Software reliability model for open-source software that considers the number of finite faults and dependent faults.

Software has become a vital factor in the fourth industrial revolution. Owing to the increase in demand for software products in various fields (big data, artificial intelligence, the Internet of Things, etc.), the software industry has expanded more than ever before. Therefore, software reliability has become very important, and efforts are being made to increase it. One of these efforts is the development of software reliability models (SRMs). SRMs have been studied for a long time as a model that predicts software reliability by using the number of software faults. Software failures can occur for several reasons, including independent software faults such as code errors and software hangs, as well as dependent cases where code errors lead to other software faults. Recently, due to the diversity of software operating environments, software faults are more likely to occur in a dependent manner, and, for this reason, they are likely to increase rapidly from the beginning and progress slowly to the maximum number thereafter. In addition, many large companies have focused on open-source software (OSS) development, and OSS is being developed by many users. In this study, we propose a new SRM that considers the number of finite faults and dependent faults, and examine the goodness-of-fit of a new SRM and other existing non-homogeneous Poisson process models based on the OSS datasets. Through numerical examples, the proposed model demonstrated a significantly better goodness-of-fit when compared to other existing models, and it also exhibited better results on the newly proposed integrated criteria.

Forecasting COVID-19 Confirmed Cases Using Empirical Data Analysis in Korea.

From November to December 2020, the third wave of COVID-19 cases in Korea is ongoing. The government increased Seoul's social distancing to the 2.5 level, and the number of confirmed cases is increasing daily. Due to a shortage of hospital beds, treatment is difficult. Furthermore, gatherings at the end of the year and the beginning of next year are expected to worsen the effects. The purpose of this paper is to emphasize the importance of prediction timing rather than prediction of the number of confirmed cases. Thus, in this study, five groups were set according to minimum, maximum, and high variability. Through empirical data analysis, the groups were subdivided into a total of 19 cases. The cumulative number of COVID-19 confirmed cases is predicted using the auto regressive integrated moving average (ARIMA) model and compared with the actual number of confirmed cases. Through group and case-by-case prediction, forecasts can accurately determine decreasing and increasing trends. To prevent further spread of COVID-19, urgent and strong government restrictions are needed. This study will help the government and the Korea Disease Control and Prevention Agency (KDCA) to respond systematically to a future surge in confirmed cases.

Conjugated polymer chain and crystallite orientation induced by vertically aligned carbon nanotube arrays.

We report a method for controlling the orientations of conjugated polymers in the active layer of organic thin-film transistors (OTFTs) by annealing the film at the melting temperature in a vertically aligned multiwalled carbon nanotube (VA-CNT) template under various load pressures. Poly(3-hexylthiophene) [P3HT] molecules are effectively aligned in the melting state annealing at 240 °C for 30 min, as a result of intermolecular π-π and CH3-π interactions between the polymer and the VA-CNTs, which are separated from the conjugated polymer film after cooling to room temperature. In-plane and out-of-plane X-ray diffraction results show that the melt-annealed P3HT film with VA-CNTs has better crystallite ordering than a pristine 80 °C baked film and a melt-annealed film without VA-CNTs, and a larger number of crystallites in the treated P3HT film are oriented in the [100] direction, which is normal to the substrate. When we used the melt-aligned P3HT film with VA-CNTs as the active layer in OTFTs, the P3HT OTFT exhibits a better field-effect mobility value of 0.12 cm(2)/(V s) than a simply melt-annealed device without VA-CNTs [0.06 cm(2)/(V s)].

Out-of-plane growth of CNTs on graphene for supercapacitor applications.

This paper describes the fabrication and characterization of a hybrid nanostructure comprised of carbon nanotubes (CNTs) grown on graphene layers for supercapacitor applications. The entire nanostructure (CNTs and graphene) was fabricated via atmospheric pressure chemical vapor deposition (APCVD) and designed to minimize self-aggregation of the graphene and CNTs. Growth parameters of the CNTs were optimized by adjusting the gas flow rates of hydrogen and methane to control the simultaneous, competing reactions of carbon formation toward CNT growth and hydrogenation which suppresses CNT growth via hydrogen etching of carbon. Characterization of the supercapacitor performance of the CNT-graphene hybrid nanostructure indicated that the average measured capacitance of a fabricated graphene-CNT structure was 653.7 µF cm(-2) at 10 mV s(-1) with a standard rectangular cyclic voltammetry curve. Rapid charging-discharging characteristics (mV s(-1)) were exhibited with a capacitance of approximately 75% (490.3 µF cm(-2)). These experimental results indicate that this CNT-graphene structure has the potential towards three-dimensional (3D) graphene-CNT multi-stack structures for high-performance supercapacitors.

