• Journal of Electrical Engineering and Technology
• /
• v.7 no.4
• /
• pp.513-523
• /
• 2012

For precisely regulating the speed of a permanent magnet synchronous motor system with unknown load torque disturbance and disturbance inputs, an LMI-based sliding mode control scheme is proposed in this paper. After a brief review of the PMSM mathematical model, the sliding mode control law is designed in terms of linear matrix inequalities (LMIs). By adding an extended observer which estimates the unknown load torque, the proposed speed tracking controller can guarantee a good control performance. The stability of the proposed control system is proven through the reachability condition and an approximate method to implement the chattering reduction is also presented. The proposed control algorithm is implemented by using a digital signal processor (DSP) TMS320F28335. The simulation and experimental results verify that the proposed methodology achieves a more robust performance and a faster dynamic response than the conventional linear PI control method in the presence of PMSM parameter uncertainties and unknown external noises.

• 제어로봇시스템학회:학술대회논문집
• /
• 2003.10a
• /
• pp.433-437
• /
• 2003

Quantitative Feedback Theory (QFT) is one of effective methods of robust controller design. In QFT design we can considers the phase information of the perturbed plant so it is less conservative than $H_{\infty}$ and ${\mu}$-synthesis methods and as be shown, it is more transparent than the sensitivity reduction methods mentioned . In this paper we want to overcome the major drawback of QFT method which is lack of an automatic method for loop-shaping step of the method so we focus on the following problem: Given a nominal plant and QFT bounds, synthesize a controller that achieves closed-loop stability and satisfies the QFT boundaries. The usual approach to this problem involves loop-shaping in the frequency domain by manipulating the poles and zeros of the nominal loop transfer function. This process now aided by recently developed computer aided design tools proceeds by trial and error and its success often depends heavily on the experience of the loop-shaper. Thus for the novice and First time QFT user, there is a genuine need for an automatic loop-shaping tool to generate a first-cut solution. Clearly such an automatic process must involve some sort of optimization, and while recent results on convex optimization have found fruitful applications in other areas of control theory we have tried to use LMI theory for automating the loop-shaping step of QFT design.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.9 no.3
• /
• pp.195-202
• /
• 2004

This paper presents a current control strategy to reduce torque ripple of Brushless DC Motor during con)mutation. The torque ripple is mainly caused by the inequality in the rate of change between rising current and decaying one during commutation. And also it is influenced by the shape of real back EMF Therefore, in the proposed control strategy, considering real back EMF a compensation voltage is generated to equalize the rate of change in these commutating currents. And then, by providing the compensation voltage during commutation, the torque ripple can be reduced. The simulation md experimental results verify that the proposed method can reduce the torque and the current ripples significantly.

• Journal of Institute of Control, Robotics and Systems
• /
• v.22 no.6
• /
• pp.453-462
• /
• 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 Intelligence and Information Systems
• /
• v.20 no.3
• /
• pp.19-43
• /
• 2014

