TELKOMNIKA (Telecommunication Computing Electronics and Control)			
            
            
            
            
            
            
            
            Submitted papers are evaluated by anonymous referees by single blind peer review for contribution, originality, relevance, and presentation. The Editor shall inform you of the results of the review as soon as possible, hopefully in 10 weeks. Please notice that because of the great number of submissions that TELKOMNIKA has received during the last few months the duration of the review process can be up to 14 weeks. Communication Engineering, Computer Network and System Engineering, Computer Science and Information System, Machine Learning, AI and Soft Computing, Signal, Image and Video Processing, Electronics Engineering, Electrical Power Engineering, Power Electronics and Drives, Instrumentation and Control Engineering, Internet of Things (IoT)
            
            
         
        
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"Vol 11, No 2: June 2013" 
                    
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23 Documents 
                    
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                            On the Security of NMAC and Its Variants 
                        
                        Fanbao Liu; 
Changxiang Shen; 
Tao Xie; 
Dengguo Feng                        
                         TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 11, No 2: June 2013 
                        
                        Publisher : Universitas Ahmad Dahlan 
                        
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                                    DOI: 10.12928/telkomnika.v11i2.940                                
                                                    
                        
                            
                                
                                
                                    
Based on the three earlier MAC (Message Authentication Code) construction approaches, we propose and analyze some variants of NMAC. We propose  some key recovery attacks to  these  NMAC  variants, for  example, we can  recover  the  equivalent  inner  key  of NMAC  in  about O(2n/2) MAC  operations, in  a related key  setting. We  propose  NMAC-E, a  variant of NMAC  with  secret  envelop,  to  achieve  more  process  efficiency  and  no  loss  of security, which needs only one call to the  underlying hash  function, instead of two invocations in HMAC.
                                
                             
                         
                     
                    
                                            
                        
                            An Improved Image Contrast Assessment Method 
                        
                        Yuanyuan Fan; 
Yingjun Sang; 
Guang Hu Guang Hu; 
Zaijin Zhou; 
Yunrong Hao                        
                         TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 11, No 2: June 2013 
                        
                        Publisher : Universitas Ahmad Dahlan 
                        
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                                    DOI: 10.12928/telkomnika.v11i2.930                                
                                                    
                        
                            
                                
                                
                                    
Contrast is an important factor affecting the image quality. In order to overcome the problems of local band-limited contrast, a novel image contrast assessment method based on the property of HVS is proposed. Firstly, the image by low-pass filter is performed fast wavelet decomposition. Secondly, all levels of band-pass filtered image and its corresponding low-pass filtered image are obtained by processing wavelet coefficients. Thirdly, local band-limited contrast is calculated, and the local band-limited contrast entropy is calculated according to the definition of entropy. Finally, the contrast entropy of image is obtained by averaging the local band-limited contrast entropy weighed using CSF coefficient. The experiment results show that the best contrast image can be accurately identified in the sequence images obtained by adjusting the exposure time and stretching gray respectively, the assessment results accord with human visual characteristics and make up the lack of local band-limited contrast.
                                
                             
                         
                     
                    
                                            
                        
                            Fault Diagnosis for Substation with Redundant Protection Configuration Based on Time-Sequence Fuzzy Petri-Net 
                        
                        Haiying Dong; 
Xiaonan Li                        
                         TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 11, No 2: June 2013 
                        
                        Publisher : Universitas Ahmad Dahlan 
                        
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                                    DOI: 10.12928/telkomnika.v11i2.911                                
                                                    
                        
                            
                                
                                
                                    
Due to timing inconsistency, dual protection configuration and uncertainty diagnosis result characteristics of 750kV substation, fault diagnosis method of substation with redundant protection configuration which based on time sequence fuzzy Petri nets is proposed. In this method, redundant knowledge about fault component is represented by using two sets of protected information. On that basis, component redundant diagnosis-model based on time sequence fuzzy Petri net is constructed, which can be decomposed into main and redundant subnet-model. In this model, initial-information credibility is determined using information-entropy, timing constraint is checked, and initial-information credibility is corrected using the relationship between acted protection and breaker. Compared with fuzzy Petri net diagnosis method take no account of timing constraint, this method can not only identify the malfunction information, but also obtain a certain result.
                                
