• Perinatology
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• v.29 no.4
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• pp.159-164
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• 2018

Objective: To compare neonatal respiratory morbidity of twins according to birth order related to gestational age and mode of delivery. Methods: We performed the retrospective research of the medical records of 3,224 neonates (1,612 twin pairs) born in a single center from January 2011 to December 2015. Subjects were classified into four gestational age groups: very (<32 weeks), moderate (32-33 weeks), late (34-36 weeks) preterm, and term (${\geq}37weeks$) groups. We investigated clinical characteristics and respiratory morbidity according to birth order related to gestational age group and mode of delivery. Results: We found increased risk of respiratory morbidity in second-born twin than first-born twin (P=0.039). Second-born twin was associated with increased risk of respiratory distress syndrome (RDS) in late preterm group (odds ratio [OR] 2.8, 95% confidence interval [CI] 1.30-5.95), and transient tachypnea of newborn in term group (OR 1.4, 95% CI 1.03-1.81). In vaginal delivery mode, there was no difference of respiratory morbidity between first and second-born twin in each group, but in cases of Cesarean delivery, second-born twin was related with a greater risk of RDS in late preterm group (OR 2.3, 95% CI 1.07-5.09). Birth order and Cesarean section independently increased the risk of RDS (adjusted OR [aOR] 1.69, 95% CI 1.12-2.54; aOR 2.14, 95% CI 1.25-3.66, respectively). Conclusion: Second-born twin and Cesarean delivery are associated with increased risk of RDS, especially in late preterm twins.

• Smart Media Journal
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• v.9 no.4
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• pp.109-117
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• 2020

Recently, with the advent of the 4th industrial revolution, digital twins are emerging as an important technology that connects and integrates physical systems and cyber systems. In this article, we analyzed the major requirements of digital twins required for the construction of digital twins of power equipments in the energy field, focusing on the industry 4.0-based Asset Administration Shell(AAS). However, since not so many studies have been conducted yet on a common platform or demonstration model for implementing digital twins both domestically and internationally, digital twin requirements are analyzed with the consideration of digital twinning of power equipment in the energy field. Also, we suggested necessary procedures and specific functions of AAS to establish a smart energy digital twin in the future by analyzing the core requirements necessary for the construction and designing the AAS design for specific power equipment.

• Clinical and Experimental Pediatrics
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• v.50 no.2
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• pp.182-189
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• 2007

Purpose : The primary purpose of this study was to evaluate the growth and neuropsychologic function following treatments for pediatric hematologic and oncologic diseases. Healthy monozygotic twins served as ideal controls for comparison to exclude possible confounding factors. Methods : Seven children treated with various hematologic and oncologic diseases were included in the study: acute lymphoblastic leukemia (ALL; n=2), Diamond-Blackfan anemia twins (n=2), and aplastic anemia (n=3). The median age at the diagnosis was 5.2 (0.3-15) years. The median duration of follow-up was 7.2 (4.9-10) years. Controls were healthy monozygotic twins. Growth was measured and the percentile channels were evaluated sequentially for patients. The K-WISC III was applied and compared in 5 pairs of patients and controls. Results : Similar growth profiles were noted for the twins. The percentiles at diagnosis was 3-10 in 3, 25-50 in 2, and 50-75 in 2 cases. All patients stayed in their growth percentiles through follow-up, except for 1 patient who became obese. For IQ tests, the mean behavioral, verbal and full scale IQ scores of patients were 88.0, 93.8, and 89.8, respectively, and those from their corresponding controls were 92.2, 97.0, and 91.7 (P>0.05). However, 2 children who were treated for ALL had lower IQ scores. Conclusion : Similar growth profiles were observed in the monozygotic twins in terms of height and weight. The IQ scores of patients were similar to those of monozygotic twins. However, prophylactic CNS-directed therapy for leukemia might adversely affect the IQ scores. A further prospective study on larger number of twins is warranted.

• Korean Journal of Veterinary Research
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• v.59 no.4
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• pp.181-185
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• 2019

The traditional calculation of gestation length (GL) in Holstein cows relies solely on the insemination day and has a high error rate for actual calving dates. The present study was conducted to develop a more accurate method of estimating GL. Among 3,578 Holstein cows, the number of fetuses had a significant (p < 0.05) effect, with GLs of 282.4 ± 2.5 days for singletons and 276.0 ± 1.6 days for twins. Within the singleton group, the GLs were 284.6 ± 1.9 days for males and 280.3 ± 1.5 days for females, a significant difference (p < 0.05). However, within the twin group, there was no difference in GLs among twin males, twin females, or twins of both sexes. Gestation was significantly shorter for singleton males born from June to August but significantly longer for twin males born in the May to June period (p < 0.05). Neither parity nor housing type was associated with any significant difference in GL. In order to predict the calving dates of Holstein cows accurately and improve their management, calculations should consider the number and sex of fetuses as well as the insemination season.

