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Jurnal Teknik Elektro
Published by Universitas Negeri Semarang
ISSN : 14110059     EISSN : 25491571     DOI : http://dx.doi.org/10.15294/jte
Core Subject : Engineering,
Electrical & Electronics Engineering
Arjuna Subject : -
Articles 482 Documents
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Coil-based Wireless Power Transfer for Implanted Pacemakers: A Brief Review Urfa Khairatun Hisan; Liya Yusrina Sabila; Muhammad Miftahul Amri
Jurnal Teknik Elektro Vol 15, No 1 (2023): Jurnal Teknik Elektro
Publisher : Jurusan Teknik Elektro, Fakultas Teknik, Universitas Negeri Semarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15294/jte.v15i1.42662

Abstract

Nowadays, implanted permanent pacemakers (PPM) users need to undergo periodic pacemaker replacement surgery. The surgery is needed since the pacemaker's battery is usually depleted in 5-10 years. This surgery, although poses relatively low health risks, is inconvenient for PPM users. Moreover, the surgery can still be dangerous for PPM users, especially considering that most of the users are elderly. PPM replacement surgery is also costly. In addition to the costs of the surgery itself, the PPM users need to bear the price of the new PPM every time they undergo surgery. Currently, when the PPM's battery runs out, the whole PPM needs to be replaced. This is conducted to prevent the possibility of a leak in the battery seal, which might allow the body fluids to enter the PPM. Typically, once a battery is inserted into the PPM, it will be permanently sealed along with all other electronic components, and thus, battery-only replacement is impossible. Thanks to the recent advancement of wireless power transfer (WPT) technology, a PPM replacement surgery might no longer be necessary in the near future. This article presents a brief review of the current state of coil-based WPT technology and its potential applications in pacemakers. Depending on the load and transmission distance, a recent WPT system for PPM could achieve WPT efficiency as high as 97.91% on air and 78% on pig tissue medium. In terms of output power, recent works that we have summarized showed that they are able to transmit power up to 5W on a WPT system implemented on a human phantom. We also discuss the challenges, limitations, and future prospects for WPT in the medical field, particularly for PPM applications.
Echocardiogram Image Quality Enhancement using Upsampling and Histogram Matching Methods Permana, Zendi Zakaria Raga; Puspasari, Ira
Jurnal Teknik Elektro Vol 14, No 2 (2022): Jurnal Teknik Elektro
Publisher : Jurusan Teknik Elektro, Fakultas Teknik, Universitas Negeri Semarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15294/jte.v14i2.42081

Abstract

The prevalence of heart disease has been increasing in the last ten years. One of the cardiac diagnostic tools is echocardiography. Echocardiogram medical images provide essential information, including shape, size, pumping capacity, heart function abnormalities, and location of heart damage, but echocardiogram images have high noise content and poor contrast, as well as limitations due to differences in anatomy or body mass. This will affect the reading results of patient diagnosis. Therefore, image quality improvement is needed by removing noise and increasing image contrast. This research has improved image quality using a method with low mathematical complexity and a fast computational process. The method used is the Upsampling method to generate a reference image. The quality of the image produced was the Nearest Neighbor upsampling method: 2.8 dB, Bi-linear Interpolation: 2.78 dB, and Bi-cubic Interpolation: 2.73 dB. Furthermore, the image with the highest SNR value is processed with Histogram Matching to accelerate improving image quality. The Histogram Matching image increases quality by more than 50% with a SSIM value of 0.54. The required computational process to apply this method to each medical image has an average duration of 0.4 s. This result provides a higher value than several methods using linear scaling and speckle reducing.
Design and Optimization of Discone Antenna for Medical Device Electromagnetic Interference Measurement Haryo Dwi Prananto; Dwi Mandaris; Aditia Nur Bakti; Achmad Munir
Jurnal Teknik Elektro Vol 15, No 1 (2023): Jurnal Teknik Elektro
Publisher : Jurusan Teknik Elektro, Fakultas Teknik, Universitas Negeri Semarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15294/jte.v15i1.39688

