• Investigative Magnetic Resonance Imaging
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• v.23 no.3
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• pp.259-263
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• 2019

Although many imaging modalities can play some roles in the diagnosis of vertebral artery dissection (VAD), digital subtraction angiography (DSA) remains the gold standard method, with the highest detection rate and ability to assist in planning for endovascular treatment. However, this tool is often avoided in children because its invasive nature and it exposes them to radiation. High resolution magnetic resonance imaging (HR-MRI) have been suggested to be a reliable and non-invasive alternative, but it has never been discussed in children in whom vertebral artery dissection is a rare condition. In this report, we evaluate a case of a 2-year-old child who initially presented with cerebellar symptoms, and was early diagnosed with vertebral artery dissection using HR- MRI and was successfully treated.

• Korean Journal of Radiology
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• v.20 no.5
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• pp.695-708
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• 2019

Atrial fibrillation (AF) is the most common arrhythmia associated with the risk of morbidity and mortality in clinical patients. AF is considered as an arrhythmia type that develops and progresses through close connection with cardiac structural arrhythmogenic substrates. Since the introduction of catheter ablation-mediated electrical isolation of arrhythmogenic substrates, cardiac imaging indicates improved treatment outcome and prognosis with appropriate candidate selection, ablation catheter guidance, and post-ablation follow-up. Currently, cardiac computed tomography (CCT) and cardiovascular magnetic resonance (CMR) imaging are essential in the case management of AF at both pre-and post-procedural stages of catheter ablation. In this review, we discuss the roles and technical considerations of CCT and CMR imaging in the management of patients with AF undergoing catheter ablation.

• Journal of Environmental Science International
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• v.19 no.3
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• pp.371-377
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• 2010

The purpose of this study is to investigate treatment efficiency in dyeing wastewater treatment by the high rate aeration system(HRA) and a combination of the HRA with magnetized wastewater treatment system(MWS). At the hydraulic retention time of 16hr, 24hr, 30hr, BOD removal efficiencies of HRA system were 93%, 96% and 98%, combination of the HRA with MWS system were 94%, 96.8% and 98.2%, respectively. In ease of COD, at the hydraulic retention time of 16hr, 24hr, 30hr, COD removal efficiencies of HRA system were 66%, 77.1% and 83.1%, combination of the HRA with MWS system were 70.2%, 80.1% and 86.6%, respectively. The comparison of the HRA and combination of the HRA with MWS, effluent BOD of the former was 22.7mg/${\ell}$ and the latter was 19.4mg/${\ell}$, theretore biological treatment efficiency identified to increase by the MWS.

• Progress in Superconductivity and Cryogenics
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• v.21 no.2
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• pp.31-35
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• 2019

Andong-dam was built up in 1967 and it is one of the biggest dams in Korea. Previous studies showed that the sediments are highly contaminated with heavy metals such as arsenic, cadmium, and lead. Many research projects are going on to find out the source of the contamination, to evaluate the toxicities to ecosystem, to estimate the volume of sediment to be treated and to find out a good remediation method. Reports show that the sediment is highly contaminated and the main contamination source is supposed to be abandoned mines and a zinc refinery located upper stream of the river. A magnetic separation has been tested as a treatment method for the dredged sediment. Lab scale test showed that the magnetically captured portion is about 10% in weight but the contamination of heavy metal is much higher than the contamination of the passed portion. This indicates that a magnetic separation could be applied for the purpose of reduction of sediment to be treated and for increasing the volume of low toxic sediments which can be dumped as general waste. A magnetic separation using a HGMS has been tested for the sediment with variable magnetic field and the results showed the higher magnetic field increase the captured portion but the concentrating effect of heavy metal was weakened. Further study is needed to establish a useful technology and optimization between decontamination and reduction of sediment volume.

• Biomolecules & Therapeutics
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• v.19 no.2
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• pp.261-266
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• 2011

As recent reports suggest that nanoparticles may penetrate into cell membrane and effect DNA condition, it is necessary to assay possible cytotoxic and genotoxic risk. Three different sizes of magnetic nanoparticle silica (MNP@$SiO_2$) (50, 100 and 200 nm diameter) were tested for cytotoxicity and DNA damage using L5178Y cell. MNP@$SiO_2$ had constant physicochemical characteristics confirmed by transmission electron microscope, electron spin resonance spectrometer and inductively coupled plasma-atomic emission spectrometer for 48 h. Treatment of MNP@$SiO_2$ induced dose and time dependent cytotoxicity. At 6 h, 50, 100 or 200 nm MNP@$SiO_2$ decreased significantly cell viability over the concentration of 125 ${\mu}g/ml$ compared to vehicle control (p<0.05 or p<0.01). Moreover, at 24 h, 50 or 100 nm MNP@$SiO_2$ decreased significantly cell viability over the concentration of 125 ${\mu}g/ml$(p<0.01). And treatment of 200 nm MNP@$SiO_2$ decreased significantly cell viability at the concentration of 62.5 ${\mu}g/ml$ (p<0.05) and of 125, 250, 500 ${\mu}g/ml$ (p<0.01, respectively). Furthermore, at 48 h, 50, 100 or 200 nm MNP@$SiO_2$ decreased significantly cell viability at the concentration of 62.5 ${\mu}g/ml$ (p<0.05) and of 125, 250, 500 ${\mu}g/ml$ (p<0.01, respectively). Cellular location detected by confocal microscope represented they were existed in cytoplasm, mainly around cell membrane at 2 h after treatment of MNP@$SiO_2$. Treatment of 50 nm MNP@$SiO_2$ significantly increased DNA damage at middle and high dose (p<0.01), and treatment of 100 nm or 200 nm significantly increased DNA damage in all dose compared to control (p<0.01). Taken together, treatment of MNP@$SiO_2$ induced cytotoxicity and enhanced DNA damage in L5178Y cell.

