Judul: Rancang Bangun Sistem Informasi Manajemen Pengendalian Suku Cadang untuk Pemeliharaan Preventif Mesin Produksi PT Sang Hyang Seri
Abstrak: The demands of seeds with good quality, precise production, and sufficient amount implies seed production activities of PT Sang Hyang Seri (SHS) should always be fast and optimal. Production factors that determine the outcome is, among others, the readiness of equipment for operation with excellent condition. Preventive maintenance can prevent damage of the machines that occurred on the machines before use. Good preventive maintenance can be achieved by control of parts that support the procurement needs of all preventive maintenance activities of the machine. Manager of the company plays an important role to always supervise the activities of the control and maintenance of machine in factory. Therefore, research is needed to design a management information system (MIS) that can help control the activities of preventive maintenance spare parts in machinery. The purpose of this study is to analyze the need for the user of the MIS, then designing system that can make activity of controling parts for preventive maintenance to be effective and efficient. The system was then developed as a web-based system by using the programming language PHP (Hypertext Preprocessor). Several system functions were developed in accordance with the targeted users, each with different access rights. There are four main subsystems, namely, machinery checking subsystem, stock management subsystem, subsystems purchase of components, and supervision subsystems
Keyword: management information systems, PT SHS, parts control, Preventive maintenance

Judul: Optimisasi Waktu Penggantian Komponen pada Mesin Produksi Benih Padi di PT Sang Hyang Seri
Abstrak: Key points in the maintenance of seed production machine is the analysis on economical machine lifetime, routine engine maintenance, spare parts replacement, and purchase a new machine. Such activities need to be analyzed can to produce a minimum of cost production. This study was conducted to observe the seed production process, analyze the critical level of the components on seed production machines, and to analyze the activities of maintenance and replacement of components on seed production machines. The research method is involving the identification of the seed production machines, i.e. kind of machines, need for engine power, engine speed, engine capacity, efficiency of the engine, and the maintenance history. Data were obtained from direct measurements in the field and on from the company's engine conditions records from 1991 to 2011. Data were analyzed with assessment of critical components (ECR) and optimization of time for component replacement (CoTR). The results showed that conveyors are the most critical components in the system of seed production machine maintenance. CoTR of the components are ranging from 0.87 to 3.14 years, and it can be implemented with scheduled replacement of 6 months, 1 year, 2 years and 4 years, respectively. There is also a need to improve the recording procedures of engine maintenance activities by PT Sang Hyang Seri which include the damage and the treatment carried out.
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Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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