• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.313-316
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• 2002

In this paper, we present an online scheme for parameter estimation of solar cell, based on the model adjustment technique and a genetic algorithm. The ideal diode model and the diode model with series and shunt resistor are used to estimate their parameters. Simulation works using field data in the form of a VI characteristic curve are carried out to demonstrate the effectiveness of the proposed method.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2014년도 전력전자학술대회 논문집
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• pp.542-543
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• 2014

In this paper, an estimation scheme based on an augmented sigma-point Kalman filter to estimate the state of charge (SOC) of the battery is presented, where the battery parameters of the series resistance ($R_o$), diffusion capacitance ($C_1$) and resistance ($R_1$) are also estimated through the recursive least squares (RLS) for better accuracy of the SOC. The effectiveness of the proposed method is verified by simulation results.

• 한국지능시스템학회논문지
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• 제8권3호
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• pp.80-87
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• 1998

This paper presents and online scheme for fuzzy modelling of nonlinear systems, based on the model adjustment technique and the genetic algorithm technique. The fuzzy model is characterized by fuzzy "if-then" rules which represent locally linear input-output relations whose consequence parts are defined as subsystems of a nonlinear sysem. The discrete-time model for each subsystem is obtained to deal with initalization and unmeasurable signal problems in online estimation and the final output of the fuzzy model is computed from the outputs of the discrete-time models. Then, the parameters of both the premise and consequence parts of the fuzzy model are adjusted by a genetic algorithm. A set of simulation works is carried out to demonstrate the effectiveness of the proposed method.ed method.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2007년도 하계학술대회 논문집
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• pp.391-393
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• 2007

The rotor speed and flux information is most important in the vector control. The accuracy of flux observers for induction machine inherently depends on parameter sensitivity. The control strategy is using online flux observer for flux estimation. In the proposed system, the speed control characteristics using a online flux observer control isn't affected by a load torque parameter disturbance. Simulation results are presented to prove the effectiveness of the adaptive sliding mode controller for the drive variable load of induction motor.

• Journal of Power Electronics
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• 제16권5호
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• pp.1752-1762
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• 2016

To achieve higher reliability in the modular multilevel converters (MMC) for HVDC transmission systems, the internal condition of the DC capacitors of the submodules (SM) needs to be monitored regularly. For an online estimation of the SM capacitance, a controlled AC current with double the fundamental frequency is injected into the circulating current loop of the MMC, which results in current and voltage ripples in the SM capacitors. The capacitor currents are calculated from the arm currents and their switching states. By processing these AC voltage and current components with digital filters, their capacitances are estimated by a recursive least square (RLS) algorithm. The validity of the proposed scheme has been verified by simulation results for a 300-MW, 300-kV HVDC system. In addition, its feasibility has been verified by experimental results obtained with a reduced-scale prototype. It has been shown that the estimation errors for both the simulation and experimental tests are 1.32% at maximum.

• 한국지반환경공학회 논문집
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• 제7권1호
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• pp.67-80
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• 2006

본 논문에서는 지반 하이브리드-온라인 시뮬레이션의 방법을 압밀 해석에 적용하기 위한 시도를 수행하였다. 일반적인 수치해석법이 실내시험을 통해 얻어진 흙의 구성모델을 이상화시켜 사용하는 것과 달리, 이 방법에서는 흙의 거동을 요소시험체로부터 직접 도입해가면서 해석을 수행한다. 그러므로 복잡한 파라미터의 평가과정이 생략될 수 있게 되며 인위적 이상화에 의한 해석 오차를 경감할 수 있게 된다. 본 논문에서는 실험장치의 물리적 성능을 검증하기 위하여 단계압밀시험과 투수시험(CONPERM test)을 수행하여 제어와 계측의 결과를 고찰하였으며, 시스템으로부터 얻은 데이터의 건전성을 평가하기 위하여 검증해석을 수행하였다. 결과적으로, 본 연구를 통해 개발된 하이브리드-온라인 압밀해석 시스템은 재성형된 카오리나이트의 압밀거동을 모순없이 재현하고 있음을 알 수 있었다.

