Sukru Ozen - Profile on Academia.edu (original) (raw)

Papers by Sukru Ozen

Electromagnetic field exposure to human head model with various metal objects at sub-6 GHz frequencies

Electromagnetic Biology and Medicine, Jun 4, 2023

Corrosion potential and electromagnetic shielding effectiveness of geopolymer tiles produced with waste metal particles

Sadhana-academy Proceedings in Engineering Sciences, Jun 15, 2022

The developmental effects of extremely low frequency electric fields on visual and somatosensory evoked potentials in adult rats

Electromagnetic Biology and Medicine, Dec 11, 2014

Abstract The purpose of our study was to investigate the developmental effects of extremely low f... more Abstract The purpose of our study was to investigate the developmental effects of extremely low frequency electric fields (ELF-EFs) on visual evoked potentials (VEPs) and somatosensory-evoked potentials (SEPs) and to examine the relationship between lipid peroxidation and changes of these potentials. In this context, thiobarbituric acid reactive substances (TBARS) levels were determined as an indicator of lipid peroxidation. Wistar albino female rats were divided into four groups; Control (C), gestational (prenatal) exposure (Pr), gestational+ postnatal exposure (PP) and postnatal exposure (Po) groups. Pregnant rats of Pr and PP groups were exposed to 50 Hz electric field (EF) (12 kV/m; 1 h/day), while those of C and Po groups were placed in an inactive system during pregnancy. Following parturition, rats of PP and Po groups were exposed to ELF-EFs whereas rats of C and Pr groups were kept under the same experimental conditions without being exposed to any EF during 68 days. On postnatal day 90, rats were prepared for VEP and SEP recordings. The latencies of VEP components in all experimental groups were significantly prolonged versus C group. For SEPs, all components of PP group, P2, N2 components of Pr group and P1, P2, N2 components of Po group were delayed versus C group. As brain TBARS levels were significantly increased in Pr and Po groups, retina TBARS levels were significantly elevated in all experimental groups versus C group. In conclusion, alterations seen in evoked potentials, at least partly, could be explained by lipid peroxidation in the retina and brain.

European Signal Processing Conference, Sep 1, 2005

The wavelet transform is one of the important methods that are used to minimize noises and to ana... more The wavelet transform is one of the important methods that are used to minimize noises and to analyze signals. The choice of wavelet and its associated scaling function are very important to obtain the most useful wavelet transforms. In the present work, it was investigated that the easy obtaining of the P and S phases by minimizing the noise at the three-component seismograms displacement records using Daubechies Discrete Wavelet Transform. The after shocks of the earthquake that occurred at the Afyon-Sultandağ (Turkey) on 03-04 February 2002 were used as real data. This work shows that the Daubechies Discrete Wavelet Transform gives very successful results at determining the P and S seismic phases without deforming the main characteristics of the required signal, thus making the data more comprehensible.

Magnetic field risk analysis for employees and patients due to power transformers in hospital buildings

2017 Progress In Electromagnetics Research Symposium - Spring (PIERS), May 1, 2017

In this study, magnetic field levels are analysed for high power capacity transformers in hospita... more In this study, magnetic field levels are analysed for high power capacity transformers in hospital buildings. Measurements were taken in the inspection and patient admission units which are located around the transformer station. Magnetic field levels are measured as 1–4.67 μΤ in the transformer room and 1.74–27 μΤ in the control room. In the orthopaedic poly-clinic room located at the top of the transformer room, magnetic field intensity values vary in the range of 0.451–2.15 μΤ. The results are compared with ICNIRP occupational and general public (International Commission on Non-Ionizing Radiation Protection) electromagnetic safety guidelines. Electromagnetic risks for employees and patients are evaluated, and the measures to carry the magnetic field levels to safety limits are determined.

Journal of Microwave Power and Electromagnetic Energy, Jul 19, 2023

Carbon fiber reinforced multilayered (PyC-SiC) n matrix (C/(PyC-SiC) n ) composites were fabricat... more Carbon fiber reinforced multilayered (PyC-SiC) n matrix (C/(PyC-SiC) n ) composites were fabricated by alternately depositing PyC and SiC inside preforms via isothermal chemical vapor infiltration. A four-layer structure consisting of alternate PyC and SiC was formed compactly on the surface of carbon fibers. The electromagnetic interference shielding effectiveness (SE) in the frequency range of 8.2-12.4 GHz of the composites was investigated. The composites showed a high SE value of about 40 dB in the whole frequency band due to the repeated reflection and dissipation of electromagnetic wave between the interfaces of SiC layers and PyC layers, PyC layers and carbon fibers. Therefore, C/(PyC-SiC) n composites exhibited great potential as functional materials.

