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All Journal Jurnal Ilmu Dasar Matematika: Jurnal Teori dan Terapan Jurnal Sains Dasar Jurnal Teknik Industri: Jurnal Keilmuan dan Aplikasi Teknik Industri Teorema: Teori dan Riset Matematika International Journal of Supply Chain Management International Journal of Global Operations Research Jurnal Matematika Integratif

Elis Hertini

Departemen Matematika Fakultas Matematika Dan Ilmu Pengetahuan Alam Universitas Padjadjaran

Author-ID : 2858944

Computer Science & IT Control & Systems Engineering Decision Sciences, Operations Research & Management Economics, Econometrics & Finance Education Electrical & Electronics Engineering Engineering Environmental Science Industrial & Manufacturing Engineering Mathematics Mechanical Engineering Transportation

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Prediction of Tourist Arrivals to the Island of Bali with Holt Method of Winter and Seasonal Autoregressive Integrated Moving Average (SARIMA) Agus Supriatna; Elis Hertini; Dwi Susanti; Sudradjat Supian
Jurnal Sains Dasar Vol 6, No 2 (2017): October 2017
Publisher : Faculty of Mathematics and Natural Science, Universitas Negeri Yogyakarta

The tourism sector is one of the contributors of foreign exchange is quite influential in improving the economy of Indonesia. The development of this sector will have a positive impact, including employment opportunities and opportunities for entrepreneurship in various industries such as adventure tourism, craft or hospitality. The beauty and natural resources owned by Indonesia become a tourist attraction for domestic and foreign tourists. One of the many tourist destination is the island of Bali. The island of Bali is not only famous for its natural, cultural diversity and arts but there are also add the value of tourism. In 2015 the increase in the number of tourist arrivals amounted to 6.24% from the previous year. In improving the quality of services, facing a surge of visitors, or prepare a strategy in attracting tourists need a prediction of arrival so that planning can be more efficient and effective. This research used Holt Winter's method and Seasonal Autoregressive Integrated Moving Average (SARIMA) method to predict tourist arrivals. Based on data of foreign tourist arrivals who visited the Bali island in January 2007 until June 2016, the result of Holt Winter's method with parameter values α=0.1 ,β=0.1 ,γ=0.3 has an error MAPE is 6,171873. While the result of SARIMA method with (0,1,1)〖(1,0,0)〗12 model has an error MAPE is 5,788615 and it can be concluded that SARIMA method is better.Keywords: Foreign Tourist, Prediction, Bali Island, Holt-Winter’s, SARIMA.

Optimalisasi Waktu Investasi Dengan Real Option Menggunakan MATLAB S. Sudradjat; Elis Hertini; Siska D. Angraeni
Matematika Vol 9, No 1 (2010): Jurnal Matematika
Publisher : Universitas Islam Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29313/jmtm.v9i1.3480

Abstrak. Investasi merupakan masalah yang secara konseptual sulit dan kompleks untuk diselesaikan karena dalam investasi terkandung risiko atau terjadinya penyimpangan antara hasil yang diharapkan dengan hasil sesungguhnya, hal ini disebabkan karena faktor ketidakpastian. Pendekatan yang dilakukan untuk menghadapi ketidakpastian pembuatan keputusan investasi yang mengoptimalkan waktu investasi adalah model Real Option yang mengacu pada model Black Scholes. Terakhir sebagai ilustrasi diberikan contoh dan perhitungan numerik nilai Real Option yang dilihat sebagai call option atas saham dengan program aplikasi Matlab.Kata Kunci : investasi, Black Scholes, Real Option, optimalisasi, Matlab.Abstract. Investment problems is conceptually hard and complex to solve because we can find some risks or deviation between the expected result and the real result, this is because uncertainty factor. The approaching to face the uncertainty of investment policy making that optimize the time investment is “The Real Option” model which based from “The Black Scholes” model. Finally, we give illustrative examples and their numerical solutions of the real option that seen as call option on stock can use the Matlab Application program. Key words: Investment, Black Scholes, Real option, Optimization, Matlab.

