Development of quantification software using model-based segmentation of left ventricular myocardium in gated myocardial SPECT

Gated myocardial single photon emission computed tomography (SPECT) is being used for the diagnosis of coronary artery diseases. In this study, we developed new software for the quantification of volumes and ejection fraction (EF) on the gated myocardial SPECT data using a cylindrical model. Volumes and EF by developed software were validated by comparing with those quantified by quantitative gated SPECT (QGS) software. Cylinder model for left ventricular myocardium was used to eliminate background activity and count profiles across the myocardium were fitted to the Gaussian curve to determine the endocardial and epicardial boundary. End-diastolic volume (EDV), end-systolic volume (ESV) and EF were calculated using this boundary information. Gated myocardial SPECT was performed in 83 patients. EDV, ESV and EF values estimated using present method were compared to those obtained using the commercialized software QGS, and reproducibility in the parameter estimation was assessed. EF, EDV and ESV obtained using two methods were correlated well (correlation coefficients = 0.96, 0.96 and 0.98). The correlation between the parameters repetitively estimated from the same data set by an operator was very high (correlation coefficients = 0.96, 0.99 and 0.99 for EF, EDV and ESV). On the repeated acquisition, reproducibility was also high with correlation coefficients of 0.89, 0.97 and 0.98. The present software will be useful for the development of new parameters for describing the perfusion and function of the LV.     

User behaviour towards protective information technologies: the role of national cultural differences

Computer technologies that protect data and systems from viruses, unauthorized access, disruptions, spyware and other threats have become increasingly important in the globally networked economy and society. Yet little is known about user attitudes and behaviour towards this category of information technologies. Comparative studies across different cultures in this context are even rarer. In this study, we examine the cross-cultural differences between South Korea and the United States in user behaviour towards protective information technologies. We develop a theoretical model of user behaviour based on the framework of the theory of planned behaviour and national cultural dimensions and indices. We posit that cultural factors moderate the strength of the relationships in the behavioural model in the context of protective information technologies. The model was then empirically tested using structural equation modelling techniques in conjunction with multi-group analysis. Most of the hypothesized moderating effects of national cultural factors were found to be statistically significant. Our findings suggest that cultural factors should be considered in order to design effective information security policies, practices and technologies in global networks where multiple cultures coexist. Theoretical and practical implications of the study are discussed.     

Query generation for retrieving data from distributed semistructured documents using a metadata interface

We describe a method for generating queries for retrieving data from distributed heterogeneous semistructured documents, and its implementation in the metadata interface DDXMI (distributed document XML metadata interchange). The proposed system generates local queries appropriate to local schemas from a user query over the global schema. The system constructs mappings between global schema and local schemas (extracted from local documents if not given), path substitution, and node identification for resolving the heterogeneity among nodes with the same label that often exist in semistructured data. The system uses Quilt as its XML query language. An experiment is reported over three local semistructured documents: ‘thesis’, ‘reports’, and ‘journal’ documents with ‘article’ global schema. The prototype was developed under Windows system with Java and JavaCC.     

Vibration suppression of a flexible robot manipulator with a lightweight piezo-composite actuator

The increasing demand for high-speed performance and low energy consumption has necessitated the design of lightweight mechanical systems. The active vibration suppression of a flexible manipulator is important in many engineering applications, such as robot manipulators and high-speed flexible mechanisms, because the flexibility of lightweight manipulators induces a vibration problem. Frequently, the optimal parameters determined for a certain control algorithm might not cover a wide range of operating conditions. Hence, we have proposed and developed a lookup table control method for a flexible manipulator that can tune itself to optimal parameters on the basis of the initial maximum responses of the controlled system and a genetic algorithm. The genetic algorithm is used to search for optimal parameters with regard to positive position feedback and thereby minimizes the objective functions determined from the initial maximum responses. Our lookup table, which has the optimal parameters of the positive position feedback as a function of the initial maximum responses, can be used in a real-time control algorithm. Recommended by Editorial Board member Hyoukryeol Choi under the direction of Editor Jae-Bok Song. This work was supported by the Korea Research Foundation under grant KRF 2006-005-J03302 and the Korea Science and Engineering Foundation under grant KOSEF R0A-2007-000-20012-0. Van Phuoc Phan received the BS (2006) from the Department of Aeronautical Engineering, HCM University of Technology, Vietnam. Currently, he is a Master student at the Department of Advanced Technology Fusion, Konkuk University in Seoul, Korea. His interests are structural dynamics of small systems, smart structure and material, and finite element analysis. Nam Seo Goo graduated from the Department of Aeronautics Engineering of Seoul National University with honors in 1990, and got master and Ph.D. degrees in Department of Aerospace Engineering at the same university in 1992 and 1996, respectively. His Ph.D. degree was on the structural dynamics of aerospace systems. As soon as he got a Ph.D. degree, he entered the agency for defense development as a Senior Researcher. After four years’ service, he joined Department of Aerospace Engineering in Konkuk University, Seoul, Korea in 2002, currently serving an Associate Professor of Department of Advanced Technology Fusion. His current research interests are structural dynamics of small systems, smart structure and material, and MEMS applications. Hoon Cheol Park received his BS (1985) and MS(1987) degrees from Seoul National University in Seoul, Korea and Ph.D.(1994) degree from the University of Maryland at College Park, MD, USA. He joined the Department of Aerospace Engineering, Konkuk University in Seoul, Korea in 1995, and he is currently a Professor in the Department of Advanced Technology Fusion. His professional experience includes Kia Motors (1986–1988) and Korea Aerospace Research Institute (1994–1995). His specialty is the finite element analysis and recent research topic is mainly biomimetics.     

