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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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The Relaying Network in Free-Space Optical Communications using Optical Amplifiers in Cascaded Configuration Darusalam, Ucuk; Raj, Arockia Bazil; Zulkifli, Fitri Yuli; Priambodo, Purnomo Sidi; Rahardjo, Eko Tjipto
Makara Journal of Technology Vol. 27, No. 2
Publisher : UI Scholars Hub

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Abstract

Optical relaying is the best technique to implement free-space optical (FSO) communications as a terrestrial platform. However, atmospheric turbulence (AT) limits the optical-propagation path length. In this study, the implementation of some optical amplifiers (OAs) in cascaded configuration, namely, erbium-doped fiber amplifiers, semiconductor OAs, and Raman amplifiers (RAs), are investigated through simulation. This study aims to search for the maximum link distance of an optical propagation and enhance the FSO performance caused by each configuration of OAs. The optical relaying network consists of three nodes, with each node designed with a space of several kilometers under the influence of AT. At the end of the destination, before the receiver, an optical band-pass filter is applied to perform noise filtering. Among the OAs in the cascaded configuration, the RA can expand the link distance of the optical-propagation path length to a range of 14.7–15.9 Km under the influence of a strong AT. The signal-to-noise ratio and bit error rate of the system are in the ranges of 24.1– 19.08 dB and 7.9 × 10−15–7.4 × 10−6, respectively.
Design and Prototyping of a Low-Cost High Frequency Antenna for Vicinity Coupling Devices Kommey, Benjamin; Addo, Ernest Ofosu; Tamakloe, Elvis
Makara Journal of Technology Vol. 26, No. 3
Publisher : UI Scholars Hub

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Abstract

This paper describes the development of a high frequency (HF) antenna for high output power vicinity coupling devices (VCDs) operating at 13.56 MHz. Key design parameters, such as RF power level, antenna size, and communication protocol, and their link to the antenna features and requirements, have been discussed. For efficient reader interrogation, detection, and recovery of transponder responses, a tuning circuit necessary to adjust the antenna power matching and resonance characteristics was designed and prototyped. The antenna was fed to an industry standard reader and evaluated for read range performance with vicinity cards. The designed antenna on the reader achieved a good read range, which demonstrated fair agreement with the calculated theoretical results.
Investigation of the Characteristic Thermal Retention Behaviour of Sandwich Glass-Fibre-Reinforced Composite Panels in Electric Oven Designs Agbo, Cornelius Ogbodo Anayo
Makara Journal of Technology Vol. 26, No. 3
Publisher : UI Scholars Hub

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Abstract

The focus of this paper is to experimentally investigate the characteristic heating and cooling behaviours of a sandwich glass fibre reinforced composite panel electric ovens. A portable conventional electric oven with two stack trays for product placement was designed and fabricated for the evaluation. The oven box consists of sidewalls and a ceiling made of glass-reinforced plastic (GRP) with sandwich glass wool insulation. The oven floor has, in addition to the sandwich panel, a ceramic tile plate placed on the chamber floor to separate the electric heating element. The oven characteristic thermal behaviour was obtained as different product load conditions were being simulated. The heat retention ability of the oven is quite impressive making it possible for the water simulated product to remain warm for up to 13 hours with the testing stockpot open and more than 27 hours with the pot covered. Energy is therefore conserved as the oven can be switched off while the product continues to process. The oven cooking efficiency of approximately 39% was obtained under standard stockpot water test. The oven is therefore suitable for both culinary activities and laboratory experiments requiring moderate temperatures.
User Classification Based On Mouse Dynamic Authentication Using K-Nearest Neighbor Chandranegara, Didih Rizki; Ashari, Anzilludin; Sari, Zamah; Wibowo, Hardianto; Suharso, Wildan
Makara Journal of Technology Vol. 27, No. 1
Publisher : UI Scholars Hub