Model Optimisasi Robust untuk Mengatasi Ketidaktentuan Estimasi Durasi Operasi pada Masalah Penjadwalan Ruang Operasi Rumah Sakit Diah Chaerani; Ija Royana; Elis Hertini
Jurnal Teknik Industri Vol. 19 No. 1 (2017): JUNE 2017
Publisher : Institute of Research and Community Outreach - Petra Christian University

Masalah penjadwalan ruang operasi di rumah sakit merupakan masalah keragaman durasi operasi yang memerlukan penjadwalan untuk mengurangi tingkat kesibukan ruang operasi. Masalah yang harus diselesaikan dalam penjadwalan ruang operasi adalah bagaimana menempatkan pasien ke dalam blok ruang operasi yang tersedia secara optimal untuk meminimumkan waktu tunggu pasien. Masalah ini dapat disajikan dalam sebagai masalah optimisasi dalam formulasi mixed integer linear programming (MILP). Pada prakteknya sering terjadi ketidaktentuan estimasi durasi operasi yang dapat mengakibatkan jadwal operasi tidak berjalan sesuai perencanaan awal, sehingga pasien tidak dapat dioperasi sesuai dengan waktu yang telah ditentukan. Dalam makalah ini dikaji pemodelan masalah optimisasi tak tentu dengan menggunakan teknik pemodelan Optimisasi Robust (OR) dalam hal mengatasi ketidaktentuan estimasi durasi operasi pada masalah penjadwalan ruang operasi rumah sakit. Dalam metodologi OR diperkenalkan Robust Counterpart (RC), dimana tujuan utama yang ingin dicapai adalah menguji level robustness dengan cara menguji formulasi model robust counterpart yang dihasilkan apakah dapat direpresentasikan dalam jenis kelas masalah optimisasi yang dapat terjamin sebagai kelas masalah yang computationally tractable. Pemilihan jenis himpunan taktentu untuk merepresentasikan data taktentu yang terlibat dalam pemodelan sangat menentukan, untuk memastikan apakah formulasi robust counterpart yang diperoleh merupakan masalah yang computationally tractable atau tidak. Dapat disimpulkan bahwa model RC yang diperoleh termasuk dalam kelas masalah yang computatioonally tractability, dalam hal ini model tak tentu dapat direpresentasikan dalam formulasi model optimisasi dalam bentuk linear programming (untuk box uncertainty set) dan conic quadratic programming (untuk ellipsoidal uncertainty set).

PERAMALAN JUMLAH KEDATANGAN WISATAWAN MANCANEGARA KE INDONESIA DENGAN METODE HOLT-WINTERS DAN HUBUNGANNYA TERHADAP PENDAPATAN DEVISA PARIWISATA Muhammad Aldrin Degasputra Chandrasa; Eman Lesmana; Elis Hertini
Teorema: Teori dan Riset Matematika Vol 5, No 2 (2020): September
Publisher : Universitas Galuh

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25157/teorema.v5i2.3790

Pariwisata merupakan sektor penghasil devisa penting di Indonesia. Dalam industri pariwisata, ketepatan dan kelengkapan prakiraan yang baik diperlukan dari pembuat kebijakan dan praktisi untuk mempersiapkan sarana-prasarana, akomodasi, dan transportasi wisatawan. Jumlah kedatangan wisatawan yang beragam tiap bulannya dan kedatangan yang berpola musiman sehingga diperlukan metode yang dapat memprediksi kedatangan wisatawan dengan tepat. Karena data kedatangan wisatawan berpola musiman dan tidak stasioner, pada paper ini akan digunakan metode peramalan Holt-Winters multiplikatif untuk meramalkan kedatangan yang berpola musiman, dan kemudian akan dicari hasil ramalan dengan pendapatan devisa pariwisata. Dari hasil penelitian ini didapat hasil ramalan dan hubungan dengan pendapatan devisa pariwisata yang kemudian hasil tersebut dapat digunakan sebagai bahan kajian instansi terkait dalam mengambil kebijakan mengenai pariwisata dan kedatangan wisatawan mancanegara, seperti pemerintah, pengelola tempat wisata, penyedia transportasi, dan penyedia akomodasi.

