Judul: Identifikasi campuran nada pada suara piano menggunakan codebook
Abstrak: It has been identified blend of tones, either as a single tone or a mix tones using the mel-frequency cepstrum coefficients (MFCC) as feature extraction and modeling of codebook for pattern recognition. The voices which used are the sound of piano and identified as 12 single-tones and 66 mix of tones recorded with 11 kHz on the duration of 1 second. The making of codebook is applied step by step, that is the codebook with the blend and the codebook of tones (single and mixed tones) which was developed using clustering techniques. The results of research showed that the optimum number of codewords is 20 with width of frames is 256 data, with an accuracy is 98.2%. However, there are some tones which are difficult to be identified, they are CC#, CD, CF, and A#B which has accuracy of each below 50%. For C# tone is more often recognized as C#D# tone, for the CC# tone is more often identified as C tone, for CD tone is more often recognized as C# tone, the CF tone is more often identified as C# tone and CF# tone, while for the A#B tone is more often identified with A# tone. Some errors happen in this recognition because those tones have similiar signal pattern so that they have the vector points which adjacent to each other.
Keyword: 

Judul: Pengenalan Chord pada Alat Musik Gitar Menggunakan Codebook dengan Teknik Ekstraksi Ciri MFCC
Abstrak: Human auditory system is capable of extracting rich and meaningful data from complex audio signal. To recognize chord sequences that played in some kind of music is not an easy task. People need big effort to train their sense of hearing so they can recognize that kind sound of chords. This condition is also valid in a computer system. Finding the key and labeling the chords automatically from music are great use for those who want to do harmonic analysis of music. Hence automatic chord recognition has been a topic of interest in the context of Music Information Retrieval (MIR) for several years, and attempts have been made in implementing such systems using well understood signal processing and pattern recognition techniques. This research is about to recognize the sound of chord that played and recorded by guitar instrument. There are 24 major-minor chords that used in this research. MFCC is used as feature extraction and the number of coefficient cepstral that used are 13 and 26. Each chord signal that has been extracted then clustered using K-means algorithm with 8, 12, 16, 20, 24, 28, 32 k numbers to create codebook that use as a model of each chord. For the recognition process, there are two methods that used in this research, unstructured recognition and structured recognition. For the result, this research produces two kinds model of codebook that are codebook with 13 coefficients and codebook with 26 coefficients. Both types of codebook show a good result with accuracy level above 88%. The best result yielded from usage of 26 coefficient cepstral with structured recognition. It’s accuracy level reach 97%. Hence the usage of 26 coefficient cepstral is better than the usage of 13 coefficient cepstral with difference of accuration level is about 7%. This research also shows the affectation of the numbers k-means that used. An increasing accuration level shown by increasing the amount of k-cluster.
Keyword: 

Judul: Pengaruh vaksinasi terhadap dinamika populasi pada model SIR (Susceptible-Infected-Recovered)
Abstrak: SIR model can be used to model the spread of diseases in a closed population based on certain assumptions. In this research, the SIR model is formulated by including the factor of vaccination. As the result, the model has been shown to have two equilibrium points, i.e. disease free and endemic equilibrium. A simulation study is carried out to illustrate the model. The results show that some equilibrium points are asymptotically stable. Moreover, a minimum level of vaccination has been defined. For the vaccination level less than the minimum level, increase in the vaccination level results in decrease of the proportion of infected individuals in the corresponding equilibrium point. On the other hand, for the vaccination level greater than the minimum level, increase in the vaccination level results in decrease the proportion of susceptible individuals in the corresponding equilibrium point. Furthermore, when vaccination level is greater than the minimum level, it is found that the time needed for the disease to extinct is shorter.
Keyword: