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.
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Judul: Analisis Regresi Logistik dan CART untuk Credit Scoring dengan Penanganan Kelas Tak Seimbang
Abstrak: Tidak adanya jaminan pada suatu jenis kredit akan membuat risiko kredit (gagal bayar) yang dihadapi oleh pihak bank semakin tinggi. Penerapan prinsip kehati-hatian oleh bank diterapkan dengan mengelola portofolio kredit yang dimiliki, sehingga potensi risiko yang terjadi dapat diukur dan dikontrol dalam suatu model. Credit scoring menggambarkan seberapa besar kemungkinan debitur akan macet dengan pembayaran. Pada penelitian ini dibandingkan pemodelan credit scoring antara analisis regresi logistik dan Classification and Regression Trees (CART) dalam mengklasifikasikan debitur yang nantinya dapat digunakan oleh bank untuk membuat atau mengevaluasi kebijakan terkait kredit. Permasalahan klasifikasi pada ketidakseimbangan kelas salah satunya dapat ditangani dengan Synthetic Minority Oversampling Technique (SMOTE). Hasil penelitian ini menunjukkan bahwa analisis Regresi Logistik dengan penanganan SMOTE menghasilkan kinerja yang lebih baik karena memiliki nilai sensitifitas yang lebih tinggi daripada analisis CART dan tidak terdapat perbedaan nilai terlalu besar pada nilai Area Under Curve (AUC). Peubah yang berpengaruh signifikan dalam klasifikasi debitur (lancar, macet) adalah tingkat pendidikan, status kepemilikan rumah, dan pendapatan., The absence of collateral for a type of credit will increase the bank's credit risk (failed to pay). Banks apply the precautionary principle by managing their credit portfolios so that potential hazards that occur can be measured and controlled in a model. Credit scoring describes how likely a debtor will fail with payments. This study aimed to compare logistic regression analysis and Classification and Regression Trees (CART) in classifying debtors to evaluate credit policies. One of the problems in classification is unbalanced data. Synthetic Minority Oversampling Technique (SMOTE) is a technique to handle the unbalanced problem in classification. The results show that the logistic regression model with SMOTE has higher sensitivity than the CART model, and there was no difference in Area Under Curve (AUC). The variables that have significant effects on the classification of debtors (good, bad) are level of education, homeownership status, and income.
Keyword: CART, Credit Scoring, Logistic Regression, Credit Risk, SMOTE

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