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- 저자 : Karaarslan (검색결과 12 건)
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Karaarslan, Korhan,Arifoglu, Birol,Beser, Ersoy,Camur, Sabri The Korean Institute of Electrical Engineers 2018 Journal of Electrical Engineering & Technology Vol.13 No.2
This paper presents a single-phase asymmetric half-bridge cascaded multilevel inverter based series active power filter (SAPF) for harmonic voltage compensation. The effect of level number on performance of the proposed SAPF is examined in terms of total harmonic distortion (THD) and system efficiency. Besides, the relationship between the level number and the number of switching device are compared with the other multilevel inverter topologies used in APF applications. The paper is also aimed to demonstrate the capability of the SAPF for compensating harmonic voltages alone, without using a passive power filter (PPF). To obtain the required output voltage, a new switching algorithm is developed. The proposed SAPF with levels of 7, 15 and 31 is used in both simulation and experimental studies and the harmonic voltages of the load connected to the point of common coupling (PCC) is compensated under two different loading conditions. Furthermore, very high system efficiency values such as 98.74% and 96.84% are measured in the experimental studies and all THD values are brought into compliance with the IEEE-519 Standard. As a result, by increasing the level number of the inverter, lower THD values can be obtained even under high harmonic distortion levels while system efficiency almost remains the same.
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Half-bridge Cascaded Multilevel Inverter Based Series Active Power Filter
Karaarslan, Korhan,Arifoglu, Birol,Beser, Ersoy,Camur, Sabri The Korean Institute of Power Electronics 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.3
A new single phase half-bridge cascaded multilevel inverter based series active power filter (SAPF) is proposed. The main parts of the inverter are presented in detail. With the proposed inverter topology, any compensation voltage reference can be easily obtained. Therefore, the inverter acts as a harmonic source when the reference is a non-sinusoidal signal. A 31-level inverter based SAPF with the proposed topology, is manufactured and the voltage harmonics of the load connected to the point of common coupling (PCC) are compensated. There is no need for a parallel passive filter (PPF) since the main purpose of the paper is to represent the compensation capability of the SAPF without a PPF. It is aimed to compensate the voltage harmonics of the load fed by a non-sinusoidal supply using the proposed inverter. The validity of the proposed inverter based SAPF is verified by simulation as well as experimental study. The system efficiency is also measured in this study. Both simulation and experimental results show that the proposed multilevel inverter is suitable for SAPF applications.
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Half-bridge Cascaded Multilevel Inverter Based Series Active Power Filter
Korhan Karaarslan,Birol Arifoglu,Ersoy Beser,Sabri Camur 전력전자학회 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.3
A new single phase half-bridge cascaded multilevel inverter based series active power filter (SAPF) is proposed. The main parts of the inverter are presented in detail. With the proposed inverter topology, any compensation voltage reference can be easily obtained. Therefore, the inverter acts as a harmonic source when the reference is a non-sinusoidal signal. A 31-level inverter based SAPF with the proposed topology, is manufactured and the voltage harmonics of the load connected to the point of common coupling (PCC) are compensated. There is no need for a parallel passive filter (PPF) since the main purpose of the paper is to represent the compensation capability of the SAPF without a PPF. It is aimed to compensate the voltage harmonics of the load fed by a non-sinusoidal supply using the proposed inverter. The validity of the proposed inverter based SAPF is verified by simulation as well as experimental study. The system efficiency is also measured in this study. Both simulation and experimental results show that the proposed multilevel inverter is suitable for SAPF applications.
