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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Magnetics
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Journal DOI :
The Korean Magnetics Society
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Volume & Issues
Volume 21, Issue 3 - Sep 2016
Volume 21, Issue 2 - Jun 2016
Volume 21, Issue 1 - Mar 2016
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Effect of Proton Irradiation on the Magnetic Properties of Antiferromagnet/ferromagnet Structures
Kim, Dong-Jun ; Park, Jin-Seok ; Ryu, Ho Jin ; Jeong, Jong-Ryul ; Chung, Chang-Kyu ; Park, Byong-Guk ;
Journal of Magnetics, volume 21, issue 2, 2016, Pages 159~163
DOI : 10.4283/JMAG.2016.21.2.159
Antiferromagnet (AFM)/ferromagnet (FM) bilayer structures are widely used in the magnetic devices of sensor and memory applications, as AFM materials can induce unidirectional anisotropy of the FM material via exchange coupling. The strength of the exchange coupling is known to be sensitive to quality of the interface of the AFM/FM bilayers. In this study, we utilize proton irradiation to modify the interface structures and investigate its effect on the magnetic properties of AFM/FM structures, including the exchange bias and magnetic thermoelectric effect. The magnetic properties of IrMn/CoFeB structures with various IrMn thicknesses are characterized after they are exposed to a proton beam of 3 MeV and
. We observe that the magnetic moment is gradually reduced as the amount of the dose is increased. On the other hand, the exchange bias field and thermoelectric voltage are not significantly affected by proton irradiation. This indicates that proton irradiation has more of an influence on the bulk property of the FM CoFeB layer and less of an effect on the IrMn/CoFeB interface.
Effect of Boron Additions on Glass Formation and Magnetic Properties of Fe-Co-Ti-Zr-B Amorphous Ribbons
Kim, Sumin ; Han, Bo Kyeong ; Choi-Yim, Haein ;
Journal of Magnetics, volume 21, issue 2, 2016, Pages 164~167
DOI : 10.4283/JMAG.2016.21.2.164
The effect of the B additions on glass formation and magnetic properties is reported for the
(x = 2, 4, 6 and y = 35, 40) alloy system. The ribbon samples with the width of 2 mm for each composition were prepared by the melt spinning technique; furthermore, their phase information was obtained from X-ray diffraction. Glass formation and magnetic properties were measured using differential scanning calorimetry and vibrating sample magnetometer respectively. The
(x = 2 and y = 40) system has the nanocrystalline phase identified as
, as well as the amorphous phase, whereas all other alloys are fully amorphous. It is associated with the role of B on the glass formation. The widest supercooled liquid region is obtained as 71 K at x = 4 (both y = 35 and 40). The saturation magnetization decreases with the increase of the amount of the B addition, and the highest value is 1.59 T as x = 2 and y = 35 for this alloy system.
Detwinning Monoclinic Phase BiMnO
Dash, Umasankar ; Raveendra, N.V. ; Jung, Chang Uk ;
Journal of Magnetics, volume 21, issue 2, 2016, Pages 168~172
DOI : 10.4283/JMAG.2016.21.2.168
has been a promising candidate as a magnetoelectric multiferroic while there have been many controversial reports on its ferroelectricity. The detailed analysis of its film growth, especially the growth of thin film having monoclinic symmetry has not been reported. We studied the effect of miscut angle, the substrate surface, and film thickness on the symmetry of
thin film. A flat
(110) substrate resulted in a thin film with three domains of
and 1 degree miscut in the
(110) substrate resulted in dominant domain preference in the
thin film. The larger miscut resulted in a nearly perfect detwinned
film with a monoclinic phase. This strong power of domain selection due to the step edge of the substrate was efficient even for the thicker film which showed a rather relaxed growth behavior along the
Rotor Position Detection of CPPM Belt Starter Generator with Trapezoidal Back EMF using Six Hall Sensors
Xu, Jiaqun ; Long, Feng ; Cui, Haotian ;
Journal of Magnetics, volume 21, issue 2, 2016, Pages 173~178
DOI : 10.4283/JMAG.2016.21.2.173
Six-step commutation control widely used in brushless DC (BLDC) motor can be applied to consequent pole permanent magnet (CPPM) belt starter generator (BSG) with trapezoidal back electromotive force (EMF) in the starter state. However, rotor position detection with three Hall sensors in BLDC motor can hardly be employed in CPPM BSG due to asymmetric flux distribution in each pole side of CPPM BSG. This paper presents a low-cost rotor position detection method for CPPM BSG in which six Hall sensors are proposed to be used based on the analysis of flux distribution by 3D FEA. In the method, the six Hall sensors are divided into three groups and two signals in each group are combined through performing logic operations. In addition, offset angle between back EMF and the related Hall signal can be compensated by moving the Hall sensors. Experiments of a 2 kW CPPM BSG prototype have also been performed to verify the proposed method.