The Pareto principle, also known as the 80-20 rule, states that roughly 80% of the effects come from 20% of the causes for many events including natural phenomena. It has been recognized as a golden rule in business with a wide application of such discovery like 20 percent of customers resulting in 80 percent of total sales. On the other hand, the Long Tail theory, pointing out that "the trivial many" produces more value than "the vital few," has gained popularity in recent times with a tremendous reduction of distribution and inventory costs through the development of ICT(Information and Communication Technology). This study started with a view to illuminating how these two primary business paradigms-Pareto principle and Long Tail theory-relates to the success of virtual knowledge collaboration. The importance of virtual knowledge collaboration is soaring in this era of globalization and virtualization transcending geographical and temporal constraints. Many previous studies on knowledge sharing have focused on the factors to affect knowledge sharing, seeking to boost individual knowledge sharing and resolve the social dilemma caused from the fact that rational individuals are likely to rather consume than contribute knowledge. Knowledge collaboration can be defined as the creation of knowledge by not only sharing knowledge, but also by transforming and integrating such knowledge. In this perspective of knowledge collaboration, the relative distribution of knowledge sharing among participants can count as much as the absolute amounts of individual knowledge sharing. In particular, whether the more contribution of the upper 20 percent of participants in knowledge sharing will enhance the efficiency of overall knowledge collaboration is an issue of interest. This study deals with the effect of this sort of knowledge sharing distribution on the efficiency of knowledge collaboration and is extended to reflect the work characteristics. All analyses were conducted based on actual data instead of self-reported questionnaire surveys. More specifically, we analyzed the collaborative behaviors of editors of 2,978 English Wikipedia featured articles, which are the best quality grade of articles in English Wikipedia. We adopted Pareto ratio, the ratio of the number of knowledge contribution of the upper 20 percent of participants to the total number of knowledge contribution made by the total participants of an article group, to examine the effect of Pareto principle. In addition, Gini coefficient, which represents the inequality of income among a group of people, was applied to reveal the effect of inequality of knowledge contribution. Hypotheses were set up based on the assumption that the higher ratio of knowledge contribution by more highly motivated participants will lead to the higher collaboration efficiency, but if the ratio gets too high, the collaboration efficiency will be exacerbated because overall informational diversity is threatened and knowledge contribution of less motivated participants is intimidated. Cox regression models were formulated for each of the focal variables-Pareto ratio and Gini coefficient-with seven control variables such as the number of editors involved in an article, the average time length between successive edits of an article, the number of sections a featured article has, etc. The dependent variable of the Cox models is the time spent from article initiation to promotion to the featured article level, indicating the efficiency of knowledge collaboration. To examine whether the effects of the focal variables vary depending on the characteristics of a group task, we classified 2,978 featured articles into two categories: Academic and Non-academic. Academic articles refer to at least one paper published at an SCI, SSCI, A&HCI, or SCIE journal. We assumed that academic articles are more complex, entail more information processing and problem solving, and thus require more skill variety and expertise. The analysis results indicate the followings; First, Pareto ratio and inequality of knowledge sharing relates in a curvilinear fashion to the collaboration efficiency in an online community, promoting it to an optimal point and undermining it thereafter. Second, the curvilinear effect of Pareto ratio and inequality of knowledge sharing on the collaboration efficiency is more sensitive with a more academic task in an online community.

• Journal of Preventive Medicine and Public Health
• /
• v.51 no.2
• /
• pp.83-91
• /
• 2018

Objectives: One of the main objectives of the Targeted Subsidies Law (TSL) in Iran was to improve equity in healthcare financing. This study aimed at measuring the effects of the TSL, which was implemented in Iran in 2010, on equity in healthcare financing. Methods: Segmented regression analysis was applied to assess the effects of TSL implementation on the Gini and Kakwani indices of outcome variables in Iranian households. Data for the years 1977-2014 were retrieved from formal databases. Changes in the levels and trends of the outcome variables before and after TSL implementation were assessed using Stata version 13. Results: In the 33 years before the implementation of the TSL, the Gini index decreased from 0.401 to 0.381. The Gini index and its intercept significantly decreased to 0.362 (p<0.001) 5 years after the implementation of the TSL. There was no statistically significant change in the gross domestic product or inflation rate after TSL implementation. The Kakwani index significantly increased from -0.020 to 0.007 (p<0.001) before the implementation of the TSL, while we observed no statistically significant change (p=0.81) in the Kakwani index after TSL implementation. Conclusions: The TSL reform, which was introduced as part of an economic development plan in Iran in 2010, led to a significant reduction in households' income inequality. However, the TSL did not significantly affect equity in healthcare financing. Hence, while measuring the long-term impact of TSL is paramount, healthcare decision-makers need to consider the efficacy of the TSL in order to develop plans for achieving the desired equity in healthcare financing.

