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Spektra: Jurnal Fisika dan Aplikasinya

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Published by Universitas Negeri Jakarta

ISSN : 25413384 EISSN : 25413392 DOI : -

Core Subject : Science, Engineering,

Aerospace Engineering Electrical & Electronics Engineering Energy Materials Science & Nanotechnology Physics

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Articles 260 Documents

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ANALYSIS OF THE EFFECT OF CARE DOSE 4D SOFTWARE USE ON IMAGE QUALITY AND RADIATION DOSE ON THE CT SCAN ABDOMEN Kartika Sari, Ni Larasati; Suzana, Merry; Muslim, Muzilman; Muliyati, Dewi
Spektra: Jurnal Fisika dan Aplikasinya Vol. 5 No. 1 (2020): SPEKTRA: Jurnal Fisika dan Aplikasinya, Volume 5 Issue 1, April 2020
Publisher : Program Studi Fisika Universitas Negeri Jakarta

The CT Scan is the most significant contributor to radiation dose on radiological examination, although the frequency of the examination is far below other modalities. In order to control this radiation dose, manufactures of CT Scan have equipped their units with built-in software called Automatic Exposure Control (AEC). This study aims to analyze the effect of AEC software, CARE Dose 4D, on image quality, and CTDIvol. Objects used in this study were three water phantoms, each with a diameter of 165 mm, 230 mm, and 305 mm. The image quality-analyzed was CT Number and noise. Measurement of image quality was carried out following Bapeten's provisions. Noise Power Spectrum (NPS) graphics were also used to further observes noise texture. The CT Number accuracy, CT Number, and noise uniformity obtained with and without CARE Dose 4D, on the three phantoms were still within Bapeten's threshold. This indicates that the use of CARE Dose 4D can still image a homogeneous object accurately. The results of the NPS curve showed that the two modes, in three phantoms, were having the same noise texture. The NPS curves also showed that the use of CARE Dose 4D produces higher noise than the non-CARE Dose 4D mode. Meanwhile, there were significant differences from the CTDIvol obtained from the two modes. The use of CARE Dose 4D software reduced dose of up to 54.34%. From this, the use of CARE Dose 4D software can reduce the radiation dose while maintaining image quality.

THE DETERMINATION OF BARIUM STRONTIUM TITANATE THIN FILM BAND GAP ENERGY Ba0,15Sr0,85TiO3 USING ULTRAVIOLET-VISIBLE SPECTROSCOPY Rahmi Dewi; Krisman Krisman; Zulkarnaen Zulkarnaen; Rahmi Afrida Syahraini; TS Luqman Husein
Spektra: Jurnal Fisika dan Aplikasinya Vol 5 No 1 (2020): SPEKTRA: Jurnal Fisika dan Aplikasinya, Volume 5 Issue 1, April 2020
Publisher : Program Studi Fisika Universitas Negeri Jakarta

A thin layer of Barium Strontium Titanate Ba0.15Sr0.85TiO3 (BST) was developed on a glass substrate using a sol-gel method with annealing temperatures and spin coating process at 3500 rpm for 30 seconds. The annealing temperature varied from 600oC, 650oC, and 700oC. Characterization of optical properties was developed using UV-Vis spectroscopy to determine the energy bandgap. The values of the BST thin layer energy band at the annealing temperature were 3.55 eV, 3.32 eV, and 3.10 eV, respectively. The results indicate that the BST thin film was a semiconductor material.

BACK MATTER SPEKTRA VOLUME 4 ISSUE 1, APRIL 2019 Editor Spektra
Spektra: Jurnal Fisika dan Aplikasinya Vol 4 No 1 (2019): SPEKTRA: Jurnal Fisika dan Aplikasinya, Volume 4 Issue 1, April 2019
Publisher : Program Studi Fisika Universitas Negeri Jakarta

BACK MATTER SPEKTRA VOLUME 4 ISSUE 2, AUGUST 2019 Editor Spektra
Spektra: Jurnal Fisika dan Aplikasinya Vol 4 No 2 (2019): SPEKTRA: Jurnal Fisika dan Aplikasinya, Volume 4 Issue 2, August 2019
Publisher : Program Studi Fisika Universitas Negeri Jakarta

BACK MATTER SPEKTRA VOLUME 4 ISSUE 3, DECEMBER 2019 Editor Spektra
Spektra: Jurnal Fisika dan Aplikasinya Vol 4 No 3 (2019): SPEKTRA: Jurnal Fisika dan Aplikasinya, Volume 4 Issue 3, December 2019
Publisher : Program Studi Fisika Universitas Negeri Jakarta

THE OUTBREAK’S MODELING OF CORONAVIRUS (COVID-19) USING THE MODIFIED SEIR MODEL IN INDONESIA Rustan Rustan; Linda Handayani
Spektra: Jurnal Fisika dan Aplikasinya Vol 5 No 1 (2020): SPEKTRA: Jurnal Fisika dan Aplikasinya, Volume 5 Issue 1, April 2020
Publisher : Program Studi Fisika Universitas Negeri Jakarta

