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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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Performances of Free-Space Optical Communication System Over Strong Turbulence Darusalam, Ucuk; Priambodo, Purnomo Sidi; Sudibyo, Harry; Rahardjo, Eko Tjipto
Makara Journal of Technology Vol. 18, No. 1
Publisher : UI Scholars Hub

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Abstract

We report an experimental of free-space optical communication (FSOC) system that use tube propagation simulator (TPS) as the turbulence medium. The FSOC system use wavelength of 1550 nm at the rate transmission of 1000 Mbps and amplified with EDFA at the output of +23 dBm. Index structure of 10-15–10-13 as the representation of atmosphere index turbulences are used for simulation of intensity distribution model or scintillation. The simulation use gammagamma and K model as well. The beam wave propagation models used in simulation are plane wave, spherical wave and Gaussian wave. Spherical wave achieves highest performance via gamma-gamma in strong turbulence. While Gaussian wave achieves highest performance also via K model. We also found, characteristical FSOC system performance is calculated more accurately with gamma-gamma method for strong turbulence than K model. The performances from gamma-gamma for strong turbulence are at 22.55 dB, at 5.33´10-4, and at 9.41 ´10-6.
Preparations of Nanostructured Silicide Bundles and Oxide Arrays Tatsuoka, Hirokazu; Li, Wen; Meng, Erchao; Ishikwa, Daisuke; Nakane, Kaito; Oda, Shingo; Matsushita, Tomoji; Kurebayashi, Natsuki
Makara Journal of Technology Vol. 18, No. 1
Publisher : UI Scholars Hub

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Abstract

A variety of nanostructured silicide bundles and oxide nanowire arrays with abundant, non-toxic materials we are prepared. The CrSi2 nanowire and Mg2Si/MgO composite nanowire bundles were synthesized using a Si substrate and a SiOx nanofiber bundle, respectively. The hexagonal MoSi2 nanosheet bundles were also synthesized using a MoS2 layered material as a template. In addition, ZnO, CuO/Cu2O and a-Fe2O3 nanowire arrays were prepared on semiconductor or metallic substrates. The growth phenomena and the structural properties of the nanostructured materials awere investigated. In addition, the preparations of axial and radial nanowire structures weare examined.
Bioethanol Production from Iles-Iles and Sorghum Starch as Raw Materials (Effect of CaCl 2 Addition and Saccharification Time) Kusmiyati, Kusmiyati; Mahmudi, Ali
Makara Journal of Technology Vol. 18, No. 1
Publisher : UI Scholars Hub

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Abstract

Bioethanol produced from agricultural sources is one alternative energy that has been developed to substitute for petroleum. However, the use of food sources such as corn and cassava to produce bioethanol still face obstacles that lead to the scarcity of food and an increase in food prices. The aim of this study was to produce bioethanol from sorghum and iles-iles, which are not used by humans as food, especially in Indonesia. For both materials, the variables studied were saccharification time (4, 8, 24, and 48 h) and concentration of CaCl2 added to the liquefaction slurry (0, 100, 200, 300, and 400 mg/L). The bioethanol was produced by enzymatic hydrolysis, which consists of liquefaction usinga-amylase at 1.6% v/w (t = 1 h; T = 95-100 °C; pH 6) and saccharification of the liquefaction slurry by using b- amylase at 3.2% v/w (t = various; T = 60 °C; pH 5) and fermentation by Saccharomyces cerevisiae (t = 120 hours; pH 4, 5; yeast 5g). The best conditions were obtained for sorghum at saccharification t = 24 h, which resulted in the highest ethanol yield, 91.5 g/L, and for iles-iles at t = 48 h, which yielded 107.1 g/L. The optimum amount of CaCl2 to be added was 200mg/L, which resulted in the highest ethanol yield, 98.5 g/L and 92.4 g/L for sorghum and iles-iles, respectively. This results shows that sorghum and iles-iles are promising raw materials for the production of bioethanol, since they produce it in large amounts.
The Effect of Zephyr Layer Orientation on Zephyrboard Made from Oil Palm Petiole Wardani, Lusita; Massijaya, Muhamad Yusram; Hadi, Yusuf Sudo; Darmawan, I Wayan
Makara Journal of Technology Vol. 18, No. 1
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Abstract

