• Journal of Power Electronics
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• v.18 no.2
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• pp.445-455
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• 2018

A novel algorithm is proposed to regulate the neutral point potential in neutral point clamped three-level inverters. Oscillations of the neutral point potential and an unbalanced dc-link voltage cause distortions of the output voltage. Large capacitors, which make the application costly and bulky, are needed to eliminate oscillations. Thus, the algorithm proposed in this paper utilizes the finite-control-set model predictive control and the multistage medium vector to solve these issues. The proposed strategy consists of a two-step prediction and a cost function to evaluate the selected multistage medium vector. Unlike the virtual vector method, the multistage medium vector is a mixture of the virtual vector and the original vector. In addition, its amplitude is variable. The neutral point current generated by it can be used to adjust the neutral point potential. When compared with the virtual vector method, the multistage medium vector contributes to decreasing the regulation time when the modulation index is high. The vectors are rearranged to cope with the variable switching frequency of the model predictive control. Simulation and experimental results verify the validity of the proposed strategy.

• Journal of Power Electronics
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• v.17 no.1
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• pp.232-241
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• 2017

Advanced control algorithms must be used to make wind power generation truly cost effective and reliable. In this study, we develop a new and simple control scheme that employs model predictive control (MPC), which is used in permanent magnet synchronous generators and grid-connected inverters. The proposed control law is based on two points, namely, MPC-based torque-current control loop is used for the generator-side converter to reach the maximum power point of the wind turbine, and MPC-based direct power control loop is used for the grid-side converter to satisfy the grid code and help improve system stability. Moreover, a simple prediction scheme is developed for the direct-drive wind energy conversion system (WECS) to reduce the computation burden for real-time applications. A small-scale WECS laboratory prototype is built and evaluated to verify the validity of the developed control methods. Acceptable results are obtained from the real-time implementation of the proposed MPC methods for WECS.

• Journal of Korean Academy of Nursing
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• v.46 no.1
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• pp.59-68
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• 2016

Purpose: Increase in suicide rate for senior citizens which has become widespread in our society today. It is not a normal social phenomenon and is beyond the danger level. The contents of this study include Korean senior citizens' suicide related risk factors and warning signs, and the development of a simple Geriatric Suicide Risk Scale. Methods: This study is Methodological Research to verify reliability and validity of the Geriatric Suicide Risk Scale according to the tool development process suggested by Devellis (2012). Results: For predictive validity assessment, high suicide screening accuracy was showed with an Area under the ROC curve (AUC) of .93. For the optimal cutoff point of 11, sensitivity was 93.9%, and specificity, 75.7% which are excellence levels. Cross validity for assessment of generalization possibility showed the Area under the ROC curve (AUC) as .82 and in case of a cutoff point of 11, sensitivity was 73.7%, and specificity, 65.9%. Conclusion: When it comes to practical nursing, it is significant that the Korean Geriatric Suicide Risk Scale has high reliability and validity through adequate tool development and the tool assessment step to select degree of suicide risk of senior citizens. Also, it can be easily applied and does not take a long time to administer. Further, it can be used by health care personnel or the general public.

• Proceedings of the Korean Society for Cognitive Science Conference
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• 2005.05a
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• pp.9-13
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• 2005

A comprehension-based computational model of pilot action planning called ADAPT is presented to model pilot performance in a flight simulation context. Individual pilots were asked to execute a series of flight maneuvers using a flight simulator, and their eye-scanning, control movements, and flight performance were recorded in a time-synched database. Computational models of each of the 25 individual pilots were constructed, and the individual models simulated execution of the same flight maneuvers performed by human pilots. The time-synched eye-scanning, control movements, and flight performance of individual pilots and their respective models were compared to test ADAPT's predictive validity.

• Proceedings of the KIPE Conference
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• 2001.12a
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• pp.198-203
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• 2001

In this paper, a new predictive control algorithm considering the parameters of series active filter has been proposed to improve the performance. By using the proposed control scheme, the current ripple drastically reduced and an improved steady state performance can be obtained. The proposed method has another advantage in the size. and cost by excluding additional passive fitters. The validity of the proposed method will be proved by the computer simulation.

• Journal of Industrial Technology
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• v.22 no.B
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• pp.125-132
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• 2002

In this paper, a high performance current control strategy for a Brushless DC Motor is presented. The proposed strategy is based on the ramp comparison PI current control with the predictive voltage compensation. The proposed strategy is compared with the hysteresis current control strategy. The proposed method can improve the current waveforms, and it can reduce the torque ripples. So the proposed strategy is suitable to a high performance current control strategy for a Brushless DC Motor. The simulation and experimental results for a laboratory Brushless DC motor drive system confirm the validity of the proposed strategy.

• Journal of the Korean Data and Information Science Society
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• v.24 no.6
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• pp.1455-1464
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• 2013

This paper develops maximum likelihood estimators (MLEs) of unknown parameters in an exponentiated half-logistic distribution based on a progressively type-II censored sample. We obtain approximate confidence intervals for the MLEs by using asymptotic variance and covariance matrices. Using importance sampling, we obtain Bayes estimators and corresponding credible intervals with the highest posterior density and Bayes predictive intervals for unknown parameters based on progressively type-II censored data from an exponentiated half logistic distribution. For illustration purposes, we examine the validity of the proposed estimation method by using real and simulated data.

• Journal of the Korea Society of Computer and Information
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• v.20 no.9
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• pp.11-20
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• 2015

In order to prevent the elderly people from committing suicide attempts, it is necessary to verify attributes that affect the suicide attempts. It is noted that previous studies have focused on qualitative approaches, and simple correlation analyses to determine the attributes related to the suicide attempts in the elderly people. However, such previous approaches had led to insufficient performance when facing with complicated data sets. In this sense, this study suggests an alternative method in which attribute selection techniques are adopted to determine more relevant attributes of the suicide attempts occurring in Korean elderly people. To verify empirical validity of our proposed method, we used Korea National Health and Nutrition Examination Survey (KNHANES) from January 2007 to December 2012. Empirical results proved that the proposed attribute selection techniques showed better predictive effectiveness; 94.4% compared to the simple statistical methods. This study proposes a way to determining the elderly suicide and preventing it to happen.

• Proceedings of the KIPE Conference
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• 2019.11a
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• pp.180-181
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• 2019

This paper proposes a method for improving the power quality of PMSG-based wind energy conversion system based on model predictive control in DC Microgrid. The MPC has a fast dynamic response. However, a large torque ripple deteriorating power quality is generated by a large and fixed switching period. On the other hand, the proposed method improves the power quality by setting the sampling time having zero torque error. The validity of the proposed method is verified through PSIM simulation.

• Journal of Power Electronics
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• v.11 no.5
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• pp.751-758
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• 2011

This paper presents an effective robust predictive control scheme for the active power filter (APF) using a smith-predictor based current regulator, which show superior features when compared to proportional-integral (PI) controllers in terms of an enhanced closed-loop bandwidth and an improved current tracking accuracy. A moving average filter (MAF) is implemented using a field programmable gate array (FPGA) for signal pre-processing to eliminate the switching ripple contamination. An adaptive linear neural network (ADALINE) is used for individual harmonic estimation to achieve selective compensation purpose. The effectiveness and validity of the devised control algorithm are confirmed by extensive simulation and experimental results.