• Applied Microscopy
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• v.46 no.4
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• pp.238-243
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• 2016

Twinning-induced plasticity (TWIP) steels with the austenite structure containing high manganese exhibit both good strength and excellent formability. Such properties originate from crystallographic slip and mechanical twins produced when the austenite structure is under mechanical stress. There are 12 twin systems, referred to as twin variants, when slip is induced. These twin systems include twin planes and twin directions and play an important role in determining strength and ductility of the material by strongly influencing texture formation of the austenite structure. In the present study, twins produced in a high-Mn TWIP steel as a result of uniaxial tension were observed using a transmission electron microscope; a comparative analysis was performed through interaction energy calculations. Electron diffraction was used to determine the twin system with respect to the uniaxial tension direction in each grain. Both the Schmid factors and interacting energies required for the generation of twins were calculated and subsequently compared with experimental results. This approach demonstrated the possibility of predicting the deformation behavior of the material.

• The Transactions of the Korea Information Processing Society
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• v.13 no.2
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• pp.26-33
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• 2024

There has been a recent surge of interest in the Digital Twin technology. The Digital Twin is technique for optimizing objects by simulating physical phenomena or objects through computer-based simulations. Currently, single Digital Twin is being developed to optimize processes limited to specific fields, but there is a limitation in that the independent Digital Twins cannot analyze the vast and complex processes of the real world. To overcome this, the concept of federated Digital Twin has been introduced. To date, the federated Digital Twin research has primarily focused on how to optimize macroscopic objects such as cities. However, by leveraging the interconnected nature of twins, existing implementations of the single Digital Twins can be modularized. In this study, we define the concepts and interrelationships of the single Digital Twin and the federated Digital Twin from a functional perspective related to process optimization and design a modularization technique for the single Digital Twin using the federated Digital Twin. Furthermore, this study aims to discuss the proposed methodology's efficacy by designing a model applying modularization to a real-world fabric manufacturing case.

• Clinical and Experimental Pediatrics
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• v.46 no.3
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• pp.224-229
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• 2003

Purpose : To examine various neonatal outcomes and perinatal factors resulting from assisted reproduction compared to that of spontaneous conception. Methods : This is a retrospective study. The control cases were all twins of spontaneous conception born between periods from January 1995 to June 2000. The study cases were identified from twins conceived by assisted reproduction in the same time peried. A total of 460 sets of twins consisted of 250 twins of spontaneous conception and 156 twins of assisted reproduction were studied. The primary outcomes were neonatal morbidity and mortality and the secondary outcomes were perinatal factors including number, length and cost of hospitalization for the delivery. Results : No differences were seen in various neonatal factors including gestational age, birth weight and incidences of respiratory distress syndrome, patent ductus arteriosus, necrotizing enterocolitis, hyperbilirubinemia, sepsis, intraventricular hemorrhage and the length of hospitalizations. Lower one minute and five minute Apgar scores and frequently encountered electrolyte abnormalities were observed in neonates of assisted reproduction. In general, the second twin of assisted reproduction had increased incidences of respiratory distress syndrome, sepsis and necrotizing enterocolitis than the first twin. Increased frequencies of preterm labor, hospitalization and elective cesarean section were seen among mothers who underwent artifical conception. However, overall hospital costs in terms of mothers hospitalization for the delivery and neonates hospitalization did not show differences. Conclusion : Assisted reproduction twins had similar neonatal morbidities, mortalities and perinatal morbidities compared to those born by spontaneous conception.

• Clinical and Experimental Pediatrics
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• v.45 no.12
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• pp.1512-1518
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• 2002

Purpose : Twins have a higher mortality and morbidity than singletons. Co-twin with one fetal death is particularly at risk. We investigated the neonatal outcome of live co-twins when one fetus had died after the 20th gestational week, and associated risk factors. Methods : A retrospective study was performed in fifteen cases of twin pregnancy with single intrauterine fetal deaths after the 20th gestational week during the period from January 1996 to December 2000 at Chonnam University Hospital. Results : Gestational age was $33.7{\pm}3.2weeks$, birth weight was $1,992{\pm}592g$. Interval between one fetal death being detected and the delivery of a live co-twin was $32.4{\pm}29.5days$. There were 11 cases(73.3%) of premature babies less than 37 gestational weeks. Main causes of preterm delivery were preterm labor and premature rupture of membranes. Hematologic findings suggesting disseminated intravascular coagulopathy(DIC) were not found in all mothers before delivery, and was not associated with DIC and encephalomalacia of the live co-twin. Perinatal outcome of fifteen live co-twins was as follows : six were normal(40%), three were DIC(20.0%), three were encephalomalacia(20.0%), one suffered intrauterine growth retardation, there was one case of twin to twin transfusion syndrome, and one of congenital heart disease(atrial septal defect with pulmonary stenosis). The occurrence of DIC and encephalomalacia in live co-twins was not related to placental chorionicity, birth weight, gestational week, and the interval between the detection one fetal death and the delivery of a live co-twin. Conclusion : We could not find any maternal hematologic problems in twin pregnancies complicated by one fetal death. Twenty percent of live co-twins showed DIC and encephalomalacia. However, its associated risk factors were not found. We need to investigate more closely the cases of live co-twins with one intrauterine fetal death.

