• Journal of the Korean Society for Nondestructive Testing
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• v.27 no.5
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• pp.383-392
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• 2007

In this paper, we study the prediction of depth and width of a defect in steam generator tube in nuclear power plant using neural network. To this end, we first generate eddy current testing (ECT) signals for 4 defect patterns of SG tube: I-In type, I-Out type, V-In type, and V-Out type. In particular, we generate 400 ECT signals for various widths and depths for each defect type by the numerical analysis program based on finite element modeling. From those generated ECT signals, we extract new feature vectors for the prediction of defect size, which include the angle between the two points where the maximum impedance and half the maximum impedance are achieved. Using the extracted feature vector, multi-layer perceptron with one hidden layer is used to predict the size of defects. Through the computer simulation study, it is shown that the proposed method achieves decent prediction performance in terms of maximum error and mean absolute percentage error (MAPE).

• Proceedings of the Korean Society of Embryo Transfer Conference
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• 2004.10a
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• pp.88-88
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• 2004

• Journal of Korean Neurosurgical Society
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• v.66 no.4
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• pp.393-399
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• 2023

Objective : Chiari II malformation (CM II) is still the main cause of severe morbidity and mortality in children with open neural tube defects (ONTDs). The goal of this study was to validate a CM II model in late-stage chick embryos with surgically induced ONTDs. Methods : To make the chick embryo model of ONTD, their neural tubes were opened for a length of 5-6 somites at the thoracic level in Hamburger and Hamilton stage 18 chick embryos (n=150). They were reincubated in ovo up to a total age of 17-21 days. A total of 19 embryos survived and were assigned to either the postoperative day (POD) 14-15 group (n=6) or the POD 17-18 group (n=13). Magnetic resonance imaging (MRI) and histopathologic findings of embryo heads with spinal ONTDs were compared with age-matched normal chick embryos. Results : The chick embryos with ONTDs demonstrated definite and constant structural changes, such as downward displacement of the cerebellum to just above the foramen magnum and narrow and small cerebrospinal fluid spaces in the crowded small posterior fossa. These morphologic features were more prominent in the POD 17-18 group than in the POD 14-15 group. Conclusion : This is the first description of CM II with spinal ONTD in a late-stage chick embryo model with MRI and histopathological analysis. The morphological changes of the posterior fossa in this study mimic those of CM II associated with spinal ONTD in humans. This model will facilitate investigation of the pathogenesis of CM II.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.1
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• pp.13-19
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• 2010

In this paper, we study a new estimation system for the prediction of steam generator tube defects. In the previous research works, defect size estimators were independently designed for each defect types in order to estimate the defect size. As a result, the structure of estimation system is rather complex and the estimation performance gets worse if the classification performance is degraded for some reason. This paper studies a new estimation system that does not require the classification of defect types. Although the previous works are expected to achieve much better estimation performance than the proposed system since it uses the estimator specialized in each defect, the performance difference is not so large. Therefore, it is expected that the proposed estimator can be effectively used for the case where the defect type classification is imperfect.

• Journal of the Korean Society for Nondestructive Testing
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• v.29 no.1
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• pp.27-35
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• 2009

In this paper, we study the classification of steam generator tube defects using an improved feature extraction. We consider 4 axisymmetric defect patterns of tube: I-In type, I-Out type, V-In type, and V-Out type. Through numerical analysis program based on finite element modeling, 400 ECT signals are generated by varying width and depth of each defect type. From those generated ECT signals, we propose new feature vectors that include an angle between the two points where the Maximum impedance and half the Maximum impedance, and angles between Maximum impedance point and 10%, 20%, 30%, 40% of Maximum impedance points. Also, multi-layer perceptron with one hidden layer is used to classify the defect patterns. Through the computer simulation study, it is shown that the proposed method achieves an improved defect classification performance in terms of Maximum Error and mean square Error.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.24 no.2
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• pp.238-243
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• 2021

Caudal regression syndrome (CRS) is a rare neural tube defect that affects the terminal spinal segment, manifesting as neurological deficits and structural anomalies in the lower body. We report a case of a 31-month-old boy presenting with constipation who had long been considered to have functional constipation but was finally confirmed to have CRS. Small, flat buttocks with bilateral buttock dimples and a short intergluteal cleft were identified on close examination. Plain radiographs of the abdomen, retrospectively reviewed, revealed the absence of the distal sacrum and the coccyx. During the 5-year follow-up period, we could find his long-term clinical course showing bowel and bladder dysfunction without progressive neurologic deficits. We present this case to highlight the fact that a precise physical examination, along with a close evaluation of plain radiographs encompassing the sacrum, is necessary with a strong suspicion of spinal dysraphism when confronting a child with chronic constipation despite the absence of neurologic deficits or gross structural anomalies.

