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: Energy Management System Implementation Strategy at PT Freeport Indonesia’s Concentrating Divion based on ISO 50001:2018
Abstrak: Energy is one of the basic human needs that support all activities. The entire system and dynamics of human and state life depend on energy as the lifeblood of all sectors, resulting in world energy consumption increasingevery year in line with the development of human civilization. so that energy must be managed and utilized properly and efficiently. The Government of Indonesia regulates energy management through PPNo.70 of 2009 and Minister of Energy and Mineral Resources Regulation No. 14 of 2012 concerning energy management, which in this regulation emphasizes all users of energy sources and energy users who use energy greater than or equal to 6,000 tons of oil equivalent (TOE) are required to carry out energy management. PT Freeport Indonesia (PTFI) as an energy user in mining operations in Indonesia is required to implement an energy management system because it uses energy more than 6000 TOE. Based on this background, the objectives of this study are: (1) to analyze the current level of implementation of the energy management system that has been carried out by the PTFI Concentrating Division; (2) analyze the comparison of the Concentrating Division's energy management system with the ISO 50001:2018 standard; and (3) formulate a strategy for implementing an energy management system according to the ISO 50001:2018 standard at the PT Freeport Indonesia Concentrating Division processing plant. The method in this study uses gap analysis (gap and IPA) and analytical hierarchy process (AHP). The primary data was obtained from interviews and questionnaires by six respondents from the energy management system expert in the Concentrating Division, while the secondary data came from audit reports and PTFI internal data. The research was conducted at PTFI's concentrate processing plant from June to September 2022. The implementation strategy is formulated based on the results of a comparison of the performance level of the energy management system with the 7 clauses of ISO 50001:2018 and their level of importance. The results obtained are 7 clauses that do not meet the standards and 3 clauses of which have a high level of importance but low performance levels to be handled with four different strategies:(1) conducting internal audits and external energy audits; (2) energy management system training; (3) carrying out activities energy efficiency-oriented production;and (4) using automation systems and technology on equipment.
Keyword: AHP, Concentrate Processing Plant, Energy Management System, Gap Analysis, ISO 50001:2018

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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