• Korean Journal of Digital Imaging in Medicine
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• v.14 no.2
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• pp.57-61
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• 2012

To compare the accuracy of breath-hold magnetic resonance imaging sequences to establish the most effective superparamagnetic iron oxide-enhanced sequence for detection of hepatic metastases. A total of 100 patients(50men and 50women, mean age: 60years) with liver disease(including malignant and benign liver lesions) were investigated at 3.0T machine (GE, General Electric Medical System, Excite HD) with 8Ch body coil. Pulse sequence for MR imaging decided to the FS-T2-FSE-RT(TR/TE/Thick./Freq./Phase=12857ms/100ms/7mm/512/384), MGRE(TR/TE/Thick./Freq./Phase=100ms/9.7ms/7mm/384/288), in-out of phase echo(TR/$TE_1$, $TE_2$/Thick./Freq./Phase=140ms/2.4, 5.8ms/7mm/352/300), Images obtained before the injection of SPIO. Six sequences were optimized for lesion detection: FS-T2-FSE-RT, multigradient recalled echo data image(MGRE), T2-weighted MGRE with an 9.7msec echo time. Images were reviewed independently by five blinded observers. The accuracy of each sequence was measured by using picture archiving communication system analysis. All results were correlated with findings at multidectator computed tomography examination. Differences between the mean results of the six observers were measured by using paired student t-test analysis. Postcontrast T2-weighted MGRE sequences were the most accurate and were significantly superior to postcontrast FS-T2-FSE-RT, T2-weighted MGRE, in-out of phase MR sequences(p < .05). For all lesions that were malignant or smaller than 1 cm, respectively, contrast to noise ratio of pre and postcontrast sequences were -1and -0.3 for T2-weighted FSE, 0.53 and 4.5 in-out of phase, 7, 7.08, 5.08, 3.32, 1.7, 1.16, 0.79, 0.68 for GRE with 2.9, 7.5, 12.1, 16.6, 21.2, 25.8, 30.4, 35.0 TE values. Breath-hold various TE precontrast sequences offer improvement in sensitivity compared with fixed multigradient recalled echo sequences alone.

• Journal of the Korea Convergence Society
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• v.5 no.3
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• pp.23-27
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• 2014

In recent times, there is an increasing interest in wireless charge of smartphones and devices, and many companies are developing wireless charges. The range of application of wireless charge would be expanded to almost all electronics, including not only mobile devices, but also notebook computers and vacuum cleaners. On-line electric vehicles are to be launched in the market this year in a massive scale. As such wireless charge-related markets are inexhaustible. Wireless charge is included in the world's top 10 promising technologies, and its rapid growth is expected to have annual growth by more than 100%. However, there's a need to establish a safe environment, by analyzing security threats to technical limitations and harmfulness to human body, and arrange institutional compliments. The development of communication method for a variety of wireless charging are delivering comfortable and safe information. This paper aims to examine the factors to threaten electric vehicle, which are usually intruded through network system and analyzes security threats to and security requirements for magnetic resonance mode-based wireless charge in mobile devices, and suggests security requirements.

• Korean Journal of Acupuncture
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• v.25 no.4
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• pp.175-185
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• 2008

Objective : Acupuncture (from the Latin acus, "needle," and pungere, "to prick") is a technique of inserting and manipulating fine needles at specific points on the body. As a placebo acupuncture needle device was developed based on the visual impact of needling, it has been raised that it is useful only when acupuncture points and needling are visible to subjects. To examine the visual factor of the placebo acupuncture, the present study was aimed to compare the blinding index of the verum and placebo acupuncture between masked and unmasked situation. Methods : Thirty-six patients were randomly alloted to be stimulated with a verum or placebo acupuncture in a cross-over design. They were asked to guess a right answer whether they were stimulated with the verum or placebo acupuncture at LI4 in an unmasked or masked situation. The penetrating, pain, and deqi sensations were also measured after the stimulation using modified visual analogue scale. Results : The correct answer rate of the placebo acupuncture was 22.2% and 16.7% in an unmasked and masked situation, respectively (P>0.767). The blinding index of the placebo acupuncture was -0.56 (95%CI -0.84 to -0.27) and -0.67 (95%CI -0.91 to -0.42) in an unmasked and masked situation, respectively. The penetrating and deqi sensation of the verum acupuncture were significantly higher than those of the placebo acupuncture in both unmasked and masked situation. The pain sensation of the verum acupuncture was significantly higher than that of the placebo acupuncture in masked situation, but not in unmasked situation. Conclusion : Blinding of the placebo acupuncture was successful both in the unmasked and masked situation. These finding indicate that visual factor might not play a critical role in blinding of the placebo needle. We suggest that placebo needle would be also useful in a functional magnetic resonance imaging scan even when the subject could not see the placebo needle.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.12
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• pp.1844-1851
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• 2017