• Journal of Convergence for Information Technology
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• v.10 no.9
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• pp.1-7
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• 2020

In order to implement a smart factory for manufacturing innovation, more digital twins will be developed and applied gradually. In particular, simulation and optimization of digital twins makes it possible to support critical decision-making like a predictive maintenance of the equipment for manufacturing. In terms of a user perspective, this study suggests the conceptual framework of Digital Twin Management System (DTMS) for supporting the analytical and managerial activities for Digital Twins. We integrate the methods and structure of the area like Manufacturing Engineering, Decision Support Systems, and Optimization for developing the DTMS. The framework suggested in this study shows a typical DSS which consists of dialog management system, model management system and data management system. It also includes Analytical Digital Twins and simulations & optimization module. The framework is being applied in one of the most competitive and complex industrial sector. Also this study is meaningful to suggest a new direction of research.

• Clinical and Experimental Reproductive Medicine
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• v.34 no.3
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• pp.173-178
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• 2007

Objective: To compare the outcome of twin pregnancies after in-vitro fertilization (IVF) with that of spontaneously conceived twins. Methods: We analyzed 146 twins retrospectively, who had been delivered between January 2000 and July 2005. After reviewing their obstetric medical records, 72 twins conceived with IVF (IVF group) and 51 spontaneously conceived twins (spontaneous group), whose gestational age was over 24 weeks, were recruited for this study. Results: There were no significant statistical differences of demographic features such as maternal age, gestational age and fetal weight between the two groups. However, the risk of pregnancy-induced hypertension (PIH) and gestational diabetes (G-DM) had significantly increased in the group of IVF (OR 2.59; 95% CI 1.01$\sim$6.66). The risk of fetal weight discordancy rate (>20%) and fetal-sex homology rate in IVF group were decreased (OR 0.37; 95% CI 0.14$\sim$0.96, OR 0.45; 95% CI 0.21$\sim$0.99). Conclusion: In this comparative study, maternal PIH and G-DM risks of IVF group are higher than that of spontaneous group. But, fetal-weight discordancy risk and fetal-sex homology rate were lower in IVF group.

• The Journal of Engineering Geology
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• v.8 no.1
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• pp.75-86
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• 1998

Eighteen oriented samples from the Jeongsun limestone of the Joseon Supergroup are collected. The orientations of C-axis of calcite and e twin plane, the average thickness, numbers of twins and the widths of calcite grains in 10 samples are measured. Then, the twin strain, mean width, intensity of twin and relative magnitude and orientations of principal stresses are calculated using Calcite Strain Gauge program. Twin strain, mean width and intensitv rainge between 0.801%~10.927%, $0.43{\mu\textrm{m}}~2.03{\mu\textrm{m}}$, and 33.5~113.4twim/mm, respectively. Metamorphic temperatures calculated from twin show below $70^{\circ}C$, indicating that twins were developed within 2.3km depth. In five samples, two events with different orientations of principal stress produced calcite twins, while only one event produced calcite twins in five samples. The direction of the maximum stress is almost horizontal and the minimum is almost vertical, indicating that the stress regirne is identical with thrust fault. E-W and NW-SE are the most dominant directions of comressive stress and N-S and NE-SW directions are also shown. Comparision between paleostress orientations measured in the study and others indicates that the maximum horizontal stress oriented to E-W may represent the paleostress of period either from the Silurian to the Triassic or from the Silulian to the Permian. Paleostress oriented to NW-SE may be the major direction of stress during the Daeho orogeny.

• Korean Journal of Crystallography
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• v.2 no.1
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• pp.1-11
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• 1991

When GaAs single crystals are grown by LEC method, a serious problem is that longitudinal twins are often generated. the growth axis is changed from (100) to (221) direction by logitudinal twin. In this experiment, 3 inch GaAs single crystals, slaving (100) uonh axis, were von by LEC method. Striations and edge facets generated during crystal growth, were observed by SPW photo-etching. Relationship between striations and edge facets was studied. Instability of their generation was the cause of goneration of longitudinal twins. The shape of striations was changed with the growth conditions such as crystal diameter and melt volume. In the region of crystal edge: there was the microscopic fluctuation by the instability of melt convection. Edge facets consisting of {111} plane developed well in the region which striation were convex to the melt. Because the angle between striation and {111} edge facet decreased in that region. Longitudinal twins were generated on the crystal surface at the <111> direction which is perpendicular to the growth axis. These were generated by unstable melt convection and propagated in the crystal as crystal grew. Longitudinal twins were generated when regrowth rate was very fast after {111} edge facets were remelted. So, in order to supress the generation of longitudinal twin, abrupt change of melt convection must be prohibited.

• 대한예방의학회:학술대회논문집
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• 2001.10a
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• pp.316-316
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• 2001

• 한국정보디스플레이학회:학술대회논문집
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• 2001.08a
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• pp.13-21
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• 2001

Increased investment costs for larger substrate factories require breakthrough efficiencies and the capture of price premiums. Otherwise, their profit indicators will fall below those of prior plant investments. Market factors inhibit the continued expansion of monitor size and resolution, so a television market must be developed if substrate size increases will remain profitable, long term.