• 대한의용생체공학회:의공학회지
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• 제23권1호
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• pp.39-47
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• 2002

본 연구의 목적은 선형 변환을 이용한 레지스트레이션의 정확도를 높이는데 있다. 서로 다른 개인간의 뇌영상을 비교분석하기 위해서는 공통된 좌표계로 각 영상을 변환하는 작업이 필요하다 정확한 변환을 위해서는 전체적인 뇌영상의 매치와 국소적 영역의 매치가 모두 중요하다 일반적으로 상호정보를 이용한 레지스트레이션은 전체적인 뇌영상을 매치시키는데 유리하다. 그러나 관심영역에 대한 매치는 특징기반 레지스트레이션 방법이 더 유리하다. 본 논문에서 제시하는 통합 레지스트레이션은 특징정보와 더불어 복셀기반의 상호정보를 함께 사용하였다. 이러한 접근 방법은 정신분열증을 판단하는 기준으로 많이 사용되는 뇌량을 포함하는 뇌의 중심부분의 매칭에 유리함을 실험을 통해 확인하였다 상호정보만을 사용하는 복셀기반 레지스트레이션이나 탈라이락 좌표계를 이용한 정규화에 비해 본 연구의 통합 레지스트레이션은 전체적 뇌영상 뿐만 아니라 관심 영역에서의 레지스트레이션 오차가 더 작았다.

• 한국콘텐츠학회논문지
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• 제21권1호
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• pp.311-320
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• 2021

현재 국내 국·공립 중등교사가 되기 위한 유일한 등용문은 중등교원 임용시험이며 2014학년도 개정 이후 임용시험의 모든 문항이 서답형으로 전환되었기 때문에 더 완성도 높고 정확하고 견고한 답안 작성이 요구된다. 재인기억을 측정하는 선택형 문항과 비교하면 회상기억을 측정하는 서답형 문항의 경우 정보 인출을 위해 더 많은 인지적 노력이 요구된다. 이 때문에 지속적인 암기 및 인출 연습이 필요하지만 이를 수행할 수 있는 학습 도구가 충분하지 않다. 이러한 맥락에서 본고는 중등영어교사 임용시험 준비용 모바일 어플인 ONE PASS를 구현하였다. 본 어플에서는 특히 인지작용의 근간이 되는 뇌의 작용기제를 반영하여 학습용 콘텐츠를 구현하였으며 학습계획 설정 및 동기측정, 마인드맵, 브레인스토밍, 기출문제 등 다양한 기능을 구안하였다. 본 연구는 학습용 어플 콘텐츠 개발 관련 연구에 이바지함과 동시에 임용시험 수험자들에게 조금이나마 도움이 될 수 있기를 기대한다.

• Investigative Magnetic Resonance Imaging
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• 제23권4호
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• pp.328-340
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• 2019

Purpose: To generate phase images with free of motion-induced artifact and susceptibility-induced distortion using 3D radial ultrashort TE (UTE) MRI. Materials and Methods: The field map was theoretically derived by solving Laplace's equation with appropriate boundary conditions, and used to simulate the image distortion in conventional spin-warp MRI. Manufacturer's 3D radial imaging sequence was modified to acquire maximum number of radial spokes in a given time, by removing the spoiler gradient and sampling during both rampup and rampdown gradient. Spoke direction randomly jumps so that a readout gradient acts as a spoiling gradient for the previous spoke. The custom raw data was reconstructed using a homemade image reconstruction software, which is programmed using Python language. The method was applied to a phantom and in-vivo human brain and abdomen. The performance of UTE was compared with 3D GRE for phase mapping. Local phase mapping was compared with T₂* mapping using UTE. Results: The phase map using UTE mimics true field-map, which was theoretically calculated, while that using 3D GRE revealed both motion-induced artifact and geometric distortion. Motion-free imaging is particularly crucial for application of phase mapping for abdomen MRI, which typically requires multiple breathold acquisitions. The air pockets, which are caught within the digestive pathway, induce spatially varying and large background field. T₂* map, that was calculated using UTE data, suffers from non-uniform T₂* value due to this background field, while does not appear in the local phase map of UTE data. Conclusion: Phase map generated using UTE mimicked the true field map even when non-zero susceptibility objects were present. Phase map generated by 3D GRE did not accurately mimic the true field map when non-zero susceptibility objects were present due to the significant field distortion as theoretically calculated. Nonetheless, UTE allows for phase maps to be free of susceptibility-induced distortion without the use of any post-processing protocols.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1997년도 춘계학술대회
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• pp.362-365
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• 1997

To visualize electrical activities in the cerebral cortex, we develop the 3D topographic mapping system based on PC. For this work, we utilize OpenGL tool and an optimized interpolation method known as 3D barycentric algotithm, which has a little computational complexity. OpenGL processes the 3D coordinates, and 3D barycentric algotithm interpolates to get overall EEGs with EEGs measured from finite electrodes on 3D. To prove validity of this algorithm on the PC-based system, we developped Windows-based 3D topographic mapping program using the Barycentric algorithm. The result showed that the performance of this system is comparable to that of workstation in terms of speed and precision. Also, the result of clinical test was the same as that of a EEG technician's analysis.