Supply Chain Management Planning for a Project Using the Fuzzy Logic and Crasing Program Method Elis Hertini; Julita Nahar
International Journal of Supply Chain Management Vol 9, No 4 (2020): International Journal of Supply Chain Management (IJSCM)
Publisher : International Journal of Supply Chain Management

Show Abstract | Download Original | Original Source | Check in Google Scholar

Project management is a strategy that needs to be done in project planning and scheduling. With the preparation of a good project management, it can be estimated the time and cost needed to run the project, so as to minimize cost losses due to possible project lags. Project scheduling is one element of planning results, which can provide information about project schedules, plans and progress. Project time management can be arranged using the Critical Path Method (CPM) and Program Evaluation and Review Technique (PERT). One alternative to accelerate project completion (Crashing) is by adding project costs using the Crasing Program Method. To overcome the uncertainty of scheduling time and project costs in calculations Fuzzy Logic is used. From the results of using Fuzzy Logic, we estimate the time and cost needed to carry out the project, so as to minimize cost losses due to possible time delays in the project. The results of using Fuzzy Logic on CPM and PERT project schedule on a house renovation project in Ujungberung Indah Bandung housing complex, requires a longer completion time, but the probability of completion of the project is higher, the use of the Crasing Program Method results in faster project completion times and lower incremental costs.

Principal Component Analysis (PCA) of Phytoplankton Community Relations Based on Physical-Chemical Structures for Supply Chain Management in the Waters of the Bangka Bay Region of West Bay Julita Nahar; Elis Hertini
International Journal of Supply Chain Management Vol 9, No 4 (2020): International Journal of Supply Chain Management (IJSCM)
Publisher : International Journal of Supply Chain Management

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Phytoplankton as one of the most important organisms in the territorial waters, which is the beginning of the food chain in a territorial waters. Phytoplankton have certain tolerance limits to physical-chemical factors so that they will form different community structures. The relationship between chemical physics parameters with phytoplankton communities in a territorial waters, can be used as an indicator of water quality. West Bangka Regency has considerable marine and fisheries resource potential, especially for marine aquaculture. So research on the structure of the phytoplankton community in relation to the physical-chemical parameters of seawater needs to be carried out to see indicators of fertility and availability of natural food in the waters that will be used as a marine aquaculture location. To find out the relationship between physico-chemical parameters and phytoplankton abundance, Principal Component Analysis (PCA) was used. Some physico-chemical parameters observed were temperature, brightness, pH, salinity, coated oxygen (DO), phosphate, nitrate, and ammonia. The results show the eigenvalues value of the main component 1 (PC1) represents about 41.78% of the diversity of data with its main identifying variable, namely temperature with a loading factor value of -0.885, brightness with a loading factor value of -0.8872 and salinity with a loading factor value of 0.824. For the main component 2 (PC2) represents about 28.16% of the diversity of data with its founder variable, pH with a loading factor value of -0.841. As for the main component 3 (PC3), it represents 18.67% of the diversity of data with its originating variable, Nitrate, with a loading factor value of -0,700. So that it can be formed into 3 clusters namely the first cluster is temperature and salinity, the second cluster is pH and nitrate and the third cluster is DO, phosphate, and ammonia.

The Forecasting of Foreign Tourists Arrival in Indonesia based on the Supply Chain Management: an Application of Artificial Neural Network and Holt winters Approaches Agus Supriatna; Elis Hertini; Jumadil Saputra; Betty Subartini; Alfan Azkiya Robbani
International Journal of Supply Chain Management Vol 8, No 3 (2019): International Journal of Supply Chain Management (IJSCM)
Publisher : International Journal of Supply Chain Management

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Tourism plays crucial role for improving the social and economic development of a country through open employment opportunities in surrounding tourism area. The supply chain mangement strategy can be effective in developing the turisim industry.The number of foreign tourists who come to Indonesia continues to increase from time to time. Therefore, tourist arrivals need to be forecasted to assist the government in providing optimal infrastructure and accommodation for tourists to avoid an imbalance between the number of tourists with the infrastructure and accommodation provided. The purpose of this study is to forecast the arrival of foreign tourists in Indonesia by using Artificial Neural Network and Holt-Winters approach esutilising the historical data from January 2011 to December 2017. From the calculation process, we found that MAPE (Mean Absolute Percentage Error) value of Artificial Neural Network and Holt-Winters approaches are 5.60% and 5.43%, respectively. So it can be concluded that the Holt-Winters approach is better than the Artificial Neural Network approaches in forecasting the foreign tourists arrival in Indonesia.