• Journal of Veterinary Clinics
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• v.26 no.5
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• pp.467-471
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• 2009

This report describes Neural Tube Defects (NTDs) with Abdominal Wall Defects (AWDs) on the sibling of Yorkshire terriers. The NTDs and AWDs are rare serious congenital defects. The NTDs are neurulation abnormality that results from to failed transformation of the neurual tube by the incomplete closure of the embryonic neural plate. These dysraphic states range form mild to severe according to developmental malformation that include fusion defects of skull (crania bifida; CB) and fusion defects of vertebrae (spina bifida; SB). The AWDs are genetic defects that results from to failed formation of abdominal wall and cavity. These dysraphic states are omphalocele and gastroschisis. The 12-month dam was delivered by caesarian section and 4 littermate had obvious malformations. One male dead stillbirth fetus (L1) was revealed the extruded abdominal viscera, omphalocele. One female fetus (L2) was died within 1 hour after birth with defects of abdominal muscle upper umbilicus, gastroschisis. 3rd fetus (L3) was died within 36 hours after parturition and revealed a copious dermal and vertebral defects on the midline thorax, upper SB asperta. 4th fetus (L4) is still growing well now at 6 months but at the 2 week age, appears hairy nevus on the frontal cranium and dorsal thoracic portion. The radiograph of L1 and L2 are shown decrease bony density of calvarium and L3 was shown defect of spinose processes of the T9-T13. On our knowledge, this is first report of the SB and CB in Yorkshire terrier. And also sibling of NTDs with AWDs that has not previously been reported in the dog.

• Journal of Korean Neurosurgical Society
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• v.64 no.3
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• pp.386-405
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• 2021

Recent advancements in basic research on the process of secondary neurulation and increased clinical experience with caudal spinal anomalies with associated abnormalities in the surrounding and distal structures shed light on further understanding of the pathoembryogenesis of the lesions and led to the new classification of these dysraphic entities. We summarized the changing concepts of lesions developed from the disordered secondary neurulation shown during the last decade. In addition, we suggested our new pathoembryogenetic explanations for a few entities based on the literature and the data from our previous animal research. Disordered secondary neurulation at each phase of development may cause corresponding lesions, such as failed junction with the primary neural tube (junctional neural tube defect and segmental spinal dysgenesis), dysgenesis or duplication of the caudal cell mass associated with disturbed activity of caudal mesenchymal tissue (caudal agenesis and caudal duplication syndrome), failed ingression of the primitive streak to the caudal cell mass (myelomeningocele), focal limited dorsal neuro-cutaneous nondisjunction (limited dorsal myeloschisis and congenital dermal sinus), neuro-mesenchymal adhesion (lumbosacral lipomatous malformation), and regression failure spectrum of the medullary cord (thickened filum and filar cyst, low-lying conus, retained medullary cord, terminal myelocele and terminal myelocystocele). It seems that almost every anomalous entity of the primary neural tube may occur in the area of secondary neurulation. Furthermore, the close association with the activity of caudal mesenchymal tissue in secondary neurulation involves a wider range of surrounding structures than in primary neurulation. Although the majority of the data are from animals, not from humans and many theories are still conjectural, these changing concepts of normal and disordered secondary neurulation will provoke further advancements in our management strategies as well as in the pathoembryogenetic understanding of anomalous lesions in this area.

• Nutrition Research and Practice
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• v.7 no.4
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• pp.315-325
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• 2013

We evaluated folate status of child-bearing age women diagnosed with abnormal pap smear in the US post-folic acid (FA) fortification era and assessed the determinants of NTD-protective and supra-physiologic (SP) concentrations of folate. The distribution of 843 women according to NTD-protective concentrations of RBC folate, plasma folate and SP concentrations of plasma folate were tested in relation to demographic and life-style factors. Logistic regression models specified NTD-protective concentrations of RBC and plasma folate or SP concentrations of plasma folate as dependent variables and demographic and life-style factors as independent predictors of interest. More than 82% reached NTD-protective concentrations of RBC and plasma folate and ~30% reached SP concentrations of plasma folate. FA supplement use was associated with having SP concentrations of plasma folate rather than NTD-protective concentrations of folate. African American (AA) women and smokers were significantly less likely to achieve NTD-protective concentrations of RBC and plasma folate. A large majority of women reached NTD-protective concentrations of folate with the current level of FA fortification without using supplementary FA. Therefore, the remaining disparities in AA women and in smokers should be addressed by targeted individual improvements in folate intake.

• Toxicological Research
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• v.17
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• pp.11-16
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• 2001

The development of the central nervous system is a continuous process during the embryonic and fetal periods. For a better understanding of congenital anomalies of central nervous system, three major events of normal development, i.e., neurulation (3 to 4 weeks), brain vesicle formation (4 to 7 weeks) and mantle formation (over 8 weeks) should be kept in mind. The first category of anomalies is neural tube defect. Neural tube defects encompass all the anomalies arise in completion of neurulation. The second category of central nervous system anomalies is disorders of brain vesicle formation. This is anomaly that applies for "the face predicts the brain". Holoprosencephaly covers a spectrum of anomalies of intracranial and midfacial development which result from incomplete development and septation of midline structures within the forebrain or prosencephalon. The last category of central nervous system malformation is disorders involving the process of mantle formation. In the human, neurons are generated in two bursts, the first from 8 to 10 weeks and next from 12 to 14 weeks. By 16 weeks, most of the neurons have been generated and have started their migration into the cortex. Mechanism of migration disorders are multifactorial. Abnormal migration into the cortex, abnormal neurons, faulty neural growth within the cortex, unstable pial-glial border, degeneration of neurons, neural death by exogenous factors are some of the proposed mechanism. Agyria-pachygyria are characterized by a four-layerd cortex. Polymicrogyria is gyri that are too numerous and too small, and is morphologically heterogeneous. Cortical dysplasia is characterized by the presence Q[ abnormal neurons and glia arranged abnormally in focal areas of the cerebral cortex. Neuroglial malformative lesions associated with medically intractable epilepsy are hamartia or hamartoma, focal cortical dysplasia and microdysgenesis.ysgenesis.