• Pediatric Infection and Vaccine
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• v.31 no.1
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• pp.102-112
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• 2024

Purpose: To identify the epidemiological characteristics and risk factors of coronavirus disease 19 (COVID-19) outbreaks depending on the type of educational facility by analyzing the COVID-19 cluster associated with educational facilities. Methods: This study is based on epidemiological investigation of COVID-19 cluster in Gangwon-do, Korea from December 10, 2020 to September 23, 2021 reported to the Korea Disease Control and Prevention Agency's Integrated Disease and Health Management System. Four hundred seven patients in 19 facilities, classified as cluster related to educational facilities, were the study population. The result of preliminary epidemiology survey report, in-depth epidemiological survey by phone and the result of risk assessment derived from the field epidemiology investigation were retrospectively analyzed to evaluate infectivity and the characteristics of the risk factors. Results: There were total of 407 confirmed patients related to 19 educational facilities, with 204 students under the age of 19 (50.1%). One hundred fifty-five preceding spreaders were from families (38.1%) and 125 were the teachers (30.7%). The place exposed to confirmed patients was the highest with 139 people (34.2%) at home. Conclusions: It was confirmed that the cause of the occurrence of clusters related to educational facilities was higher due to family transmission than the risk of facilities in schools. Nevertheless, continuous efforts should be made to control infection in educational facilities, and that teachers' implementation of principles for prevention of COVID-19 personal hygiene in their daily lives should be strengthened.

• Journal of the Korean Institute of Landscape Architecture
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• v.52 no.2
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• pp.64-78
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• 2024

Storytelling is a communication technique to express and convey the story using various media, where the audience accepts the story, reinterprets the topic and interacts with the storyteller. It was assumed that the user's significance and awareness about the storytelling technique applied to historical theme parks would have an impact on the satisfaction of using the theme park and intention to revisit. In this study, it was purposed to derive the structural factors of spatial storytelling in historical theme parks, and to understand the impact of user's awareness and constituent factors on user responses. Based on previous researches, the structural factors of spatial storytelling in historical theme parks were derived related to theme, experientiality, unusualness, educationalness, unity, expressiveness, interactivity, and interest, and for which the users' awareness was surveyed. The survey was conducted targeting the users of Samguk Yusa Theme Park located in Gunwi-gun, Gyeongsangbuk-do, where the collected data was analyzed using EXCEL2020 and SPSS 21.0 statistical programs, and the results are as follows: First, the spatial storytelling technique applied as a conveying method of the theme of Samguk Yusa Theme Park affects users' satisfaction and intention to revisit, and most respondents responded that the storytelling was significant. Second, it showed that the significance of unusualness and educationalness among the awareness of significance of the spatial storytelling constituent factors of Samguk Yusa Theme Park has a significant impact on user's satisfaction, and the significance of unusualness, interactivity, educationalness, and interest has a significant impact on intention to revisit. Third, it showed that the awareness of interest, theme, and unity has a significant impact on user's satisfaction depending on the user's awareness of spatial storytelling constituent factors of Samguk Yusa Theme Park, and the awareness of interactivity and experientiality has a significant impact on intention to revisit. This study is meaningful in quantitative analysis and interpretation of the influence of storytelling on user's response to historical theme parks by the exploratory analysis of characteristic factors and spatial storytelling constituent factors on historical theme parks and deriving the structural factors of spatial storytelling in historical theme parks.

• Korean Journal of Environment and Ecology
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• v.38 no.2
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• pp.148-155
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• 2024

This study investigated the ecological characteristics of Odontobutis platycephala at Jaho stream from January to December 2022. The riverbed structure of the species' habitat was rich in cobble and pebble. The water was deep, ranging from 22 to 153 cm, with an average of 64 cm, and the stream velocity was rapid at 0.89 (0.42-1.46) m/sec. The ratio of females to males was 1:1.02, and the total length of collected individuals ranged from 38 to 156 mm. The age according to the total length frequency distribution as of May indicated that the group with a total length of 38-69 mm was one year old, the group with 60-99 mm was two years old, the group with 100-139 mm was three years old, and the group 140-156 mm was four years or older. As a secondary gender characteristic, the genital papilla was cylindrical in females and cone-shaped with a pointed tip in males. Some females with a length ranging from 60 to 69 mm and all females 70 mm or longer were sexually mature. Some males with a length ranging from 70 to 79 mm and all males 80 mm or longer were sexually mature. The spawning season was from May to July, and the water temperature was between 17 ℃ and 28 ℃ during that period. The prosperous spawning season was June (24 ℃). The average number of eggs in the ovaries was 988 (284-2,722) per mature female, and the mature eggs were yellowish and spherical with a mean diameter of 1.46 (1.19-1.71) mm. The correlation between total length and body weight is BW=0.00000006TL^3.12 with the constant a as 0.00000006 and the parameter b as 3.12. The mean condition factor (K) was 1.44 (0.96-2.26), and the slope was negative at -0.0007

