly from a huge amount of input traffic, because a Candidate-Selection method is used for extracting the signature. To improve this inefficiency in the extraction process, in this paper, we propose a novel behavior signature extraction method using a sequence pattern algorithm. The proposed method can extract a signature regardless of the volume of input traffic because it excludes certain unsatisfactory candidates using a predefined support value during the early stage of the process. We proved experimentally the feasibility of the proposed extraction method for 7 popular applications.

Design and Rationale of the Intima-Medial Thickness Sub-Study of the PreventIon of CArdiovascular Events in iSchemic Stroke Patients with High Risk of Cerebral hemOrrhage (PICASSO-IMT) Study

BACKGROUND Atherosclerosis is one of the main mechanisms of stroke and cardiovascular diseases and is associated with increased risk of recurrent stroke and cardiovascular events. Intima-medial thickness (IMT) is a well-known surrogate marker of atherosclerosis and has been used to predict stroke and cardiovascular events. However, the clinical significance of IMT and IMT change in stroke has not been investigated in well-designed studies. The PreventIon of CArdiovascular events in iSchemic Stroke patients with high risk of cerebral hemOrrhage-Intima-Media Thickness (PICASSO-IMT) sub-study is designed to investigate the effects of cilostazol, probucol, or both on IMT in patients with stroke. METHODS PICASSO-IMT is a prospective sub-study of the PICASSO study designed to measure IMT and plaque score at 1, 13, 25, 37, and 49 months after randomization. RESULTS The primary outcome is the change in mean carotid IMT, which is defined as the mean of the far-wall IMTs of the right and left common carotid arteries, between baseline and 13 months after randomization. CONCLUSION PICASSO-IMT will provide the largest IMT data set in a stroke population and will provide valuable information about the clinical significance of IMT in patients with ischemic stroke.