Facile Synthesis of Flower-like Superparamagnetic Fe
/BiOCl Nanocomposites as High Effective Magnetic Recyclable Photocatalyst under Visible Light
Wang, Wei ; He, Mingyi ; Zhang, Huan ; Dai, Yatang ;
Journal of Magnetics, volume 21, issue 2, 2016, Pages 179~182
DOI : 10.4283/JMAG.2016.21.2.179
In this paper, 10 nm
nanoparticles were modified on the surface of
flower-like bismuth oxychloride (BiOCl) spheres by a facile co-precipitation method. The results showed that the
nanocomposites exhibited excellent photocatalytic activity and superparamagnetic property (
) under visible light for Rhodamine B (RhB) degradation. Moreover, the
photocatalyst possessed magnetic recyclable property, which could maintain high photocatalytic effective even after 20 cycle times. These characteristic indicates a promising application for wastewater treatment.
Study on Proton Radiation Resistance of 410 Martensitic Stainless Steels under 3 MeV Proton Irradiation
Lee, Jae-Woong ; Surabhi, S. ; Yoon, Soon-Gil ; Ryu, Ho Jin ; Park, Byong-Guk ; Cho, Yeon-Ho ; Jang, Yong-Tae ; Jeong, Jong-Ryul ;
Journal of Magnetics, volume 21, issue 2, 2016, Pages 183~186
DOI : 10.4283/JMAG.2016.21.2.183
In this study, we report on an investigation of proton radiation resistance of 410 martensitic stainless steels under 3 MeV proton with the doses ranging from
at the temperature 623 K. Vibrating sample magnetometer (VSM) and X-ray diffractometer (XRD) were used to study the variation of magnetic properties and structural damages by virtue of proton irradiation, respectively. VSM and XRD analysis revealed that the 410 martensitic stainless steels showed proton radiation resistance up to
. Proton energy degradation and flux attenuations in 410 stainless steels as a function of penetration depth were calculated by using Stopping and Range of Ions in Matter (SRIM) code. It suggested that the 410 stainless steels have the radiation resistance up to
dpa which corresponds to neutron irradiation of
. These results could be used to predict the maintenance period of SUS410 stainless steels in fission power plants.
Analysis of Magnetic Permeability Spectra of Metamaterials Composed of Cut Wire Pairs by Circuit Theory
Lim, Jun-Hee ; Kim, Sung-Soo ;
Journal of Magnetics, volume 21, issue 2, 2016, Pages 187~191
DOI : 10.4283/JMAG.2016.21.2.187
Retrieving the equivalent electromagnetic parameters (permittivity and permeability) plays an important role in the research and application of metamaterials. Frequency dispersion of magnetic permeability has been theoretically predicted in a metamaterial composed of cut wire pairs (CWP) separated by dielectric substrate on the basis of circuit theory. Magnetic resonance resulting from antiparallel currents between the CWP is observed at the frequency of minimum reflection loss (corresponding to absorption peak) and effective resonator size can be determined. Having calculated the circuit parameters (inductance L, capacitance C) and resonance frequency from CWP dimension, the frequency dispersion of permeability of Lorentz like magnetic response can be predicted. The simulated resonance frequency and permeability spectra can be explained well on the basis of the circuit theory of an RLC resonator.
