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Abstrak :
This study addresses the hub network design problem considering demand uncertainty and hub congestion effects. The problem is formulated as a two-stage stochastic program with recourse model. The model provides a consistent set of hub locations, while adjusting network configuration in response to different demand realizations. A case study collected from real-world data was used to test the proposed model, and a sensitivity analysis was performed to know how several important parameters affected the solution

Abstrak :
Beginning with the Airline Deregulation Act of 1978 in US, followed by the European Union in 1997, airlines have been constructing route networks of their own choosing rather than operating ones implicitly chosen for them by civil aviation authority. These changes have had profound effects on many aspects of airline operation, particularly fares, service, quality, and safety. But, most importantly, airlines have altered their route structures by developing hub-and-spoke networks, and this has affected all of these aspects. This structure is likely to flourish around the world as a consequence of airline liberalization and the growing trend toward privatization of this industry. In a hub-and-spoke network, centrally located service facilities serve as the hubs. Flows from a set of outlying nonhub nodes arrive at hubs and, after regrouping, all leave the hub facilities bound either to other hubs or to their ultimate destinations. Thus, the flows from the same origin with different destinations are consolidated on the route to a hub facility and the flows with different origins but the same destination on the route out of a hub facility. The centralization and broader scope of operations let the system take advantage of economies of scale. This paper proposes a framework to optimize the flight network using hub-and-spoke system. This problem consists of the determination of hub number, hub location and route assignment in order to minimize the overall transportation cost. The model is solved using genetic algorithm approach. Two networking strategies are considered: 1. Strict hubbing, in which a spoke is assigned to exactly one hub and all flows to/from spoke are channeled trough the same hub and 2. Nonstrict hubbing, in which a spoke can be assigned to more than one hub under certain condition. Different values of airport fixed costs are also implemented. Variations of these strategies are evaluated along with various parameters of air transport production using data on air passenger flows between top 30 Indonesian airports in 2000. The result shows that the adoption of hub-and-spoke network increase the overall system performance with increasing load factor, frequency, coverage area, revenue passenger kilometer, available seat kilometer and more efficient utilization of aircraft. Moreover, Nonstrict hubbing strategy offers smaller total system cost, more routes and more nonstop flights.

Abstrak :
ABSTRAK
Studi keekonomian Marine CNG (Compressed Natural Gas) dengan membeli kapal Votrans dan menyewa kapal Coselle dilakukan pada tiga pembangkit yang direncanakan dibangun di Maluku. Metoda yang digunakan adalah Hub and Spoke dan Milk and Run. Keekonomian suplai CNG dibandingkan terhadap HSD (High Speed Diesel). Analisis keekonomian dilakukan dengan menghitung Net Present Value (NPV), Internal Rate of Return (IRR) dan Payback Period (PBP). Evaluasi keekonomian menunjukkan bahwa metoda Hub and Spoke dengan kapal Coselle tidak layak untuk digunakan. Metoda Hub and Spoke kapal Votrans, dan metoda Milk and Run baik Votrans maupun Coselle memberikan evaluasi keeokonomian yang layak. Rentang ideal untuk tariff gas adalah antara USD 2,5-6,5/MMBtu dibandingkan harga HSD USD 16,83/MMbtu. Metoda terbaik adalah dengan metoda Milk and Run Votrans 8 kapal yaitu NPV USD 493 M, dan Milk and Run 10 kapal dengan PBP 2,06 tahun dan IRR 41 %.

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ABSTRACT
Economical study of Marine CNG with buying Votrans vessel and renting Coselle vessel is applied at the future three power plants in the Maluku. The methods are Hub and Spoke and Milk and Run. Economical CNG supply is compared to the HSD (High Speed Diesel). The economic analysis is done by calculating the Net Present Value (NPV), Internal Rate of Return (IRR), and payback period (PBP). The economic evaluation shows that the Hub and Spoke method with renting Coselle ship cannot be applied. The Hub and Spoke method with buying Votrans, and Milk and Run methods with buying or renting ship gives a positive economic evaluation. The ideal gas tariff is between USD 2,5-6,5/MMbtu compared to HSD price USD 16,83/MMbtu. The best method is Milk and Run Votrans with 8 vessels with NPV USD 493 M, and Milk and Run Coselle with 10 vessel with PBP 2,06 years and IRR 59%.

