Vincensius Gunawan
University of Diponegoro

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MAGNETIZATION AND POLARIZATION PROFILE IN PML-TYPE MAGNETOELECTRIC MULTIFERROICS WITH CANTED SPIN SYSTEM Gunawan, Vincensius; Stamps, Robert L
BERKALA FISIKA Vol 15, No 1 (2012): Berkala Fisika
Publisher : BERKALA FISIKA

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Abstract

We calculate the profile of both magnetization and polarization of a PML-typemagnetoelectric multiferroics which allow the magnetization of sub-lattices to be canted.  Thecalculation is started by deriving the Landau energy density and followed by solvingsimultaneously three equilibrium equations which respect to polarization, magnetization andcanting angle.   It is predicted that magnetoelectricity give rise to a “bump” in polarization profile. It is also calculated that the application of a magnetic/an electric field will also influence thepolarization/magnetization of the material.Keywords:  multiferroics, magnetization and polarisation
PEMBUATAN KURVA ISODOSIS 2D DENGAN MENGGUNAKAN KURVA PERCENTAGE DEPTH DOSE (PDD) DAN PROFIL DOSIS DENGAN VARIASI KEDALAMAN UNTUK TREATMENT PLANNING SYSTEM Nurul Ihya, Farhatin; Anam, Choirul; Gunawan, Vincensius
BERKALA FISIKA Vol 16, No 4 (2013): Berkala Fisika
Publisher : BERKALA FISIKA

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Abstract

Treatment Planning System (TPS) is very necessary in radiotherapy planning to give the accurate radiation dose given to the patient.  In the TPS, 2D isodose curve is used to determine thedose distribution with the same rate at a certain distance from the radiation source.  The isodosecurve is obtained from the Percentage Depth Dose (PDD) and dose profile.  Measurement data ofPDD and dose profiles obtained from Kensaras Hospital in Semarang.  The PDD and dose profiledata were obtained from testing the water phantom for soft tissues such as muscles or other bodytissues.  Dose profile curve which is used  is at a various depth, such as: 1.5 cm, 5 cm, 10 cm, 15cm, 20 cm and 25 cm with an area of 5 x 5 cm2field, 10 x 10 cm2, 15 x 15 cm2, 20 x 20 cm, 30 x 30cm2 and 40 x 40 cm2.  At each depth of curve profile, the dose at the surface is calculated  andnormalized using  interpolation and normalized by narrowing techniques. 2D isodose curveobtained from the weighting technique to the calculation of the dose profile curve. In the field sizeof 5 x 5 cm2 and 10 x 10 cm2, isodose curve formed better in the absence of horn at the edge of thecurve.  In the field size larger than 10 x 10 cm2 there are horns on the edge of the curve at thelower depths.Keywords : Treatment Planning System (TPS),  2D Isodose curve, Percentage Depth Dose (PDD),Dose profile.
KOREKSI KURVA ISODOSIS 2D UNTUK JARINGAN NONHOMOGEN MENGGUNAKAN METODE TAR (TISSUE AIR RATIO) Kurniawan, Ryan; Gunawan, Vincensius; Anam, Choirul
YOUNGSTER PHYSICS JOURNAL Vol 3, No 4 (2014): Youngster Physics Journal Oktober 2014
Publisher : YOUNGSTER PHYSICS JOURNAL

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Abstract

Treatment Planning System (TPS) are used to determine the dosedistribution to be received before the irradiation in patients. To see how much radiation dose to be received on the target volume and surrounding critical organs that are required isodose curve. 2D isodose curves correction on non-homogeneous tissues done because in fact the human body not only in the form of soft tissue, but there are also other tissues such as bone tissue or lung. Isodose curve correction have been made using Tissue Air Ratio (TAR) method with Matlab software on a wide field of 10 x 10 cm2. Correction factor is obtained by comparing the effective depth of the TAR with TAR at each depth. Correction factor multiplied by the curve isodose for homogeneous phantom have been obtained from Percentage Depth Dose (PDD) and dose profiles. Corrected isodose curves obtained for nonhomogeneous phantom. Higher the density value on nonhomogeneous phantom, the attenuation will increase and produce the lower dose. Keywords: Treatment Planning System (TPS), 2D Isodose curve, Tissue Air Ratio (TAR), Correction factor, nonhomogeneous tissue, attenuation
PEMBUATAN KURVA ISODOSIS 2D UNTUK BERKAS ELEKTRON ENERGI 5 MeV MENGGUNAKAN PROFILE DOSE DAN KURVA PERCENTAGE DEPTH DOSE (PDD) UNTUK TREATMENT PLANNING SYSTEM RADIOTERAPI Fauzan, Mahfudz; Gunawan, Vincensius; Anam, Choirul
YOUNGSTER PHYSICS JOURNAL Vol 4, No 1 (2015): Youngster Physics Journal Januari 2015
Publisher : Jurusan Fisika, Fakultas Sains dan Matematika, Universitas Diponegoro

