Cheongyang Provincial College

Cheongyang, South Korea

Cheongyang Provincial College

Cheongyang, South Korea

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Park Y.-S.,Chungnam National University | Koo M.-M.,Chungnam National University | Jang S.-M.,Chungnam National University | Choi J.-Y.,Chungnam National University | You D.-J.,Cheongyang Provincial College
IEEE Transactions on Magnetics | Year: 2014

This paper analyzes the dynamic characteristics of interior permanent magnet synchronous motor (IPMSM), taking in to account the outer disturbance to a motor system. Based on the analyzed results from electromagnetic field characteristic analysis, the equivalent circuit parameters are derived, and the modeling of both IPMSM and controller system is also performed to predict its operating characteristics. In particular, in our simulation, the dynamic characteristics according to inductance variation by an outer disturbance are specifically analyzed, and all the simulation results are experimentally validated showing well corresponded results. © 2014 IEEE.


Park Y.-S.,Chungnam National University | Koo M.-M.,Chungnam National University | Jang S.-M.,Chungnam National University | Choi J.-Y.,Chungnam National University | You D.-J.,Cheongyang Provincial College
IEEE Transactions on Energy Conversion | Year: 2015

This paper addresses comparative investigation on the permanent magnet (PM) wind power generators' performance considering PM flux directions while generated electrical energy is being stored through a mechanical energy storage system (MESS). Radial- and axial-flux PM generators are dealt with, and since their equivalent circuit parameters are almost identical, their comparison can be reasonable. During the energy conversion through the MESS, since a power converter is required, the phase current of each generator contains harmonic components due to diode rectifier with high influence on the generators' performance. In this study, the electromagnetic characteristics of each generator are analyzed based on the measured current to consider the influence of those harmonics, and their performance evaluation is also performed by experiment. © 1986-2012 IEEE.


Jang S.-M.,Chungnam National University | Park Y.-S.,Chungnam National University | Sung S.-Y.,Chungnam National University | Lee K.-B.,Chungnam National University | And 2 more authors.
IEEE Transactions on Magnetics | Year: 2011

This paper deals with the dynamic characteristics of a linear induction motor (LIM) in terms of acceleration times and jerk conditions. We employed Matlab Simulink for conducting simulations of the dynamic modeling of LIM operated by a space vector pulse width modulation inverter. From the simulation results, the maximum load conditions and minimum acceleration times to guarantee passengers' safety were determined. Further, the electromagnetic field theory was employed to derive equivalent circuit parameters, and the results were validated by the finite element method. The analysis model was applied to a magnetic levitation vehicle for providing electromagnetic propulsion force, and its dynamic characteristics were analyzed to predict its operating performance; moreover, experimental results were employed to demonstrate the validity. We believe that the proposed prediction technique for the operating characteristics of LIMs can contribute to improving passengers' safety and riding quality. © 2011 IEEE.


Park Y.-S.,Chungnam National University | Jang S.-M.,Chungnam National University | Choi J.-Y.,Chungnam National University | Choi J.-H.,Chungnam National University | You D.-J.,Cheongyang Provincial College
Proceedings of the IEEE International Conference on Industrial Technology | Year: 2013

This paper deals with the influence of AC-DC-DC converter on permanent magnet (PM) wind power generators. Differently from AC load conditions, since the phase current in PM generators with the converter contains harmonic components, their influence on generators' performance is investigated. In particular, in this paper, two PM generator types, radial flux PM generator and axial flux PM generator, are considered for the comparative investigation. The generators are connected to a mechanical energy storage system consisted of a permanent magnet synchronous motor with a heavy wheel, and the generator performance characteristics are dealt with while the mechanical energy storage system is being operated. © 2013 IEEE.


Min J.-H.,Daejeon University | Nam Y.-G.,Chungnam Agriculture Research and Extension Service | Ju J.-I.,Chungnam Agriculture Research and Extension Service | Jung J.-H.,Cheongyang Provincial College | And 2 more authors.
Korean Journal of Microbiology and Biotechnology | Year: 2012

In this study, we investigated the microbial flora changes in Gugija-Liriope tuber Makgeolli during fermentation and storage periods. We brewed Gugija-Liriope tuber Makgeolli for a week through two-stage fermentations and stored the fermentation broth for a month at 4°C or 2O°C. We collected the samples periodically and analyzed microbial flora changes using viable cell counts and PCR-denaturing gradient gel electrophoresis (DGGE). Yeast viable cells were seen to have decreased to 13% of pre-storage levels after storage for 15 days at 20°C; however significant changes were not observed during storage at 4°C. Prolongation of storage time dramatically decreased the availability of viable cells. Yeast viable cell numbers had decreased to 38% of pre-storage levels at 4°C and 4.8% at 20°C after storage for 30 days. The results of the DGGE profile for yeast showed that Saccharomyces cerevisiae and Saccharomyces sp. were the predominant strains at the beginning of fermentation and throughout the whole period of storage. Viable cell counts for total bacteria had decreased to 36% of pre-storage levels after storage for 15 days but did not significantly change for the full 30 days of storage at 4°C. Similarly, viable cell counts for bacteria had decreased to 5% while viable cell numbers did not significantly change for the full 30 days at 20°C. Viable cell counts for lactic acid bacteria were performed and the results were similar to those for total bacteria. The results of the DGGE profile for bacteria showed that Weissella cibaria was the predominant strain at the beginning of fermentation. However it had disappeared by the end of fermentation, and Lactobacillus fermentum and Pediococcus acidilactici became the predominant species during storage. © The Korean Society for Microbiology and Biotechnology.


Park S.-W.,Hanbat National University | Jang C.-H.,Hanbat National University | Baek K.-R.,Cheongyang Provincial College | Yang J.-K.,Cheongyang Provincial College
Energy | Year: 2012

Preprocessing of woody biomass was performed with torrefaction and low-temperature carbonization. In this study, the pretreated samples have been used to evaluate the energy yield and fuel characteristics. The combustion profiles of the torrefied sample and the low-temperature carbonized sample blended with coal were examined in order to analyze the characteristics of co-combustion. Energy yields of 80-98% in torrefied samples and 46-63% in low-temperature carbonized samples were observed. It was found that in the low-temperature carbonization zone, the coal band moved toward that of coal. The number of differential thermogravimetric peaks decreased from two to one with an increase in the thermal-treatment temperature. In the case of samples blended with coal and low-temperature carbonized samples at 350 °C, it has been confirmed that the activation energy and all index parameters decreased as the blend ratio increased. It was confirmed that as a result, the combustion rate (d. α/d. t) became higher owing to an increased value of the constant (k), which represents the reaction rate. However, in the case of the sample torrefied at 275 °C, it was I confirmed that the combustion rate was not the same, according to the co-combustion ratio, because of an opposite tendency shown in the devolatilization and char combustion stages. © 2012 Elsevier Ltd.

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