Abstrak :
Aktivitas logistik merupakan salah satu bagian dari rantai pasok supply chain yang sedang menjadi perhatian dibanyak negara, salah satunya Indonesia. Di Indonesia biaya logistik masih terhitung tinggi, dikarenakan adanya ketidakseimbangan aliran distribusi barang di Indonesia bagian Barat dengan bagian Timur. Saat ini pemerintah Indonesia sedang dalam proses untuk mempersiapkan pembangunan pelabuhan peti kemas strategis untuk menyeimbangkan permasalahan anatara Indonesia Timur dengan Indonesia Barat. Dilihat dari konsep perencanaan tersebut maka dalam penelitian tersebut akan mencari alternatif model matematika untuk mencari rute yang optimal dengan fungsi tujuan meminimumkan biaya. Dari model matematika tersebut didapatkan rute yang menghubungkan dari Indonesia bagian barat dengan Indonesia bagian timur.

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Logistic is a part of supply chain that is being addressed in many countries, including Indonesia. The costly logistic of Indonesia is caused by imbalance trading between western and eastern regions in Indonesia. Challenging conditions come to the stakeholders particularly in the logistics sector. In this regard, the Government also plans to develop strategic container terminal ports. Concept of the planning in this research would also search for alternative a mathematics model to minimize logistics cost. From the model mathematics were obtained the route join the west Indonesia with eastern Indonesia.

Abstrak :
Indonesia merupakan negara kepulauan dimana setiap warga disetiap lokasi diwilayah negara berhak atas kebutuhan energi yang cukup untuk keberlangsungan hidup nya. LNG menjadi salah satu sumber energi yang bisa disuplai untuk kebutuhan disetiap wilayah Indonesia karena sifat nya yang mudah di transportasikan. Studi ini membahas pembangunan LNG HUB untuk wilayah distribusi Jawa bagian Timur, Bali dan Nusa Tenggara bagi pembangkit listrik tenaga gas yang saat ini masih menggunakan bahan bakar minyak sebagai sumber energi nya. Volume kapasitas LNG HUB yang akan dibangun didasarkan atas simulasi optimasi distribusi yang dilakukan dengan skema campuran antara hub and spoke serta milkrun. Studi ini menghasilkan perhitungan utilisasi kapal LNG 100% dengan kapasitas minimum LNG HUB 45.884 m³ serta keekonomian yang baik dalam hal ini IRR 24,33% dan NPV serta POT yang positif. ......Indonesia is an archipelagic country where each citizen is entitled to sufficient the energy needs for their survival. LNG, for instance, is one of the energy sources which is able to be supplied for the needs in each region of Indonesia as it is transportable. This study will discuss the development of LNG HUB for the distribution in Eastern Java, Bali, and Nusa Tenggara for gas-fired power plants that currently still use fuel oil as their energy source. The volume capacity of LNG HUB construction is based on the optimization simulations that is carried out with a mixed scheme between the hub and spoke as well as the milk run. This research conclude an LNG vessel distribution utilization 100%, a minimum capacity of LNG Hub 45.884 m³, and good economics in IRR 24.33% as well as positive NPV and POT.

Abstrak :
Tindakan pencegahan Covid 19 telah berdampak besar di banyak industri karena arus pelanggan yang tertekan yang biasanya mendukung bisnis. Covid-19 juga berdampak serius pada ekonomi global dan rantai pasokan global, termasuk pengiriman global. Letak geografis Indonesia yang diapit oleh dua samudera dan dua benua menjadikan wilayah laut Indonesia sebagai salah satu rute utama perdagangan dunia. Kondisi strategis Indonesia tidak diimbangi oleh rendahnya efisiensi logistik Indonesia. Makalah ini menghasilkan rekomendasi tentang rute logistik maritim Indonesia dan meningkatkannya untuk lebih mengeluarkan total biaya yang optimal. Perbaikan tersebut dicapai dengan menggunakan kombinasi rute yang belum dipertimbangkan dari penelitian sebelumnya. Masalahnya dimodelkan sebagai program bilangan bulat campuran dan Gurobi Optimization digunakan untuk menghasilkan solusi. ......Covid 19 precautions have had a major impact in many industries due to the depressed flow of customers who usually support businesses. Covid-19 also seriously impacts the global economy and global supply chains, including global shipping. Indonesia's geographical location flanked by two oceans and two continents makes Indonesia's sea area one of the main routes of world trade. Indonesia's strategic conditions are not offset by Indonesia's low logistics efficiency. This paper produces recommendations on Indonesia's maritime logistics routes and improves them to further incur optimal total costs. Such improvements are achieved using a combination of routes that have not been considered from previsious research. The problem is modeled as a mixed-integer program and Gurobi Optimization is used to generate the solution.

