• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.333-333
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• 2000

When the generalized singular perturbation method is used for model reduction, the state variables of the original system is reconstructed from the reduced order model. The state reduction error is defined, which shows how well the reconstructed state variables approximate the state variables of the original system equation.

• 대한가정학회지
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• 제38권12호
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• pp.111-129
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• 2000

The purpose of this study is to investigate the level of consumer instantly impulse buying in cuber market user. Also this study analyzes causal effect on consumer instantly impulse purchasing by demographic and social, place and promotion, consumer emotion state, and consumer internal and psychological variables. The data had been collected from on-line research method with 1,034, as using cuber market. The major statistical methods used for data analysis are frequency, percentile, mean, factor analysis, multiple regression analysis, Pearson's correlation analysis, and path analysis. The result of causal effect analysis were as follows; First, the variables affecting possession oriented materialism were sex and age. Second, the variables affecting self-control were sex, income, account of credit card, and instantly state of mind. Third, variables directly affecting instantly impulse purchasing were serif employed, banner advertisement, experience of cuber shopping, shopping mall pattern, instantly state of mind, purpose of shopping, happiness and success oriented materialism, and self-control. Also sex, income account of credit card, and instantly state of mind emerge to indirectly effect via self-control. Especially, the variables of success oriented materialism and instantly state of mind influenced on the highest of relative variables in consumer instantly impulse purchasing.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 하계학술대회 논문집
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• pp.555-558
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• 1991

The IESF(Integral Error and State Feedback) controller, which incorporates state feedback as a modern control scheme and integral action as a classical control scheme, has better performance than that of the conventional PID controller in linear time-invariant systems. The IESF controller requires the measurement of all the state variables. But, unfortunately, it may be difficult or impossible to measure all state variables in many applications. And the IESF controller is applicable only to pole-assignable linear time-invariant system without time delay. In this paper, new IESF controller structure was proposed which performs feedback with only measurable state variables. In order to estimate the unmeasurable state variables. It was adopted the filter mode by full-order obserber. The good performance and effectiveness of the proposed controller was confirmed by computer simulation.

• Journal of Advanced Marine Engineering and Technology
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• 제31권4호
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• pp.462-467
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• 2007

The design and synthesis of a state feedback controller assumes the feedback of all state variables of the system. However, some state variables are not physical quantifies so that sensors may not be available, or may be too expensive to measure. Hence, a state observer can be an alternative to estimate unmeasurable state variables. This paper therefore presents a scheme for state observer-based stabilization control of inverted pendulum systems. The feedback gain matrices of both the state feedback controller and the state observer are tuned by real-coded genetic algorithms(RCGAs) such that the given performance indices are minimized. The proposed method is demonstrated through simulations.

• 대한전기학회논문지
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• 제41권7호
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• pp.773-783
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• 1992

There have been several control schemes for the single input systems with unmeasurable state variables using variable structure control(VSC) theory. However, each of them is a study on the systems which can be represented in the phase canonical form or non-phase canonical form dynamic equation separately. As these control algorithms have difficulties in practical application by its theoretical limitations, in this paper we propose a new VSC theory which overcomes those limitations, in this paper we propose a new VSC theory which overcomes those limitations of proposed schemes. This new control scheme can be realized for the general linear systems which have unmeasurable state variables. And the switching function of this VSS algorithm consists of measurable state variable function(reduced-order switching function) and its derivatives. Also in the construction of control imput only measurable state variables are used.

• 제어로봇시스템학회논문지
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• 제14권6호
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• pp.595-602
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• 2008

In this paper, performance of the initial alignment for INS whose attitude is not leveled is investigated. Observability of the initial alignment filter is analyzed and estimation errors of the estimated state variables are derived. First, the observability is analyzed using the rank test of observability matrix and the normalized error covariance of the Kalman filter based on the 10-state model. In result, it can be seen that the accelerometer biases on horizontal axes are unobservable. Second, the steady-state estimation errors of the state variables are derived using the observability equation. It is verified that the estimates of the state variables have errors due to the unobservable state variables and the non-leveling tilt angles of a vehicle containing the INS. Especially, this paper shows that the larger the tilt angles of the vehicle are, the larger the estimation errors corresponding to the sensor biases are. Finally, it is shown that the performance of the 8-state model excepting the accelerometer biases on horizontal axes is better than that of the 10-state model in the initial alignment by simulation.