Abstract

The wide spread of the Internet of Things creates the possibility of electromagnetic interference in medical devices. Therefore, it is necessary to perform risk mitigation by finding the value of electromagnetic interference through measurements using wideband and omnidirectional antennas, e.g., the discone antenna. In this research, the optimization of the S11 value of a designed discone antenna was obtained using simulation from the effect of dimensional variations in discone parameters like disc diameter, cone bottom diameter, gap, and cone height on S11 characteristics. The parameters were combined for optimization. The design was fabricated, and the S11, radiation pattern, gain value and antenna factor, and the ability to measure interference through modeling were measured. Gain value and antenna factor were obtained using the gain-comparison method, which compared the antenna of interest against another antenna with a standard gain. The optimization was successfully performed with a better S11 value. At 5.2 GHz, the value of S11 was below -10 dB. The realization of the design showed similar results to the simulation, and it was found to be able to operate in the medical device frequency range (wideband). The ability of the discone antenna improved in terms of S11 value, especially at 5.2 GHz, where the value was below -17.443 dB. The radiation pattern of the designed antenna is omnidirectional. Additionally, validation was carried out by providing gain value and antenna factor. It has been proved that the designed discone antenna could measure interference successfully by modeling interference sources as electric field sources from all directions.
Ancillary Services of a Grid-Connected Inverter with Overcurrent Protection Capability under Voltage Sag Sepannur Bandri; Zuriman Anthony; Rafika Andari; Fauzan Ismail
Jurnal Teknik Elektro Vol 15, No 1 (2023): Jurnal Teknik Elektro
Publisher : Jurusan Teknik Elektro, Fakultas Teknik, Universitas Negeri Semarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15294/jte.v15i1.43870

Abstract

The Distributed Generator of a Photovoltaic System (DGPVS) is an essential factor for future power plant generation, and it can be created by connecting multiple small power plant generators in a microgrid system. This paper focuses on the overcurrent protection of a three-phase grid-connected inverter (3P-GCI) under voltage sag conditions in sustaining connection loss between the 3P-GCI and the primary grid, which involves voltage instability. The ancillary service shows more advantage in overcurrent protection during voltage sags, which limits the generated current under sag duration. Its service can protect the inverter and avoid more disturbances to the primary grid because the 3P-GCI remains connected. Proposed LVRT strategy with limit current feature play the role to protect 3P-GCI under voltage sag. In the normal grid, the 3P-GCI can inject 302W of active power with a power factor (PF) equal to one. 1.4% of VTHD and 4.3% of ITHD shows the performance of the proposed system. Meanwhile, the 3P-GCI injects 239VAr reactive power and reduces injected active power to 135W which is essential to remain connected to the primary grid during voltage sags and limit the generated current. The validation results show that this prototype successfully compensates for the grid voltage drops by injecting 239Var of reactive power and limiting its generated current to 1.592A.
Underwater Acoustic Intensity Analysis using Noise Assisted-MEMD with Varying Distances Laily Fajarwati; Yusron Feriadi; Endang Widjiati
Jurnal Teknik Elektro Vol 15, No 1 (2023): Jurnal Teknik Elektro
Publisher : Jurusan Teknik Elektro, Fakultas Teknik, Universitas Negeri Semarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15294/jte.v15i1.43878

Abstract

With current developments, underwater communication using acoustic signals is widely used. Many things need to be prepared to support a reliable underwater communication system, such as taking measurements in a test tank to find out the correct measurement configuration. Underwater acoustic intensity measurements, which are detailed in this paper, are performed in the test tank using distance variation schemes. Measurements were made at various distances of 4, 10, 20, and 50 meters from the signal source. The hydrophone that was used has a sensitivity of -180 dB re 1V/µPa. The hydrophone was placed at a depth of 2 meters below the surface of the water in the test tank, which divided the test tank depth in half to ensure that reflections from the bottom and the surface were kept to a minimum. However, the problem is that there are noisy signals at different frequencies. This paper proposes a method using Noise Assisted - Multivariate Empirical Mode Decomposition (NA-MEMD) to decompose the signal and then calculate the sound intensity. The result shows that an increase in the distance between the transmitter and receiver, also causes a change in the intensity with an average change of 0.467 dB/meter. It is concluded that the NA-MEMD approach was shown to be successful in decomposing the intended signal from the noise to equalize the quality of the signal received at different distances, and the correlation between intensity value and change in distance is resilient, with a correlation value of 0.98, indicating a very strong correlation.
Controlling the Output Voltage of a Step Up-Down Five-Level Inverter Leonardus Heru Pratomo; Slamet Riyadi; Agengkarunia Cahyadi Wibawa
Jurnal Teknik Elektro Vol 15, No 1 (2023): Jurnal Teknik Elektro
Publisher : Jurusan Teknik Elektro, Fakultas Teknik, Universitas Negeri Semarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15294/jte.v15i1.43877

Abstract

The increasing demand for electrical energy must be balanced with using renewable energy. However, the use of renewable energy requires a system to maximize the conversion of renewable energy into electrical energy. Various topologies have been studied to achieve maximum energy conversion. Two types of inverters, namely step up-down, have been widely used but have their respective limitations. Step-down inverters can only be used in lower output voltage than input voltage conditions with simple control, while step-up inverters can only operate in higher output voltage than input voltage conditions. This paper aims to combine these two converters to have both step-up-down voltage functions, with the goal of expanding the operating range and maintaining the advantages of each type. Thus, a topology called a step-up-down five-level inverter with a simple voltage-controlled capacitor balancing system is proposed in this paper. Finally, the simulation and laboratory tests were done. This inverter operates in step-up-down voltage, and the voltage in capacitors is always balanced to reach the desired level. The voltage control was done to get the constant voltage event the load was changed.
Optimizing Investment: Combining Deep Learning for Price Prediction and Moving Average for Return-Risk Analysis Hastomo, Widi; Karno, Adhitio Satyo Bayangkari; Masriyanda, Masriyanda; Sestri, Ellya; Kardian, Aqwam Rosadi; Azis, Nur; Dewanto, Ignatius Joko; Rasyiddin, Ahmad; Sundoro, Aries; Kamilia, Nada
Jurnal Teknik Elektro Vol 14, No 2 (2022): Jurnal Teknik Elektro
Publisher : Jurusan Teknik Elektro, Fakultas Teknik, Universitas Negeri Semarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15294/jte.v14i2.45002

Abstract

The ability to analyze predictions marks something going up or down, as well as the level of possible risk taken into account by much-needed stock investors. In a study, this analysis of risk and correlation between shares was calculated using the method of moving averages (MA). Besides that, a dataset of 4 stocks (Apple, Google, Microsoft, and Amazon) also performed prediction mark stock in period time next (future) with the use of the neural network method (deep learning) Long Short-Term Memory (LSTM) model. The result of programming in the Python language is several visualizations for easy graph-reading information. This article presents new research that aims to fill the gap in understanding investment analysis for beginners by visualizing risk and return analysis on shares. The results reveal that changes in stock sales volume did not occur significantly, although the short and long-term MA charts for the four stocks tended to fluctuate, offering new insights into investment analysis and providing a basis for future development. The best accuracy results were on MSFT shares, with an achievement of 0.9532 and a loss value of 0.0014. Thus, MSFT shares can be used as a priority for investment. Therefore, this research adds a new dimension to the literature and paves the way for further investigations in risk and return analysis and stock prediction using deep learning.
Vivaldi Tapered Slot Antenna for Microwave Imaging in Medical Applications Hakim, Randy Ivanal; Mahendra, Daffa; Endarko, Endarko
Jurnal Teknik Elektro Vol 15, No 2 (2023): Jurnal Teknik Elektro
Publisher : Jurusan Teknik Elektro, Fakultas Teknik, Universitas Negeri Semarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15294/jte.v15i2.43955

