Judul: Development Strategy for Drinking Water Supply System in the Concentrating Division Area (Mile 74) PT. Freeport Indonesia
Abstrak: The Concentrating Division is one of the operational divisions within PT Freeport Indonesia (PTFI). With the number of employees of ± 1600 employees based on manpower data in 2020.In supporting safe and secure operations,an improvement in the quality of service to employees is needed in terms of the need for safe and healthy drinking waterAlong with the Circular No.704/37.04/DBT/2019 concerning the Prohibition of the Use of Disposable Plastic Drinking Water Packaging and/or Plastic Bags in the Mining Work Environment,a strategy is needed in the drinking water supply system and provides improvements to the quality of the environment by not using bottled drinking water.This study aims to assess employee perceptions of theimplementation of the drinking water supply system, especially the Concentrating division, analyze the costs incurred by the company and then formulate a strategy for developing SPAM in the concentrating division of PTFI. This research uses the methodqualitative and quantitative approach. In the quantitative approach, it is done by collecting various information and studying literature on several previous studies.The qualitative approach process is obtained by collecting data in the field, either primarydata or secondary data, from interviews with experts or experts in the field of drinking water management, and taking company reports related to the spending of the Concentrating division related to drinking water supply. The results of the assessment given to respondents from the questionnaire with the highest rating weight are with point 4 where employee perceptions state 38.22% of respondents stated that the change in the drinking water management system (SPAM) is good (B).Based on the results of the calculation of the cost of AMDK spending and SPAM investment per year the value of SPAM development investment < bottled water(AMDK)spending.The investment cost in the construction of SPAM in the area of the 74 Concentrating Mile Division is also a combined management unit for supplying clean water needs.Calculation of the analytical hierarchy process (AHP) the most dominant factor in the assessment by experts The results obtained from the expert's assessment of an appropriate alternative in the drinking water supply system development strategy obtained the best alternative in the Drinking Water Supply System(SPAM)Development Strategy in the Region Concentrating Division (Mile 74) PT. Freeport Indonesia is developing a controlled drinking water management system with a rating weight of 0.323.
Keyword: AHP, AMDK, Concentrating Divison, PTFI dan SPAM

Judul: Masalah pemanfaatan air bawah tanah bagi Perusahaan Air Minum dalam kemasan : studi kasus di PT Tang Mas Cidahu Sukabumi
Abstrak: Water is a class of renewable natural resources. The main source of water is the rain that will always come during its season along the year. The water flows and moves (on the ground and underground) and then will stay at a retention (storage) area. There are two kinds of the retention that are i) natural retention (such as concave areas, lake, and low places) and ii) artificial retention (such as saving water, well, and basin). The presence of the river basin in a region will affect the availability of water resources. A region which has river basin could use ground water resources to fulfill the water requirements for household, agriculture, industries, tourism, and electric power station sectors. A manufacturing of drinking water in packing (AMDK) is normally built around a river basin area so that it can use the resource of water from the spring. But a problem would arise whenever the manufacture decide to increase the production capacity. This research addressed the problem of determining an optimal composition on water resources for AMDK manufacturing in order to minimizing the total cost. Each water resource alternative has different cost characteristics. The cost can be classified to fixed and variable cost. This problem is modeled as an integer linear programming problem and solved using branch and bound method via LINGO 8.0 software. This model is implemented at PT Tang Mas Cidahu in Kampung Bojong Pari Desa Jaya Bakti Kabupaten Sukabumi, West Java.
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Judul: Penentuan Nilai Eigen dan Vektor Eigen dari Matriks Tridiagonal 2-Toeplitz dengan Pendekatan Polinomial Chebyshev
Abstrak: The eigenvalues and eigenvectors of a matrix can be determined by finding its characteristic polynomials. The characteristic polynomials of a tridiagonal 2-Toeplitz matrix is shown to be closely connected to polynomials which satisfy the Chebyshev recurrence relationship. If the order of the matrix is odd, then the eigenvalues are found explicitly in terms of the Chebyshev zeros and the eigenvectors are found in terms of the polynomials satisfying the recurrence relationship. For even ordered matrices, the situation is more complicated. The problem in these cases is that although the Chebyshev recurrence formula is still applied, its initial values are not generating Chebyshev polynomials
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