• Journal of the Korean Institute of Intelligent Systems
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• v.21 no.4
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• pp.423-429
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• 2011

This paper deals with the observer-based decentralized fuzzy controller design for nonlinear interconnected system for PEMFC. The nonlinear interconnected system is represented by a Takagi-Sugeno (T-S) fuzzy model. Based on T-S fuzzy interconnected system, the fuzzy observer and the decentralized fuzzy controller are designed. The stability condition of the closed-loop system with the proposed controller is represented to the linear matrix inequality (LMI) form, and the observer and control gain s are obtained by LMI. An example is given to show the verification discussed throughout the paper.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.7 no.1
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• pp.1-6
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• 2007

The SVDD (support vector data description) is one of the most well-known one-class support vector learning methods, in which one tries the strategy of utilizing balls defined on the feature space in order to distinguish a set of normal data from all other possible abnormal objects. Recently, with the objective of generalizing the SVDD which treats all training data with equal importance, the so-called D-SVDD (density-induced support vector data description) was proposed incorporating the idea that the data in a higher density region are more significant than those in a lower density region. In this paper, we consider the problem of further improving the D-SVDD toward the use of a partial reference set for testing, and propose an LMI (linear matrix inequality)-based optimization approach to solve the improved version of the D-SVDD problems. Our approach utilizes a new class of density-induced distance measures based on the RSDE (reduced set density estimator) along with the LMI-based mathematical formulation in the form of the SDP (semi-definite programming) problems, which can be efficiently solved by interior point methods. The validity of the proposed approach is illustrated via numerical experiments using real data sets.

• Journal of Preventive Medicine and Public Health
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• v.40 no.6
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• pp.431-438
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• 2007

Objectives : The aim of this study is to summarize the current conditions and implications of health inequalities in South Korea. Methods : Through a literature review of empirical studies and supplementary analysis of the data presented in the 1998, 2001, and 2005 KNHANEs, we evaluated the extent and trends of socioeconomic inequalities in both health risk factors, such as smoking, physical activity, and obesity, and outcomes, such as total mortality, subjective poor health status by self-reports and metabolic syndrome. Relative risks and odds ratios were used to measure differences across socioeconomic groups, and the relative index of inequality was used to evaluate the changes in inequalities over time. Results : We found clear inequalities to various degrees?in most health indicators. While little change was observed in mortality differences over time, the socioeconomic gaps in risk factors and morbidity have been widening, with much larger differences among the younger population. Conclusions : Socioeconomic inequalities are pervasive across various health indicators, and some of them are increasing. The trends in socioeconomic inequalities in health should be carefully monitored, and comprehensive measures to alleviate health inequalities are needed, especially for young populations.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.52 no.4
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• pp.189-197
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• 2003

The problem of designing a parallel feedforward compensator (PFC) is considered for a class of non-square linear systems such that the closed-loop system is strictly passive. If a given square system has (vector) relative degree one and is weakly minimum phase, the system can be rendered passive by a state feedback. However, when the system states are not always measurable and the given output is considered, passivation (i.e. rendering passive) of a non-minimum phase system or a system with high relative degree cannot be achieved by any other methodologies except by using a PFC. To passivate a non-square system we first determine a squaring gain matrix and design a PFC such that the composite system has relative degree one and is minimum phase. Then the system is rendered strictly passvie by a static output feedback law. Necessary and sufficient conditions for the existence of the PFC and the squaring gain matrix are given by the static output feedback formulation, which enables to utilize linear matrix inequality (LMI). As an application of the scheme, an alternative way of replacing the role of velocity measurements is provided for the PD-control law of a convey-crane system.

• Journal of the Korean Institute of Intelligent Systems
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• v.18 no.2
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• pp.151-156
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• 2008

This paper presents the stability analysis and design for a sampled-data fuzzy control system with neutral type of time delay, which is formed by a nonlinear plant and a sampled-data fuzzy controller connected in a closed loop. The sampling activity and neutral type of time delay will complicate the system dynamics and make the stability analysis much more difficult than that for a pure continuous-time fuzzy control system. Based on the fuzzy-model-based control approach, LMI(linear matrix inequality)-based stability conditions are derived to guarantee the nonlinear networked system stability. An application example will be given to show the merits and design a procedure of the proposed approach.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.6
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• pp.453-462
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• 2016

This paper proposes a torque control method for surface mounted permanent magnetic synchronous motor (PMSM) driven by a 2-level voltage source driven inverter, which has fast torque response and small torque ripple. The proposed torque control method follows the finite control set model predictive control (FCS-MPC) strategy. A reference state is derived at each time step for the given time varying torque reference and the cost index is defined so that the tracking error for this reference state should be penalized. The choice of an optimal output voltage vector is made first from the 6 possible active voltage vectors of the 2-level voltage source inverter. Then a modulation factor for the chosen optimal voltage vector is obtained so that the torque ripple can be reduced further. It is shown that the proposed FCS-MPC control method yields fast torque tracking response and small torque ripple through simulation and experiments.