• Korean Journal of Radiology
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• v.22 no.1
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• pp.23-40
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• 2021

In pancreatic cancer, imaging plays an essential role in surveillance, diagnosis, resectability evaluation, and treatment response evaluation. Pancreatic cancer surveillance in high-risk individuals has been attempted using endoscopic ultrasound (EUS) or magnetic resonance imaging (MRI). Imaging diagnosis and resectability evaluation are the most important factors influencing treatment decisions, where computed tomography (CT) is the preferred modality. EUS, MRI, and positron emission tomography play a complementary role to CT. Treatment response evaluation is of increasing clinical importance, especially in patients undergoing neoadjuvant therapy. This review aimed to comprehensively review the role of imaging in relation to the current treatment strategy for pancreatic cancer, including surveillance, diagnosis, evaluation of resectability and treatment response, and prediction of prognosis.

• Investigative Magnetic Resonance Imaging
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• v.22 no.1
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• pp.18-25
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• 2018

Purpose: To investigate the various imaging factors associated with aggravation of lumbar disc herniation (LDH) and develop a scoring system for prediction of LDH aggravation. Materials and Methods: From 2015 to 2017, we retrospectively reviewed the magnetic resonance imaging (MRI) findings of 60 patients (30 patients with aggravated LDH and 30 patients without any altered LDH). Imaging factors for MRI evaluation included the level of LDH, disc degeneration, back muscle atrophy, facet joint degeneration, ligamentum flavum thickness and interspinous ligament degeneration. Flexion-extension difference was measured with simple radiography. The scoring system was analyzed using receiver operating characteristic (ROC) analysis. Results: The aggravated group manifested a higher grade of disc degeneration, back muscle atrophy and facet degeneration than the control group. The ligamentum flavum thickness in the aggravated group was thicker than in the group with unaltered LDH. The summation score was defined as the sum of the grade of disc degeneration, back muscle atrophy and facet joint degeneration. The area under the ROC curve showing the threshold value of the summation score for prediction of aggravation of LDH was 0.832 and the threshold value corresponded to 6.5. Conclusion: Disc degeneration, facet degeneration, back muscle atrophy and ligamentum flavum thickness are important factors in predicting aggravation of LDH and may facilitate the determination of treatment strategy in patients with LDH. The summation score is available as supplemental data.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.7
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• pp.1262-1269
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• 2002

It is inevitable to evaluate the life of turbine rotor because the operating periods of power plants need to be extended. For the test, seven kinds of specimens with different degradation levels were prepared by the isothermal heat treatment at $630^{\circ}C$. Magnetic methods utilizing Barkhausen noise coercive force($BN_c$) were applied to detect the degradation caused by thermal aging. Magnetic property of material is related with domain dynamics and that is affected by the microstructure of material. Therefore $BN_c$ is very sensitive to the microstructure change of the material. With the increase of degradation, $BN_c$ was decreased and this phenomenon is considered due to precipitations and grain size. The result was compared with Vickers hardness($H_v$) and coercive force($H_c$) to detect the relative variation, and was related with $H_v$ and YS to estimate the change of the mechanical properties with the degradation.

• Investigative Magnetic Resonance Imaging
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• v.20 no.1
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• pp.75-79
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• 2016

We report a case of perivalvular abscess in a 66-year-old man with infective endocarditis, diagnosed by late gadolinium-enhanced (LGE) cardiovascular magnetic resonance (CMR) imaging. No clinical features suspicious of infective endocarditis were noted, however, transthoracic echocardiography revealed non-specific echogenic focal wall thickening at mitral-aortic intervalvular fibrosa. Perivalvular abscess in the aortic valve was demonstrated as focal wall thickening between the anterior mitral leaflet and the non-coronary cusp of the aortic valve with peripheral enhancement and central low signal intensity on LGE CMR imaging. Other features suggestive of infective endocarditis, such as neither vegetation nor valvular perforation were present. The perivalvular abscess did not grow after intensive intravenous antibiotics therapy, and the patient was discharged without surgical treatment. CMR with LGE provided an early accurate diagnosis of perivalvular abscess. The diagnosis of perivalvular abscess using LGE CMR imaging was not previously reported in Korea.

• Journal of Magnetics
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• v.20 no.4
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• pp.336-341
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• 2015

MnBi alloys were fabricated by arc melting and annealing at 573 K. The heat treatment enhanced the content of the low-temperature phase (LTP) of MnBi up to 83 wt%. The Bi-excess assisted LTP MnBi alloys were used in the hybridization with the Nd-Fe-B commercial Magnequench ribbons to form the hybrid magnets (100-x)NdFeB/xMnBi, x = 20, 30, 40, 50, and 80 wt%. The as-milled powder mixtures of Nd-Fe-B and MnBi were aligned in a magnetic field of 18 kOe and warm-compacted to anisotropic and dense bulk magnets at 573 K by 2,000 psi for 10 min. The magnetic ordering of two hard phase components strengthened by the exchange coupling enhanced the Curie temperature ($T_c$) of the magnet in comparison to that of the powder mixture sample. The prepared hybrid magnets were highly anisotropic with the ratio $M_r/M_s$ > 0.8. The exchange coupling was high, and the coercivity $_iH_c$ of the magnets was ~11-13 kOe. The maximum value of the energy product $(BH)_{max}$ was 8.4 MGOe for the magnet with x = 30%. The preparation of MnBi alloys and hybrid magnets are discussed in details.