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Makara Journal of Technology
Published by Universitas Indonesia
ISSN : 23552786     EISSN : 23564539     DOI : https://doi.org/10.7454/mjt
Core Subject : Science, Engineering,
Chemical Engineering, Chemistry & Bioengineering Civil Engineering, Building, Construction & Architecture Electrical & Electronics Engineering Engineering Materials Science & Nanotechnology Mechanical Engineering
MAKARA Journal of Technology is a peer-reviewed multidisciplinary journal committed to the advancement of scholarly knowledge and research findings of the several branches of Engineering and Technology. The Journal publishes new results, original articles, reviews, and research notes whose content and approach are of interest to a wide range of scholars. It also offers rapid dissemination. MAKARA Journal of Technology covers the recent research in several branches of engineering and technology include Electrical & Electronics Engineering, Computer Engineering, Mechanical Engineering, Chemical & Bioprocess Engineering, Material & Metallurgical Engineering, Industrial Engineering, Civil & Architecture Engineering, and Marine Engineering. Criteria used in determining acceptability of contributions include newsworthiness to a substantial part of the engineering & technology and the effect of rapid publication on the research of others. This journal, published three times each year, is where readers look for the advancement of discoveries in engineering and technology.
Arjuna Subject : Teknik (semua kategori) - Teknik (Lain-Lain)
Articles 7 Documents
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Search results for , issue "Vol. 19, No. 2" : 7 Documents clear
High Temperature Corrosion of Aluminized AISI 4130 Steel with the Different Composition of NaCl/Na2SO4 Deposits Badaruddin, Mohammad; Wang, Chaur Jeng; Saputra, Yudhistyra; Rivai, Abu Khalid
Makara Journal of Technology Vol. 19, No. 2
Publisher : UI Scholars Hub

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Abstract

The high temperature corrosion of AISI 4130 steel can be increased by hot-dip aluminizing coating. The aluminized steel specimens with the deposit composition of 100/0, 30/70, 50/50, 70/30, and 0/100 (wt.%) NaCl/Na2SO4 were oxidized at 750 °C for 1-49 h periods. According to a parabolic rate constant (kp) value, the aluminized steel with deposit composition of 70/30 NaCl/Na2SO4 shows the highest kp value (3.71 × 10-11 g2cm- 4s-1), later followed by the kp value of 3.35 × 10-11 g2cm-4s-1 for 100/0 and the lowest kp value is 7.731 × 10-12 g2cm-4s-1 for 0/100. Whereas, the kp value for the aluminized steel without NaCl/Na2SO4 deposit is around 2.23 × 10-13 g2cm-4s-1. The presence of both salts and their mixtures destroyed protective Al2O3 layer on the aluminized steel, leading to the Fe2O3 growth locally. Whereas, the penetration of sulfur into the Al2O3 scale lead to the formation of Al2S3 and FeS in the aluminide coating. Therefore, the kinetics rate was increased. Furthermore, mixtures of 70 wt. % NaCl in Na2SO4 depositing on the aluminized steel produced the highest parabolic rate constant because the aluminide layer on the steel substrate experienced severe corrosion attack, leading to fail in formation of protective Al2O3 layer.
Effects of Supplier-Manufacturer Relationships on Supply-Chain Performance of Manufacturing Industries in Indonesia Hidayat, Rachmad; Hudha, Khisbullah; Akhmad, Sabarudin
Makara Journal of Technology Vol. 19, No. 2
Publisher : UI Scholars Hub

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Abstract

The present study describes the relationships between commitment, communication, satisfaction, trust, relationship quality with suppliers, and supply-chain performance. The population of the study was manufacturing companies in Indonesia. Respondents were the chief executive officers or corporate secretaries or the designated managers involved in strategic decision making. Samples were taken by using a proportional area random sampling technique. Structural Equation Modeling (SEM) was used for analysis. Results of both direct and indirect testing of hypothesis indicated two hypotheses of positive and significant effects and nine hypotheses of positive but insignificant effects. Those hypotheses of positive and significant effects were the direct effects of trust on supply-chain performance and the direct effects of relationship quality on supply chain performance.
A New Method for Simulating Power Flow Density Focused by a Silicon Lens Antenna Irradiated with Linearly Polarized THz Wave Apriono, Catur; Rahardjo, Eko Tjipto; Hiromoto, Norihisa
Makara Journal of Technology Vol. 19, No. 2
Publisher : UI Scholars Hub

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Abstract

A terahertz system uses dielectric lens antennas for focusing and collimating beams of terahertz wave radiation. Linearly polarized terahertz wave radiation has been widely applied in the terahertz system. Therefore, an accurate method for analyzing the power flow density in the dielectric lens antenna irradiated with the linearly polarized terahertz wave radiation is important to design the terahertz systems. In optics, ray-tracing method has been used to calculate the power flow density by a number density of rays. In this study, we propose a method of ray-tracing combined with Fresnel’s transmission, including transmittance and polarization of the terahertz wave radiation to calculate power flow density in a Silicon lens antenna. We compare power flow density calculated by the proposed method with the regular ray-tracing method. When the Silicon lens antenna is irradiated with linearly polarized terahertz wave radiation, the proposed method calculates the power flow density more accurately than the regular ray-tracing.
Transmission Electron Microscopy Characterization of High-Temperatur Oxidation of Fe-20Cr-5Al Alloy Prepared by Focused Ion Beam Technique Dani, Mohammad; Untoro, Pudji; Putra, Teguh Yulius Surya Panca; Parikin, Parikin; Mayer, Joachim; Dimyati, Arbi
Makara Journal of Technology Vol. 19, No. 2
Publisher : UI Scholars Hub

