An Efficient and Secure m

Recent rapid developments in wireless and mobile IT technologies have led to their application in many real-life areas, such as disasters, home networks, mobile social networks, medical services, industry, schools, and the military. Business/work environments have become wire/wireless, integrated with wireless networks. Although the increase in the use of mobile devices that can use wireless networks increases work efficiency and provides greater convenience, wireless access to networks represents a security threat. Currently, wireless intrusion prevention systems (IPSs) are used to prevent wireless security threats. However, these are not an ideal security measure for businesses that utilize mobile devices because they do not take account of temporal-spatial and role information factors. Therefore, in this paper, an efficient and secure mobile-IPS (m-IPS) is proposed for businesses utilizing mobile devices in mobile environments for human-centric computing. The m-IPS system incorporates temporal-spatial awareness in human-centric computing with various mobile devices and checks users’ temporal spatial information, profiles, and role information to provide precise access control. And it also can extend application of m-IPS to the Internet of things (IoT), which is one of the important advanced technologies for supporting human-centric computing environment completely, for real ubiquitous field with mobile devices

CHANGES IN MUSCLE ACTIVITY PATTERN IN LOWER LIMB EXTREMITY DURING PEDALLING BY SADDLE HEIGHT

As a preliminary study for a preferential saddle height for cyclist, muscle activity pattern in lower limb extremity between preferred and higher saddle height during pedalling was compared. Seven cyclists performed 3 min sub-maximal pedalling under two different saddle heights. Range of motion (ROM) of muscle length, onset-timing of muscle activity, and amount of muscle activity in biceps femoris (BF), vastus lateralis (VL), gastrocnemius (GM), and tibialis anterior muscles (TA) were used to compare changes in muscle activity pattern due to saddle height. Results showed that there was a significant difference in ROM of VL and that of TA (

Ultrathin, polarization-independent, and focus-tunable liquid crystal diffractive lens for augmented reality

Despite the recent advances in augmented reality (AR), which has shown the potential to significantly impact on our daily lives by offering a new way to manipulate and interact with virtual information, minimizing visual discomfort due to the vergence-accommodation conflict remains a challenge. Emerging AR technologies often exploit focus-tunable optics to address this problem. Although they demonstrated improved depth perception by enabling proper focus cues, a bulky form factor of focus-tunable optics prevents their use in the form of a pair of eyeglasses. Herein, we describe an ultrathin, focus-tunable liquid crystal (LC) diffractive lens with a large aperture, a low weight, and a low operating voltage. In addition, we show that the polarization dependence of the lens, which is an inherent optical property of LC lenses, can be eliminated using birefringent thin films as substrates and by aligning the optical axes of the birefringent substrates and LC at a specific angle. The polarization independence eliminates the need for a polarizer, thus further reducing the form factor of the optical system. Next, we demonstrate a prototype of AR glasses with addressable focal planes using the ultrathin lens. The prototype AR glasses can adjust the accommodation distance of the virtual image, mitigating the vergence-accommodation conflict without substantially compromising the form factor or image quality. This research on ultrathin lens technology shows promising potential for developing compact optical displays in various applications.Comment: 23 pages, 9 figure

Topography-Guided Spreading and Drying of 6,13-bis(triisopropylsilylethynyl)-pentacene Solution on a Polymer Insulator for the Field-Effect Mobility Enhancement

We report on the enhancement of the field-effect mobility of solution-processed 6,13-bis(triisopropylsilylethynyl)-pentacene (TIPS-pentacene) by unidirectional topography (UT) of an inkjet-printed polymer insulator. The UT leads to anisotropic spreading and drying of the TIPS-pentacene droplet and enables to spontaneously develop the ordered structures during the solvent evaporation. The mobility of the UT-dictated TIPS-pentacene film (0.202 ± 0.012 cm2/Vs) is found to increase by more than a factor of two compared to that of the isotropic case (0.090 ± 0.032 cm2/Vs). The structural arrangement of the TIPS-pentacene molecules in relation to the mobility enhancement is described within an anisotropic wetting formalism. Our UT-based approach to the mobility enhancement is easily applicable to different classes of soluble organic field-effect transistors by adjusting the geometrical parameters such as the height, the width, and the periodicity of the UT of an inkjet-printed insulator

Observations of the Polar Ionosphere by the Vertical Incidence Pulsed Ionospheric Radar at Jang Bogo Station, Antarctica

