• Journal of the Korean Society of Radiology
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• v.83 no.5
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• pp.979-990
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• 2022

Biliary atresia is a progressive, idiopathic, obliterative disease of the extrahepatic biliary tree that presents with biliary obstruction in the neonatal period. It is the most common indication for liver transplantation in children. If untreated, progressive liver cirrhosis leads to death by two years of age. Nowadays, more than 90% of biliary atresia patients survive into adulthood with the development of Kasai portoenterostomy and liver transplantation technology. Early diagnosis is critical since the success rate of the Kasai portoenterostomy decreases with time. This study comprehensively reviews the recent advances in the etiology, classification, prevalence, clinical manifestations, treatment, and prognosis of biliary atresia.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.11
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• pp.157-163
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• 2019

This study determines the difference in prevalence of anemia and hemoglobin concentration between chronic obstructive pulmonary disease (COPD) and control groups in the elderly. Moreover, this study also examines the prevalence of anemia and hemoglobin concentration according to the severity of COPD in the elderly. Medical records of 8150 participants who answered the 7th National Health and Nutritional Survey conducted in 2016 were reviewed, and a total of 694 participants was included in the analysis. Participants were classified into two groups: COPD and control groups. Laboratory studies on hemoglobin, hematocrit, red blood cell concentration and prevalence of anemia were collected. Subgroup analysis was also conducted according to the severity of COPD. No significant differences were determined for the prevalence of anemia and hemoglobin concentration between both groups. Hemoglobin concentration was significantly higher in the COPD group. Although not statistically significant, there was a tendency for decrease in the prevalence of anemia and increase in the hemoglobin concentration as the severity of COPD increased. Our findings present specific data about the prevalence of anemia and hemoglobin concentration in elderly patients with COPD. Hence, we propose that occurrence of anemia in elderly patients with COPD requires further evaluation of the causes.

• Journal of radiological science and technology
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• v.32 no.1
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• pp.33-38
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• 2009

Objective : This study was conducted to determine an association between aortic calcification viewed on plain chest radiography and obstructive coronary artery disease. Method : Retrospective review of all chest radiography obtained from consecutive patients undergoing coronary angiography. Chest PA images were reviewed by technical radiologist and radiologist. Considering the presence of aortic arch calcification, images were compared with the results of coronary angiography. In addition, the size of aortic arch calcification were divided into two groups - the smaller and the larger than 10 mm. Results : Among the total 846 patients, the number of the patients with obstructive coronary artery disease is total 417 (88.3%) in males and 312 (83.4%) in females. Considering the presence of aortic arch calcification, the positive predictive value of relation between aortic arch calcification and obstructive coronary artery disease was 91.4% and the relative risk of the group with aortic arch calcification to the opposite group was 1.10. According to the size of aortic arch calcification and obstructive coronary artery disease, the positive predictive value was 91.9% and the relative risk between two groups was 1.04. Conclusions : This study shows that aortic calcification was closely associated with obstructive coronary artery disease. If the aortic calcification is notified on plain chest radiography, we strongly recommend to consult with doctor.

• Journal of the korean academy of Pediatric Dentistry
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• v.42 no.3
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• pp.233-241
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• 2015

The aim of this study was to determine the bite force and lip closing force in preschool children and to analyze the correlation between these forces by age, height and weight, respectively. Data were obtained from 98 children (56 males, 42 females) ranging from 3 to 6 years of age. The magnitude of the bite force was measured bilaterally corresponding with the 2nd primary molars using a bite force gauge, $GM10^{(R)}$ (Nagano Keiki) and the force of lip closure was measured using LIP DE $CUM^{(R)}$ (Cosmo Instruments). The averages of bite force for boys and girls were 217.69 N and 205.05 N, respectively. The relationship between bite force with age, height, and weight present significant positive correlation (p < 0.001, p < 0.001, and p < 0.001, respectively). The averages of lip closing force for boys and girls were 4.81 N and 4.07 N respectively. The relationship between lip closing force with age, height, and weight present significant positive correlation (p < 0.001, p < 0.001, and p < 0.001, respectively). No significant differences were observed between boys and girls (p > 0.05) in both forces. A significant correlation was observed between lip closing force and bite force (p = 0.002).

• Journal of the Korean Society of Marine Environment & Safety
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• v.15 no.3
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• pp.251-256
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• 2009

In this research, we experimentally studied flow characteristic by applying PIV measuring techniques which could measure the point velocity of all flow field and measuring the unsteady velocity of surrounding disk generated in a short time. Time range of great velocity change following quick closing of the slide valve was within 0.1s and the cycle was presumed to be 0.12s as a result of comparison study between the result of point flow field and of existing pressure change. Also, surrounding disk flow inside the circular pipe was closed from the upper part and flow road was getting narrow and advanced to the lower part incidentally quickly there was a tendency that the size of the flow back velocity to the upper part immeadiately after the closure decreased to 4/120s and increased again. There was flow back velocity component in y/D=0.2 lower part by the influence of flow back to the upper part after complete closure and the vortex flow of 0.2D-size near y/D=0.7, x/D=-0.3 was observed.

