Judul: Pembobotan RIDF pada Mesin Pencari Bahasa Indonesia untuk Ekspansi Kueri Menggunakan Analisis Konteks Lokal
Abstrak: Automatic query expansion is a technique for dealing with the fundamental issue of word mismatch between queries and documents in information retrieval. A number of approaches on query expansion have been studied, especially on techniques that analyze the corpus to discover word relationships (global technique) and those that analyze documents retrieved by initial query (local technique). Both techniques have their own advantages and limitations. Local context analysis is an automatic query expansion which is a combination of global and local techniques. The purpose of this research is to implement query expansion with local context analysis using TF (Term Frequency) RIDF (Residual Inverse Document Frequency) weighting method, a variation of IDF (Inverse Document Frequency) that assigns weights to terms according to the difference between the logs of the actual IDF and its prediction by Poisson model. The obtained performance of information retrieval was 15% average precision. The results also showed that the number of top-ranked documents and passages did not significantly affect the average precision. The more influential factor was the number of query expansions.
Keyword: 

Judul: Ekspansi Kueri pada Sistem Temu Kembali Informasi Berbahasa Indonesia menggunakan Kamus Dwibahasa
Abstrak: The most frequent problem on information retrieval is the users inability in representing information they need, in a query form. Thus, one of the solutions to overcome such situation is by applying query expansion technique. By applying the method, query will be expanded, and the new query produced will be used to do the search task. One of the approaches in determining the term of the expansion is Translation with Bilingualism Dictionary, which works through query translation process using dictionary, and the calculation of weight from each expanded candidate terms. In order to increase the relevance of the search result, this research uses Translation with Bilingualism Dictionary as the method to apply. Acknowledging the influence of the method, the research trial and error through the observation of the eleven recall precision number is applied to the produced retrieval result by using different expansion terms. Based on the observation of the produced precision number, it is identified that the use of Translation method in this research has not been successfull in increasing the relevance of the search results. The more expansion terms used, the smaller the precision number produced.
Keyword: 

Judul: Hydroxyapatite-Chitosan Composite Coating on Stainless Steel 316 to Improve Corrosion Resistance
Abstrak: Metals that were used in bone implantation should have good corrosion resistance that were not easily corroded when implanted into the body. Metal corrosion resistance of stainless steel 316 can be enhanced through the metal coating by hydroxyapatite-chitosan composite with composition ratio of hydroxyapatite (gram) and chitosan 3% (mL) 0.2:0, 0.2:0.1, 0.2:0.5, 0.2:1.0, and 0.2:1.5. Besides improving the corrosion resistance of metal, the presence of chitosan also maintain the position of hydroxyapatite on metal surfaces. Corrosion resistance increases with increasing amount of chitosan added and the best composition of hydroxyapatite-chitosan composite was 0.2:1.0.
Keyword: