• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1994년도 Proceedings of the Korea Automatic Control Conference, 9th (KACC) ; Taejeon, Korea; 17-20 Oct. 1994
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• pp.498-503
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• 1994

The paper demonstrates that holon networks can be used effectively for identification of nonlinear dynamical systems. The emphasis of the paper is on modeling of complicated systems which have a great deal of uncertainty and unknown interactions between their elements and parameters. The concept of applying a quantitative model building, for example, to environmental or ecological systems is not new. In a previous paper we presented a holon network model as an another alternative to quantitative modeling. Holon networks have a hierarchical construction where each level of hierarchy consists of networks with reciprocal actions among their elements. The networks are able to evolve by self-organizing their structure and adapt their parameters to environments. This was achieved by an autonomous decentralized adaptation algorithm. In this paper we propose a new emergent evolution algorithm. In this algorithm the initial holon networks consists of only a few elements and it grows gradually with each new observation in order to fit their function to the environment. Some examples show that this algorithm can lead to a network structure which has sufficient flexibility and adapts well to the environment.

• International Journal of Automotive Technology
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• 제8권3호
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• pp.383-394
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• 2007

Due to the clutch's non-linear dynamics, time-delays, external disturbance and parameter uncertainty, the automated clutch is difficult to control precisely during the launch process or automatic mechanical transmission (AMT) vehicles. In this paper, an enhanced fuzzy sliding mode controller (EFSMC) is proposed to control the automated clutch. The sliding and global stability conditions are formulated and analyzed in terms of the Lyapunov full quadratic form. The chattering phenomenon is handled by using a saturation function to replace the pure sign function and fuzzy logic adaptation system in the control law. To meet the real-time requirement of the automated clutch, the region-wise linear technology s adopted to reduce the fuzzy rules of the EFSMC. The simulation results have shown hat the proposed controller can achieve a higher performance with minimum reaching time and smooth control actions. In addition, our data also show that the controller is effective and robust to the parametric variation and external disturbance.

• 종양간호연구
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• 제12권3호
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• pp.237-245
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• 2012

Purpose: The purpose of this study was to identify attributes of the concept of cancer survivorship. Methods: Walker & Avant's concept analysis framework (2005) was used to review the medical & nursing text books, medical and nursing research articles related to cancer survivorship and published from 1985 to 2011. Results: There were nine aspects of the concept of cancer survivorship: A process, liminality, uncertainty, life-changing experience, complexity, unique experience, duality of positive and negative aspects, partnership, and need for support. Antecedents of cancer survivorship were cancer diagnosis and perception as a cancer survivor. Empirical referents of cancer survivorship were survival rate, quality of life, adaptation to the survivorship experience, and health-related hardiness, social support, spirituality, and health behavior. The consequences of cancer survivorship were effects on the physical, psychosocial, spiritual and socio-economic well-being of the patients. Conclusion: This concept analysis of cancer survivorship is expected to contribute to promotion of survivorship care in the clinical field by removing conceptual ambiguity and confirming the true meaning of survivorship care.

• 농업과학연구
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• 제48권2호
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• pp.311-331
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• 2021

Climate change with extreme hydrological events has become a significant concern for agricultural water systems. Climate change affects not only irrigation availability but also agricultural water requirement. In response, adaptation strategies with soft and hard options have been considered to mitigate the impacts from climate change. However, their implementation has become progressively challenging and complex due to the interconnected impacts of climate change with socio-economic change in agricultural circumstances, and this can generate more uncertainty and complexity in the adaptive management of the agricultural water systems. This study was carried out for the agricultural water supply system in Seongju dam watershed in Seonju-gun, Gyeongbuk in South Korea. The first step is to identify system disturbances. Climate variation and socio-economic components with historical and forecast data were investigated Then, as the second step, problematic trends of the critical performance were identified for the historical and future climate scenarios. As the third step, a system structure was built with a dynamic hypothesis (causal loop diagram) to understand Seongju water system features and interactions with multiple feedbacks across system components in water, agriculture, and socio-economic sectors related to the case study water system. Then, as the fourth step, a mathematical SD (system dynamics) model was developed based on the dynamic hypothesis, including sub-models related to dam reservoir, irrigation channel, irrigation demand, farming income, and labor force, and the fidelity of the SD model to the Seongju water system was checked.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1990년도 한국자동제어학술회의논문집(국제학술편); KOEX, Seoul; 26-27 Oct. 1990
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• pp.963-968
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• 1990

An iterative learning control scheme for tracking control of a class of uncertain nonlinear systems is presented. By introducing a model reference adaptive controller in the learning control structure, it is possible to achieve zero tracking of unknown system even when the upperbound of uncertainty in system dynamics is not known apriori. The adaptive controller pull the state of the system to the state of reference model via control gain adaptation at each iteration, while the learning controller attracts the model state to the desired one by synthesizing a suitable control input along with iteration numbers. In the controller role transition from the adaptive to the learning controller takes place in gradually as learning proceeds. Another feature of this control scheme is that robustness to bounded input disturbances is guaranteed by the linear controller in the feedback loop of the learning control scheme. In addition, since the proposed controller does not require any knowledge of the dynamic parameters of the system, it is flexible under uncertain environments. With these facts, computational easiness makes the learning scheme more feasible. Computer simulation results for the dynamic control of a two-axis robot manipulator shows a good performance of the scheme in relatively high speed operation of trajectory tracking.

