• Journal of Power Electronics
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• 제18권3호
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• pp.746-756
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• 2018

Harmonic resonance exists in grid-connected inverter systems. In order to determine the network components that contribute to harmonic resonance and the composition of the resonant circuit, sensitivity theory is applied to the resonance characteristic analysis. Based on the modal analysis, the theory of sensitivity is applied to derive a formula for determining the sensitivities of each network component parameter under a resonance circumstance that reflects the participation of the network component. The solving formula is derived for both parallel harmonic resonance and series harmonic resonance. This formula is adopted to a 4-node grid-connected test system. The analysis results reveal that for a certain frequency, the participation of parallel resonance and series resonance are not the same. Finally, experimental results demonstrate that the solving formula for sensitivity is feasible for grid-connected systems.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권3호
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• pp.576-599
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• 2013

Protocol reverse engineering is useful for many security applications, including intelligent fuzzing, intrusion detection and fingerprint generation. Since manual reverse engineering is a time-consuming and tedious process, a number of automatic techniques have been proposed. However, the accuracy of these techniques is limited due to the complexity of binary instructions, and the derived formats have missed constraints that are critical for security applications. In this paper, we propose a new approach for protocol format extraction. Our approach reasons about only the evaluation behavior of a program on the input message from concolic execution, and enables field identification and constraint inference with high accuracy. Moreover, it performs binary analysis with low complexity by reducing modern instruction sets to BIL, a small, well-specified and architecture-independent language. We have implemented our approach into a system called Icefex and evaluated it over real-world implementations of DNS, eDonkey, FTP, HTTP and McAfee ePO protocols. Experimental results show that our approach is more accurate and effective at extracting protocol formats than other approaches.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2007년도 정기 학술대회 논문집
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• pp.361-366
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• 2007

This study reflects on the subjects of tile papers published by Journal of Automation in Construction, which has focused on such fusion-technology research areas in civil engineering as robotics and automation and observed a growing number of papers and extensiveness of participation during the 2000-2006 periods. This paper provides a current perspective on technology-fusion research in civil engineering, as reflected in the journal of Automation in Construction. Journal of Automation in Construction (AIC) is intended to be of interest of industry personnel, government personnel and researcher in Information Technology (IT) and Automation research in civil engineering. This paper is intended to show a cross country comparison of technology-fusion research through analysis of papers. The research results show that there is a need to increase research collaboration between industry and academia, government and academia, and industry and government to advance the construction industry.

• Journal of Power Electronics
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• 제16권1호
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• pp.319-328
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• 2016

In this study, we first briefly introduce the effect of circulating current control on the modulation signal of a modular multilevel converter (MMC). The maximum modulation index is also theoretically derived. According to the optimal modulation index analysis and the model in the continuous domain, different DC-side output impedance equivalent models of MMC with/without compensating component are derived. The DC-side impedance of MMC inverter station can be regarded as a series xR + yL + zC branch in both cases. The compensating component of the maximum modulation index is also related to the DC equivalent impedance with circulating current control. The frequency characteristic of impedance for MMC, which is observed from its DC side, is analyzed. Finally, this study investigates the prediction of the DC voltage ripple transfer between two-terminal MMC high-voltage direct current systems under unbalanced conditions. The rationality and accuracy of the impedance model are verified through MATLAB/Simulink simulations and experimental results.

• Journal of Power Electronics
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• 제18권1호
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• pp.185-194
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• 2018

Interaction among multiple grid-connected inverters has a negative impact on the stable operations and power quality of a power grid. The interrelated influences of inverter inductor-capacitor-inductor filters constitute a high-order power network, and consequently, excite complex resonances at various frequencies. This study first establishes a micro-grid admittance matrix, in which inverters use deadbeat control. Multiple resonances can then be evaluated via modal analysis. For the active damping method applied to deadbeat control, the sampling frequency and the stable domain of the virtual damping ratio are also presented by analyzing system stability in the discrete domain. Simulation and experimental results confirm the efficiency of modal analysis and stable domain calculation in multi-inverter grid-connected systems.

