• Health Policy and Management
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• v.31 no.3
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• pp.261-271
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• 2021

Background: In 2018, the government increased the fee for the magnetic resonance imaging (MRI) image deciphering services of the external hospital to discourage the redundant MRI scan and to induce appropriate use of the MRI services. It is important to evaluate the effect of the policy to provide the basis for establishing other MRI-related policies. Methods: The healthcare data of the patients who had brain MRI scans were organized by episode and analyzed using the panel study in order to find out the effect of the MRI-related policy on the substitution effect and the medical expenses. Results: As a result of the increase in the fee of deciphering the MRI image, there has been an uplift in deciphering the MRI scan of the external hospital. It implies that more hospitals chose to use the MRI scan taken by other clinics or hospitals, rather than the MRI scan taken at their own facilities. Conclusion: The research results imply that a policy that facilitates the exchange of the medical image data between the hospitals is needed in order to establish an efficient management system of the healthcare resources. Such improvement is expected to reduce the social cost and contribute to the stability in the finance of national health insurance.

• Investigative Magnetic Resonance Imaging
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• v.24 no.2
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• pp.67-75
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• 2020

When a patient takes an MRI scan, the patient has a risk of unexpected injuries due to the intensive electromagnetic (EM) field. Among the injuries, the tissue heating by the time-varying EM field is one of the main issues. Since an implanted artificial structure with a conductive material aggravates the heating effect, lots of studies have been conducted to investigate the effect around the implants. In this review article, a mechanism of RF heating around the implants and related studies are comprehensively investigated.

• Proceedings of the KSR Conference
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• 2000.11a
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• pp.527-534
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• 2000

Characteristics of local vibration modes of a corrugated panel are investigated by finite element analysis and modal testing. Structural modification model in the corrugation is proposed to increase the resonance frequency. This model decreases the fall by the local resonance in the transmission loss of the corrugated pallet and improves sound insulation performance. Damping effect of tile foam filled ill tile core cavity is also estimated by experiment The results of tile study offer useful information how to predict the severe local resonances in corrugations and how to prevent their undesirable effect ell the sound insulation and the vibration transmission.

• Journal of Sensor Science and Technology
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• v.29 no.1
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• pp.33-39
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• 2020

Typically, photoacoustic images are obtained in water or gelatin because the impedance of these mediums is similar to that of the human body. However, these acoustic mediums can have an additional mass effect that changes the resonance frequency of the transducer. The acoustic radiation impedance in air is negligible because it is very small compared to that of the transducer. However, the high acoustic impedance of mediums such as the human body and water is quite large compared to that of air, making it difficult to ignore. Specifically, in a case where the equivalent mass is very small, such as with a micro-machined ultrasound transducer, the additional mass effects of the acoustic medium should be considered for an accurate resonance frequency design. In this study, a piezoelectric micro-machined ultrasonic transducer (pMUT) was designed to have a resonance frequency of 10 MHz in the acoustic medium of water, which has similar impedance as the human body. At that time, the resonance frequency of the pMUT in air was calculated at 15.2 MHz. When measuring the center displacement of the manufactured pMUT using a laser vibrometer, the resonance frequencies were measured as 14.3-15.1 MHz, which is consistent with the finite element method (FEM) simulation results. Finally, photoacoustic images of human hair samples were successfully obtained using the fabricated pMUT.

• Investigative Magnetic Resonance Imaging
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• v.4 no.2
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• pp.120-127
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• 2000

Adaptive template filtering has been proposed recently for enhancement of signal-to-noise ratio without loss of resolution. In the adaptive template filtering, an optimal template among multiple templates is selected, then linear least square error filtering based on the template is applied in vowel by vowel basis. In some magnetic resonance imaging, where the distribution of gray level has relatively small dynamic range, e.g., $T_1$ imaging, however, artificial stair-like artifact is observed at near edges. This is partially due to the edge enhancement effect in such yokels that contain multiple compounds at the boundaries of tissues. The gray levels of these yokels become similar gray levels of near dominant vowels that contain single compound by the adaptive filtering, which enlarges edge discontinuities. In this paper, we propose a technique to eliminate such artifact by identifying those yokels that contain multiple compounds and assigning the largest template for them. Filtered images with the proposed technique show substantial visual enhancement at the edges without degradation of peak signal-to-noise ratio compared to the original adaptive template filtering for both magnetic resonance images and phantom images.