New approaches to process simplification for large‐area high‐resolution TFT‐LCDs

Abstract— Novel process architectures are proposed for fabricating large‐area high‐resolution TFT‐LCDs with a minimal number of process steps. A low contact resistance between Al bus lines and the transparent conductive oxide layer, necessary for large‐area panels, is obtained by inducing a self‐formed inter‐metallic compound layer at the interface without using any additional buffer or capping layers. For enhanced brightness and resolution, a new TFT array structure integrated on a color‐filter substrate, referred to as an Array on Color Filter (AOC) structure, has been developed. Good‐quality TFTs were successfully constructed on the newly developed color filter for AOC within a sufficiently wide process margin. By adopting these novel technologies, a 15.0‐in. XGA prototype panel was fabricated and shows good display performance. Thus, these novel technologies have improved cost efficiency and productivity for TFT‐LCD manufacturing, and can be applied to the development of TFT‐LCDs of extended display area and enhanced resolution, benefiting from the low resistance bus lines, the high aperture ratio, and reduction in total process steps.     

Parameter optimization of an on-chip voltage reference circuitusing evolutionary programming

This paper presents an application of evolutionary programming to parameter optimization in the design of a voltage reference circuit. Designing circuits consists of two steps: topological design and parameter determination. After designing a topology suitable for the circuit, the designer selects an appropriate value for each circuit element from a circuit analysis and his experience. This step is difficult and time consuming because the designer must consider many factors simultaneously. As more precise circuits are required, parameter optimization becomes more complex. The voltage reference circuit, which requires a precise reference voltage independent of power fluctuation and temperature change, is such an example. In this paper, evolutionary programming is used as an effective method of finding good parameter values for the elements of the voltage reference circuit. Simulation results show that this method provides good performance and can be used as an effective method for circuit design     

Structural and optical properties of microcrystalline silicon films deposited by plasma enhanced chemical vapour deposition

Hydrogenated microcrystalline (c) silicon films were prepared by plasma enhanced chemical vapour deposition using an Ar-diluted SiH₄ gas at various deposition conditions. The substrate temperature and RF power were varied from 150 to 400 C and from 10 to 120 W, respectively. Structure and microstructure were examined by X-ray diffraction, Raman spectroscopy, and scanning electron microscopy. Hydrogen bonding and optical properties were investigated by FTIR spectra and UV transmission spectra. The crystal fraction of the films increased as the deposition temperature decreased and RF power increased. More definite columnar morphology was developed with increasing crystal fraction. The existence of c-Si above a critical RF power (>30 W) suggests that SiH₂ radical in plasma plays an important role for the formation of columnar morphology and c-Si. IR absorption analysis showed that the SiH₂/SiH bonding ratio in the silicon films increased as the crystal fraction increased. The UV absorption coefficient of the films became smaller as the deposition temperature and RF power increased.     

