• Journal of Educational Research in Mathematics
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• v.24 no.3
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• pp.387-407
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• 2014

This study investigeted secondary math teachers' difficulties of technology in geometry class with grounded theory by Strauss and Corbin. 178 secondary math teachers attending the professional development program on technology-based geometry teaching at eight locations in January 2014, participated in this study with informed consents. Data was collected with an open-ended questionnaire survey. In line with grounded theory, open, axial and selective coding were applied to data analysis. According to the results of this study, teachers were found to experience resistance in using technology due to new learning and changes, with knowledge and awareness of technology effectively interacting to lessen such resistance. In using technology, teachers were found to go through the 'access-resistance-unaccepted use-acceptance' stages. Teachers having difficulties in using technology included the following four types: 'inaccessible, denial of acceptance, discontinuation of use, and acceptance 'These findings suggest novel perspectives towards teachers having difficulties in using technology, providing implications for teachers' professional development.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.2
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• pp.144-152
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• 2011

This paper presents a new scheme for fault detection and isolation in the satellite system. The purpose of this paper is to develop a fault detection, isolation and diagnosis algorithm based on the bank of interacting multiple model (IMM) filter for both total and partial faults in a satellite attitude control system (ACS). In this paper, IMM are utilized for detection and diagnosis of anticipated actuator faults in a satellite ACS. Other fault detection, isolation (FDI) schemes using conventional IMM are compared with the proposed FDI scheme. The FDI procedure is developed in two stages. In the first stage, 11 EKFs actuator fault models are designed to detect wherever actuator faults occur. In the second stage of the FDI scheme, two filters are designed to identify the fault type which is either the total or partial fault. An important feature of the proposed FDI scheme can decrease fault isolation time and figure out not only fault detection and isolation but also fault type identification.

• Experimental and Molecular Medicine
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• v.50 no.11
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• pp.10.1-10.11
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• 2018

Although early studies suggested that bladder cancer (BCa) is more prevalent in men than in women, muscle-invasive rates are higher in women than in men, suggesting that sex hormones might play important roles in different stages of BCa progression. In this work, we found that estrogen receptor beta ($ER{\beta}$) could increase BCa cell proliferation and invasion via alteration of miR-92a-mediated DAB2IP (DOC-2/DAB2 interacting protein) signals and that blocking miR-92a expression with an inhibitor could partially reverse $ER{\beta}$-enhanced BCa cell growth and invasion. Further mechanism dissection found that $ER{\beta}$ could increase miR-92a expression at the transcriptional level via binding to the estrogen-response-element (ERE) on the 5' promoter region of its host gene C13orf25. The $ER{\beta}$ up-regulated miR-92a could decrease DAB2IP tumor suppressor expression via binding to the miR-92a binding site located on the DAB2IP 3' UTR. Preclinical studies using an in vivo mouse model also confirmed that targeting this newly identified $ER{\beta}$/miR-92a/DAB2IP signal pathway with small molecules could suppress BCa progression. Together, these results might aid in the development of new therapies via targeting of this $ER{\beta}$-mediated signal pathway to better suppress BCa progression.

• Advances in aircraft and spacecraft science
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• v.3 no.3
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• pp.243-257
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• 2016

The increase of air traffic volume has brought an increasing amount of issues related to carbon and NOx emissions and noise pollution. Aircraft manufacturers are concentrating their efforts to develop technologies to increase aircraft efficiency and consequently to reduce pollutant discharge and noise emission. Ultra High By-Pass Ratio engine concepts provide reduction of fuel consumption and noise emission thanks to a decrease of the jet velocity exhausting from the engine nozzles. In order to keep same thrust, mass flow and therefore section of fan/nacelle diameter should be increased to compensate velocity reduction. Such feature will lead to close-coupled architectures for engine installation under the wing. A strong jet-wing interaction resulting in a change of turbulent mixing in the aeroacoustic field as well as noise enhancement due to reflection phenomena are therefore expected. On the other hand, pressure fluctuations on the wing as well as on the fuselage represent the forcing loads, which stress panels causing vibrations. Some of these vibrations are re-emitted in the aeroacoustic field as vibration noise, some of them are transmitted in the cockpit as interior noise. In the present work, the interaction between a jet and wing or fuselage is reproduced by a flat surface tangential to an incompressible jet at different radial distances from the nozzle axis. The change in the aerodynamic field due to the presence of the rigid plate was studied by hot wire anemometric measurements, which provided a characterization of mean and fluctuating velocity fields in the jet plume. Pressure fluctuations acting on the flat plate were studied by cavity-mounted microphones which provided point-wise measurements in stream-wise and spanwise directions. Statistical description of velocity and wall pressure fields are determined in terms of Fourier-domain quantities. Scaling laws for pressure auto-spectra and coherence functions are also presented.

