• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.6
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• pp.469-484
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• 2021

Rock mass classification results have a great influence on construction schedule and budget as well as tunnel stability in tunnel design. A total of 3,526 tunnels have been constructed in Korea and the associated techniques in tunnel design and construction have been continuously developed, however, not many studies have been performed on how to assess rock mass quality and grade more accurately. Thus, numerous cases show big differences in the results according to inspectors' experience and judgement. Hence, this study aims to suggest a more reliable rock mass classification (RMR) model using machine learning algorithms, which is surging in availability, through the analyses based on various rock and rock mass information collected from boring investigations. For this, 11 learning parameters (depth, rock type, RQD, electrical resistivity, UCS, V_p, V_s, Young's modulus, unit weight, Poisson's ratio, RMR) from 13 local tunnel cases were selected, 337 learning data sets as well as 60 test data sets were prepared, and 6 machine learning algorithms (DT, SVM, ANN, PCA & ANN, RF, XGBoost) were tested for various hyperparameters for each algorithm. The results show that the mean absolute errors in RMR value from five algorithms except Decision Tree were less than 8 and a Support Vector Machine model is the best model. The applicability of the model, established through this study, was confirmed and this prediction model can be applied for more reliable rock mass classification when additional various data is continuously cumulated.

• Journal of the Korean Chemical Society
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• v.67 no.5
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• pp.378-392
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• 2023

The purpose of this study is to analyze the pre-service chemistry teachers' cognition of the nature of model in process of designing and developing models using technology. For this purpose, 19 pre-service chemistry teachers' in the 3rd grade of a education college located in the central region observe experimental phenomena related to Boyle's law presented in the 7th grade science textbook and researchers required the design and development of a model related to the observed experimental results using technology. Based on previous studies, the nature of model were classified into two aspect: 'Representational aspect' and 'Explanatory aspect'. The 'Representational aspect' was classified into 'Representation', 'Abstraction', and 'Simplification', and the 'Explanatory aspect' was classified into 'Analysis', 'Interpretation', 'Reasoning', 'Explanation', and 'Quantification'. The pre-service chemistry teachers' cognition were analyzed by the classification. As a result of the study, the 'Representation' of the 'expressive aspect' was uniformized in the form of space that changes in volume, and the pressure was expressed as the Brightness inside the cylinder or frequency of color change of particles for 'Abstraction'. In the case of 'Simplification', the particle collision was expressed as a perfectly elastic collision, but there was a group that could not simply indicate the type of particle. In the 'Explanatory aspect', in the case of 'Analysis', volume was classified as a manipulated variable, and in the case of 'Interpretation', most groups analyzed the change in pressure through the collision of gas particles. However, the cognition involved in 'Reasoning' was not observed much. In the case of 'Explanation', there were groups that did not succeed in explanation because the area where the particles collided was not set or incorrectly set, and in the case of 'Quantification', there was a group that formulated the number of collisions per unit time, and on the contrary, there was a group that could not quantify the number of collisions because they could not be expressed in numbers.

• Journal of Practical Agriculture & Fisheries Research
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• v.17 no.1
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• pp.57-71
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• 2015

This study was conducted to develop the fertigation system with a peristaltic hose pump and brushless DC motor. The fertigation system was consisted of sensor, main controller, motor control unit, peristaltic pump, water supply pump, control panel, and filter. The peristaltic pump discharges liquid by squeezing the tube with rollers. Rollers attached to the external circumference of the rotor compresses the flexible tube. The fluid is contained within a flexible tube fitted inside a circular pump casing. The developed fertigation system has no mixing tank but instead injects directly a concentrated nutrient solution into a water supply pipe. The revolution speed of the peristaltic pump is controlled by PWM (Pulse width modulation) method. When the revolution speed of the peristaltic pump was 300rpm, the flow rate of the 3.2, 4.8, 6.3mm diameter tube was 202, 530, 857mL/min, respectively. As increasing revolution speed, the flow rate of the peristaltic pump linearly increased. As the inner diameter of a tube larger, a slope of graph is more steep. Flow rate of three roller was more than that of four roller. Flow rate of a norprene tube with good restoring force was more than that of a pharmed tube. As EC sensor probe was installed in direct piping in comparison with bypass piping showed good performance. After starting the system, it took 16~17 seconds to stabilize EC. The maximum value of EC was 1.44~1.7dS/m at a setting value of 1.4dS/m. The developed fertigation system showed ±0.06dS/m deviation from the setting value of EC. In field test, Cucumber plants generally showed good growth. From these findings, this fertigation system can be appropriately suitable for fertigation culture for crops.