Effect of Ca and Al Additions on the Magnetic Properties of Nanocrytalline Fe-Si-B-Nb-Cu Alloy Powder Cores
Moon, Sun Gyu ; Kim, Ji Seung ; Sohn, Keun Yong ; Park, Won-Wook ;
Journal of Magnetics, volume 21, issue 2, 2016, Pages 192~196
DOI : 10.4283/JMAG.2016.21.2.192
The Fe-Si-B-Nb-Cu alloys containing Ca and Al were rapidly solidified to thin ribbons by melt-spinning. The ribbons were ball-milled to make powders, and then mixed with 1 wt.% water glass and 1.5 wt.% lubricant. The mixed powders were burn-off, and then compacted to form toroidal-shaped cores, which were heat treated to crystallize the nano-grain structure and to remove residual stress of material. The characteristics of the powder cores were analyzed using a differential scanning calorimetry (DSC) and a B-H meter. The microstructures were observed using transmission electron microscope (TEM). The optimized soft magnetic properties (
) of the powder cores were obtained from the Ca and Al containing alloys after annealing at
for 1 h. The core loss of Fe-Si-B-Nb-Cu-based powder cores was reduced by the addition of Ca element, and the initial permeability increased due to the addition of Al element.
Efficient Re-degaussing Technique for a Naval Ship Undergoing a Breakdown in Degaussing Coils
Kim, Dong-Wook ; Lee, Sang-Kyun ; Kang, Byungsu ; Cho, Jeonghun ; Lee, WooSeok ; Yang, Chang-Seob ; Chung, Hyun-Ju ; Kim, Dong-Hun ;
Journal of Magnetics, volume 21, issue 2, 2016, Pages 197~203
DOI : 10.4283/JMAG.2016.21.2.197
A naval ship equipped with a degaussing system may undergo a breakdown in degaussing coils at sea. In the case, underwater magnetic field around the ship abruptly grows up and it can make the ship be easily exposed to fatal hazards such as magnetic mines or torpedoes. This paper proposes an efficient and practical re-degaussing technique for a ship where a part of degaussing coils is out of order. To achieve this, an analytical design sensitivity formula and approximated degaussing coil field are exploited, and then new optimum currents of available coils are reassessed. To validate the proposed method, a muck-up ship equipped with 14 degaussing coils is tested in scale-down magnetic treatment facilities under three faulty coil conditions.
A Non-contact Detection Method for Smelting in Submerged Arc Furnace based on Magnetic Field Radiation
Liu, WeiLing ; Chang, XiaoMing ;
Journal of Magnetics, volume 21, issue 2, 2016, Pages 204~208
DOI : 10.4283/JMAG.2016.21.2.204
This paper demonstrates the key parameter detection for smelting of submerged arc furnace (SAF) based on magnetic field radiation. A magnetic field radiation model for the inner structure of SAF is established based on relative theory of electromagnetic field. A simple equipment of 3D magnetic field detection system is developed by theoretical derivation and simulation. The experiments are carried out under the environment of industrial field and AC magnetic field generated by electrode currents and molten currents in the furnace is reflected outside of the furnace. The experimental results show that the key parameters of smelting including the position of electrode tip, the length of electric arc, and the liquid level of molten bath can be achieved. The computed tomography for SAF can be realized by the detection for smelting.