• Journal of the Korean Society of Radiology
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• v.81 no.1
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• pp.147-156
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• 2020

Purpose The objective of this study was to evaluate the diagnostic value and threshold levels of cytokeratin fragment 21-1 (CYFRA 21-1) in fine-needle aspiration (FNA) washouts for detection of lymph node (LN) recurrence in postoperative breast cancer patients. Materials and Methods FNA cytological assessments and CYFRA 21-1 measurement in FNA washouts were performed for 64 axillary LNs suspicious for recurrence in 64 post-operative breast cancer patients. Final diagnosis was made on the basis of FNA cytology and follow-up data over at least 2 years. The concentration of CYFRA 21-1 was compared between recurrent LNs and benign LNs. Diagnostic performance and cut-off value were evaluated using a receiver operating characteristic curve. Results Regardless of the non-diagnostic results, the median concentration of CYFRA 21-1 in recurrent LNs was significantly higher than that in benign LNs (p < 0.001). The optimal diagnostic cut-off value was 1.6 ng/mL. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of CYFRA 21-1 for LN recurrence were 90.9%, 100%, 100%, 98.1%, and 98.4%, respectively. Conclusion Measurement of CYFRA 21-1 concentration from ultrasound-guided FNA biopsy aspirates showed excellent diagnostic performance with a cut-off value of 1.6 ng/mL. These results indicate that measurement of CYFRA 21-1 concentration in FNA washouts is useful for the diagnosis of axillary LN recurrence in post-operative breast cancer patients.

• Journal of the Korean Society of Radiology
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• v.81 no.2
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• pp.365-378
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• 2020

Purpose This study was performed to determine whether the T1 relaxation time of gadoxetic acid-enhanced liver MR imaging is useful for detecting and staging liver fibrosis in patients with chronic liver disease. Materials and Methods One hundred and three patients with suspected focal liver lesion underwent MR imaging and Fibroscan. Fibroscan was chosen as the reference standard for classifying liver fibrosis. T1 relaxation times were acquired before (preT1), 20 minutes after (postT1) contrast administration, and reduction rate of T1 relaxation time (rrT1) on transverse 3D VIBE (volumetric interpolated breath-hold examination) sequence using 3T MR imaging. The optimal cut-off values for the fibrosis staging were determined with ROC analysis. Results PreT1 and postT1 increased and rrT1 decreased constantly with increasing severity of liver fibrosis according to the METAVIR score (F0-F4). There were statistically significant differences between F2 and F3 in preT1 (F2, 836.0 ± 74.7 ms; F3, 888.6 ± 77.5 ms, p < 0.05) and between F3 and F4 in postT1 (F3, 309.0 ± 80.2 ms; F4, 406.6 ± 147.7 ms, p < 0.05) and rrT1 (F3, 65.4 ± 7.7%; F4, 57.3 ± 11.4%, p < 0.05). ROC analysis revealed that combination test (preT1 + postT1) was the best test for predicting liver fibrosis. Conclusion PreT1 and postT1 increased constantly with increasing severity of liver fibrosis. T1 mapping in gadoxetic acid-enhanced liver MR imaging could be a helpful complementary sequence to determine the liver fibrosis stage.

• Journal of the Korean Society of Radiology
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• v.81 no.6
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• pp.1412-1423
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• 2020

Purpose Some patients with neonatal seizures show diffuse, symmetric diffusion-restricted lesions in the cerebral white matter. The aim of this study was to describe clinical and imaging findings of patients with neonatal seizures who had diffuse, symmetric diffusion-restricted lesions without any structural or metabolic etiology. Materials and Methods A total of 56 neonates aged less than 1 week underwent brain magnetic resonance imaging (MRI) for evaluation of seizures from November 2008 to February 2017. After excluding 43 patients, 13 patients showed diffuse white matter abnormality on diffusion-weighted imaging. Initial and follow-up clinical and MRI findings were analyzed retrospectively. Results All 13 patients were born at full term. Among the ten patients who underwent a stool test for viruses, six were positive for rotavirus and one for astrovirus. MRI revealed diffuse, symmetric diffusion-restricted lesions distributed along the cerebral white matter, thalami, and midbrain variably. Conclusion Diffuse, symmetric diffusion-restricted lesions involving the cerebral white matter can be seen in patients with neonatal seizures without any structural or metabolic etiology. Rotavirus is commonly but not exclusively detected in these patients. Nevertheless, viral infection-associated encephalopathy should be considered for patients with characteristic clinical and MRI findings.

