• Steel and Composite Structures
• /
• v.22 no.6
• /
• pp.1417-1443
• /
• 2016

Cellular and castellated steel beams are used to obtain higher stiffness and bending capacity using the same weight of steel. In addition, the beam openings may be used as a pass for different mechanical fixtures such as ducts and pipes. The aim of this study is to investigate the effect of different parameters on both elastic and inelastic critical buckling stresses of steel web plates with openings. These parameters are plate aspect ratio; opening shape (circular or rectangular); end distance to the first opening; opening spacing; opening size; plate slenderness ratio; steel grade; and initial web imperfection. The web/flange interaction has been simplified by web edge restraints representing simply supported boundary conditions. A numerical parametric study has been performed through linear and nonlinear finite element (FE) models, where the FE results have been verified against both experimental and numerical results in the literature. The web plates are subject to in-plane linearly varying compression with different loading patterns, ranging from uniform compression to pure bending. A buckling stress modification factor (${\beta}$-factor) has been introduced as a ratio of buckling stress of web plate with openings to buckling stress of the corresponding solid web plate. The variation of ${\beta}$-factor against the aforementioned parameters has been reported. Furthermore, the critical plate slenderness ratio separating elastic buckling and yielding has been identified and discussed for two steel grades of DIN-17100, namely: ST-37/2 and ST-52/3. The FE results revealed that the minimum ${\beta}$-factor is 0.9 for web plates under uniform compression and 0.7 for those under both compression and tension.

• The Korean Journal of Food & Health Convergence
• /
• v.6 no.3
• /
• pp.23-29
• /
• 2020

Blood transfusion in the neonatal period remains a therapeutic act, that no one dares to consider it as perfectly innocuous and that it is advisable to make rare, considering its risks as well immunological as infectious. The present work is a retrospective study, conducted in neonatal intensive care unit, in the University Hospital MOHAMED VI, Marrakech, during the period from January 1^st to December 31^st, 2019. All newborns were included in this work, who received one or multiple transfusions of red blood cells (RBC). Our study covered 60 neonates with a total of birth: 794 neonates, with a prevalence of 7.55%, hospitalized for various indications (60% of newborns were at term, 31.7% premature and 8, 33% were post-mature. The majority of transfusion procedures were performed during the first week of life. This is explained by the frequency of haemolytic anemias by fœto-maternal incompatibility. The main indications for transfusion were haemolysis, anemic syndrome and haemorrhagic syndrome. The average number of transfusion episodes was 1.95 +/- 1.47 per patient. Newborns were polytransfused in 18.33% of cases. A single transfusion accident was found in our study. However, we did not observe a correlation between the maternal diseases, the state of the newborn, and the transfusional indication.

• Research in Vestibular Science
• /
• v.17 no.4
• /
• pp.134-141
• /
• 2018

Objectives: We aimed to study the role of vestibular input on spatial memory performance in mice that had undergone bilateral surgical labyrinthectomy, semicircular canal (SCC) occlusion and 4G hypergravity exposure. Methods: Twelve to 16 weeks old ICR mice (n=30) were used for the experiment. The experimental group divided into 3 groups. One group had undergone bilateral chemical labyrinthectomy, and the other group had performed SCC occlusion surgery, and the last group was exposed to 4G hypergravity for 2 weeks. The movement of mice was recorded using camera in Y maze which had 3 radial arms (35 cm long, 7 cm high, 10 cm wide). We counted the number of visiting arms and analyzed the information of arm selection using program we developed before and after procedure. Results: The bilateral labyrinthectomy group which semicircular canal and otolithic function was impaired showed low behavioral performance and spacial memory. The semicircular canal occlusion with $CO_2$ laser group which only semicircular canal function was impaired showed no difference in performance activity and spatial memory. However the hypergravity exposure group in which only otolithic function impaired showed spatial memory function was affected but the behavioral performance was spared. The impairment of spatial memory recovered after a few days after exposure in hypergravity group. Conclusions: This spatial memory function was affected by bilateral vestibular loss. Space-related information processing seems to be determined by otolithic organ information rather than semicircular canals. Due to otolithic function impairment, spatial learning was impaired after exposure to gravity changes in animals and this impaired performance was compensated after normal gravity exposure.

• The korean journal of orthodontics
• /
• v.49 no.4
• /
• pp.205-213
• /
• 2019

Objective: The aim of this study was to evaluate the amount of tooth movement and histologic changes with different corticotomy designs and micro-osteoperforation in rabbits. Methods: The sample consisted of 24 rabbits divided into three experimental groups (triangular corticotomy [TC] and indentation corticotomy [IC] with flap, and flapless micro-osteoperforations [MP]) and a control. A traction force of 100 cN was applied by connecting the first premolars to the incisors. The amount of tooth movement was measured. Kruskal-Wallis test was used to assess differences in tooth movement between the groups. Micro-computed tomography, hematoxylin and eosin staining, and tartrate-resistant acidic phosphatase (TRAP) analysis were performed. Analysis of variance was applied to assess differences in TRAP-positive osteoclast count between the groups. Results: The amount of tooth movement increased by 46.5% and 32.0% in the IC and MP groups, respectively, while the bone fraction analysis showed 69.7% and 8.5% less mineralization compared to the control. There were no significant intergroup differences in the number of TRAP-positive osteoclasts. Conclusions: The micro-osteoperforation group showed no significant differences in the amount of tooth movement compared to the corticotomy groups, nor in the TRAP-positive osteoclast count compared to both corticotomy groups and control.