• Current Optics and Photonics
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• 제2권6호
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• pp.576-581
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• 2018

A new approach for identification of a microwave frequency using an integrated optical waveguide chip, combined with a phase modulator (PM) and two microring resonators (MRRs), is proposed, theoretically deduced, and verified. By wavelength tuning to set the PM under the condition of a double side band (DSB), the measurement range can be started from the dc component, and the measurement range and response slope can be adjusted by designing the radius and transmission coefficient of the MRR. Simulations reveal that the amplitude comparison function (ACF) has a monotonic relationship from dc to 32.5 GHz, with a response slope of 5.15 dB under conditions of DSB modulation, when the radius values, transmission coefficients, and the loss factors are designed respectively as $R_1=400{\mu}m$, $R_2=600{\mu}m$, $t_1=t_2=0.63$, and ${\gamma}_1={\gamma}_2=0.66$. Theoretical calculations and simulation results both indicate that this new approach has the potential to be used for measuring microwave frequencies, with the advantages of compact structure and superior reconfigurability.

• 산업경영시스템학회지
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• 제38권4호
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• pp.202-211
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• 2015

Companies build the factory automation system to improve management effectiveness and productivity as prime strategies for sustainable growth. But most companies undergo various trials and errors while carrying out the project without elaborate preparation stage for factory automation. In this study, we tried to verify what factors are critical to effectively building distribution automation system, which is a branch of factory automation system. A consulting model for setting up a Material Handling Automation System by utilizing the Stage-Gate Process, which is product development process was studied. 29 material handling automation projects carried out between the year 1990 to 2013 at K-Company were selected. Interviews with the project managers, operators and maintenance personnels, various records and current status of the projects were used as data for structural equations based on the Milan consulting model and existing researches of factory automation, CIM for material handling automation. Creating effective basis of production, material handling system and energy saving system with expert review, when preparing a material handling automation project, help promote the project planning thus contributing to the performance of the resulting system, which appears though rather weakly in our data. Also the effect of material handling automation can be enhanced through sufficient and effective links to the relevant environments such as production logistics management and automated warehouses. More detailed planning characteristics of project promotion or some time-series data of effective Material Handling Automation System could enhace furthur studies. We propose a consulting model for setting up an efficient material handling automation system.

• 융합정보논문지
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• 제9권7호
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• pp.8-13
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• 2019

최근 4차 산업혁명 시대 흐름에 발맞추어 인공지능을 이용한 자동화 기술을 다양한 산업현장에 적용하는 사례가 증가하고 있다. 특히, 정부의 주 52시간 근무제 도입으로 기업들은 인력 운영의 어려움이 가중되고 있어, 효율적인 인력 운영을 위해 사무환경 자동화를 위한 RPA(Robotic Process Automation)에 관심을 두고 은행, 보험, 카드사 등에서 Back-Office 업무 위주로 도입하고 있다. 이러한 RPA 솔루션은 인공지능 기반 인식기술, Script 작성 기술, 업무 소프트웨어와 API(Application Process Interface) 연계 기술 등이 요구되며, Automate One, Automation Anywhere, UiPath, Blue Prism 등과 같은 다양한 솔루션들이 제공되고 있다. 본 논문에서는 기에 수작업으로 수행하던 업무를 대신할 수 있는 RPA 솔루션의 요소 기술, 시장 동향, RPA 도입 효율성에 대해 분석하고 이를 서술하였다.

• International Journal of Control, Automation, and Systems
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• 제5권2호
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• pp.128-137
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• 2007

A robust adaptive controller design for a class of Markovian jump parametric -strict-feedback systems is given. The disturbances considered herein include both uncertain nonlinearities and Wiener noises of unknown covariance. And they satisfy some bound-conditions. By using stochastic Lyapunov method in Markovian jump systems, a switching robust adaptive controller was obtained that guarantees global uniform ultimate boundedness of the closed-loop jump system.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2004년도 전력전자학술대회 논문집(1)
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• pp.435-438
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• 2004

Lately, the Intelligent Electronic Device(ED) and the Power System Automation make subjects of discussions and studies. The IED uses microprocessors to practice a lot of functions. In the analog time, an equipment practices only one or two functions. But according to the development of microprocessor and digital technology, it can be implemented by using those kinds of state of the art technology and its function is become more and more powerful. Also, the proliferation of IED makes possible to construct power system automation. An automation of power system make more convenient, safe, and accurate power system. In this paper, a digital protective relay which is a kind of IED and the power automation system are briefly discussed with development and application cases.