• The Korean Journal of Nuclear Medicine
• /
• v.30 no.4
• /
• pp.463-468
• /
• 1996

본 연구는 간질 병소의 국소화에 있어 발작기 및 발작간 뇌스캔의 정확도를 알아보고 발작기 뇌 스캔에서 나타나는 간질 확산이 정확한 간질 병소를 국소화 하는데 어떠한 영향을 미치는가에 대하여 알아보고자 하였다. 15명의 복잡 부분 발작 환자를 대상으로 하였으며, 간질 병소의 최종적인 국소화는 두피 및 발작 뇌파, 피질 뇌파, 자기 공명 영상, 임상양상 및 병리 소견을 종합한 근거로 하였다. 발작기 뇌스캔은 뇌파상 발작 중 또는 환자가 aura를 호소할 때 Tc-99m HMPAO 20mCi(740 MBq)를 정맥주입후 시행하였으며 발작간 뇌스캔은 발작기 뇌스캔 후 3일 이내 임상적으로 발작 증상이 없는 기간에 시행하였다. 간질 병소는 우측 측두엽이 8예, 좌측 측두엽이 6예, 측두엽 이외의 기원이 1예 였다. 발작기 뇌스캔상, 모두 11예(73.3 %)에서 단발성 또는 다발성 섭취 증가가 간질 병소 및 간질확산 부위에서 관찰되었으며, 간질 병소에만 국한된 섭취 증가는 4예(26.7%)에 불과 하였다. 발작간 뇌스캔에는 모두 11예(73.3 %)에서 간질 병소에만 섭취가 감소되었다. 자기 공명 영상에서는 8예(53.3 %)에서 hippocampal sclerosis를 포함한 간질 병소가 확인되었다. 본 연구로 복잡 부분 발작 환자에서, 간질 확산이 발작기 뇌 스캔 중 자주 관찰됨을 알 수 있었으며, 이러한 간질 확산에 따른 다발성 방사능 섭취가 발작기 뇌스캔상, 간질 병소의 국소화에있어 한계가 있음을 결론 내릴 수 있었다.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.41 no.4
• /
• pp.322-327
• /
• 2014

Regional odontodysplasia (RO) is a rare and nonhereditary dental malformation. It is a dental alteration of unknown etiology, involving both mesodermal and ectodermal dental components, which is characterized by clinical, radiographic, and histologic features. The maxilla is more often involved than the mandible (especially the left side), and there is no racial predilection, but females are affected twice as often as males. The affected teeth are clinically hypoplastic and hypocalcified, presenting a "ghost-like" appearance radiographically. The present case features a male patient aged 4 years and 6 months who was diagnosed with regional odontodysplasia in the maxilla on the right side, confirmed by clinical and radiographic examination, with a follow up of 5 years. Since teeth affected by RO have a poor prognosis due to the fragile tooth surface and open apices, the long-term treatment strategy depends on periodic clinical and radiological observations.

• The Korean Journal of Nuclear Medicine
• /
• v.33 no.3
• /
• pp.262-272
• /
• 1999

Purpose: Interictal F-18-fluorodeoxyglucose (FDG) PET and ictal Tc-99m-HMPAO SPECT are found to be useful in localizing epileptogenic zones in neocortical lateral temporal or frontal lobe epilepsy. We investigated whether interictal F-18-FDG PET or ictal Tc-99m-HMPAO SPECT was useful to find epileptogenic Bones in occipital lobe epilepsy (OLE). Materials and Methods: We reviewed patterns of hypometabolism in interictal F-18-FDG PET and of hyperperfusion in ictal Tc-99m-HMPAO SPECT in 17 OLE patients (mean age=$27{\pm}6.8$ year, M:F= 10:7, injection time= $30{\pm}17$ sec). OLE was diagnosed based on invasive electroencephalography (EEG) study, surgery and post-surgical outcome (Engel class I in all for average 14 months). Results: Epileptogenic zones were correctly localized in 9 (60%) out of 15 patients by interictal F-18-FDG PET. Epiletogenic hemispheres were correctly lateralized in 14 patients (93%). By ictal Tc-99m-HMPAO SPECT, epileptogenic hemispheres were correctly lateralized in 13 patients (76%), but localization was possible only in 3 patients (18%). Among patients who showed no abnormality with MR imaging and no correct localization with ictal Tc-99m-HMPAO SPECT, interictal F-18-FDG PET was helpful in 2 patients. Conclusion: Ictal Tc-99m-HMPAO SPECT was helpful in lateralization but not in localization in OLE. Interictal F-18-FDG PET was helpful for localization of epileptogenic zones even in patients with ambiguous MR or ictal SPECT findings.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.36 no.1
• /
• pp.96-101
• /
• 2009