Increased Hippocampal Level of Kinases after Long-term Exposure to GSM-2100 Cell Phone Radiation

Humans in modern society utilize cell phones, with interest expected to increment constantly in c... more Humans in modern society utilize cell phones, with interest expected to increment constantly in coming years. Cell phone users partly absorb electromagnetic radiation (EMR) through signals from cellular phones. Therefore, understanding the biological effects of radiofrequency electromagnetic radiation (RF-EMR) exposure is very important for human health. Owing to close proximity use of cell phones to user's head, human brain is adversely affected. One of the affected brain regions is known as hippocampus. The major intracellular signalling pathway implemented in the hippocampus includes activation-dependent molecular changes which are mediated by a rise in intracellular calcium leading to the activation of protein kinases. In the literature, little is known about the effects of long term GSM-2100 cell phone radiation exposure on hippocampal levels of kinases including Ca2+/calmodulin-dependent protein kinase II (CaMKII) and protein kinase A (PKA) on rats. Hence, the present study has been focused on 3G cell phone radiation effects on hippocampal level of kinases with 50 days of exposure. Rats were divided into “sham-exposed” and “GSM-2100 exposed” groups. Sham-exposed rats were housed in the same room under the same conditions with equal time period without antenna. GSM-2100 exposure group of rats were exposed to 2100MHz RF-EMR emitted from the signal generator for 2 hours per day. Hippocampal level of kinases was determined by western blotting. The comparison of hippocampal levels of CaMKIIα and PKA between “sham-exposed” and “GSM-2100 exposed” groups revealed that hippocampal levels of these kinases were significantly higher in “GSM-2100 exposed” groups than “sham-exposed” groups. Our results provide experimental data suggesting that long term exposure to GSM-2100 cell phone radiation had increased effect on hippocampal kinases which might encourage further research investigating molecular effects of RF-EMR exposure on signaling pathways in the central nervous system.

Effects of 2G mobile phone exposure on both behavioural performance and levels of enzyme from NMDA-dependent pathway

Mobile communications are expanded day by day and bring along their potential adverse effects on ... more Mobile communications are expanded day by day and bring along their potential adverse effects on human brain. One of the affected brain regions is known as hippocampus which is the most studied structure because of its well documented role in learning and memory. The major intracellular signaling pathway implemented in memory formation in the hippocampus is N-methyl-D-aspartate (NMDA)-dependent pathway including activation of kinases. Experimental animal studies have demonstrated several effects of short and/or long term RF-EMR exposure on cognitive functions and behaviors of animals. In the literature, little is known about the effects of RF-EMR exposure on NMDA receptor signalling pathway. Therefore, in the present study an attempt was taken to demonstrate possible effects of acute and chronic 900 MHz RF-EMR exposure on both passive avoidance behavior and hippocampal level of the enzymes from NMDA receptor related signalling pathway including p44/42 MAPK and it is phosphorylated form (phopsho p44/42 MAPK) using Western Blotting technique. Rats were divided into following groups: Sham rats, rats exposed to 900 MHz RF-EMR for 2h/day for 1 (acute) or 10 (chronic) weeks, respectively. Overall results indicated that both acute and chronic exposure to 900 MHz RF-EMR can impair passive avoidance behavior with minor effect on behavior of chronic group of rats. In addition, hippocampal levels of both p44/42 MAPK and phopsho p44/42 MAPK were significantly higher in chronic group of rats. These findings demonstrated that different duration time (1 week versus 10 weeks) of 900 MHz RF-EMR exposure has different effects on both passive avoidance behavior of rats and hippocampal levels of p44/42 MAPK and phopsho p44/42 MAPK from NMDA dependent pathway.