• Journal of Welding and Joining
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• 제17권5호
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• pp.40-46
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• 1999

The sensors employed in the robotic are welding system must detect the changes in weld characteristics and produce the output that is in some way related to the change being detected. Such adaptive systems, which synchronise the robot arm and eyes using a primitive brain will form the basis for the development of robotic GMA(Gas Metal Arc) welding which increasingly higher levels of artificial intelligence. The objective of this paper is to realize the mapping characteristics of bead height through learning. After learning, the neural estimation can estimate the bead height desired from the learning mapping characteristic. The design parameters of the neural network estimator(the number of hidden layers and the number of nodes in a layer) are chosen from an estimation error analysis. A series of bead of bead-on-plate GMA welding experiments was carried out in order to verify the performance of the neural network estimator. The experimental results show that the proposed neural network estimator can predict the bead height with reasonable accuracy and guarantee the uniform weld quality.

• 한국자기공명학회논문지
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• 제1권1호
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• pp.7-20
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• 1997

The mapping of the spin-spin relaxation time T2 in pixed-by-pixel was suggested as a quantitative diagnostic tool in medicine. Although the CPMG pulse sequence has been known to be the best pulse sequence for T2 measurement in physics NMR, the supplied pulse sequence by the manufacture of MRI system was able to obtain the maximum of 4 CPMG images. Eight or more images with different echo time TEs are required to construct a reliable T2 map, so that two or more acquisitions were required, which easily took more than 10 minutes. 4-echo CPMG imaging pulse sequence was modified to generate the maximum of 8 MR images with evenly spaced echo time TEs. In human MR imaging, since patients tend to move at least several pixels between the different acquisitions, 8-echo CPMG imaging sequence reduces the acquisition time and may remove any misregistration of each pixel's signal for the fitting T2. The resultant T2 maps using the theoretically simulated images and using the MR images of the human brain suggested that 8 echo CPMG sequence with short echo spacing such as 17∼20 msec can give the reliable T2 map.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• 제18권1호
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• pp.31-37
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• 2007

Objectives : A voxel based investigation of cerebral blood flow was conducted to identify functional differences during resting state between children with early-onset schizophrenia and normal controls. Methods : 19 children and adolescents with early-onset schizophrenia(8 boys and 11 girls, mean age $14.0{\pm}1.7$ years old) and 17 comparison children(13 boys and 4 girls, mean age $11.0{\pm}1.9$ years old) were examined by HMPAO-SPECT. The SPECT images were compared using statistical parametric mapping analyses, controlling for age and sex. Results : Increased cerebral blood flow in left medial and inferior frontal gyrus, right superior and middle frontal gyrus, both inferior temporal gyrus, and right cerebellar tonsil was found in children and adolescents with early-onset schizophrenia compared to control subjects. In addition, decreased cerebral blood flow in right thalamus, left posterior cingulate gyrus, right anterior cingulate gyrus and relatively wide areas from left medical frontal gyrus to superior parietal lobule were found in children and adolescents with early-onset schizophrenia compared to control subjects. Conclusion : The results of the current study provide additional evidences for brain areas involving the onset of schizophrenia in early age.

• Investigative Magnetic Resonance Imaging
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• 제4권1호
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• pp.14-19
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• 2000

목적 : 뇌열환자에서 기능적 자기공명영상과 경두부 자기자극을 이용하여 뇌기능을 지도화하고자하였다. 대상 및 방법: 자기공명영상에서 우측 대뇌반구에 뇌열 소견이 있으며 좌측 편측부전마비를 보인 28세 남자환자를 대상으로 기능적 자기공명영상과 경두부 자기자극을 시행하였다. 임상적으로 좌측 손의 운동기능은 감소되어 있었고, 우측 손의 운동기능은 정상범주에 속하였다. 뇌기능적 자기공명영상은 EPI 기법을 이용하였고 운동자극은 1-2 Hz의 주기로 손가락을 아래위로 구부리게 하는 운동을 시행하였고 15초의 휴식기와 15초의 운동기를 반복하여 절편당 60 개의 영상을 획득하였다. 두부자기자극은 지름 90mm의 원형 자성자극기를 이용하여 maximal out-put의 80%로 자극하여 양측 단무지 외 전근에서 유발된 운동유발전위의 잠시와 진폭을 구하였다. 결과: 기능적 자기공명영상을 시행한 결과 정상적인 우측손의 운동자극시에 좌측 운동피질이 활성화되었고 좌측손의 운동자극시에는 좌측운동피질, 좌측 부가운동영역, 그리고 자측 전운동영역에 활성화소견이 나타났다. 두부자기자극에서는 우측 대뇌반구에서는 한군데에서도 운동유발 전위가 발생되지 않았다. 좌측 대뇌반구에서는 5군데에서 운동유발전위가 유발되었으며 모두 양측 단무지 외 전근에서 운동유발전위가 유발되었다. 양손에서 운동유발전위의 잠시 , 진폭 모양이 유사하였다. 결론: 뇌열환자의 손운동기능의 피지도화는 기능적 자기공명영상과 두부자기자극을 이용하여 성공적으로 시행할 수 있었다. 뇌열환자의 동측 운동경로는 동일한 운동피질로부터 기원한 동측피질척수로에 의한 것으로 추정된다.

