• The Mathematical Education
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• v.61 no.4
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• pp.597-612
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• 2022

Recently, large-scale mathematics assessments are shifting from traditional paper-based tests to computer-based tests, nationally and internationally. This study explored the mode effect (the difference in student achievement by the change of test mode) according to the types of test items, the technological function reflected in the items, the characteristics of students' computer use, and the computer-based test environment. To this end, we analyzed the results of the 2020 national assessment of educational achievement of high school mathematics conducted on a paper and computer basis. As a result, firstly, the mode effect induced by the mode transition was generally insignificant, but the mode effect was larger in the extended response type than other types. Secondly, there were differences in the mode effect according to the transition to test with computer mode where innovative items were added. Thirdly, the difference between mode effects was statistically significant according to the student's sense of efficacy in computer use. The results of this study suggest that innovative items should be introduced deliberately according to the targeted content and competency in evaluation, and that assessment design and environment preparation need to be carefully developed so that nonessential abilities other than students' mathematical ability or incidental situation do not distort the assessment results.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.1203-1204
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• 2011

• Journal of Periodontal and Implant Science
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• v.39 no.2
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• pp.139-148
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• 2009

Purpose: Ultrasonic scalers have been widely used for removing biofilm which is considered as major etiologic factor of periodontal disease. The purpose of this study was to evaluate the effect of working parameters of piezoeletric ultrasonic scaler with scaler tip (No. 1 tip) on casting gold alloy removal. Methods: Type III dental casting gold alloy (Firmilay$^{circledR}$, Jelenko Inc, CA, USA) was used as substitute for tooth substance. Piezoeletric ultrasonic scaler and No.1 scaler tip (P-Max$^{circledR}$, Satelec, France) were selected. The selected working parameters were mode (P mode, S mode), power setting (2, 4, 8) and lateral force (0.5 N, 1.0 N, 2.0 N). The effect of working parameters was evaluated in terms of ablation depth, ablation width and ablation area. Results: Mode influenced ablation depth and ablation area. Power also influenced ablation depth and ablation area. Especially, Power 2 and power 8 showed statistically significant difference. Lateral force had influence on ablation width, and 0.5 N resulted significant increase compared with 1.0 N and 2.0 N. Ablation depth was influenced by mode, power and lateral force and defect width was influenced by lateral force. Ablation area was influenced by mode and power. Conclusions: It can be concluded that the use of piezoelectric ultrasonic scaler with No. 1 scaler tip in S mode and high power may result in significant loss of tooth substance.

• Membrane Journal
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• v.21 no.3
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• pp.263-269
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• 2011

In the operation of submerged membrane-coupled sequencing batch reactor, the effect of filling step on the removal efficiency and filtration performance were investigated. Two sets of operation modes, the filling step located in the beginning of aerobic step (Mode-1) and the beginning of anoxic step (Mode-2), during 89 days were conducted. There was no wide difference in the COD removal and filtration performance between two sets of operation modes. But in the removal efficiency of nutrients (total nitrogen and total phosphorous), Mode-2 was more effective than Mode-1. In the case of Mode-2, average removal efficiencies of COD, total nitrogen, and total phosphorous were 99.1, 73.3, and 77.3%, respectively.

• Journal of Korean Neurosurgical Society
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• v.51 no.1
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• pp.24-30
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• 2012

Objective : This study was conducted to assess the clinical significance of traumatic brain stem injury (TBSI) reflected on Glasgow Coma Score (GCS) and Glasgow Outcome Score (GOS) by various clinical variables. Methods : A total of 136 TBSI patients were selected out of 2695 head-injured patients. All initial computerized tomography and/or magnetic resonance imaging studies were retrospectively analyzed according to demographic- and injury variables which result in GCS and GOS. Results : In univariate analysis, mode of injury showed a significant effect on combined injury (p<0.001), as were the cases with skull fracture on radiologic finding (p<0.000). The GCS showed a various correlation with radiologic finding (p<0.000), mode of injury (p<0.002), but less favorably with impact site (p<0.052), age (p<0.054) and skull fracture (p<0.057), in order of statistical significances. However, only GOS showed a definite correlation to radiologic finding (p<0.000). In multivariate analysis, the individual variables to enhance an unfavorable effect on GCS were radiologic finding [odds ratio (OR) 7.327, 95% confidence interval (CI)], mode of injury (OR; 4.499, 95% CI) and age (OR; 3.141, 95% CI). Those which influence an unfavorable effect on GOS were radiologic finding (OR; 25.420, 95% CI) and age (OR; 2.674, 95% CI). Conclusion : In evaluation of TBSI on outcome, the variables such as radiological finding, mode of injury, and age were revealed as three important ones to have an unfavorable effect on early stage outcome expressed as GCS. However, mode of injury was shown not to have an unfavorable effect on late stage outcome as GOS. Among all unfavorable variables, radiological finding was confirmed as the only powerful prognostic variable both on GCS and GOS.