It is very important to utilize oil palm petiole for the production of zephyr boards. This study aimed to analyze the effect of layer orientation on zephyr board quality. Zephyr boards were made with three coating patterns (A = cross perpendicular, B= combine A and C, and C= paralell) and five zephyr layers using urea formaldehyde adhesive. They were pressed for 20 min at a pressure of 25 kgf/cm² and a temperature 120 ºC, to a target density of 0.80 g/cm³ and a size of 300 mm X 300 mm X 12 mm. Our results showed that the physical and mechanical properties fulfilled the standards of JIS A 5908-2003. The best physical properties were found in the type C layer pattern, which had a density of 0.82 g/cm³, Mouisture Content of 9.46%, Water Absorpsion of 16.49%, and Thickness Swelling of 16.49%. The best mechanical properties—Modulus Of Elasticity and Modulus Of Repture —were also found in the type C layer pattern, with values of 35.2 x 10-3 kgf/cm² and 603.9 kgf/cm², respectively. However, the best IB and screw holding strength (SW) results were found with the type B layer pattern (Internal bonding B of 38.65 kgf/cm², Screw Withdrawl of 145.11 kgf).
Performance Evaluation of an Optimized Floating Breakwater in Oblique Waves with a Higher-Order Boundary Element Method Mahmuddin, Faisal; Kashiwagi, Masashi
Makara Journal of Technology Vol. 18, No. 1
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Abstract

In the previous study, the optimal performance of a two-dimensional (2D) floating breakwater shape was obtained. The performance of this shape was also confirmed with a model experiment in a towing tank. Moreover, the shape’s performance in three dimensions (3D) was investigated in a subsequent study. However, to predict the shape’s performance in a real application more accurately, the shape’s characteristics in oblique waves must also be evaluated. In this study, the performance and characteristics of the model (hydrodynamic forces, body motions, wave elevations, and drift forces) are computed using a higher-order boundary element method (HOBEM). The HOBEM, which is based on the potential flow theory and uses quadratic representation for quadrilateral panels and velocity potentials, can be used to obtain more accurate results with fewer panels compared to the conventional panel method (CPM). The computational accuracy is confirmed by using Haskind-Newman and energy conservation relations. In this study, 3D wave effects were verified, and the body motions were much smaller compared to the 2D case. In addition, although the performance in terms of wave elevations depends on the measurement positions, the optimal performance obtained in the 2D case can be realized for a longer body length.
Digestibility of Betung Bamboo Fiber Following Fungal Pretreatment Fatriasari, Widya; Syafii, Wasrin; Wistara, Nyoman J.; Syamsu, Khaswar; Prasetya, Bambang
Makara Journal of Technology Vol. 18, No. 2
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Abstract

This research evaluated the effect of fungal pretreatment of betung bamboo fibers and enzymatic- and microwaveassisted hydrolysis on the reducing sugar yield. The enzymatic hydrolysis of the pretreated biomass was carried out with cellulase and 10 and 20 FPU/g of substrate in a shaking incubator at 50 °C and 150 rpm for 48 h. The sulfuric acid concentration used in the microwave-assisted acid hydrolysis was 1.0, 2.5, and 5%, either with or without the addition of activated carbon. Microwave irradiation (330 Watt) was applied for 5–12.5 min. The yield of reducing sugar was better with the microwave-assisted acid hydrolysis, and the yield tended to increase with an increase in the irradiation time. Based on the dry weight of the initial biomass (bamboo), pretreatment with 5% inoculum loading resulted in a higher reducing sugar yield (17.06%) than with 10% inoculum loading (14.54%). At a 1% acid concentration, the formation of brown compounds decreased, followed by a reduction in the reducing sugar yield. The addition of activated carbon at a 1% acid concentration seemed to be of no benefit with respect to the yield in the microwaveassisted acid hydrolysis. The pretreatment with the 5% inoculum loading for 12.5 min at 1% acid concentration resulted in the highest reducing sugar yield. Under these conditions, the yield was 6.3-fold that of the reducing sugar yield using 20 FPU/g of cellulase. The rate of bamboo hollocellulose hydrolysis reached 22.75% of the maximum theoretical reducing sugar reducing sugar of dry biomass.
Adjustable Resonance Frequency of RF-MEMS Capacitor by Using Comb- Drive Actuators: A Design Approaches Tamsir, Agus Santoso; Wijaya, Sandy Tannu; Majlis, Dato’ Burhanuddin Yeop
Makara Journal of Technology Vol. 18, No. 2
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Abstract

