• 한국생물공학회:학술대회논문집
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• 2005.04a
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• pp.497-498
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• 2005

• Investigative Magnetic Resonance Imaging
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• v.21 no.2
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• pp.91-96
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• 2017

Purpose: To describe technical methods for functional magnetic resonance imaging (fMRI) study with arterial spin labeling (ASL) compared to blood oxygenation level-dependent (BOLD) technique and discuss the potential of ASL for research and clinical practice. Materials and Methods: Task-based (n = 1) and resting-state fMRI (rs-fMRI) (n = 20) were performed using ASL and BOLD techniques. Results of both techniques were compared. Results: For task-based fMRI with finger-tapping, the primary motor cortex of the contralateral frontal lobe and the ipsilateral cerebellum were activated by both BOLD and ASL fMRI. For rs-fMRI of sensorimotor network, functional connectivity showed similar results between BOLD and ASL. Conclusion: ASL technique has potential application in clinical and research fields because all brain perfusion imaging, CBF measurement, and rs-fMRI study can be performed in a single acquisition.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.27 no.2
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• pp.148-154
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• 2017

This paper discussed design for resonance avoidance of sensor plates of loose-parts monitoring systems (LPMS) in nuclear power plants (NPP). An LPMS monitors impact of loose parts in primary loop of NPP by using accelerometers, which is mounted on sensor plates. Resonance of the plates may cause false alarms at frequencies over 10 kHz, which can be misunderstood as impact signals of loose parts with small mass and cause unnecessary response of NPP operators. Modal analysis was carried out for the existing sensor plate and design parameters affecting natural frequencies were chosen. Frequency response functions of plates were analyzed by changing the parameters and the optimized plate design for avoiding resonance was determined. Experiments was carried out for the plate specimen with improved design and verified the proposed approach and design.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.311-315
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• 2000

A numerical investigation is made of time-dependent buoyant convection in a square of a non-Boussinesq fluid. The density-temperature$({\rho}-T)$ relation is modeled by a quadratic function, with the maximum density ${\rho}_M$ at temperature $T_M$. The horizontal walls of the square are insulated, and a pulsating temperature $T_H=T_M+{\Delta}T'\;sin({\omega}{\tau})$ is imposed on the hot vertical sidewall. The temperature at the cold wall $T_c$ is constant. Extensive numerical solutions to the governing Navier-Stokes equations are portrayed. Resonance is identified by monitoring the amplitude of the mid-plane Nusselt number, $A(Nu^*)$. The primary resonance frequency is found by matching ${\omega}$ to the nondimensional basic mode $N_1$ of internal gravity oscillations. Due to the quadratic$({\rho}-T)$ relationship, the effective pulsation frequency for density, $2{\omega}$, is meaningful, which brings forth the secondary resonance frequency, i.e., $2{\omega}=N_1$

• Investigative Magnetic Resonance Imaging
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• v.20 no.2
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• pp.114-119
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• 2016

We report a case of vegetation in a 4-year-old female with infective endocarditis, diagnosed by late gadolinium-enhanced (LGE) cardiovascular magnetic resonance (CMR) imaging. The patient had a history of primary closure for ventricular septal defect and presented with mild febrile sensation. No remarkable clinical symptoms or laboratory findings were noted; however, transthoracic echocardiography demonstrated a 14 mm highly mobile homogeneous mass in the right ventricle. On LGE CMR imaging, the mass showed marginal rim enhancement, which suggested the diagnosis of vegetation rather than thrombus. The extracellular volume fraction (${\geq}42%$) of the lesion was higher than that of normal myocardium. Based on the patient's clinical history of congenital heart disease and pathologic confirmation of the lesion, a diagnosis of infective endocarditis with vegetation was made.

• Investigative Magnetic Resonance Imaging
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• v.23 no.4
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• pp.390-394
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• 2019

Hemosiderosis is characterized by the deposition of excess iron in body tissues. The choroid plexus is an important part of the central nervous system that can be the primary site of iron overload. T2*-weighted gradient echo (GRE) sequence provides high sensitivity for demonstrating cerebral microhemorrhagic foci and iron deposition. In the present study, we describe the case of a 15-year-old boy with acute lymphoblastic leukemia, in whom repeated transfusion led to iron accumulation in the brain. GRE sequence effectively demonstrated hemosiderin deposition in the choroid plexus.

