• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권9호
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• pp.2314-2333
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• 2023

It is significant to predict the performance degradation of complex electromechanical systems. Among the existing performance degradation prediction models, belief rule base (BRB) is a model that deal with quantitative data and qualitative information with uncertainty. However, when analyzing dynamic systems where observable indicators change frequently over time and working conditions, the traditional belief rule base (BRB) can not adapt to frequent changes in working conditions, such as the prediction of aeroengine performance degradation considering working condition. For the sake of settling this problem, this paper puts forward a new hidden belief rule base (HBRB) prediction method, in which the performance of aeroengines is regarded as hidden behavior, and operating conditions are used as observable indicators of the HBRB model to describe the hidden behavior to solve the problem of performance degradation prediction under different times and operating conditions. The performance degradation prediction case study of turbofan aeroengine simulation experiments proves the advantages of HBRB model, and the results testify the effectiveness and practicability of this method. Furthermore, it is compared with other advanced forecasting methods. The results testify this model can generate better predictions in aspects of accuracy and interpretability.

• 한국학교보건학회지
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• 제3권2호
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• pp.63-87
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• 1990

The purpose of this study was to investigate the performance rate of regular health instruction by school nurses and its related factors. These data were collected by questionnaire in Mar. 1990. Total 986 school nurses who have been working primary, secondary schools in Seoul were given the questionnaire, and 672 school nurses' respectively, were finally analyzed. Analysis of the data was done utilizing SPSS/PC+for percentage, frequency, mean, $X^2$-test, t-test, ANOVA, correlation, regression. The major findings of this study were as follows : 1. Thc performance rate of regular health instruction by school nurses was 77.7% of 552 respondents. 2. The school nurses in primary school(87.0%) were more likely to perform regular health instruction than the school nurses in secondary school (63.8%). 3. The teachers of regular health instruction were more likely to display favorable attitudes toward need of health instruction. The school level was not statistically significant(P>0.05). 4. The evidence from the data analysis supported the proposition that the teachers of regular health instruction had more positive attitude toward the establishment of health subject(80.3%). The school level was statistically significant(P<0.05). 5. The school principal was a highly significant factor as it affected the performance rate of regular health instruction by school nurses. The school level was statistically significant(P<0.001). 6. The length of past career, the degree of self confidence on health instruction, the need of health instruction did affect the performance rate of regular health instruction by school nurses. On the basis of the above mentioned, so as for regular health instruction of school to be activated more throughly, regular class must be introduced in the form of establishment of health subject, enhancement of quality on the part of school nurses, made and various methods for enhancing perception toward the regular health instruction on the part of school principal are to be carried out.

• 대한수학교육학회지:수학교육학연구
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• 제9권1호
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• pp.333-350
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• 1999

The purpose of this study is to define performance assessment of mathematics, to make a model of performance task of mathematics for the first grade middle school students in higher group, to examine validity and reliability of performance task and to investigate the effects on the students' achievement and attitude. It first defines performance assessment and exanmines its main features and scoring methods. Based on these, nine performance assessment tasks and scoring criteria were designed for the first grade middle school students in higher group. The validity of performance tasks were examined by experts. The loaming achievement and mathematical attitude test between two groups were performed as pre and post test. The thinking of students about performance assessment was investigated by attitude survey. The results of this study are as follows: First, the validity of the performance tasks is very high. Second, The control group. Forth, there is a difference in student's attitude about mathematics between scorer reliability was high due to the scorer training. Third, there is little difference in teaming achievement between experimental and experimental and control group in 5% meaningful levels. That is, student's of both groups attitude about mathematics comes negatives, but the width of change of negative attitude in experimental group is less than control group. In the trend of negative attitude of mathematics as grade comes higher, this results showed that performance assessment of mathematics had positive influence on attitude of mathematics. The result of survey about mathematical performance assessment experience showed that students have positive attitude to performance assessment and recognized effectiveness of the performance assessment of mathematics.

• Journal of electromagnetic engineering and science
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• 제1권2호
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• pp.146-155
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• 2001

This paper describes the improvement in performance of power amplifiers by Defected Ground Structure (DGS) for several operating classes. Due to its excellent capability of harmonic rejection, DGS plays a threat role in improving the main performance of power amplifiers such as output power, power added efficiency, harmonic rejection, and intermodulation distortion (IMD3). In order to verify the improvement in performance of power amplifiers by DGS, measured data for a 30 Watts power amplifier with and without DGS attached under several operating classes are illustrated and compared. The principle of the performance improvement is described with simple Volterra nonlinear transfer functions. Also, the measured performance far two cases, i.e. with and without DGS, and the quantities of improvement fur the various operating classes are compared and discussed.

