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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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Physical Characterization and Desulfurization of Biobriquette Using Calcium-Based Adsorbent Mahidin, Mahidin; Gani, Asri; Khairil, Khairil
Makara Journal of Technology Vol. 15, No. 2
Publisher : UI Scholars Hub

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Abstract

Combustion of coal and co-combustion of their co-fuel contribute to gas emissions. Among the gas emissions are SOx, NOx, CO and CO2. Introduction of calcium based adsorbent is addressed to absorb SO2 that release to the atmosphere during the combustion process. Objective of the research is at first to observe the physical characteristics of biobriquettes as a function of briquette compositions (coal to palm kernel shell ratios) and Ca/S ratios (Ca in adsorbent and S in briquette) using a natural adsorbent (shellfish waste). The second objective is to investigate desulfurization characteristics as a function of Ca/S ratios and desulfurization temperatures at coal to palm kernel shell ratio of 90:10 (wt %). Ratios of coal to palm kernel shell in this study are 90:10, 80:20, 70:30, 60:40 and 50:50; and Ca/S ratios are 1:1, 1.25:1, 1.5:1, 1.75:1 and 2:1. Binding agent used is the mixture of Jatropha curcas seeds and starch as much as 10% (wt). It was found that introducing the palm kernel shell and adsorbents in the coal briquette affect the water resistant and compressive strength. The highest water resistance and compressive strength were 5,165 second and 34 kg/cm2, respectively. The lowest SO2 level found in this study was 1 ppm for all Ca/S ratios, except for 1:1.
Cassava Pulp as a Biofuel Feedstock of an Enzymatic Hydrolysis Proces Djuma’ali, Djuma’ali; Soewarno, Nonot; Sumarno, Sumarno; Primarini, Dyah; Sumaryono, Wahono
Makara Journal of Technology Vol. 15, No. 2
Publisher : UI Scholars Hub

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Abstract

Cassava pulp, a low cost solid byproduct of cassava starch industry, has been proposed as a high potential ethanolic fermentation substrate due to its high residual starch level, low ash content and small particle size of the lignocellulosic fibers. As the economic feasibility depends on complete degradation of the polysaccharides to fermentable glucose, the comparative hydrolytic potential of cassava pulp by six commercial enzymes were studied. Raw cassava pulp (12% w/v, particle sizeμm) hydrolyzed by both commercial pectinolytic (1) and amylolytic (2) enzymes cocktail, yielded 70.06% DE. Hydrothermal treatment of cassava pulp enhanced its susceptibility to enzymatic cleavageas compared to non-hydrothermal treatment raw cassava pulp. Hydrothermal pretreatment has shown that a glucoamylase (3) was the most effective enzyme for hydrolysis process of cassava pulp at temperature 65 °C or 95 °C for 10 min and yielded approximately 86.22% and 90.18% DE, respectively. Enzymatic pretreatment increased cassava pulp vulnerability to cellulase attacks. The optimum conditions for enzymatic pretreatment of 30% (w/v) cassava pulp by a potent cellulolytic/ hemicellulolytic enzyme (4) was achieves at 50 °C for 3, meanwhile for liquefaction and saccharification by a thermo-stable α-amylase (5) was achieved at 95 °C for 1 and a glucoamylase (3) at 50 °C for 24 hours, respectively, yielded a reducing sugar level up to 94,1% DE. The high yield of glucose indicates the potential use of enzymatic-hydrothermally treated cassava pulp as a cheap substrate for ethanol production.
ALOS/PALSAR Image Processing Using Dinsar and Log Ratio for Flood Early Detection in Jakarta Based on Land Subsidences Sudiana, Dodi; Rizkinia, Mia
Makara Journal of Technology Vol. 15, No. 2
Publisher : UI Scholars Hub

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Abstract

Flood that occurred in Jakarta is not only influenced by rainfall, urban planning system and drainage alone, but also may be involved land subsidence (LS). LS is possible in because Jakarta stands on top of layers of sediments and the presence of ground water consumption in very large quantities. In this research, the Advanced Land Observing Satellite (ALOS)/Phased Array type L-band Synthetic Aperture Radar (PALSAR) data was processed to determine the level of LS in Jakarta area and its relation to flood potential area. Differential interferometry method (DInSAR) was performed on two PALSAR data with different acquisition years, i.e. 2007 and 2008, respectively. DInSAR processing generated images containing information that can be converted into LS. To find the elevation changing area, log ratio algorithm was applied to those images as the additional analysis. The log ratio image is superimposed on the DInSAR result and Jakarta inundation map of 2009, to acquire the relationship between LS and the flood and flood vulnerability map of Jakarta based on LS. It is found that lands on the flooded area of 10.57 cm on the average, with a minimum and maximum of 5.25 cm and 22.5 cm, respectively. The greater the value of LS, inundation area also tend to widen, except in a few areas that have special conditions, such as reservoirs, river flow solution, water pump system and sluices. Accuracy of DInSAR result image is quite high, with the difference of 0.03 cm (0.18%) to 0.55 cm (3.37%) as compared to those from GPS measurements. These results can be recommended to the local government of Jakarta to minimize the potential risk of flood, as well as the subject of city planning for the future.
Concurrent Engineering of Tolerance Synthesis and Process Selection for Products with Multiple Quality Characteristcs Considering Process Capability Mustajib, Mohamad Imron
Makara Journal of Technology Vol. 16, No. 1
Publisher : UI Scholars Hub