• Journal of the Korean association of regional geographers
• /
• v.5 no.2
• /
• pp.29-45
• /
• 1999

This study reviewed theories on entrepreneurial local governance and inquired the changing regional policy in Chonnam region. The region became exposure as the direct investment unit of global capital by globalization of capital, the inter-regional competition and the relative reduction of the role and function of nation state. Therefore local government have the relative autonomy and the region is effected as the chosen space by capital according to the free movement of capital. It has been argued that there has been a reorientation of urban governance away from the local provision of welfare and services to a more outward-orientated stance designed to foster and encourage local growth and economic development. These profound changes in the way that cities operate have seen the public sector taking over characteristics once distinctive to the private sector leading many commentators to term such modes of governance as entrepreneurial. In Chonnam region, many local governments are introducing entrepreneurial policies for regional development. It appears as place marketing strategy to attract capital and tourists. This strategy is very important to used identity or culture of region in order to make the attractive region. The entrepreneurial characteristics and strategies appear as image unification of region, commodity development of natural or cultural resource, event and business projects. From this point of view, the entrepreneurial policy that is based upon regional growth can cause the problem of social justice like distributional distortion and inequality.

• Korean Journal of Social Welfare
• /
• v.63 no.3
• /
• pp.187-211
• /
• 2011

This study examines the effects of active labor market policy on unemployment by pooled cross-section time series analysis utilizing panel data of 18 OECD countries, and seeks implications for improvements of the Korean active labor market policy. The results of the analysis are summarized as follows. First, active labor market policy negatively affects unemployment rates. Second, vacational training program among three major active labor market programs has a negative effect on unemployment rates. Third, employment service program and employment subsidy program have partially negative effects on unemployment rates. The implications for the Korean active labor market policy are as follows. First, it is necessary to expand and systematize active labor market policies. Second, vocational training programs should be systematized and professionalized according to labor demand. Third, employment subsidy programs need to be planned and carried out under the condition of minimizing a substitution effect, a displacement effect and a deadweight loss effect. Fourth, employment service programs need to be developed and carried out under the consideration of not only the reduction of unemployment rates but also the prevention of re-unemployment, mitigation of income inequality and improvement of productivity.

• Korean Journal of Social Welfare
• /
• v.61 no.2
• /
• pp.61-84
• /
• 2009

There has been a continuous debate on decentralization of welfare. The proponents of decentralization argue that it will enhance the autonomy of local governments and the efficiency in the provision of service. However, the opponents argue that it will lead to the welfare reduction and the increased inequality among localities. This study attempts to deal with the question, focusing on the evaluation of decentralization reform of Roh Government. The main results are as follows: After the decentralization, local governments has undergone hardships in financing the welfare service, while there is no clear evidence that the local autonomy has enhanced. In respect of fiscal role-sharing, local duties has significantly increased because of the insufficient grants-in-aid for decentralization and inappropriate formula in assessing the grants. In respect of functional role-sharing, the decreased role of central government made it difficult for local governments to provide enough residential institution for the elderly and the disabled. To improve the decentralization reform, deliberate reclassification is needed to decide which item should be transferred to localities. Regarding the characteristic of the projects, social services could be transferred in the long run, while central government should take more responsibilities for the income guarantee and protection for the disadvantaged.

• The Journal of Asian Finance, Economics and Business
• /
• v.6 no.2
• /
• pp.299-307
• /
• 2019

This study aims to explore the theoretical concepts of inclusive development in relation to the spatial context, assessment the disparities in the social and economic development of the regions of Kazakhstan and substantiate the main mechanisms for overcoming them. In this research, authors propose the methodological tools for presenting a standard form of evaluation of social and economic development in the regions of Kazakhstan. In this study used methods, which based on measuring disproportions between the levels of economic and social development of the regions, as well as disproportions between the republican and regional levels. According to the author's methodological approach, complex and integral indexes have calculated over the period 2012-2017 for a number of indicators adapted to the conditions of Kazakhstan. The calculated indexes proposed to use as instruments for measuring the level of the social and economic development. In addition, according the obtained indexes and the results of their ranking can be the basis for the development of regional programs and management decisions. This will improve the targeted support of the population in backward regions in order to ensure inclusive development and improve the quality of life of the population.