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EPI International Journal of Engineering
Published by Universitas Hasanuddin
ISSN : 26155109     EISSN : 26210541     DOI : https://doi.org/10.25042/epi-ije
Core Subject : Science, Engineering,
Civil Engineering, Building, Construction & Architecture Computer Science & IT Control & Systems Engineering Electrical & Electronics Engineering Engineering
EPI International Journal of Engineering (EPI-IJE) is published and managed by Center of Technology, Faculty of Engineering, University of Hasanuddin (CoT, FoE, UNHAS), Indonesia. The main objective of this international journal is to create publishing opportunities and to disseminate knowledge in engineering-related topics collected from all over the world. A wide range of topics may be accepted, including from both conventional engineering and newly developed fields. Multi-disciplinary and Inter-disciplinary fields are encouraged to submit, and the topic on engineering education is also welcome. Manuscripts should be in English only. This journal system is open free-access to public in electric form, and the paper-form journal is also available. No fee is charged to accepted papers. On acceptance of submitted paper, authors are asked to submit a short copy-right form, but the authors have rights to reuse their work. The submitted manuscripts are under peer review at least by two reviewers, and publication is made biannually.
Arjuna Subject : Teknik (semua kategori) - Teknik (Lain-Lain)
Articles 168 Documents
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Adaptive Vibration Control of Smart Structure Using Deep Reinforcement Learning Shinya Honda; Yuta Imura; Katsuhiko Sasaki; Ryo Takeda
EPI International Journal of Engineering Vol 5 No 2 (2022): Volume 5 Number 2, August 2022
Publisher : Center of Techonolgy (COT), Engineering Faculty, Hasanuddin University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25042/epi-ije.082022.03

Abstract

In this research, the authors developed an adaptive control method using deep reinforcement learning which is a kind of machine learning to suppress the vibration of smart structures. This method just requires information about the control response and input, and don’t require numerical models for the controlled object to design the controller. We experimented to verify the effectiveness of this method. In this experiment, a smart structure fabricated by an aluminum plate and a piezoelectric actuator was used as a controlled object. Three kinds of reinforcement learning algorithms are employed, Deep Q Network (DQN), Deep Deterministic Policy Gradient (DDPG), and Twin Delayed DDPG (TD3), and the control performance is compared. As a result, we succeeded in reducing the norm of the frequency response to impulse disturbance by up to about 40 dB compared to the uncontrolled case. This demonstrates the applicability of the control method using deep reinforcement learning to adaptive vibration control.
Development of Vibration Measurement System using a Microcontroller Koji Sekine; Keigo Hayakawa
EPI International Journal of Engineering Vol 5 No 2 (2022): Volume 5 Number 2, August 2022
Publisher : Center of Techonolgy (COT), Engineering Faculty, Hasanuddin University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25042/epi-ije.082022.04

Abstract

It is important to interpret resonance in the design to reduce the vibration of mechanical structures, and to verify this resonance phenomenon by experiments and theoretical approach. When the vibration of a continuous system is observed using a vibration system, the experience and skill of the observer affect the measurement accuracy of the natural frequency and vibration modes. Therefore, in this study, a vibration measurement system is developed to stably and quantitatively verify the natural vibration of the beams using a microcontroller and an ultrasonic sensor. The vibration measurement system consists of a microcontroller, a vibration motor and an ultrasonic sensor. The accuracy and validity of the natural frequencies of the beams measured by the system are discussed, and the performance of present system is evaluated on the basis of the measurement results of the natural frequencies and the natural vibration waveforms.
Vibration Analysis of Free Rectangular Plates Constrained by Translational Edge Springs Narita, Yoshihiro
EPI International Journal of Engineering Vol 6 No 1 (2023): Volume 6 Number 1, February 2023
Publisher : Center of Techonolgy (COT), Engineering Faculty, Hasanuddin University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25042/epi-ije.022023.02

