• Journal of the Korean Magnetics Society
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• v.18 no.1
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• pp.28-31
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• 2008

We studied the effect of easy magnetization axis orientation with respect to the strip direction by measuring the magnetoresistance(MR), the magneto-optic Kerr effect(MOKE), and real-time domain evolution. The five strips were patterned on a single chip with the easy axis orientation of each strip relative to the longitudinal direction by around $0^{\circ}$, $18^{\circ}$, $36^{\circ}$, $54^{\circ}$ and $72^{\circ}$, respectively. The overall shape of field dependent MR was mostly governed by the anisotropy magnetoresistnace. The relative change of the longitudinal MR was significantly increased with increasing angle between the easy axis and strip direction, whereas, the transverse MR variation rate was decreased with increasing angle. Several MR steps were observed during the magnetization reversal, and the simultaneous measurement of the MOKE and the domain images identified that the MR steps were associated with evolution of the oppositely directed magnetic domain.

• Journal of the Korean Society of Clothing and Textiles
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• v.45 no.5
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• pp.907-921
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• 2021

This study aims to predict causal relationships between experience economy, perceived flow, and continuous use intention in the mixed reality (MR) environment. A virtual fitting mirror with two modes (i.e., avatar and self-image) was selected for this study. A total of 200 samples was obtained in two sample frames: virtual fitting users in avatar mode (group 1, n = 119) and self-image mode (group 2, n = 81). The results showed that the experience economy consists of entertainment, education, esthetic, and escapism. The entertainment and esthetic experiences had positive effects on perceived flow, leading to continuous use intentions. For avatar mode, the entertainment and esthetic experiences had positive effects on continuous use intentions through the mediating effect of flow; and the education experience had a positive effect on the continuous intentions to use the MR technology. For self-image mode, the flow mediated the effect of entertainment on continuous use intentions, whereas education and escapism directly affected the intention to use the MR technology. The paper also discusses the theoretical and managerial implications of using MR technologies in fashion retailing.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.369-374
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• 2007

This paper presents yaw vibration control performances of railway vehicle featuring controllable magnetorheological damper. A cylindrical type of MR damper is devised and its damping force is evaluated by considering fluid resistance and MR effect. Design parameters are determined to achieve desired damping force level. The MR damper model is then incorporated with the governing equations of motion of the railway vehicle which includes vehicle body, bogie and wheel-set. Subsequently, computer simulation of vibration control via proportional-integral-derivative (PID) controller is performed using Matlab. Various control performances are demonstrated under external excitation by creep force between wheel and rail.

• Tribology and Lubricants
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• v.29 no.1
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• pp.39-45
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• 2013

Magnetorheological (MR) fluid belongs to the group of smart materials. In MR fluid, iron particles in base oil form chains in the direction of the applied magnetic field, thus resulting in a variation in the stiffness and damping characteristics of the fluid. Research is being carried out on controlling the stiffness and damping characteristics as well as the tribological characteristics of the MR fluid. In this study, the friction characteristics of MR fluid have been evaluated using three types of materials and magnetic fields of different strengths. The coefficients of friction of the three types of MR fluid are measured, and the relationship between the coefficient of friction and the strength of the applied magnetic field is obtained.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.5
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• pp.524-532
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• 2008

This paper presents yaw vibration control performances of railway vehicle featuring controllable magnetorheological damper. A cylindrical type of MR damper is devised and its damping force is evaluated by considering fluid resistance and MR effect. Design parameters are determined to achieve desired damping force level. The MR damper model is then incorporated with the governing equations of motion of the railway vehicle which includes vehicle body, bogie and wheel-set. Subsequently, computer simulation of vibration control via proportional-integral-derivative(PID) controller is performed using Matlab. Various control performances are demonstrated under external excitation by creep force between wheel and rail.

• Journal of Korean Association for Spatial Structures
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• v.12 no.4
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• pp.99-108
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• 2012

In recently, sky-bridge are often applied to high-rised adjacent buildings for pedestrian bridge. the seisnic response control of adjacent buildings have been studied and magneto-rheological(MR) fluid dampers have been applied to seismic response control. In this study, vibration control effect of the MR damper connected adjacent buildings has been investigated. Adjacent building structures with different natural frequencies were used as example structures. Two typed of control methods, displacement based or velocity based, are applied to determinate control force of MR damper. In this numerical analysis, it has been shown that displacement-based control algorithm is more effective than velocity-based control algorithm for seismic response control of adjacent buildings. And, when displacement-based control method is applied to control of adjacent buildings, the control of building occurred large displacement is more efficient in reducing the seismic response.