• Journal of Power Electronics
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• 제16권5호
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• pp.1981-1989
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• 2016

Battery diagnosis is vital to battery-based applications because it ensures system reliability by avoiding battery failure. This paper presents a novel intelligent battery charger with an online diagnosis function to circumvent interruptions in system operation. The charger operates in normal charging and diagnosing modes. The diagnosis function is performed with the impedance spectroscopy technique, which is achieved by injecting a sinusoidal voltage excitation signal to the battery terminals without the need for additional hardware. The impedance spectrum of the battery is calculated based on voltage excitation and current response with the aid of an embedded digital lock in amplifier in a digital signal processor. The measured impedance data are utilized in the application of the complex nonlinear least squares method to extract the battery parameters of the equivalent circuit. These parameters are then compared with the reference values to reach a diagnosis. A prototype of the proposed charger is applied to four valve-regulated lead-acid batteries to measure AC impedance. The results are discussed.

• International Journal of Computer Science & Network Security
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• 제22권9호
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• pp.316-326
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• 2022

The prompt development in the field of video is the outbreak of online services which replaces the television media within a shorter period in gaining popularity. The online videos are encouraged more in use due to the captions displayed along with the scenes for better understandability. Not only entertainment media but other marketing companies and organizations are utilizing videos along with captions for their product promotions. The need for captions is enabled for its usage in many ways for hearing impaired and non-native people. Research is continued in an automatic display of the appropriate messages for the videos uploaded in shows, movies, educational videos, online classes, websites, etc. This paper focuses on two concerns namely the first part dealing with the machine learning method for preprocessing the videos into frames and resizing, the resized frames are classified into multiple actions after feature extraction. For the feature extraction statistical method, GLCM and Hu moments are used. The second part deals with the deep learning method where the CNN architecture is used to acquire the results. Finally both the results are compared to find the best accuracy where CNN proves to give top accuracy of 96.10% in classification.

• 유통과학연구
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• 제20권6호
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• pp.75-86
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• 2022

Purpose: This research aims to provide empirical evidence on the impact of digital literacy on behavioural intention regarding using technology for distribution of higher education. Design, Methodology, and Approach: Quantitative analysis was carried out using Covariance-Based Structural Equation Model with data collected from 901 students who fully experienced 2-year study online at different universities in Vietnam. The structural model was built with digital literacy as the primary indicator and other variables were included based on modified version of Unified Theory of Acceptance and Use of Technology (UTAUT2) by adopting performance expectancy, effort expectancy, social influence, habit, and hedonic motivation variables specifically for education sector. Self-efficacy was added to eliminate possible bias in technology acceptance. Results: From the results of model estimation, digital literacy presented positive impact on the online distribution of higher education in Vietnam. The mediating effects of various indicators such as performance expectancy, effort expectancy, social influence, habit, hedonic motivation, and self-efficacy are significantly determined by research model. Conclusion: The higher level of digital literacy of the students, the more likely that they will use technology in higher education study, especially online learning. Additionally, the mediating effects of indicators from the UTAUT2 theoretical model were also evident to be positively significant.

• 통상정보연구
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• 제18권2호
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• pp.27-51
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• 2016

본 연구의 목적은 우리나라 B2C 전자상거래 촉진요인과 온라인쇼핑시장 및 해외직접구매와의 상관관계를 분석함으로써 물류기업들의 물류운영전략 수립에 시사점을 제공하는데 있다. 본 연구는 문헌연구를 통하여 B2C 전자상거래 촉진요인을 도출하고, 전자상거래 촉진요인과 국내 온라인쇼핑 및 해외직접구매와의 인과관계를 실증 분석함으로써 B2C 전자상거래 시대 우리나라 택배서비스기업들의 과제 및 성공적 물류운영전략을 제안하고 있다. 본 연구에서는 B2C 전자상거래 촉진요인들이 국내 온라인쇼핑거래액 및 해외직접수입 실적에 미치는 영향을 파악하기 위해 두 가지 ARDL 모형을 설정하였다. 모형의 분석결과, 신용카드 이용건수, 가구당 처분가능소득, 환율, 실질GDP, 정보통신 부문 설비투자, 초고속인터넷가입자수, 인터넷 프로토콜 IPV4 보유수, 15세 이상 인구 등의 변수가 종속변수에 영향을 미치는 것으로 나타났다. 향후 온라인 모바일 기술 및 국민들의 경제수준이 고양됨에 따라 B2C 전자상거래 기업 및 물류기업들은 최적의 택배 물류서비스 수행을 위한 고도의 전략적 접근이 필요한 시점이다.