• Korean Journal of Radiology
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• 제20권4호
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• pp.662-670
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• 2019

Objective: A developmental venous anomaly (DVA) is a vascular malformation of ambiguous clinical significance. We aimed to quantify the susceptibility of draining veins (χ_vein) in DVA and determine its significance with respect to oxygen metabolism using quantitative susceptibility mapping (QSM). Materials and Methods: Brain magnetic resonance imaging of 27 consecutive patients with incidentally detected DVAs were retrospectively reviewed. Based on the presence of abnormal hyperintensity on T2-weighted images (T2WI) in the brain parenchyma adjacent to DVA, the patients were grouped into edema (E+, n = 9) and non-edema (E-, n = 18) groups. A 3T MR scanner was used to obtain fully flow-compensated gradient echo images for susceptibility-weighted imaging with source images used for QSM processing. The χ_vein was measured semi-automatically using QSM. The normalized χ_vein was also estimated. Clinical and MR measurements were compared between the E+ and E- groups using Student's t-test or Mann-Whitney U test. Correlations between the χ_vein and area of hyperintensity on T2WI and between χ_vein and diameter of the collecting veins were assessed. The correlation coefficient was also calculated using normalized veins. Results: The DVAs of the E+ group had significantly higher χ_vein (196.5 ± 27.9 vs. 167.7 ± 33.6, p = 0.036) and larger diameter of the draining veins (p = 0.006), and patients were older (p = 0.006) than those in the E- group. The χ_vein was also linearly correlated with the hyperintense area on T2WI (r = 0.633, 95% confidence interval 0.333-0.817, p < 0.001). Conclusion: DVAs with abnormal hyperintensity on T2WI have higher susceptibility values for draining veins, indicating an increased oxygen extraction fraction that might be associated with venous congestion.

• 대한한의학회지
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• 제27권2호
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• pp.36-43
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• 2006

Objectives : Acupuncture has been widely applied to rehabilitation after stroke by Oriental medical doctors in Korea. It has been reported that acupuncture increased cerebral blood supply and stimulated the functional activity of brain nerve cells. In addition, a correlation between activation of specific areas of brain cortices and corresponding acupuncture stimulation at the therapeutic points had been well illustrated. rill now, however, there were few studies which evaluated a correlation between activation of specific areas of brain and frequently-used acupuncture therapy for stroke, such as LI4-LI11 electro-acupuncture (EA) for paresis after stroke. This study was undertaken to evaluate the effect of LI4-LI11 EA on regional cerebral blood flow (rCBF) in normal volunteers using Single Photon Emission Computed Tomography (SPECT). Methods : In the resting state, $^{99m}Tc-ECD$ brain SPECT scans were performed on 10 normal volunteers (8 males, 2 females, mean age $25.6{\pm}2.3$years; age range from 24 to 31 years). 7 days after the resting examination, 15 minutes of electro-acupuncture were applied at LI 4 and LI 11 on the right side of the subjects. Immediately after LI4-LI11 EA, the second SPECT images were obtained in the same manner as the resting state. Significant increases and decreases of regional cerebral blood flow after LI4-LI11 EA were estimated by comparing their SPECT images with those of the resting state using paired t statistics at every voxel, which were analyzed by Statistical parametric mapping with a threshold of p=0.001, uncorrected (extent threshold: k=100 voxels). Results : EA applied at right LI4-LI11 increased rCBF in right frontopolar area (Brodmann area 10) and left middle frontal area (Brodmann area 46). Interestingly, all the areas showing increased rCBF corresponded to the territories of both anterior cerebral arteries. However, LI4-11 EA decreased rCBF in the left occipital lobe (peristriate area, Brodmann area 19). Conclusions : The results demonstrated a correlation between LI4-11 EA and rCBF increase in the frontal lobes. It is also suggested that there may be a correlation between LI meridian and the territory of the anterior cerebral arterties.