• 유체기계공업학회:학술대회논문집
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• 1998.02a
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• pp.220-227
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• 1998

This paper evaluate the performance of a Magneto-Rheological (MR) fluid mount. The mount incorporates MR fluid in a conventional fluid mount to open and closed the inertia track between the fluid chambers of the mount. It is shown that such switching of the inertia track improves the mount's isolation effect, by eliminating the large transmissibility peak that commonly exists at frequencies higher than the notch frequency for conventional fluid mounts. The switching frequencies of the MR mount is evaluated, based on the parameters of the mount. A simple control scheme for switching the mount between the open and closed states is proposed, and the performance of the controlled mount is compared with conventional mounts. A sensitivity analysis is conducted to evaluate the effect of parameter errors in estimating the switching frequencies and mount performance. The results show that the switching frequencies can be accurately determined from mount parameters that are easily measured or estimated.

• Journal of radiological science and technology
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• v.41 no.2
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• pp.103-107
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• 2018

In MR, the iodine CT contrast medium reduces the T1 and T2 relaxation times of the substance, resulting in a change in signal intensity. This study aimed to measure the relaxation rate of MR contrast medium with or without diluting CT contrast medium and analyzed the effect of CT contrast medium. Undiluted Gadoteridol solution was diluted with saline to prepare MR contrast medium phantoms with various levels of Gadoteridol concentrations. Moreover, undiluted Iomeprol was mixed with the prepared MR contrast medium phantoms at 1:1 ratio to make MR contrast medium phantoms with containing CT contrast medium for the experiment. T1 and T2 mappings were conducted to quantitatively evaluate the relaxation time and relaxation rate of these phantoms. The results showed that the T1 and T2 relaxation time and relaxation rate of MR contrast medium diluted with CT contrast medium were significantly (p<0.05) shorter than those of MR contrast medium not diluted with CT contrast medium. The results of this study imply that, when MR contrast medium shall be used after injecting CT contrast medium, CT contrast medium should be discharged enough. Moreover, it would be desirable to conduct CT test after taking MRI test in order to reduce the effects of CT contrast medium on MR contrast medium.

• Elastomers and Composites
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• v.53 no.2
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• pp.67-74
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• 2018

Magneto-rheological elastomers (MREs) are smart materials in which the inherent stiffness and damping properties can be changed by the influence of an external magnetic field. The magneto-rheological (MR) effect depends on the orientation characteristics of the dispersed magneto-responsible particles (MRPs) in the matrix. In this study, natural rubber (NR) and ethylene propylene diene rubber (EPDM) were blended and used as a matrix of an MRE. EPDM was pre-cured before blending with NR. The Mooney viscosity, curing characteristics, and mechanical properties were analyzed with various pre-curing conditions of EPDM and the NR/EPDM blend. The results show that excellent mechanical properties of the NR/EPDM blend-based MRE were obtained when the pre-curing time of EPDM was 60 min. The aging property of the NR-based MRE was improved by the introduction of pre-cured EPDM. Also, the anisotropic MRE showed a higher MR effect than that of the isotropic MRE.

• Investigative Magnetic Resonance Imaging
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• v.7 no.1
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• pp.31-38
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• 2003

Purpose : To analyze the serial changes of proton magnetic resonance (MR) spectra in the abscess and to determine the effect of the antibiotic treatment on the metabolite patterns. Materials and Methods : MR imaging and MR spectroscopy of an experimentally induced abscess were performed sequentially for four weeks at interval of one week in both the control group (n=5) and the antibiotic treatment group (n=5). On MR imaging, the shape and the size of the abscess were analyzed. On MR spectroscopy, the resonance peaks of metabolites were assigned on the basis of reported peaks in the literature. The metabolite ratios measured by using N-acetyl alanine as an external reference and by using lipid as an internal reference were compared in both the control and treatment g roups. Results : The abscesses were seen as cystic masses on MR imaging. On MR spectroscopy, the variable peaks of acetate, succinate and various amino acids, which are the metabolites of infection, were identified in the control and antibiotic treatment groups. The most frequent peak was that of acetate at 1.92ppm (70%). Both the peak ratios of acetate to lipid and acetate to external reference tended to decrease in the treatment group while the ratios did not change significantly in the control group. Conclusion : MR spectroscopy is useful not only for the diagnosis of abscess but also for monitoring the evolution of the abscess by using the acetate peak.