The Magnetic Properties of Electrical Steel for Rotating Machine according to the Specimen
Choi, Yun-Yong ; Chin, Jun-Woo ; Hong, Jung-Pyo ;
Journal of Magnetics, volume 21, issue 2, 2016, Pages 209~214
DOI : 10.4283/JMAG.2016.21.2.209
This paper analyzes the magnetic property according to the machined shape of steel material with non-oriented silicon steel (50PN470/50A470), that is most commonly used in the design of electrical equipment. Toward this end, specimens were produced and divided into Bar-Specimen (Epstein Frame Tester) and Ring-Specimen (Toroidal Ring Tester). The characteristics of the electrical Silicon steel were measured using the instruments solely dedicated to measuring each specimen. The core loss of the Bar-Specimen, which is commonly used, was found to be less than that of the Ring-Specimen. This is a very important design factor in achieving the objectives of improving the product efficiency and predicting the performance of electrical equipment. It serves as a critical point of view in order to reduce the error between design value and product value. A comparative analysis was conducted regarding various characteristics (Hysteresis, B-H characteristic, Iron loss, Minor loop, Coercive force, Residual magnetic flux density, etc.) of the electrical silicon steel considered in the design of the electrical equipment according to the specimen.
Electromagnetic Forming Process Analysis Based on Coupled Simulations of Electromagnetic Analysis and Structural Analysis
Lee, Man Gi ; Lee, Seung Hwan ; Kim, Sunwoo ; Kim, Jin Ho ;
Journal of Magnetics, volume 21, issue 2, 2016, Pages 215~221
DOI : 10.4283/JMAG.2016.21.2.215
We conducted a phased electromagnetic forming process analysis (EFPA) over time through a coupling of electromagnetic analysis and structural analysis. The analysis is conducted through a direct linkage between electromagnetic analysis and structural analysis. The analysis process is repeated until the electric current is completely discharged by a formed coil. We calculate the forming force that affects the workpiece using MAXWELL, a commercial electromagnetic finite element analysis program. Then, we simulate plastic behavior by using the calculated forming force data as the forming force input to ANSYS, a commercial structure finite element analysis program. We calculate the forming force data by using the model shape in MAXWELL, a commercial electromagnetic finite element analysis program. We repeat the process until the current is fully discharged by the formed coil. Our results can be used to reduce the error in data transformation with a reduced number of data transformations, because the proposed approach directly links the electromagnetic analysis and the structural analysis after removing the step of the numerical analysis of a graph describing the forming force, unlike the existing electromagnetic forming process. Second, it is possible to simulate a more realistic forming force by keeping a certain distance between nodes using the re-mesh function during the repeated analysis until the current is completely discharged by the formed coil, based on the MAXWELL results. We compare and review the results of the EFPA using the peak value of the forming force that acts on the workpiece (which is the existing analysis method), and the proposed phased EFPA over time approach.
Correlation between Coil Configurations and Discharge Characteristics of a Magnetized Inductively Coupled Plasma
Cheong, Hee-Woon ;
Journal of Magnetics, volume 21, issue 2, 2016, Pages 222~228
DOI : 10.4283/JMAG.2016.21.2.222
Correlation between coil configurations and the discharge characteristics such as plasma density and the electron temperature in a newly designed magnetized inductively coupled plasma (M-ICP) etcher were investigated. Radial and axial magnetic flux density distributions as well as the magnetic flux density on the center of the substrate holder were controllable by placing multiple circular coils around the etcher. The plasma density increased up to 60.7% by arranging coils (or optimizing magnetic flux density distributions inside the etcher) properly although the magnetic flux density on the center of the substrate holder was fixed at 7 Gauss.
Study on the Preparation Process and Properties of Magnetorheological Fluid Treated by Compounding Surfactants
Wu, Xiangfan ; Xiao, Xingming ; Tian, Zuzhi ; Chen, Fei ;
Journal of Magnetics, volume 21, issue 2, 2016, Pages 229~234
DOI : 10.4283/JMAG.2016.21.2.229
Aiming to prepare high performance magnetorheological fluid, firstly, oleic acid and sodium dodecyl benzene sulfonate are chosen as surfactants. And then, the mechanical stirring process including stirring time, stirring temperature and stirring speed are optimized by measuring sedimentation ratio and zero-field viscosity. Finally, the properties of prepared magnetorheological fluid are elaborated. The results indicate that the compounding of oleic acid and sodium dodecyl benzene sulfonate can improve the properties of magnetorheological fluid distinctively, and the optimistic compounding content is 4g:4g or 5g:5g. The surfactants adding orders and the second stirring time have little effect on the properties of magnetorheological fluid, while obviously of the first stirring time, temperature and speed. Moreover, the sedimentation ratio of prepared magnetorheological fluid is less than 5.2% in two weeks, the zero-field viscosity is smaller than
, and the maximum yield stress is higher than 50 kPa.