Abstract

This paper aims to present comprehensive lists of accurate natural frequencies of isotropic thin free rectangular plates constrained only by translational springs distributed uniformly on the edges. Analytical and numerical approaches are employed to study the free vibration of the plates. The first approach is an extension of Ritz method, and second approach is the finite element method coded by the author. Numerical examples cover rectangular plates from totally free plate to totally simply supported on all edges. Convergence and comparison studies are made to establish accuracy of these solutions. Nine numerical examples are presented in terms of different of elastic constraints, and the lowest six frequency parameters are provided in the examples with different aspect ratios.
Energy-Saving Driving for a Flexible Manipulator by Utilizing Micro Fiber Composite Akira Abe
EPI International Journal of Engineering Vol 5 No 2 (2022): Volume 5 Number 2, August 2022
Publisher : Center of Techonolgy (COT), Engineering Faculty, Hasanuddin University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25042/epi-ije.082022.06

Abstract

In this paper, we examine a point-to-point motion task of a flexible manipulator with macro fiber composite (MFC) and then propose a new feedforward control method to suppress driving energy and residual vibration simultaneously. For this, we use an MFC attached to one side of the flexible manipulator that has one revolute joint as an actuator. We attempt to express the joint angle in the control technique by combining cycloidal and polynomial functions. On the other hand, the input voltage profile of the MFC is expressed using Gaussian functions. The trajectory of the joint angle and the input voltage profile are dependent upon the coefficients of the polynomial function and the Gaussian functions, respectively. The trajectory and the input voltage profile are optimized simultaneously to cancel the residual vibration under saving energy by tuning the coefficients using the particle swarm optimization algorithm. The effectiveness of the proposed method is verified by performing simulations and experiments. Thus, our findings confirmed that the simultaneous optimization of the trajectory of the joint angle and the input voltage of the MFC saves more energy than only the optimization of the trajectory. Therefore, we could establish an energy-saving feedforward control method by driving two actuators.
The Effect of Spot Welding Parameters for Dissimilar Material Mild Steel and Galvanizes Steel on Nugget Size and Mechanical Strength Azwar Azwar Hayat; La Ode Al Muslim; Ahmad Yusran Aminy
EPI International Journal of Engineering Vol 5 No 2 (2022): Volume 5 Number 2, August 2022
Publisher : Center of Techonolgy (COT), Engineering Faculty, Hasanuddin University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25042/epi-ije.082022.05

Abstract

The objective of this research was to analyze the effect of spot welding parameters on the size of the weld nugget and the maximum shear strength on dissimilar material mild steel and galvanized steel. The Taguchi and ANOVA methods were used to determine the welding parameters’ contribution to joint quality. Experimental design using Minitab-19 software with Taguchi method of 3 level 3 factor with L27 runs. Specimen size and dimensions were made using ASTM D1002 standard, with a plate thickness of 0.8 mm. Taguchi analysis S/N ratio data mean for weld nugget diameter with three levels of current used, 4 kA, 6 kA, and 8kA, shows the most influential on the diameter of the weld nugget was at 8 kA. The three levels of welding time used, 2s, 4s, and 6s, show the most influential on the diameter of the nugget the weld was at the third level for 6 seconds. It found that there was no significant difference in the size nugget at the three electrode pressure levels of 30 Ppsi, 40 Psi, and 50 Psi. Based on the tensile test and Taguchi analysis, the lowest shear strength was found in a weld nugget size of 3.15 mm at a welding current of 4 kA, a welding time of 2 seconds, an electrode pressure of 30 Psi, with a shear tensile strength of 300.19 N. Along with an increase in the size weld nugget correlated to an increase of shear strength. The highest shear tensile strength was found in the nugget size of 4.16 mm, with a welding current of 8 kA, welding time of 2 seconds, electrode pressure of 50 Psi, with a shear tensile strength of 3383.43 N. From the ANOVA, it found that the three factors of spot welding parameters were used, the most influential parameter in the formation of weld nuggets was welding current with a contribution of 84.86% then followed by welding time with a contribution of 14.86% and electrodes force with a contribution of 0.13%. Then from the three factors of spot welding parameters that were used the most influential parameter on the maximum shear tensile strength was the welding current with a contribution of 95.86 % then followed by welding time with a contribution of 0.52% and electrodes force with a contribution of 0.05%.
Development of A Presence System for Students Using QR Code Based on Android Application Mar'atuttahirah Mar'atuttahirah; Mardhiyyah Rafrin; Mahdaniar Mahdaniar; Putri Ayu Maharani
EPI International Journal of Engineering Vol 5 No 2 (2022): Volume 5 Number 2, August 2022
Publisher : Center of Techonolgy (COT), Engineering Faculty, Hasanuddin University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25042/epi-ije.082022.07