• Korean Journal of Construction Engineering and Management
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• v.24 no.6
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• pp.24-35
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• 2023

Recently, the Ministry of Land, Infrastructure and Transport presented the '6th Construction Technology Promotion Basic Plan' and 'Smart Construction Revitalization Plan (2022.7.20)'. Off-Site Construction (OSC), which involves construction and production of PC (Precast Concrete) and Modular, etc., has advantages in shortening the construction period, reducing costs, improving quality, reducing construction waste, and reducing safety accidents. However, the construction cost is high compared to the traditional RC construction method, which has hindered its utilization and spread. In this study, OSC utilization was improved. An economic analysis indicator and methodology that can support decision-making in the planning and design stages for multi-unit housing were proposed. The factors used in the economic analysis of OSC (based on the PC method) of apartment houses were reviewed. As for the indicators used in the cost and benefit section, 'Construction Period', 'Disaster Occurrence', 'Waste Generation', and 'Greenhouse gas Emission', which reflect the technical advantages of OSC, were derived. In addition, a scenario analysis was conducted based on actual apartment housing case data for the presented economic analysis indicators and benefit calculation standards. The level of benefit that offsets the difference between the existing RC construction method and the construction cost was reviewed. In future studies, it will be necessary to conduct additional case studies to apply the measurement criteria for detailed indicators and supplement the benefit indicators.

• Journal of the Korean Society of Radiology
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• v.82 no.4
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• pp.923-935
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• 2021

Purpose We aimed to assess the clinical efficacy of transcatheter arterial embolization (TAE) for treating hemothorax caused by chest trauma. Materials and Methods Between 2015 and 2019, 68 patients (56 male; mean age, 58.2 years) were transferred to our interventional unit for selective TAE to treat thoracic bleeding. We retrospectively investigated their demographics, angiographic findings, embolization techniques, technical and clinical success rates, and complications. Results Bleeding occurred mostly from the intercostal arteries (50%) and the internal mammary arteries (29.5%). Except one patient, TAE achieved technical success, defined as the immediate cessation of bleeding, in all the other patients. Four patients successfully underwent repeated TAE for delayed bleeding or increasing hematoma after the initial TAE. The clinical success rate, defined as no need for thoracotomy for hemostasis after TAE, was 92.6%. Five patients underwent post-embolization thoracotomy for hemostasis. No patient developed major TAE-related complications, such as cerebral infarction or quadriplegia. Conclusion TAE is a safe, effective and minimally invasive method for controlling thoracic wall and intrathoracic systemic arterial hemorrhage after thoracic trauma. TAE may be considered for patients with hemothorax without other concomitant injuries which require emergency surgery, or those who undergoing emergency TAE for abdominal or pelvic hemostasis.

• 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.

• Pediatric Infection and Vaccine
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• v.30 no.3
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• pp.111-120
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• 2023

Purpose: Human rhinovirus (HRV) infections can result in lower respiratory tract infections (LRTIs). We aimed to investigate the characteristics of severe HRV LRTI in young children. Methods: Medical records were reviewed retrospectively in patients who were hospitalized for HRV LRTIs from 2016 to 2020 at the Samsung Medical Center in Seoul, Korea. Patients aged 90 days or older and younger than 5 years were included. Patients with co-infections with other respiratory pathogens were excluded. Severe HRV LRTI was defined as the following: the need for high-flow oxygenation, mechanical ventilation, or intensive care unit admission. Results: A total of 115 cases were identified. The median age was 17 months (range, 3-56 months) and the median hospital days were 4 days (range, 2-31 days). Of the 115 cases, 18 patients (15.7%) developed severe HRV LRTI. The median age was younger in the severe group compared to the non-severe group (9.5 months vs. 19.0 months, P=0.001). Of 18 patients with severe HRV LRTI, 11 (61.1%) had underlying diseases - chronic lung diseases accounted for the largest proportion (63.6%). Six patients (33.3%) required mechanical ventilation. Of note, 7 previously healthy children were diagnosed with severe HRV LRTI. Of those 7 children, 4 of them were diagnosed with asthma later. When the 115 cases were divided into previously healthy (n=60) and underlying disease (n=55) groups, severe courses of HRV LRTI were observed in 11.7% and 20.0% of children, respectively (P=0.219). Conclusions: HRV can cause severe LRTI even in previously healthy children as well as in children with comorbidities.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.68 no.4
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• pp.438-444
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• 2023