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Abstract

The existences of variances that are very difficult to be removed from manufacturing processes provide significance of tolerance to the product quality characteristics target of customer functional requirement. Furthermore, quality loss incurred due to deviation of quality characteristics of the target with a specified tolerance. This article discusses the development of concurrent engineering optimization model of tolerance design and manufacturing process selection on product with multiple quality characteristics by minimizing total costs in the system, namely total manufacturing cost and quality loss cost as functions of tolerance, also rework and scrap costs. The considered multiple quality characteristics have interrelated tolerance chain. The formulation of proposed model is using mixed integer non linear programming as the method of solution finding. In order to validate of the model, this study presents a numerical example. It was found that optimal solution are achieved from proposed model in the numerical example.
Evaluation of Universitas Indonesia’s Recharge Pond Performance and Potential Utilization for Raw Water Source Suwartha, Nyoman; Pramadin, Resky Agaslian
Makara Journal of Technology Vol. 16, No. 1
Publisher : UI Scholars Hub

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Abstract

Evaluasi Kinerja Waduk Resapan UI dan Potensi Pemanfaatannya sebagai Sumber Air Baku. Waduk resapan Universitas Indonesia (UI) telah dibangun sejak 5 tahun yang lalu. Namun kegiatan monitoring dan evaluasinya sangat minim dilakukan. Tujuan dari studi ini adalah untuk mengetahui laju resapan, dan untuk mengevaluasi kondisi kuantitas dan kualitas air waduk resapan selama musim kemarau dan penghujan. Pengukuran kedalaman muka air, intensitas curah hujan dan penguapan dilakukan untuk menentukan ketersediaan air, laju resapan, dan imbangan air waduk. Sejumlah air permukaan diambil dari waduk resapan dan sungai di tiga titik sampling untuk mengetahui kondisi kualitas air eksisting. Hasil studi menunjukkan tidak ada perbedaan yang signifikan antara laju resapan musim kemarau (3,2 mm/hari) dan musim penghujan (6,1 mm/hari). Imbangan air waduk resapan menunjukkan nilai yang berlimpah. Berbagai parameter fisik dan kimia air (kekeruhan, warna, TDS, pH, dan Cl) mempunyai konsentrasi di bawah standar baku mutu. Temuan dari studi ini antara lain bahwa air permukaan waduk masih layak untuk diimbuhkan ke dalam lapis aquifer sehingga mendukung keberlanjutan gerakan konservasi air, dan ketersediaannya sangat berpotensi untuk dikembangkan sebagai sumber air baku tambahan bagi kebutuhan air domestik di lingkungan Kampus UI Depok.
Modification of Flow Structure Over a Van Model By Suction Flow Control to Reduce Aerodynamics Drag Harinaldi, Harinaldi; Budiarso, Budiarso; Warjito, Warjito; Kosasih, Engkos Achmad; Tarakka, Rustan; Simanungkalit, Sabar Pangihutan; Lay Teryanto, I Gusti Made Fredy
Makara Journal of Technology Vol. 16, No. 1
Publisher : UI Scholars Hub

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Abstract

Automobile aerodynamic studies are typically undertaken to improve safety and increase fuel efficiency as well as to find new innovation in automobile technology to deal with the problem of energy crisis and global warming. Some car companies have the objective to develop control solutions that enable to reduce the aerodynamic drag of vehicle and significant modification progress is still possible by reducing the mass, rolling friction or aerodynamic drag. Some flow control method provides the possibility to modify the flow separation to reduce the development of the swirling structures around the vehicle. In this study, a family van is modeled with a modified form of Ahmed's body by changing the orientation of the flow from its original form (modified/reversed Ahmed body). This model is equipped with a suction on the rear side to comprehensively examine the pressure field modifications that occur. The investigation combines computational and experimental work. Computational approach used a commercial software with standard kepsilon flow turbulence model, and the objectives was to determine the characteristics of the flow field and aerodynamic drag reduction that occurred in the test model. Experimental approach used load cell in order to validate the aerodynamic drag reduction obtained by computational approach. The results show that the application of a suction in the rear part of the van model give the effect of reducing the wake and the vortex formation. Futhermore, aerodynamic drag reduction close to 13.86% for the computational approach and 16.32% for the experimental have been obtained.
Age, Gender, and Muscle Strength: a Study Based on Indonesian Samples Henny, Henny; Iridiastadi, Hardianto; Sutalaksana, Iftikar Zahedi
Makara Journal of Technology Vol. 16, No. 1
Publisher : UI Scholars Hub