Coronavirus Disease 2019 (COVID-19) is an infectious disease caused by a new type of virus called SARS-CoV-2, and by the beginning of 2020 had spread throughout the world, including Indonesia. A high rate of spread of COVID-19 causes the number of patients that infected increase significantly. In this study, mathematical modeling was carried out to predict the number of COVID-19 patients and the duration of the COVID-19 pandemic in Indonesia. The model used is a modified SEIR model (Susceptible, Exposed, Infected, Recovered) with several assumptions such as a constant and homogeneous population, patients who have recovered can not be infected, and the spread only occurs from human to human. In addition, it is assumed that there are individuals who carry out quarantine and isolation. Modeling is done using the help of MATLAB R2015a. The modeling results show that the peak of the COVID-19 pandemic in Indonesia will occur in the middle of May 2020, and the number of infected patients will be about 15000 people. This amount can be reduced if the quarantine and self-isolation process is carried out optimally.

FRONT MATTER SPEKTRA VOLUME 5 ISSUE 1, APRIL 2020 Editor Spektra
Spektra: Jurnal Fisika dan Aplikasinya Vol 5 No 1 (2020): SPEKTRA: Jurnal Fisika dan Aplikasinya, Volume 5 Issue 1, April 2020
Publisher : Program Studi Fisika Universitas Negeri Jakarta

BACK MATTER SPEKTRA VOLUME 5 ISSUE 1, APRIL 2020 Editor Spektra
Spektra: Jurnal Fisika dan Aplikasinya Vol 5 No 1 (2020): SPEKTRA: Jurnal Fisika dan Aplikasinya, Volume 5 Issue 1, April 2020
Publisher : Program Studi Fisika Universitas Negeri Jakarta

SIMULATION OF PEAK GROUND ACCELERATION AND PSEUDO SPECTRAL ACCELERATION OF PALU EARTHQUAKE SEPTEMBER 28TH 2018 Amalia Nasruroh; Bambang Sunardi; Muhammad Fikri Hayqal Hiola; Hendri Subakti
Spektra: Jurnal Fisika dan Aplikasinya Vol 6 No 1 (2021): SPEKTRA: Jurnal Fisika dan Aplikasinya, Volume 6 Issue 1, April 2021
Publisher : Program Studi Fisika Universitas Negeri Jakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21009/SPEKTRA.061.06

The devastating earthquake Mw 7.4 hit Palu City, Central Sulawesi on September 28th, 2018, at 17:02:44 WIB. A high tsunami followed it. More than 2000 people died as a result of the earthquake and tsunami disaster. The latest evidence shows that the earthquake was categorized as a rare super shear earthquake. The earthquake shaking that hit Palu City is relatively large. Acceleration data are not available at the study site due to the lack of instrumentation in the area. The Authors present a simulation of peak ground acceleration (PGA) and pseudo-spectral acceleration (PSA) due to the earthquake in three locations Tatura Mall, Roa-Roa Hotel, and Antapura Hospital. PGA describes the maximum acceleration on the ground, while pseudo-spectral acceleration describes the acceleration of earthquake shaking from buildings with various floor numbers. Simulation of PGA and PSA to the three sites used three different Ground Motion Prediction Equation (GMPE) functions, BSSA14, CB14, and CY14, with the weighting of each Next Generation Attenuation (NGA) GMPE functions. The results of PGA simulation is about 0.22-0.23 g and show that in the three study site, it is more vulnerable to spectral acceleration period T=0.3 s or building with three floors or about 1-15 floors. These correlate with the level of damage caused by earthquakes which is more impact to relatively higher buildings.

THE EFFECT OF COBALT CONTENT ON MAGNETIC PROPERTIES OF CoFe ALLOYS Widia Nursiyanto; L. Rohman; M. Alfatun N.; E. Purwandari
Spektra: Jurnal Fisika dan Aplikasinya Vol 5 No 2 (2020): SPEKTRA: Jurnal Fisika dan Aplikasinya, Volume 5 Issue 2, August 2020
Publisher : Program Studi Fisika Universitas Negeri Jakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21009/SPEKTRA.052.01

Hard Disk Drive (HDD) as a data storage device when operated with high temperatures (around 66oC), its function will be constrained. The CoFe alloys have a large coercivity field and can be patterned in very small sizes that are suitable for HDD devices. In this study, Co1-x Fex cube alloy was used (x = 0.25; 0.30; 0.50; 0.75). Samples were treated with temperature changes to get the Curie temperature. The coercivity field value is obtained by giving the external field and temperature below Curie temperature and also above Curie temperature to the samples. The VAMPIRE software is a micromagnetic simulation program based on atomistic models. The results showed that Curie’s temperature decreased when Co content increased. The composition of Co0.25 Fe0.75 has the highest Curie temperature that is equal to 1075 K. The temperature Curie is not affected by the size of the cube. When the sample is given a temperature rise below the Curie temperature, the value of the coercivity field decreases. The value of the coercivity field is very difficult to determine when the temperature used is above the Curie temperature. The percentage of composition does not affect the coercivity field value. Therefore, cube-shaped CoFe material is very suitable for use as a material data storage device operated at temperatures below the Curie.

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