• Transactions of the Society of Information Storage Systems
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• v.3 no.1
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• pp.1-4
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• 2007

A high density optical data storage device has been required for many years. In the field of the optical data storage, a near-field recording (NFR) technology is considered as a next generation one for achieving the high data density. Due to an evanescent wave effect occurred under 100nm distance which is the excessively small distance between the SIL and the disc, the most significant and difficult problem in this technology is to maintain a gap between a solid immersion lens (SIL) and a disc. Also, maintaining the gap under at least 50nm is required in the NFR gap servo system to use the evanescent wave effect efficiently. There are some institutes that have shown the novel gap servo control. In general, they use a mode switching servo method which consists of approach, hand-over and gap control mode. However there is a critical problem such as an overshoot at the tuning point from the approach mode to the hand-over mode, which may cause a collision between the SIL and the disc. In this paper, we show our NFR system and an improved gap servo system using an exponential function as the approach mode which can reduce the overshoot.

• Computers and Concrete
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• v.28 no.5
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• pp.507-519
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• 2021

In this study, a new procedure was proposed in order to predict the crack pattern and failure mode of steel fiber reinforced concrete (SFRC) corbels. Moreover, an experimental study was carried out in order to investigate the effect of several parameters, such as compressive strength, tensile strength, steel fiber ratio, shear span on the mechanical behavior of SFRC corbels in detail. Totally, 24 RC and SFRC corbels were prepared for the experimental study. Experimental results indicate that each investigated parameter has noticeable effect on the load capacity and failure mode of SFRC corbels. Moreover, finite element (FE) model of the tested corbels were prepared and efficiency of FE model was investigated for further studies. Comparison of FE and experimental results show that there is an acceptable fit between them regarding load capacity and crack patterns. Thereafter, parametric study was carried out via FE analyses in order to obtain a methodology for crack pattern and failure mode prediction of SFRC corbels. As a result of parametric studies, a new procedure was proposed as flowcharts in order to predict the failure mode of SFRC corbels for normal and high strength concrete class separately.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.359-364
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• 2004

In this study, experiments were tried on the mixed-mode I+II single overloading model which changes the loading mode of overload and fatigue load. Aspects of deformation field in front of the crack which is formed by mixed-mode I+II single overloading were experimentally studied. Then the shape and size of mixed-mode plastic zone were approximately calculated. The propagation behavior of fatigue crack was examined under the test conditions combined by changing the loading mode. The behavior of fatigue cracks were greatly affected by shapes of plastic deformation field and applying mode of fatigue load. Accuracy of prediction and evaluation for fatigue life may be improved by considering all aspects of deformation and behavior of fatigue cracks.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.5 s.236
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• pp.716-725
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• 2005

The method of substructure synthesis o. component mode synthesis(CMS) provides an effective means of dynamic analysis of very large and/or complex structures. In this study, residual dynamic flexibility attachment modes in hybrid component mode synthesis are considered for the purpose of exactly compensating the effect of higher order truncated modes. Following this way, the analysis accuracy of the synthesized structure can be improved effectively with less computational effort. In order to show the accuracy and effectiveness of the proposed hybrid component mode synthesis(HCMS), numerical experiments were carried out for the models of a clamped-clamped beam. The results verified the effectiveness of the proposed method.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.626-631
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• 2007

MR(Magneto-rheological) fluid is smart material that can be changed viscosity by controlling the magnetic field. MR damper with MR fluid can control damping force. It can be used extensively many engineering structures for reducing the effect of dynamic external disturbances. There are three kinds of MR dampers, such as valve mode, direct-shear mode and squeeze mode. In this study, design process of direct-shear mode MR damper with the MR fluid gap was developed. The parameters that used in the direct-shear mode MR damper Informed from the experiment of valve mode MR damper of Lord company. Magnetic analysis with finite element method was performed to find the optimal annular gap.