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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 485 Documents
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Economic Design, Fabrication, and Performance Evaluation of Conventional Ovens Made of Glass-Fiber-Reinforced Thermoset Composites Anayo Agbo, Cornelius Ogbodo
Makara Journal of Technology Vol. 25, No. 3
Publisher : UI Scholars Hub

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Abstract

This study focuses on the development of a conventional oven using glass-fiber-reinforced thermoset composite sandwich panels. The design process considers the thermomechanical properties of the selected materials. The constructed rectangular box oven has the overall dimensions of 450 mm × 450 mm × 600 mm and internal heat chamber dimensions of 400 mm width, 400 mm depth, and 400 mm height with two stack trays for product placement. The sidewalls consist of inner and outer E-glass-fiber-reinforced composite panels with a sandwiched rockwool insulator. The bottom panel of the oven has an inner ceramic tile plate to suspend the electric heating element. The top panel is made of the same composite sandwich with a constructed superstructure electrical wiring compartment included for the controls. The oven can stably achieve a temperature of 150 ℃ and a cooking efficiency of approximately 39% when in operation and can sustain heat for more than 6 h standing time when turned off. The oven can be used for both culinary and laboratory experiments, i.e., heating, baking, drying, and curing materials, and is more affordable than alternative designs in the market.
Assessing the E-learning Readiness of Universities in Developing Countries and Expected Obstacles Ate, Abdelrahim; Zaineldeenc, Samar; Zhaohui, Cai; Zhao, Yan
Makara Journal of Technology Vol. 25, No. 3
Publisher : UI Scholars Hub

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Abstract

To benefit from electronic learning (E-learning), organizations should execute considerable upfront analysis to ascertain their E-learning readiness. Studies have demonstrated a range of models that have been adapted, but they are used in developed counties for whom E-learning readiness is elevated. Thus, these models are not valid in growing countries, such as Sudan. Based on a modified model, this research was performed descriptively by applying a questionnaire-based survey method to assess the level of Sudan universities’ readiness in the employment of the E-learning system. This modified model includes social support, technology readiness, attitude toward E-learning, acceptance of E-learning, and individual learners. Furthermore, the adoption and implementation of E-learning involve numerous challenges and constraints. Therefore, in this study, the challenges that could be faced in applying E-learning in Sudan from students’ perspectives are investigated. The results show that the most prepared factor is individual learners at Sudanese universities. However, this factor still needs a few improvements for E-learning with an overall mean (3.59). Given that the learners are willing to collaborate and share information and knowledge, they can manage time for their learning, and they are also motivated and enthusiastic about using computers. Moreover, attitude toward E-learning is the least prepared factor among all factors (mean = 3.16), which means that this factor is not ready and needs some work. The study recognizes serious barriers that constrain the effective incorporation of E-learning in higher education institutes (HEIs) in developing countries.
Identification of Thermophilic Bacteria from Tirta Lebak Buana Hot Spring in Serang, Banten, Indonesia Lischer, Kenny
Makara Journal of Technology Vol. 25, No. 3
Publisher : UI Scholars Hub

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Abstract

Since Taq polymerase was first explored and identified from thermophilic bacteria, these bacteria have become well-known sources of thermostable enzymes. New thermophilic bacteria have been investigated to broaden biodiversity and translation research. Studies have shown interests in Indonesia because of thermophilic bacteria found in hot springs. This country is traversed by the ring of fire and has more than 70 volcanoes, resulting in the wide distribution of hot springs across the country. Although many reports have been performed, studies have yet to explore thermophilic bacteria in Tirta Lebak Buana hot springs, Java Island, Indonesia. This research was the first to examine thermophilic bacteria in Tirta Lebak Buana hot spring. Two samples from two different sampling sites were obtained and analyzed through 16srRNA analysis (sampling sites A and B). Measurements indicated that the temperature (50 °C) in sampling site A was higher than that in sampling site B (40 °C), but they had similar pH (7.0). Polymerase chain reaction (PCR) showed that the 16srRNA of the specimen was around 1465 bp. The analysis of the 16srRNA sequence revealed that the obtained bacteria have a similar sequence and close relationship with Bacillus subtilis subsp. stercoris strain N12.
Comparative Study of Rankine Cycle Power Generation using Water and Organic Fluids in Saturated and Superheated States Pikra, Ghalya; Sudibyo, Henny
Makara Journal of Technology Vol. 25, No. 3
Publisher : UI Scholars Hub