• Journal of Family Resource Management and Policy Review
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• v.25 no.4
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• pp.15-30
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• 2021

This study aims to apprehend resources that affect level of happiness according to the types of work and leisure in single-person households, and suggests measures to effectively manage. Single-person households not only have different demographic characteristics such as gender and age, but also they have different resources, so there is a need to look at them simple as an individual subject, but as a complicated system from more integrated view. Thus, this study saw the single-person household as an organism existing in a complicated environment based on examining the previous researches. This work deigned the research model by applying the human ecological point of view consistently interacting with the environment. This study suggested an hypothesis under the assumption that the resources such as leisure, infrastructure, social activity and work-life balance support system will influence the level of happiness of single-person household

• Explosives and Blasting
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• v.37 no.2
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• pp.14-21
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• 2019

Distinct element method is a powerful numerical tool for modelling the jointed rock masses. It is also a useful tool for modelling of later stage of blasting requiring large displacement. The distinct element method utilizes a rigid block idea in which the interacting force between distinct elements is calculated from contact displacement as elements penetrate slightly. The properties of joints defined as the boundaries of distinct elements are critical parameters to determine the block behavior, and affect the deformation and failure mode. However, regardless of real joint properties, joint stiffnesses have sometimes been selected without special concern just to prevent elements from penetrating too far into each other in some quasi-static problems. Depending on whether the main interest in the analysis is the prediction of the deformation with high precision, or the prediction of the block behaviour after failure, the input data such as joint stiffness may or may not have a significant effect on the results. The purpose of this study is to provide a sound understanding of the effect of the joint stiffness on the distinct element analysis results, and to help guide the selection of input data.

• Nuclear Engineering and Technology
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• v.51 no.6
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• pp.1540-1553
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• 2019

A nuclear power plant (NPP) is a highly complex system-of-systems as manifested through its internal systems interdependence. The negative impact of such interdependence was demonstrated through the 2011 Fukushima Daiichi nuclear disaster. As such, there is a critical need for new strategies to overcome the limitations of current risk assessment techniques (e.g. the use of static event and fault tree schemes), particularly through simulation of the nonlinear dynamic feedback mechanisms between the different NPP systems/components. As the first and key step towards developing an integrated NPP dynamic probabilistic risk assessment platform that can account for such feedback mechanisms, the current study adopts a system dynamics simulation approach to model the thermal dynamic processes in: the reactor core; the secondary coolant system; and the pressurized water reactor. The reactor core and secondary coolant system parameters used to develop system dynamics models are based on those of the Palo Verde Nuclear Generating Station. These three system dynamics models are subsequently validated, using results from published work, under different system perturbations including the change in reactivity, the steam valve coefficient, the primary coolant flow, and others. Moving forward, the developed system dynamics models can be integrated with other interacting processes within a NPP to form the basis of a dynamic system-level (systemic) risk assessment tool.

• Journal of the Korea Convergence Society
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• v.12 no.6
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• pp.1-8
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• 2021

The purpose of this study is to study the interaction structure of a smart farm for controlled environment horticulture. As a research method, interaction factors were analyzed by defining the growth stages of humans, plants, and plants, which are the subjects of interaction during the production, distribution, sales and consumption stages of smart farms. Additionally, on-site survey was used to differentiate between one-time, short-term, and long-term, depending on the behavior and operation of the interacting entity and time. As a result, the research came up to a finding that 1) Human and Plant are based on interactions of 'one-time, short-term' 2) Plant and Smart Farm as 'short-term' 3) Smart Farm and Human as 'short-term and long-term'. For this reason, this study is meaningful in deriving the relationship between the subjects and the interaction elements in the production stage of the smart farm and presenting a new interaction structure model by structuring them.

• Knowledge Management Research
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• v.23 no.2
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• pp.169-192
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• 2022

With the spread of Internet personal broadcasting service, the number of personal broadcasting hosts (BJs: Broadcasting Jockeys) and viewers is increasing, and immediate communication between them is also actively taking place. This study examines whether the mechanism to suppress deviant behavior of BJ works effectively and how viewers interacting with BJs affect the intentions of deviant behaviors of BJs. Through the structural equation model, the effect of formal and informal sanctions of deterrence theory on BJs' intention of deviant broadcasting through their policy compliance attitude was investigated. The moderating effect of social pressure on the relationship between BJs' policy compliance attitude and their deviant broadcasting intention was confirmed. A total of 234 data were analyzed by surveying Africa TV BJs. As a result of the analysis, it was found that informal as well as formal sanctions increased the BJs' attitude toward policy compliance. However, it was confirmed that the social pressure perceived by BJs from Internet personal broadcasting viewers reduced the effect of policy compliance attitudes on reducing deviant broadcasting intentions.

• Journal of Veterinary Science
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• v.24 no.1
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• pp.2.1-2.14
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• 2023

Background: Hypothermia is a crucial environmental factor that elevates the risk of cardiovascular disease, but the underlying effect is unclear. Objectives: This study examined the role of cold stress (CS) in cardiac injury and its underlying mechanisms. Methods: In this study, a chronic CS-induced myocardial injury model was used; mice were subjected to chronic CS (4℃) for three hours per day for three weeks. Results: CS could result in myocardial injury by inducing the levels of heat shock proteins 70 (HSP70), enhancing the generation of creatine phosphokinase-isoenzyme (CKMB) and malondialdehyde (MDA), increasing the contents of tumor necrosis factor-α (TNF-α), high mobility group box 1 (HMGB1) interleukin1b (IL-1β), IL-18, IL-6, and triggering the depletion of superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH). Multiple signaling pathways were activated by cold exposure, including pyroptosis-associated NOD-like receptor 3 (NLRP3)-regulated caspase-1-dependent/Gasdermin D (GSDMD), inflammation-related toll-like receptor 4 (TLR4)/myeloid differentiation factor 88 (MyD88)-mediated nuclear factor kappa B (NF-κB), and mitogen-activated protein kinase (MAPK), as well as oxidative stressinvolved thioredoxin-1/thioredoxin-interacting protein (Txnip) signaling pathways, which play a pivotal role in myocardial injury resulting from hypothermia. Conclusions: These findings provide new insights into the increased risk of cardiovascular disease at extremely low temperatures.