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29,734 Article Results

Dual-band aperture coupled antenna with harmonic suppression capability

10.12928/telkomnika.v17i1.11598
Faza Syahirah Mohd; Universiti Teknikal Malaysia Melaka (UTeM) Noor , Zahriladha; Universiti Teknikal Malaysia Melaka (UTeM) Zakaria , Herwansyah; Universiti Teknikal Malaysia Melaka (UTeM) Lago , Maizatul Alice Meor; Universiti Teknikal Malaysia Melaka (UTeM) Said
The paper presents an aperture-coupled dual-band linearly-polarized antenna with harmonic suppression capability, operating at frequency 2.45 GHz and 5.00 GHz. In purpose of improving the directivity of antenna at the operating frequency of 2.45 GHz and 5.00 GHz, a modified inverted π-shaped slot-etched patch on the lower layer of the stacked antenna is introduced alongside the 50 Ω feed line. The harmonic suppression capability is achieved by the introduction of U-slot and asymmetrical left-right-handed stub at the transmission feed line, suppressing unwanted harmonic signals from 6.00 GHz up to 10.00 GHz. The final design of the antenna has produced very good reflection coefficient of -18.87 dB at 2.45 GHz and -19.57 dB at 5.00 GHz with third and higher order harmonic suppression up to -4 dB.
Volume: 17
Issue: 1
Page: 60-67
Publish at: 2019-02-01

Biometric identification using augmented database

10.12928/telkomnika.v17i1.11713
Regina; Universitas Mercu Buana Lionnie , Ellisa; Universitas Mercu Buana Agustina , Wahju; Universitas Mercu Buana Sediono , Mudrik; Universitas Mercu Buana Alaydrus
Androgenic hair pattern is one of the newest soft biometric trait that can be used to identify criminals when their faces are covered in the evidences of criminal investigation. In real-life situation, sometimes the available evidence is limited thus creating problems for authorities to identify criminal based on the limited data. This research developed the recognition system to identify individuals based on their androgenic hair pattern in a limited data situation in such a way that the limited images were expanded by the augmentation process. There were 50 images studied and expanded into 2.000 images from the augmentation process of rotating, reflecting, adjusting color and intensity. Furthermore, the effect of human skin color extraction was investigated by employing HSV and YCbCr color spaces. The scale-space hierarchy was built among the images with Gaussian function and produced 70% recognition precision that was around more than 2 times higher compared to system of recognition with only limited data.
Volume: 17
Issue: 1
Page: 103-109
Publish at: 2019-02-01

A gamification framework to enhance students’ intrinsic motivation on MOOC

10.12928/telkomnika.v17i1.10090
Rujianto Eko; STMIK AMIKOM Purwokerto Saputro , Sazilah; Universiti Teknikal Malaysia Melaka Salam , Mohd. Hafiz; Universiti Teknikal Malaysia Melaka Zakaria , Toni; STMIK AMIKOM Purwokerto Anwar
Technological development supports the distribution of education to various parts of the world through online education. One of the learning media that supports the distribution of learning is the Massive Open Online Course (MOOC). However, MOOC has a low number of students who complete the course. Therefore, this research proposes a "gamification framework" through studies and various approaches in the field of games, intrinsic motivation elements, social learning, and interactive learning environments to overcome the low motivation of students. The proposed framework has been evaluated through validation by experts. The results found that the framework fulfilled the rules and suitability of the instruments and game elements used to increase the intrinsic motivation of students in online learning. Although there are some changes in the function and type of game elements used. For further research, the framework will be used as a guideline to build the Gamified MOOC Platform.
Volume: 17
Issue: 1
Page: 170-178
Publish at: 2019-02-01

Design of compact multi-mode microstrip resonator filters for dual-band application

10.11591/ijeecs.v13.i2.pp696-701
Nurshamimi Rosli , Siti Aminah Md Akhir , Siti Zuraidah Ibrahim , Nur Baya Mohd Hashim , Nurehansafwanah Khalid
This paper presents the design of compact multi-mode microstrip resonator filters for dual-band application. The design is simulated using Advanced Design System (ADS) 2016 software. The benefit of the proposed filter is found to have a dual-mode frequency, where the odd-mode resonant frequency is the fundamental frequency represented by the length of the resonator while the even-mode resonant frequency is represented by the length of the stub. To validate the design, a prototype is fabricated on Rogers RO4003C substrate and measured using PNA Network Analyzer.
Volume: 13
Issue: 2
Page: 696-701
Publish at: 2019-02-01