Abstract

Microwave imaging has become an active research area in recent years, owing primarily to advancements in detecting the early stages of cancer. The study aimed to create a high-gain compact Vivaldi Tapered Slot antenna (VTSA) for microwave imaging in medical applications and also aims to address several challenges in the development of microwave imaging (MWI) technology for medical applications. These challenges include the ability to detect and identify abnormalities in human tissue and considering safe Specific Absorption Rate (SAR) limits for patients, the approach of balancing of penetration and resolution can be done on the design. The antenna operates at frequencies ranging from 1.7 to 3.1 GHz and is built on a low-cost Flame Retardant-4 (FR-4) substrate with a thickness of 1.6 mm. A compact exponential VTSA is initially presented while designing the proposed antenna for broad impedance bandwidth performances. The simulation used a back-to-back linear array of antennas with or without a phantom, specifically a without phantom (only antennas), a water phantom (cube shape), and an anomaly inside the water phantom. The results revealed a significant shift in the signal graph between the three results, indicating a difference in values between the three simulations. A transient domain solver calculation was used in the simulation. The designed antenna improved a gain of 6.09 dBi and a SAR of 0.326 W/kg by maximizing the edges of the exponential in the tapered section and the feedline slot area. The antenna exhibits differences in scattering parameters on each simulation of anomalies across the required frequency range. The result finds suitability of the experiment and simulation in assessing the microwave imaging capabilities. With the data presented, simulated antennas can be used for microwave imaging. The next study should aim on making a suitable imaging system with dimensions that supported in the antenna range and specifications.
Tracing Knowledge States through Student Assessment in a Blended Learning Environment Hidayah, Indriana; Am, Ebedia Hilda
Jurnal Teknik Elektro Vol 15, No 2 (2023): Jurnal Teknik Elektro
Publisher : Jurusan Teknik Elektro, Fakultas Teknik, Universitas Negeri Semarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15294/jte.v15i2.47861

Abstract

Blended learning has recently acquired popularity in a variety of educational settings. This approach has the advantage of being able to autonomously monitor students' knowledge states using the collected learning data. Moodle is the most widely used learning management system in blended learning environments. Students can access Moodle to obtain supplementary materials, exercises, and assessments to complement their face-to-face meetings. However, its performance can be improved by more effectively tailoring students' skills and pace of learning. Several studies have been conducted on knowledge tracing; however, we have not discovered any studies that particularly investigate knowledge tracing in a blended learning setting with Moodle as a component. This study proposes a scheme for assessment using the features of the Moodle quiz platform. The assessment data is used to conduct knowledge tracing with the Bayesian Knowledge Tracing (BKT) model, which improves interpretability. The aforementioned data were collected from information engineering undergraduate students who completed 88 exercises that assessed 23 knowledge components within the course. We measure RMSE and MAE to evaluate the performance of the BKT model on our dataset. Furthermore, we compare the knowledge tracing performance to other well-known datasets. Our results show that the BKT model performed better with our dataset, with an RMSE of 0.314 and an MAE of 0.197. Moreover, the BKT model can be used to assess student performance and determine the level of mastery for each knowledge component. Thus, the outcomes can be applied to personalized learning in the future.
Interference Management Based on Clustering Method for Ultra-Dense Networks in Multicellular Network Gumilang, Alisha Gita; Susanto, Misfa; Fitriawan, Helmy
Jurnal Teknik Elektro Vol 15, No 2 (2023): Jurnal Teknik Elektro
Publisher : Jurusan Teknik Elektro, Fakultas Teknik, Universitas Negeri Semarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15294/jte.v15i2.48738

Abstract

One of solutions to address the increasing demands for data traffic by mobile users is to implement ultra dense network (UDN). UDN consists of many femtocells that are densely deployed on macrocellular communication networks. Since femtocells radius is very short and they are tightly packed, it faces interferences problem i.e., co-tier and cross-tier interferences. This paper proposes interference management technique based on clustering method for UDN multicellular communication networks at downlink transmission. It is purposed to reduce interference effects. To evaluate the proposed clustering method, two simulation scenarios have been designed; namely baseline system and system with the proposed clustering method. The scenarios applied is to randomly distribute femtocells following a uniform distribution in three macrocells areas. Through a clustering algorithm, adjacent femtocells are grouped into one cluster and assigned different frequency channels for each femtocell in that cluster. The same cluster pattern is repeated for all femtocells. Thus, interference effect is canceled within one cluster and reduced among clusters by widening the distance among femtocells that use the same frequency channels. Through simulation experiment, the proposed clustering method is evaluated and compared to the baseline system. The simulation results show that Signal to Interference plus Noise Ratio (SINR) of femtocells increases 0.44 dB, throughput increases 1.67%, Bit Error Rate (BER) reduces, and other parameters improve as well which include spectral efficiency, network energy, and average network energy. The proposed clustering method increases performances of the networks and provides better solution for transmission data speed in densely femtocell network.

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