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A Systematic Mapping Review of Usability Evaluation Methods for Software Development Process
Freddy Paz,José Antonio Pow-Sang 보안공학연구지원센터(IJSEIA) 2016 International Journal of Software Engineering and Vol.10 No.1
Given that usability is one of the most important aspects of software quality, several methods have been developed in order to establish techniques capable of evaluating this attribute from early phases of the software development process. However, the choice of the most appropriate method for a particular scenario is still a difficult decision, due to the existence of a vast number of approaches that are described in the literature for this purpose. Therefore, a systematic mapping review was conducted in order to identify the most commonly used usability evaluation techniques in software developments. A total of 1169 studies were identified, of which only 215 studies were selected for this review. According to the analysis, most cases studies establish the use of usability questionnaires as assessment tool. In addition, health informatics and Web applications are the software domain and type of application that are frequently reported in these evaluations. This work has allowed to reach promising results in this area. It is intended to be a guide for specialists to support the choice of the most suitable method for a particular scenario.
Design of Mesoporous Silica at Low Acid Concentrations in Triblock Copolymer-Butanol-Water Systems
Freddy Kleitz,유룡,Tae-Wan Kim 대한화학회 2005 Bulletin of the Korean Chemical Society Vol.26 No.11
Assembly of hybrid mesophases through the combination of amphiphilic block copolymers, acting as structure-directing agents, and silicon sources using low acid catalyst concentration regimes is a versatile strategy to produce large quantities of high-quality ordered large-pore mesoporous silicas in a very reproducible manner. Controlling structural and textural properties is proven to be straightforward at low HCl concentrations with the adjustment of synthesis gel composition and the option of adding co-structure-directing molecules. In this account, we illustrate how various types of large-pore mesoporous silica can easily be prepared in high phase purity with tailored pore dimensions and tailored level of framework interconnectivity. Silica mesophases with two-dimensional hexagonal (p6mm) and three-dimensional cubic (Fm m, Im m and Ia d) symmetries are generated in aqueous solution by employing HCl concentrations in the range of 0.10.5 M and polyalkylene oxide-based triblock copolymers such as Pluronic P123 (EO20-PO70-EO20) and Pluronic F127 (EO106-PO70-EO106). Characterizations by powder X-ray diffraction, nitrogen physisorption, and transmission electron microscopy show that the mesoporous materials all possess high specific surface areas, high pore volumes and readily tunable pore diameters in narrow distribution of sizes ranging from 4 to 12 nm. Furthermore, we discuss our recent advances achieved in order to extend widely the phase domains in which single mesostructures are formed. Emphasis is put on the first synthetic product phase diagrams obtained in SiO2-triblock copolymer-BuOH-H2O systems, with tuning amounts of butanol and silica source correspondingly. It is expected that the extended phase domains will allow designed synthesis of mesoporous silicas with targeted characteristics, offering vast prospects for future applications.
