• Journal of Satellite, Information and Communications
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• v.12 no.3
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• pp.35-40
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• 2017

Out-of-limit (OOL) alarm method that is threshold checking of telemetry value is widely used for the satellites fault diagnosis and health monitoring. However, it requires engineering knowledge and effort to define delicate threshold value and has limitations that anomalous behaviors within the defined limits can't be detected. In this paper, we propose a satellite anomalous behavior detection system through fuzzy model that is composed by important statistical feature selected by rough-set theory. Not pre-defined anomaly is detected because only normal state data is used for fuzzy model. Also, anomalous behavior within the threshold limit is detected by using statistic feature that can be collected without engineering knowledge. The proposed system successfully detected non-ordinary state for battery temperature telemetry.

• Journal of Educational Research in Mathematics
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• v.20 no.3
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• pp.255-274
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• 2010

The main goal of this study is to provide a practical help to teachers who want to practice Problem-Based Learning in mathematics for establishing and realizing PBL environment. This study also produces mathematics PBL Learning Model and Criteria to Judge to help practice and to vitalize PBL in mathematics. To solve the research topics, I reviewed theoretical issues related to PBL, which became theoretical bases of this study. And then, from the theoretical background, items of criteria to judge mathematical problems in mathematics PBL are abstracted. And, through checking on content validity by experts, criteria to judge mathematical problems in mathematics PBL are completed. Also, based on previous PBL models, learning model in mathematics PBL that takes characteristics of mathematics into account is suggested through case studies by observing, a qualitative research method, on PBL study to materialize it. This research is expected to help teachers who want to practice PBL in mathematics.

• Structural Engineering and Mechanics
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• v.58 no.2
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• pp.277-300
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• 2016

Cold-formed steel (CFS) sections are becoming an increasingly popular solution for constructing floors in residential, healthcare and education buildings. Their reduced weight, however, makes them prone to excessive vibrations, increasing the need for accurate prediction of CFS floor modal properties. By combining experimental modal analysis of a full-scale CFS framed building and its floors and their numerical finite element (FE) modelling this paper demonstrates that the existing methods (based on the best engineering judgement) for predicting CFS floor modal properties are unreliable. They can yield over 40% difference between the predicted and measured natural frequencies for important modes of vibration. This is because the methods were adopted from other floor types (e.g., timber or standard steel-concrete composite floors) and do not take into account specific features of CFS floors. Using the adjusted and then updated FE model, featuring semi-rigid connections led to markedly improved results. The first four measured and calculated CFS floor natural frequencies matched exactly and all relevant modal assurance criterion (MAC) values were above 90%. The introduction of flexible supports and more realistic modelling of the floor boundary conditions, as well as non-structural $fa{\c{c}}ade$ walls, proved to be crucial in the development of the new more successful modelling strategy. The process used to develop 10 identified and experimentally verified FE modelling parameters is based on published information and parameter adjustment resulting from FE model updating. This can be utilised for future design of similar lightweight steel floors in prefabricated buildings when checking their vibration serviceability, likely to be their governing design criterion.

• Journal of Hydrogen and New Energy
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• v.28 no.3
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• pp.252-272
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• 2017

Fuel cell systems have to satisfy acceptable operating reliability, sufficient lifetime and price to enter the market in competition with existing products. Fuel cells are made up of complex element technologies and various problems related to the failure of the components can affect the reliability and safety of the system. This problem can be overcome by introducing a monitoring and supervisory control system in addition to automatic control to detect the failure of the fuel cell quickly and properly diagnose the performance degradation. For the fault detection and diagnosis of polymer electrolyte fuel cells, the model based method using the theoretical superposition value and the non-model based method of checking the signal tendency or the converted signal characteristic can be applied. The methods analyzed in this paper can contribute to the development of integrated monitoring and control technology for the whole system as well as the stack.

• Journal of Biosystems Engineering
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• v.39 no.3
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• pp.151-157
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• 2014

Purpose: In order to develop strategies to prevent farm-work accidents relating to agricultural machinery, influential factors were examined in this paper. The effects of these factors were quantified using logistic regression. Methods: Based on the results of a survey on farm-work accidents conducted by the National Academy of Agricultural Science, 21 tentative independent variables were selected. To apply these variables to regression, the presence of multicollinearity was examined by comparing correlation coefficients, checking the statistical significance of the coefficients in a simple linear regression model, and calculating the variance inflation factor. A logistic regression model and determination method of its goodness of fit was defined. Results: Among 21 independent variables, 13 variables were not collinear each other. The results of a logistic regression analysis using these variables showed that the model was significant and acceptable, with deviance of 714.053. Parameter estimation results showed that four variables (age, power tiller ownership, cognizance of the government's safety policy, and consciousness of safety) were significant. The logistic regression model predicted that the former two increased accident odds by 1.027 and 8.506 times, respectively, while the latter two decreased the odds by 0.243 and 0.545 times, respectively. Conclusions: Prevention strategies against factors causing an accident, such as the age of farmers and the use of a power tiller, are necessary. In addition, more efficient trainings to elevate the farmer's consciousness about safety must be provided.