• Tunnel and Underground Space
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• v.21 no.2
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• pp.128-137
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• 2011

The shut-in pressure calculated in common hydrofracturing test for vertical borehole equals generally to the minimum horizontal principal stress, so it should be considered as an essential parameter for determining the in-situ stress regime around the rock mass. It shows usually an ambiguous value in pressure-time history curves, however, because of the relationship between the behavior of hydraulic fractures and the condition of remote stress regime. In this study, a series of numerical analyses have been carried out to compare several methods for determining the shut-in pressure during hydrofracturing. The hydraulic-mechanical coupling has been applied to numerical analysis for simulating the fracture propagation by hydraulic pressure, and the different discontinuity geometry has been considered in numerical models to examine the effect of numerical element shape on fracture propagation pattern. From the numerical simulations with the four different discontinuity geometries, it was revealed that the shut-in pressure obtained from graphical methods rather than statistical method was relatively small. Consequently a care should be taken in selecting a method for determining the shut-in pressure when a stress anomaly around borehole and a fracture propagation with complicate mechanism are considered.

• Pediatric Infection and Vaccine
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• v.28 no.2
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• pp.57-65
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• 2021

School closures during the coronavirus disease 2019 (COVID-19) pandemic have been outlined in studies from different disciplines, including economics, sociology, mathematical modeling, epidemiology, and public health. In this review, we discuss the implications of school closures in the context of the current COVID-19 pandemic. Modeling studies of the effects of school closures, largely derived from the pandemic influenza model, on severe acute respiratory syndrome coronavirus 2 produced conflicting results. Earlier studies assessed the risk of school reopening by modeling transmission across schools and communities; however, it remains unclear whether the risk is due to increased transmission in adults or children. The empirical findings of the impact of school closures on COVID-19 outbreaks suggest no clear effect, likely because of heterogeneity in community infection pressure, differences in school closure strategies, or the use of multiple interventions. The benefits of school closings are unclear and not readily quantifiable; however, they must be weighed against the potential high social costs, which can also negatively affect the health of this generation.

• Journal of the Korean Society of Radiology
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• v.84 no.5
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• pp.1152-1157
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• 2023

Common carotid artery occlusion (CCAO) is a very rare disorder that has rarely been studied. CCAO causes several neurological symptoms but can sometimes be asymptomatic due to the development of various anastomoses. Herein, we report the case of a 70-year-old male patient diagnosed with asymptomatic CCAO due to anastomotic flow. The patient underwent transfemoral cerebral angiography (TFCA) and was found to have CCAO with two collateral pathways, including an occipital artery-vertebral artery anastomosis. We emphasize the importance of TFCA when CCAO is suspected and review the types and anastomotic pathways of CCAO.

• The Korean Journal of Nuclear Medicine
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• v.36 no.5
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• pp.306-313
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• 2002

Purpose: Diuretic renography (DR) can be false negative in patients with upper urinary tract obstruction due to low compliance of the renal pelvis. Delayed parenchymal transit (DPT) may be a valuable sign in case of false negative DR. We compared the diagnostic values of DR and DPT during Tc-99m MAG3 diuretic scan in adults with suspected unilateral obstructive uropathy. Materials and Methods: Fifty-four patients(male:female=30:24, age: $40.7{\pm}15.5$ yrs) who underwent Tc-99m MAG3 diuretic scan due to suspicious unilateral obstructive uropathy were analyzed. DR with a $T_{1/2}\;of\;>\;15min$ was considered as positive for obstruction. DPT was considered to be present when there was delayed appearance of radioactivity in the renal pelvis and prolonged retention of radioactivity in the renal parenchyma. The renal area ratio was defined as the ratio of pixel number of hydronephrotic kidney over that of normal contralateral at $1{\sim}2min$ images. Definition of obstruction was improved hydronephrosis after intervention, or aggravated hydronephrosis without intervention. Non-obstruction was defined as unchanged hydronephrosis over 6 months. Results: Twenty-six renal units had obstruction and 28 no obstruction. The sensitivities of DR and DPT were 69% (18/26) and 50% (13/26) respectively. Two renal units with DPT but negative DR showed the renal area ratio of <1.1. Among the 20 obstructive renal units with DPT or positive DR, 13 with DPT had lower renal area ratio than 7 renal units without DPT ($0.97{\pm}0.20\;vs\;1.30{\pm}0.41,\;p<0.05$). Differential renal function was not significantly different between these groups. DPT correctly diagnosed all renal units with non-obstruction (specificity 100%), while the specificity of DR was 89% (25/28). Conclusion: DPT during Tc-99m MAG3 diuretic scan may be a valuable sign in diagnosing urinary obstruction especially in patients with false negative DR and early HN.

• Clinical and Experimental Pediatrics
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• v.46 no.9
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• pp.871-875
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• 2003

Purpose : This study was performed to follow the natural course and size change of isolated atrial septal defect(ASD) secundum. Methods : Among the newly diagnosed with ASD secundum at the division of pediatric cardiology in Yonsei cardiovascular hospital from January 1996 to December 2000, 89 patients with pure ASD secundum were checked by the serial echocardiographic evaluation to measure the size change. Results : There was a statistical difference(P<0.05) in the rate of spontaneous closure and size change of the defect between the group of bigger defect(>8 mm) and the group of smaller defect (${\leq}8mm$). There was also a statistical difference(P<0.05) in the rate of spontaneous closure and size change of the defect between the group of younger than three years of age and the group of older than three years of age. The initial size of the defect and change of size were the significant influencing factors in the rate of spontaneous closing of ASD. In the group of patients who have persistent ASD, the size of defect showed a tendency of increasing size of defect with the age(P<0.005); however in the correction of these values by the body surface area of each patients, there was no statistical difference. Conclusion : The possibility of spontaneous closure of pure ASD secundum was higher in the group of patients who have smaller defect and who were younger. The ASD secundum that did not have spontaneous closure showed an increase in size with the growth of the patients; however when this size was corrected by the body surface area, there was no statistical difference. The closure of the defect was at 26.2 months of age so close follow-up of the patients is important.