Hierarchical Integrated Hybrid Structural Electrodes Based on Co-N/C and Mo-doped NiCo-LDH@Co-N/C Anchored on MX/CF for High Energy Density Fiber-Shaped Supercapacitor

The judicious design of highly electrochemically active materials on 1D fiber substrate to form a hierarchical integrated hybrid structure is an efficient technique to improve the limited cylindrical space and volumetric energy density of fiber-shaped supercapacitors (FSCs). Herein, a 3D negative electrode, consisting of vertically aligned interconnected mesoporous Co-N/C leaf-like structure on 1D MXene-carbon fiber (Co-N/C@MX/CF) is prepared by controlling the composition and morphology. At the same time, a 3D positive electrode is also prepared by introducing Mo in NiCo-LDH anchored on Co-N/C@MX/CF (Mo-NiCo-LDH@Co-N/C@MX/CF) by electrodeposition method. Benefitting from the systematic hierarchical structures with highly accessible surface area, adequate pore size and easy permeation of electrolyte, both positive and negative electrodes demonstrate highly improved electrochemical performance with areal capacity/capacitance of 0.96 mAh cm⁻²/4.55 mF cm⁻² at a current density of 3.86 mA cm⁻², respectively. Furthermore, the fiber-shaped solid-state hybrid supercapacitor (FSHSC) based on Mo_1.5NiCo-LDH@Co-N/C@MX/CF(+)//Co-N/C_0.5@MX/CF(−) is fabricated, exhibiting compelling energy density of 86.72 mWh cm⁻³ at a power density of 480.30 mW cm⁻³ with an outstanding capacitance retention of 80.2% after 20000 galvanostatic-charge-discharge cycles. This study puts forward a new perspective on the development of highly efficient FSCs for practical application.     

Dense Platinum/Nickel Oxide Heterointerfaces with Abundant Oxygen Vacancies Enable Ampere-Level Current Density Ultrastable Hydrogen Evolution in Alkaline

Platinum (Pt) remains the benchmark electrocatalyst for alkaline hydrogen evolution reaction (HER), but its industry-scale hydrogen production is severely hampered by the lack of well-designed durable Pt-based materials that can operate at ampere-level current densities. Herein, based on the original oxide layer and parallel convex structure on the surface of nickel foam (NF), a 3D quasi-parallel architecture consisting of dense Pt nanoparticles (NPs) immobilized oxygen vacancy-rich NiO_x heterojunctions (Pt/NiO_x-O_V) as an alkaline HER catalyst is developed. A combined experimental and theoretical studies manifest that anchoring Pt NPs on NiO_x-O_V leads to electron-rich Pt species with altered density of states (DOS) distribution, which can efficiently optimize the d-band center and the adsorption of reaction intermediates as well as enhance the water dissociation ability. The as-prepared catalyst exhibits extraordinary HER performance with a low overpotential of 19.4 mV at 10 mA cm⁻², a mass activity 16.3-fold higher than that of 20% Pt/C, and a long durability of more than 100 h at 1000 mA cm⁻². Furthermore, the assembled alkaline electrolyzer combined with NiFe-layered double hydroxide requires extremely low voltage of 1.776 V to attain 1000 mA cm⁻², and can operate stably for more than 400 h, which is rarely achieved.     

Genetic-Chicken Swarm Algorithm for Minimizing Energy in Wireless Sensor Network

Wireless Sensor Network (WSN) technology is the real-time application that is growing rapidly as the result of smart environments. Battery power is one of the most significant resources in WSN. For enhancing a power factor, the clustering techniques are used. During the forward of data in WSN, more power is consumed. In the existing system, it works with Load Balanced Clustering Method (LBCM) and provides the lifespan of the network with scalability and reliability. In the existing system, it does not deal with end-to-end delay and delivery of packets. For overcoming these issues in WSN, the proposed Genetic Algorithm based on Chicken Swarm Optimization (GA-CSO) with Load Balanced Clustering Method (LBCM) is used. Genetic Algorithm generates chromosomes in an arbitrary method then the chromosomes values are calculated using Fitness Function. Chicken Swarm Optimization (CSO) helps to solve the complex optimization problems. Also, it consists of chickens, hens, and rooster. It divides the chicken into clusters. Load Balanced Clustering Method (LBCM) maintains the energy during communication among the sensor nodes and also it balances the load in the gateways. The proposed GA-CSO with LBCM improves the lifespan of the network. Moreover, it minimizes the energy consumption and also balances the load over the network. The proposed method outperforms by using the following metrics such as energy efficiency, ratio of packet delivery, throughput of the network, lifetime of the sensor nodes. Therefore, the evaluation result shows the energy efficiency that has achieved 83.56% and the delivery ratio of the packet has reached 99.12%. Also, it has attained linear standard deviation and reduced the end-to-end delay as 97.32 ms.