• Journal of Ocean Engineering and Technology
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• v.24 no.5
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• pp.48-54
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• 2010

The analysis of the seismic risk of an offshore structure with a control device is presented. First, a probability density function was developed to represent seismic hazard, and seismic fragility under artificial earthquake conditions was determined. Fragility curves for an offshore structure with both passive and active control devices were determined. Displacement criteria were set to evaluate the performance of the structure. Based on numerical analysis, the seismic risk to the structure was considerably reduced when the structure had a seismic control device. The seismic risk to the actively controlled structure was decreased by 80% compared to the uncontrolled case. Reasonable performance evaluations of offshore structure with control devices can be conducted through risk analysis.

• Journal of Electrical Engineering and Technology
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• v.7 no.1
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• pp.34-45
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• 2012

In the present paper, the mover speed control of a linear induction motor (LIM) using a sliding mode control design is proposed, considering the end effects. First, the indirect field-oriented control LIM is derived, considering the end effects. The sliding mode control design is then investigated to achieve speed- and flux-tracking under load thrust force disturbance. The numerical simulation results of the proposed scheme present good performances in comparison to that of the classical sliding mode control.

• Atmosphere
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• v.24 no.1
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• pp.77-87
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• 2014

The radar reflectivity is significantly affected by ground clutter, beam blockage, anomalous propagation (AP), birds, insects, chaff, etc. The quality of radar reflectivity is very important in quantitative precipitation estimation. Therefore, Weather Radar Center (WRC) of Korea Meteorological Administration (KMA) employed two quality control algorithms: 1) Open Radar Product Generator (ORPG) and 2) fuzzy quality control algorithm to improve quality of radar reflectivity. In this study, an occurrence of AP echoes and the performance of both quality control algorithms are investigated. Consequently, AP echoes frequently occur during the spring and fall seasons. Moreover, while the ORPG QC algorithm has the merit of removing non-precipitation echoes, such as AP echoes, it also removes weak rain echoes and snow echoes. In contrast, the fuzzy QC algorithm has the advantage of preserving snow echoes and weak rain echoes, but it eliminates the partial area of the contaminated echo, including the AP echoes.

• Nuclear Engineering and Technology
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• v.42 no.4
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• pp.460-467
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• 2010

In this study, the parameters of the feedwater control system (FWCS) of the OPR1000 type nuclear power plant (NPP) are optimized by response surface methodology (RSM) in order to acquire better level control performance from the FWCS. The objective of the optimization is to minimize the steam generator (SG) water level deviation from the reference level during transients. The objective functions for this optimization are relationships between the SG level deviation and the parameters of the FWCS. However, in this case of FWCS parameter optimization, the objective functions are not available in the form of analytic equations and the responses (the SG level at plant transients) to inputs (FWCS parameters) can be evaluated by computer simulations only. Classical optimization methods cannot be used because the objective function value cannot be calculated directely. Therefore, the simulation optimization methodology is used and the RSM is adopted as the simulation optimization algorithm. Objective functions are evaluated with several typical transients in NPPs using a system simulation computer code that has been utilized for the system performance analysis of actual NPPs. The results show that the optimized parameters have better SG level control performance. The degree of the SG level deviation from the reference level during transients is minimized and consequently the control performance of the FWCS is remarkably improved.

• The Journal of the Korea Contents Association
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• v.8 no.9
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• pp.259-273
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• 2008

This study aims to identify of customer features control the effect on revisit intention and switching intention. The statistical techniques used for this empirical analysis are frequency analysis, technology analysis, reliability analysis, factor analysis, confirmatory factor analysis along with path analysis and moderate regression analysis, which are based on structural model From the effect that customer features control the effect on switching barrier by switching intention, travel agencies has a control effect on 'financial switching costs' and 'relational switching costs', and airlines show they have control effect on 'relational switching costs.' In diversity pursuit factors, 'financial switching costs' and 'attractiveness of alternatives' have a meaningful control effect for travel agencies customers, while 'procedural switching costs' for airlines customers. In the analysis result of the effect that customer features control the effect on revisit intention by switching intention, 'percept' and 'diversity pursuit' have a meaningful control effect in travel agencies customers and airlines one, respectively.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.6 s.99
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• pp.652-659
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• 2005

