• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.5
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• pp.398-405
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• 2014

Recently the embedded software has been widely applied to the safety-critical systems in aviation and defense industries, therefore, the higher level of reliability, availability and fault tolerance has become a key factor for its implementation into the systems. The integrity of the software can be verified using the static analysis tools. And recent developed static analysis tool can evaluate code integrity through the mathematical analysis method. In this paper we detect the autocode error and violation of coding rules using the formal verification tool, Polyspace(R). And the fundamental errors on the flight control law model have been detected and corrected using the formal verification results. As a result of verification process, FBW helicopter control law autocode can ensure code integrity.

• Steel and Composite Structures
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• v.21 no.5
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• pp.1031-1043
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• 2016

Optimization of the construction scheme of the cable-strut tensile structure based on error sensitivity analysis is studied in this paper. First, the element length was extracted as a fundamental variable, and the relationship between element length change and element internal force was established. By setting all pre-stresses in active cables to zero, the equation between the pre-stress deviation in the passive cables and the element length error was obtained to analyze and evaluate the error effects under different construction schemes. Afterwards, based on the probability statistics theory, the mathematical model of element length error is set up. The statistical features of the pre-stress deviation were achieved. Finally, a cable-strut tensile structure model with a diameter of 5.0 m was fabricated. The element length errors are simulated by adjusting the element length, and each member in one symmetrical unit was elongated by 3 mm to explore the error sensitivity of each type of element. The numerical analysis of error sensitivity was also carried out by the FEA model in ANSYS software, where the element length change was simulated by implementing appropriate temperature changes. The theoretical analysis and experimental results both indicated that different elements had different error sensitivities. Likewise, different construction schemes had different construction precisions, and the optimal construction scheme should be chosen for the real construction projects to achieve lower error effects, lower cost and greater convenience.

• Journal of the Korean Institute of Intelligent Systems
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• v.8 no.6
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• pp.37-47
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• 1998

This paper proposes a controller design method using the evolutionary computation algorithm and the fuzzy logic to control the wafer temperature in rapid thermal processing. First, we design the feedforward static controller to provide the control powers of the lamps for the given steady state temperature. Second, the feedforward dynamic controller is designed for the additional control powers to achieve a given transient response. These feedforward controllers are implemented by using the fuzzy logic to act as a global nonlinear controller over a wide range of operating points. The parameters of these controllers are optimized by using the evolutionary computation algorithm so that it can be used when the mathematical model is not available. In addition, the feedback error controller is introduced to compensate the feedforward controllers when there exist disturbances and modeling errors. The gain of feedback error controller is also obtained by the evolutionary computation algorithm. Through simulations, we verify the proposed control system can give a satisfactory performance.

• School Mathematics
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• v.6 no.4
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• pp.345-359
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• 2004

Many researchers have studied students' error patterns in learning mathematics but the results haven't much effected on teaching situation. This paper is to find out how the results have been reflected on 6th and 7th Korean elementary school mathematics textbooks, workbooks, and teachers' guide books. The focuses of analysis are the four; (a)Type of materials, (b)Type of problems, (c)Type of errors and number of rela- ted problems, and (d)organization and explanation type. Results indicate that both 6th and 7th materials don't use effectively students' error patterns to teach computation, in particular, 7th textbooks scarcely treat them. It suggests that we should grope a way to use the fruitful results of this area to teach mathematics effectively.

• Journal of Elementary Mathematics Education in Korea
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• v.18 no.2
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• pp.297-318
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• 2014

This study is designed for helping elementary school teachers have an insight into making or choosing questions of descriptive assessment in mathematics. For this, it is analyzed 30 descriptive mathematical questions produced by Gyeonggi Provincial Office of Education in 2011 and 2012 and 3rd to 6th grade students' papers marked by their teachers in charge from 2 elementary schools located in Gyeonggi Province. The main focus of analysis is the errors of students' answers and teachers' marking not from their own mistakes but from the defects of questions themselves. As a result of analysis, 7 cases of problematic situations are induced and they are reorganized into 3 categories as follow: i) case of not performing unique purpose of descriptive assessment, ii) case of inducing the problem of fairness of grading, iii) case of leading students erroneous direction.

