Judul: Perbandingan Algoritme C4.5 dan CART pada Data Tidak Seimbang untuk Kasus Prediksi Risiko Kredit Debitur Kartu Kredit
Abstrak: Credit risk is the risk of customers inability regarding their debt payment obligations. Credit risk can lead to non-performing loans, thereby reducing bank earnings. Various techniques can model the revenue of a debtor. One of them is the decision tree. There are several decision tree algorithms that can be used as classifiers, for example: C4.5 and CART. However, the classification results may be inaccurate due to the imbalanced in the used data. One way that can be used to address this problem is to include methods of sampling strategies: for examples over-sampling and under-sampling. This research found that the implementation of sampling strategy on the use of C4.5 and CART can improve the average accuracy, precision, recall, and F-measure.
Keyword: 

Judul: Klasifikasi Naive Bayes pada Data Tidak Seimbang untuk Kasus Prediksi Resiko Kredit Debitur Kartu Kredit.
Abstrak: Banking business in Indonesia is still dominated by the credit business field. Most of the bank's revenue comes from this business field. Unfortunately, credit risk can cause problems in loans which can reduce the bank’s revenue. This research uses a Naive Bayes classification analysis on the imbalanced data for the predictions of debtor’s credit risk that are able to classify the future debtor into the following two categories: good or bad. Sampling strategy is used to overcome the problems of imbalanced data. Duplication oversampling, random oversampling, random undersampling, and cluster undersampling are chosen as the methods. It is found that the random oversampling method shows the best value after sampling strategy is conducted with an f-measure of 83.30%.
Keyword: undersampling., oversampling, naive bayes classification, imbalanced data, Credit risk

Judul: Extracellular Expression of thermostable Geobacillus stearothermophilus T1.2RQ Lipase for Biodiesel Production
Abstrak: The extracellular expression of enzymes in an excellent secretion host such as Bacillus subtilis is a useful strategy for making enzymes of industrial significance more affordable by lowering the cost of its downstream processing. Lipases are a category of hydrolases that catalyze the hydrolysis of triglycerides to glycerol and free fatty acids. Also, lipases catalyze the hydrolysis and transesterification of other esters as well as the synthesis of esters. They can perform very specific biotransformation reactions and are widely used in food, organic synthesis, detergents, cosmetic, and pharmaceutical industries. Geobacillus stearothermophilus T1.2RQ lipase is an industrially-desired thermostable lipolytic enzyme with an excellent hydrolytic and transesterification activity. This study aimed to express T1.2RQ lipase, in B. subtilis WB800 and ensure its secretion into the extracellular medium. Three signal peptides (AmyQ, Epr, LipA) and two promoters (Pgrac01 and Pgrac100) were used in the secretory-expression of T1.2RQ lipase, based on five constructed expression vectors constructed by restriction cloning and PCR mutagenesis. Sangers sequencing was used to verify constructs to ensure they are in the correct reading frame. Recombinants vectors, pHT43 (plasmid control), pHT43-T1.2RQ, pHT43- T1.2RQ_AmyQ, pHT43-T1.2RQ_Epr, and pHT43-T1.2RQ_LipA, were transformed by electroporation into Bacillus subtilis WB800. The electroporation was successful with the optimum condition of 2500V, 200 ohms, 25µF, and 5milliseconds. Recombinant B. subtilis pHT43 (negative control) and pHT43-T1.2RQlip + signal peptides were streaked on the lipidic agar, LA+TBN. All four recombinants, including the negative control (B. subtilis WB800-pHT43), produced clear zones on the TBN agar plate after overnight incubation (fig 2), indicating the presence of a lipolytic enzyme in all of the recombinant B. subtilis cells. pHT43-T1.2RQlip + signal peptides (AmyQ, Epr, and LipA) have clear zones with significantly higher diameters than B. subtilis WB800-pHT43 (negative control). This phenomenon suggests that the recombinant thermostable lipase T1.2RQ introduced into these cells was successfully expressed, thereby increasing the lipolytic capability of its host cells T1.2RQ lipase was expressed in 50ml terrific broth medium (TB) and the expression induced with 1mM IPTG. Lipase activity assay using p-nitrophenyl esters showed that all three signal peptides directed the secretion of T1.2RQ lipase into the extracellular medium. Signal peptide, LipA, resulted in the highest extracellular activity of 5.6 U/mL, which corresponds to a 6-fold increase over the parent B. subtilis WB800 strain. Meanwhile, signal peptides, AmyQ and Epr produced 4.2 U/mL and 3.4 U/mL activity respectively. SDS-Zymogram analysis confirmed that T1.2RQ lipase was correctly processed and secreted in its original size of 44 kDa. An attempt to further increase lipase expression level by promoter optimization showed that, contrary to expectation, promoter Pgrac100 exhibited similar expression levels as the original Pgrac01. Nevertheless, the demonstration of the successful secretion of T1.2RQ lipase in this work confirms the latter as a promising approach for the industrial production of the enzyme
Keyword: Bacillus subtilis, Expression, Extracellular, Heterologous, Lipase, Thermostable