In this paper, seismic qualification analysis for the Plant control Panel is carried out to confirm the structural integrity under the seismic conditions represented by required response spectra(RRS). The finite element method(FEM) is used for the analysis and a mode combination method is adopted to obtain a more reliable spectrum analysis results. In addition, the experimental analysis is performed to compare the reliability of the analytical results. The analysis results shows that the plant control panel system is designed to have the dynamic rigidity with no resonance frequency below 33 Hz. The analytically calculated maximum stress of the plant control panel system is $36\%$ of the field strength of material, thus it can be shown that the system has a stable structure for the seismic load.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.577-582
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• 2000

The pseudo-volume control method is developed for the failure analysis of RC slabs, by adding pressure node into layered shell element utilizing in-plane constitutive models of reinforced concrete and layered formulation. For the failure analysis of RC slabs n this paper, geometric nonliearity is also considered in the analysis. The validity of the pseudo-volume control method is verified by comparing analysis results and existing experimental results.

• Korean Journal of Human Ecology
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• v.13 no.6
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• pp.833-845
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• 2004

This study examines different individual and environmental factors that affect children's self-control. For an analysis, locus of control, perceived competence, and achievement motivation were all included in individual variables. For family variables, mothers' parenting and patents' marriage conflict were examined. For classroom psycho-social environment, teacher support, peer relationship, class involvement, and teachers' supervision were used. The sample consisted of 548 fifth and sixth grade children. Statistics and methods used for the data analysis were Cronbach's alpha, frequency, percentage, Pearson's correlation, and Hierarchical Regression. Several major results were found from the analysis: First, locus of control, perceived competence, and achievement motivation had a positive correlation with children's self-control. Second, mothers' affective parenting had a positive correlation with children's self-control. However, mothers' controlling parenting and parents' marriage conflict had a negative correlation with it. Third, teacher support, peer relationship, and class involvement had a positive correlation with children's self-control. In addition, teacher supervision had a positive correlation with girls' self-control. Fourth, class involvement, locus of control, and academic competence were important variables predicting boys' self-control. On the other hand, Class involvement, achievement motivation, academic competence, teacher's supervision, and mothers' controlling parenting were important variables predicting girl's self-control.

• Journal of Electrical Engineering and Technology
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• v.12 no.2
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• pp.761-768
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• 2017

This paper deals with the performance analysis of three phase induction motor considering its stator side faults and operating thermal limits. The speed control of induction motor using three phase boost converter operated by a MOSFET switch and a PI controller is demonstrated and presented in this article. IGBTs switches are used for inverter drive mechanism. The experimental result of speed control of induction motor using voltage control technique clearly shows better accuracy than conventional methods of speed control. A three phase 1HP 415V 0.78 kW 4 Pole induction motor is designed using motor solver software. Based on the parameters used in the software thermal analysis of induction motor is done and torque variation with conductor area, efficiency, output curve, losses in different parts of motor has been obtained. Also different types of faults namely under voltage, over voltage, stator imbalanced voltage, turn to turn, locked rotor bar, wrong alignment of rotor bar with respect to stator are studied and fault analysis is performed. Hence comparison is made based upon the results obtained before and after faults.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.4
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• pp.328-333
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• 2013

Since a slight malfunction of control systems in a nuclear power plant may cause huge catastrophes, such control systems usually have multiple redundancy and reliable features, and their reliability and availability should be analyzed and verified thoroughly. This paper performed the reliability analysis of the SPLC (Safety Programmable Logic Controller) that is under developed as the control systems for the next generation nuclear power plant. One of the key features of SPLC is that it has multiple redundancy modes as faults happen, which means the reliability analysis for one fixed redundant model is not enough to analyze the reliability of SPLC. With considering this reconfigurable concept, FTA (Fault Tree Analysis) was used to capture fault-relationship among sub-modules. The analysis results show that MTTF (Mean Time to Fault) of SPLC is 45,080 hours, which is a about 4.5 times longer than the regulation, 10,000 hours.