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Serap Karaarslan,Banu Yaman,Hakan Ozturk,Banu Sarsik Kumbaraci 대한병리학회 2015 Journal of Pathology and Translational Medicine Vol.49 No.5
Background: Parafibromin is a recently defined tumor suppressor gene. The aim of our study was to determine the relationships of parafibromin expression in urothelial carcinomas (UCs) with prognostic parameters and to evaluate the use of parafibromin as a potential marker of UC. Methods: Parafibromin expression was assessed in 49 UC specimens using immunohistochemistry. The correlations between parafibromin expression and clinical and pathologic parameters were investigated. Results: Of the patients, 42 (85.7%) were male, and the mean age was 69.6 ± 8.2 years (range, 54 to 88 years). Morphologically, the UCs were divided into two groups: papillary (n = 27) and non-papillary (n = 22). There were seven low-grade (14.3%) and 42 high-grade (85.7%) tumors. Parafibromin was negative in 13 tumors (26.5%), partially positive in 19 tumors (38.8%), and positive in 17 tumors (34.7%). Parafibromin expression was more negative in UCs from upper urinary locations (n = 17) and with muscularis propria invasion (n = 28), which was statistically significant (p = .009 and p = .007, respectively). There was no statistically significant relationship between parafibromin expression and gender, age, tumor grade, survival, or disease-free survival. Conclusions: We found that UC cases with parafibromin positivity had less of a tendency to show muscularis propria invasion and were more commonly located in the lower urinary system. These results need to be confirmed with studies based on larger case series.
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Korhan Karaarslan,Birol Arifoglu,Ersoy Beser,Sabri Camur 대한전기학회 2018 Journal of Electrical Engineering & Technology Vol.13 No.2
This paper presents a single-phase asymmetric half-bridge cascaded multilevel inverter based series active power filter (SAPF) for harmonic voltage compensation. The effect of level number on performance of the proposed SAPF is examined in terms of total harmonic distortion (THD) and system efficiency. Besides, the relationship between the level number and the number of switching device are compared with the other multilevel inverter topologies used in APF applications. The paper is also aimed to demonstrate the capability of the SAPF for compensating harmonic voltages alone, without using a passive power filter (PPF). To obtain the required output voltage, a new switching algorithm is developed. The proposed SAPF with levels of 7, 15 and 31 is used in both simulation and experimental studies and the harmonic voltages of the load connected to the point of common coupling (PCC) is compensated under two different loading conditions. Furthermore, very high system efficiency values such as 98.74% and 96.84% are measured in the experimental studies and all THD values are brought into compliance with the IEEE-519 Standard. As a result, by increasing the level number of the inverter, lower THD values can be obtained even under high harmonic distortion levels while system efficiency almost remains the same.
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Yaylacı Ayla,Karaarslan Emine Sirin,Hatırlı Hüseyin 대한영상치의학회 2021 Imaging Science in Dentistry Vol.51 No.3
Purpose: The aim of this study was to evaluate the radiopacities of various types of restorative materials with different thicknesses compared with enamel, dentin, and aluminum. Materials and Methods: Four bulk-fill resins, 2 hybrid ceramics, 2 micro-hybrid resin composites, 6 glass ionomer- based materials, 2 zinc phosphate cements, and an amalgam were used in the study. Twelve disk-shaped specimens were prepared from each of 17 restorative materials with thicknesses of 1 mm, 2 mm, and 4 mm (n= 4). All the restorative material specimens with the same thickness, an aluminum (Al) step wedge, and enamel and dentin specimens were positioned on a phosphor storage plate and exposed using a dental X-ray unit. The mean gray values were measured on digital images and converted to equivalent Al thicknesses. Statistical analyses were performed using 2-way analysis of variance and the Bonferroni post hoc test (P<0.05). Results: Radiopacity was significantly affected by both the thickness and the material type (P<0.05). GCP Glass Fill had the lowest radiopacity value for samples of 1 mm thickness, while Vita Enamic had the lowest radiopacity value for 2-mm-thick and 4-mm-thick samples. The materials with the highest radiopacity values after the amalgam were zinc phosphate cements. Conclusion: Significant differences were observed in the radiopacities of restorative materials with different thick- nesses. Radiopacity was affected by both the material type and thickness.