As the capacity of the wireless power transmission increases, a higher supply current which may induce current in nearby conductive parts requires. Induced current may affect electric shock to the human body and malfunction of the electrical equipment. In order to prevent such induced phenomena as a risk factor, shielding is required between the source of the wireless power transmission and the conductive parts. The resonance frequency for the large capacity wireless power transmission has the wavelength of several hundred meters, so most environments are included in the near-field area. By wave impedance, the electric field has higher density in the near-field area and needs to be analyze for protecting. For this purpose, it is necessary to select a substance having a larger electric conductivity and optimized shielding structure. In this paper, an aluminum base shielding structure was presented to conduct experiments on thickness, position, and heat dissipation. In the 35 kW, 60 kHz environments, the optimized 5T Al base shielding structure attenuates the induced current to 43 %.

• Membrane Journal
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• v.15 no.1
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• pp.8-14
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• 2005

The hyaluronic acid (HA) with excellent biocompatibility can be combined with the monomer polylactide with good biodegradability to produce biocompatible materials which can control the period of degradation in a human body. By freeze drying method, HA and the lactic acid, monomer of polylactide, or lactide, the ester dimer of polylactide, were crosslinked with crosslinking agent, l-ethyl-3-(3-dimethyl aminopropyl) carbodiimide. The analysis of infrared spectroscopy showed that the ester linkage was formed and the analysis of nuclear magnetic resonance (NMR) spectroscopy showed that the ester linkage was due to the reaction of lactic acid and HA. The conversion (6∼32%) and degree of crosslinking (4∼19%) increased but the selectivity was almost constant at 62% as the mole ratio of LA to HA increased from 1 to 10 in the crosslinking reaction. The brittleness became more pronounced and the rate of degradation became faster with more addition of lactic acid resulting from the higher ratio of LA to HA, and the swelling ratio was in the range of 500 to 2000%.

• Journal of Korean Neurosurgical Society
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• v.30 no.sup1
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• pp.20-24
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• 2001

Object : We intended to investigate the relationship between the degree of injury on MRI and the outcome of the patients with diffuse axonal inury. Method : From january, 1995 to march, 1999, 22 patients were supposed to have diffuse axonal injuries by means of their neurologic signs and MRI. We investigated their prognosis according to CT, MRI and initial neurologic findings. Result : 1) The lesions were mainly located at white matter of cerebrum, corpus callosum, brainstem, and basal ganglia. 2) The lesions of white matter were most commonly in the frontal lobe and temporal lobe. 3) The majority of corpus callosal lesions were located in the posterior body and splenium, but anterior corpus callosal lesions combined with posterior lesions were not found. 4) Brainstem lesions, all non-hemorrhagic, were mostly located in the dorsolateral aspect, not be found on CT. 5) The brainstem lesions were found in 10 cases among total 22 cases, and corpus callosal lesions were accompanied with 8 cases of brainstem lesions. 6) The patients with brainstem lesions had worse prognosis. Conclusion : It is important and reasonable to take brain MRI to identify the brainstem lesions in any cases of suspicious diffuse axonal injury, and we should remind that the diffuse axonal injury with stem lesion has worse prognosis.

• Korean Journal of Metals and Materials
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• v.50 no.5
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• pp.401-406
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• 2012

When viewed using a magnetic resonance imaging (MRI) system, invasive materials inside the human body, in many cases, severely distort the MR image of human tissues. The degree of the MR image distortion increases in proportion not only to the difference in the susceptibility between the invasive material and the human tissue, but also to the intensity of the magnetic field induced by the MRI system. In this study, by blending paramagnetic Ti particles with diamagnetic graphite, we synthesized $Ti_{100-x}C_x$ composites that can reduce the artifact in the MR image under the high-strength magnetic field. Of the developed composites, $Ti_{70}C_{30}$ showed the magnetic susceptibility of ${\chi}=67.6{\times}10^{-6}$, which corresponds to 30% of those of commercially available Ti alloys, the lowest reported in the literature. The level of the MR image distortion in the vicinity of the $Ti_{70}C_{30}$ composite insert was nearly negligible even under the high magnetic field of 4.7 T. In this paper, we reported on a methodology of designing new structural materials for bio-applications, their synthesis, experimental confirmation and measurement of MR images.