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Abstract

Age and gender have been commonly used as a main criterion in accepting a job aplicant, but it is usually not clear how these affect job performance. While a number of recent studies have been done that describe the relationships between age, gender, and participants capacity (e.g., muscle strength), the results have been inconclusive. In Indonesia, in particular, such issues have been rarely investigated, and it is still important to study the issue since the relationships between these factors are population-specific. This study aimed at describing the relationships between age and muscle strength among workers for both genders. Ninety-six male and female workers (aged 18–65) were recruited in this study, and data on handgrip and lower back strength were collected. Findings of this study show that peak hand-grip strength occured at the age of around 35-40 years of age, regardless of gender. Maximum lower back strengh was identified at the age of 31-35 years old (for males) and 26-30 years old (for females). Comparisons between two extreme age groups (18-20 vs. 61-65 years of age) showed a mean strength decline of 50% for hand-grip and 30% for the lower back. For both protocols, female participants tended to have lower muscle strength (70-80% of their male counterparts). Findings of this study can be used as a basis in evaluating physical requirements of a job, and the corresponding factors (age and gender) relevant for the job.
Effect of Methanol Induction and Incubation Time on Expression of Human Erythropoietin in Methylotropic Yeast Pichia Pastoris Santoso, Adi; Herawati, Neng; Rubiana, Yana
Makara Journal of Technology Vol. 16, No. 1
Publisher : UI Scholars Hub

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Abstract

Erythropoietin (EPO) is a glycoprotein hormone consists of 165 amino acids and has molecular mass of 30,400 Daltons. The large quantities of these hormone required to satisfy clinical demand are currently met by recombinant expression in mammalian cell, namely chinese hamster ovary (CHO). Pichia pastoris has become popular yeast based protein production systems to substitute mammalian expression systems. P. pastoris is capable to use methanol as sole carbon and energy source. In this study, recombinant human EPO (rhEPO) protein obtained by expressing the hEPO gene in methylotropic yeast P. pastoris, strain X33. The present work was carried out to study the optimal methanol concentration for induction and the incubation time to obtain rhEPO protein. To perform this study, the transformed P. pastoris was induced with various concentrations of methanol (0%, 0.5%, 1%, 2.5%, 5%, 10%, and 20%) and incubation times (0 hours, 24 hours, 48 hours, 72 hours, 96 hours, 120 hours, and 144 hours). The results demonstrate that the highest protein expression level occurred at concentration of 2.5% methanol induction, while the optimal incubation time was at 48 hrs.
Fuel Saving Strategy in Spark Ignition Engine Using Fuzzy Logic Engine Torque Control Triwiyatno, Aris; Sumardi, Sumardi
Makara Journal of Technology Vol. 16, No. 1
Publisher : UI Scholars Hub

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Abstract

In the case of injection gasoline engine, or better known as spark ignition engines, an effort to improve engine performance as well as to reduce fuel consumption is a fairly complex problem. Generally, engine performance improvement efforts will lead to increase in fuel consumption. However, this problem can be solved by implementing engine torque control based on intelligent regulation such as the fuzzy logic inference system. In this study, fuzzy logic engine torque regulation is used to control the throttle position entered by the driver to achieve optimal engine torque. An engine torque vs. throttle position and engine speed mapping for vehicles with economical function is used to build this control process regulation. From the simulation result, it can be concluded that this control strategy is very effective to reduce fuel consumption and simultaneously to optimize the engine performance.
An Agri-Food Supply Chain Model to Enhance the Business Skills of Small-Scale Farmers Using Corporate Social Responsibility Sutopo, Wahyudi; Hisjam, Muh.; Yuniaristanto, Yuniaristanto
Makara Journal of Technology Vol. 16, No. 1
Publisher : UI Scholars Hub

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Abstract

In general, small-scale vegetable farmers experience problems in improving the safety and quality of vegetables for supplying high-class consumers in modern retailers. Farmer Group and/or Cooperative (FGC) should be able to assist its members to meet the relevant provisions of modern retail on product specifications, delivery terms, and internal business requirements. This study proposed an agri-food supply chain (ASC) model that involves the corporate social responsibility (CSR) activities to enhance the business skills of the FGC as supplier of modern retailer. Multi-objective optimization programming is developed to determine the amount and timing of supply, level of farmers training skills, quality improvement target, and the CSR total cost. The results show that the proposed model can be used to determine the priority of programs in order to empower farmers' groups as modern retail suppliers.

Page 20 of 49 | Total Record : 485

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