• Korean Journal of Ichthyology
• /
• v.33 no.4
• /
• pp.273-277
• /
• 2021

The feeding habits of the pointhead flounder, Cleisthenes pinetorum were studied in the West Sea in Korea. The samples were investigated using 360 specimens (21.7~48.1 cm in total length) collected by gill net of the coastal waters from January to December 2019. As a result, C. pinetorum consumed mainly Ophiuroidea and Pisces, but also ate small amounts of Macrura, Echinodermata, Amphipoda and Brachyura. The results of this study showed a difference with those of main feed habits of C. pinetorum caught in the coastal waters of Kori (Huh and Baeck, 2003). The proportion of fishes in prey items increased with size-related while that of Ophiuroidea decreased. As total length of C. pinetorum increased the mean number of preys per stomach (mN/ST) and weight of prey per stomach (mW/ST) tended to increase.

• Animal Bioscience
• /
• v.36 no.3
• /
• pp.417-428
• /
• 2023

Objective: Few studies have genetically monitored chickens over time, and no research has been conducted on ducks. To ensure the sustainable management of key duck breeds, we used microsatellite markers to monitor Brown Tsaiya ducks over time genetically. Methods: The second, fourth, sixth to eighth generations of the Brown Tsaiya duck selected for feeding efficiency and control lines were included in this study to investigate the genetic variations, effective population size, population structure and the differentiation between populations over time with 11 microsatellite markers derived from Brown Tsaiya duck. Results: The results showed there were a slight decrease in the genetic variations and an increase in within-population inbreeding coefficient (F_IS) in both lines, but no consistent increase in F_IS was observed in each line. The effective population size in the second and eighth generations was 27.2 for the selected line and 23.9 for the control line. The change in allele richness showed a downward trend over time, and the selected line was slightly lower than the control line in each generation. The number of private alleles (N_p) in the selected line were higher than in the control line. Moderate differentiation was observed between the second and eighth generations in the selected line (F_ST = 0.0510) and the control line (F_ST = 0.0606). Overall, differentiation tended to increase with each generation, but genetic variation and structure did not change considerably after six generations in the two lines. Conclusion: This study provides a reference for poultry conservation and helps to implement cross-generation genetic monitoring and breeding plans in other duck breeds or lines to promote sustainable management.

• Journal of Korean Society on Water Environment
• /
• v.39 no.2
• /
• pp.181-193
• /
• 2023

Distribution changes in microalgae communities were studied in the Nakdonggang River at two sampling stations (St.1 Gyeongcheongyo Bridge (GB) and St.2 Daedong Wharf (DW)) at monthly intervals from January 2021 to November 2021. A total of 83 taxa included 82 species, 1 forma, belonging to 49 genera, 32 families, 21 orders, and 8 classes. The most important groups were Bacillariophyta and Chlorophyta. The number of species ranged from 5 to 24 in GB, and from 9 to 21 taxa in DW. The contribution of Bacillariophyta to the total species richness was the highest during all survey periods, and Chlorophyta yielded the next highest value in the study area. The dominant taxa were Aulacoseira ambigua, A. ambigua f. japonica, and Ulnaria acus in this study. Cluster analysis and non-metric multidimensional scaling (nMDS) analysis based on Bray- Curtis similarity identified 4 major groups, which corresponded to microalgae assemblages and their characteristic species. Correlation was analyzed through the CCA analysis. It was found that there was a correlation between the microalgae and environmental factors. It was revealed that the divided groups were distinguished because of the differences by the survey period. Therefore, seasonal change was judged as a major factor affecting the distribution of microalgae communities.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.36 no.5
• /
• pp.513-519
• /
• 2023

It was reported that a tetragonal phase can be stabilized with maintaining good piezoelectric properties when Na_0.5K_0.5NbO₃ (KNN) is modified with 0.06 mol SrTiO₃. However, such a high amount of SrTiO₃ leads not only to poor sinterability but low Curie temperature (T_C). To maintain high TC with good piezoelectric properties in KNN-based lead-free piezoelectric ceramics, this study investigates the effect of Li-doping on the dielectric and piezoelectric properties of 0.96Na_0.5K_0.5NbO₃-0.04SrTiO₃ (KNN-4ST) ceramics. As a result, the orthorhombic-tetragonal phase transition was observed at 2 mol% Li₂CO₃ modified KNN-4ST ceramics, whose T_C, d₃₃ and k_p values are 328℃, 165pC/N and 0.33, respectively.

• Journal of the Korean Society of Physical Medicine
• /
• v.17 no.2
• /
• pp.53-62
• /
• 2022

PURPOSE: This study was conducted to investigate the effect of a real-time pressure feedback provided during gait training on the weight weight distribution of the inner part of mid-foot in paralyzed side and gait function in stroke patients. METHODS: A total of 24 patients with hemiplegic stroke in a rehabilitation hospital were randomly assigned to the experimental and control group. All participants (n = 24) performed 15 min of comprehensive rehabilitation therapy 5 times a week for a period of 4 weeks. Additionally, the experimental group and control group underwent gait training with a real time feedback and general gait training, respectively, for 15 min five times a week for 4 weeks. Weight distribution and gait function were measured before and after the 4-week training. RESULTS: Significant increases in the weight distribution (WD), stance time (ST) and step length (SL) of the paralyzed side, and a significant decrease in the 10 m walking test (10 MWT) observed after training in the two groups (p < .05). The experimental group showed larger changes in the all variables than the control group (WD, +10.5 kg vs. +8.8 kg, p < .05; ST, 12.8 s vs. 4.9 s, p < .05; SL, 4.9 cm vs. 1.7 cm, p < .05; 10 MWT, -3.5 s vs. -1.0 s, p < .05, respectively). CONCLUSION: Gait training with a real-time feedback might be effective in improving the normalization of weight bearing of the paralyzed lower extremity and gait function of stroke patients, and be considered to be a more effective gait training for improving the abilities than the general gait training.