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Abstract

Research has been done to make isodose curve of electron beam with the energy of 5 MeV. Isodosis curve performed using PDD curves and dose on broad Profile 10x10 cm2 field; 15x15 cm2; 20x20 cm2; 25x25 cm2, with a depth of 0.5 cm; 1.0 cm; 1.5 cm; 2.0 cm; 2.5 cm. The purpose of this study was to obtain 2D isodose curve shape can be applied to TPS in Radioteraphy.The method which was used to form the isodose curve using PDD curves and dose profiles was done by equalizing the data at each depth using interpolation techniques at intervals of 0.25 cm and normalized to a value of 1, and calculatd the dose at each pixel using the weighting technique that formed isodosis curve with the distribution each depth and broad field. The results show that the PDD curve formed using the interpolation does not affect the magnitude of the dose at different field wide, profile shaped dose showed a dose level at each different depth and normalized to a value of 1 to show the dose at the surface, the isodose curve formation can be applied to compare the isodose curve formed by TPS in Radiotherapy. Keywords: Radiotherapy, Treatment Planning System (TPS), isodose curve, Percentage Depth Dose (PDD), Profile dose
Metode Automatic Clustering dan Fuzzy Logical Relationships untuk Prakiraan Sugiarto, Singgih; Gernowo, Rachmad; Gunawan, Vincensius
JURNAL SISTEM INFORMASI BISNIS Vol 3, No 3 (2013): Volume 3 Nomor 3 Tahun 2013
Publisher : Magister Sistem Informasi

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Abstract

Penelitian mengenai prakiraan dengan menggunakan metode fuzzy time series dalam beberapa kurun waktu terahir ini terus dikembangkan, hal ini dilakukan untuk menutupi kekurangan yang ada pada prakiraan dengan menggunakan metode tradisional. Metode prakiraan tradisional seperti markov, moving average (MA),  dan autoregresive (AR) dapat berjalan untuk memprakirakan data stasioner, tetapi tidak untuk data yang tidak stasioner. Sedangkan auto regresive integrated moving average (ARIMA) dan Box-Jenkins dapat berjalan dengan baik dengan data tidak stasioner. Metode fuzzy time series dapat digunakan dengan baik untuk kedua jenis data tersebut. Salah satu hasil pengembangkan prakiraan fuzzy time series adalah metode automatic clustering dan fuzzy logical relationship yang dalam penelitian ini akan diimplementasikan untuk prakiraan permintaan kredit. Berbeda dengan penelitian sebelumnya, pada penelitian ini hasil prakiraan dapat menghasilkan lebih dari satu periode yang akan datang dengan tujuan untuk mengetahui pengaruh rentang periode terhadap error yang dihasilkan. Selain itu juga dalam penelitian ini jumlah interval dibagi kedalam beberapa sub interval dengan tujuan untuk mengetahui pengaruh pembagian sub interval terhadap error yang dihasilkan.   Kata kunci : Fuzzy time series, automatic clustering dan fuzzy logical relationship
Prediction of 2D Isodose Curve on Arbitrary Field Size in Radiation Treatment Planning System (RTPS) Nugraheni, Dewi Tri; Gunawan, Vincensius; Anam, Choirul
JURNAL SAINS DAN MATEMATIKA Volume 23 Issue 1 Year 2015
Publisher : JURNAL SAINS DAN MATEMATIKA