A compact high-gain parasitic patch antenna with electronic beam-switching

10.11591/ijeecs.v13.i2.pp551-555
D. Subramaniam , M. Jusoh , T. Sabapathy , M. N. Osman , M. R. Kamarudin , R. R. Othman , M. R. Awal
A high beam steering antenna using HPND PIN Diode is proposed with a capability of steering its beam into three different directions -40 º, 0º and 40 º with respective switching condition. The reconfigurable parasitic antenna consists of a driven element and two reconfigurable parasitic elements, is designed with operating range of 9.5GHz. The parasitic elements act as reflectors or director depending on the switching conditions. Both parasitic elements are connected to ground plane via shorting pins. The reconfiguration is controlled by the two HPND PIN Diode switch that embeds to the parasitic element. An average gain value of 8dBi is achieved at all reconfiguration scenarios. All the simulated design has been carried out using CST software.
Volume: 13
Issue: 2
Page: 551-555
Publish at: 2019-02-01

Threshold voltage roll-off for sub-10 nm asymmetric double gate MOSFET

10.11591/ijece.v9i1.pp163-169
Hakkee Jung
Threshold voltage roll-off is analyzed for sub-10 nm asymmetric double gate (DG) MOSFET. Even asymmetric DGMOSFET will increase threshold voltage roll-off in sub-10 nm channel length because of short channel effects due to the increase of tunneling current, and this is an obstacle against the miniaturization of asymmetric DGMOSFET. Since asymmetric DGMOSFET can be produced differently in top and bottom oxide thickness, top and bottom oxide thicknesses will affect the threshold voltage roll-off. To analyze this, thermal emission current and tunneling current have been calculated, and threshold voltage roll-off by the reduction of channel length has been analyzed by using channel thickness and top/bottom oxide thickness as parameters. As a result, it is found that, in short channel asymmetric double gate MOSFET, threshold voltage roll-off is changed greatly according to top/bottom gate oxide thickness, and that threshold voltage roll-off is more influenced by silicon thickness. In addition, it is found that top and bottom oxide thickness have a relation of inverse proportion mutually for maintaining identical threshold voltage. Therefore, it is possible to reduce the leakage current of the top gate related with threshold voltage by increasing the thickness of the top gate oxide while maintaining the same threshold voltage.
Volume: 9
Issue: 1
Page: 163-169
Publish at: 2019-02-01

Load balancing clustering on moodle LMS to overcome performance issue of e-learning system

10.12928/telkomnika.v17i1.10284
Mujiono; Universitas Mercu Buana Sadikin , Raka; Universitas Mercu Buana Yusuf , Arif Rifai; Universitas Mercu Buana D.
In dealing with the rapid growth of digitalization, the e-learning system has become a mandatory component of any Higher Education (HE) to serve academic processes requests. Along with the increasing number of users, the need for service availability and capabilities of eLearning are increasing day by day. The organization should always look for strategies to keep the eLearning always able to meet these demands. This report presents the implementation of Load Balancing Clustering (LBC) mechanism applied to Moodle LMS in an HE Institution to deal with the poor performance issues. By utilizing existing tools such as HAProxy and keepalived, the implemented LBC configuration delivers a qualified e-learning system performance. Both qualitative and quantitative parameters convince better performance than before. In four months of the operation there is no user complaint received. Meanwhile, in the current semester has been running for two months, the up-time is 99.8 % of 52.685 minutes operational time.
Volume: 17
Issue: 1
Page: 131-138
Publish at: 2019-02-01

A colour-based building recognition using support vector machine

10.12928/telkomnika.v17i1.11609
Mas Rina; Universiti Putra Malaysia Mustaffa , Loh Weng; Universiti Putra Malaysia Yee , Lili Nurliyana; Universiti Putra Malaysia Abdullah , Nurul Amelina; Universiti Putra Malaysia Nasharuddin
Many applications apply the concept of image recognition to help human in recognising objects simply by just using digital images. A content-based building recognition system could solve the problem of using just text as search input. In this paper, a building recognition system using colour histogram is proposed for recognising buildings in Ipoh city, Perak, Malaysia. The colour features of each building image will be extracted. A feature vector combining the mean, standard deviation, variance, skewness and kurtosis of gray level will be formed to represent each building image. These feature values are later used to train the system using supervised learning algorithm, which is Support Vector Machine (SVM). Lastly, the accuracy of the recognition system is evaluated using 10-fold cross validation. The evaluation results show that the building recognition system is well trained and able to effectively recognise the building images with low misclassification rate.
Volume: 17
Issue: 1
Page: 473-480
Publish at: 2019-02-01

