Judul: Analisis Usaha Pengrajin Tahu Sumedang Sebelum dan Setelah Kenaikan Harga Kedelai (Studi Kasus: Kecamatan Tanjungsari, Sumedang)
Abstrak: Soybean is one of the food that the price level is fluctuated. The soybean price increase will affect the soybean processing industry, one of which is tofu industry. The soybean prices increase are expected to affect the structure of cost, revenue, profit, and the efficiency of a business. This research aimed to analyze of tofu industry business before and after the soybean price increase. The method that used in the study was a census method. Data were analyzed quantitatively and qualitatively. The analytical tool used is the R / C ratio, paired t-test, and anova test. The results of the analysis of a total of 20 respondents showed that the soybean price increase has effect on the cost, revenue, profit, and the R/C ratio, as well as with an internal analysis of business scale. However, the results of the analysis at different levels of scale of business is no different. This is due to the small sample size in each scale of business and strategy performed relatively the same at every scale of business, so it can not represent the whole population in the District Tanjungsari, Sumedang.
Keyword: the soybean price increase, profit, efficinecy, different test, cost

Judul: Pengaruh peningkatan harga kedelai terhadap keuntungan dan nilai tambah industri tahu di Desa Leuweung Kolot Kecamatan Cibungbulang Kabupaten Bogor
Abstrak: Soybean is the important ingredient in soybean processing enterprises such as tofu and tempeh. The increase of soybean price that has affects the business sustainability of the household tofu industry who have limited capital and accessibility. The objective of this research is to analyse the effect of increasing soybean price to the cost structure, profit, and value-added of the tofu industry in Leuweung Kolot village. The analysis used in this study consisted of analysis for calculating profit, analysis of revenue and R/C ratio, also the value-added analysis by using Hayami method. Based on the research that had been conducted showed that the increase in soybean price affected the cost structure and profit of tofu industry. The increase in profit based on the strategy undertaken by the tofu industry to increase the selling price and decrease the size of tofu. Likewise with value added analysis indicated that the increase in soybean prices also affected the value added generated by the tofu industry in Leuweung Kolot village.
Keyword: value added, soybean, Profit

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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