• Journal of the Earthquake Engineering Society of Korea
• /
• v.28 no.4
• /
• pp.223-231
• /
• 2024

For the OPR1000, a standard power plant in Korea, an analytical model of the containment building considering voids and deterioration was built with multilayer shell elements. Voids were placed in the vulnerable parts of the analysis model, and the deterioration effects of concrete and rebar were reflected in the material model. To check the impact of voids and deterioration on the seismic performance of the containment building, iterative push-over analysis was performed on four cases of the analytical model with and without voids and deterioration. It was found that the effect of voids with a volume ratio of 0.6% on the seismic performance of the containment building was insignificant. The effect of strength reduction and cross-sectional area loss of reinforcement due to deterioration and the impact of strength increase of concrete due to long-term hardening offset each other, resulting in a slight increase in the lateral resistance of the containment building. To determine the limit state that adequately represents the seismic performance of the containment building considering voids and deterioration, the Ogaki shear strength equation, ASCE 43-05 low shear wall allowable lateral displacement ratio, and JEAC 4601 shear strain limit were compared and examined with the analytically derived failure point (ultimate point) in this study.

• Nuclear Engineering and Technology
• /
• v.54 no.6
• /
• pp.2297-2310
• /
• 2022

A condensation heat transfer model is essential to accurately predict the performance of the passive containment cooling system (PCCS) during an accident in an advanced light water reactor. However, most of existing models tend to predict condensation heat transfer very well for a specific range of thermal-hydraulic conditions. In this study, a new correlation for condensation heat transfer coefficient (HTC) is presented using machine learning technique. To secure sufficient training data, a large number of pseudo data were produced by using ten existing condensation models. Then, a neural network model was developed, consisting of a fully connected layer and a convolutional neural network (CNN) algorithm, DenseNet. Based on the hold-out cross-validation, the neural network was trained and validated against the pseudo data. Thereafter, it was evaluated using the experimental data, which were not used for training. The machine learning model predicted better results than the existing models. It was also confirmed through a parametric study that the machine learning model presents continuous and physical HTCs for various thermal-hydraulic conditions. By reflecting the effects of individual variables obtained from the parametric analysis, a new correlation was proposed. It yielded better results for almost all experimental conditions than the ten existing models.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.36 no.3
• /
• pp.155-163
• /
• 2023

Real-time monitoring technology is critical for ensuring the safety and reliability of nuclear power plant structures. However, the current seismic monitoring system has limited system identification capabilities such as modal parameter estimation. To obtain global behavior data and dynamic characteristics, multiple sensors must be optimally placed. Although several studies on optimal sensor placement have been conducted, they have primarily focused on civil and mechanical structures. Nuclear power plant structures require robust signals, even at low signal-to-noise ratios, and the robustness of each mode must be assessed separately. This is because the mode contributions of nuclear power plant containment buildings are concentrated in low-order modes. Therefore, this study proposes an optimal sensor placement methodology that can evaluate robustness against noise and the effects of each mode. Indicators, such as auto modal assurance criterion (MAC), cross MAC, and mode shape distribution by node were analyzed, and the suitability of the methodology was verified through numerical analysis.

• Journal of The Korea Institute of Healthcare Architecture
• /
• v.24 no.1
• /
• pp.51-58
• /
• 2018

