• The Transactions of the Korean Institute of Electrical Engineers A
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• v.55 no.3
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• pp.102-108
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• 2006

This paper proposes a 36-pulse back-to-back voltage source converter using four sets of 12-pulse bridges with pulse-Interleaving auxiliary circuit. The proposed back-to-back voltage source converter has an independent control capability of active power and reactive power at the at connection point. The principle of increasing the number of pulses was analyzed using theoretical approach. The operational feasibility of proposed system was verified through computer simulations with PSCAD/EMTDC software. The proposed back-to-back converter can be widely used for the HVDC and FACTS devices.

• Journal of Power Electronics
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• v.10 no.2
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• pp.125-131
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• 2010

Switched-resonator converters are a new family of soft switching DC-DC converters where the energy is transferred via a resonator. This paper introduces some isolated topologies of this family. The achieved advantages include, load independent soft-switching, self short-circuit protection, and optimization capability due to topology variety. Compared to conventional series-resonant converters, outstanding advantages such as a smaller fewer number of switches and diodes, a smaller transformer, and lower current stresses are achieved. A general synthesis scheme, functional topologies, and essential relations are included. Experimental results from a laboratory prototype confirm the presented theoretical analysis.

• Proceedings of the KIEE Conference
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• summer
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• pp.1245-1247
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• 2004

This paper considers the design and implementation of novel technique of speed estimation and control for IPMSM using hybrid intelligent control. The hybrid combination of neural network and adaptive fuzzy control will produce a powerful representation flexibility and numerical processing capability. Also, this paper is proposed speed control of IPMSM using adaptive neural network fuzzy(A-NNF) and estimation of speed using artificial neural network(ANN) controller. This paper is proposed the theoretical analysis as well as the simulation results to verify the effectiveness of the new hybrid intelligent control.

• 한국연소학회:학술대회논문집
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• 2013.06a
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• pp.117-119
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• 2013

Combustion stability margin of a model gas turbine has been assessed by utilizing damping ratios of measured dynamic pressure data. It is known that acoustic oscillations in combustion chambers can be described as a superposition of nonlinearly interacting oscillators. Based on this theoretical background, CSMA (Combustion Stability Margin Assessment) code has been developed. The code has been employed into a model gas turbine combustion experiment, focused on the combustion instability, to show its capability to determine the damping ratio of measured dynamic pressure and further to assess combustion stability margin of the experiment, and turned out that the code works well.

• Proceedings of the Korea Technology Innovation Society Conference
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• 1999.11c
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• pp.557-575
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• 1999

The task evaluating science and technology is becoming more important in every country trying to develop and improve overall national R&D capability in an effort to sustain national prosperity and public welfare. However, the way in which evaluation organisation is approached in each country may differ from nation to nation reflecting national R&D systems and S&T policies as well as the specific roles of scientists and policy- makers at various levels. Over the past two decades or so, Korean evaluation system has been transplanted form the West and they modified, In addition, Korea borrowed elements from the Japanese. Whether such systems have been well rooted in our specific circumstances is a critical question. In this context, it would be meaningful to diagnoses the current Korean evaluation system and also makes some suggestions for improving this system. For this purpose, this paper also attempts to approach to the theoretical aspects of evaluation as a starting-point.

• Nuclear Engineering and Technology
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• v.50 no.6
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• pp.849-853
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• 2018

Mechanistic calculations for wet scrubbing of aerosol/vapor from gas bubble rising in liquid pool are essential to safety of sodium-cooled fast reactor. Hence, scrubbing of volatile fission product from mixed gas bubble rising in sodium pool is presented in this study. To understand this phenomenon, a theoretical model has been setup based on classical theories of aerosol/vapor removal from bubble rising through liquid pools. The model simulates pool scrubbing of sodium iodide aerosol and cesium vapor from a rising mixed gas bubble containing xenon as the inert species. The scrubbing of aerosol and vapor are modeled based on deposition mechanisms and Fick's law of diffusion, respectively. Studies were performed to determine the effect of various key parameters on wet scrubbing. It is observed that for higher vapor diffusion coefficient in gas bubble, the scrubbing efficiency is higher. For aerosols, the cut-off size above which the scrubbing efficiency becomes significant was also determined. The study evaluates the retention capability of liquid sodium used in sodium-cooled fast reactor for its safe operation.

• Korea journal of population studies
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• v.8 no.2
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• pp.68-78
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• 1985

It is well recognized that, in most developing countries, rapid population growth has been a serious problem. And there is a growing tendency to regard the problem as a political issue in these coun-tries. So far, many developing countries have formulated and implemented population policies aiming at an reduction of such population growth. This study attempts, in policy perspective, to examine theoretically the process and determinants of population policy making and implementation in those developing countries. In doing this, it gives emphasis on explaining population policy determinants and therefore, deals with (1) decision makers' perceptions and attitudes, (2) governmental structure and capability, (3) mass fertiliry behavior, and (4) foreign aid agencies' role.

• Journal of Power Electronics
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• v.19 no.2
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• pp.602-611
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• 2019

The major drawbacks of magnetic resonant coupled wireless power transfer (WPT) to the embedded sensors on spindles are transmission instability and low efficiency of the transmission. This paper proposes a novel double-loop coil design for wirelessly charging embedded sensors. Theoretical and finite-element analyses show that the proposed coil has good transmission performance. In addition, the power transmission capability of the double-loop coil can be improved by reducing the radius difference and width difference of the transmitter and receiver. It has been demonstrated by analysis and practical experiments that a magnetic resonant coupled WPT system using the double-loop coil can provide a stable and efficient power transmission to embedded sensors.

• Journal of Power Electronics
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• v.19 no.3
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• pp.803-814
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• 2019

This paper proposes a three-phase current balancing strategy in a power transmission system employing distributed static series compensators (DSSCs). With the proposed variable quadrature voltage injection method, the DSSC emulates either an inductive or a capacitive impedance into the transmission line, and the magnitudes of the phase currents are balanced. Hence, the phase imbalances in the power transmission system are significantly reduced. As a result, the power transfer capability of the transmission lines can be improved. The operational principle of the DSSCs, the hardware structure and the control algorithm are described in detail. Finally, the theoretical analyses and the proposed strategy are experimentally verified through a scaled down transmission system with DSSC prototypes.

• International Journal of Computer Science & Network Security
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• v.21 no.4
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• pp.223-228
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• 2021

As a consequence of sudden outbreak of COVID-19 pandemic worldwide, educational institutes around the globe are forced to switch from traditional learning systems to e-learning systems. This has led to a variety of technology-driven pedagogies in e-teaching as well as e-learning. In order to take the best advantage, an appropriate understanding of the cognitive capability is of prime importance. This paper presents an intelligent cognitive maturity recognition system for confidence-based e-learning. We gather the data from actual test environment by involving a number of students and academicians to act as experts. Then a Genetic Programming based simulation and modeling is applied to generate a generalized classifier in the form of a mathematical expression. The simulation is derived towards an optimal space by carefully designed fitness function and assigning a range to each of the class labels. Experimental results validate that the proposed method yields comparative and superior results which makes it feasible to be used in real world scenarios.