Judul: Pengaruh Kenaikan Harga Kedelai terhadap Profitabilitas dan Nilai Tambah Usaha Tahu (Studi Kasus Usaha Tahu Doa Ibu di Jakarta Timur)
Abstrak: Tahu merupakan jenis makanan olahan dari kacang kedelai yang memiliki rata-rata konsumsi tertinggi di Jakarta Timur. Kedelai yang digunakan sebagai bahan utama dalam pembuatan tahu merupakan kedelai impor. Harga kedelai impor yang terus meningkat menjadi permasalahan yang dihadapi oleh pengrajin tahu karena mempengaruhi komponen biaya usaha dan secara langsung mempengaruhi tingkat profitabilitas dan nilai tambah usaha. Sehingga dibutuhkan penelitian ini dengan tujuan untuk mengetahui tingkat profitabilitas dan nilai tambah dari Usaha Tahu Doa Ibu. Perhitungan dilakukan dengan melakukan analisis struktur biaya, analisis harga pokok produksi, analisis titik impas, analisis profitabilitas, dan analisis nilai tambah. Hasil dari penelitian ini adalah tingkat profitabilitas yang didapatkan menunjukan hasil terbesar pada kondisi setelah kenaikan harga kedelai yang diikuti dengan kenaikan harga jual, yaitu sebesar 20%. Perhitungan nilai tambah pada output berupa tahu kulit dan tahu putih. Nilai tambah dan keuntungan yang didapatkan terbesar saat output berupa tahu kulit, yaitu sebesar Rp12.296/kg dan Rp11.039., Tofu is a type of processed food made from soybeans which has the highest average consumption in East Jakarta. The soybeans used as the main ingredient in making tofu are imported soybeans. The price of imported soybeans which continues to increase is a problem faced by tofu producers because it affects the components of business costs and directly affects the level of profitability and business added value. So this research is needed with the aim to determine the level of profitability and added value of Tofu Enterprises Doa Ibu. Calculations are performed by analyzing the cost structure, analysis of the cost of production, analysis of the break-even point, analysis of profitability, and analysis of added value. The results of this study are the level of profitability obtained which shows the greatest results in conditions after the increase in soybean prices followed by an increase in selling prices, which is equal to 20%. Calculation of added value to the output in the form of skin tofu and white tofu. The added value and profit is greatest when the output is skin tofu, which is IDR 12,296/kg and IDR 11,039.
Keyword: added value, profitability, soybean, tofu

Judul: Pengaruh Kenaikan Harga Kedelai terhadap Profitabilitas dan Nilai Tambah Usaha Tahu Bandung Kayun-Yun di Desa Cihideung Hilir Kecamatan Ciampea Kabupaten Bogor
Abstrak: Small industries is part of SME (Small Medium Enterprise) sector that gives an important role in Indonesia’s economic development. One of small industry that potentially to be developed is soybean industries such as tofu industries. Soybean price increase that occurred in 2013 affects tofu small industrial especially Usaha tahu bandung Kayun-Yun. The purpose of this research was to analyze the effect of soybean price increase on profitability and added value of Usaha Tahu Bandung Kayun-Yun. Research location was selected with the considerations that Ciampea subdistricts is one of the all subdistricts in Bogor district that known as tofu production centers. The results showed after soybean prices increased, the total cost increased by 44 957 794 per month, sales volume is still in 6700 pieces per day, the difference in cost of production in the amount of Rp 206/piece for 4 cm tofu and Rp 254/piece for 5 cm tofu, break-even point in goods value for 4 cm tofu in the amount of 586 pieces with 175 873 rupiah IDR and for 5 cm in the amount of 330 pieces with 115 557 rupiah IDR. Profitability value showed an increase of 30.25 % for 4 cm and 29.36 % for 5 cm tofu. The result of the added value also increased by Rp 8 672/kg for 4 cm tofu and Rp 8 195/kilogram for 5 cm tofu.
Keyword: added value., profitability, Usaha tahu bandung Kayun-Yun, Soybean

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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