• Journal of the Korean Ceramic Society
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• v.32 no.2
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• pp.163-170
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• 1995

Sample size effect on ferromagnetic resonance (FMR) in polycrystalline MgFe2O4 has been investigated. The signal intensity (SI), resonance field (Hres) and line width (ΔH) were found to increase proportionally to r3 with the increase of sample radius. The r3-depencence of SI means the complete penetration of rf-field into the sample, and the broadening of ΔH due to the sample size appears to be closely related to the amount of scattering sources like pores. Meanwhile, the values of Hres (0) and ΔH (0) obtained by extrapolating the data of Hres (r) and ΔH (r) measured at several sizes to r=0, were in good agreement with those calculated using the Schlomann's equations for internal field and ΔH, respectively. This result indicates that the discrepancy between the measured FMR parameters and those calculated by Schlomann's equation could be ascribed to the effect of sample size. Thus it is suggested that the size effect on FMR should be removed for the analysis of the FMR parameters. Meanwhile, our result for the size dependance of ΔH was found to be contradictory to those reported by Dionne, where ΔH 1/r at a given surface roughness. This discrepancy appears to arise from the difference in the definition of reading the line width.

• Bulletin of the Korean Chemical Society
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• v.12 no.2
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• pp.182-188
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• 1991

The reactions of aniline with benzyl and phenacyl compounds are studied by the AM1 method. Two types of modeling were adopted: Cation-neutral, in which a proton is attached to the leaving group F and anion-neutral model, in which aniline was replaced by phenoxide with Cl as the leaving group. The cation-neutral model represented the reactvery well, reproducing the various solution-phase experimental results. In the benzyl system, the ${\pi}$-electrons of the two rings (X-ring in the nucleophile and Y-ring in the substrate) interact conjugatively in the transition state (TS) resulting in a bond contraction of the $C_{\alpha}-C_{Y1}$ bond (benzylic effect), whereas in the phenacyl system the ${\pi}$ electrons of the X-ring delocalizes more efficiently into the carbonyl group than into the Y-ring (resonance shunt effect) with a bond contraction of the $C_{\alpha}-C_{\beta}$ bond. The bond contraction in the benzylic effect was substantially greater than that in the resonance shunt effect. The TS was rather loose for benzyl while it was tighter for phenacyl system. Various bond length changes with substituents in the TS were, however, found to be irregular.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.5
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• pp.563-569
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• 2014

This article focuses on a hemispherical resonator gyro driven by the Coriolis effect. A hemispherical shell, called a resonator, is maintained in the resonance state by amplitude control and phase locking control. Parametric excitation has been used to control the amplitude. For rate measurement mode or FTR mode, nodal points have been kept to an amplitude of zero. Angular rate measurement has been demonstrated by rotating a resonator. Frequency mismatch between two stiffness principal axes is a major cause of low performance: vibrating pattern drift and reduced control effectiveness. This mismatch has been reduced significantly by the addition of small mass. A negative spring effect, which lowers resonance frequencies, has been verified experimentally.

• Journal of the Microelectronics and Packaging Society
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• v.7 no.4
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• pp.43-47
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• 2000

The etching characteristic of a tantalum thin film with pure chlorine plasma was studied using an electron cyclotron resonance etcher system. Optical emission actinometry (OEA) was used for the study of the etching mechanism of a tantalum thin film and optimum process condition was achieved by OEA study. Based on this mechanism, double step etching was performed and 0.15 $\mu\textrm{m}$ L & S was acquired successfully suppressing the microloading effect.

• Journal of the Korean Ceramic Society
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• v.22 no.1
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• pp.47-52
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• 1985

The effect of calcining temperature on planar coupling factor Kp resonance and antiresonance frequency of $Pb(Z_{0.53}Ti_{0.47})O_3$ doped with $Nb_2O_5$ has been investigated. The calcining temperature ranged from $700^{\circ}C$ to 110$0^{\circ}C$ The calcining temperature affected on antiresonance frequency more strongly than the resonance frequency. Therefore the Kp was almost entirely dependent upon the antiresonance frequency. The p and antiresonance frequency of the sample in creased with the calcining temperature reaching a maximum at about 90$0^{\circ}C$ When a poling electric field of 35KV/cm was applied to the sample calcined at 90$0^{\circ}C$ and sintered for two hours at 120$0^{\circ}C$ Kp attained a maximum value of 0.64 which is in good agreement with the results of other investigators.