• The Journal of Korean Physical Therapy
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• v.21 no.2
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• pp.65-70
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• 2009

Purpose: The pathophysiology of congenital muscular torticollis (CMT) is that the sternoclavicularmastoid (SCM) is shortened on the involved side by fibrosis, leading to an ipsilateral tilt and contralateral rotation of the face and chin. The aim of this study was to examine the effect of physical therapy and develop a mass diameter prediction model for infants with CMT. Methods: Fifty six patients were diagnosed with CMT between April 2003 and December 2008. Infants with neurological complications, and spasmodic and ocular torticollis were excluded. Physical therapy was applied to those masses in the SCM muscles of those infants after checking their physical findings and the diameter of the mass with ultrasonography. Their physical findings and mass diameter was reevaluated when their neck tilt was under $5^{\circ}$. Results: The mean age when physical therapy was started was 35 days. After a mean 90 days of treatment, the subjects showed improvement in the neck tilt. Subjects whose neck tilted above $15^{\circ}$ showed significant improvement in neck tilt decreased their mass diameter (p<0.01). Facial symmetric infants showed a shorter recovery duration than the facial asymmetric infants (p<0.05). A mass decreasing model based on the diameter of the mass, facial symmetry or not and the physical therapy start day after birth was developed by linear regression. Conclusion: Physical therapy is an effective treatment for CMT. The change in the diameter of the mass on the SCM muscles after treatment can be predicted.

• Journal of Korean Society for Quality Management
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• v.41 no.1
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• pp.109-118
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• 2013

Purpose: Given the several proper models for given mixture components-process variables experimental data, we propose a strategy to find the optimal condition in which the performance of the responses is well-behaved under those models. Methods: Given the mixture experimental data with process variables, first we choose the reasonable starting models among the class of admissible product models based on the model selection criteria and then, search for the candidate models that are the subset models of the starting model by the sequential variable selection method or all possible regressions procedure. Good candidate models are screened by the evaluation of model selection criteria and checking the residual plots for the validity of the model assumption. Results: We propose a strategy to find the optimal condition in which the performance of the responses is well-behaved under those good candidate models by adopting the optimization methods developed in multiple responses surface methodology. Conclusion: A strategy is proposed to find the optimal condition in which the performance of the responses is well-behaved under those proper combined models. This strategy to find the optimal condition is illustrated with the example in this paper.

• Journal of Korean Society for Geospatial Information Science
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• v.17 no.3
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• pp.49-56
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• 2009

Recently, a generation of high quality mosaic images from video sequences has been attempted by a variety of investigations. Among the matter of investigation, in this paper, generation on stereo mosaic utilizing airborne-video sequence images is focused upon. The stereo mosaic is made by creating left and right mosaic which are fabricated by front and rear slices having different viewing angle in consecutive video frames. For making the stereo mosaic, motion parameters which are able to define geometric relationship between consecutive video frames are determined. For determining motion parameters, affine model which is able to explain relative motion parameters is applied by this paper. The mosaicing method using relative motion parameters is called by free mosaic. The free mosaic proposed in this paper consists of 4 step processes: image registration with reference to first frame using affine model, front and rear slicing, stitching line definition and image mosaicing. As the result of experiment, the left and right mosaic image, anaglyphic image for stereo mosaic images are showed and analyzed y-parallax for checking accuracy.

• Convergence Security Journal
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• v.20 no.3
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• pp.39-46
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• 2020

In order to protect the business information of the enterprise, the company is engaged in various information security activities, such as establishing an information security management system, establishing and operating an information security system, checking vulnerabilities and security controls. It is an enterprise information security governance that organizes various information security activities for enterprise business, and it needs to be systematized to operate them effectively. In this study, to systematize the enterprise information security governance, we would like to explore the existing Enterprise Information Portal(EIP) model and propose an Enterprise Information Security Portal(EISP) model based on it. The Enterprise Information Security Portal(EISP) model provides an integrated environment for supporting the activities of the information security departments by systemizing the enterprise information security governance, which is a variety of information security activities of the enterprises, so that the information security activities of the enterprises can participate directly from CEO to executives and employees, not just from the information security departments.

• Journal of the Korean Geotechnical Society
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• v.20 no.9
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• pp.91-103
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• 2004

A series of shaking table model tests were performed to verify the validity of similitude law, which is suggested by lai (1989) to simulate the dynamic behavior of soil-fluid-structure system for is shaking table tests. In the tests, the similitude law suggested by lai was applied to determine the length and the time scaling factors. Also, the steady state concept was used in determining the density of model backfill soil, which is a key factor in simulating the development of excess pore pressure during shaking. The similitude law was verified by checking whether three different sizes of quay walls show the identical behavior or not. The similar responses of acceleration, excess pore pressure and horizontal displacement of walls were obtained far the small and large models. However, the medium model showed larger responses than those of the small and large models because of the resonance between the frequency of input acceleration and the natural frequency of the wall system. In addition, the vertical displacement and rotational angle of the walls became larger with the increase of model size.