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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. 18, No. 1" : 7 Documents clear
Synthesis and Characterization of Soy-Based Polyurethane Foam with Utilization of Ethylene Glycol in Polyol Firdaus, Flora Elvistia
Makara Journal of Technology Vol. 18, No. 1
Publisher : UI Scholars Hub

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Abstract

The use of vegetable oils on replacing petroleum has attracted attention of many researchers. The chemical structure of vegetable oils are different from petrochemicals, so the structure of soybean oil has to be chemically modified through its unsaturated fatty acid chain in triglyceride. A two step process was conducted for the preparation of soy-polyol in designated temperatures; 50 °C, 60 °C, and 70 °C. Ethylene glycol (EG) as co-reagent was taking part in soy-polyol synthesis, and the soy-polyol was used as a sole polyol for polyurethane synthesis. Referred to the previous study, the existence of EG in polyurethane synthesis can improved physical properties of polyurethane foam. The aim of this research is using soy-derived polyol for petro-polyol replacement aligned with drop-off of petro-derived reagent; EG. One step process was applied for the foam synthesis. The ingredients for foam synthesis; soy-polyol, Toluene diisocyanate (TDI): a mixture of 2.4 and 2.6 isomers in ratio of 80:20 (TDI T-80), surfactant, and distilled water. The synergize of stoichiometry ratio of co-reagent EG to soy-epoxide with best temperature, with the absence of EG in polyurethane formula can produce an ultimate property of polyurethane foam.
Dynamic Characteristic Identification of Seismic-Excited Multi-Story Buildings through Response-Only Technique Budipriyanto, Agung; Suprobo, Priyo
Makara Journal of Technology Vol. 18, No. 1
Publisher : UI Scholars Hub

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Identifying dynamic characteristics of civil engineering structures is still a challenging task. It intends to assess behavior of the structures under time-dependent loads. This paper discusses a methodology suitable for identifying the characteristics of multi-story buildings using only their measured response under earthquake ground excitations. Appropriateness of technique used for structural identification was corroborated through coherence of the structure’s responses. The methodology was applied for identifying the characteristics of 14-story and 20-story office buildings located in a high seismic region. Responses of these two buildings recorded during three different seismic ground motions were investigated. The buildings’ response spectral densities and singular values were computed and utilized to identify their dynamic characteristics, viz. modal frequencies, damping factors, and mode types such as bending or torsion mode. Results of this study were validated through comparisons with the results reported using different structural identification techniques. It indicated that the methodology implemented in this study was capable of identifying the dynamic characteristics of multi-story buildings using responses under seismic ground motions.
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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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
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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
Publisher : UI Scholars Hub

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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.

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