Judul: Clustering Indonesian Documents Using Fuzzy C-Means
Abstrak: Document clustering enables a user to have a good overall view of the information contained in the document. Most classical clustering algorithms assign each data to exactly one cluster, thus forming a crisp partition of the given data. Recently, fuzzy clustering approach allows for degrees of membership, to which a data belongs to different clusters. Document clustering aims to make a cluster that is internally coherent but clearly different from other clusters. The documents that are used in this research are several documents from journal of horticulture and documents of medical plantations. All documents in the collections are clustered by using fuzzy C-Means algorithm. Furthermore, in this research threshold is used to weight the words that engage in the clustering process. The appropriate uses of threshold may give a better accuracy for the clustering result. The best result in this research is obtained when the threshold value is 1.5 and fuzzifier value is 2 for the documents from journal of horticulture, whereas for the documents of medical plantations the best result is obtained when the threshold value is 0.75 and fuzzifier value is 2.
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Judul: Pemilihan Fitur Dokumen Bahasa Indonesia untuk Pengelompokan dengan Metode K-Means
Abstrak: The field of document information retrieval has very diverse and rapidly-growing documents thereforethe need for methods to categorize documents effectively and efficiently increases. Categorizing documents can be performed using clustering techniques. This research uses the K-Means technique, one example of a partitioning clustering algorithm. K-Means is a simple algorithm that aims to get the appropriate grouping. Chi-square feature selection and the IDF were used to obtain the termsused as the unique identifiers of the documents. Clustering results with different feature selection techniques were made forcomparison to get the expected results.The accuracy values obtained for the IDF and the chi-square feature selection for data size 150 using rand index are26%, 75%, respectively.The accuracy values obtained for the IDF and the chi-square feature selection for data size 457 using rand index are31%, 37%, respectively. The accuracy values obtained for the IDF and the chi-square feature selection for data size 150 usingpurity measureare 97%, 96%, respectively. The accuracy values obtained for the IDF and the chi-square feature selection for data size 457 using rand index are 93%, 95%, respectively.
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Judul: Karakteristik Piezoelektrik Film LaxSr₁-xTiO3 di atas Substrat TCO
Abstrak: Studi material perovskite SrTiO3 sudah banyak dilakukan dan menunjukkan sifat feroelektrik, piezoelektrik, kuantum paraelektrik dan superkonduktor yang baik. Dengan penambahan dopant La2O3 diduga menambah performa sifat piezo dan karakteristik lainnya. Karakteristik film LaxSr₁-xTiO3 (LST) dengan variasi x= 0, 0.02, 0.04, 0.06 terbentuk pada suhu annealing 550 oC di atas substrat TCO melalui metode (Chemical Solution Deposition) CSD dan spin coating dengan 700 rpm pada kondisi suhu ruang dan tekanan atmosfer standar. Hasil menunjukkan, semakin banyak pendadah La maka nilai ketebalan film, ukuran rerata kristalit, parameter kisi, transmitansi, nilai konduktivitas (maksimum 589.7 S/cm pada sampel x=0.04 di frekuensi 10 Hz), nilai konstanta tegangan (c) dan muatan (d) piezo semakin meningkat. Dinamika bentuk grafik nilai tegangan (V) dan konstanta regangan mekanik (s) nampak mirip. Nilai V mencapai 0.127 V untuk x=0.06 (beban 50 g). Nilai maksimum c, d, s masing-masing mencapai 20.07 Vm/N, 1.14x10-8 C/N, 13642.71. Nilai band gap untuk x=0, 0.02, 0.04, 0.06 masing-masing 3.21 eV, 3.1 eV, 2.6 eV, 2.4 eV. La2O3 menambah performa sifat piezo, sehingga LST berpotensi sebagai sensor tekanan.
Keyword: CSD method, La2O3, LaxSr1-xTiO3, piezoelectric, TCO