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Uyun S.,State Islamic University of Yogyakarta
Journal of Theoretical and Applied Information Technology

Image thresholding is one of image processing techniques to help analyze the next phase. Consequently, choosing a precise method in this step is quite-essential. Image blurs and bad illumination are common constraints that often influence the effectiveness of the thresholding method. Fuzzy sets is one among other perceptions in scoring an image. Thus, various thresholding fuzzy techniques have been developed to eliminate those constraints. This paper proposes the improvement of multilevel thresholding techniques by using type II fuzzy sets with the function of gaussian membership to access some objects at mammogram to get fibroglandular tissue areas. The result shows that the proposed technique has a very good achievement with the average score with misclassification error parameter of 97.86%. This proves that the proposed algorithm are able to function well to the image with low contrast level and high unclearness level. © 2005 - 2015 JATIT & LLS. All rights reserved. Source

Rahmayanti M.,State Islamic University of Yogyakarta | Santosa S.J.,Gadjah Mada University | Sutarno,Gadjah Mada University
International Journal of ChemTech Research

Gallic acid-modified magnetite particles (Mag-GA) were synthesized via reverse coprecipitation method. The obtained Mag-GA were characterized by Fourier Transform Infrared spectroscopy and X-Ray diffraction. FTIR characterization for Mag-HA after modification indicated the presence of specific absorption bands for functional groups of humic acid and Fe-O bonds, though with lower intensity than before modification. The XRD patterns showed that the crystalinity of magnetite before modification were higher than after modification with gallic acid. The mechanism of synthesis was assumed to occur through electrostatic bonding between the surface of magnetite and gallic acid. The Mag-GA particles were applied for AuCl4-adsorption and results showed that the optimum adsorption of [AuCl4]-onto Mag-GA was found at pH 3. The mechanism of gold recovery using Mag-GA particles takes place through the formation of hydrogen bonding followed by reduction of trivalent gold ions to metallic gold, which is accompanied by simultaneous oxidization of the hydroxyl groups of gallic acid. This assumption was supported by FTIR spectra, XRD chromatogram and photo-optical microscope that showed the presence of metallic gold on Mag-GA after adsorption. © 2016 Sphinx Knowledge House. All right reserved. Source

Fajriati I.,State Islamic University of Yogyakarta | Mudasir,Gadjah Mada University | Wahyuni E.T.,Gadjah Mada University
Indonesian Journal of Chemistry

The photocatalytic decolorization of methyl orange (MO) by TiO2-chitosan nanocomposite has been studied. This study was started by synthesizing TiO2-chitosan nanocomposites using sol-gel method with various concentrations of Titanium(IV) isopropoxide (TTIP) as the TiO2precursor. The structure, surface morphology, thermal and optical property of TiO2-chitosan nanocomposite were characterized by X-ray diffraction (XRD), fourier transform infra red (FTIR) spectroscopy, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and diffuse reflectance ultra violet (DRUV) spectroscopy. The photocatalytic activity of TiO2-chitosan nanocomposite was evaluated by photocatalytic decolorization of methyl orange as a model pollutant. The results indicate that the particle size of TiO2increases with increasing of the concentration of TTIP, in which TiO2with smallest particle size exhibit the highest photocatalytic activity. The highest photocatalytic decolorization was obtained at 5 h of contact time, initial concentration of MO at 20 ppm and at solution pH of 4. Using these conditions, over 90% of MO was able to be decolorized using 0.02 g of TiO2-chitosan nanocomposite under UV light irradiation. The TiO2-chitosan nanocomposite could be reused, which meant that the TiO2-chitosan nanocomposites can be developed as an effective and economical photocatalyst to decolorize or treat dye in wastewater. © 2014 Gadjah Mada University. All Rights reserved. Source

Nafisah S.,Gadjah Mada University | Nafisah S.,State Islamic University of Yogyakarta | Wahyunggoro O.,Gadjah Mada University | Nugroho L.E.,Gadjah Mada University
International Journal on Advanced Science, Engineering and Information Technology

Speech recognition applications are becoming more and more useful nowadays. Before this technology is applied, the first step is test the system to measure the reliability of system. The reliability of system can be measured using accuracy to recognize the speaker such as speaker identity or gender. This paper introduces the stochastic model based on mel-frequencies to identify the gender of speaker in a noisy environment. The Euclidean minimum distance and back propagation neural networks were used to create a model to recognize the gender from his/her speech signal based on formant and pitch of Mel-frequencies. The system uses threshold technique as identification tool. By using this threshold value, the proposed method can identifies the gender of speaker up to 94.11% and the average of processing duration is 15.47 msec. The implementation result shows a good performance of the proposed technique in gender classification based on speech signal in a noisy environment. Source

Dewi A.S.,State Islamic University of Yogyakarta
Internetworking Indonesia Journal

This article aims to describe the application of local e-Government by the Government of Terong, Bantul District, Yogyakarta Province, Indonesia. The method used in the research is case study. This research shows that the government of Terong has succeed to develop community based e-government model, namely Sistem Informasi Desa (SID/Village Information System). This model is a result of media convergence which already exist, such as community radio, community news letter and citizens forum. Besides media convergence, involvement of all elements in Terong played important role in the development of SID. Strong leadership and good will from local government also contributed to the process of SID. The result of this effort is better public service by local government. These findings conclude that bureaucratic reform can occur with the help of ICT. Source

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