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Abstract

Mouse dynamics authentication is a method for identifying a person by analyzing the unique pattern or rhythm of their mouse movement. Owing to its distinctive properties, such mouse movements can be used as the basis for security. The development of technology is followed by the urge to keep private data safe from hackers. Therefore, increasing the accuracy of user classification and reducing the false acceptance rate (FAR) are necessary to improve data security. In this study, we propose to combine the K-nearest neighbor method and simple random sampling and obtain a sample from a dataset to improve the classification of users and attackers. The results show that our proposed method has high accuracy for implement to practical system and reports the best results than previous research with a FAR of 0.037. Therefore, this method can be implemented in a real login system. The high false rejection rate of our proposed method will not be a problem because the most important thing in the login system is denying the attacker system access.
Experimental and Numerical Studies on the Compressive Strength Test of Recycled Aggregate Concrete using Digital Image Correlation Sentosa, Bastian Okto Bangkit; Ferdinand, Joshua; Handika, Nuraziz
Makara Journal of Technology Vol. 28, No. 1
Publisher : UI Scholars Hub

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Abstract

The utilization of recycled aggregate (RA) as substitute of natural aggregate in concrete contributes to the research of sustainable building construction materials. Many applications of RA have been studied worldwide. However, the application of RA with a specific range of strength and specific damage behavior requires further study. This research aims to examine the mechanical characteristics of RA concrete, particularly its load–displacement response and crack pattern, through the experimental and numerical studies of compressive strength test. Laboratory concrete waste from cylindrical sample with 30–35 MPa strength was chosen as RA. The digital image correlation (DIC) method was applied throughout the compressive tests. In the post-processing step of the DIC method, vertical and horizontal displacement and the strains of the observed concrete surface were predicted to detect the crack patterns at the initial and maximum load stages. Numerical modeling was then performed on the same shape by applying the concrete damage model by Mazars. Numerical modeling gives close results to the experimental ones from the initial stage to the maximum load stage. These results can be useful for further studies to improve the accuracy of numerical models for alternative building material, specifically for large structures.
Restorative Hand Therapy Exercise using IoT-Based Flex Force Smart Glove Chang, Yi Neng; Ishak, Mohamad Khairi; Ammar, Khalid
Makara Journal of Technology Vol. 27, No. 1
Publisher : UI Scholars Hub

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Abstract

Stroke has long been a major health concern in Malaysia, with cerebrovascular disease accounting for one-third of all deaths. Patients who have had a stroke have varying degrees of movement impairment, which can be improved with physiotherapy. A smart glove system is proposed in this paper to measure and visualize patient finger flexes in real-time remotely and record these flexes for further analysis to monitor and assess patient physiotherapy sessions. The system is designed to help physiotherapists evaluate physiotherapy exercises of patients and provide detailed information regarding the rehabilitation process. This paper also includes performance analysis and data from physiotherapy sessions using the system. Overall, the flex force smart glove shows promise in aiding restorative hand therapy exercises.
Effect of Lime Content, Curing Temperature, and Aging Condition on Low-Alkaline Concrete Pour, Mahdi Parsa; Sharghi, Reza Shaban; Nejati, Faezeh; Najafi, Elmira Khaksar
Makara Journal of Technology Vol. 27, No. 3
Publisher : UI Scholars Hub

