Judul: Design of Taxes Early Warning System (TEWS) and Tax Revenue Model in Indonesia: The Application of Business Cycle Analysis and Taxes Revenue Performance Evaluation.
Abstrak: Currently, the mechanism of tax revenue allocation is still being distributed by top down mechanism, in which the distribution pattern is in the form of targets approved by DPR (House of Representatives) even though the initial draft comes from the government. Therefore, the national tax revenue forecast is not effective and needs a more comprehensive model to improve the tax planning This research is conducted to identify the environment turbulence which will affect economic fluctuation by using business cycle method. The behavior of this economic fluctuation will surely influence the fluctuation of tax revenue. The objective of this research is to identify this economic fluctuation by designing a model of early warning system which is called the Taxes Early Warning System (TEWS) and tax revenue modeling in Indonesia. In addition, this research will also examine the effects of these environmental shocks to the national tax revenue fluctuation in all tax offices in Indonesia. The research is conducted using monthly time series data and also applying two indicators : Income Tax and Value Added Tax. The result of this research is divided into four main topics. One of the important outcomes of this research, based on business cycles analysis, is the Taxes Early Warning System (TEWS) model. The best performance of Income Tax composite leading index is performed by Stepwise Regression model which consists of 14 particular components. While the best performance for the composite leading index of Value Added Tax is shown by Best Subset Regression model which consists of 9 particular components. From the VAR analysis result by Income Tax modeling series, it is known that there are 3 indicators having complete pass-through degrees more than one (complete pass through), which are hotel occupancy rate, money supply and fuel consumption. Meanwhile through the Value Added Tax series, the indicator shows the incomplete pass through degree. From the FEVD analysis result, both short term and long term, the external shock variability cannot explain the fluctuation of tax revenue as a benchmark series. The panel data analysis is used to examine the effects of economic fluctuation on 31 Kanwil DJP all over Indonesia and the results show that the fluctuation variable of TEWS gives positive effect to the tax income performance at Kanwil Khusus, Kanwil WP Besar 1 and 2, Kanwil Jakarta Selatan and Kanwil Jakarta Pusat. By using tax revenue modeling, it is known that within observing period, the surplus of income tax and value added tax has occured. The surplus proves that tax revenue projection until now is still being defined by top down policy pattern. Based on the research results, it can be concluded that there are five important variables which can influence the tax revenue performance, there are fuel consumptions, fuel price, domestic inflation, money supply and exchange rate. On the other hand, none of those variables are in the DGT authorization. In this case, DGT just only can anticipate the effects of the fluctuation of economic variable upon the tax revenue. To support the implementation of TEWS application, it has been designed the alternative strategy as an alternative
Keyword: Pajak Penghasilan (PPh), Pajak Pertambahan Nilai (PPN), siklus bisnis, shock, sistem peringatan dini, Taxes Early Warning System (TEWS), Penerimaan pajak, Series acuan, Derajat pass-through

Judul: Analisis leading indicator untuk pajak di Indonesia
Abstrak: Pajak sebagai salah satu instrument kebijakan fiskal di Indonesia selain pengeluaran pemerintah, merupakan hal yang sangat penting untuk dianalisis. Ketidaksesuaian antara target pajak dengan realisasinya menjadi suatu hal yang perlu diperhatikan. Selain itu, kontribusi yang besar yang diberikan pajak terhadap penerimaan negara membuat pajak penting untuk dianalisis. Untuk membantu pemerintah khususnya para pengambil kebijakan di bidang pajak, maka diperlukan suatu analisis mengenai keadaan pajak dimasa yang akan datang. Setelah nantinya diketahui bagaimana keadaan pajak dalam beberapa waktu ke depan, pemerintah dapat lebih mudah untuk mengambil kebijakan apa yang harus dilakukan terkait dengan peningkatan penerimaan pajak untuk negara. Salah satu solusinya adalah dengan menggunakan Composite Leading Index (CLI) yang banyak digunakan oleh beberapa negara untuk memprediksi keadaan perekonomian di negara yang bersangkutan
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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.
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