Synthesis, Structure and Magnetization Behaviors of MnBi/Fe
B Nanocomposite alloy
Yang, Y. ; Wu, Q. ; Hu, Y.C. ; Zhang, P.Y. ; Ge, H.L. ;
Journal of Magnetics, volume 21, issue 2, 2016, Pages 235~238
DOI : 10.4283/JMAG.2016.21.2.235
Microstructure and magnetization behaviors of
nanocomposite alloy have been investigated. It was found that the coercivity increased firstly and then decreased, and saturation magnetization decreased with the additon of MnBi alloy. The addition of 40 wt.% MnBi powder enhanced the coercivity from 192.8 kA/m to 311.2 kA/m. The
and D(H)-H plots suggested the occurrence of a stronger exchange-coupling occurring between the hard and soft magnetic phase for this sample. The dependence of coercivity with temperature was discussed in 40 wt.%
/ 60 wt.%
alloy powder, and a positive temperature coefficient was founded from 298 K to 350 K.
A Rotating Flux Pump Employing a Magnetic Circuit and a Stabilized Coated Conductor HTS Stator
Jiang, Z. ; Bumby, C.W. ; Badcock, R.A. ; Long, N.J. ; Sung, H.J. ; Park, M. ;
Journal of Magnetics, volume 21, issue 2, 2016, Pages 239~243
DOI : 10.4283/JMAG.2016.21.2.239
High temperature superconductor (HTS) magnet systems usually employ metal current leads which bridge between the cryogenic environment and room temperature. Such current leads are the dominant heat load for these magnet systems due to a combination of electrical resistance and heat conduction. HTS flux pumps enable large currents to be injected into a HTS magnet circuit without this heat load. We present results from an axial-type HTS mechanically rotating flux pump which employs a ferromagnetic circuit and a Cu-stabilized coated conductor (CC) HTS stator. We show the device can be described by a simple circuit model which was previously used to describe barrel-type flux pumps, where the model comprises an internal resistance due to dynamic resistance and a DC voltage source. Unlike previously reported devices, we show the internal resistance and DC voltage in the flux pump are not exactly proportional to frequency, and we ascribe this to the presence of eddy currents. We also show that this axial-type flux pump has superior current injection capability over barrel-type flux pumps which do not incorporate a magnetic circuit.
Effect of Particle Characteristics and Temperature on Shear Yield Stress of Magnetorheological Fluid
Wu, Xiangfan ; Xiao, Xingming ; Tian, Zuzhi ; Chen, Fei ; Jian, Wang ;
Journal of Magnetics, volume 21, issue 2, 2016, Pages 244~248
DOI : 10.4283/JMAG.2016.21.2.244
Aiming to improve the shear yield stress of magnetorheological fluid, magnetorheological fluids with different particle characteristics are prepared, and the influence rules of particle mass fraction, particle size, nanoparticles content and application temperature on shear yield stress are investigated. Experimental results indicate that shear yield stress increases approximate linearly with the enhancement of particle mass fraction. Particle size and the nanoparticles within 10% mass fraction can improve the shear yield stress effectively. When the application temperature is higher than
, the shear yield stress decreases rapidly because of thermal expansion and thermal magnetization effect.
