• Journal of Welding and Joining
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• v.31 no.6
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• pp.50-57
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• 2013

Characterization of microstructures and cryogenic mechanical properties of electro beam (EB) welds between cast and forged Inconel 718 superalloys has been investigated. Optimal EBW condition was found in the beam current range of 36~39 mA with the constant travel speed of 12 mm/s and arc voltage of 120 kV for 10 mm-thick specimens. Electron beam current lower than 25 mA caused to occur the liquation microfissuring in cast-side heat affected zone (HAZ) of EB welds. The HAZ liquation microfissure was found on the liquated grain boundaries with resolidified ${\gamma}/Laves$ and ${\gamma}/NbC$ eutectic constituents. EBW produced welds showing a fine dendritic structure with relatively discrete Laves phase due to fast cooling rate. After post weld aging treatment, blocky Laves phase and formation of ${\gamma}^{\prime}+{\gamma}^{{\prime}{\prime}}$ strengtheners were observed. Presence of primary strengthener and coarse Laves particles in PWHT weld may cause to reduce micro-plastic zone ahead of a crack, leading to a significant decrease in Charpy impact toughness at $-196^{\circ}C$. Fracture initiation and propagation induced by Charpy impact testing were discussed in terms of the dislocation structures ahead of crack arisen from the fractured Laves phase.

• Journal of The Korean Society of Grassland and Forage Science
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• v.4 no.2
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• pp.133-139
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• 1983

To compare animal production and grazing behavior, Wye college rotational, set stocking, modified set stocking and zero grazing system were set in Alpine area. Each system has one hectar and 4 head of Korean native cow. In order to investigate grazing behavior, eye observation was made every 2.5 minute for 15 hours of daylight from 5 a.m. to 20p.m. Results obtained were as follows. 1. The system of Wye college and rotational grazing have greater output of live weight per hectar than that of other gazing system applied. But practically rotational and modified set stocking were thought to be convenient grazing system for hill pasture and also modified set stocking was simple to operate, so that it seemed to be recommended as an alternative to rotational grazing system. 2. The daily live weight gain was the highest in May, the lowest in July and after then steadily increased. 3. Grazing hour during daylight varied from 331.1 min to 576.0 min by grazing system, but by season, herbage availability, weather condition. 4. Korea native cow tended to have three primary grazing time begining at one hour after sunrise, noon, and around 15p.m.

• Journal of Dental Rehabilitation and Applied Science
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• v.34 no.4
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• pp.317-323
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• 2018

When oral cancer develops in the maxilla, oro-nasal communication occurs after surgical treatment including removal of the primary site. Restoration through an obturator is necessary to prevent food from storing due to non-oral opening, and to ensure proper pronunciation and aesthetic restoration. In this case, the patient was treated with right hemi-maxillectomy due to oral cancer and has residual abutment and poor periodontal support due to the effect of head and neck radiotherapy. The obturator was treated with a hybrid telescopic double crown denture. Reporting a successful prognosis in 18 months of follow-up.

• Nuclear Engineering and Technology
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• v.51 no.7
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• pp.1738-1748
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• 2019

Previous research has shown that the inclined condition has an impact on the natural circulation (natural circulation) mode operation of Floating Nuclear Power Plant (FNPP) mounted on the movable marine platform. Due to its compact structure, small volume, strong maneuverability, the Integral Pressurized Water Reactor (IPWR) is adopted as marine reactor in general. The OTSGs of IPWR are symmetrically arranged in the annular region between the reactor vessel and core support barrel in this paper. Therefore, many parallel natural circulation loops are built between the core and the OTSGs primary side when the main pump is stopped. and the inclined condition would lead to discrepancies of the natural circulation drive head among the OTSGs in different locations. In addition, the flow rate and temperature nonuniform distribution of the core caused by inclined condition are coupled with the thermal hydraulics parameters maldistribution caused by OTSG group operating mode on low power operation. By means of the RELAP5 codes were modified by adding module calculating the effect of inclined, heaving and rolling condition, the simulation model of IPWR in inclined condition was built. Using the models developed, the influences on natural circulation operation by inclined angle and OTSG position, the transitions between forced circulation (forced circulation) and natural circulation and the effect on natural circulation operation by different OTSG grouping situations in inclined condition were analyzed. It was observed that a larger inclined angle results the temperature of the core outlet is too high and the OTSG superheat steam is insufficient in natural circulation mode operation. In general, the inclined angle is smaller unless the hull is destroyed seriously or the platform overturn in the ocean. In consequence, the results indicated that the IPWR in the movable marine platform in natural circulation mode operation is safety. Selecting an appropriate average temperature setting value or operating the uplifted OTSG group individually is able to reduce the influence on natural circulation flow of IPWR by inclined condition.