Structural and electrochemical properties of Ag nano-dots combined amorphous Si electrodes for thin-film lithium rechargeable batteries.

We have one-pot fabricated Si-based nanocomposite electrodes containing Ag nano-dots for thin-film Li rechargeable batteries by a co-sputtering method. The structural and electrochemical properties of the Si/Ag nanocomposite electrodes are investigated via transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and cycler. The TEM and XRD results show that crystalline Ag nano-dots (approximately 5-9 in size) are well-dispersed within an amorpohous Si matrix. It is shown that the Si/Ag nanocomposite electrode shows much better structural stability than the Si only sample. It is also shown that the Si/Ag nanocomposite electrode shows superior capacity retention compared to the Si only electrode. The results indicate that the presence of the Ag nano-dots is important minimizing the formation of cracks in the electrode, so leading to the better life-time for thin-film Li rechargeable batteries.

Diameter-engineered SnO2 nanowires over contact-printed gold nanodots using size-controlled carbon nanopost array stamps.

A novel and effective methodology to control the diameters of semiconductor nanowires is reported through a versatile contact-printing method for obtaining size-controlled nanocatalysts by size-tunable carbon-based nanometer stamps. Vertically aligned carbon nanopost arrays, derived from nanoporous alumina templates, are used as the nanoscale stamps for printing of catalyst nanoparticles. The diameter of the carbon nanopost can be engineered by adjusting the pore dimension of the templates. Over the contact-printed Au nanodots in a uniform size distribution, semiconductor SnO2 nanowires are grown via a vapor-liquid-solid growth mechanism. Consequently, a direct dimension correspondence is achieved between the carbon nanopost stamp, the printed Au catalyst, and the finally obtained SnO2 nanowires. A model example of the diameter-dependent electrical properties of the semiconductor nanowires is successfully demonstrated in this work by applying three diameter-controlled SnO2 nanowires to nanowire field effect transistors.

Carbon nanosyringe array as a platform for intracellular delivery.

We report a novel platform for intracellular delivery of genetic material and nanoparticles, based on vertically aligned carbon nanosyringe arrays (CNSAs) of controllable height. Using this technology, we have shown that plasmid and quantum dots can be efficiently delivered to the cytoplasm of cancer cells and human mesenchymal stem cells. The CNSA platform holds great promise for a myriad of applications including cell-based therapy, imaging, and tracking in vivo, and in biological studies aimed at understanding cellular function.

Patterned array of nanoparticles on substrates via contact printing method with CNTs/AAO stamp.

Patterned arrays of Fe oxide nanoparticles were transferred via contact printing method on a substrate surface using carbon nanotubes embedded in anodic aluminum oxide (CNTs/AAO) as a stamp, in which vertically aligned CNTs in hexagonally patterned array was first fabricated by chemical vapor deposition into the AAO, followed by a partial chemical etching to expose the CNTs from the AAO. Fe precursor inked CNTs stamp was contact-printed on a Pt-coated Si substrate, and after heat treatment at 200 degrees C, patterned array of Fe oxide nanoparticles with ca. 80 nm of diameter and ca. 120 nm of inter-distance between the nanoparticles was consequently obtained.

Effects of tanshinone IIA on the hepatotoxicity and gene expression involved in alcoholic liver disease.

