• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.235-238
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• 1997

The Graphical User Interface (GUI) software is developed for 0.3 Tesla Permanent Magnet Resonance Imaging (MRI) system and the state of art of designing GUI system is discussed in this paper. The Object-Oriented concepts are applied for designing GUI software utilizing Interbase ODBC Database layer. Also, Multimedia concepts such as voice, sound and music are integrated in GUI system to enhance the efficiency of MRI operation.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2001.02a
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• pp.48-49
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• 2001

Cryogenic technology is one of the key technologies for fusion reactor equipped with superconducting coil for plasma confinement. The KSTAR(Korea Superconducting Tokamak Advanced Research)Project is in progress since 1996. Major parameters of the KSTAR tokamak are : major radius 1.8m, minor radius 0.5m, toroidal field 3.5 Tesla and plasma current 2MA with a strongly shaped plasma cross-section and double -null diverter. Considering practical engineering constraints, the KSTAR device is designed for a pulse length of 300 sec in up-graded operation mode but in the initial configuration would provide a pulse length of 20 sec provided by the poloidal coil system in base-line operation mode. The cryogenic system is composed as follows : cold box, helium compressor system, distribution box, helium gas buffer tank, helium gas purifying system, gas recovery system, liquid helium storage dewar, current lead box, current bus line and liquid nitrogen storage tank.

• Proceedings of the KOSOMBE Conference
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• v.1998 no.11
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• pp.307-308
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• 1998

In this paper, we describe a field measurement technique using multiple gradient echo method. For this purpose, 3 differential phase map is used between two images obtained in a single scan. The phase map is further processed to unfold phase folding (2n $\pi$). The inhomogeneity map is used to correct image distortion along readout gradient direction. Some experimental results obtained at 1.0 Tesla whole body MR system are shown with the proposed technique.

• Proceedings of the KOSOMBE Conference
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• v.1996 no.05
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• pp.108-110
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• 1996

Open MRI is a new concept in clinical application of the MRI such as interventional study. Receiving RF coils used in the open MRI must have open structures to insure convenient manipulations fur the patient. In this paper, we presented experimental study fur open head coil suitable to 0.3 Tesla vertical field MRI system with its experimental results.

• Journal of the Korean Society of Radiology
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• v.12 no.4
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• pp.481-489
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• 2018

In MRI examination, when irradiating the human body with RF Pulse to acquire images, the portion of the irradiated RF Pulse energy is absorded into the human body, and this will affect the temperature of the human body. If a metal is inserted into the human body even if the same RF Pulse energy is applied, the SAR value increases and the body temperature changes due to the increase in the electromagnetic wave conductivity of the metal. So we measure and compared with the change in the SAR and temperature in the implant material of the dental implant in Brain MRI examinations. Experiments were performed on a human head model using a 64MHz and 128 MHz RF Pulse frequency generated by a 3.0 Tesla MRI apparatus. And then changed material of dental implants to Titanium and $Al_2O_3$. Using the XFDTD program, the changes in SAR and body temperature around the head were examined. When with Titanium the SAR value and temperature of Brain increased, but with $Al_2O_3$ showed lower SAR and temperature as compared with Titanium. The dental implants were low in SAR and temperature of the head in $Al_2O_3$, which are electrical insulators with low electrical conductivity, compared to Titanium, which is an electrical conductor. It is necessary to study the biologic effect of patient with brain MRI when titanium dental implant material is inserted in the future. Because the maximum value of SAR is much higher than the limit when dental implant material is Titanium. In addition, it is necessary to use an implant of $Al_2O_3$ material to reduce the SAR value and temperature of the Brain in Brain MRI examination.

• Progress in Medical Physics
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• v.20 no.4
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• pp.244-252
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• 2009

The purpose of this study is to compensate for susceptibility and a ferromagnetic body artifact using CFA and TGV on MR Imaging. A total of 30 patients (15 men and 15 women, mean age: 45 years) were performed on head and neck diseases. MR Unit used a 1.5T superconducting magnet (GE medical system, High Density). This study have investigated by changing with CFA and TGV (70, 90, 110, 130, 150) searching for compensation values about susceptibility and a ferromagnetic body artifact in 60 kg standards of body weight (p<0.05). As a quality results, Image qualities were obtained at different score from CFA and TGV (70, 90, 110, 130, $150=3.23{\pm}0.35$, $4.31{\pm}0.02$ $4.23{\pm}0.21$, $5.12{\pm}0.25$, $7.13{\pm}0.72$, $8.31{\pm}0.01$, $5.21{\pm}0.15$, $6.14{\pm}0.08$, $5.23{\pm}0.72$, $5.91{\pm}0.06$, p<0.05). Absolute CNRs (TG, CNRpre, CNRpost) were acquired with (70:$-1.44{\pm}0.11$, $-2.7{\pm}0.04$, 90:$-2.18{\pm}0.42$, $-4.41{\pm}0.43$, 110:$-2.89{\pm}0.43$, $-5.23{\pm}0.02$, 130:$-2.34{\pm}0.05$, $-5.26{\pm}0.01$, 150: $-2.09{\pm}0.08$, $-3.87{\pm}0.12$, p<0.05). In conclusions, this study could be compensated for metal and flow artifacts surrounding the tissues having artifact by changing CFA and TGV.