Abstrak :
Vehicle Routing Problem With Transshipment Facilities VRPTF adalah salah satu dari berbagai macam Vehicle Routing Problem VRP yang masih jarang untuk dibahas. Sejalan dengan isu mengenai logistik yang selalu menjadi sorotan bagi negara maju maupun berkembang. Penelitian ini bertujuan untuk membandingkan apakah pendekatan VRPTF cocok diterapkan pada distribusi logistik di Indonesia. Seperti yang kita ketahui Indonesia adalah salah satu negara kepulauan, sehingga untuk mendistribusikan barang antarpulau membutuhkan biaya yang cukup tinggi. Tujuan dari penelitian ini adalah memberikan perbandingan biaya dengan menggunakan metode VRPTF, metode Hub-dan-Spoke, dan metode Capacitated VRP, sehingga negara-negara yang mungkin mengalami kasus serupa dapat menerapkan metode ini dan mendapatkan model rute yang optimal. Penelitian ini dilakukan dengan mengambil studi kasus dari perusahaan yang menghasilkan produk non-perishable tidak mudah kadaluarsa/rusak dan membuat model dengan menggunakan Open Solver dan program VBA, keduanya di Excel. Penelitian ini menunjukkan bahwa metode VRPTF memberikan biaya optimal dibandingkan metode CVRP. ......Vehicle Routing Problem with Transshipment Facilities VRPTF is one of many various kind of Vehicle Routing Problem VRP which is still slightly discussed. As Logistic is always been an issue for both developed and developing country, this research aims to compare whether or not VRPTF is suitable applied to logistic distribution in Indonesia. As we know Indonesia is one of archipelagic countries, so distributing goods across the island requires high cost. The purpose of this paper is giving cost comparison by using VRPTF method, Hub and Spoke method, and Capacitated VRP method, so countries that may experience similar case can apply this method and get the optimize route model. This study was conducted by taking case study from company that produce non perishable product and generate the model using Open Solver and VBA program, both in Excel. This research indicates that VRPTF method giving optimize cost than other methods.

Abstrak :
Dalam industri jasa pengiriman paket dan kurir, waktu pengiriman merupakan faktor penting dalam memenuhi ekspektasi pelanggan. Jasa pengiriman paket menggunakan desain jaringan Hub-and-Spoke untuk memperoleh keuntungan ekonomis. Pengiriman di hari yang sama dapat dipastikan dengan merancang jaringan dengan batasan waktu ketat. Penelitian ini berfokus untuk merancang metode yang mampu menjawab keputusan utama terkait perancangan desain jaringan Hub-and-Spoke, yaitu: jumlah dan lokasi hub optimal, serta alokasi node lainnya ke hub. Data waktu tempuh dikumpulkan untuk setiap pasang lokasi. Metode Uncapacitated Single Allocation p-Hub Median Problem dan K-Means clustering digunakan untuk merancang jaringan Hub-and-Spoke awal. Bentuk jaringan direct link kemudian diubah ke bentuk jaringan rute dengan implementasi algoritma Local Search dan model Integer Programming. Desain jaringan optimal dipilih dengan mempertimbangkan jumlah kebutuhan kendaraan. Hasil dari kedua metode menunjukkan bahwa tiga merupakan jumlah hub optimum.