The needs of smaller size RF varactor is a must today, and MEMS comes to be the potential one. In this paper we proposed an adjustable resonance RF-MEMS varactor by using comb-drive actuators placing in each side of the square movable plate. In our preliminary simulation, we found that the device can work properly but some constraints comes such as the dominancies of harmonic resonance frequencies that influences into the nominal capacitances. Therefore for the next step of development we have to find out the window of the structural dimension for a certain spans and a certain operating frequencies.
Properties of Lignin from Oil Palm Empty Fruit Bunch and Its Application for Plywood Adhesive Risanto, Lucky; Hermiati, Euis; Sudiyani, Yanni
Makara Journal of Technology Vol. 18, No. 2
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Abstract

Lignin from lignocellulosic biomass is a potential biopolymer for wood adhesive. The aims of this study were to characterize lignin isolated from the black liquor of oil palm empty fruit bunch fiber pretreated with steam explosion in alkaline conditions and to examine the bond quality of aqueous polymer isocyanate (API) adhesive prepared from lignin, natural rubber latex (NRL), and polyvinyl alcohol (PVA) as base polymers with isocyanate crosslinkers. Lignin was precipitated from the black liquor by adding hydrochloric acid; then the precipitate was separated by filtration, thoroughly washed with water up to pH 2 and pH 5, and dried. The isolated lignin was characterized by ultimate analysis, UV spectroscopy, FT-IR spectroscopy, and thermal analysis. Three-layer plywood samples were prepared, and the bond strengths of the plywood samples were determined in dry conditions and after cyclic boiling. The lignin isolates with different pH values did not have significantly different chemical and thermal properties. Both lignin isolates had similar C, H, and O contents, identical functional groups in the FTIR spectra, similar absorption in the UV spectra, and high decomposition temperatures. The base polymers composition that could produce API adhesive for exterior applications was NRL/PVA/lignin (4/4/2). The use of more lignin in the adhesive formulation decreased the bond strength of the plywood.
Argon Ion Irradiation Effect on the Magnetic Properties of Fe-Al2O3 Nano Granular Film Purwanto, Setyo; Sakamoto, Isao
Makara Journal of Technology Vol. 18, No. 2
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Abstract

We studied the effect of Argon (Ar) ion irradiation on Fe-Al2O3 nanogranular thin film. X-ray diffraction (XRD) patterns show that the ion dose might promote the growth of the Fe2O3 phase from an amorphous phase to a crystalline phase. The magnetic and magnetoresistance properties were investigated using a vibrating sample magnetometer (VSM) and a four point probe (FPP). The results suggest that percolation concentration occurred at the 0.55 Fe volume fraction and with a maximum magnetoresistance (MR) ratio of 3%. The present MR ratio was lower than that of previous results, which might be related to the existence of the α-Fe2O3 phase promoted by Ar ion irradiation. CEMS spectra show ion irradiation induces changes from superparamagnetic characteristics to ferromagnetic ones, which indicates the spherical growth of Fe particles in the Al2O3 matrix.
Make or Buy Analysis Model Based on Tolerance Design to Minimize Manufacturing Cost and Quality Loss Rosyidi, Cucuk Nur; Akbar, Reza Rizkichani; Jauhari, Wakhid Ahmad
Makara Journal of Technology Vol. 18, No. 2
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Abstract

In a manufacturing company, manufacturing costs, or component prices, and tolerance will affect the price and the quality of a product. Companies must produce high-quality products with low manufacturing costs in order to keep their products competitive in the market; however, it is difficult to produce a high-quality product with a low manufacturing cost. Companies have difficulties in determining the components to be produced using their own manufacturing facilities (make) or outsourced to their suppliers (buy). Hence, a make or buy analysis is needed to minimize the manufacturing costs and quality loss and to determine the optimum alternative regarding make or buy decisions. This paper discusses an optimization model of a make or buy analysis for a manufacturing company in order to minimize the manufacturing costs and the quality loss in terms of manufacturer and customer quality loss. A numerical example is provided to show the application of the model using a simple assembly product consisting of three components. There are two machines that can be used to produce the components and three alternatives of suppliers to fulfill the order. Each machine and supplier have different characteristics in terms of manufacturing costs and its tolerance.

Page 26 of 49 | Total Record : 485

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