• Journal of Korean Foot and Ankle Society
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• v.21 no.4
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• pp.174-178
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• 2017

Traumatic neuromas are rare benign tumors that are common after trauma or surgery and are usually accompanied by obvious symptoms of pain. Most reports show neuromas in the face, neck, and limbs, and the traumatic neuroma of the medial plantar nerve has rarely been reported. We encountered a traumatic neuroma of the medial plantar nerve after a deep laceration mimicking a foreign body granuloma. A small mass lesion was found around plantar aponeurosis with heterogeneous high signal intensity in the T2 fat suppression view and slightly enhanced intensity in the magnetic resonance imaging that suggested a foreign body granuloma. The lesion was diagnosed pathologically as a traumatic neuroma. A satisfactory clinical result was obtained after excision of the traumatic neuroma and burial of the proximal and distal stumps to the adjacent muscle at the secondary operation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.2
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• pp.95-101
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• 2008

This paper presents a novel bandpass filter design method for suppressing spurious response in the GSM band and effectively reducing the overall size with the unbalanced-conditioned metamaterials. Compared to the conventional bandpass filters based on half-or quarter-wave resonators, the CRLH(composite right/left-handed) bandpass filter works excellently in harmonic-suppression by 40$\sim$50 dB and 80 %-miniaturization using the zero-order resonators bridged by Inductive-coupling Inverters suggested first time. The proposed technique, with the equivalent circuit and dispersion diagram, is validated by performance predictions and experiments.

• Journal of The Korean Astronomical Society
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• v.47 no.5
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• pp.187-193
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• 2014

Recent cosmological observations indicate that the reionized universe may have started at around z = 6, where a significant suppression around $Ly{\alpha}$ has been observed from the neutral intergalactic medium. The associated neutral hydrogen column density is expected to exceed $10^{21}cm^{-2}$, where it is very important to use the accurate scattering cross section known as the Kramers-Heisenberg formula that is obtained from the fully quantum mechanical time-dependent second order perturbation theory. We present the Kramers-Heisenberg formula and compare it with the formula introduced in a heuristic way by Peebles (1993) considering the hydrogen atom as a two-level atom, from which we find a deviation by a factor of two in the red wing region far from the line center. Adopting a representative set of cosmological parameters, we compute the Gunn-Peterson optical depths and absorption profiles. Our results are quantitatively compared with previous work by Madau & Rees (2000), who adopted the Peebles approximation in their radiative transfer problems. We find deviations up to 5 per cent in the Gunn-Peterson transmission coefficient for an accelerated expanding universe in the red off-resonance wing part with the rest wavelength ${\Delta}{\lambda}{\sim}10{\AA}$.

• Journal of Medicine and Life Science
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• v.18 no.1
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• pp.16-19
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• 2021

Cushing's disease (CD) is a rare illness characterized by chronic hypercortisolism secondary to the overproduction of adrenocorticotropic hormone by a pituitary adenoma, which is associated with a high risk of developing serious complications, such as diabetes mellitus, cardiovascular disease, and emotional disorders. Endoscopic transsphenoidal surgery is performed for the treatment of CD, and was initially preferred over other types of treatments. However, the recurrence after pituitary surgery for CD is a common problem after an initial successful surgery. In microadenomas, the remission rates were higher than those of macroadenoma. This patient had a giant tumor that was greater than 4 cm in length on sella magnetic resonance imaging, and panhypopituitarism was detected using a combined pituitary stimulation test. After transsphenoidal surgery, the patient required temporary hormone replacement for a short period of time. After 1 year, he showed a normal cortisol response on the overnight dexamethasone suppression test and low morning cortisol levels. Therefore, we indicated that the patient was cured of giant macroadenoma with panhypopituitarism before surgery, and thus, reported this case.

• Structural Engineering and Mechanics
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• v.86 no.6
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• pp.751-764
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• 2023

In practical engineering such as aerial refueling pipes, the boundary of the fluid-conveying pipe is difficult to be completely immovable. Pipes under movable and immovable boundaries are controlled by different dominant nonlinear factors, where the boundary mobility will affect the nonlinear dynamic characteristics, which should be focused on for adopting different strategies for vibration suppression and control. The nonlinear dynamic instability characteristics of functionally graded fluid-conveying pipes lying on a viscoelastic foundation under movable and immovable boundary conditions are systematically studied for the first time. Nonlinear factors involving nonlinear inertia and nonlinear curvature for pipes with a movable boundary as well as tensile hardening and nonlinear curvature for pipes with an immovable boundary are comprehensively considered during the derivation of the governing equations of the principal parametric resonance. The stability boundary and amplitude-frequency bifurcation diagrams are obtained by employing the two-step perturbation- incremental harmonic balance method (TSP-IHBM). Results show that the movability of the boundary of the pipe has a great influence on the vibration amplitude, bifurcation topology, and the physical meanings of the stability boundary due to different dominant nonlinear factors. This research has guidance significance for nonlinear dynamic design of fluid-conveying pipe with avoiding in the instability regions.