Tipik bir Endüstriyel Tesiste Enerji Verimliliği Hesapları

ENDÜSTRİDE YÜKSEK VERİMLİ MOTOR KULLANIMININ ENERJİ VERİMLİLiGiNE ETKİLERİ

Sakarya Üniversitesi Fen Bilimleri Enstitüsü Dergisi, Jun 1, 2004

Bu calismada endustride kullanilan motorlarin enerji ve guc kayiplan incelenmis, siniflandirilmis... more Bu calismada endustride kullanilan motorlarin enerji ve guc kayiplan incelenmis, siniflandirilmis ve siandart verimli motorlar yerine, enerji kaybi dusuk yuksek verimli motorlarin kullanilmasinin sanayi tesi slerindeki enerji tasarrufuna etkisi arastirilmistir. Bunun mali degerinin hesaplanmasi icin gerekli prosedurler aciklanmistir. Bu prosedurler hali hazirda isleyen bir sanayi tesisindeki motorlar uzerinde uygulan mis enerji tasarruf miktari ,tasa rrufun mali karsiligi, yatirim tutari ve geri odeme surelerinin hesaplanmasi verilmistir. Bu veriler isiginda hangi degerlerdeki yuksek verimli motorlarin kullanilabilecegi belirlenmistir.

Güneş Enerjisi Santrallerinde Elektromanyetik Alan Seviyeleri ve Mesleki Maruziyet Analizi

Mühendislik bilimleri ve tasarım dergisi, Sep 15, 2019

Son yıllarda uydu yayın sistemleri, mikrodalga fırınlar, indüksiyon fırınları, polis ve ordu rada... more Son yıllarda uydu yayın sistemleri, mikrodalga fırınlar, indüksiyon fırınları, polis ve ordu radar sistemleri, tıbbi görüntüleme gibi elektromanyetik cihazların kullanımının hızlı bir şekilde artmasıyla insanlar sürekli elektromanyetik dalgalara maruz kalmaktadır. Özellikle endüstride kullanılan yüksek güçlü mikrodalga kaynakları çalışan sağlığı üzerinde ciddi riskler oluşturmaktadır. İndüksiyon fırını ve buna benzer cihazların gerek hatalı kullanımı gerekse cihazlarda meydana gelen kaçaklar nedeniyle cihazı kullanan operatörlerin beyin, göz ve deri dokusunda ciddi hasarlar meydana gelebilmektedir. Bu çalışmada, endüstriyel mikrodalga kaynaklarının çalışma frekansları olan 915 ve 2450 MHz frekanslarında dokularda oluşan SAR değerleri ve sıcaklık artışı, çok katmanlı doku modeli kullanılarak hesaplanmıştır. Analitik analizler MATLAB programı yardımıyla ayrı ayrı yapılmıştır. Elde edilen sonuçlar, tıbbi güvenlik limit değerleriyle karşılaştırılmış ve limit değerlerin altında olduğu tespit edilmiştir.

Osmaniye Korkut Ata Üniversitesi Fen Bilimleri Enstitüsü Dergisi

Günümüzde elektrikli araçların batarya performansı tartışma konusu olsa da şarj istasyonlarının ç... more Günümüzde elektrikli araçların batarya performansı tartışma konusu olsa da şarj istasyonlarının çoğalması bu soruna bir çözüm olmuştur. Kablosuz güç transferi (KGT) yöntemi, elektrikli araç sektöründe yenilikçi teknolojilerden birisidir. Bu çalışmada, seri – seri topolojiye sahip manyetik rezonans kuplaj temelli KGT yöntemi, teorik ve deneysel olarak ele alınmıştır. Devre için tasarlanan bobinlerin arası 15 cm iken 40 kHz’de yaklaşık 36 W aktarılmıştır. Devrenin simülasyon sonuçları ile deneysel ölçümlerinin birbirini desteklediği gözlenmiştir. Ayrıca, söz konusu devre ile bir elektrikli arabanın bataryasının şarjı esnasında oluşan elektromanyetik alan maruziyeti incelenmiştir. Ansys HFSS ile gerçekleştirilen simülasyonlar sonucunda doku modelindeki en yüksek elektrik alan seviyesi yaklaşık 43 mV/m olarak elde edilmiştir. Tasarlanan KGT devresinin manyetik alan şiddeti ölçümleri sonucunda alıcı bobine yük olarak sadece batarya bağlı durumdayken 5 cm mesafede 11 μT ölçülmüştür. Yük o...