Korea Polar Research Institute (KOPRI) installed an ionospheric sounding radar system called Vertical Incidence Pulsed Ionospheric Radar (VIPIR) at Jang Bogo Station (JBS) in 2015 in order to routinely monitor the state of the ionosphere in the auroral oval and polar cap regions. Since 2017, after two-year test operation, it has been continuously operated to produce various ionospheric parameters. In this article, we will introduce the characteristics of the JBS-VIPIR observations and possible applications of the data for the study on the polar ionosphere. The JBS-VIPIR utilizes a log periodic transmit antenna that transmits 0.5–25 MHz radio waves, and a receiving array of 8 dipole antennas. It is operated in the Dynasonde B-mode pulse scheme and utilizes the 3-D inversion program, called NeXtYZ, for the data acquisition and processing, instead of the conventional 1-D inversion procedure as used in the most of digisonde observations. The JBS-VIPIR outputs include the height profiles of the electron density, ionospheric tilts, and ion drifts with a 2-minute temporal resolution in the bottomside ionosphere. With these observations, possible research applications will be briefly described in combination with other observations for the aurora, the neutral atmosphere and the magnetosphere simultaneously conducted at JBS

Ecological connectivity analysis based on the fish community in Jeongan Stream

This study focused on the longitudinal connectivity analysis, based on fish communities in the aspect of spatial variations of 34 sites from upstream to downstream. The Fish Assessment Index (FAI), based on ecological guilds and species composition, was applied to compare the ecological health among the sampling sites. The total number of 35 fish species, were sampled during the study period with dominant species of Zacco platypus (35.4%) and Zacco koreanus (11.8%). Cluster analysis showed that all sites were categorized as 4 distinct group communities (A, B, C, D). Non-metric multidimensional scaling analysis showed distinct difference between upstream (A, B) and downstream groups (C, D). Indicator Value Analysis (IndVal method), conducted to identify indicator species within each group, indicated that the species favoring upstream environments Rhynchocypris oxycephalus for the Group A and Iksookimia koreensis for the Group B. In contrast, the analysis indicated that the species with a preference for downstream habitats Pseudogobio esocinus for the Group C and Carassius auratus for the Group D. Ecological health, based on the FAI scores, showed a declining pattern toward the downstream, along with an increasing proportion of tolerant species and omnivores within the fish community. Overall these findings suggest the compositions of fish communities, as four groups, were modified by the weir structures and organic matter, nutrient pollutions

Sol-gel Processed Yttrium-doped SnO2 Thin Film Transistors

Y-doped SnO2 thin film transistors were successfully fabricated by means of sol-gel process. The effect of Y concentration on the structural, chemical, and electrical properties of sol-gel-processed SnO2 films was investigated via GIXRD, SPM, and XPS; the corresponding electrical transport properties of the film were also evaluated. The dopant, Y, can successfully control the free carrier concentration by suppressing the formation of oxygen vacancy inside SnO2 semiconductors due to its lower electronegativity and SEP. With an increase of Ywt%, it was observed that the crystallinity and oxygen vacancy concentration decreased, and the operation mode of SnO2 thin film transistor changed from accumulation (normally on) to enhancement mode (normally off) with a positive Vth shift. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.1

Development of tricuspid regurgitation late after left-sided valve surgery: a single-center experience with long-term echocardiographic examinations

OBJECTIVES: This study sought to investigate the incidence and identify the predictors of significant tricuspid regurgitation (TR) development long after left-sided valve surgery. METHODS: Of 615 patients who underwent surgery for left-sided valve disease between 1992 and 1995, 335 patients without significant TR who completed at least 5 years of clinical and echocardiographic follow-up were enrolled. Late significant TR development was assessed by echocardiography with a mean follow-up duration of 11.6 +/- 2.1 years. RESULTS: Significant late TR was found in 90 patients (26.9%). Patients with late TR showed an advanced age (47.6 +/- 13.4 vs 44.3 +/- 13.2 years, P = .04), a higher prevalence of preoperative atrial fibrillation (83.3 vs 46.5%, P < .001), a greater left atrial dimension (56.9 +/- 13.2 vs 52.4 +/- 11.5 mm, P = .006), and a higher prevalence of prior valve surgery (40.0 vs 25.3%, P = .01). In addition, late TR occurred more frequently in patients who had undergone mitral valve surgery than in those who did not (93.3 vs 72.2%, P < .001). However, multivariate analysis showed that the presence of preoperative atrial fibrillation (odds ratio 5.37; 95% CI 2.71-10.65; P < .001) was the only independent factor of late TR development. Patients who developed late TR had a lower event-free survival rate than those who did not (P = .03). CONCLUSIONS: The development of significant TR long after left-sided valve surgery is not uncommon with an estimated incidence of 27% and is closely associated with a poor prognosis. The presence of preoperative atrial fibrillation was identified as the only independent predictor of the development of late TR