Abstract

The Department of Information System at Institut Teknologi B.J. Habibie still physically records each student's attendance by having them sign a presence sheet for each course. Due to the ease with which fraudulent signatures can be used to manipulate the traditional system, there may be some issues. Additionally, manual presence recapitulation takes more time and could be less precise and effective. This research aims to develop a prototype of Android-based application of student presence system with QR Code technology in the Department of Information System, Institut Teknologi B.J. Habibie. Following the creation of the presence system prototype, ISO 25010 quality standards were used to evaluate the application. The criteria evaluated are functionality, usability, portability, performance efficiency, and security. The application’s functionality was tested by two system experts by using Guttman Scale and it gained 100% yes answer. The usability was tasted from 30 users rating the application usability through a survey using Likert Scale, it achieved the average percentage of positive answers is 91%. The performance efficiency was classified as grade A by GTmetrix testing site. Similarly, the security system tested by sslabs.com achieved grade A. Furthermore, the portability was tested by using 4 different web browsers for the web version and by installing the application on 4 different smartphones and they showed no errors. Based on the overall assessment result, the Android-based Student Presence System is feasible, efficient, suitable and secure.
Study Experimental the Effect of Normalizing Treatment and Galvanic Pack Carburizing Process on Mechanical Properties of Low Carbon Steel Citra Wahyu Annisa; Ilyas Renreng; Lukamnul Hakim Arma; William Pian
EPI International Journal of Engineering Vol 5 No 2 (2022): Volume 5 Number 2, August 2022
Publisher : Center of Techonolgy (COT), Engineering Faculty, Hasanuddin University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25042/epi-ije.082022.09

Abstract

Steel is the type of metal most often used in engineering. This study aimed to improve the mechanical properties of mild steel in terms of hardness, ductility, and other mechanical properties and to compare the hardness of carburized steel by galvanic treatment with non-galvanic carburizing of the steel. This research was carried out by varying the heat treatment process, namely carburizing with galvanic heat treatment and carburizing without galvanic, where the carburizing process uses activated carbon coconut shell charcoal with a weight percentage of 80% and 20% of K2CO3 (Potassium Carbonate) at a temperature of 9000C with a holding time of 60 minutes, 120 minutes and 180 minutes. The results obtained from this study indicate that the mechanical properties (hardness) of carbon steel increase at a temperature of 9000C with a holding time of 1 hour on the galvanic heating method with a better hardness value than the hardness of steel on the non-galvanic method. The hardness value obtained in the galvanic method is 94.06 HRB, while in the non-galvanic method, it is 76.4 HRB. And the pearlite phase is formed, increasing the hardness value on the surface of the specimen.
Effect of Mg and Zn Composition Variations on Surface Characteristics and Flexural Strength of Biodegradable Mg-Zn-Ca Alloys by Powder Metallurgy Method Yuliana Simons; Onny S. Sutresman; Hairul Arsyad
EPI International Journal of Engineering Vol 5 No 2 (2022): Volume 5 Number 2, August 2022
Publisher : Center of Techonolgy (COT), Engineering Faculty, Hasanuddin University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25042/epi-ije.082022.08

Abstract

This study aims to determine the Mg-Zn-Ca alloy's surface characteristics and flexural strength using powder metallurgy methods. The Mg-Zn-Ca alloy was prepared by powder metallurgy method with three composition variations (89Mg-10Zn-1Ca, 93Mg-6Zn-1Ca and 97Mg-2Zn-1Ca). The Mg-Zn-Ca powder alloy was mixed with the dry milling process for 60 minutes. After mixing, the compaction process is carried out with a load of 200 MPa. Then, the sintering process was carried out at a temperature of 500 ℃ and held for 3 hours with a furnace fed with argon gas. The sintering results were characterized by the microstructure of the Mg-Zn-Ca alloy using SEM and XRD. After that, it was carried out to test the flexural strength of the Mg-Zn-Ca alloy. SEM results obtained that the 89Mg-10Zn-1Ca alloy sample has less porosity and a smaller pore diameter compared to the 93Mg-6Zn-1Ca alloy sample and the 97Mg-2Zn-1Ca alloy sample, which has more porosity and has a smaller diameter. Bigger pore. The results from XRD had the highest peak in the 89Mg-10Zn-1Ca alloy sample, seen from a crystalline spectrum of 82.4%. The results of the bending test, the most optimal flexural strength occurred in the 89Mg-10Zn-1Ca alloy sample, which was 0.579 Mpa. The results from XRD had the highest peak that occurred in the 89Mg-10Zn-1Ca alloy sample, seen from a crystalline spectrum of 82.4%. The results of the bending test, the most optimal flexural strength occurred in the 89Mg-10Zn-1Ca alloy sample, which was 0.579 Mpa. The results from XRD had the highest peak in the 89Mg-10Zn-1Ca alloy sample, seen from a crystalline spectrum of 82.4%. The results of the bending test, the most optimal flexural strength occurred in the 89Mg-10Zn-1Ca alloy sample, which was 0.579 Mpa
A Study of the Effect of Additional Magnesium (Mg) on Erosion-Corrosion Resistance and Bending Strength in Aluminum A383 Alloy Amiruddin, Arya Ahmad; Arma, Lukmanul Hakim; Arsyad, Hairul
EPI International Journal of Engineering Vol 6 No 1 (2023): Volume 6 Number 1, February 2023
Publisher : Center of Techonolgy (COT), Engineering Faculty, Hasanuddin University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25042/epi-ije.022023.01