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Abstract

The study on prediction of 2D isodose curves for atbitrary field size has been done. Isodose curve is very useful for plannning and evaluation of doses received by patients in the radiotherapy treatment. The percentage depth dose (PDD) and dose profiles data for standard field size (square) were obtained from measurements in the Kensaras hospital, Semarang Regency. Dose profiles were taken at a depth of 1.5 cm and a radiation source to skin distance (SSD) of 100 cm. The calculation of PDD data in any field size uses linear interpolation method. While the calculation of the dose profile curve uses the widening, narrowing and weighting interpolation method. Firstly, the calculation of PDD and dose profile for standard field sizes of 3x3, 10x10, 15x15 and 20x20 cm2 were carried out and the results were compared to the measurements. Secondly, the PDD and dose profile for arbitrary field sizes 7x7 dan 13x13 cm2 were calculated. After that, the isodose curves for arbitrary field sizes were generated. The results showed that PDD curves of standard field sizes have maximum deviation values < 5% compared to the measurements. While the dose profile curves for field sizes up from 5x5 cm2 have maximum deviation values approximately 5% which was less than measurement. The profile curve of field size of 3x3 cm2 has maximum deviation value >5%. These results showed that our proposed algorithm was relatively valid. In this study, the PDD, dose profile and isodose curves of arbitrary field sizes 7x7cm2 and 13x13 cm2 were succesfully generated.
The Effect of BaCO3 Compound Changes on the Formation of Magnetic Material BaFe12O19 Priyono, Priyono; Cahyono, Agung; Marhaendrajaya, Indras; Subagio, Agus; Gunawan, Vincensius
JURNAL SAINS DAN MATEMATIKA Volume 23 Issue 4 Year 2015
Publisher : JURNAL SAINS DAN MATEMATIKA

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Abstract

BaFe12O19 is a permanent magnetic material which has superior properties to be excellent until the late of twentieth century. Some of the obstacles in the synthesis of the material using a stoichiometric composition is a difficulty to obtain a single phase and the second phase is always found. This research attempted to make modifications on the initial non-stoichiometric composition by varying the fraction of Ba/Fe through BaCO3 and Fe2O3 compound through solid state reaction mechanism. This solid state reaction was initiated by mixing various fractions of BaCO3 and Fe2O3 powder composition and compacted to produce a homogeneous mixture using a planetary milling. After drying and molding, it was obtained a homogeneous mixture like a cylinder with a diameter of 2:54 cm and a thickness of 0.5 cm. The BaFe12O19 phase was obtained by heating the sample at a temperature of 1200 ° C for 4 hours. To determine changes in the fraction of Ba/Fe before and after sintering, the samples were tested by X-Ray Fluorescence (XRF), while the structure and crystallinity were tested by X-ray diffraction (XRD) and Scanning Electron Microscope (SEM). The results showed that during the heating process, the reduction of barium fractions exceeded 5% from of their initial weight, while changes in the fraction of Fe was not significant. The results of structure and crystallinity measurement showed that the addition a substantial amount of barium carbonate can lead to the decrease of crystallinity from 35.271 nm to 11.265 nm.
The Implementation of Grey Forecasting Model for Forecast Result’s Food Crop Agricultural Muqtadir, Asfan; Suryono, Suryono; Gunawan, Vincensius
Scientific Journal of Informatics Vol 3, No 2 (2016): November 2016
Publisher : Universitas Negeri Semarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15294/sji.v3i2.7912

Abstract

The increasing of the needs of  food crops raised several issues related to land use. The  problems of land used caused by the lack of information related to productivity and eligibility used of land. The goal of this research is to implementation a model of Grey forecasting GM(1,1) to forecast agricultural production, especially in food crops. GM(1,1) is used to built a model with limited data samples and generate good forecasts for short libertine forecasts. This research uses data from the production of food crops for the 2004-2013 it can be calculated by using the model of GM (1,1). The results showed the model GM (1,1) can produce highly accurate forecasts, from the experimental results for pattern trends generate value ARPE 5.74% or accuracy of forecasts reached 94.26% in crop production.
The Electric Susceptibility of Bi-Layers Ferroelectrics Gunawan, Vincensius; Umiati, Ngurah Ayu Ketut; Subagio, Agus
Journal of Physics and Its Applications Vol 1, No 2 (2019): May 2019
Publisher : Diponegoro University Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1356.387 KB) | DOI: 10.14710/jpa.v1i2.4860

Abstract

In order to enhance insight of layered structure, we perform numerical calculation to obtain the dynamic electric susceptibility in bi-layers ferroelectrics. Since susceptibility is a parameter which gives response to the external field, then determination of this parameter is important. A lattice model is employed to slice bilayer structure into several lattices.  Then, Landau-Khalatnikov equation of motion is used in each lattice to construct a matrix equation of equation of motion.  The solution is obtained by applying entire-cell effective medium.  We find that the homogeneity of dynamic polarization is different from homogeneity of the single individual layer due to the existence of interlayer interaction.  As a result, the electric susceptibility is also altered.  It is also noticed that there is a relation between the homogeneity of dynamic polarization and the value of electric susceptibility near resonant frequency.  The higher the homogeneity, the bigger the values of susceptibility will be.