• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.9
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• pp.2529-2549
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• 2023

For effectively lowering down the risk of cyber threating, the zero-trust architecture (ZTA) has been gradually deployed to the fields of smart city, Internet of Things, and cloud computing. The main concept of ZTA is to maintain a distrustful attitude towards all devices, identities, and communication requests, which only offering the minimum access and validity. Unfortunately, adopting the most secure and complex multifactor authentication has brought enterprise and employee a troublesome and unfriendly burden. Thus, authors aim to incorporate machine learning technology to build an employee behavior analysis ZTA. The new framework is characterized by the ability of adjusting the difficulty of identity verification through the user behavioral patterns and the risk degree of the resource. In particular, three key factors, including one-time password, face feature, and authorization code, have been applied to design the adaptive multifactor continuous authentication system. Simulations have demonstrated that the new work can eliminate the necessity of maintaining a heavy authentication and ensure an employee-friendly experience.

• International Journal of Highway Engineering
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• v.7 no.3 s.25
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• pp.79-91
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• 2005

The temperature patterns in Portland cement concrete (PCC) pavements were measured and comprehensively analyzed from the beginning of the concrete placement based on the temperature measurement technique developed using innovative and inexpensive temperature measurement sensors. The temperature measurements in PCC pavements were taken at several different locations forvarious slab thicknesses. The concrete temperature patterns in the vertical and longitudinal directions of the pavement were analyzed and the effects of the pavement surface reflectivity, shading, and covering on the concrete temperatures were evaluated. The results of this study showed that the significant differences in the maximum concrete temperatures on the placement day were observed according to the concrete placement time. Since the zero-stress temperature is a function of the maximum concrete temperature on the placement day, the placement time would be an important factor that affects the behavior and performance of concrete pavements. The surface conditions of the pavement, such as the surface color, shading, and covering also affected the temperature patterns in PCC pavements significantly.

• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.4
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• pp.279-285
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• 2020

An open-end winding (OEW) permanent magnet synchronous motor with dual inverters can synthesize large voltages for a motor with the same DC link voltage. This ability has the advantage of reducing the use of DC/DC boost converters or high voltage batteries. However, zero-sequence voltage (ZSV), which is caused by the difference in the combined voltage between the primary and secondary inverters, can generate a zero-sequence current (ZSC) that increases system losses. Among the methods for eliminating this phenomenon, combining voltage vector eliminated ZSV cannot be accomplished by the conventional Pulse Width Modulation(PWM) method. In this study, a PWM carrier generation method using functionalization to generate a switching pattern to suppress ZSC is proposed and applied to analyze the control influence of the center-zero vector in the switching sequence about the current ripple.

• Journal of the Korean Chemical Society
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• v.56 no.4
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• pp.484-490
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• 2012

The tin (IV) oxide nanoparticles are prepared by controlled precipitation method and calcined at temperatures of $200-600^{\circ}C$. The prepared $SnO_2$ nanoparticles characterized by XRD patterns, TEM image, IR and UV-Vis spectra. The XRD patterns and TEM image show the tetragonal structure and spherical morphology for $SnO_2$ nanoparticles, respectively. The photocatalytic activity of the prepared $SnO_2$ nanoparticles studied in degradation reaction of methylene blue (MB). The results show the size of nanoparticles, band-gap energy and photocatalytic activity of $SnO_2$ depends on the calcinations temperature. The $SnO_2$ nanoparticles calcined at $500^{\circ}C$ indicated the highest photoreactivity. Also, the zero-valent tin (ZVT) nanoparticles with tetragonal structure are prepared by a reducing agent and used as a catalyst in degradation of MB. In basic pH of 11, the degradation >95% of MB at time 150 min obtained at presence of ZVT nanoparticles.

• Journal of international Conference on Electrical Machines and Systems
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• v.1 no.4
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• pp.448-456
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• 2012

This paper presents a multilevel inverter configuration which is designed by insertion of a bidirectional switch between capacitive voltage sources and a conventional H-bridge module. The modified inverter can produce a better sinusoidal waveform by increasing the number of output voltage levels. By serial connection of two modified H-bridge modules, it is possible to produce 9 output voltage levels including zero. There are 24 basic switching patterns with the 9 output voltage levels. Among the patterns, we select the 2 most efficient switching patterns to get a lower switching loss and minimum dv/dt stress. We then analyze characteristics of Total Harmonic Distortion (THD) of the output voltage with variation of input voltage by computer-aided simulations and experiments.