• 한국초등과학교육학회지:초등과학교육
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• 제40권3호
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• pp.343-365
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• 2021

본 연구는 초등학교 5~6학년을 대상으로 과학 문제 대면 상황에서 학습자 변인이 상태호기심 및 상태불안 유발에 미치는 영향을 밝히는 데 목적이 있다. 상태호기심 및 상태불안 유발에 영향을 줄 것으로 예상되는 학습자 변인으로 과학호기심, 흥미, 인지욕구, 과학자아개념, 과학불안, 사전지식, 학생이 인식한 과제난이도를 선정하였다. 분석 결과, 과학 문제 대면 상황에서 유발되는 상태호기심에 유의한 영향을 미치는 변인은 흥미, 인지욕구, 과학호기심, 사전지식 순으로 나타났으며, 이들 변인은 모두 정적인 영향을 미쳤다. 또한 과학 문제 대면 상황에서 유발되는 상태불안에 유의한 영향을 미치는 변인은 과학 불안, 학생이 인식한 과제난이도, 인지욕구, 과학자아개념, 사전지식 순으로 나타났다. 이중 사전지식만 상태불안 유발에 부적인 영향을 미쳤고 나머지 변인들은 정적인 영향을 미쳤다. 본 연구의 결과는 과학학습에서 학생의 정서적 상태에 대한 이해의 폭을 넓히고, 과학 학습에서 유발되는 상태호기심 및 상태 불안 연구에 대한 이론적 토대를 마련할 것으로 기대된다.

• 조명전기설비학회논문지
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• 제12권4호
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• pp.136-145
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• 1998

본 논문에서는 몰드변압기 예방진단을 위해 정상상태와 비정상상태 몰드변압기의 진동신호의 FFT 및 시계열 분석에 관해 연구하였다. 실험올 위한 제어변수들로 공급전압, 부하전류 및 주위온도를 변화시키면서, 진동신호 크기, 주파수 스펙트럼 및 시계열 계수와 같은 측정변수들을 분석하였다. 제어변수 변화에 의한 진동선호는 권선표변과 철섬에 부착된 가속도센서로 측정되었으며, 이 신호들은 중폭기를 거쳐 데이터 수집장치에서 측정변수들로 계산되었다. 또한, 정 상상태 분석 후, 몰드변압기의 구조적 변형올 모의하였다. 비정상상태 진동신호는 정상상태와 같은 제어변수 변화 에 의해 측정되었다. 연구 결과, 정상상태와 비정상상태 진동신호는 수직진동신호와 수평진동신호를 비교하여 분석함으혹써 구별이 가능하였다.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2012년도 춘계학술발표대회 논문집
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• pp.419-424
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• 2012

This paper discusses the state-of-the-art techniques in real-time state estimation for the Smart Microgrids. The most popular method used in traditional power system state estimation is a Weighted Least Square(WLS) algorithm which is based on Maximum Likelihood(ML) estimation under the assumption of static system state being a set of deterministic variables. In this paper, we present a survey of dynamic state estimation techniques for Smart Microgrids based on Belief Propagation (BP) when the system state is a set of stochastic variables. The measurements are often too sparse to fulfill the system observability in the distribution network of microgrids. The BP algorithm calculates posterior distributions of the state variables for real-time sparse measurements. Smart Microgrids are modeled as a factor graph suitable for characterizing the linear correlations among the state variables. The state estimator performs the BP algorithm on the factor graph based the stochastic model. The factor graph model can integrate new models for solar and wind correlation. It provides the Smart Microgrids with a way of integrating the distributed renewable energy generation. Our study on Smart Microgrid state estimation can be extended to the estimation of unbalanced three phase distribution systems as well as the optimal placement of smart meters.

• 유통과학연구
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• 제22권3호
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• pp.59-70
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• 2024

Purpose: This study aimed to develop a strategic business conceptual model for large state plantations in West Java Province and Banten Province, Indonesia. The model was built through causal relationships and interrelationships between marketing strategies and business strategies that affect business performance on large state plantations. The plantation sector provides the largest contribution to gross domestic product and is an important part of national food distribution efforts. Research design, data, and methodology: This study used a literature review adapted from Pret and Logan (2019), which followed the guidelines of Tranfield et al. (2003), derived from the Scopus website with Q1/Q2 quartiles and inclusion/exclusion criteria published from 2012 to 2021. Results: Based on a systematic literature review approach, we constructed the strategic business conceptual model for large state plantations based on a combination of four causal and interrelationship variables that affect business performance, namely, industry attractiveness, unique capabilities, innovation management, and collaboration strategy. Conclusions: This research explains the relationship between industry attractiveness variables and unique capability as independent variables that can affect business performance through collaboration strategy and innovation management as intervening variables in the plantation sector, especially large state plantations, which have not been found in previous studies.