Judul: Analisis Nilai Tambah Cokelat Batangan (Chocolate Bar) di Pipiltin Cocoa, Kebayoran Baru, Jakarta Selatan
Abstrak: Indonesia is the third largest world cocoa producer. Previously, Indonesia is just an exportir of cocoa beans. Producer of processing cocoa product is dominated by European countries. Although cocoa beans as a main raw product of chocolate was not produced in Europe. Thus, Indonesia should change their role from being a cocoa beans exporter to a cocoa finished product exporter. Indonesian government start to support manufacturing of cocoa beans by implementing export tax policy. The result of that policy is cocoa beans export volume decreased and increased in domestic cocoa industry capacity. Unfortunately, cocoa manufacturing industry is still more dominated by international companies such as Nestle, Marz, JB Cocoa Malaysia, and others than domestic small and medium enterprise. Nowadays, the most of small and medium enterprise produce compound chocolate and semi finished chocolate. For a long time, added value of cocoa beans processing was still enjoyed by international companies. One of small and medium enterprise in producing real chocolate from local cocoa beans is Pipiltin Cocoa in Kebayoran Baru, South Jakarta. Pipiltin Cocoa produce main product which is chocolate bar with local cocoa beans from Aceh and Bali. This research use two methods: Hayami and Syahza in counting added value. The result of this research showed that value added of chocolate bar by Pipiltin Cocoa as much as Rp 289 000 per kg cocoa beans which is used in production. Based on calculation result, added value of Pipiltin Cocoa’s chocolate bar which was analyzed by Hayami method is same as the results of added value calculation by using Syahza method.
Keyword: added value, chocolate industry, chocolate, Cocoa beans

Judul: Competitiveness of Indonesian Cocoa  Beans and Processed Cocoa Products in the International Market
Abstrak: Kakao memberikan kontribusi pendapatan nasional ketiga tertinggi setelah karet dan kelapa sawit. Sebagian besar kakao Indonesia diekspor dalam bentuk biji. Namun, setelah adanya kebijakan bea keluar terhadap biji kakao terjadi perubahan struktur ekspor yang semula didominasi biji bergeser menjadi produk olahan. Penelitian ini bertujuan untuk mengevaluasi perkembangan dan struktur ekspor kakao setelah adanya kebijakan bea keluar dan menganalisis daya saing biji kakao Indonesia dan beberapa produk olahannya. Metode yang digunakan adalah indeks Revealed Comparative Advantage (RCA), Indeks Spesialisasi Perdagangan (ISP), dan Export Product Dynamics (EPD). Hasil penelitian menunjukkan bahwa daya saing biji kakao Indonesia setelah adanya kebijakan bea keluar diukur dengan metode RCA mengalami penurunan signifikan bahkan pada tahun 2016 sampai 2018 nilai RCA biji kakao Indonesia kurang dari satu yang artinya biji kakao Indonesia tidak memiliki keunggulan komparatif. Sedangkan daya saing produk olahan kakao Indonesia kecuali coklat mengalami peningkatan, nilai RCA pasta kakao, lemak kakao, dan bubuk kakao menunjukkan ketiga produk tersebut memiliki keunggulan komparatif., Cocoa provides the third highest contribution to national income after rubber and palm oil. Most of Indonesia's cocoa is exported in the form of beans. However, after the export tax policy for cocoa beans, there was a change in the export structure, which was originally dominated by cocoa beans, shifted to processed products. This study aims to evaluate the development and structure of cocoa exports after the export tax policy and to analyze the competitiveness of Indonesian cocoa beans and some of their processed products. The methods used are Revealed Comparative Advantage (RCA), Trade Specialization Index (ISP), and Export Product Dynamics (EPD). The results showed that the competitiveness of Indonesian cocoa beans after the export tax policy measured by the RCA method decreased significantly, even 2016 to 2018 the RCA value of Indonesian cocoa beans was less than one, meaning that Indonesian’s cocoa beans did not have a comparative advantage. While the competitiveness of processed Indonesian cocoa products except chocolate has increased, the RCA value of cocoa paste, cocoa butter, and cocoa powder shows that these three products have a comparative advantage.
Keyword: Cocoa Beans, Cocoa Processed Products, Exports, RCA

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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