• 공학교육연구
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• 제17권1호
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• pp.3-11
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• 2014

The purpose of this study was to verity the effect of project method on the task performance ability in development of a solar-tracking-control-system of specialized high school. In order to carry out this study, 2 classes of technical high school in Jeonbuk are chosen as experimental and control groups. The experimental group was taught by project method and the control group was taught by traditional instruction. Project method was designed by 4 stages-selection of goal, planning, implementation and evaluation. According to these stages, experimental group's students carried out the project that developing solar tracking control system in solar generation. The results of this study are as follows; the project method was more effective than the traditional instruction in planning ability for task performance and implementation ability, subordinates of task performance ability. However, information gathering ability and evaluation ability on task performance, others in subordinates, it is not clear that the project method is more effective.

• 한국지진공학회논문집
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• 제23권1호
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• pp.71-82
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• 2019

Most school buildings consist of reinforced concrete (RC) moment frames with masonry infills. The longitudinal direction frames of those school buildings are relatively weak due to the short-column effects caused by the partial masonry infills and need to be evaluated carefully. In 'Manual for Seismic Performance Evaluation and Retrofit of School Facilities' published in 2018, response modification factor of 2.5 is applied to non-seismic RC moment frames with partial masonry infills, but sufficient verification of the factor has not been reported yet. Therefore, this study conducted seismic performance evaluation of planar RC moment frames with partial masonry infills in accordance with both linear analysis and nonlinear static analysis procedures presented in the manual. The evaluation results from the different procedures are compared in terms of assessed performance levels and number of members not meeting target performance objectives. Finally, appropriate response modification factors are proposed with respect to a shear-controlled column ratio.

• The Journal of Asian Finance, Economics and Business
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• 제9권7호
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• pp.101-108
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• 2022

The outbreak of Coronavirus disease 2019 (COVID-19) has caused serious impacts not only on human health but also on the economies around the world. Enterprises play an important role in the development of every country but it is also one of the most affected sectors during the pandemic. Drawing on panel data of 131 enterprises listed on the Vietnamese stock exchange from 2016Q1 to 2021Q3, this study aims to investigate the impact of the COVID-19 pandemic on firm performance. Enterprises are classified into seven industries including Agriculture, Material, Industry, Real estate and Construction, Energy, Consumer, and Service. The paper also analyzes the variation of the effects among companies, focusing on differences in revenue and capital structure. The results show that the COVID-19 pandemic negatively affects business performance. In addition, the empirical findings indicate that revenue and debt decreasing can cause deterioration of firm performance during the pandemic period. The decrease in revenue has a direct impact on firm profitability. The reduction of debt levels affects the corporate leverage leading to adverse effects on firm performance. The negative effect is more pronounced for companies in some specific sectors including industry, real estate, construction, consumption, and services.

• 한국유기농업학회지
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• 제30권2호
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• pp.171-189
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• 2022

This study analyzed the effect of purchase competence on purchasing performance when purchasing eco-friendly food ingredients from school nutrition teachers. To this end, 131 copies surveyed for school nutrition teachers in the survey area were used for analysis. As a result of the analysis, the verification of the difference between purchase competence and purchase performance according to the general characteristics of school nutrition teachers showed significant differences according to age. In addition, the general characteristics of nutrition teachers and the effect of purchase competence on purchasing performance had a positive (+) effect on purchasing performance by Attitude, Knowledge, and communication among purchase competence. In this respect, it is judged that it is necessary to form an organic relationship between the supplier of eco-friendly food ingredients and nutrition teachers in school meals.

• Steel and Composite Structures
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• 제51권3호
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• pp.289-304
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• 2024

The seismic performance of traditional steel frame-shear wall structures was significantly improved by the application of self-centering steel-reinforced concrete (SRC) wall-panel structures in the steel frames. This novel resilience functionality can rapidly restore the structure after an earthquake. The presented steel frame with steel-reinforced concrete self-centering wall-panel structures (SF-SCW) was validated, indicating its excellent seismic performance. The seismic design method based on bear capacity cannot correctly predict the elastic-plastic performance of the structure, especially certain weak floors that might be caused by a major fracture. A four-level seismic performance index, including intact function, continued utilization, life safety, and near-collapse, was established to achieve the ideal failure mode. The seismic design method, based on structural displacement, was proposed by considering performance objectives of the different seismic action levels. The pushover analysis of a six-floor SF-SCW structure was carried out under the proposed design method and the results showed that this six-floor structure could achieve the predicted failure mode.

• Computers and Concrete
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• 제17권2호
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• pp.281-294
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• 2016

The increased awareness of electromagnetic wave hazards has prompted studies on electromagnetic shielding using conductive materials in the construction industry. Previous studies have explored the effects of the types of conductive materials and their mix proportions on the electromagnetic shielding performance; however, there has been insufficient research on the effect of the geometry of the conductive materials on the electromagnetic shielding performance. Therefore, in this study, the dependence of the electromagnetic shielding performance on the cross-sectional geometry, diameter and length of fibers was investigated. The results showed that the electromagnetic shielding performance improved when the fiber length increased or the diameter decreased, but the effect of the cross-sectional geometry of the fibers was smaller than the effect of the fiber spacing factor.