Demagnetization Diagnosis of Permanent Magnet Synchronous Motor Using Frequency Analysis at Standstill Condition
Yoo, Jin-Hyung ; Jung, Tae-Uk ;
Journal of Magnetics, volume 21, issue 2, 2016, Pages 249~254
DOI : 10.4283/JMAG.2016.21.2.249
Recently, electric vehicles have got significant attention because it is more eco-friendly and efficient than internal combustion engine vehicles. Instead of an internal combustion engine, the electric vehicle has a motor for propulsion. The permanent magnet synchronous motor which has permanent magnet instead of field winding in the rotor has especially higher efficiency and power density than other types of motor. When the irreversible demagnetization is occurred, drivers are exposed to high risk of accident by the fault operation of motor. Therefore, the irreversible demagnetization of permanent magnet should be detected to reduce the risk of accident. In this study, the demagnetization diagnosis method based on the result of locked rotor test is proposed. Based on short measurement time, the proposed diagnosis method aims to detect the demagnetization fault when an electric vehicle is at a complete standstill. The proposed method is verified through the finite element analysis.
Occupational Exposure to Steady Magnetic Fields and its Effect on Workers Blood Indices at an Electrolysis Unit
Ravandi, Mohammad Reza Ghotbi ; Mardi, Hossein ; Khanjani, Narges ; Barkhordari, Abolfazl ;
Journal of Magnetics, volume 21, issue 2, 2016, Pages 255~260
DOI : 10.4283/JMAG.2016.21.2.255
The health effects of environmental and occupational exposure to steady magnetic fields is a matter of concern. The aim of this study was to evaluate the hematologic effects of exposure to steady magnetic fields at the electrolysis unit of a Copper complex. The population under study was the workers of the electrolysis unit of the copper refinery. The average steady magnetic field in the exposure group was 2.5 mT. The blood indices of workers exposure to steady magnetic fields after adjusting for confounders showed decreased white blood cells (except neutrophils) and increase in the number and volume of platelets. Red blood cells did not show any significant difference. Exposure to steady magnetic fields even in proposed safe limits may have hematologic effects on humans. There is a necessity for more research about the safe doses of exposure to magnetic fields.
Surface Tension of Magneto-Rheological Fluids
Rahimi, Shai ; Weihs, Daniel ;
Journal of Magnetics, volume 21, issue 2, 2016, Pages 261~265
DOI : 10.4283/JMAG.2016.21.2.261
Surface tension is a major factor in the thermodynamics as well as fluid properties of Magneto-Rheological Fluids (MRF). We measured the surface tension of an MRF using two different methods. A wettability characterization based on contact angles measurements for the fluid interacting with two different surfaces was conducted. A hydrocarbon based commercial MRF with more than 80% solid weight, placed on quartz and poly-tetra-fluoroethylene (PTFE) surfaces was used. We measured the fluids' surface tension value by means of contact angles measurements and by the falling drop method.
Arm Cortex S3C2440 Microcontroller Application for Transcranial Magnetic Stimulation's Pulse Forming on Bax Reactive Cells and Cell Death in Ischemia Induced Rats
Tac, Han-Ho ; Kim, Whi-Young ;
Journal of Magnetics, volume 21, issue 2, 2016, Pages 266~272
DOI : 10.4283/JMAG.2016.21.2.266
Transcranial magnetic stimulation devices has been used mainly for diagnostic purposes by measuring the functions of the nervous system rather than for treatment purposes, and has a problem of considerable energy fluctuations per repeated pulse. The majority of strokes are caused by ischemia and result in brain tissue damage, leading to problems of the central nervous system including hemiparesis, dysfunction of language and consciousness, and dysfunction of perception. Control is difficult and the size is large due to the difficulty of digitalizing the energy stored in a capacitor, and there are many heavy devices. In addition, there are many constraints when it is used for a range of purposes such as head and neck diagnosis, treatment and rehabilitation of nerve palsy, muscle strengthening, treatment of urinary incontinence etc. Output stabilization and minimization of the energy variation rate are required as the level of the transcranial magnetic stimulation device is dramatically improved and the demand for therapeutic purposes increases. This study developed a compact, low cost transcranial magnetic stimulation device with minimal energy variation of a high repeated pulse and output stabilization using a real time capacitor charge discharge voltage. Ischemia was induced in male SD rats by closing off the common carotid artery for 5 minutes, after which the blood was re-perfused. In the cerebrum, the number of PARP reactive cells after 24 hours significantly decreased (p < 0.05) in the TMS group compared to the GI group. As a result, TMS showed the greatest effect on necrosis-related PARP immuno-reactive cells 24 hours after ischemia, indicating necrosis inhibition, blocking of neural cell death, and protection of neural cells.
