• IE interfaces
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• v.5 no.1
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• pp.25-34
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• 1992

A study to analyze and solve inherent problems of a pilot cola machine has been presented in this paper. The product considered in this study involves at least 16 variables(factors) which simultaneously affect the product performance. For this multi-variate statistical problem, we first carefully examined their relationships and selected four variables considered as the most important. We have taken Taguchi's parameter design approach, specifically the $L_8\:(2^7)$ orthogonal array, and determined the optimal levels of the selected variables through the analysis of the experimental results. Finally, we conclude this study with providing general comments drawn from the analysis and verification experiments.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.7
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• pp.1105-1110
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• 2017

Speech with various emotions degrades the performance of the speaker recognition system. In this paper, a speaker recognition method using emotional adaptation has been proposed to improve the performance of speaker recognition system using affective speech. For emotional adaptation, emotional speaker model was generated from speaker model without emotion using a small number of training affective speech and speaker adaptation method. Since it is not easy to obtain a sufficient affective speech for training from a speaker, it is very practical to use a small number of affective speeches in a real situation. The proposed method was evaluated using a Korean database containing four emotions. Experimental results show that the proposed method has better performance than conventional methods in speaker verification and speaker recognition.

• Journal of Electrical Engineering and Technology
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• v.13 no.1
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• pp.280-286
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• 2018

A sensorless active damping scheme for LCL filters in grid-connected parallel inverters for battery energy storage systems is proposed. This damping method is superior to the conventional notch filter and virtual damping methods with respect to robustness against the variation of the resonance of the filter and unnecessary additional current sensors. The theoretical analysis of the proposed damping method is explained in detail, along with the characteristic comparison to the conventional active damping methods. The performance verification of the proposed sensorless active damping method shows that its performance is comparable to that of the conventional virtual damping method, even without additional current sensors. Finally, simulation and experimental results are provided to examine the overall characteristics of the proposed method.

• Journal of the Korean Society of Safety
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• v.11 no.2
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• pp.143-149
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• 1996

We propose an Opto-Digital hybrid fingerprint Identification system based on the binary phase extraction joint transform correlator(BPEJTC) for validation and security yerification. It is shown that since the BPEJTC provides higher peak-to-sidelobe ratio than that of the conventional JTC and does not cause correlation peaks due to intra-class association, this system is well-adaptive to the multiple object environments. Experimental results show that this system has a good performance in the presence of multiple images and the variations of the same person.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.5
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• pp.485-491
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• 2013

A new passive lossless snubber for boost converter based on magnetic coupling is proposed. It is composed of a winding coupled with boost inductor, one snubber inductor, two snubber capacitor and three additional diodes. Especially, the snubber inductor can not only limit the reverse recovery current of output diode but also minimize switch turn-on losses greatly. Moreover, all of the energy stored in the snubber is transferred to the load in the manner of resonance. To confirm the validity of proposed system, theoretical analysis, design consideration, and verification of experimental results are presented.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2265-2267
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• 2005

We present detailed studies of externally applicable UHF PD sensors for a metal covered epoxy barrier with a small opening of epoxy injection-hole. The sensors were attached at the surface of injection hole of a metal covered epoxy barrier. 3-Dimensional electro magnetic simulations were performed to analyze electric-field distribution of the GIS and epoxy barrier with injection hole. Sensor structures were designed and analyzed using the 3-D EM simulator then fabricated for experimental verification. Sensor performance was measured in terms of spectral response and detected peak power. Real scale GIS and epoxy barriers were used to test and measure various aspect of performance of the sensors.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.1307-1309
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• 1996

This paper presents hybrid active noise control (HANC) systems which is based on the combination of feedforward and feedback ANC controllers. HANC systems use FIR filters and is based on primary noise regeneration principle and filtered-X LMS algorithms. HANC systems show better attenuation characteristics and residual spectrum. The order of adaptive filters used in HANC systems is lower than that of conventional feedforward and feedback ANC systems. A proposed HANC algorithm was implemented using a Taxas Instruments TMS320C31 digital signal processor for experimental verification.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.22 no.4
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• pp.93-98
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• 2014

In this study, control of oxidizer mass flow rate and verification of control system were performed for hybrid rocket thrust control application. Oxidizer flow control system consists of ball valve and stepping motor where gaseous oxygen was used for oxidizer at feeding pressure of 10, 20 and 30 bar. According to experimental results, the oxidizer mass flow rate showed a relatively linear increment as ball valve open angle increases regardless of feeding pressure. In addition, the level of the oxidizer flow rate was kept almost constant at each sequence of flow control with ball valve during the 20 seconds of operation.

• Journal of information and communication convergence engineering
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• v.11 no.2
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• pp.139-146
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• 2013

This paper proposes a new spatial filtering approach for increasing the depth-of-field (DOF) of imaging systems, which is very useful for obtaining sharp images for a wide range of axial positions of the object. Many different techniques have been reported to increase the depth of field. However the main advantage in our method is its simplicity, since we propose the use of purely absorbing beam-shaping elements, which allows a high focal depth with a minimum modification of the optical architecture. In the filter design, we have used the analogy between the axial behavior of a system with spherical aberration and the transverse impulse response of a 1D defocused system. This allowed us the design of a ring-shaded filter. Finally, experimental verification of the theoretical statements is also provided.

• Journal of Power Electronics
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• v.15 no.4
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• pp.964-973
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• 2015

This paper presents a simple approach for the selective harmonic elimination (SHE) of multilevel inverter based on the transistor-clamped H-bridge (TCHB) family. The SHE modulation is derived from the sinusoidal voltage-angle equal criteria corresponding to the optimized switching angles. The switching angles are computed offline by solving transcendental non-linear equations characterizing the harmonic contents using the Newton-Raphson method to produce an optimum stepped output. Simulation and experimental tests are conducted for verification of the analytical solutions. An Altera DE2 field-programmable gate array (FPGA) board is used as the digital controller device in order to verify the proposed SHE modulation in real-time applications. An analysis of the voltage total harmonic distortion (THD) has been obtained for multiple output voltage cases. In terms of the THD, the results showed that the higher the number of output levels, the lower the THD due to an increase number of harmonic orders being eliminated.