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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 5 Documents
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Search results for , issue "Vol. 28, No. 1" : 5 Documents clear
Secured Blockchain and Fractional Discrete Cosine Transform-based Framework for Medical Images Yadav, Abhay Kumar; Vishwakarma, Virendra P.
Makara Journal of Technology Vol. 28, No. 1
Publisher : UI Scholars Hub

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Abstract

Images can store large amounts of data and are useful for transmitting large amounts of information across different geographical locations using different cloud services. This data sharing increases the chances of cyber-attacks on digital images. Blockchain has properties that enable it to work as a solution to this problem, providing enhanced security and unchangeable storage. However, image size poses a challenge in image storage, as it increases the related storage cost. Compressing images using fractional discrete cosine transform (fctDCT) reduces the amount of data required to express an image securely. This paper presents a novel framework for securely storing and retrieving medical images by extracting feature maps from medical images using fctDCT, followed by encoding and storing a feature map on a decentralized cloud and linking it on a blockchain. The integration has been implemented using α angles, which are stored on the blockchain and need to be identical at the storage and retrieval stage, as only the authentic user would have access to unique α angles and the number of coefficients that have been used in storing their medical images. The proposed novel approach offers numerous benefits, including improved data sharing and collaboration, enhanced security, compression, and efficient retrieval and processing of medical image data. The performance of the proposed framework was evaluated in terms of image quality metrics such as mean square error, peak signal-to-noise ratio, structural similarity index measure (SSIM), and multi SSIM by employing it with correct and incorrect α values.
Thermal Performance Investigation of Thermoelectric Cooling System with Various Hot-Side Cooling Methods Prasetyo, Bowo Y; Rosulindo, Parisya P; Wang, Fujen
Makara Journal of Technology Vol. 28, No. 1
Publisher : UI Scholars Hub

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Abstract

Thermoelectric devices have been widely used in various applications, including cooling and power generation. The potential application of thermoelectric cooling systems has been studied. However, these systems still face challenges in achieving optimal performance compared with other cooling systems. Several factors, including the hot-side cooling method, influence the performance of thermoelectric systems. This study aimed to investigate the effects of different hot-side cooling methods on the thermoelectric performance and thermal behavior of thermoelectric cooling systems. The testing methods involved the combination of the thermoelectric module with five hot-side heat exchangers, including a square heatsink, a round heatsink, a two-pipe heat pipe, four-pipe heat pipe, and a liquid cooler, with variations in the operating voltage. The experimental results reveal that the different heat exchangers considerably affected the system performance. The liquid cooler consistently achieved the lowest hot- and cold-side temperatures among all heat exchangers. In the case of the ratio of the cooling capacity and temperature difference across the module, the liquid cooler attained the highest values at 12 and 9 V. In addition, the square heatsink exhibited the highest ratio at 6 V. Meanwhile, the coefficient of performance (COP) values were relatively similar in the various heat exchangers, with the liquid cooler generally showing higher COP values.
Hybrid Method Neighbor Node Discovery in Wireless Sensor Networks: A Framework Mekala, Sagar; Kaila, Shahu Chatrapati; Matang, Jyothi Rani
Makara Journal of Technology Vol. 28, No. 1
Publisher : UI Scholars Hub

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Abstract

Wireless devices are now being adapted for diverse purposes, such as healthcare, agriculture, transportation, and tactical operations, which present challenges in network formation owing to high device mobility. Current methods rely on discovery techniques for forming wireless sensor networks (WSNs); however, the existing research has been criticized for its high time complexity and redundant neighbor discovery process. In this study, we provide a hybrid strategy to effectively handle the difficulties of locating neighboring nodes in WSNs. Our method combines several strategies to produce precise and effective neighbor detection. Herein, shared memory–based discovery, a beacon technique, and range and distance overlap detection comprise three main phases of the hybrid approach. This approach improves time complexity by ~50% and reduces redundant node discovery by nearly 30%.
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.
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.

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