• Clinical and Experimental Otorhinolaryngology
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• v.11 no.4
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• pp.301-308
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• 2018

Objectives. The age-based Cole formula has been employed for the estimation of endotracheal tube (ETT) size due to its ease of use, but may not appropriately consider growth rates among children. Child growth is assessed by calculating the body surface area (BSA). The association between the outer diameter of an appropriate uncuffed-endotracheal-tube (ETT-OD) and the BSA values of patients at 24-96 months of age was our primary outcome. Methods. Cole formula, BSA, age, height, weight and ultrasound measurement of subglottic-transverse-diameter were evaluated for correlations with correct uncuffed ETT-OD. The Cole formula, BSA, and ultrasound measurements were analyzed for estimation rates in all patients and age subgroups. The maximum allowed error for the estimation of ETT-OD was ${\leq}0.3mm$. Patients' tracheas were intubated with tubes chosen by Cole formula and correct ETT-OD values were determined using leak test. ETT exchange rates were recorded. Results. One-hundred twenty-seven patients were analyzed for the determination of estimation rates. Thirteen patients aged ${\geq}72months$ were intubated with cuffed ETT-OD of 8.4 mm and were accepted to need uncuffed ETT-OD >8.4 mm in order to be included in estimation rates, but excluded from correlations for size analysis. One-hundred fourteen patients were analyzed for correlations between correct ETT-OD (determined by the leak test) and outcome parameters. Cole formula, ultrasonography, and BSA had similar correct estimation rates. All three parameters had higher underestimation rates as age increased. Conclusion. The Cole formula, BSA, and ultrasonography had similar estimation rates in patients aged ${\geq}24$ to ${\leq}96months$. BSA had a correct estimation rate of 40.2% and may not be reliable in clinical practice to predict uncuffed-ETT-size.

• Korean Journal of Metals and Materials
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• v.48 no.1
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• pp.28-38
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• 2010

High temperature high cycle and low cycle fatigue deformation behavior of automotive heat resistant aluminum alloys (A356 and A319 based) were investigated in this study. The microstructures of both alloys were composed of primary Al-Si dendrite and eutectic Si phase. However, the size and distribution for eutectic Si phase varied: a coarse and inhomogeneous distributed was observed in alloy B (A319 based). A brittle intermethallic phase of ${\alpha}-Fe\;Al_{12}(Fe,Mn)_3Si_2$ was detected only in B alloy. Alloy B exhibited high fatigue life only under a high stress amplitued condition in the high cycle fatigue results, whereas alloy A showed high fatigue life when stress was lowered. With regard to the low-cycle fatigue result ($250^{\circ}C$) showing higher fatigue life as ductility increased, alloy A demonstrated higher fatigue life under all of the strain amplitude conditions. Fractographic observations showed that large porosities and pores near the outside surface could be the main factor in the formation of fatigue cracks. In alloy B. micro-cracks were formed in both the brittle intermetallic and coarse Si phasese. These micro-cracks then coalesced together and provided a path for fatigue crack propagation. From the observation of the differences in microstructure and fractography of these two automotive alloys, the authors attempt to explain the high-temperature fatigue deformation behavior of heat resistant aluminum alloys.

• Journal of the Korean Orthopaedic Association
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• v.55 no.5
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• pp.359-365
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• 2020

Developmental dysplasia of the hip broadly includes inadequate development of the hip joint involving the acetabulum or proximal femur, or both. Although ultrasonographic studies in neonates have greatly lowered the frequency of neglected or operatively treated cases, its sensitivity is less than desired. Hip dysplasia without subluxation is commonly diagnosed incidentally and strongly related to degenerative arthritis in females after the 4th decade. Hip dysplasia with subluxation shows symptoms through various periods, depending on its severity, especially for women with onset during pregnancy. A complete physical examination and early treatment for neonates are extremely important for obtaining satisfactory outcomes. To avoid underdiagnosis and to serve appropriate treatment on time, the authors recommend examining any suspicious hips in infants under two years of age. The study will discuss the diagnosis and primary treatment of developmental dysplasia of the hip.