Analysis and Measurement of the Electromagnetic Shielding Efficiency of the Multi-Layered Carbon Fiber Composite Fabrics

2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring), 2019

Due to the individual behaviors and characteristics of composites, the usage areas of composites ... more Due to the individual behaviors and characteristics of composites, the usage areas of composites have expanded owing to the development of material science in recent years. In this study, electromagnetic shielding efficiency of carbon fiber composite fabrics, which are the one of the most widely used worldwide composite materials due to their electrical and mechanical properties, have been studied. Material samples were chosen as plain woven, twill woven and unidirectional polyacrylonitrile (PAN) based carbon fiber composites. The chosen carbon fiber fabric samples were investigated as both single layer and multilayer structure. Electromagnetic shielding measurements were carried out through vector network analyzer (VNA) in the frequency range of 3.3–4.9 GHz (S-C band). Single layer carbon fiber composite fabric samples were evaluated according to woven type, thickness and orientation. As a result of the evaluations, it was observed that different types of mesh structure caused a change in electromagnetic shielding efficiency. In order to investigate the effect of thickness for electromagnetic shielding efficiency, twill woven with the thicknesses of both 0.327 mm and 0.65 mm was measured. Electromagnetic shielding efficiency was increased while the thickness of the sample was increase, as it was expected. It was observed that the orientation did not affect significantly electromagnetic shielding efficiency of the plain woven and the twill woven samples. But, orientation was a substantial factor for the electromagnetic shielding efficiency of unidirectional structure. In multilayer structures, double and triple layered models of plain woven, twill woven and unidirectional woven fabrics, whose thicknesses are 0.327 mm, 0.327 mm and 0.48 mm respectively, were examined. The results showed that double and triple layered structures exhibited more than 80 dB and 90 dB electromagnetic shielding efficiency respectively.

The wavelet transform is one of the most important method used in signal processing. In this stud... more The wavelet transform is one of the most important method used in signal processing. In this study, we have introduced frequency-energy characteristics of local earthquakes using discrete wavelet transform. Frequency-energy characteristic was analyzed depend on difference between P and S wave arrival time and noise within records. We have found that local earthquakes have similar characteristics. If frequency-energy characteristics can be found accurately, this gives us a hint to calculate P and S wave arrival time. It can be seen that wavelet transform provides successful approximation for this. In this study, 100 earthquakes with 500 records were analyzed approximately.

The N-methyl-D-aspartate (NMDA)-dependent pathway is the major intracellular signaling pathway im... more The N-methyl-D-aspartate (NMDA)-dependent pathway is the major intracellular signaling pathway implemented in both short- and long-term memory formation in the hippocampus which is the most studied brain structure because of its well documented role in learning and memory. However, little is known about the effects of RF-EMR exposure on NMDA receptor signaling pathway including activation of protein kinases, notably Ca<sup>2+</sup>/calmodulin-dependent protein kinase II alpha (CaMKIIα). The aim of the present study was to investigate the effects of acute and chronic 900 MHz RF-EMR exposure on both passive avoidance behaviour and hippocampal levels of CaMKIIα and its phosphorylated form (pCaMKIIα). Rats were divided into the following groups: Sham rats, and rats exposed to 900 MHz RF-EMR for 2 h/day for 1 week (acute group) or 10 weeks (chronic group), respectively. Passive avoidance task was used as a behavioural method. The hippocampal levels of selected kinases were me...

Elektromanyetik girisimin onlenmesinde temel cozum yontemlerinden birisi olan ekranlama elektroma... more Elektromanyetik girisimin onlenmesinde temel cozum yontemlerinden birisi olan ekranlama elektromanyetik uyumluluk kapsaminda en onemli basliklardan birisidir. Uygulamada ve elektromanyetik uyumluluk literaturunde ekran konusu daha cok ekran etkinligi temelinde pratik yaklasimlarla ele alinmakta, Maxwell denklemlerine dayali detayli cozumlere cok az yer verilmektedir. Oysa ekranlama teorisinin iyi anlasilabilmesi icin, Maxwell denklemlerini temel alan detayli cozumlerin yapilmasi gerekmektedir. Bu temel ihtiyac dikkate alinarak, genel silindir ekran modelinde elektromanyetik alan ifadeleri analitik olarak cozulmus, elektrik ve manyetik alana karsi ekranlama etkinliginin analizi yapilmistir. Genel silindir ekran modelinde elektromanyetik alan icin ekran etkinligi, ekran parametreleri ve frekansa bagli olarak incelenmistir.