Regional odontodysplasia(ROD) is relatively rare localized developmental anomaly of tooth formation in which hard tissue is affected. The maxilla is typically affected than the mandible, and especially the maxillary left quadrant is the most commonly involved. Females are affected twice as often as males, and there is no association with race. Its etiology remains undetermined, but local circulatory disorders, somatic mutations, virus infections, local trauma, hyperpyrexia, irradiation, metabolic disturbances, and hereditary transmission are considered as possible etiologic factors. The affected teeth are likely to be small, hypoplastic, brown, and grooved. Eruption failure or delay is frequently seen as well as abscess or fistulae formation in absence of caries. Radiographically, there is a lack of contrast between the enamel and dentin, both of which are less radiopaque than unaffected counterparts. Moreover, enamel and dentin layers are thin, giving the teeth a “ghost-like appearance”. The pulp chambers and canals are large, the roots seem like to be short and indistinct. A 2-year-3-month old boy came to the department of pediatric dentistry, Yonsei University, with the chief complaint of delayed eruption and abnormal tooth shape on the lower left quadrant. He was diagnosed as regional odontodysplasia based on the clinical and radiographic findings.

• Journal of the Korean Institute of Telematics and Electronics S
• /
• v.36S no.12
• /
• pp.51-57
• /
• 1999

In this paper, an adaptive thresholding of the nonuniformly contrasted images is proposed through using the contrast pre-enhancement of the local regions and the bilinear interpolation between the local threshold values. The nonuniformly contrasted image is decomposed into 9${\times}$9 sized local regions, and the contrast is enhanced by intensifying the gray level difference of each low contrasted or blurred region. Optimal threshold values are obtained by iterative method from the gray level distribution of each contrast-enhanced local region. Discontinuities are reduced at the region of interest or at the characters by using bilinear interpolation between the neighboring threshold surfaces. Character recognition experiments are conducted using backpropagation neural network on the characters extracted from the nonuniformly contrasted document, PCB, and wafer images binarized through using the proposed thresholding and the conventional thresholding methods, and the results prove the relative effectiveness of the proposed scheme.

• Journal of Korean Ophthalmic Optics Society
• /
• v.19 no.2
• /
• pp.247-252
• /
• 2014

Purpose: This study was to investigate the properties and the location of neural reorganization following eccentric viewing training. Methods: 14 subjects with normal vision took part in eccentric viewing training. The measurements of the light sensitivity and multifocal electroretinogram were performed before and after the training. Results: The measurements of the light sensitivity and multifocal electroretinogram for pre-eccentric viewing training and post-eccentric viewing training showed the significant difference (p<0.047 and p<0.028, respectively). Conclusions: The retinal outer plexiform layer is unable to regenerate. However, the neural reorganization in the retinal outer plexiform layer is able to take place following eccentric viewing training.

• The Korean Journal of Applied Statistics
• /
• v.31 no.6
• /
• pp.707-719
• /
• 2018

Various time series representation methods have been proposed for efficient time series clustering and classification. Lin et al. (DMKD, 15, 107-144, 2007) proposed a symbolic aggregate approximation (SAX) method based on symbolic representations after approximating the original time series using piecewise local mean. The performance of SAX therefore depends heavily on how well the piecewise local averages approximate original time series features. SAX equally divides the entire series into an arbitrary number of segments; however, it is not sufficient to capture key features from complex, large-scale time series data. Therefore, this paper considers data-adaptive local constant approximation of the time series using the unbalanced Haar wavelet transformation. The proposed method is shown to outperforms SAX in many real-world data applications.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2008.11a
• /
• pp.301-302
• /
• 2008

• Proceedings of the IEEK Conference
• /
• 2000.06e
• /
• pp.131-133
• /
• 2000

In this paper, we proposed a new method for localizing the independent sources generating the observed EEG based on independent component analysis (ICA). The performance of the algorithm was tested through computer simulations.

• 대한핵의학회:학술대회논문집
• /
• 1996.05a
• /
• pp.177-177
• /
• 1996