Italian ryegrass (Lolium multiflorum Lam.; IRG) sowing season is delayed due to the autumn rainy season. Therefore, to address this problem, transplanting date and plant density were investigated. Transplant times investigated were October 20th, October 30th, and November 10th and planting densities were 50, 70, and 80 hills per 3.3 m². The plant height, leaf area index, and plant coverage rate were high in the following order: October 20th, October 30th, and November 10th. There was no significant difference among planting densities. In addition, the number of tillers and dry weight before and after wintering were high on October 20th. In terms of yield components, the number of tillers, dry weight, and seed yield per unit area were higher with the transplanting date of October 20th than with transplanting on November 10th. There was no difference in seed yield between the planting densities of 80 and 70 hills per 3.3 m². However, seed yield was low at 50 hills per 3.3 m². In conclusion, the transplanting time for stable seed production is late October, and optimal plant density is 70 and 80 hills per 3.3 m². A stable interplanting number before wintering will contribute to the seed yield.

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.4
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• pp.540-548
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• 2015

This study examined the cultural characteristics and biological activities of fermented rice and amaranth with Bacillus subtilis KMKW4. These samples were made with various amounts of rice and amaranth [100:0 (R100), 90:10 (R90), 80:20 (R80), and 70:30 (R70)]. B. subtilis KMKW4 was used as starter for the fermentation, and its cultures at the lated logarithmic growth were inoculated for final concentration of 2% (v/v). Number of viable cells of fermented R80 (7.67 log CFU/mL) was greater than those of R100, R90, and R70 (7.48 log CFU/mL, 7.38 log CFU/mL, and 7.09 CFU/mL, respectively) during the fermentation period (120 h). Amylase activities of fermented R80 and R100 were 57.77 U/mL and 19.91 U/mL, respectively. Furthermore, amylase activities of fermented freeze-dried powders of R100 and R80 were 24.31 U/g and 9.12 U/g, respectively. Free sugar contents of R100 and R80 increased after fermentation, and that of R80 (5,454.15 mg/100 g) significantly increased compared to that of R100 (4,274.85 mg/100 g). The free amino acid content of R80 was higher than that of R100. DPPH and superoxide radical scavenging activities of 5 mg/mL of fermented freeze-dried powder (R80) were 44.21% and 89.76%, respectively. ACE inhibition rates and ${\alpha}$-glucosidase inhibitory activities were significantly higher in R80 than R100. This study suggested that fermentation of R80 might be a new potential source of antioxidant, anti-diabetic, and anti-hypertensive agents applicable to grain enzyme-containing foods.

• Clinical and Experimental Pediatrics
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• v.52 no.4
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• pp.481-487
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• 2009

Purpose : This study investigated the clinical course and prognostic factor of very low birth weight infants (VLBWI) with hemodynamically significant congenital heart defects (CHDs). Methods : Medical records of 1,098 VLBWI with birth weight <1,500 g who had been admitted to the neonatal intensive care unit of Samsung Medical Center from October 1994 to December 2007 were reviewed retrospectively. The data for these patients with hemodynamically significant CHD (n=33) were compared with those without CHD (n=1,065). Results : The incidence of CHD was 3.0% (33 patients) 7 patients (21%) had CHD combined with the congenital abnormalities or chromosomal disorders. The most common CHD was a ventricular septal defect. The incidence of intrauterine growth retardation was higher in patients with CHD than in patients without CHD (34% vs. 20%), but there were no significant differences in gestational age, birth weight, respiratory distress syndrome, bronchopulmonary dysplasia, necrotizing enterocolitis, severe intraventricular hemorrhage (${\geq}$Gr III), and periventricular leukomalacia. Cardiac surgery was performed on 13 patients (39%). Nine patients received staged operations, and 10 patients received early intervention. The overall mortality in patients who had CHD was higher than in the patients who did not have CHD (27% vs. 16%). In patients with CHD, congenital abnormalities or chromosomal disorders were more important factors for increased mortality (86% vs. 11%) than the degree of complexity of CHD (19% vs. 42%). Conclusion : The most important prognostic factors of VLBWI with CHD are the associated congenital abnormalities or chromosomal disorders.