Electromagnetic Biology and Medicine, 2020

The present study evaluated whether short-term exposure to different doses of 2.1 GHz radiofreque... more The present study evaluated whether short-term exposure to different doses of 2.1 GHz radiofrequency electromagnetic radiation (RF-EMR) has different effects on rats' behaviour and hippocampal levels of central cholinergic biomarkers. Animals were divided into three equal groups namely; group 1 was sham-exposed group, group 2-3 were exposed to 45 V/m and 65 V/m doses of 2.1 GHz frequency for 1 week respectively. Numerical dosimetry simulations were carried out. Object location and Y-maze were used as behavioural tasks. The protein and mRNA expression levels of AChE, ChAT, and VAChT, in the hippocampus were tested using Western Blotting and Real-Time PCR. The impairment performance of rats subjected to 65 V/m dose of 2.1 GHz RF-EMR in both object location and Y-maze tasks was observed. The hippocampal levels of AChE, ChAT, and VAChT, were significantly lower in rats exposed to 65 V/m dose of 2.1 GHz RF-EMR than others. The stronger effect of "65 V/m" dose on both rat's hippocampal-dependent behavioural performances and hippocampal levels of cholinergic biomarkers may be due to the stronger effect of "65 V/m" dose where rats' snouts were located at the nearest distance from the monopole antenna. Furthermore, the simulated SAR values were high for 65 V/m electric-field strengths. For the first time, we report the potential dose-dependent effects of short-term exposure to 2.1 GHz radiation on rat's behavioural performances as well as hippocampal levels of cholinergic biomarkers. Further studies are needed to understand the mechanisms by which RF-EMR influences the function of the central cholinergic system in the brain.

TURKISH JOURNAL OF ELECTRICAL ENGINEERING & COMPUTER SCIENCES, 2017

In recent years, increasing energy demand has resulted in more loading in power transmission line... more In recent years, increasing energy demand has resulted in more loading in power transmission lines and correspondingly more electric and magnetic field occurrence. In this paper, electric and magnetic field levels around high voltage power transmission lines are measured and then calculated analytically by simulating the realistic case. Moreover, the field levels around these power lines have been predicted using multilayer perceptron artificial neural network (ANN) and generalized regression neural network models. Typical 154 kV power transmission line facilities of Turkey have been studied. Electric and magnetic field levels in the proximity of power transmission lines have been predicted with ANN models with high accuracies. Particularly, the MLPNN algorithm predicts the electric and magnetic field intensities with very high precision. The aim of this research is to create a reference for researchers focused on topics of occupational and general public exposures and also biological effects of electric and magnetic fields emitted from low-frequency power transmission lines.

Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2019

In this study, gelatin-based conductive hydrogels doped with carbon nanotube (CNT), poly (3,4-eth... more In this study, gelatin-based conductive hydrogels doped with carbon nanotube (CNT), poly (3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and silver (Ag) nanoparticle were prepared for use in biopotential measurements. Gelatin was modified by various concentrations of methacrylic anhydride (MA) to obtain photocrosslinkable gelatin methacrylate (GelMA) polymer with low (21%), medium (44%) and high (78%) methacrylation degree. Chemical modification of gelatin was characterized by 1 H-NMR spectroscopy. It was observed that mechanical properties of the GelMA hydrogels were highly dependent on methacrylation degree. Ultimate compressive stress of low, medium and high methacrylated gelatin hydrogel was measured to be 9.97 ± 0.14 kPa, 17.83 ± 1.73 kPa and 38.23 ± 2.96 kPa, respectively. Surface morphology of hydrogels was visualized by scanning electron microscope (SEM). The pore size of methacrylated gelatin hydrogel significantly reduced with the addition of CNT, PEDOT:PSS and Ag nanoparticle into the hydrogel matrix. The results of thermal gravimetric analysis showed that conductive hydrogels were of higher thermal stability than nonconductive GelMA hydrogel. The suitability of the prepared hydrogels for biopotential measurements was determined by equivalent impedance measurements. Impedance values of hydrogel samples were obtained in the frequency range of 20 Hz-500 Hz. The hydrogel materials prepared in this study exhibited high impedance at low frequencies and low impedance at high frequencies. The results of this study showed that the hydrogels produced with Ag nanoparticle are more suitable electrode materials for physiological measurement systems such as electrocardiography (ECG) and electroencephalography (EEG).