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Abstract

The Rankine cycle is an electricity generation system that uses water or organic fluids as high-grade or low-grade heat sources, respectively. In this paper, we present the results of our study of Rankine-cycle power generation in which we compared water and organic fluids (toluene and n-nonane) as working fluids in saturated and superheated states. We analyzed the energy and exergy of the Rankine cycle in a saturated vapor state at 300 °C and superheated states at 400 °C and 500 °C (the pressure remained the same as that at 300 °C), and assumed a constant heat input for all states. In the energy analysis, we determined the mass flow rate, heat rejection, work input of the pump, work generated by the turbine, net work output, and thermal efficiency. In the exergy analysis, we determined the exergy input, exergy loss, exergy destruction at the pump and the turbine, and the exergetic efficiency. The results show that water, categorized as a wet fluid, obtains a better performance with respect to both analyses in saturated and superheated states than toluene and n-nonane, which are categorized as isentropic and dry fluids, respectively. The water realizes a higher performance in the superheated than in the saturated state, whereas the performances of toluene and n-nonane are poorer in the superheated than in the saturated state.
Analysis of the Interfacial Reaction between Bulk Metallic Glass Coated Copper, Nickel, and Titanium with Lead-Free Solders Laksono, Andromeda Dwi; Yen, Yee-wen; Tanjung, Rifqi Aulia; Amatosa, Teodoro A.; Harwahyu, Ruki
Makara Journal of Technology Vol. 25, No. 1
Publisher : UI Scholars Hub

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Abstract

Bulk metallic glass (BMG) has good mechanical strength, high hardness, wear resistance, and corrosion resistance with promising application in various industries. However, for the industrial production of BMG, the main issue is how to overcome limitations of joining with other materials. The present study focuses on solder processing at low operating temperature to avoid exceeding the recrystallization temperature. A feasible joining process for BMG was developed using lead-free solders. The BMG surface is pre-plated with copper, nickel, or titanium as a wetting layer. The reaction temperature is set between the glass transition temperature of BMG and the melting point of the solder. After a reflowing and aging process, the joint sample was examined using SEM, EDS, EPMA, and XRD. The Cu–Zr based BMG can be successfully joined with Sn-58Bi solder after plating Cu on the BMG surface. A diffusion layer was observed and the thickness increased with longer aging time. The main components of the diffusion layer are ZrO2 and Cu10Zr7.
Identification of The First Limiting Amino Acid In Cooked Polished White Rice Fed To Weanling Holtzman Rats Masrizal, Mellova; Lamb, J. B.
Makara Journal of Technology Vol. 7, No. 3
Publisher : UI Scholars Hub

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Abstract

Forty-eight male weanling rats (91 g) were utilized to study the nutritional adequacy of cooked polished white rice. Rats were individually housed, and allowed ad libitum access to one of six treatment diets. Treatment diets were 1) polished white rice plus 10% casein and 0.18% methionine, CAS, 2) polished white rice, WHR, 3) polished white rice plus 0.45% lysine, LYS, 4) polished white rice plus0.40% methionine, MET, 5) polished white rice plus 0.30% threonine, THR, 6) polished white rice plus 0.45% lysine, 0.40% methionine, and 0.40% threonine, COM. Rice was cooked prior diet formulation using a 3 to 1 ratio of water to rice. Vitamins (AIN-76) and AIN minerals were added to all diets to meet NRC (1978) requirements. Rats fed CAS diets were significantly heavier on d 21 (P0.05) rat performance over WHR fed rats, Average daily gain (ADG) for CAS was 6.1 g/d and ADG for LYS and MET was 3.0 g/d. The addition of threonine (THR) significantly (P
Analysis of Kancil's Car Knuckle Prototype Soemardi, Tresna P.; Mahmudah, Aida
Makara Journal of Technology Vol. 8, No. 1
Publisher : UI Scholars Hub