Designing Graphical User Interface (GUI) for Adjustable Robust Maximum Flow Problem Diah Chaerani; Naufal Badruzzaman; Elis Hertini; Endang Rusyaman
Jurnal Matematika Integratif Vol 17, No 1: April 2021
Publisher : Department of Matematics, Universitas Padjadjaran

Maximum flow problem is one of optimization problems which aims to find the maximum flow value that is traversed in a network system. This problem can be solved using existing algorithms and linear programming. In the case of maximum flow, often the parameters used vary due to certain factors. \cite{agustini} designed the Robust Counterpart Optimization Model for Maximum Flow Problems by assuming side and flow capacities from an indefinite point to destination point to solve the maximum flow problem with uncertainty. To facilitate the search for solutions with large amounts of data, a Graphical User Interface (GUI) was made. GUI is a pictorial interface of a program that can facilitate its users in completing their work such as counting, making, and so on. In this study, the GUI was created using Maple software and used the Adjustable Robust Counterpart Optimization Model made by \cite{agustini}. Thus, the search for solutions to maximum flow problems can be resolved quickly and efficiently only by entering the data needed for calculations in the GUI.

Multi-Item Inventory Control Using Economic Order Quantity (EOQ) Model with Safety Stock, Reorder Point, and Maximum Capacity in Retail Business Mubasysyir, Muhammad Hanif; Supian, Sudradjat; Hertini, Elis
International Journal of Global Operations Research Vol. 5 No. 1 (2024): International Journal of Global Operations Research (IJGOR), February 2024
Publisher : iora

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.47194/ijgor.v5i1.237

The presence of retail businesses in Indonesia has many positive impacts on the community, especially in improving the economy. The existence of buying and selling transactions involving suppliers, retailers, and the community as consumers can play a role in improving the national economy. Retail can be called a bridge for suppliers and consumers to meet their needs. The diversity of consumer needs requires retailers to provide a variety of products from many suppliers. Efforts that need to be made by retail businesses in order to minimize costs incurred are by controlling inventory. To prevent excessive expenditure, the inventory control method used is to apply the Economic Order Quantity (EOQ) model. The EOQ model can provide the optimum total inventory cost by adjusting the frequency of orders placed over a period of time. After obtaining the total inventory cost, the calculation of safety stock, reorder point, and maximum capacity can also be applied so that the inventory costs incurred can be minimal.

Determining Flood Protection Strategy with Uncertain Parameter Using Adjustable Robust Counterpart Methodology Chaerani, Diah; Robbi, Muttaqien Rodhiya; Hertini, Elis; Rusyaman, Endang; Paulus, Erick
Jurnal ILMU DASAR Vol 21 No 1 (2020)
Publisher : Fakultas Matematika dan Ilmu Pengetahuan Alam Universitas Jember

Flooding is a natural disaster that often occurs, it is not surprising that floods are one of the problems that must be resolved in various countries, one of which is Indonesia. Flood is very detrimental to the public because the impact could be the loss of material and non-material. A flood protection system is needed and must be managed properly. This aims in management of flood protection systems often requires efficient cost control strategies that are the lowest possible long-term costs, but still meets the flood protection standards imposed by regulators in all plans. In this paper a flood protection strategy is modeled using Adjustable Robust Optimization. In this approach, there are two kinds of variables that must be decided, i.e., adjustable and non-adjustable variables. A numerical simulation is presented using Scilab Software. Keywords: Flood Protection Strategy, Uncertainty, Adjustable Robust Optimization, Scilab Software.

Co-Authors Agus Supriatna Agus Supriatna Alfan Azkiya Robbani Betty Subartini Bhagawanta, Hanif Ibnu Diah Chaerani Dwi Susanti Eman Lesmana Endang Rusyaman Erick Paulus Ija Royana Julita Nahar, Julita Jumadil Saputra Mubasysyir, Muhammad Hanif Muhammad Aldrin Degasputra Chandrasa Naufal Badruzzaman Naufal Badruzzaman Robbi, Muttaqien Rodhiya Royana, Ija S. Sudradjat Siska D. Angraeni Sudradjat Supian Supian, Sudradjat

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