Purpose: In this study, through the comparison of the pressure fluctuation and air exchange volume in negative isolation room according to the type of the door and door opening/closing speeds, which is one of the main factors causing the cross contamination of the negative pressure isolation room, establishes standard operating procedures to prevent cross contamination in high risk infectious diseases and isolation room design. Methods: In this study, the air flow each of the room is analyzed using ANASYS CFX CODE for flow analysis. In addition, the grid configuration of the door is constructed by applying Immersed Solid Methods. Results: The pressure fluctuation due to the opening and closing of the hinged door was very large when the moment of the hinged door opened and closed. Especially, at the moment when the door is closed, a pressure reversal phenomenon occurs in which the pressure in the isolation room is larger than the pressure in the anteroom. On the other hand, the pressure fluctuation due to the opening and closing of the sliding door appeared only when the door was closed, but the pressure reversal phenomenon not occurred at the moment when the sliding door was closed, unlike the hinged door. As the opening and closing speed of the hinged door increases, the air exchange volume is increased. However, as the opening and closing speed of the sliding door is decreased, the air exchange volume is increased. Implications: According to the results of this study, it can be concluded that the pressure fluctuation due to the opening and closing of the hinged door is greater than the pressure fluctuation due to the opening and closing of the sliding door. In addition, it can be confirmed that the pressure reversal phenomenon, which may cause to reduce the containment effect in negative pressure isolation room, is caused by the closing of the hinged door. Therefore, it is recommended to install a sliding door to maintain a stable differential pressure in the negative isolation room. Also, as the opening and closing speed of the hinged door is slower and the opening and closing speed of the sliding door is faster, the possibility of cross contamination of the room can be reduced. It is therefore necessary to establish standard operating procedures for negative isolation room for door opening and closing speeds.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.37 no.12
• /
• pp.1547-1557
• /
• 2013

A forced vibration model of a rail system was established using the Timoshenko beam theory to determine the dynamic response of a rail under time-varying load considering the damping effect and stiffness of the elastic foundation. By using a Fourier series and a numerical method, the critical velocity and dynamic response of the rail were obtained. The forced vibration model was verified by using FEM and Euler beam theory. The permanent deformation of the rail was predicted based on the forced vibration model. The permanent deformation and wear were observed through the experiment. Parametric studies were then conducted to investigate the effect of five design factors, i.e., rail cross-section shape, rail material density, rail material stiffness, containment stiffness, and damping coefficient between rail and containment, on four performance indices of the rail, i.e., critical velocity, maximum deflection, maximum longitudinal stress, and maximum shear stress.

• Proceedings of the Korean Society of Plant Biotechnology Conference
• /
• 2005.11a
• /
• pp.367-370
• /
• 2005

The risk from genetically modified (GM) plants results from the possibility of gene contamination producing adverse effects on biological diversity by introducing herbicide or insect resistance into related plants or weeds (NAS 2002). The concern about the leakage of genes from GM plants into the environment has primarily focused on pollen that could be wind-borne for long distances. During the period of fisk assessment in Japan, physical containment is applied as a measure of reducing gene flow via the dispersal of pollen from GM plants into the surrounding environment In this study, we tried to estimate the effect of physically contained greenhouse covered by 1-mm fine mesh to reduce pollen dispersal by researching cross pollination rate between non-GM yellow maize in a greenhouse and silver maize outside the greenhouse.

• Journal of Advanced Navigation Technology
• /
• v.28 no.1
• /
• pp.21-26
• /
• 2024

Urban air mobility (UAM) is being considered as an alternative to transportation in urban areas where traffic congestion is increasing. It is judged that it will be difficult to manage the complex UAM operation environment with the existing Air Traffic Service, which is a person-centered service. Therefore, an advanced information processing-based traffic management system for UAM (UATM) is needed. Airspace management is essential to establish a systematic UAM traffic management (UATM) environment. In particular, the establishment of exclusive corridors where UAM aircraft can operate safely can provide opportunities to operate UAM aircraft without violating the minimum flight altitude regulations. This study conducted an empirical analysis using a helicopter of similar size to UAM to establish the cross-track dimension of the corridor for UAM operation. The research results can be used as a guideline when designing UAM corridors.