• English Language & Literature Teaching
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• v.13 no.4
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• pp.109-126
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• 2007

English article has been considered as one of the most difficult areas to learn among ESL/EFL students. The current paper reviews English learners' article error patterns as well as pedagogy in order to teach English articles and to minimize learning difficulties on English articles. Different pedagogy for English articles on the basis of learners' proficiency levels are suggested as each proficiency level student shows a different error tendency; beginning level language learners used the zero article with the most facility while intermediate level language learners used the definite article the most accurately. However, studies about high advanced level learners' error patterns present that these high accuracy rates among beginning level students might be a result of students' plain guessing. Considering these error patterns, pedagogy for advanced level is also suggested.

• Proceedings of the KOSOMBE Conference
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• v.1996 no.05
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• pp.6-9
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• 1996

In this paper, we attempted to analyze the contraction patterns of elbow flexor muscle during isometric, concentric and eccentric contraction. The analysis parameters are consisted of Sequency domain parameters (mean frequency, median frequency, skewness, kurtosis) and time domain parameters (zero crossing, positive maxima, integrated EMG). As a results, the analysis parameters have specific trends for muscles, muscle contraction patterns, muscle contraction angles. Especially, at the time domain analysis, IEMG is a dominant parameter for analysis of activation patterns, and the skewness, kurtosis are useful parameters for functional recognition.

• Journal of Power Electronics
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• v.16 no.4
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• pp.1469-1482
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• 2016

In hybrid energy storage systems, supercapacitors are usually connected in series to meet the required voltage levels. Equalizers are effective in prolonging the life of hybrid energy storage systems because they eliminate the voltage imbalance on cells. This study proposes a modularized equalizer, which is based on a combination of a half-bridge inverter, an inductor, and two auxiliary capacitors. The proposed equalizer inherits the advantages of inductor-based equalization systems, but it also offers unique merits, such as low switching losses and an easy-to-use control algorithm. The zero-voltage switching scheme is analyzed, and the power model is established. A fixed-frequency operation strategy is proposed to simplify the control and lower the cost. The switching patterns and conditions for zero-voltage switching are discussed. Simulation results based on PSIM are presented to verify the validity of the proposed equalizer. An equalization test for two supercapacitor cells is performed. An experimental hybrid energy storage system, which consists of batteries and supercapacitors, is established to verify the performance of the proposed equalizer. The analysis, simulation results, and experimental results are in good agreement, thus indicating that the circuit is practical.

• 한국태양에너지학회:학술대회논문집
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• 2009.04a
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• pp.121-126
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• 2009

This study analyzed the standard school's energy usage and patterns as the zero-energy goal of primary school building, and proposed the energy reduction process of school building using energy analysis computing simulation tool. As a analysis simulation tool, Visual DOE 4.0 is used. For analysis of actual energy usage, selected primary school that is standard in the nation's energy consumption. Standard of the school's energy consumption analysis were devided into electric and gas energy. Input parameters of the simulation program based on the literature material and field survey material. after, but it was calibrated to comparison with the standard school's energy consumption. Finally, its energy usage analyzed by component and made the priority order of energy saving. Applied energy saving technologies are envelopment insulation, high efficiency lighting, high performance HAVC system and used active equipment system of solar collector and photovoltaic generation for additional savings.

• Journal of Pharmaceutical Investigation
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• v.19 no.4
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• pp.179-183
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• 1989

Drug release experiments were performed based on pH-sensitive swelling behaviors of polymethacrylic acid. 5-Fluorouracil as a nonionic model drug revealed release patterns depending solely on pH-dependent swelling kinetics of polymethacrylic acid. In contrast, release of propranolol hydrochloride as a cationic model drug was significantly affected by ionic drug-polymer interaction as well as the swelling kinetics. Accordingly, a zero-order release pattern was obtained at pH 7, which was distinguished from the general matrix type drug release pattern.