• Journal of radiological science and technology
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• v.32 no.1
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• pp.95-99
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• 2009

The purpose of this research is to seek SPAIR's reversal time (TI) which satisfies two conditions ; maintaining the suppression ability of fat tissue and simultaneously minimizing the inhomogeneity of fat tissue in T2 high-speed spin echo 3.0T magnetic resonance image (MRI) of the brain, and to compare SPAIR with STIR which is fat-suppression technique. The reversal times (TI) of SPAIR protocol are set to 1/2, 1/3, 1/6 and 1/12 of SPAIR TR (420 msec), namely 210 msec (8 people), 140 msec (26 people), 70 msec (26 people) and 35 msec (18 people) and STIR TI is set with 250 msec (26 people). With these parameter sets, we acquired the axis direction 104 images of the brain. In ROI ($50\;mm^2$) of output image, signal intensities of the fatty tissue, the muscular tissue, and the background were measured and the CNRs of fatty tissue and the muscular tissue were calculated. The inhomogeneity of the fatty tissue is SD/mean, where SD is the standard deviation and 'mean' is a average fatty tissue signal. Consequently, SPAIR TI is determined on either 1/3 or 1/6 of TR (420 ms) ; 140 ms or 70 ms. Because the difference of statistics in fat-suppression ability and inhomogeneity of fatty tissue is very small (p < 0.001), Selecting 140 ms seems to be better choice for the image quality. Meanwhile, Comparing SPAIR (TI : 140 ms) with STIR, the fat-suppression is not able to be considered statistically (p < 0.252), but the image quality is able to be considered statistically (p < 0.01). In conclusion, SPAIR is better than STIR in the image quality.

• Journal of Digital Convergence
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• v.12 no.10
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• pp.385-390
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• 2014

This research is conducted to identify whether an m-DIXON technique which is useful for an abdomen MRI examination compared with an existing e-THRIVE technique is a clinically useful or not. There was evaluated quantitative and qualitative to 84 subjects who had abdomen MRI exam due to their liver disease were conducted during a period from September in 2013 to February in 2014. First of all the quantitative evaluation, the m-DIXON technique's SNR was $90.42{\pm}16.90$ and the e-THRIVE technique was $60.42{\pm}11.54$ and the m-DIXON technique's CNR was $52.38{\pm}22.58$ and the e-THRIVE technique was $46.31{\pm}20.25$. Secondly in the qualitative evaluation, the m-DIXON technique's image quality was $4.06{\pm}0.34$, a artifact was $3.64{\pm}0.22$, and fat suppression was $4.16{\pm}0.15$, the e-THRIVE technique's image quality was $3.14{\pm}0.35$, a artifact was $3.06{\pm}0.38$, fat suppression was $3.14{\pm}0.30$. In conclusion, m-DIXON technique for abdomen MRI examination showed superiority over both SNR as a quantitative anaylsis, CNR and a qualitative analysis.

• Investigative Magnetic Resonance Imaging
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• v.18 no.2
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• pp.87-106
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• 2014

Purpose : To describe how a robust implementation of a radial 3D gradient-echo sequence with stack-of-stars sampling can be achieved, to review the imaging properties of radial acquisitions, and to share the experience from more than 5000 clinical patient scans. Materials and Methods: A radial stack-of-stars sequence was implemented and installed on 9 clinical MR systems operating at 1.5 and 3 Tesla. Protocols were designed for various applications in which motion artifacts frequently pose a problem with conventional Cartesian techniques. Radial scans were added to routine examinations without selection of specific patient cohorts. Results: Radial acquisitions show significantly lower sensitivity to motion and allow examinations during free breathing. Elimination of breath-holding reduces failure rates for non-compliant patients and enables imaging at higher resolution. Residual artifacts appear as streaks, which are easy to identify and rarely obscure diagnostic information. The improved robustness comes at the expense of longer scan durations, the requirement for fat suppression, and the nonexistence of a time-to-center value. Care needs to be taken during the configuration of receive coils. Conclusion: Routine clinical use of radial stack-of-stars sequences is feasible with current MR systems and may serve as substitute for conventional fat-suppressed T1-weighted protocols in applications where motion is likely to degrade the image quality.

• Investigative Magnetic Resonance Imaging
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• v.7 no.2
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• pp.108-115
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• 2003

Purpose : To evaluate the effect of the gradient switching noise on the ECD source localization with the EEG data recorded during the MRI scan. Materials and Methods : We have fabricated a spherical EEG phantom that emulates a human head on which multiple electrodes are attached. Inside the phantom, electric current dipole(ECD) sources are located to evaluate the source localization error. The EEG phantom was placed in the center of the whole-body 3.0 Tesla MRI magnet, and a sinusoidal current was fed to the ECD sources. With an MRI-compatible EEG measurement system, we recorded the multi channel electric potential signals during gradient echo single-shot EPI scans. To evaluate the effect of the gradient switching noise on the ECD source localization, we controlled the gradient noise level by changing the FOV of the EPI scan. With the measured potential signals, we have performed the ECD source localization. Results : The source localization error depends on the gradient switching noise level and the ECD source position. The gradient switching noise has much bigger negative effects on the source localization than the Gaussian noise. We have found that the ECD source localization works reasonably when the gradient switching noise power is smaller than $10\%$ of the EEG signal power. Conclusion : We think that the results of the present study can be used as a guideline to determine the degree of gradient switching noise suppression in EEG when the EEG data are to be used to enhance the performance of fMRI.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.10
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• pp.80-89
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• 2008

Patch antennas with an array of pins interconnecting the patch and the ground (Pin array patch antennas) are fabricated and their characteristics are measured. The radiation characteristics of pin array patch antennas are compared to those of conventional patch antennas. The suppressions of the radiation in horizontal directions in E-plane and H-plane are more than 10 dB and 4 dB, respectively. The forward radiation is increased, while the backward radiation is decreased. The directivity is improved because the half-power beamwidth of radiation patterns in both E-plane and H-plane is reduced. The resonance frequency of a pin array patch antenna increases as the pin radius of a pin amy patch antenna increases. An optimum pin radius of a pin array patch antenna exists for the maximum suppression of the radiation in horizontal directions.