Abstract

In this study, evaluating the erosion-corrosion resistance and mechanical properties, especially the bending strength of aluminum alloy A383 with the addition of 4%, 6%, and 9% magnesium was investigated with variations in velocity (45l/h, 60l/h, and 75l/h). and angle variations (30º, 40º, and 50º) using 12% sodium hypochlorite solution. The test equipment used is an injection diaphragm pump in the recirculation system for 4 hours per sample. The results showed that the erosion-corrosion resistance of A383 alloy is proportional with the increase of magnesium addition to the alloy maximum weight loss occurs at an impact angle of 30° with a velocity of 75 l/h. The degradation decreased slightly with increasing the impact angle and decreasing velocity. Analysis of the erosion-corrosion mechanism shows that the corrosion process dominates material damage rather than erosion. The results of the bending test showed that the highest strength was A383 9% Mg which was 366.09 MPa, and the lowest bending strength was A383 material without magnesium addition which was 261.80 MPa. From these results, it can be concluded that the addition of magnesium (Mg) to aluminum alloy A383 contributes to increased corrosion resistance and increased bending strength.
Analysis of Thermal Comfort of Office Buildings (Case Study: Hasanuddin University Rectorate Building) Kamaruddin, Nurhayati Hayati; Hamzah, Baharuddin; Jamala, Nurul
EPI International Journal of Engineering Vol 7 No 1 (2024): Volume 7 Number 1, February 2024
Publisher : Center of Techonolgy (COT), Engineering Faculty, Hasanuddin University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25042/epi-ije.022024.06

Abstract

Thermal comfort is one of the fundamental aspects of indoor environmental quality and it is closely related to occupant satisfaction and energy use in buildings. The purpose of this research was to analyze the thermal conditions of the student affairs rooms (Interest & Talent Room and Student Meeting room) at second floor and the academic and education rooms (Academic Meeting room, Academic Registration room, and Head of Education and Evaluation room) at seventh floor of Hasanuddin University rectorate building. This study used a quantitative method using a survey where the researcher asked several respondents about the level of thermal comfort of the room occupants when the volume of air conditioner (AC) is increased gradually every day at 18o C, 22o C, and 27o C. In addition, measurements were conducted using HOBO from 08.00 – 17.00 to obtain data in the form of air temperature, humidity, and air velocity in the room. At the same time, respondents were asked to fill out a questionnaire asking the level of comfort felt by the room occupants at that time. The results showed that the average air temperature at 18o C is 24.62o C, humidity is 63.108% and air velocity is 0.144 m/s. At a temperature of 22o C, the average air temperature is 24.78o C, humidity is 60.684%, and the air velocity is 0.142 m/s. At a temperature of 27o C, the average air temperature is 25.97o C, humidity is 64.022%, and the air velocity is 0.127 m/s. The results showed that the respondents felt ‚cold‘ when the volume was at 18o C, they felt 'comfortable' when the volume was at 22o C, and they felt ‚neutral‘ when the volume was at 27o C. In the end, temperatures of 22o C and 27o C can be used as a reference in the use of air conditioning temperatures in the room.

Page 14 of 17 | Total Record : 168

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