• Journal of the Korean Society for Heat Treatment
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• v.11 no.4
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• pp.274-282
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• 1998

The effect of Al addition on the fatigue properties of austenitic Fe-25Mn-Al-0.5C steels was studied. When Al was not added to the Fe-25Mn 0.5C steel, the strain induced ${\varepsilon}$ martensites, deformation twins and slip bands were formed during fatigue deformation. When 2wt% of Al was added to the steel, the deformation twins and slip bands were formed during fatigue deformation. When 5wt% of Al was added, only slip bands were formed. In low cycle fatigue test, the alloys containing 0wt% and 2wt%Al showed the cyclic hardening due to ${\varepsilon}$ martensites and deformation twins, resulting in shorter fatigue lives than the alloy containing 5wt%Al. In fatigue crack propagation test, the alloy without Al showed the highest crack propagation rate. The fracture surface of the alloy without Al was flat, whereas that of the alloy with 2% or 5%Al was rough. The ${\Delta}K_{th}$, values of the alloys with 0%, 2% and 5%Al were 16, 17.5, and $20.5MPam^{1/2}$, respectively.

• Imaging Science in Dentistry
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• v.42 no.2
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• pp.95-97
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• 2012

The styloid process is a cylindrical, long cartilaginous bone located on the temporal bone. The calcified stylohyoid ligament and elongated styloid process can be identified radiographically, and they are associated with a number of syndromes and symptoms. The exact cause of the styloid process elongation due to calcification and subsequent ossification of ligament is unclear. This report presents a case of severely calcified stylohyoid ligament complex occurred in twins who have the same pattern of calcification.

• The korean journal of orthodontics
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• v.49 no.1
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• pp.3-11
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• 2019

Objective: The purpose of this study was to investigate the influence of heritability on the craniofacial soft tissue cephalometric characteristics of monozygotic (MZ) twins, dizygotic (DZ) twins, and their siblings (SIB). Methods: The samples comprised Korean adult twins and their siblings (mean age, 39.8 years; MZ group, n = 36 pairs; DZ group, n = 13 pairs of the same gender; and SIB group, n = 26 pairs of the same gender). Thirty cephalometric variables were measured to characterize facial profile, facial height, soft-tissue thickness, and projection of nose and lip. Falconer's method was used to calculate heritability (low heritability, $h^2$ < 0.2; high heritability, $h^2$ > 0.9). After principal components analysis (PCA) was performed to extract the models, we calculated the intraclass correlation coefficient (ICC) value and heritability of each component. Results: The MZ group exhibited higher ICC values for all cephalometric variables than DZ and SIB groups. Among cephalometric variables, the highest ${h^2}_{(MZ-DZ)}$ and ${h^2}_{(MZ-SIB)}$ values were observed for the nasolabial angle (NLA, 1.544 and 2.036), chin angle (1.342 and 1.112), soft tissue chin thickness (2.872 and 1.226), and upper lip thickness ratio (1.592 and 1.026). PCA derived eight components with 84.5% of a cumulative explanation. The components that exhibited higher values of ${h^2}_{(MZ-DZ)}$ and ${h^2}_{(MZ-SIB)}$ were PCA2, which includes facial convexity, NLA, and nose projection (1.026 and 0.972), and PCA7, which includes chin angle and soft tissue chin thickness (2.107 and 1.169). Conclusions: The nose and soft tissue chin were more influenced by genetic factors than other soft tissues.

• Journal of the Korean Society for Heat Treatment
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• v.30 no.6
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• pp.258-263
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• 2017

The effect of cooling rate on the damping capacity of pure Mg was studied. Two Mg samples with different cooling rates were prepared by heat treatment at 873 K for 24 h, followed by water quenching and by furnace cooling to room temperature, respectively. The average grain sizes of the Mg samples were almost identical regardless of the cooling rate, but more twins were observed in the sample with faster cooling rate. The calculated vacancy fraction was higher in the fast cooling sample than the slow cooling one. It is noted that the fast cooling sample exhibited lower damping capacity both in the strain-amplitude independent and strain-amplitude dependent regions. Higher values of vacancy concentration and number density of twins in the fast cooling sample are considered to be responsible for the deteriorated damping capacity in the strain-amplitude independent and strain-amplitude dependent regions, respectively.

• Journal of the Korean Society for Heat Treatment
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• v.7 no.4
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• pp.277-287
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• 1994

The effect of grain size on the tensile properties and fatigue behavior of austenitic high Mn steel has been investigated. The recrystallized austenite grain size of the cold rolled high Mn steel was increased as the annealing temperature increased from $600^{\circ}C$ to $1000^{\circ}C$. Larger austenite grain size decreased the yield strength and the tensile strength, and increased the uniform elongation due to transformation of some austenite into twins or E-martensite phase during deformation. Austenite grain refinement increased the tendency to form dislocation cells, instead. The specimen annealed at $1000^{\circ}C$ with large grain size showed lower fatigue crack propagation rate in low ${\Delta}K$ region due to rougher fracture surface caused by formation of deformation twins during fatigue at the crack tip region.

• Transactions of Materials Processing
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• v.19 no.7
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• pp.416-422
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• 2010

The $\{10\bar{1}2\}$ twinning characteristics, such as active twin variants, volume fraction of twins with strain, twin morphology, twin texture and angle relationship between twins, were dependent on the activation mode (i.e., tension parallel to the caxis or compression perpendicular to the c-axis). The selection criterion of active twin variants was governed by the Schmid law. This activation of selected twin variants depending on the activation mode consequently caused a totally different plastic deformation behavior in two activation modes. The differences in the deformation characteristics, such as flow stress and work hardening rate, between both activation modes were explained in relation with activation stresses for slips and twinning, relative activities of twinning and slips during plastic deformation, grain refining effect by twin boundaries (Hall-Petch effect), and twinning-induced change in activities of slips.