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In package delivery and courier services industry, delivery time is one important factor in meeting customer expectations. Delivery package services use Hub-and-Spoke network design to achieve economies of scale. Same-day delivery services can be ensured by designing network with tight travel time constraints. This study focuses in designing method that could answer the main decisions in Hub-and-Spoke network design, which are: the optimal number and locations of hubs, along with the allocations of other nodes to hubs. Travel time data were collected between every origin-destination pair. Uncapacitated Single Allocation p-Hub Median Problem and K-Means clustering methods were used to design the initial Hub-and-Spoke network. The directly linked network then transformed into a routed network by implementing Local Search algorithm and an Integer Programming model. The optimal network design was chosen by considering the number of vehicles needed. Results from both methods shown that three is the optimum number of hubs.

Abstrak :
Global revenue by passenger kilometers over the last ten years has grown at an average of 4.7 percent per year. The high growth of air transport must be offset by equivalent airport investment: perhaps even a doubling of the percentage growth of numbers of passengers. The purpose of this paper is to build a development model for investment in hub-and-spoke airport networks. The methodology developed in this paper uses systems dynamics theory. The benefit of using this approach is that the variables in the model are determined through a systems thinking process; the determination of variables through such a thinking process considers causality between variables dynamically, logically, and realistically within a complex aviation industry system. The simulation model shows that using a system dynamics approach can be used to simulate airport infrastructure investment development in a hub-and-spoke network. One of the subsystems is congestion; the result of simulation of this subsystem yields the behavioral characteristics, which show that a surge in demand (which is then offset by the provision of capacity or capacity enlargement) will eventually become stable, indicated by a lack of lines on the runway side. This means that decreases in congestion will increase passenger demand, and will also enhance potential investment in airport infrastructure.

Abstrak :
This research aims to find a proper measure of network connectivity in hub and spoke system for airlines in South-East Asia. As modification to previous studies that considered customer satisfaction dimensions of derouting index, connection time, connection time in relation to flight time, number of stops, frequency, and commercial objectives of passenger revenue and passenger demand, this study will also consider additional parameter of departure and arrival time. The performance evaluation model will be applied on 7 (seven) hubs from 6 (six) airlines in South East Asia, namely Cengkareng and Denpasar Hub of Garuda Indonesia, Singapore hub of Singapore Airlines, Bangkok hub of Thai Airways, Kuala Lumpur Hub of Malaysia Airlines, Manila Hub of Philippines Airlines and Ho Chi Minh Hub of Vietnam Airlines. Numerical analysis will be conducted to evaluate the hubs with the proposed connectivity measure. Comparative analysis will be applied to the result of the measure. The result of this research will help Garuda to optimize the existing hub by suggesting strategy initiatives to expand the network and improving the connectivity. Garuda could create effective operational and marketing policy to support the design of the network structure.

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Penelitian ini bertujuan untuk mencari perhitungan yang tepat bagi konektivitas dari sistem hub dan spoke untuk maskapai-maskapai di Asia Tenggara. Sebagai modifikasi dari studi sebelumnya yang mempertimbangkan parameter dari kepuasan penumpang yakni indeks derouting, connection time, hubungan connection time dengan jam terbang, jumlah perhentian, frekuensi, dan tujuan komersial yakni pendapatan dari penumpang dan permintaan penumpang, penelitian ini juga akan mempertimbangkan waktu tambahan parameter yakni waktu keberangkatan dan kedatangan. Model evaluasi kinerja akan diterapkan pada 7 (tujuh) hub dari 6 (enam) maskapai di Asia Tenggara, yakni hub Cengkareng dan Denpasar dari Garuda Indonesia, hub Singapura dari Singapore Airlines, hub Bangkok dari Thai Airways, hub Kuala Lumpur dari Malaysian Airlines, hub Manila dari Philippine Airlines, dan hub Ho Chi Minh dari Vietnam Airlines. Analisa numerik akan dilakukan untuk mengevaluasi hub dengan perhitungan yang diterapkan. Analisis komparatif akan diterapkan pada hasil perhitungan. Hasil penelitian ini akan membantu Garuda Indonesia untuk mengoptimalkan hub-nya dengan memberi saran untuk inisiatif strategi dalam melakukan ekspansi jaringan dan meningkatkan konektivitas. Garuda dapat menciptakan kebijakan operasional dan komersial yang efektif untuk mendukung rancangan struktur jaringannya.