• Proceedings of the KIEE Conference
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• 2004.07d
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• pp.2685-2686
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• 2004

심자도(Magnetocardiography: MCG)는 심장에서 발생하는 자기신호로 크기가 수 pico Tesla에서 수 femto Tesla 정도로 지구 자기에 비하여 $10^{-6}{\sim}10^{-10}$ 정도로 매우 작기 때문에 보통 3층의 차폐 막 구조로 되어 있는 자기차폐실을 사용하여 외부 잡음을 줄인다. 그러나 자기차폐실의 비용이 크기 때문에, 자기차폐실의 비용을 줄이고 다양한 신호처리를 병행하여 신호대 잡음비를 높이고 있다. 본 논문에서는 1Giga FLOPS (FLoating point Operationals Per Second)의 부동 소숫점 연산능력을 가진 TMS320C6701을 사용하여 실시간 신호처리가 가능한 신호처리 시스템을 설계하였다. 개발된 DSP 보드는 PCI-bus 기반으로 설계하여 신호 측정 컴퓨터에 내장이 가능하도록 하였다. 프로그램과 데이터 처리를 위한 외부 메모리를 장착하였고, PCI 콘트롤러를 갖추어 PC 와의 대용량 메모리 공유가 가능하도록 하였다. 제작된 DSP 보드를 사용하여, 심자도 신호에서 실시간으로 적응 잡음 소거 및 필터링을 구현하여 신호대 잡음비의 향상을 확인할 수 있었다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.2
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• pp.237-242
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• 2019

Recently, as the public interest in autonomous cars has increased, research and technology development of related companies for the commercialization of autonomous cars have been actively carried out, and the development has progressed to a stage where they are partially but actually used. However, in March 2018, Uber and Tesla cars caused two fatal accidents, and the need for a new system is emerging. Therefore, this paper suggests a new information processing model for autonomous driving car system by supplementing the cause of recognition errors caused by the cause of death by focusing on the accident of autonomous driving car.

• Korean Journal of Radiology
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• v.19 no.6
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• pp.1007-1020
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• 2018

Objective: To compare the diagnostic performance of cardiovascular magnetic resonance (CMR) myocardial perfusion at 1.5- and 3-tesla (T) for detecting significant coronary artery disease (CAD), with invasive coronary angiography (ICA) as the reference method. Materials and Methods: We prospectively enrolled 281 patients (age $62.4{\pm}8.3$ years, 193 men) with suspected or known CAD who had undergone 1.5T or 3T CMR and ICA. Two independent radiologists interpreted perfusion defects. With ICA as the reference standard, the diagnostic performance of 1.5T and 3T CMR for identifying significant CAD (${\geq}50%$ diameter reduction of the left main and ${\geq}70%$ diameter reduction of other epicardial arteries) was determined. Results: No differences were observed in baseline characteristics or prevalence of CAD and old myocardial infarction (MI) using 1.5T (n = 135) or 3T (n = 146) systems. Sensitivity, specificity, positive and negative predictive values, and area under the receiver operating characteristic curve (AUC) for detecting significant CAD were similar between the 1.5T (84%, 64%, 74%, 76%, and 0.75 per patient and 68%, 83%, 66%, 84%, and 0.76 per vessel) and 3T (80%, 71%, 71%, 80%, and 0.76 per patient and 75%, 86%, 64%, 91%, and 0.81 per vessel) systems. In patients with multi-vessel CAD without old MI, the sensitivity, specificity, and AUC with 3T were greater than those with 1.5T on a per-vessel basis (71% vs. 36%, 92% vs. 69%, and 0.82 vs. 0.53, respectively). Conclusion: 3T CMR has similar diagnostic performance to 1.5T CMR in detecting significant CAD, except for higher diagnostic performance in patients with multi-vessel CAD without old MI.