Tanshinone IIA is one of the most abundant constituents of the root of Salvia miltiorrhiza BUNGE which exerts antioxidant and anti-inflammatory actions in many experimental disease models. In the present study, we demonstrated that the standardized fraction of S. miltiorrhiza (Sm-SF) was able to protect RAW 264.7 cells from ethanol-and lipopolysaccharide (LPS)-induced production of superoxide radical, activation of NADPH oxidase and subsequently death of the cells. Among four main components of Sm-SF, tanshinone IIA was the most potent in protecting cells from LPS-and ethanol-induced cytotoxicity. LPS or ethanol induced the expression of CD14, iNOS, and SCD1 and decreased RXR-alpha, which was completely reversed by tanshinone IIA. In H4IIEC3 cells, 10 microM tanshinone IIA effectively blocked ethanol-induced fat accumulation as evidenced by Nile Red binding assay. These results indicate that tanshinone IIA may have potential to inhibit alcoholic liver disease by reducing LPS-and ethanol-induced Kupffer cell sensitization, inhibiting synthesis of reactive oxygen/nitrogen species, inhibiting fatty acid synthesis and stimulating fatty acid oxidation.

Size controlled nickel oxide nanoparticles on carbon nanotubes for supercapacitor electrode.

We have synthesized supercapacitor electrodes fashioned of NiO(x)/multiwalled carbon nanotubes (MWNTs), in which the controlled NiO(x) nanoparticles were prepared via a simple colloidal method and supported on the MWNTs. The sizes of the NiO(x) nanoparticles on MWNTs were systematically varied from 4 to 14 nm at a fixed metal loading of 20 wt% by changing sintering temperature in a controlled manner. The maximum specific capacitance of the NiO(x)/MWNTs was measured to be ca. 215 F per unit gram of NiO(x)/MWNTs by cyclic voltammetry (CV) in an aqueous 1 M KOH electrolyte, demonstrating that the specific capacitance of the MWNTs-supported nanosize NiO(x) is strongly dependent on the dispersion and size of the nanoparticles for the supercapacitor performance.

Nanoimprint lithography patterns with a vertically aligned nanoscale tubular carbon structure.

A nanoscale tubular carbon structure array was demonstrated as a mold for nanoimprint lithography (NIL), in which a vertically formed and hexagonally aligned nanoscale tubular carbon array was fabricated through carbon growth inside an anodic aluminum oxide (AAO) nanotemplate, followed by controlled chemical etching of the AAO layer. High density (over 10(10) cm(-2)) of the nanoscale carbon pillars with their controlled diameters and protruded lengths was inversely replicated onto a UV-curable resist for the first time using the imprinting lithography technique.

Magnetic dipolar interaction in NiFe nanodot arrays formed on vertical carbon nanotubes.

A new and simple method for the fabrication of densely packed magnetic nanodot arrays was developed using conventional sputtering deposition at room temperature. An anodized alumina template was employed for the formation of nanodot assemblies, consisting of carbon nanotubes (CNTs) and magnetic nanodot arrays. Each nanodot was formed exactly on top of a CNT and was arranged with a well-ordered structure in a wide range of area. It was also found that the size of dots and the distance between dots can be tailored by changing the length of CNTs, inducing a change of strength of dipolar interaction between nanodots.

Ta2O5-Incorporated WO3 nanocomposite film for improved electrochromic performance in an acidic condition.

We report electrochromic and electrochemical properties of a WO3-Ta2O5 nanocomposite electrode that was fabricated from co-sputtering. Transmission electron microscopy (TEM) images of the WO3-Ta20 nanocomposite electrode revealed that morphology of the WO3 film was changed by incorporation of Ta2O5 nanoparticles, and their chemical states were confirmed to be W6+ and Ta5+ oxides from X-ray photoelectron spectroscopy (XPS). The introduction of Ta2O5 to the WO3 film played a role in alleviating surface roughness increase during continuous potential cycling; whereas the surface roughness of the WO3 film was increased from ca. 3.0 nm to ca. 13.4 nm after 400 cycles, the roughness increase on the WO3-Ta2O5 was significantly reduced to 4.2 nm after 400 cycles, as investigated by atomic force microscopy (AFM). This improvement of the stability by adding Ta2O5 may be responsible for the enhanced electrochemical and optical properties over long-term cycling with the WO3-Ta2O5 nanocomposite electrode.

Use of Sn-Si nanocomposite electrodes for Li rechargeable batteries.

The relationship between the structural properties of Sn nano-dots embedded in a Si electrode synthesised by co-sputtering and their electrochemical performance during a lithium insertion and extraction process has been investigated.