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Abstract

This study determines how curing temperatures, aging condition, and hydrated lime contents affect the unconfined compressive strength (UCS), modulus of elasticity, and workability of low-alkaline concrete. Samples were prepared in two different groups to determine the optimum hydrated lime content and aging conditions to assess the mutual effect of NaOH molarity and curing temperature, that is, 70 °C for 48 h or room temperature, on samples with and without lime. The results showed that the increase in hydrated lime content affected alkali concentration. The samples with lime exhibited a clear peak in UCS (6 M NaOH) compared with the continuous increase for the samples without lime. Lime content had a positive effect on eliminating heat curing and prolonging aging time to enhance the Young’s modulus and compressive strength. This result is promising for in-situ concreting. Similar to the effect of alkali concentration, lime contributed to the loss in slump value. The scanning electron microscopy images showed the formation of N-(C)-A-S-H gels as the main reaction products. Moreover, internal cracking contributed to the lower UCS of samples with 9 M NaOH compared with those with 6 M NaOH.
Performance of a Solar Seawater Distillation with a Triangle Prism Cover and a Fin-Type Absorber Rachmanita, Risse Entikaria; Umam, Miftah Khoirul
Makara Journal of Technology Vol. 27, No. 1
Publisher : UI Scholars Hub

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Abstract

Solar-powered distillation is a seawater distillation method that utilizes solar heat as its main energy source for the purpose producing freshwater and a by-product of the distillation process in the form of salt. This study aims to determine the performance of a solar seawater distillation design with a semi-batch system by combining a fin-type absorber plate and a triangular prism cover. This design is equipped with a reflector and absorber plate, which has a surface area of 0.3969 m2 with a volume capacity of seawater that can be accommodated in a basin of ±24 liters. It uses a knockdown system on its components for convenience in the process of maintenance and repair. The test results show that the highest freshwater product produced is 0.245 liters and the quality of distilled water meets the standards for consumption. The highest efficiency of solar seawater distillation test results was 8.032% on the third day of testing with an average solar radiation intensity of 805.076 W/m2 . The efficiency of solar distillation of seawater is strongly influenced by the intensity of solar radiation received by the distillation apparatus.
Experimental Analysis Study Wave Drift Force of Moored Floating Production Units (FPU) Rifliansah, Arifin; Nugroho, Wibowo Harso
Makara Journal of Technology Vol. 28, No. 1
Publisher : UI Scholars Hub

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Abstract

Drift forces caused by sea waves and currents are an important aspect that needs to be studied in planning moored floating structures, especially Floating Production Units (FPU) type ships which are operated for oil and gas exploration. This study describes the drift forces on the FPU which is subjected to environmental loads in the form of waves. The slow-drift movement that occurs in a moored FPU, and experiencing irregular waves is a very important problem. The complexity of determining drift forces analytically and numerically requires the use of hydrodynamics model test. In the model test on a certain model scale the ship is equipped with several measuring instruments for measuring ship movement and the forces acting on the mooring lines. The Model testing was also carried out by providing a simulation of environmental forces in the form of currents and ocean waves which were varied in several wave headings. The magnitude of the mean wave drift force that occurs on FPU is very dependent on the heading angle of the wave excitation and current as well as the significant wave height and peak frequency.
Isolation and Characterization of Caffeine-Degrading Bacteria from Coffee Plantation Areas in Malaysia Dullah, Elvina Clarie; Farida Asras, Mohd Fazli
Makara Journal of Technology Vol. 27, No. 3
Publisher : UI Scholars Hub

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Abstract

Decaffeination by microbial degradation is currently the most optimal and low-cost approach, involving only microbial cells and/or their enzymes. The bacterium was characterized using a series of biochemical tests. Positive results were obtained from carbohydrate fermentation, citrate utilization, and catalase tests, while negative results were obtained from Voges-Proskauer (VP) and indole tests. Three different caffeine concentrations of 0.25%, 0.4%, and 2% were tested and measured through Gas Chromatography-Mass Spectrophotometry (GC-MS) analysis. The highest caffeine reduction (89.25%) was found when 0.25% caffeine was used in the media. Only a small amount of caffeine was reduced to 0.4% and 2%, with 34.78% and 46.16%, respectively. Under microscopic observation, the shape of the isolated bacteria was rod bacilli and was stained with a pink color, which indicates Gram-negative bacteria. Comparing the results with previous research and observing the color of the pure culture, which revealed a yellow color, bacteria isolated from the coffee plantation area can be concluded to be a partially identified Pseudomonas sp.

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