Freddy, Tan Kheng Suan,Lee, June-Hee,Moon, Hyun-Cheol,Lee, Kyo-Beum,Rahim, Nasrudin Abd Institute of Electrical and Electronics Engineers 2017 IEEE transactions on industrial electronics Vol.64 No.9
<P>This paper underpins the principles for generating reactive power in single-phase transformerless photovoltaic (PV) inverters. Two mainstream and widely adopted PV inverters are explored, i.e., H5 and HERIC. With conventional modulation techniques, reactive power cannot be realized in H5 and HERIC due to the absence of freewheeling path in negative power region. Based on the study, modulation techniques are proposed to provide bidirectional current path during freewheeling period. With proposed modulation technique, reactive power control is achieved in H5 and HERIC inverters, without any modification on the converter structures. The performances of the proposed modulation techniques are studied via MATLAB simulation and further validated with experimental results.</P>
Structure and electrochemical properties of CNT-supported Li-Ti-O anode material for Li-ion battery
Freddy Baltazar Iniguez,정희민,Ahmed Yousef Mohamed,말도나도노잘레스폴,최환준,정순기,JONG BAE PARK,김양수,조덕용 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.112 No.-
We investigated the structural and electrochemical properties of Li-Ti-O (LTO) and carbon nanotube(CNT)-added LTO for anode material in secondary Li-ion batteries using various techniques. The studyfocused on elucidating the effects of the microstructural evolution in LTO and the CNT addition on batteryfunctionality. For all the tested compositions of LTO ([Li]/[Ti] = 0.9, 1.0 and 1.22), the system is fully oxidizedto comprise a mixed-phase having Li4+2dTi5O12+d (d’s are approximately 0.14, 0.25, and 0.65, respectively)and Li2TiO3 structures. The results of the half-cell tests show a decrease in charge/dischargecapacity with increasing [Li]/[Ti] ratio, and the detailed structural and chemical analyses unequivocallyreveal that the such degradation in the electrochemical property originates mainly from the increaseof Li content (d). Meanwhile, after adding CNT, the Li capacity becomes greatly increased while theLTO composition and the redox kinetics do not change significantly. The origin of the improved specificcapacity is associated with the formation of micron-sized structures at the surface of the LTO particles. Thereby we demonstrate that surface engineering via the CNT addition is a promising way to improvethe performance of the LTO-based anode material.
Freddy Boscán,María J. Barandiaran,Maria Paulis 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.58 No.-
Miniemulsion preparation by low-energy phase inversion temperature (PIT) was performed for laurylmethacrylate (LMA) using polyethoxylated non-ionic emulsifiers. The minimum emulsifier content(4.5 wt%) and maximum amount of monomer (33 wt%) that led to stable miniemulsions was optimizedand the corresponding miniemulsions polymerized. Depending on the polymerization temperature, aconventional miniemulsion polymerization or a nanoemulsion polymerization (NEP) mechanism werefollowed. The possible explanation for the change of the reaction mechanism has been presented. Moreover, the robustness of the PIT technique for industrial applications was confirmed by polymerizinga LMA/isobornyl acrylate superhydrophobic monomer mixture.
Design of Mesoporous Silica at Low Acid Concentrations in Triblock Copolymer-Butanol-Water Systems
Kleitz, Freddy,Kim, Tae-Wan,Ryoo, Ryong Korean Chemical Society 2005 Bulletin of the Korean Chemical Society Vol.26 No.11
Assembly of hybrid mesophases through the combination of amphiphilic block copolymers, acting as structuredirecting agents, and silicon sources using low acid catalyst concentration regimes is a versatile strategy to produce large quantities of high-quality ordered large-pore mesoporous silicas in a very reproducible manner. Controlling structural and textural properties is proven to be straightforward at low HCl concentrations with the adjustment of synthesis gel composition and the option of adding co-structure-directing molecules. In this account, we illustrate how various types of large-pore mesoporous silica can easily be prepared in high phase purity with tailored pore dimensions and tailored level of framework interconnectivity. Silica mesophases with two-dimensional hexagonal (p6mm) and three-dimensional cubi (Fm$\overline{3}$m, Im$\overline{3}$m and Ia$\overline{3}$d) symmetries are generated in aqueous solution by employing HCl concentrations in the range of 0.1−0.5 M and polyalkylene oxide-based triblock copolymers such as Pluronic P123 $(EO_{20}-PO_{70}-EO_{20})$ and Pluronic F127 $(EO_{106}-PO_{70}-EO_{106})$. Characterizations by powder X-ray diffraction, nitrogen physisorption, and transmission electron microscopy show that the mesoporous materials all possess high specific surface areas, high pore volumes and readily tunable pore diameters in narrow distribution of sizes ranging from 4 to 12 nm. Furthermore, we discuss our recent advances achieved in order to extend widely the phase domains in which single mesostructures are formed. Emphasis is put on the first synthetic product phase diagrams obtained in $SiO_2$-triblock copolymer-BuOH-$H_2O$ systems, with tuning amounts of butanol and silica source correspondingly. It is expected that the extended phase domains will allow designed synthesis of mesoporous silicas with targeted characteristics, offering vast prospects for future applications.