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Abstract

The Focused Ion Beam (FIB) technique was applied for cross section preparation of the oxidized alloy for Transmission Electron Microscopy (TEM) study. Prior to preparation, the specimens of Fe-20Cr-5Al alloy sheet were oxidized in air at 1200 oC for 2 minutes, 10 minutes, 2 hours, and 100 hours. The microstructure and elemental composition of the samples were characterized using TEM equipped with an Energy Dispersive X-Ray Spectroscopy (EDX). The Electron Energy Loss Spectroscopy (EELS) was used to determine of the light elements. The TEM investigation reveals remarkable microstructure evolution of the specimens during oxidation which generally exhibit a typical multi-layer structure. The TEM images, however, can provide detailed description about the phases occur after oxidation such as the Tungsten (W) and the Gallium (Ga) layers on top of the samples obviously formed during FIB preparation, the formation of Al2O3 and Cr2O3 layer, MgAl2O4 spinel, porosity, Zr/Hf/Mg phases or clusters inside the oxide scale. Hence, the FIB technique has been proven to be reliable preparation technique for microstructural and elemental studies of Fe-20Cr-5Al alloy using TEM.
Application of Fiscal Incentives for Development of East Natuna Gas Field for Long-Term National Natural Gas Demand Batubara, Marwan; Purwanto, Widodo Wahyu; Fauzi, Akhmad
Makara Journal of Technology Vol. 19, No. 2
Publisher : UI Scholars Hub

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Abstract

East Natuna gas field, which has proven reserves of 46 trillion cubic feet, is projected to meet long-term natural gas needs. However, CO2-content of the gas reserves reaches 71%, leading to expensive development costs. This research investigates the feasibility of the field based on several fiscal incentives. Firstly, gas supply-demand until year 2040 was analyzed. Then, based on the analysis, the field was developed using high CO2 gas separation technology to produce gas of 1300 MMSCFD in 2023, 2600 MMSCFD in 2031, and 3900 MMSCFD in 2039. Finally, the economic feasibility was assessed using cash flow analysis in accordance with Indonesia’s production sharing contract scheme. The results show that the supply-demand gap continues to increase and thus the development is urgently needed. The development cost is estimated around US$ 27.59 billion. The gas selling prices are assumed at US$ 8/MMBTU for wellhead, US$ 11/MMBTU for pipelines, and US$ 11/MMBTU for LNG. To achieve minimum IRR value of 12%, the government needs to offer incentives of 30-year contract period, profit sharing of 55%: 45%, first tranche petroleum to 10%, and tax holiday of 10 years. Toll fee for Natuna-Cirebon pipeline is US$ 2.3/MMBTU at IRR of 12.6%.
Stochastic Optimization of Supply Chain Risk Measures –a Methodology for Improving Supply Security of Subsidized Fuel Oil in Indonesia Yuanita, Adinda; Sommeng, Andi Noorsaman; Wijonarko, Anondho
Makara Journal of Technology Vol. 19, No. 2
Publisher : UI Scholars Hub

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Abstract

Monte Carlo simulation-based methods for stochastic optimization of risk measures is required to solve complex problems in supply security of subsidized fuel oil in Indonesia. In order to overcome constraints in distribution of subsidized fuel in Indonesia, which has the fourth largest population in the world—more than 250,000,000 people with 66.5% of productive population, and has more than 17,000 islands with its population centered around the nation's capital only—it is necessary to have a measurable and integrated risk analysis with monitoring system for the purpose of supply security of subsidized fuel. In consideration of this complex issue, uncertainty and probability heavily affected this research. Therefore, this research did the Monte Carlo sampling-based stochastic simulation optimization with the state-of-the-art "FIRST" parameter combined with the Sensitivity Analysis to determine the priority of integrated risk mitigation handling so that the implication of the new model design from this research may give faster risk mitigation time. The results of the research identified innovative ideas of risk based audit on supply chain risk management and new FIRST (Fairness, Independence, Reliable, Sustainable, Transparent) parameters on risk measures. In addition to that, the integration of risk analysis confirmed the innovative level of priority on sensitivity analysis. Moreover, the findings showed that the new risk mitigation time was 60% faster than the original risk mitigation time.
Thermodynamic Analysis of Irreversible Heat-transformers Giannetti, Niccolo`; Arnas, Arnas; Rocchetti, Andrea; Saito, Kiyoshi
Makara Journal of Technology Vol. 19, No. 2
Publisher : UI Scholars Hub

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Abstract

Absorption heat transformers extend the possibilities for efficient and environment-friendly energy conversion processes. Based on a general thermodynamic model of three-thermal cycles with finite thermal capacity of the heat sources, this paper is intent upon analyzing and optimizing the performance of absorption heat transformers, by including the influence of irreversibility in the analytical expression of the system efficiency. Dimensionless parameters for an overall optimization are defined and a first screening is performed to clarify their influence. Dependence on the main factors is highlighted to suggest how to change them in order to enhance the whole system performance. Under this point of view, the analysis evaluates coefficient of performance (COP) improvements and can be used to perform existing plant diagnostics, besides predicting the system performance. The use of this criterion is exemplified for specific heat transformers data from literature. This approach identifies the limitations imposed to the physical processes by accounting for the inevitable dissipation due to their constrained duration and intensity, and constitutes a general thermodynamic criterion for the optimization of three-thermal irreversible systems.

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