Optical millimeter wave generation utilizing stimulated brillouin scattering for radio over fiber system

10.11591/ijeecs.v13.i2.pp818-824
M.M.H Husaini , C.B.M Rashidi , SN Azemi , S.A Aljunid , M.S Anuar
Optical millimeter-wave signal generation in Radio over Fiber (RoF) based on external modulators using different modulation schemes such as Single-Sideband (SSB), Double-Sideband (DSB) are experimentally compared. The major fallout for external modulation scheme system performance to downgrade is due to dispersion and the fading effect in optical signal generation while generating high Bit Error Rate (BER) when involving long distance delivery.  In this work, we proposed mm-wave signal utilize Stimulated Brillouin Scattering (SBS) scheme which  indicates the best performance amongst the scheme based on simulation that it achieves to propagate longest of distance over fiber, highest receiver sensitivity, the lowest BER and coherence of Mach-Zehnder Modulator (MZM) extinction ratio. Mm-wave signal of 40 Ghz and 10 Gb/s data rate was generated with the plotting of eye diagram.
Volume: 13
Issue: 2
Page: 818-824
Publish at: 2019-02-01

Squirrel cage induction motor scalar control constant V/F analysis

10.12928/telkomnika.v17i1.8818
K. A. M.; Universiti Teknikal Malaysia Melaka Annuar , M. R.; Universiti Teknikal Malaysia Melaka Sapiee , Rozilawati M.; Universiti Teknikal Malaysia Melaka Nor , M. S. M.; Universiti Teknikal Malaysia Melaka Azali , M. B. N.; Universiti Teknikal Malaysia Melaka Shah , Sahazati Md.; Universiti Teknikal Malaysia Melaka Rozali
In constant V/f control technique it is assume that the stator resistance and leakage inductance drops are negligible, especially at high speed and small load. In other words, the back emf is comparatively large at high speed and hence these voltage drops can be neglected. By maintaining constant V/f, constant Eg/f and hence constant air-gap flux is assumed. This assumption is however invalid at low speeds since a significant voltage drop appears across the stator impedance. The terminal voltage, V no longer approximates  ag. By using MATLAB Simulink, the open-loop constant V/f is simulated. It is shown that the performance of the drive deteriorates at low speeds. The improvement in the performance by applying voltage boost is shown and discussed.
Volume: 17
Issue: 1
Page: 417-424
Publish at: 2019-02-01

Transistor mismatch effect on common-mode gain of cross-coupled amplifie

10.12928/telkomnika.v17i1.11587
Zainul; Brawijaya University Abidin , Eka; Brawijaya University Maulana , Ramadhani Kurniawan; Brawijaya University Subroto , Wijono; Brawijaya University Wijono
In this paper, the analytical approach of MOS transistor mismatch effect on common-mode gain of cross-coupled amplifier is presented. Transconductance (MOS transistor parameter) mismatch effect on common-mode gain of cross-coupled amplifier was analyzed. This study was started with mathematical derivation for representing the mismatch effect of transconductance between 2 differential pairs of crosscoupled amplifier due to common-mode voltage. The derivation result was simulated based on Monte Carlo simulation with random transconductance mismatch rate from 0.05% until 1%. The common-mode gain increases 36.9 dB and average common-mode gain is -81.1 dB. The transconductance mismatch rate increases followed by increase in common-mode gain. The results can be used by circuit designers to design analog circuits, especially operational amplifier used for biosignals processing to minimize the common-mode gain of their circuits. This research presents aid to circuit designers to improve their circuits performance.
Volume: 17
Issue: 1
Page: 448-452
Publish at: 2019-02-01

Big 5 ASEAN capital markets forecasting using WEMA method

10.12928/telkomnika.v17i1.11625
Seng; Universitas Multimedia Nusantara Hansun , Marcel Bonar; Universitas Multimedia Nusantara Kristanda , P. M.; Universitas Multimedia Nusantara Winarno
ASEAN through ASEAN Economics Community (AEC) 2020 treaty has proposed financial integration via capital markets integration in order to aim comprehensive ASEAN economic integration. Therefore, the need to have a proper prediction of ASEAN capital market becomes a major issue. In this study, we took big 5 ASEAN capital markets, i.e. Straits Times Index (STI), Kuala Lumpur Stock Exchange (KLSE), Stock Exchange of Thailand (SET), Jakarta Stock Exchange (JKSE), and Philippine Stock Exchange (PSE) to be forecasted using WEMA method. Weighted Exponential Moving Average (WEMA) is a new hybrid moving average method which combines the weighting factor calculation in Weighted Moving Average (WMA) with the procedure of Exponential Moving Average (EMA). WEMA has successfully been implemented and used to forecaste discrete time series data, but never being used to forecast ASEAN capital markets. In this study, we took further action by implementing the WEMA method with brute force approach for scaling factor tuning on big 5 ASEAN capital markets. From the experimental results, we found that WEMA has successfully forecasted all those exchanges. By looking at the forecast error measurement, it gives the best performance on PSE and worst performance on SET dataset among all datasets being considered in this study.
Volume: 17
Issue: 1
Page: 314-319
Publish at: 2019-02-01

