Judul: Pengaruh Kebijakan Bea Keluar Biji Kakao terhadap ekspor Cocoa Butter Indonesia ke Amerika Serikat
Abstrak: Penerapan kebijakan bea keluar biji kakao bertujuan untuk mendorong peningkatan ekspor cocoa butter. Amerika Serikat merupakan salah satu negara pengimpor dari cocoa butter Indonesia. Tujuan dari penelitian ini untuk menganalisis dan mendeskripsikan pengaruh kebijakan bea keluar biji kakao terhadap ekspor cocoa butter Indonesia ke Amerika Serikat. Penelitian menggunakan data times series tahunan dari 1990 sampai 2020. Metode yang digunakan adalah Error Correction Model (ECM). Hasil penelitian menunjukkan pada jangka panjang variabel harga internasional biji kakao, harga ekspor cocoa butter, dan kebijakan bea keluar biji kakao berpengaruh secara signifikan. Pada jangka pendek variabel harga ekspor cocoa butter berpengaruh positif secara signifikan terhadap ekspor cocoa butter Indonesia ke Amerika Serikat. Kebijakan bea keluar biji kakao dapat meningkatkan ekspor cocoa butter Indonesia ke Amerika Serikat sehingga pemberlakuan kebijakan ini dapat dilanjutan. Selain untuk mendorong pertumbuhan industri pengolahan, kedepannya mutu dari cocoa butter yang dihasilkan perlu dijaga dan ditingkatkan., The implementation of the cocoa bean export tax policy aims to encourage an increase in cocoa butter exports. The United States is one of the importing countries of Indonesian cocoa butter. The purpose of this study is to analyze and describe the effect of the export duty policy on cocoa beans from Indonesia's cocoa butter exports to the United States. The study uses annual times series data from 1990 to 2020. The method used is the Error Correction Model (ECM). The results showed that in the long term the international price of cocoa beans, cocoa butter export prices, and cocoa bean policies had a significant effect. In the short term, the variables of cocoa butter export prices have a significant positive effect on Indonesia's cocoa butter exports to the United States. The policy of exporting cocoa beans can increase Indonesian cocoa butter exports to the United States so that this policy can be continued. In addition to encouraging the growth of the processing industry, in the future the quality of the cocoa butter produced needs to be maintained and improved.
Keyword: cocoa beans export tax, ECM, export of cocoa butter

Judul: Analisis Dampak Sanitary and Phytosanitary Measures (SPS) Terhadap Ekspor Cocoa Butter Indonesia ke Pasar Eropa Barat
Abstrak: Kakao merupakan salah satu komoditas ekspor unggulan sub sektor perkebunan yang memiliki kontribusi cukup besar terhadap PDB Indonesia, dimana total nilai ekspor kakao (HS 1804, cocoa butter) mencapai 1,26 miliar USD dalam periode 2011 hingga 2021. Berdasarkan data UN Comtrade, tren ekspor cocoa butter Indonesia berfluktuatif namun cenderung meningkat pada periode 2014-2020. Fluktuasi nilai ekspor diduga disebabkan oleh penerapan Sanitary and Phytosanitary Measures (SPS) pada komoditas kakao dan turunannya semakin ketat. Penelitian ini menyajikan gambaran pemberlakuan SPS pada ekspor cocoa butter Indonesia di pasar Eropa Barat yang dianalisis dengan inventory approach. Tujuan utama penelitian ini adalah untuk mengetahui dampak SPS terhadap ekspor cocoa butter Indonesia di pasar Eropa Barat yang dianalisis menggunakan gravity model. Hasil penelitian menunjukkan Jerman sebagai negara yang memberlakukan kebijakan SPS dengan nilai frequency index dan coverage ratio tertinggi pada tahun 2020. Sementara itu hasil gravity model menunjukkan bahwa kebijakan SPS secara signifikan berpengaruh negatif terhadap volume ekspor cocoa butter Indonesia sedangkan variabel real effective exchange rate, economic distance, GDP riil Indonesia, dan produksi kakao berpengaruh positif secara signifikan terhadap volume ekspor cocoa butter Indonesia., Cocoa is one of the leading export commodities in the plantation sub-sector which has a sizeable contribution to Indonesia's GDP, where the total export value of cocoa butter reached 1.26 billion USD in 2011 to 2021. Based on UN Comtrade data, export trends on Indonesian cocoa butter fluctuates but tends to increase in 2014-2020. Fluctuations in the value of exports are thought to be caused by strict application of Sanitary and Phytosanitary Measures (SPS) on cocoa commodity and its derivatives. This study presents an overview of the implementation of SPS on Indonesian cocoa butter exports to the Western Europe market with inventory approach. The main objective of this study was to determine the impact of SPS on Indonesian cocoa butter exports in the Western Europe market with gravity model. This study shows that Germany is the country that implements the SPS policy with the highest frequency index and coverage ratio values in 2020. Meanwhile the results of the gravity model show that the SPS policy has a significant negative effect on Indonesia's cocoa butter export volume while the real effective exchange rate, economic distance, Indonesia's real GDP, and cocoa production have a significant positive effect on Indonesia’s cocoa butter export.
Keyword: cocoa butter, coverage ratio, frequency index, gravity model, SPS

Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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