Judul: Pengoptimuman Masalah Persediaan dalam Menghadapi Penawaran Diskon dan Dua Jenis Biaya Backorder
Abstrak: Persediaan adalah stok bahan yang digunakan untuk mempermudah produksi pada suatu perusahaan manufaktur. Perusahaan perlu mampu mengatur jumlah kuantitas produk dan waktu pemesanan yang efektif. Terkadang perusahaan tidak memiliki persediaan yang cukup sehingga mengganggu proses pendistribusian produk. Kondisi tersebut disebut dengan backorder. Selain kondisi backorder, terkadang pemasok juga memberikan potongan harga kepada perusahaan manufaktur. Penawaran diskon akan mengakibatkan perusahaan membeli kuantitas pesanan khusus yang jumlahnya perlu ditentukan agar mendapatkan keuntungan maksimal. Salah satu model untuk masalah persediaan adalah Model Economic Order Quantity (EOQ). Karya ilmiah ini membahas Model EOQ dengan diskon dan Model EOQ dengan backorder yang dikembangkan untuk tiga skenario berbeda. Setiap skenario dibedakan berdasarkan waktu dan objek penerapan diskon. Selanjutnya, akan dihasilkan formulasi masalah persediaan untuk menentukan kuantitas pesanan khusus agar biaya total persediaan minimum pada setiap skenario., Inventory is the stock of materials used to facilitate production in a manufacturing company. Companies need to be able to manage the number of quantities and order time effectively. Sometimes the company does not have enough inventory, it interferes with the product distribution processes. This condition is known as backorders. In addition to backorder conditions, sometimes suppliers also provide price discounts to manufacturing companies. A discount offer makes the company buy an additional order quantity whose amount needs to be determined to get maximum profit. One of the models for inventory problems is the Economic Order Quantity (EOQ) model. This paper discusses the EOQ Model with discounts and the EOQ Model with backorders developed for three different scenarios. Each scenario based on the time and object of applying the discounts. Next, an inventory problem formulation is generated to determine the number of additional orders so that the total inventory cost is minimum in each scenario.
Keyword: backorder, discount, EOQ model, inventory control

Judul: Pengoptimuman Masalah Persediaan Barang yang Tidak Sempurna Disertai Backorder
Abstrak: Persediaan merupakan aset yang sangat penting bagi perusahaan, sehingga diperlukan pengelolaan persediaan yang tepat. Selama proses produksi berlangsung, barang yang dihasilkan tidak selalu sempurna. Barang tersebut biasanya diambil seketika dari stok saat proses penyortiran, sehingga perusahaan tidak memiliki persediaan yang cukup untuk memenuhi permintaan dari pelanggan. Kondisi ini dapat dikatakan backorder. Diasumsikan bahwa semua pelanggan bersedia untuk menunggu persediaan baru ketika terjadi kekurangan. Pada penelitian ini sistem persediaan yang dibahas adalah sistem persediaan dengan kendala barang yang tidak sempurna disertai backorder. Selanjutnya, dilakukan pengoptimuman untuk menentukan banyaknya barang yang akan dipesan dan jumlah backorder yang memaksimumkan nilai harapan dari total keuntungan bersih., Inventory is a very important asset for the company, so it is necessary to manage inventory properly. During the production process, the items produced are not always perfect. These item are usually taken instantaneously from stock during the sorting process, so that the company does not have sufficient inventory to satisfy demand from customers. This condition can be said to be backorder. It is assumed that all customers are willing to wait for new supplies when there is a shortage. In this study, the inventory system discussed is an inventory system with imperfect items constraints with backorder. Furthermore, optimization is performed to determine the number of items to be ordered and the number of backorder that maximize the expected value of the total net profit.
Keyword: backorder, kualitas tidak sempurna, model persediaan yang optimal, imperfect quality, optimal inventory model

Judul: Posisi Filogenetik Kura-Kura Carettochelys Insculpta  (Reptillia: Testudinata)
Abstrak: Carettochelys insculpta is an endemic freshwater turtle of southern Papua and northern Australia. Phylogenetic position of this turtle is remain unresolved until now. Most of the research conducted show close relationships of C. insculpta and members of Trionychidae family. However, some of the research show distance between C. insculpta and members of Trionychidae family. This research is conducted to analyze phylogenetic relationship between C. insculpta and other members of Testudinata using 12S rRNA, 16S rRNA, and both gene as markers. DNA samples were obtained from three different organisms of C. insculpta. Two species used as outgroups were Alligator mississippiensis and Iguana iguana. Phylogenetic analysis was carried out using Neighbor-Joining method with Felsenstein 1981 (F81) modeltest. A polytomy tree of Testudinata was produced by using 12S rRNA gene. However, analysis using 16S rRNA and both genes as markers confirmed that C. insculpta was located between the Chelonidae and the Trionychidae family.
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