Bionic Study of Variable Viscosity on MHD Peristaltic Flow of Pseudoplastic Fluid in an Asymmetric Channel
Khan, Ambreen A. ; Muhammad, Saima ; Ellahi, R. ; Zia, Q.M. Zaigham ;
Journal of Magnetics, volume 21, issue 2, 2016, Pages 273~280
DOI : 10.4283/JMAG.2016.21.2.273
In this paper, the peristaltic flow of Psedoplastic fluid with variable viscosity in an asymmetric channel is examined. The bionic effects by means of magnetohydrodynamics (MHD) are taken into account. The assumptions of long wave length and low Reynolds number are taken into account. The basic equations governing the flow are first reduced to a set of ordinary differential equation by using appropriate transformation for variables and then solve by using perturbation method. The effect of physical parameters on the pressure rise, velocity and pressure gradient are illustrated graphically. The trapping phenomenon is analyzed through stream lines. A suitable comparison has also been made as a limiting case of the considered problem.
Comparison Study of Image Performance with Contrast Agent Contents for Brain Magnetic Resonance Imaging
Lee, Youngjin ; Choi, Min Hyeok ; Goh, Hee Jin ; Han, Dong-Kyoon ;
Journal of Magnetics, volume 21, issue 2, 2016, Pages 281~285
DOI : 10.4283/JMAG.2016.21.2.281
The purpose of study was to evaluate SNR and CNR with different contrast agent contents (1.0 mmol/mL gadobutrol and 0.5 mmol/mL gadoterate meglumine) for spin echo (SE) and 3-dimension contrast-enhanced fast field echo (3D CE-FFE) pulse sequences. In this study, we compared the SNR and the CNR between 0.5 mmol/mL gadoterate meglumine and 1.0 mmol/mL gadobutrol according to the concentration of contrast agent in brain MRI. When we compared between SE and 3D CE-FFE pulse sequences, the higher SNR and CNR using 3D CE-FFE pulse sequence can be acquire regardless of contrast agent contents. Also, a statistically significant difference was found for SNR and CNR between all protocols. In conclusion, our results demonstrated that the SNR and CNR have not risen proportionately with contrast agent contents. We hope that these results presented in this paper will contribute to decide contrast agent contents for brain MRI.
Differential Absorption Analysis of Nonmagnetic Material in the Phantom using Dual CT
Kim, Ki-Youl ; Lee, Hae-Kag ; Cho, Jae-Hwan ;
Journal of Magnetics, volume 21, issue 2, 2016, Pages 286~292
DOI : 10.4283/JMAG.2016.21.2.286
This study evaluates the change of computer tomography (CT) number in the case of the metal artifact reduction (MAR) algorithm, using the phantom. The images were obtained from dual CT using a gammex 467 tissue characterization phantom, which is similar to human tissues. The test method was performed by dividing pre and post MAR algorithm and measured CT values of nonmagnetic materials within the phantom. In addition, the changes of CT values for each material were compared and analyzed after measuring CT values up to 140 keV, using the spectral HU curve followed by CT scan. As a result, in the cases of N rod (trabecular bone) and E rod (trabecular bone), the CT numbers decreased as keV increasing but were constant above 90 keV. In the cases of I rod (dense bone) and K rod (dense bone), the CT numbers also decreased as keV increased but were uniform above 90 keV. The CT numbers from 40 keV to 140 keV were consistent in the cases of J rod (liver), D rod (liver), L rod (muscle), and F rod (muscle). For A rod (adipose), G rod (adipose), B rod (breast) and O rod (breast), the CT numbers increased as keV increased but were constant after 90 keV. The CT numbers from 40 keV to 140 keV were consistent in the cases of C rod (lung (exhale)), P rod (lung (exhale)), M rod (lung (inhale)) and H rod (lung (exhale)). Conclusively, because dual CT exhibits no changes in image quality and is able to analyze nonmagnetic materials by measuring the CT values of various materials, it will be used in the future as a useful tool for the diagnosis of lesions.