                             
                         
                     
                    
                                            
                        
                            Power Quality Signal De-noising with Sub band Adaptive Algorithm 
                        
                        Yingjun Sang; 
Yuanyuan Fan                        
                         TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 11, No 2: June 2013 
                        
                        Publisher : Universitas Ahmad Dahlan 
                        
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                                    DOI: 10.12928/telkomnika.v11i2.936                                
                                                    
                        
                            
                                
                                
                                    
A new level-dependent sub band adaptive noise reduction algorithm based on wavelet transform is proposed in order to improve the effect of power quality signal de-noising for power quality monitoring system. This threshold algorithm has two adjustable parameters to adjust the threshold both fine and coarsely, and the optimal parameters are determined by BP neural networks algorithm. Power disturbance data is referred to actual power disturbance data at IEEE open source and applied for test. The test results indicate that the proposed algorithm could denoise the different kind of power disturbances effectively, and the signal noise ratio is improved further with a smaller mean square error.
                                
                             
                         
                     
                    
                                            
                        
                            Determining the Excitation Voltage of Axial Flux Wound Rotor Synchronous Generator 
                        
                        Abdul Multi; 
Iwa Garniwa                        
                         TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 11, No 2: June 2013 
                        
                        Publisher : Universitas Ahmad Dahlan 
                        
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                                    DOI: 10.12928/telkomnika.v11i2.926                                
                                                    
                        
                            
                                
                                
                                    
The axial flux wound rotor generator has field winding that must be connected to a dc voltage source. By varying the excitation voltage, its electric performance might  be controlled to meet the need of a load voltage attached to its terminal. The designed generator is small-scale capacity which has 1 kW, 380 V and 750 rpm. The generator has a single double-sided slotted wound stator sandwiched between twin rotor. The effect of excitation voltage changes on its performance can be seen from the result of calculations using the given equations. The calculation results reveal electric quantities suited with respect to performance of the machine. If the voltages increase, the losses will decrease; but higher the excitation voltage, higher the efficiency and the terminal voltage. It has been found out that for the excitation voltage11 V, the efficiency and the terminal voltage are 85.12 % and 380V respectively.
                                
                             
                         
                     
                    
                                            
                        
                            The Improvement of Chord Protocol about Structured P2P System 
                        
                        Yong Chen; 
Long-zhao Sun; 
Huan-lin Liu; 
Wei-zhong Xiao                        
                         TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 11, No 2: June 2013 
                        
                        Publisher : Universitas Ahmad Dahlan 
                        
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                                    DOI: 10.12928/telkomnika.v11i2.941                                
                                                    
                        
                            
                                
                                
                                    
Chord protocol is one of the most classical protocols in structured P2P system, with the good effect, reliability, high query efficiency, and many other advantages. However, Chord agreement remains two main shortcomings the one that the searching speed of resources is slower, and the other that the detention of routing is higher. This paper in view of these shortcomings, combination with modification, then put forward the new Chord structure that super nodes and common nodes coexist, super nodes management general nodes. The new structure using Zipf-law determines the proportion of super nodes and ordinary nodes. The last, the new structure is simulated by simulation software, and the improved Chord protocol make better the previous shortcoming through the new structure compares with the Chord protocol.
                                
                             
                         
                     
                    
                                            
                        
                            Acoustic Performance of Exhaust Muffler Based Genetic Algorithms and Artificial Neural Network 
                        
                        Bing Wang; 
Xiaoli Wang                        
                         TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 11, No 2: June 2013 
                        
                        Publisher : Universitas Ahmad Dahlan 
                        
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                                    DOI: 10.12928/telkomnika.v11i2.931                                
                                                    
                        
                            
                                
                                
                                    
 The noise level was one of the important indicators as a measure of the quality and performance of the diesel engine.Exhaust noise in diesel engines machine accounted for an important proportion of installed performance exhaust muffler and it was an effective way to control exhaust noise. This article using orthogonal test program for the muffler structure parameters as input to the sound pressure level and diesel fuel each output artificial neural network (BP network) learning sample. Matlab artificial neural network toolbox to complete the training of the network, and better noise performance and fuel consumption rate performance muffler internal structure parameters combination was obtained through genetic algorithm gifted collaborative validation of artificial neural networks and genetic algorithms to optimize application exhaust muffler design is entirely feasible.
                                