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Ortatepe, Zafer,Karaarslan, Ahmet The Korean Institute of Power Electronics 2020 JOURNAL OF POWER ELECTRONICS Vol.20 No.1
This study presents a pre-calculated duty cycle optimization method based on the genetic algorithm for a non-inverting buck-boost converter (NIBBC). In this method, the duty cycles are calculated via a discrete model estimation of NIBBC. Despite its high computational time requirements, this method can find solutions to problems that other methods cannot overcome due to their lack of linearity, continuity, or other features. This algorithm is developed using the TMS320F28335 digital signal processor, which is a 32-bit floating point processor operating at 150 MHz. The robustness and stability of this method at varying input voltages, loads, and parameters are then analyzed following the IEEE and IEC standards. The experimental results verify the simulation results and highlight the efficiency, power quality, wide output voltage range, and stability of the proposed method.
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Yaylaci, Ayla,Karaarslan, Emine Sirin,Hatırli, Huseyin Korean Academy of Oral and Maxillofacial Radiology 2021 Imaging Science in Dentistry Vol.51 No.-
Purpose: The aim of this study was to evaluate the radiopacities of various types of restorative materials with different thicknesses compared with enamel, dentin, and aluminum. Materials and Methods: Four bulk-fill resins, 2 hybrid ceramics, 2 micro-hybrid resin composites, 6 glass ionomer-based materials, 2 zinc phosphate cements, and an amalgam were used in the study. Twelve disk-shaped specimens were prepared from each of 17 restorative materials with thicknesses of 1 mm, 2 mm, and 4 mm (n=4). All the restorative material specimens with the same thickness, an aluminum (Al) step wedge, and enamel and dentin specimens were positioned on a phosphor storage plate and exposed using a dental X-ray unit. The mean gray values were measured on digital images and converted to equivalent Al thicknesses. Statistical analyses were performed using 2-way analysis of variance and the Bonferroni post hoc test(P<0.05). Results: Radiopacity was significantly affected by both the thickness and the material type (P<0.05). GCP Glass Fill had the lowest radiopacity value for samples of 1 mm thickness, while Vita Enamic had the lowest radiopacity value for 2-mm-thick and 4-mm-thick samples. The materials with the highest radiopacity values after the amalgam were zinc phosphate cements. Conclusion: Significant differences were observed in the radiopacities of restorative materials with different thicknesses. Radiopacity was affected by both the material type and thickness.
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The Mechanical Effect of Rod Contouring on Rod-Screw System Strength in Spine Fixation
Acar, Nihat,Karakasli, Ahmet,Karaarslan, Ahmet A.,Ozcanhan, Mehmet Hilal,Ertem, Fatih,Erduran, Mehmet The Korean Neurosurgical Society 2016 Journal of Korean neurosurgical society Vol.59 No.5
Objective : Rod-screw fixation systems are widely used for spinal instrumentation. Although many biomechanical studies on rod-screw systems have been carried out, but the effects of rod contouring on the construct strength is still not very well defined in the literature. This work examines the mechanical impact of straight, $20^{\circ}$ kyphotic, and $20^{\circ}$ lordotic rod contouring on rod-screw fixation systems, by forming a corpectomy model. Methods : The corpectomy groups were prepared using ultra-high molecular weight polyethylene samples. Non-destructive loads were applied during flexion/extension and torsion testing. Spine-loading conditions were simulated by load subjections of 100 N with a velocity of $5mm\;min^{-1}$, to ensure 8.4-Nm moment. For torsional loading, the corpectomy models were subjected to rotational displacement of $0.5^{\circ}\;s^{-1}$ to an end point of $5.0^{\circ}$, in a torsion testing machine. Results : Under both flexion and extension loading conditions the stiffness values for the lordotic rod-screw system were the highest. Under torsional loading conditions, the lordotic rod-screw system exhibited the highest torsional rigidity. Conclusion : We concluded that the lordotic rod-screw system was the most rigid among the systems tested and the risk of rod and screw failure is much higher in the kyphotic rod-screw systems. Further biomechanical studies should be attempted to compare between different rod kyphotic angles to minimize the kyphotic rod failure rate and to offer a more stable and rigid rod-screw construct models for surgical application in the kyphotic vertebrae.
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