• Journal of Trauma and Injury
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• v.35 no.1
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• pp.3-11
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• 2022

Purpose: The increasing use of electric personal mobility devices (ePMDs) has been accompanied by an increasing incidence of associated accidents. This study aimed to investigate the characteristics of ePMD-related injuries and their associated factors. Methods: This cross-sectional study was conducted using data from the Emergency Department-based Injury In-depth Surveillance database from 2014 to 2018. All patients who were injured while operating an ePMD were eligible. The primary outcome was the rate of severe injury, defined as an excess mortality ratio-adjusted Injury Severity Score of ≥25. We calculated the adjusted odds ratios (AORs) of outcomes associated with ePMD-related injuries. Results: Of 1,391,980 injured patients, 684 (0.05%) were eligible for inclusion in this study. Their median age was 28 years old, and most injuries were sustained by men (68.0%). The rate of ePMD-related injuries increased from 3.1 injuries per 100,000 population in 2014 to 100.3 per 100,000 population in 2018. A majority of the injuries occurred on the street (32.7%). The most commonly injured area was the head and face (49.6%), and the most common diagnosis was superficial injuries or contusions (32.9%). Being aged 55 years or older (AOR, 3.88; 95% confidence interval, 1.33-11.36) and operating an ePMD while intoxicated (AOR, 2.78; 95% confidence interval, 1.52-5.08) were associated with severe injuries. Conclusions: The number of emergency room visits due to ePMD-related injuries is increasing. Old age and drunk driving are both associated with serious injuries. Active traffic enforcement and safety regulations regarding ePMDs should be implemented to prevent severe injuries caused by ePMD-related accidents.

• Clinical and Experimental Reproductive Medicine
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• v.49 no.4
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• pp.259-269
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• 2022

Objective: Animal-free scaffolds have emerged as a potential foundation for consistent, chemically defined, and low-cost materials. Because of its good potential for high biocompatibility with reproductive tissues and well-characterized scaffold design, we investigated whether polyglycolic acid (PGA) could be used as an animal-free scaffold instead of natural fibrin-agarose, which has been used successfully for three-dimensional human endometrial cell culture. Methods: Isolated primary endometrial cells was cultured on fibrin-agarose and PGA polymers and evaluated various design parameters, such as scaffold porosity and mean fiber diameter. Cytotoxicity, scanning electron microscopy (SEM), and immunostaining experiments were conducted to examine cell activity on fabricated scaffolds. Results: The MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay and SEM results showed that endometrial cells grew and proliferated on both scaffolds. Immunostaining showed cytokeratin and vimentin expression in seeded cells after 7 days of culture. On both scaffolds, an epithelial arrangement of cultured cells was found on the top layer and stromal arrangement matrix on the bottom layer of the scaffolds. Therefore, fibrin-agarose and PGA scaffolds successfully mimicked the human endometrium in a way suitable for in vitro analysis. Conclusion: Both fibrin-agarose and PGA scaffolds could be used to simulate endometrial structures. However, because of environmental and ethical concerns and the low cost of synthetic polymers, we recommend using PGA as a synthetic polymer for scaffolding in research instead of natural biomaterials.

• Journal of Trauma and Injury
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• v.36 no.1
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• pp.39-48
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• 2023

Purpose: Sports offer several health benefits but are not free of injury risk. Activity dynamics vary across sports, impacting the injury profile and thereby influencing healthcare resource utilization and health outcomes. The purpose of this study was to investigate sports-related major trauma cases and compare differences across sports and activity groups. Methods: A retrospective case notes review of sports-related major traumas over a 5-year period was conducted. Demographic, hospital episode-related, and health outcome-related data were analyzed, and differences were compared across sports and activity groups. The Glasgow Outcome Scale (GOS) at discharge was used as the primary outcome measure and the length of hospital stay as the secondary outcome measure. Results: In total, 76% of cases had good recovery at discharge (GOS, 5), 19% had moderate disability (GOS, 4), and 5% had severe disability (GOS, 3). The mean length of hospital stay was 11.2 days (range, 1-121 days). The most severely injured body region was the limbs (29.1%) and vertebral/spinal injuries were most common (33%) in terms of location. A significant difference (P<0.05) existed in GOS across sports groups, with motor sports having the lowest GOS. However, no significant differences (P>0.05) were found in other health-outcome variables or injury patterns across sports or activity groups, although more competitive sports cases (67%) required admission than recreational sports cases (33%). Conclusions: Spinal injuries are the most frequent sports injuries, bear the worst health outcomes, and warrant better preventive measures. Head injuries previously dominated the worst outcomes; this change is likely due to better preventive and management modalities. Competitive sports had a higher injury frequency than recreational sports, but no difference in health outcomes or injury patterns.