• Journal of Korean Biological Nursing Science
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• v.19 no.2
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• pp.98-106
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• 2017

Purpose: This study aimed to analyze the relationships between the factors affecting health levels of the elderly in rural areas. Methods: Subjects were 257 elderly people residing in rural areas of six cities and Gangwon Province. Data was collected through questionnaires (demographic and socioeconomic status, social resources, health behaviors, physical environment, psychological tendency and general health levels) and was analyzed by using multiple regression and Sobel test. Results: The demographic and socioeconomic characteristics of the subjects exerted statistically significant influence on their social resources, health behaviors, physical environment, and psychological tendencies. The demographic and socioeconomic characteristics, social resources, health behaviors, physical environment, and psychological tendencies, in turn, exerted a statistically significant influence on the health level. The social resources had mediating effects on the relationship between income, one of the demographic and socioeconomic characteristics, and health level. The residential environments had mediating effects on the relationship between income and health level. The psychological tendency had mediating effects on the relationship between income and health level. Conclusion: This study suggests that income is an important factor affecting health level among rural elderly people. In addition, social resources, health behaviors, physical environment, and psychological tendencies among them also affect health level, so it is necessary to make strategies to improve these factors.

• Journal of Families and Better Life
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• v.1 no.2
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• pp.107-125
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• 1983

This study aimed to clarify the attitude toward marriage, mate selection and sexual consciousness of japanese unmarried women students whom are believed in drastic change in a overall social value system and norm due to the introduction of western civilization, so as to provide some information of the same subject of our young women in similar situation. Survey was carried out for 177 unmarried Japanese women students of 3 Universities located in Osaka prefecture situation. Data were collected by means of Questionnaire and analyzed by SPSS BATCH SYSTEM. Result are as follows; 1) Pattern of mate selection- An increasing tendency of love match is recognized 2) Attitude to marriage-94.0% of correspondences want to marry and proper age of marriage, they think, is between 22-25 years. 3) Love-marriage relation- most correspondences answered that love is a prior condition for marriage, however, 32.8% of correspondences think, love can be built after the marriage. 4) Dating- most correspondences want free dating, however, they fell that they are lacking for opportunity and they are not confident in the selection of proper mate. 5) Premarital sexual intercourse-most correspondences show a very generous attitude toward premarital sexual intercourse if they are in love and this attitude becomes more remarkable among love match makers. 6) Equality of sexes-most correspondences answered that as women are different in physiological function from men, distinctive social roles of both sexes and the inequality of sexes are inevitable.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.12
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• pp.2189-2196
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• 2016

This paper proposes a new finite control set-model predictive control (FCS-MPC) method for induction motors. In the method, the reference state that satisfies the given torque and rotor flux requirements is derived. Cost indices for the FCS-MPC are defined using the state tracking error, and a linear matrix inequality is formulated to obtain a proper weighting matrix for the state tracking error. The on-line procedure of the proposed FCS-MPC comprises of two steps: select the output voltage vector of the two level inverter minimizing the cost index and compute the optimal modulation factor of the minimizing output voltage vector in order to reduce the state tracking error and torque ripple. The steady state tracking error is removed by using an integrator to adjust the reference state. The simulation and experimental results demonstrated that the proposed FCS-MPC shows good torque, rotor flux control performances at different rotating speeds.

• Journal of the Korean Institute of Intelligent Systems
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• v.17 no.4
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• pp.483-487
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• 2007

This paper is concerned with the observer design problem for linear neutral systems with time-varying delays. The problem addressed is that of designing a full-order observer that guarantees the exponential stability of the error system. An effective algebraic matrix equation approach is developed to solve this problem. In particular, both observer analysis and design problems are investigated. Sufficient conditions for a linear neutral system to be stable are first established. Furthermore, an illustrative example is used to demonstrate the validity of the proposed design procedure.