• Nuclear Engineering and Technology
• /
• v.52 no.10
• /
• pp.2262-2273
• /
• 2020

Digital twin technology can provide significant value for the prognostics and health management (PHM) of critical plant components by improving insight into system design and operating conditions. Digital twinning of systems can be utilized for anomaly detection, diagnosis and the estimation of the system's remaining useful life in order to optimize operations and maintenance processes in a nuclear plant. In this regard, a conceptual framework for the application of digital twin technology for the prognosis of Control Element Drive Mechanism (CEDM), and a data-driven approach to anomaly detection using coil current profile are presented in this study. Health management of plant components can capitalize on the data and signals that are already recorded as part of the monitored parameters of the plant's instrumentation and control systems. This work is focused on the development of machine learning algorithm and workflow for the analysis of the CEDM using the recorded coil current data. The workflow involves features extraction from the coil-current profile and consequently performing both clustering and classification algorithms. This approach provides an opportunity for health monitoring in support of condition-based predictive maintenance optimization and in the development of the CEDM digital twin model for improved plant safety and availability.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2021.10a
• /
• pp.253-258
• /
• 2021

With the 4th Industrial Revolution and the development of technology, markets of the VR&AR have increased. Also due to COVID-19 pandemic, demands for a digital environment were required because of physical space constraints. Firms are trying to solve this problem by using Metaverse platforms. However, with markets such as Metaverse, VR, AR, and Digital Twins are expanding, prior research on Metaverse definition or classification system is insufficient. Based on understanding VR&AR, Digital Twin, this study established a Industry-Service classification for Metaverse by defining Case studies on Metaverse and through prior research. And by Industry-Service classification for Metaverse this paper propose Metaverse Industry-Service Matrix to analyze the trend and possibility of Metaverse Platform

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.18 no.1
• /
• pp.15-29
• /
• 2024

A fetoscope is an optical endoscope, which is often applied in fetoscopic laser photocoagulation to treat twin-to-twin transfusion syndrome. In an operation, the clinician needs to observe the abnormal placental vessels through the endoscope, so as to guide the operation. However, low-quality imaging and narrow field of view of the fetoscope increase the difficulty of the operation. Introducing an accurate placental vessel segmentation of fetoscopic images can assist the fetoscopic laser photocoagulation and help identify the abnormal vessels. This study proposes a method to solve the above problems. A novel encoder-decoder network with a dual-path structure is proposed to segment the placental vessels in fetoscopic images. In particular, we introduce a channel attention mechanism and a continuous convolution structure to obtain multi-scale features with their weights. Moreover, a switching connection is inserted between the corresponding blocks of the two paths to strengthen their relationship. According to the results of a set of blood vessel segmentation experiments conducted on a public fetoscopic image dataset, our method has achieved higher scores than the current mainstream segmentation methods, raising the dice similarity coefficient, intersection over union, and pixel accuracy by 5.80%, 8.39% and 0.62%, respectively.

• Journal of Preventive Medicine and Public Health
• /
• v.46 no.1
• /
• pp.50-60
• /
• 2013

Objectives: This study aimed to evaluate whether the birth rate is associated with socioeconomic status in the women of the Republic of Korea, where the birth rate is rapidly decreasing. Methods: This study included 732 females from the Healthy Twin Study, a family-twin cohort. The participants were classified into 3 socioeconomic groups according to their average income, education, and occupation. The association between socioeconomic status and number of children was assessed using gamma regression analysis with a generalized linear mixed model, adjusting for the age group, smoking/alcohol status, and family relationships. Results: The group with the highest education level had significantly fewer children compared with the group with the lowest education level (p=0.004). However, no significant associations were found according to household income level. The non-manual labor group had significantly fewer children compared with those working as homemakers (p=0.008). Conclusions: This study aimed to explain the causal relationship between socioeconomic status and number of children. Associations between some socioeconomic status and number of children were found in Korea.

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

• Korea-Australia Rheology Journal
• /
• v.13 no.2
• /
• pp.89-95
• /
• 2001

Effects of particulate size and frictional characteristics were examined on the melting behavior of PP(polypropylene) in a twin screw extruder. Powder and pellet types of PP were used and each component was blended with PE(polyethylene) wax and clay, respectively. It was observed that small size particulates, 1.e. powder systems exhibit accelerated melting behavior; and it was also found that the abrasive auditive acts as an effective agent for fast melting of PP powder. Retardation of melting due to the reduced friction was observed in both types of PP, contrary to the result found in a batch mixer. The tendency observed in variation of torque and exit temperature was explained in terms of frictional effect and length of compacted region formed during evolution of melting.

• Proceedings of the KIEE Conference
• /
• 2008.04b
• /
• pp.200-202
• /
• 2008

The oscillation is very dangerous in bundled transmission lines, especially 345kV 4 bundle transmission lines are very weak for subspan oscillations. In some cases, subspan oscillations are continuously occurred in the same subspan. In order to develop the control method of the above subspan oscillation, this paper suggests a method of applying twin spacers to the subspans. We have carried out some tests to analyze the oscillation phenomena after installing twin spacers on 34sky real lines, and we got a good effect for controling subspan oscillations.

• 한국연소학회:학술대회논문집
• /
• 2004.06a
• /
• pp.248-255
• /
• 2004

For the compactness of regenerative combustion, self regenerative combustion and embedding regenerator inside furnace are proposed. The Self Regenerative burner system was developed to enhance thermal efficiency and Low Nox emission. In the twin regenerative system, two burner heads are generally used for preheating and exhausting combustion mode. But self regenerative burner system use only single nozzle body for regenerative combustion. Also two kind of regenerator, internal and external type, were designed to operate conveniently in both large and small furnace. According to test result, the self regenerative combustion system gives strong internal exhaust gas recirculation that reduce NOx emission significantly. NOx was measured as 50ppm(5% O2, 1290C furnace temperature). Also it is found that the fuel saving rate due to the self regenerative burner system reach to 30-40%. Thus it can be concluded that self regenerative mild combustion system appears to provide a reasonable regenerative burner for compactness and high performance as compared with conventional twin regenerative burner system. Also in the RT Application , compact twin regenerative burner was developed with the help of embedding regenerator inside furnace.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.23 no.1
• /
• pp.12-24
• /
• 1999

A computer program has been developed for analyzing the two-dimensional, unsteady conservation equations for transport phenomena in the molten region of twin-roll continuous casting in order to predict the turbulent velocity, temperature fields, and solidification process of the molten steel. The energy equation of the cooling roll is solved simultaneously with the conservation equations of molten steel in order to consider heat transfer through the cooling roll. The results show the velocity, temperature and solidification pattern in the molten region with roll temperature as a function of time. The results for velocity and temperature fields with solidification are compared with those without solidification, giving different thermofluid characteristics in the molten region. We also investigated the effects of revolutional speed of roll, superheat and nozzle geometry on the turbulent flow, temperature and solidification in the molten steel and temperature fields in the cooling roll.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2008.03a
• /
• pp.181-188
• /
• 2008

In this study, estimation of behavioral characteristics between twin tunnels was performed through the series of laboratory experiment on the small scale tunnel model. In the model test, the experimental parameters were geological conditions, center to center distance between twin tunnels, application of discontinuous inclination. To estimated behavior of pillar and load-displacement relationship by model tests and numerical analyses.