Classification of neovascularization using convolutional neural network model

10.12928/telkomnika.v17i1.11604
Wahyudi; University of Airlangga Setiawan , Moh. Imam; University of Airlangga Utoyo , Riries; University of Airlangga Rulaningtyas
Neovascularization is a new vessel in the retina beside the artery-venous. Neovascularization can appear on the optic disk and the entire surface of the retina. The retina categorized in Proliferative Diabetic Retinopathy (PDR) if it has neovascularization. PDR is a severe Diabetic Retinopathy (DR). An image classification system between normal and neovascularization is here presented. The classification using Convolutional Neural Network (CNN) model and classification method such as Support Vector Machine, k-Nearest Neighbor, Naïve Bayes classifier, Discriminant Analysis, and Decision Tree. By far, there are no data patches of neovascularization for the process of classification. Data consist of normal, New Vessel on the Disc (NVD) and New Vessel Elsewhere (NVE). Images are taken from 2 databases, MESSIDOR and Retina Image Bank. The patches are made from a manual crop on the image that has been marked by experts as neovascularization. The dataset consists of 100 data patches. The test results using three scenarios obtained a classification accuracy of 90%-100% with linear loss cross validation 0%-26.67%. The test performs using a single Graphical Processing Unit (GPU).
Volume: 17
Issue: 1
Page: 463-472
Publish at: 2019-02-01

A wideband reflectarray antenna based on organic substrate materials

10.12928/telkomnika.v17i1.9593
H. I.; University Tun Hussein Onn Malaysia (UTHM) Malik , M. Y.; University Tun Hussein Onn Malaysia (UTHM) Ismail , Sharmiza; Forest Research Institute Malaysia (FRIM) Adnan , S. R.; University Tun Hussein Onn Malaysia (UTHM) Masrol , N.; University Tun Hussein Onn Malaysia (UTHM) Nafarizal
Significant improvements in terms of bandwidth of reflectarray antennas have been achieved by introduction of innovative paper substrate dielectric materials. Three differently custom composed organic dielectric substrates have been characterized for dielectric properties using a broadband technique based on open ended coax cable method. The substrates show low dielectric permittivities of 1.81, 1.63 and 1.84 along with a loss tangent of 0.053, 0.047 and 0.057. Validation of using the proposed substrates for reflectarray antenna was done by modelling and fabricating reflectarray unit elements on the three substrates. Scattering parameter analysis of unit reflectarray elements show encouraging results with a broadband frequency response of 340 MHz at a phase gradient of 0.14 º/MHz. Thus the proposed substrate could serve exceptionally to address the narrow bandwidth problem in reflectarray antennas.
Volume: 17
Issue: 1
Page: 8-14
Publish at: 2019-02-01

Shape analysis for classification of breast nodules on digital ultrasound images

10.11591/ijeecs.v13.i2.pp837-844
Hanung Adi Nugroho , Hesti Khuzaimah Nurul Yusufiyah , Teguh Bharata Adji , Widhia K.Z Oktoeberza
One of the imaging modalities for early detection of breast cancer malignancy is ultrasonography (USG).  The malignancy can be analysed from the characteristic of nodule shape.  This study aims to develop a method for classifying the shape of breast nodule into two classes, namely regular and irregular classes.  The input image is pre-processed by using the combination of adaptive median filter and speckle reduction bilateral filtering (SRBF) to reduce speckle noises and to eliminate the image label.  Afterwards, the filtered image is segmented based on active contour followed by feature extraction process.  Nine extracted features, i.e. roundness, slimness and seven features of invariant moments, are used to classify nodule shape using multi-layer perceptron (MLP).  The performance of the proposed method is evaluated using 105 breast nodule images which comprise of 57 regular and 48 irregular nodule images.  The results of classification process achieve the level of accuracy, sensitivity and specificity at 96.20%, 97.90% and 94.70%, respectively.  These results indicate that the proposed method successfully classifies the breast nodule images based on shape analysis.
Volume: 13
Issue: 2
Page: 837-844
Publish at: 2019-02-01
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