• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.233-233
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• 2000

Direct torque control (DTC) scheme provides a very quick torque response without the complex field-orientation block and inner current regulation loop. DTC is known as an appropriate scheme for high power induction motet drives because it can be used at lower switching frequency. There are two major drawbacks with the application of DTC schemes : one is large current harmonics due to flux drooping in a low speed range, the other is that the inverter switching frequency is varying according to motor parameters and operating speed. Switching devices in the power electronics drives should be supported for relatively high switching frequency. In this paper, a P-type fuzzy controller to realize the variable switching sector scheme and a PID-type fuzzy switching frequency regulator are adopted. A meaningful contribution of this paper is to propose a simple realization scheme of the fuzzy switching frequency regulator. Simulation results show the effectiveness of those propositions.

• Proceedings of the KIPE Conference
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• 2001.12a
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• pp.11-14
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• 2001

Direct torque control (DTC) scheme provides a very quick torque response without the complex field-orientation block and inner current regulation loop. DTC is known as an appropriate scheme for high power induction motor drives because it can be used at lower switching frequency There are a major drawbacks with the application of DTC schemes it is large current harmonics due to flux drooping in a low speed range. In order to solve the problem, the fuzzy variable switching sector scheme are adopted in this paper. A meaningful contribution of this paper is to propose a simple realization scheme of the fuzzy variable switching sector technique. Experimental results show the effectiveness of this proposition.

• The Transactions of the Korean Institute of Power Electronics
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• v.7 no.2
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• pp.137-148
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• 2002

Direct Torque Control(DTC) is considered to be an useful control scheme of high performance induction motor drives because the scheme provides a quick torque response without requiring the complex field-orientation block and inner current regulation loop. Among a few drawbacks of the conventional DTC scheme, large current harmonics due to flux drooping phenomenon in a low speed range may be the major difficulty In order to remove the difficulty, a fuzzy variable switching sector scheme and its real-time implementation algorithm are proposed in this paper. A DSP based control board is designed for the Induction motor drives with the DTC scheme including the fuzzy switching sector algorithm. Simulation and experimental results show the effectiveness of the proposed scheme.

• Journal of the Korean Institute of Telematics and Electronics T
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• v.35T no.2
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• pp.39-47
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• 1998

It has been known that variable structure control(VSC) has theoretically powerful control technique of providing fast response, no overshoot, and very robust control with respect to system parameter variations and disturbances. However, the technique has not become more widely extended in the industrial circles because chattering phenomenon which may excite high-frequency unmodelled plant dynamics and damage to system components exists. In this paper, a modified variable structure control(MVSC) is developed to alleviate these problems which are applied to the position control of induction motor. While the conventional VSC makes the structure of the system change with high-frequency switching on the center of the one switching surface, in the MVSC two switching surface are used to establish a sliding sector. The structure of the system will be changed with low-frequency switching. Therefore, the proposed algorithm has the properties of reducing chattering, retaining the benefits achieved in the conventional VSC, and working even under the influences of parameter variations. Experimental results show the effectiveness of the control strategy proposed here for the position control of induction motor.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.10
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• pp.865-874
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• 2020

In Vietnam, the airline service sector plays an important economic role. However, it is a complicated industry that is open to failures. Negative emotions are an essential variable for the airline service industry because they can trigger a variety of coping behaviors that affect consumer loyalty as well as the image and reputation of the airline service providers. However, negative emotions and the accompanying coping behaviors are often investigated partially or as separate issues, thus leading to an incomplete understanding. This study is conducted to fill this gap by proposing and testing the causal relationship between negative emotions (anger, frustration, regret) and coping behaviors (complaint, negative word-of-mouth (WOM), and switching intention) in the context of the airline industry. Eight research hypotheses are tested. Using the partial least squares structural equation modeling (PLS-SEM) on a sample of 587 passengers in Vietnam, the empirical results show that anger and frustration influence complaints, negative WOM, and switching intention, while regret leads to switching intention and negative WOM. Thus, the research has important academic and practical implications. The empirical outcome could be of major importance for airline companies in planning to provide new services and achieve high performance in the long run.

• Environmental and Resource Economics Review
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• v.25 no.3
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• pp.377-401
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• 2016

This study analyzes how much cost the power generation and energy sector in South Korea have to bear due to the introduction of emissions trading scheme during 2016 - 2017. To this end, the data on the seventh basic plan for long-term electricity supply and demand is applied to the electricity market simulation model called M-Core, and then the model forecasts carbon dioxide emissions to compare with the free emission allowances in the first national emissions permit allocation plan. The main results are as follows. Carbon dioxide emissions are estimated to be less in 2016 but more than the free emission allowances in 2017. When the price of the allowances is changed from \10,000/ton to \20,000/ton, the cost of purchasing the allowances is ranged from \70 billion to \140 billion. Under the assumption that CO2 cost is incorporated into the variable cost, a reversal of merit order between coal and LNG generation takes place when the price of the allowances exceeds \80,000/ton.