• Journal of the Korean Society of Radiology
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• v.18 no.3
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• pp.187-201
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• 2024

Osteoporosis is a major health issue globally, often remaining undetected until a fracture occurs. To facilitate early detection, deep learning (DL) models were developed to classify osteoporosis using abdominal computed tomography (CT) scans. This study was conducted using retrospectively collected data from 3,012 contrast-enhanced abdominal CT scans. The DL models developed in this study were constructed for using image data, demographic/clinical information, and multi-modality data, respectively. Patients were categorized into the normal, osteopenia, and osteoporosis groups based on their T-scores, obtained from dual-energy X-ray absorptiometry, into normal, osteopenia, and osteoporosis groups. The models showed high accuracy and effectiveness, with the combined data model performing the best, achieving an area under the receiver operating characteristic curve of 0.94 and an accuracy of 0.80. The image-based model also performed well, while the demographic data model had lower accuracy and effectiveness. In addition, the DL model was interpreted by gradient-weighted class activation mapping (Grad-CAM) to highlight clinically relevant features in the images, revealing the femoral neck as a common site for fractures. The study shows that DL can accurately identify osteoporosis stages from clinical data, indicating the potential of abdominal CT scans in early osteoporosis detection and reducing fracture risks with prompt treatment.

• Journal of the Korea Organic Resources Recycling Association
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• v.31 no.4
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• pp.51-58
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• 2023

In this study, anaerobic co-digestion was carried out using desulfurization sludge and sewage sludge (primary sludge) to evaluate the effects of sulfur compounds in anaerobic digestion. The experiment was carried out in the form of a batch test using 500 mL duran bottle, and the mixing ratio of the feedstock was selected based on the ratio of COD/SO₄. As a result of the experiment, it was confirmed that the amount of biogas generated and the yield decreased at the mixing ratio of COD/SO₄ 20 or less. In particular, below COD/SO₄ 10, it was lower than seed (283.5 mL) which was set without feedstock to correct biogas generated by itself from seed sludge. Methane yield tended to decrease from a ratio of COD/SO₄ 20 or less to 0.135 m³/kg VS compared to 0.396 m³/kg VS of COD/SO₄ 50. In addition, compared to 0.0097 m³/kg VS of hydrogen sulfide yield from COD/SO₄ 50, the ratio of COD/SO₄ 20 increased sharply to 0.0223 m³/kg VS, and in particular, the highest result was 0.0855 m³/kg VS in COD/SO₄ 10. Based on these results, it is judged that the effect of sulfide in anaerobic digestion can have an adverse effect if the COD/SO₄ ratio decreases to less than 20.

• Journal of the Korean Society of Radiology
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• v.84 no.5
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• pp.1094-1109
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• 2023

Purpose To investigate whether CT-based tumor regression grade (ctTRG) can be used to predict the response to neoadjuvant chemotherapy (NAC) in colon cancer. Materials and Methods A total of 53 patients were enrolled. Two radiologists independently assessed the ctTRG using the length, thickness, layer pattern, and luminal and extraluminal appearance of the tumor. Changes in tumor volume were also analyzed using the 3D Slicer software. We evaluated the association between pathologic TRG (pTRG) and ctTRG. Patients with Rödel's TRG of 2, 3, or 4 were classified as responders. In terms of predicting responder and pathologic complete remission (pCR), receiver operating characteristic was compared between ctTRG and tumor volume change. Results There was a moderate correlation between ctTRG and pTRG (ρ = -0.540, p < 0.001), and the interobserver agreement was substantial (weighted κ = 0.672). In the prediction of responder, there was no significant difference between ctTRG and volumetry (Az = 0.749, criterion: ctTRG ≤ 3 for ctTRG, Az = 0.794, criterion: ≤ -27.1% for volume, p = 0.53). Moreover, there was no significant difference between the two methods in predicting pCR (p = 0.447). Conclusion ctTRG might predict the response to NAC in colon cancer. The diagnostic performance of ctTRG was comparable to that of CT volumetry.

• Journal of the Korean Society of Radiology
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• v.84 no.1
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• pp.185-196
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• 2023

Purpose This study aimed to investigate radiomics analysis of ultrasonographic images to develop a potential biomarker for predicting lymph node metastasis in papillary thyroid carcinoma (PTC) patients. Materials and Methods This study included 431 PTC patients from August 2013 to May 2014 and classified them into the training and validation sets. A total of 730 radiomics features, including texture matrices of gray-level co-occurrence matrix and gray-level run-length matrix and single-level discrete two-dimensional wavelet transform and other functions, were obtained. The least absolute shrinkage and selection operator method was used for selecting the most predictive features in the training data set. Results Lymph node metastasis was associated with the radiomics score (p < 0.001). It was also associated with other clinical variables such as young age (p = 0.007) and large tumor size (p = 0.007). The area under the receiver operating characteristic curve was 0.687 (95% confidence interval: 0.616-0.759) for the training set and 0.650 (95% confidence interval: 0.575-0.726) for the validation set. Conclusion This study showed the potential of ultrasonography-based radiomics to predict cervical lymph node metastasis in patients with PTC; thus, ultrasonography-based radiomics can act as a biomarker for PTC.