• Nuclear Engineering and Technology
• /
• v.46 no.3
• /
• pp.439-446
• /
• 2014

An amphibious inspection robot system (hereafter AIROS) is being developed to visually inspect the in-containment refueling storage water tank (hereafter IRWST) strainer in APR1400 instead of a human diver. Four IRWST strainers are located in the IRWST, which is filled with boric acid water. Each strainer has 108 sub-assembly strainer fin modules that should be inspected with the VT-3 method according to Reg. guide 1.82 and the operation manual. AIROS has 6 thrusters for submarine voyage and 4 legs for walking on the top of the strainer. An inverse kinematic algorithm was implemented in the robot controller for exact walking on the top of the IRWST strainer. The IRWST strainer has several top cross braces that are extruded on the top of the strainer, which can be obstacles of walking on the strainer, to maintain the frame of the strainer. Therefore, a robot leg should arrive at the position beside the top cross brace. For this reason, we used an image processing technique to find the top cross brace in the sole camera image. The sole camera image is processed to find the existence of the top cross brace using the cross edge detection algorithm in real time. A 5-DOF robot arm that has multiple camera modules for simultaneous inspection of both sides can penetrate narrow gaps. For intuitive presentation of inspection results and for management of inspection data, inspection images are stored in the control PC with camera angles and positions to synthesize and merge the images. The synthesized images are then mapped in a 3D CAD model of the IRWST strainer with the location information. An IRWST strainer mock-up was fabricated to teach the robot arm scanning and gaiting. It is important to arrive at the designated position for inserting the robot arm into all of the gaps. Exact position control without anchor under the water is not easy. Therefore, we designed the multi leg robot for the role of anchoring and positioning. Quadruped robot design of installing sole cameras was a new approach for the exact and stable position control on the IRWST strainer, unlike a traditional robot for underwater facility inspection. The developed robot will be practically used to enhance the efficiency and reliability of the inspection of nuclear power plant components.

• Journal of Microbiology and Biotechnology
• /
• v.30 no.3
• /
• pp.459-468
• /
• 2020

This study established a new polymerase spiral reaction (PSR) that combines with reverse transcription reactions for HCV detection targeting 5'UTR gene. To avoid cross-contamination of aerosols, an isothermal amplification tube (IAT), as a separate containment control, was used to judge the result. After optimizing the RT-PSR reaction system, its effectiveness and specificity were tested against 15 different virus strains which included 8 that were HCV positive and 7 as non-HCV controls. The results showed that the RT-PSR assay effectively detected all 8 HCV strains, and no false positives were found among the 7 non-HCV strains. The detection limit of our RT-PSR assay is comparable to the real-time RT-PCR, but is more sensitive than the RT-LAMP. The established RT-PSR assay was further evaluated for detection of HCV in clinical blood samples, and the resulting 80.25% detection rate demonstrated better or similar effectiveness compared to the RT-LAMP (79.63%) and real-time RT-PCR (80.25%). Overall, the results showed that the RT-PSR assay offers high specificity and sensitivity for HCV detection with great potential for screening HCV in clinical blood samples.

• Journal of Preventive Medicine and Public Health
• /
• v.22 no.4 s.28
• /
• pp.542-554
• /
• 1989

The skyrocketing inflation of medical costs has become a major health problem among most developed countries. Korea, which recently covered the entire population with National Health Insurance, is facing the same problem. The proportion of health expenditure to GNP has increased from 3% to 4.8% during the last decade. This was remarkable, if we consider the rapid economic growth during that time. A few policy analysts began to raise cost containment as an agenda, after recognizing the importance of medical cost inflation. In order to Prepare an appropriate alternative for the agenda, it is necessary to find out reasons for the cost inflation. Then, we should focus on the reasons which are controllable, and those whose control are socially desirable. This study is designed to articulate the theory of medical cost inflation through literature reviews, to find out reasons for cost inflation, by analyzing aggregated data with a deterministic model. Finally to identify determinants of changes in both medical demand and service intensity which are major reasons for cost inflation. The reasons for cost inflation are classified into cost push inflation and demand pull inflation, The former consists of increases in price and intensity of services, while the latter is made of consumer derived demand and supplier induced demand. We used a time series (1983-1987), and cross sectional (over regions) data of health insurance. The deterministic model reveals, that an increase in service intensity is a major cause of inflation in the case of inpatient care, while, more utilization, is a primary attribute in the case of physician visits. Multiple regression analysis shows that an increase in hospital beds is a leading explanatory variable for the increase in hospital care. It also reveals, that an introduction of a deductible clause, an increase in hospital beds and degree of urbanization, are statistically significant variables explaining physician visits. The results are consistent with the existing theory, The magnitude of service intensity is influenced by the level of co-payment, the proportion of old age and an increase in co-payment. In short, an increase in co-payment reduced the utilization, but it induced more intensities or services. We can conclude that the strict fee regulation or increase in the level of co-payment can not be an effective measure for cost containment under the fee for service system. Because the provider can react against the regulation by inducing more services.