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Abstract

Analysis of Kancil’s Knuckle Prototype. The objective of this work is to execute strength analysis of knuckle, which is made from FCD 50, by using static analysis on maximum loading. This maximum loading is obtained from front axle loading calculation on particular operating condition. That is, vehicle is braking while cornering in down hill. From previous vehicle loading calculation, we get a number of loading values on different speed and deceleration. At the end, we get a value of speed and deceleration that guarantee the vehicle safety if it is braking while cornering in down hill. As comparison, loading calculation is executed too for same operating condition on level ground. This is because of different deceleration for each operating condition, 0,5g for operating condition on downhill and 0,2g on level ground. The result shows that maximum loading occurred when vehicle is operated on down hill is larger than on level ground. Study of static focused on quantitative description of loads that act on technical structure in equilibrium.
Effects of Plasma Sintering on the Post TIG Weld Joint of Fe-15Cr-25Ni Austenitic Stainless Steel Parikin, Parikin; Dani, Mohammad; Dimyati, Arbi; Insani, Andon; Deswita, Deswita; Aziz, Ferhat; Mardiyanto, Mardiyanto; Mustofa, Salim; Purwanto, Setyo; Adhika, Damar Rastri; Syahbuddin, Syahbuddin; Huang, Ching An
Makara Journal of Technology Vol. 26, No. 1
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Abstract

Arc-plasma sintering (APS) for 5 s has been applied to the post tungsten inert gas (TIG) weld joint of Fe–15Cr–25Ni austenitic stainless steel (ASS). The treatment is intended to observe the effect of heat generated by plasma on micro-crystal structures around the fusion zone (FZ), especially internal stress relief in steel after being subjected to welding. The effect of stress relief in weld was measured using the neutron diffraction technique. ASS that is predominantly composed of Fe, Cr, and Ni elements, with contents of 57%, 15%, and 25%wt. respectively, was cut into two parts. Both parts were then welded with TIG without filler with a current and voltage of 60 A and 50 V, respectively. After APS for 5 s, the sample was characterized and analyzed using high-resolution powder neutron diffractometer at a high-temperature laboratory facility. The results show that the tensile residual stress decreased with the APS heat input. The residual stresses significantly decreased from 82.40 MPa to 1.21 MPa in the FZ and continued almost evenly from 65.92 MPa to 1.24 MPa in the heat-affected zone (HAZ). The residual stress is a tensile stress that can reduce the mechanical strength of materials. This condition is also applicable to applied loads. A microstructure gives a confirmation that the C element migrates from the FZ to HAZ. The content was very high in dark traces. The C element reacts to Cr and O to form chromium carbide (Cr23C6) and chromium carbonyl (CrC6O6), respectively. It rapidly migrates among its grain boundaries. It may also weaken materials and probably initiate intergranular cracks.
New In-situ Heating Apparatus Setup for Universal Testing Machine Algarni, Mohammed
Makara Journal of Technology Vol. 26, No. 2
Publisher : UI Scholars Hub

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Abstract

This paper presents a novel idea of establishing a low cost and highly efficient heating apparatus. This apparatus can be used along with any universal testing machines (UTM) for various tests, such as fracture, fatigue, torsion, and shear. This low cost and highly efficient option for researchers in solid mechanics may be used in a broad range of promising research areas. Moreover, this novel apparatus is beneficial for all researchers interested in high-temperature solid mechanics and applications. An extensive literature review presented reveals the existing heating apparatus currently used in mechanical testing labs globally, along with their pros and cons. A comparative study of the new heating apparatus and the current ones shows the advantages of the new heating apparatus and reveals how it overcomes the drawbacks of the existing heating apparatuses. The setup and connection of the new heating apparatus illustrate its secure operation and its easy commercial acquisition.
Three-phase AC Induction Motor Speed Control Based on Variable Speed Driver mohammed, abdelrahim ahmed, ate; Gafar, Rihab; Sun, Xiuyun; Abozead, Tahleel
Makara Journal of Technology Vol. 26, No. 2
Publisher : UI Scholars Hub

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Abstract

Massive loss of power is a concern for many countries because of the high power consumption of alternating current (AC) motors. The motor speed should be controlled to alleviate this problem and save more power. This paper proposes a simple simulation for a variable speed driver (VSD) to control the three-phase induction motor speed. The VSD consists of three parts. The converter performs from full bridge diodes to convert single-phase AC voltage into direct current voltage, and then this voltage is filtered by the RL filter and transferred to the last part, which is the inverter. The model was simulated by using MATLAB/Simulink. Findings show that the VSD controller provides sufficient control over the AC induction motor speed.

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