Judul: Economic Feasibility Analysis of Smallholder Dairy Farming
Abstrak: Desa Mundu, Kecamatan Tulung merupakan salah satu sentra peternakan sapi perah di Kabupaten Klaten. Keberadaan peternakan berimplikasi pada timbulnya limbah serta potensi pencemaran lingkungan akibat aktivitas peternakan. Peternakan sapi perah yang terdapat di desa ini yaitu peternakan sapi perah dengan biodigester dan tanpa biodigester. Penerapan konsep ekonomi sirkular menggunakan teknologi biodigester menghasilkan biogas, sludge, dan slurry yang meningkatkan manfaat usaha peternakan sapi perah serta dapat mengurangi timbulnya pencemaran lingkungan. Oleh karena itu, perlu dilakukan analisis kelayakan aspek non-finansial yang meliputi aspek teknis; sosial dan lingkungan; kelembagaan, institusional, manajerial; dan komersial usaha peternakan sapi perah biodigester dan non-biodigester di Desa Mundu. Analisis proyeksi kelayakan ekonomi kedua pilihan usaha ditinjau dari kriteria investasi NPV, IRR, Net B/C, dan payback period layak dijalankan. Namun, usaha peternakan sapi perah biodigester lebih unggul. Hasil analisis sensitivitas terhadap biaya perbaikan biodigester menunjukkan bahwa usaha peternakan biodigester layak dijalankan dan tidak mempengaruhi usaha secara signifikan. Analisis switching value menunjukkan penurunan harga jual susu berpengaruh sangat signifikan pada kedua pilihan usaha, sedangkan kenaikan harga konsentrat dan ampas tahu tidak berpengaruh secara signifikan terhadap keberlangsungan usaha., Mundu Village, Tulung District is one of the centers of dairy farming in Klaten Regency. The existence of farms has implications for the generation of waste and the potential for environmental pollution due to farming activities. Dairy farms in this village are dairy farms with biodigesters and without biodigesters. The application of the circular economy concept using biodigester technology produces biogas, sludge, and slurry which increases the benefits of dairy farming and can reduce the incidence of environmental pollution. Therefore, it is necessary to analyze the feasibility of non-financial aspects including technical; social and environmental; institutional, managerial; and commercial aspects of biodigester and non-biodigester dairy farming in Mundu Village. The analysis of economic feasibility projections of both business options in terms of NPV, IRR, Net B/C, and payback period investment criteria is feasible. However, the biodigester dairy farming business is superior. Sensitivity analysis of biodigester repair costs showed that biodigester farming is feasible and does not significantly affect the business. The switching value analysis shows that a decrease in the selling price of milk has a very significant effect on both business options, while an increase in the price of concentrate and tofu pulp does not significantly affect business sustainability.
Keyword: ekonomi sirkular, Switching Value, biogas, sensitivitas, slurry

Judul: Economic Benefits of Biogas Energy Use from Dairy Cow Dung (Case Study: Mundu Village, Tulung District, Klaten Regency)
Abstrak: Desa Mundu merupakan salah satu desa sentra peternakan sapi di Jawa Tengah. Aktivitas peternakan dengan jumlah ternak yang banyak menghasilkan limbah dalam jumlah besar sehingga berpotensi mencemari lingkungan. Eksternalitas negatif dari peternakan dapat diminimalisir dengan memanfaatkan limbah ternak menjadi biogas. Biogas sebagai energi terbarukan mampu mensubstitusi penggunaan bahan bakar fosil. Desa Mundu telah memiliki 67 unit digester biogas, namun ada beberapa unit yang sudah tidak aktif karena kurangnya perawatan dan pemahaman dari peternak. Berdasarkan hal tersebut tujuan dari penelitian ini yaitu; (1) menganalisis potensi energi biogas, (2) menganalisis manfaat ekonomi penggunaan limbah ternak menjadi biogas, (3) merumuskan strategi keberlanjutan pemanfaatan biogas di Desa Mundu. Metode yang digunakan adalah analisis potensi energi biogas, analisis konsumsi energi rumah tangga peternak, analisis SWOT dan QSPM. Hasil penelitian menunjukkan bahwa (1) potensi energi biogas mencapai 176,57 m3/hari dari keseluruhan peternak sapi. (2) Penggunaan energi biogas memberikan manfaat ekonomi berupa penghematan pengeluaran pembelian gas elpiji dengan rata-rata sebesar Rp56.535,00/bulan/KK. (3) Strategi keberlanjutan yang menjadi prioritas utama adalah mendorong pengoptimalan potensi kotoran ternak sapi menjadi biogas sebagai sumber energi alternatif yang ramah lingkungan dalam memenuhi kebutuhan energi masyarakat Desa Mundu., Mundu Village is one of the dairy farming centers in Central Java. Farming activities with a large number of livestock produce large amounts of waste that have potential to pollute the environment. Negative externalities can be minimized by utilizing livestock waste into biogas. Biogas as a renewable energy can substitute the use of fossil fuels. Mundu Village has 67 biogas installation units. Unfortunately, there are several units that are no longer active due to lack of maintenance and understanding from the farmers. The objectives of this study are to; (1) analyze the potential of biogas energy, (2) analyze the economic benefits of using livestock waste into biogas, (3) formulate a strategy for the sustainability of biogas utilization. The methods used in this research are analysis of biogas energy potential, analysis of farmer household energy expenditure, SWOT and QSPM analysis. The results showed that (1) biogas energy potential reached 176,57 m3/day. (2) The use of biogas energy provides economic benefits, with an average savings value is Rp56.535,00/month/household. (3) The priority sustainability strategies is to encourage the optimization of the potential of cow dung into biogas as an alternative energy source to meet the energy needs of the Mundu Village community.
Keyword: biogas energy potential, renewable energy, sustainability strategy, 

Judul: Construction of Strongly Optimal Binary Linear Code with Minimum Distance 9 and 11
Abstrak: A binary linear code of length n over q F is a subspace of n q F . A code has three parameters that attached to it, namely length, dimension, and minimum distance. A code with length n, dimension k and minimum distance d is often called [n, k, d ]-code. Usually, when two parameters are given, then we want to find a code that has the best value for the last parameter. Based on Gilbert- Varshamov bound, if a [n, k, d ]-code exists and can not be expanded, we call it a strongly optimal code. In this paper, we construct strongly optimal code with minimum distance 9 and 11. In constructing the code, we created a theorem and algorithm based on Gilbert-Varshamov bound before we implement the algorithm to MAPLE programming language. Because of computational limitations, the program can only construct up to k = 10 for d = 9 and k = 12 for d = 11.
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