• 조명전기설비학회논문지
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• 제20권3호
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• pp.62-68
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• 2006

본 논문에서는 3상 AC/DC 컨버터의 적응 입출력 선형화와 영점 동특성식 제어 기법을 제안한다. 컨버터 출력 dc전압이 단위 역률을 유지하도록 회전 d-q 프레임의 q축 전류가 영의 값으로 유지되고 출력전압은 주어진 기준전압 $V_r$을 추종하도록 제어된다. 제안된 제어기법은 적응 프로세스를 이용해 파라미터 불확실성과 부하 전류 변화에 대해 견실하다. 제안된 제어 기법의 효용성과 타당성을 보이기 위해 시뮬레이션 연구가 수행되었다.

• Child Health Nursing Research
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• 제18권3호
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• pp.101-108
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• 2012

Purpose: This study was designed to analyze recent trends in research about caregivers of hospitalized children in Korea and to suggest future research directions in this area. Methods: Eighty one studies selected from http://www.kan.or.kr, www.childnursing.or.kr, www.riss4u.net, and www.ndsl.kr published from 1995 to 2011 were used. The analysis framework of concepts was derived from client domain (Kim, 2000) and knowledge type (Kim et al., 2004). Results: In terms of research design, nonexperimental studies (82.7%) were the most frequent, followed by experimental studies (14.8%) and qualitative studies (2.5%). Mothers were the most frequent caregivers, and hospitalization was the most frequent health problem of the children. In terms of categories of the concepts, 35 (39.3%) studies included essentialistic concepts like coping and adaptation, 15 (16.9%) studies included problematic concepts like anxiety and uncertainty, and 39 (43.8%) studies included health-care experiential concepts like educational needs and nursing needs. In term of knowledge types, there were 35 (39.3%) studies of the explanatory knowledge type, 44 (49.5%) descriptive ones, and 10 (11.2%) prescriptive ones. Conclusion: The results indicate that further research is necessary on problematic concepts and prescriptive knowledge types for child health nursing practice which will lead to expanding nursing knowledge.

• International Journal of Ocean System Engineering
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• 제3권2호
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• pp.50-60
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• 2013

This paper presents a novel approach to the design of an adaptive fuzzy sliding mode controller for depth control of an autonomous underwater vehicle (AUV). So far, AUV's dynamics are highly nonlinear and the hydrodynamic coefficients of the vehicles are difficult to estimate, because of the variations of these coefficients with different operating conditions. These kinds of difficulties cause modeling inaccuracies of AUV's dynamics. Hence, we propose an adaptive fuzzy sliding mode control with novel fuzzy adaptation technique for regulating vertical positioning in presence of parametric uncertainty and disturbances. In this approach, two fuzzy approximator are employed in such a way that slope of the linear sliding surface is updated by first fuzzy approximator, to shape tracking error dynamics in the sliding regime, while second fuzzy approximator change the supports of the output fuzzy membership function in the defuzzification inference module of fuzzy sliding mode control (FSMC) algorithm. Simulation results shows that, the reaching time and tracking error in the approaching phase can be significantly reduced with chattering problem can also be eliminated. The effectiveness of proposed control strategy and its advantages are indicated in comparison with conventional sliding mode control FSMC technique.

• 동력기계공학회지
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• 제21권4호
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• pp.42-50
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• 2017

A velocity controller using a modified model reference adaptive controller (M-MRAC) and a projection operator for a fish sorting belt conveyor system with uncertainty parameters, input saturation and bounded disturbances is proposed in this paper. To improve the tracking performance and robustness of the proposed controller in the presence of bounded disturbances, the followings are done. Firstly, the reference model for the conventional model reference adaptive controller (CMRAC) is replaced by a modified reference model for a M-MRAC to reduce unexpected high frequency oscillation in control input signal when the adaptation rate is increased. Secondly, estimated parameters in an adaptive law are varied smoothly under bounded external disturbances and a projection operator is utilized in an adaptive law for the proposed M-MRAC controller to be robust. Thirdly, an auxiliary error vector is introduced for compensating the error dynamics of the system when the saturation input occurs. Finally, the experimental results are shown to verify the better effectiveness and performance of the proposed controller under the bounded disturbance and saturated input than that of a CMRAC.

• 한국컴퓨터정보학회논문지
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• 제6권3호
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• pp.91-101
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• 2001

본 연구는 기업 간 인터넷 전자상거래의 개념과 도입효과를 고찰하고, 기존의IT/IS 도입요인의 연구를 토대로 하여 기업 간 인터넷 전자상거래의 도입에 영향을 미치는 핵심적인 요인을 분석하여 전자상거래의 확산에 기여하고자 하였다. 이에 어떠한 요인들이 기업 간 전자상거래 도입에 영향을 미치는지를 분석하였으며 도입요인으로서 환경 요인은 시장 불확실성요인과 산업 내 경쟁요인으로, 조직 요인은 조직규모, 의사결정의 집중도와 업무의 표준화 요인, 최고 경영층의 지원요인으로 세분되며, 정보시스템 요인은 IS/IT 기반구조 요인과 정보기술간 통합정도 요인으로 구분된다. 따라서 기업간 인터넷 전자상거래 도입을 기업정보시스템의 도입으로 간주하여, IT/IS 도입에 관한 이론적 근거를 토대로 인터넷을 사용한 기업 간 전자상거래에 도입요인에 대한 핵심적인 측정변수를 도출하고자 한다. 이러한 연구를 통하여 기업 간 인터넷 전자상거래를 도입하려는 기업에게 도입 여부 및 시기에 대한 의 사 결정의 지침을 제공하고 기업이 전자상거래를 성공적으로 도입하는데 도움을 주고, 나아가 전자상거래를 확대시키는데 기여할 수 있을 것이다.