Chest-wall Surface Dose During Post-mastectomy Radiation Therapy, with and without Nonmagnetic Bolus: A Phantom Study
Choi, Cheon Woong ; Hong, Joo Wan ; Park, Cheol Soo ; Ahn, Jae Ouk ;
Journal of Magnetics, volume 21, issue 2, 2016, Pages 293~297
DOI : 10.4283/JMAG.2016.21.2.293
For mastectomy patients, sufficient doses of radiation should be delivered to the surface of the chest wall to prevent recurrence. A bolus is used to increase the surface dose on the chest wall, whereby the surface dose is confirmed with the use of a virtual bolus during the computerized treatment-planning process. The purpose of this study is an examination of the difference between the dose of the computerized treatment plan and the dose that is measured on the bolus. Part of the left breast of an Anderson Rando phantom was removed, followed by the attainment of computed tomography (CT) images that were used as the basis for computerized treatment plans that were established with no bolus, a 3 mm-thick bolus, a 5 mm-thick bolus, and a 10 mm-thick bolus. For the computerized treatment plan, a prescribed dose regimen was dispensed daily and planning target volume (PTV) coverage was applied according to the RTOG 1304 guidelines. Using each of the established computerized treatment plans, chest-wall doses of 5 points were measured; this chest-wall dose was used as the standard for the analysis of this study, while the level of significance was set at P < 0.05. The measurement of the chest-wall dose with no bolus is 1.6 % to 10.3 % higher, and the differences of the minimum average and the maximum average of the five measurement points are -13.8 and -1.9, respectively (P < 0.05); however, when the bolus was used, the dosage was measured as 3.7 % to 9.2 % lower, and the differences of the minimum average and the maximum average are 7.4 and 9.0, -1.2 and 17.4, and 8.1 and 19.8 for 3 mm, 5 mm, and 10 mm, respectively (P < 0.05). As the thickness of the bolus is increased, the differences of the average surface dose are further increased. There are a variety of factors that affect the surface dose on the chest wall during post-mastectomy radiation therapy, for which verification is required; in particular, a consideration of the appropriate thickness and the number of uses when a bolus is used, and which has the greatest effect on the surface dose on the chest wall, is considered necessary.
Development of a Femur Neck Bone Mineral Density Measuring Device for Accurate Examination
Han, Man-Seok ; Seo, Sun-youl ; Kim, Yong-Kyun ; Jeon, Min-Cheol ; Lee, Hyun-kuk ; Yoo, Se-Jong ;
Journal of Magnetics, volume 21, issue 2, 2016, Pages 298~302
DOI : 10.4283/JMAG.2016.21.2.298
In bone density examinations, a change in the measured BMD occurs owing to the differences between the measured areas. To address this problem, we aimed to develop a new auxiliary device that could be rotated by
by fixing the ankle to the distal femur neck. Dual energy X-ray absorptiometry (DXA) of BMD examinations were performed once a year, but 10 patients were examined over three sessions to analyze the area for measuring the femur neck BMD. The goal of this test was to determine the device's reliability, and the results were expressed in terms of the standard deviation of measurements. After performing bone density measurements using the new auxiliary device on 10 normal patients, with three measurements for each patient, the obtained standard deviation was 0.03. The standard deviation of the measured BMD was 0.19 when using the currently existing auxiliary device, while the standard deviation of the measured BMD was 0.03 when using the new auxiliary device. By using the new auxiliary device, the standard deviation could be reduced by ~80%. Accurate rotation of the femur neck was possible in all examinations, and the standard deviation of BMD measurements could be reduced by up to 80% compared with the measurements performed using the currently existing auxiliary device. We hope that this advantageous new design can be used as a standard auxiliary device for measuring the femur neck BMD.