Judul: Peramalan Pasokan Tandan Buah Segar dan Penjualan Minyak Sawit Kasar Menggunakan Jaringan Syaraf Tiruan Propagasi Balik
Abstrak: Crude palm oil sales forecasting and palm oil fresh fruit bunch stock forecasting are common problems for palm agro industry company. The low rate of sales due to wrong prediction may influence company’s expansion plan. Moreover, crude palm oil stock is strongly dependent on palm oil fresh fruit bunch stock in each fields. The objective of this study is to create a model for sales forecasting of crude palm oil by using backpropagation Neural Network. This study uses secondary data which contains historical data of crude palm oil sales dependent on TBS stocks from 3 fields (inti, plasma, luar). The data is obtained from PT. Perkebunan Nusantara (PTPN) XIII term of January 2005 to December 2007. Factors that influence backpropagation neural network model are the number of neurons in the hidden layer and the learning rate. The conclusion obtained based on the result test is that the level of accuracy of the Backpropagation Neural Network in predicting the supply of Palm Fresh Fruit Bunch and Crude Palm Oil sales is more competitive than the accuracy of ARIMA time series data model for Palm Fresh Fruit Bunch and Crude Palm Oil sales with 750.45 for RMSE and 25.67 MAPE.
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Judul: Prediction of The Closing Price of Stock using Backpropagation Neural Network Method
Abstrak: Saham adalah tanda penyertaan modal seseorang atau badan usaha dalam suatu perusahaan atau perseroan terbatas. Sebelum melakukan investasi, para investor perlu mempelajari prospek harga saham di masa mendatang. Oleh karena itu, peramalan harga saham sangat diperlukan. Pada karya ilmiah ini, dilakukan prediksi harga saham menggunakan metode jaringan saraf tiruan perambatan balik. Metode ini memperhitungkan input, jumlah neuron, dan fungsi pembelajaran yang harus ditentukan. Berdasarkan penghitungan Mean Absolute Error (MAE) dan Mean Absolute Percentage Error (MAPE), jaringan yang paling optimal adalah jaringan yang menggunakan input harga pembukaan saham dan tingkat suku bunga dengan satu neuron dan fungsi pembelajaran traincgb. MAE yang diperoleh sebesar 237.7063 rupiah dan MAPE sebesar 2.934777%., Stocks are sign of a person’s or business entity’s capital participation in a company or limited liability company. Before making an investment, an investor needs to study the prospect of future stock price. Therefore, making a forecast of future stock is indispensable. In this paper, backpropagation neural network method is used to forecast stock closing price. This method takes into accounts the input variables, the number of neurons, and it requires a learning function which must be defined. Based on Mean Absolute Error (MAE) and Mean Absolute Percentage Error (MAPE), the most optimal network is achieved by using stock opening price and interest rate as input variables with one neuron and traincgb learning function. The obtained MAE is IDR 237.7063 and MAPE is 2.934777% which is relatively small.
Keyword: stock closing price, backpropagation neural network, forecasting

Judul: Hydroxyapatite-Chitosan Composite Coating on Stainless Steel 316 to Improve Corrosion Resistance
Abstrak: Metals that were used in bone implantation should have good corrosion resistance that were not easily corroded when implanted into the body. Metal corrosion resistance of stainless steel 316 can be enhanced through the metal coating by hydroxyapatite-chitosan composite with composition ratio of hydroxyapatite (gram) and chitosan 3% (mL) 0.2:0, 0.2:0.1, 0.2:0.5, 0.2:1.0, and 0.2:1.5. Besides improving the corrosion resistance of metal, the presence of chitosan also maintain the position of hydroxyapatite on metal surfaces. Corrosion resistance increases with increasing amount of chitosan added and the best composition of hydroxyapatite-chitosan composite was 0.2:1.0.
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