• Korean Journal of Materials Research
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• v.5 no.4
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• pp.433-444
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• 1995

BaCe$O_{3}$를 첨가하여 용융공정으로 제조한 단결정형 Y$Ba_{2}$$Cu_{3}$$O_{x}$(1-2-3) 초전도체의 온도에 대한 자화특성을 연구하였다. 고상반응법과 용융공정으로 0에서 30wt% BaCe$O_{3}$를 1-2-3 결정내에 미세 분산시켰다. 초전도체의 자화특성은 VSM(vibrating sample magnetometer)을 사용하여 77K, 60K, 40K와 20K, 2 Tesla 자장범위에서 측정하였다. BaCe$O_{3}$를 첨가하지 않은 겨우나 5wt% BaCe$O_{3}$를 첨가한 1-2-3 결정의 경우, 77K, 외부자장이 증가시 자화율 차이가 증가하는 비정상 자화특성이 관찰된다. 측정온도가 60K에서는 제2차 최대점이 나타나는 자장값이 고자장쪽으로 이동한다. 20K와 40K의 저온에서는 비정상자화특성이 2 T의 자장범위까지 관찰되지 않았다. 15wt%와 20wt% BaCe$O_{3}$첨가한 시편에서는 자장이 증가하면 자화율차이가 단순히 감소한다. Y-Ba-Cu-O의 flux pinning 기구를 BaCe$O_{3}$첨가에 의한 미세조직변화로 설명하였다.

• Korean Journal of Mineralogy and Petrology
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• v.37 no.3
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• pp.127-138
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• 2024

We report an easy, efficient method for separating monazite grains using a sequence of gold pan, tap water, disposable sieve, magnet (0.35 T), and heavy liquid. The grain size after powdering (<230 ㎛) and the separation process using a water-filled pan (tilted at 10°) and a water supply (0.1 L/sec) followed the method described in Cheong et al. (2013). Ferro-magnetic minerals were most effectively removed using a magnet with a strength of 0.35 T (Tesla), but were not para-magnetic minerals such as monazite and xenotime. The remaining light particles from the previous process were finally separated using a heavy liquid, diiodomethane (CH₂I₂; G=3.32). Our method has the advantage of effectively separating not only monazite, but also xenotime and titanite.

• Korean Journal of Radiology
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• v.2 no.2
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• pp.80-86
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• 2001

Objective: To assess the potential clinical utility of in-vivo 31P magnetic resonance spectroscopy (MRS) in patients with various malignant and benign breast lesions. Materials and Methods: Seventeen patients with untreated primary malignant breast lesions (group I), eight patients with untreated benign breast lesions (group II) and seven normal breasts (group III) were included in this study. In-vivo 31P MRS was performed using a 1.5 Tesla MR scanner. Because of the characteristics of the coil, the volume of the tumor had to exceed 12 cc (3×2×2 cm), with a superoinferior diameter at least 3 cm. Mean and standard deviations of each metabolite were calculated and metabolite ratios, such as PME/PCr, PDE/PCr, T-ATP/PCr and PCr/T-ATP were calculated and statistically analyzed. Results: Significant differences in PME were noted between groups I and III (p=0.0213), and between groups II and III (p=0.0213). The metabolite ratios which showed significant differences were PME/PCr (between groups II and III) (p=0.0201), PDE/PCr (between groups I and III, and between groups II and III) (p=0.0172), T-ATP/PCr (between groups II and III) (p=0.0287), and PCr/T-ATP (between groups II and III) (p=0.0287). There were no significant parameters between groups I and II. Conclusion: In-vivo 31P MRS is not helpful for establishing a differential diagnosis between benign and malignant breast lesions, at least with relatively large lesions greater than 3 cm in one or more dimensions.

• Journal of Veterinary Clinics
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• v.30 no.4
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• pp.320-323
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• 2013

Spinal cord infarction is becoming recognized as an important cause of acute myelopathy in cats. Although the definitive diagnosis is confirmed through postmortem histopathologic examination, MR imaging features provide valuable informations for the diagnosis of spinal cord infarction. The aim of this report is to describe MR findings of acute spinal cord infarction in two cats and to evaluate usefulness of low field MRI (0.3Tesla) as a potential diagnostic tool of acute spinal cord infarction. A cat (unknown age, neutered male mixed breed cat) was referred one day after the acute onset of non-ambulatory spastic tetraparesis and the other cat (a 9-year-old, neutered female domestic short hair cat) was presented due to the acute onset of non-ambulatory paraparesis and one day later paraplegia. The lesions of the MR images were shown on the spinal cord parenchyma over C2 to C6 in case 1 and L2 to L5 in case 2. The MR images in these two cases were characterized by focal intramedullary lesions, mainly involving grey matter which were hyperintense T2 weighted and FLAIR images and hyperintense on DWI and hypointense on ADC map. The MR findings in both cases were highly suggestive of acute spinal cord infarctions, based upon previous reported small animal cases and human cases. In conclusion, based on MR features, together with the history and clinical examination findings, MRI modality can be used as an antemortem tool for the diagnosis of acute spinal cord infarction in cats.