                             
                         
                     
                    
                                            
                        
                            Formula Expression of Airgap Leakage flux Coefficient of Axial-Flux Permanent Magnet Motor 
                        
                        Xiao Gong; 
Yanliang Xu; 
Feng Xin                        
                         TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 11, No 2: June 2013 
                        
                        Publisher : Universitas Ahmad Dahlan 
                        
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                                    DOI: 10.12928/telkomnika.v11i2.912                                
                                                    
                        
                            
                                
                                
                                    
Airgap leakage flux coefficient is one of the main parameters which must be given ahead of time when performing initial designs or getting performance results by magnetic circuit analysis for any kinds of electrical machines. Three -dimensional finite element method (3D-FEM) is the most reliable one to obtain the accurate leakage flux coefficient for axial-flux permanent magnet (AFPM) motor which definitely takes a much long time and is not advantageous to the motor’s initial and optimal design. By constituting the accurate lumped-parameter magnetic circuit (LPMC) model and computing the resultant magnetic reluctances, the analytical formula of the leakage flux coefficient of AFPM is given which is verified by 3D-FEM and the prototyped AFPM experiment. 
                                
                             
                         
                     
                    
                                            
                        
                            Performance of Channel Estimation in MIMO-OFDM Systems 
                        
                        Subuh Pramono; 
Eddy Triyono                        
                         TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 11, No 2: June 2013 
                        
                        Publisher : Universitas Ahmad Dahlan 
                        
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                                    DOI: 10.12928/telkomnika.v11i2.937                                
                                                    
                        
                            
                                
                                
                                    
 This paper presented the performance of faded channel estimation method on orthogonal frequency division multiplexing-multiple input multiple outputs (OFDM-MIMO) i.e. least squares (LS) and minimum mean squared error (MMSE). Channel impuls response (CIR) was  required to overcome the intersymbol interference (ISI). Channel impuls response information was obtained from channel estimation processing. Iterance simulation used monte-carlo technique to determine the performance of bit error rate (BER) and mean squared error (MSE). Simulation results show that the mean squared error performance on MIMO system was better than the SISO system. On MMSE channel estimation, the MIMO 2Tx-2Rx system provided ± 2 dB improvement that compared to SISO system at value of MSE 10-2.Furthermore,MIMO 3Tx-2Rx produce improvement about 1.5 dB, MIMO 4Tx-2Rx improve about 3.5 dB at BER 10-4,respectively.The MIMO 2Tx-2Rx system, MMSE channel estimation produced better performance ± 1 dB than LS channel estimation with sufficient SNR value for MSE 10-2 .Pilot arrangement, the simulation results show that the block type-pilot arrangement produced better performance than the comb type-pilot arrangement at fast fading channel. Block type-pilot arrangement system produced better ± 10 dB than the comb type-pilot arrangement with MMSE method at value of BER 2 10-2. 
                                
                             
                         
                     
                    
                                            
                        
                            Research and Design on Navigation Electronic Map System 
                        
                        Wanwu Li Wanwu Li; 
Lin Liu; 
Honglei Dai; 
Chang Qu Chang Qu; 
Xiaotong Yang                        
                         TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 11, No 2: June 2013 
                        
                        Publisher : Universitas Ahmad Dahlan 
                        
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                                    DOI: 10.12928/telkomnika.v11i2.927                                
                                                    
                        
                            
                                
                                
                                    
This paper puts forward the new definition on the basis of the original concept of the navigation electronic map, designs the structure of the navigation electronic map system which contains three parts: hardware equipment, data system and software system, and analyzes each part of them in detail, finally this paper discusses the functional framework of the navigation electronic map.