• Investigative Magnetic Resonance Imaging
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• v.25 no.1
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• pp.35-42
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• 2021

Purpose: To evaluate and analyze the adequacy of breast magnetic resonance imaging (MRI)s taken before publication of the 2018 recommendation in South Korea. Materials and Methods: We enrolled 87 cases of breast MRIs, from January 2010 to November 2013, taken at external hospitals in the study. Breast MRI protocol elements are divided into three categories based on the recommendation by the Breast Imaging Study Group of the Korean Society of Magnetic Resonance: (1) Essential elements for breast MRI protocol; (2) Element to consider when evaluating imaging quality; and (3) Optional element for breast MRI protocol. Also, we divided enrolled cases into three groups based on their conducting locations -- (1) Primary hospitals, (2) Secondary hospitals, and (3) Tertiary hospitals-and analyzed them for the adequacy of imaging protocols based on the 2018 recommendation. We used a Chi-square test and Fisher's exact test to identify differences between categorical variables. Results: Over 98% of the criteria for 'essential elements for breast MRI protocol' were satisfied when compared with the 2018 Recommendation. Over 96% of the criteria for 'elements to consider when evaluating imaging quality' were also satisfied, except for the slice thickness (83.9%). Optional elements for breast MRI protocol were satisfied with various percentages. There were no statistically significant differences between groups of tertiary, secondary, and primary hospitals; however, 3 tesla of MRI (P = 0.04), subtraction image protocol (P = 0.032), and DWI protocol (P = 0.03) were used more frequently in the tertiary hospitals than in the others. Conclusion: We found that the categories of 'essential elements' and 'elements to consider when evaluating imaging quality' were satisfied at 98% and 96%, respectively, when compared with the 2018 Recommendation by the Breast Imaging Study Group of the Korean Society of Magnetic Resonance.

• Investigative Magnetic Resonance Imaging
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• v.12 no.2
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• pp.89-99
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• 2008

Imaging assessment of prostate cancer is one of the most difficult sections of oncology imaging. Detecting, localizing and staging of the primary prostate cancer by preoperative imaging are still challenging for the radiologist. Magnetic resonance (MR) imaging provides excellent soft tissue contrast and is widely used for solid organ imaging, but results of preoperative imaging of the prostate gland with conventional MR imaging is unsatisfactory. Positron emission tomography and computed tomography (PET/CT) is the cornerstone in oncology imaging, but some limitations prohibit the assessment of primary prostate cancer with PET or PET/CT. Recent studies to overcome these insufficient accuracies of imaging evaluation of primary prostate cancers with advanced MR techniques and PET and PET/CT are reported. In this article, we review the imaging findings of prostate cancer on variable modalities, focused on MR imaging and PET/CT.

• Journal of Korean Neurosurgical Society
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• v.41 no.1
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• pp.39-42
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• 2007

Primary intracranial melanoma is uncommon. These tumors most commonly occur at the temporal lobe, cerebellum and cerebellopontine angle. We report a case of intracranial malignant melanoma of the occipital lobe in a 60-year-old man who presented with headache and visual disturbance. The mass showed hyperintensity on T1-weighted images and hypointensity on T2-weighted magnetic resonance images. He underwent gross total removal of tumor and received radiotherapy. Follow-up imaging studios showed neither recurrence nor any signs of residual disease for 4 months.

• Journal of Korean Neurosurgical Society
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• v.39 no.5
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• pp.382-384
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• 2006

We report a rare case of primary intradural extramedullary myxopapillary ependymoma of the spinal cord. A 45-year-old woman was admitted to the author's institution with a history of progressive paraparesis[grade IV/IV] with back pain. Neurologic examination revealed decreased sensation below T12 sensory dermatome level. Magnetic resonance imaging[MRI] revealed an intermediate enhanced intradural extramedullary tumor extending from T12. Total resection of the tumor was achieved by T12 laminectomy. Intraoperatively, there was no finding of attachment to rootlet and dura. Histopathological examination identified the tumor as a myxopaillary ependymoma. To the best of my knowledge, this is the first reported case of primary intradural extramedullary ependymoma in Korea.