• Investigative Magnetic Resonance Imaging
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• v.9 no.1
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• pp.24-29
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• 2005

Purpose : Instead of conventional two-dimensional (2-D) visual stimuli, three-dimensional (3-D) visual stimuli with stereoscopic vision were employed for the study of functional Magnetic Resonance Imaging (f-MRI). In this paper f-MRI with 3-D visual stimuli is investigated in comparison with f-MRI with 2-D visual stimuli. Materials and Methods : The anaglyph which generates stereoscopic vision by viewing color coded images with red-blue glasses is used for 3-D visual stimuli. Two-dimensional visual stimuli are also used for comparison. For healthy volunteers, f-MRI experiments were performed with 2-D and 3-D visual stimuli at 3.0 Tesla MRI system. Results : Occipital lobes were activated by the 3-D visual stimuli similarly as in the f-MRI with the conventional 2-D visual stimuli. The activated regions by the 3-D visual stimuli were, however, larger than those by the 2-D visual stimuli by $18\%$. Conclusion : Stereoscopic vision is the basis of the three-dimensional human perception. In this paper 3-D visual stimuli were applied using the anaglyph. Functional MRI was performed with 2-D and 3-D visual stimuli at 3.0 Tesla whole body MRI system. The occipital lobes activated by the 3-D visual stimuli appeared larger than those by the 2-D visual stimuli by about $18\%$. This is due to the more complex character of the 3-D human vision compared to 2-D vision. The f-MRI with 3-D visual stimuli may be useful in various fields using 3-D human vision such as virtual reality, 3-D display, and 3-D multimedia contents.

• Journal of radiological science and technology
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• v.30 no.3
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• pp.265-270
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• 2007

The purpose of this study was to evaluate the possibility of utilizing MT pulse at CE-TOF-MRA in patients with cerebral infarction. MRA using time-of-flight(TOF) technique with varying offset frequencies (0, 600, 1,200, and 1,800 Hz) magnetization transfer were performed in 10 patients with cerebral infarction at 3.0T MR scanner. CE-TOF-MRA and TOF-SPGR in normal vessel shown decreased SNR and increased CNR. The highest CNR in narrowing vessel shown at CE-TOF-MRA using 600 and 1,200 Hz offset frequencies. CNR in stenosis vessel increased dependent on using offset frequencies. The occlusion was clearly shown, and the highest CNR in occlusion shown at CE-TOF-MRA using 1,800 Hz offset frequencies. There was no shape variation in narrowing vessel or no visualizing vessel.

• 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.

• Proceedings of the KSMRM Conference
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• 2007.10a
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• pp.55-56
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• 2007

• Proceedings of the KSMRM Conference
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• 2001.11a
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• pp.114-114
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• 2001

목적： 열적인 방법으로 시술을 할 때 발생한 생체 조직의 온도 변화는 생체조직의 전기임피던스 변화를 야기하는데 이 전기임피던스 변화가 자기공명영상의 위상에 어떠한 영향을 미치는지를 분석하고자 하였다. 대상 및 방법： 생체조직의 전기임피던스는 조직부위에 따라 다르나 온도계수가 평균적으로 -2%/$^{\circ}C$에 이를 만큼 온도에 민감한 특성을 가지고 있다. 이러한 특성을 감안하여 유한요소법을 이용하여 자기공명영상의 위상을 계산하여 보았다. 그 결과를 토대로 0.3Tesla 자기공명영상시스템으로 팬텀을 촬영하여 자기공명영상의 위상을 구하였다.

• 대한관절경학회:학술대회논문집
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• 2009.10a
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• pp.165-169
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• 2009

연골 결손은 자체 치유 능력이 적어 그 크기가 1 cm 이상인 경우 골관절염이 발생할 수 있다. 최근에는 3-tesla MRI 등의 발전으로 인해 수술 전에 미리 연골 손상을 정확히 진단할 수 있어 연골 손상의 치료를 더욱 적극적으로 할 수 있다. 이제까지 연골 손상에 대한 수술적 치료는 세척술(lavage) 및 변연 절제술(debridement), 미세 천공술(microfracture), 자가 골연골 이식술(autologous osteochondral graft), 자가 연골 세포 이식술(autologous chondrocyte implantation, ACI), 동종 골연골 이식술(osteochondral allograft)이 있다.

• Proceedings of the KSMRM Conference
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• 2006.11a
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• pp.41-41
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• 2006