• Journal of Veterinary Science
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• v.22 no.1
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• pp.7.1-7.13
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• 2021

Background: Niemann-Pick disease type C (NPC) is caused by the mutation of NPC genes, which leads to the abnormal accumulation of unesterified cholesterol and glycolipids in lysosomes. This autosomal recessive disease is characterized by liver dysfunction, hepatosplenomegaly, and progressive neurodegeneration. Recently, the application of induced neural stem cells (iNSCs), converted from fibroblasts using specific transcription factors, to repair degenerated lesions has been considered a novel therapy. Objectives: The therapeutic effects on NPC by human iNSCs generated by our research group have not yet been studied in vivo; in this study, we investigate those effects. Methods: We used an NPC mouse model to efficiently evaluate the therapeutic effect of iNSCs, because neurodegeneration progress is rapid in NPC. In addition, application of human iNSCs from NPC patient-derived fibroblasts in an NPC model in vivo can give insight into the clinical usefulness of iNSC treatment. The iNSCs, generated from NPC patientderived fibroblasts using the SOX2 and HMGA2 reprogramming factors, were transplanted by intracerebral injection into NPC mice. Results: Transplantation of iNSCs showed positive results in survival and body weight change in vivo. Additionally, iNSC-treated mice showed improved learning and memory in behavior test results. Furthermore, through magnetic resonance imaging and histopathological assessments, we observed delayed neurodegeneration in NPC mouse brains. Conclusions: iNSCs converted from patient-derived fibroblasts can become another choice of treatment for neurodegenerative diseases such as NPC.

• Perinatology
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• v.29 no.4
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• pp.189-194
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• 2018

Congenital neuroblastoma is a rare disease. Placental metastasis is extremely rare and poor prognosis has been reported in neonates. Mirror syndrome could occur in mother with placental metastasis with possibilities of hypertension and edema. We report a case of detection of left suprarenal mass in fetus at $31^{+5}weeks^{\prime}$ gestation. Mother presented with palpitation, edema, headache, and hypertension. Maternal 24 hours urine vanillylmandelic acid (VMA) and normetanephrine (NME) level at 34 weeks' gestation were elevated. Consequently, emergent cesarean section was done. Based on abdominal ultrasonography and whole body magnetic resonance imaging, left adrenal tumor with liver metastasis was suspected. Neuroblastoma was confirmed by liver and placenta biopsy. Chemotherapy was started with Pediatric Oncology Group 9243 at day 7 and changed into Children's Oncology Group 3961 due to cholestasis and poor response during 2nd cycle. Plasma exchange was done for aggravated direct hyperbilirubinemia. The baby expired at 73 days due to multi-organ failure. Maternal symptoms were completely resolved in 2 weeks after delivery along with normalization of the elevated level of VMA and NME. We report a first case of mirror syndrome in Korean mother and fetus resulting from metastatic congenital neuroblastoma to placenta.

• Hip & pelvis
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• v.30 no.4
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• pp.219-225
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• 2018

Purpose: Ischiofemoral impingement (IFI)-primarily diagnosed by magnetic resonance imaging (MRI)-is an easily overlooked disease due to its low incidence. The purpose of this study was to evaluate the usefulness of false profile view as a screening test for IFI. Materials and Methods: Fifty-eight patients diagnosed with IFI between June 2013 and July 2017 were enrolled in this retrospective study. A control group (n=58) with matching propensity scores (age, gender, and body mass index) were also included. Ischiofemoral space (IFS) was measured as the shortest distance between the lateral cortex of the ischium and the medial cortex of lesser trochanter in weight bearing hip anteroposterior (AP) view and false profile view. MRI was used to measure IFS and quadratus femoris space (QFS). The receiver operating characteristics (ROC), area under the ROC curve (AUC) and cutoff point of the IFS were measured by false profile images, and the correlation between the IFS and QFS was analyzed using the MRI scans. Results: In the false profile view and hip AP view, patients with IFI had significantly decreased IFS (P<0.01). In the false profile view, ROC AUC (0.967) was higher than in the hip AP view (0.841). Cutoff value for differential diagnosis of IFI in the false profile view was 10.3 mm (sensitivity, 88.2%; specificity, 88.4%). IFS correlated with IFS (r=0.744) QFS (0.740) in MRI and IFS (0.621) in hip AP view (P<0.01). Conclusion: IFS on false profile view can be used as a screening tool for potential IFI.