Judul: Improving the Quality of Coconut Cooking Oil in the  Koperasi W, Purworejo Regency
Abstrak: Koperasi W merupakan suatu unit usaha yang berbasis pengolahan kelapa menjadi produk turunannya. Permasalahan Koperasi W yaitu aroma dan warna minyak goreng kelapa yang kurang dapat diterima oleh konsumen. Minyak goreng kelapa tersebut diproduksi dengan metoda basah dari perasan santannya dan dimurnikan dengan tahapan pemanasan, netralisasi, pemucatan, penghilangan bau, dan penyaringan. Tujuan penelitian untuk meningkatkan mutu produk minyak goreng kelapa yang meliputi kadar air, asam lemak bebas, bilangan peroksida, aroma, dan warna minyak goreng kelapa yang kurang dapat diterima oleh konsumen produk minyak goreng kelapa Koperasi W. Metode yang digunakan untuk meningkat mutu minyak goreng kelapa yaitu dengan metode pemucatan menggunakan kombinasi arang aktif dan bentonit. Hasil perbaikan 1 yaitu kombinasi adsorben yang optimal adalah 5% bentonit: 5% arang aktif: 200g minyak. Rendemen skala pabrik yang diperoleh 82% dan hasil uji organoleptik untuk warna dan aroma sudah berbeda nyata. Uji mutu minyak yaitu kadar air 0,15%, FFA 1,09%, bilangan peroksida 8,88mek O2/kg, protein 1,9%, dan transmitan warna 94,5%. Perbaikan 2 minyak goreng diperoleh hasil rendemen 94%, kadar air 0,095%, FFA 0,2%, bilangan peroksida 2,4mek O2/kg, protein 0,5%, dan transmitan warna 98%. Pemucatan menggunakan kombinasi arang aktif dan bentonit dapat meningkatkan mutu minyak goreng kelapa, antara lain kadar air, asam lemak bebas, bilangan peroksida, warna, dan aroma minyak goreng kelapa. Kata kunci: adsorben, aroma, minyak goreng kelapa, mutu, warna., Koperasi W is a business unit based on coconut processing into its derivative products. The problem with Koperasi W is that the aroma and color of coconut cooking oil are not acceptable to consumers. Coconut cooking oil is produced by the wet method from the coconut milk and purified by heating, neutralization, blanching, deodorizing, and filtering. Research purposes to improve the quality of coconut cooking oil products which include water content, free fatty acids, peroxide number, aroma, and colour of coconut cooking oil which are less acceptable to consumers of the product Koperasi W. The method used to improve the quality of coconut cooking oil is the bleaching method using a combination of activated charcoal and bentonite. The result of improvement 1 is that the optimal adsorbent combination is 5% bentonite: 5% activated charcoal: 200g oil. The yield of factory scale obtained was 82% and the results of organoleptic tests for color and aroma were significantly different. Oil quality tests were 0.15% water content, 1.09% FFA, peroxide number 8.88 mekO2/kg, protein 1.9%, and color transmittance 94.5%. The repair of 2 cooking oils obtained yields of 94%, water content 0.095%, FFA 0.2%, peroxide number 2,4mekO2/kg, protein 0.5%, and color transmittance 98%. Bleaching using a combination of activated charcoal and bentonite can improve the quality of coconut cooking oil, including water content, free fatty acids, peroxide value, color, and aroma of coconut cooking oil.
Keyword: adsorbent, aroma, coconut cooking oil, quality, color

Judul: Cost Change Analysis of Coconut Cooking Oil Quality Improvement in Koperasi W
Abstrak: Koperasi W memurnikan minyak klentik menjadi minyak goreng kelapa melalui serangkaian proses pemanasan, netralisasi, pencucian, pemasakan, penyaringan, dan pengemasan. Perbaikan proses penghilangan warna dan bau telah berhasil melalui proses pemucatan menggunakan arang aktif dan bentonit. Penelitian ini dilakukan untuk menganalisis perubahan biaya dari solusi perbaikan proses pemucatan. Metode yang digunakan dalam penelitian ini adalah pengumpulan data dan analisis perubahan biaya. Analisis perubahan biaya tetap dan variabel dilakukan terhadap perbaikan proses, karena adanya penambahan bahan pemucat. Analisis kelayakan finansial dihitung atas Net Present Value (NPV), rasio pendapatan - biaya (Gross R/C), rasio keuntungan-biaya (Gross B/C), dan analisis sensitivitas. Perbaikan mutu minyak kelapa tersebut meningkatkan harga pokok produksi. Hasil analisis perubahan biaya menunjukkan nilai NPV sebesar Rp822.935.292 (positif), nilai Gross R/C 1,60 (>1), dan Gross B/C 0,60 (<1). Berdasarkan analisis NPV dan Gross R/C tersebut, perbaikan mutu minyak kelapa dinyatakan layak. Hasil analisis sensitivitas menunjukkan bahwa perubahan harga jual produk lebih sensitif daripada perubahan harga bahan baku. Dengan demikian solusi perbaikan proses pemucatan tersebut layak untuk diterapkan dan dioperasikan., Koperasi W refines crude coconut oil into coconut cooking oil through a series of processes, such as heating, neutralization, washing, cooking, filtering, and packaging. The improvement of the color and odor removal process has been successful through a bleaching process using activated carbon and bentonite. This research was conducted to analyze the cost change of the bleaching process improvement solution. The method used in this research were data collection and cost change analysis. Analysis of changes using fixed and variable costs was carried out on process improvements, due to the addition of bleaching agent. Financial feasibility analysis were calculated on Net Present Value (NPV), revenue-cost ratio (Gross R/C), cost-benefit ratio (Gross B/C), and sensitivity analysis. The improvement in the quality of coconut oil increases the cost of production. The results of the analysis of changes in costs show the NPV value of Rp822,935,292 (positive), the value of Gross R/C at 1.60 (> 1) and Gross B/C at 0.60 (<1). Based on the analysis of NPV and Gross R/C values, the improvement in the quality of coconut oil is declared feasible. The results of the sensitivity analysis show that changes in product selling prices are more sensitive than changes in raw material prices. Thus, the bleaching process improvement solution is feasible to be implemented and operated.
Keyword: coconut cooking oil, cost change analysis, process improvement

Judul: Dynamical System of Hepatitis B in Three Groups with Vaccination
Abstrak: The aim of this study is to modify the hepatitis B transmission model in three age groups involving vaccination from the model conducted by Zhoe and Zhang.The method used is to analyze the stability of the fixed point and its basic reproduction number (R_0). Performed stability analysis and numerical simulation to see population dynamics. Next, a sensitivity analysis of the parameters was carried out to see its effect on R_0. From the analysis obtained two fixed points, namely non-endemic and endemic fixed points. Non-endemic fixed points are locally asymptotically stable if R_0 <1 Meanwhile, the endemic fixed point is locally asymptotically stable if R_0 > 1. Hepatitis vaccination affects the number of susceptible population, because the more successful the vaccination, the smaller the number of susceptible populations so that the smaller the population will be infected.
Keyword: Dynamic, Hepatitis B, Vaccine, Mathematical model