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AC TO AC Direct Voltage Conversion Using A Solid State Transformer
Um, Keehong The Institute of Internet 2013 International Journal of Internet, Broadcasting an Vol.5 No.1
In this paper, we present an intelligent digital controller circuit which can be applied to automatic voltage regulation. The proposed solid state transformer with Pspice simulation model shows that our approach is very efficient and produces the desirable output. It is comparable to an ordinary magnetic coupled autotransformer.
Designing Piezoelectric Audio Systems Using Polymer Polyvinylidene Fluoride
Um, Keehong,Lee, Dong-Soo,Pinthong, Chairat The Institute of Internet 2014 International Journal of Internet, Broadcasting an Vol.6 No.1
We develop a method to fabricate a flexible thin film audio systems using polyvinylidene fluoride(PVDF). The system we designed showed the properties of increased flexibility, transparency, and sound pressure levels. As an input port of two terminals, transparent oxide thin film with a low resistivity is adopted. In order to provide dielectric insulation, a transparent insulating oxide thin film is coated to obtain double-layered structure. In the range of visible light, the output from the output of the system showed a increased and improved sound pressure level. The piezoelectric polymer film of PVDF is used to produce mechanical vibration due to the applied electrical voltage signal. An analog electric voltage signal is transformed into sound waves in the audio system.
Designing Flexible Thin Film Audio Systems Utilizing Polyvinylidene Fluoride
Um, Keehong,Lee, Dong-Soo,Pinthong, Chairat The Institute of Internet 2013 Journal of Advanced Smart Convergence Vol.2 No.2
In this paper, we develop a method to design a flexible thin film audio systems utilizing Polyvinylidene fluoride. The system we designed showed the properties of increased transparency and sound pressure levels. As an input terminal transparent oxide thin film is adopted. In order to provide dielectric insulation, a transparent insulating oxide thin film is coated to obtain double -layered structure. In the range of visible light, the output from the output of the system showed an increased and improved sound pressure level. The piezoelectric polymer film of polyvinylidene fluoride (PVDF) is used to produce mechanical vibration due to the applied electrical voltage signal. An analog electric voltage signal is transformed into sound waves in the audio system.
Developing two Dimensional Film Speaker using Piezoelectric Materials
Um, Keehong,Lee, Dong-Soo The Institute of Internet 2012 International Journal of Internet, Broadcasting an Vol.4 No.1
A speaker is a system which produces sound through electromechanical operations. It transforms electronic signals into audible sound signals. Almost all speakers are three dimensional. These days, many mobile electronic devices such as mobile electronic devices have become smaller and thinner. A problem with this miniaturization, however, is that the volume of speakers has also decreased. In contrast to conventional three dimensional speakers, we have invented a new type of two dimensional flexible speaker by utilizing the reverse piezoelectric effect.
Derivation of Zeros from Externally-loaded Feed-forward Element of Filter Network
Um, Keehong,Yoo, Sooyeup,Pinthong, Chairat The Institute of Internet 2014 International Journal of Internet, Broadcasting an Vol.6 No.1
We present a mathematical method for calculation of transmission zero locations, determining a filtering characteristics of two-port systems. By adjusting element values based on the zero locations, the frequency-selectivity is characterized. The characteristic polynomial of ladder networks in externally-loaded feed-forward systems is considered by adopting chain matrices for subsystems. This method can be extended to other types of lumped systems with cross-coupled sections. We find out the zeros by solving characteristics polynomials of closed-form expressions in terms of Laplace impedances of elements. The pairs of complex zeros are shown to be solely from the cross-coupled portion of the system.
Pantograph and Stagger Inspection Using Image Processing Technique
HyungJun Kim,Keehong Um 한국멀티미디어학회 2009 한국멀티미디어학회 국제학술대회 Vol.2009 No.-
We present an image processing technique for monitoring the interaction between the pantograph and the catenary system of the Korean TIX (tilting train express) train. Due to the displacement of the contact point with respect to the reference position, an image processing analysis of each frame is performed in order to detect stagger of trolley wire automatically. The proposed approach is very efficient and produces desirable output data.
유수엽(SooYeub Yoo),엄기홍(Keehong UM),김형준,Harry Kim 한국조명·전기설비학회 2009 한국조명·전기설비학회 학술대회논문집 Vol.2009 No.5월
This paper is a report of designing for high efficient LED lights driver. The main purpose of driver designing is meet the requirement the high efficient energy regulation for light of Korea. To meet the regulation the high efficient, the circuit adapted wide range resonant power supply and current regulate circuit to adjust LED current. This product archived excellent performance as well as reliable operation.