• Journal of Educational Research in Mathematics
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• v.25 no.3
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• pp.381-405
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• 2015

The nature of school mathematics has not been asked from the epistemological perspective. In this paper, I compare two dominant perspectives of school mathematics: ethnomathematics and didactical transposition theory. Then, I show that there exist some examples from Old Babylonian (OB) mathematics, which is considered as the oldest school mathematics by the recent contextualized anthropological research, cannot be explained by above two perspectives. From this, I argue that the nature of school mathematics needs to be understand from new perspective and its meaning needs to be extended to include students' and teachers' products emergent from the process of teaching and learning. From my investigation about OB school mathematics, I assume that there exist an intrinsic function of school mathematics: Linking scholarly Mathematics(M) and everyday mathematics(m). Based on my assumption, I suggest the chain of ESMPR(Educational Setting for Mathematics Practice and Readiness) and ESMCE(Educational Setting For Mathematical Creativity and Errors) as a mechanism of the function of school mathematics.

• Advances in environmental research
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• v.4 no.4
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• pp.233-246
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• 2015

High amounts of air pollution in crowded urban areas are always considered as one of the major environmental challenges especially in developing countries. Despite the errors in air pollution prediction, the forecasting of future data helps air quality management make decisions promptly and properly. We studied the air quality of the Aqdasiyeh location in Tehran using factor analysis and the Box-Jenkins time series methods. The Air Quality Control Company (AQCC) of the Municipality of Tehran monitors seven daily air quality parameters, including carbon monoxide (CO), Nitrogen Monoxide (NO), Nitrogen dioxide ($NO_2$), $NO_x$, ozone ($O_3$), particulate matter ($PM_{10}$) and sulfur dioxide ($SO_2$). We applied the AQCC data for our study. According to the results of the factor analysis, the air quality parameters were divided into two factors. The first factor included CO, $NO_2$, NO, $NO_x$, and $O_3$, and the second was $SO_2$ and $PM_{10}$. Subsequently, the Box- Jenkins time series was applied to the two mentioned factors. The results of the statistical testing and comparison of the factor data with the predicted data indicated Auto Regressive Integrated Moving Average (0, 0, 1) was appropriate for the first factor, and ARIMA (1, 0, 1) was proper for the second one. The coefficient of determination between the factor data and the predicted data for both models were 0.98 and 0.983 which may indicate the accuracy of the models. The application of these methods could be beneficial for the reduction of developing numbers of mathematical modeling.

• Journal of Advanced Navigation Technology
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• v.2 no.2
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• pp.75-83
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• 1998

This paper presents a low cost and high accuracy integrated Global Positioning System (GPS)/dead reckoning (DR) system. The integrated GPS/DR system is capable of providing highly accurate position data in real-time or in post processing. Based on the analysis of the main error source affecting the DR measurements, an eight-state mathematical model for the integrated system has been developed to represent these errors. This eight-state model has been used to build a nonlinear filter for the estimation of the state vector at every epoch when DR measurements are available. The accuracy of the system has been evaluated using 1Hz DR measurements and 3Hz continuous GPS position estimates. Through numerical simulation the system performance during periods with GPS outage has been investigated by comparing two different noise models. While one model is the position estimation filter containing a single noise model, the other filter includes two-level noise model. The simulation results have shown that the estimation filter containing two-level noise model for computing the position error of the integrated GPS/DR system yields better performance than that the filter including the single-level noise model does.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.6
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• pp.612-619
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• 2004

Servo motor systems with ball-screw and timing-belt are widely used in NC, robot, FA and industrial applications. However, the nonlinear friction torque and damping effect in machine elements reduce the control performance. Especially tracking errors in trajectory control and very low velocity control range are serious due to the break-away friction and Stribeck effects. In this paper, a new double speed controller is proposed for compensation of the nonlinear friction torque. The proposed double speed controller has outer speed controller and inner friction torque compensator. The proposed friction torque compensator compensates the nonlinear friction torque with actual speed and speed error information. Due to the actual information for friction torque compensator without parameters and mathematical model of motor, proposed compensator is very simple structure and the stability is very high. The proposed compensator is verified by simulation and experimental results.

• Korean Journal of Childcare and Education
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• v.11 no.3
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• pp.129-148
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• 2015

The purpose of this study was to look into trends in research concerned with children's counting in Korea. A total of 59 studies on counting including journal articles, master's & doctoral theses were analyzed in terms of the period of time, content, and research methods. The results showed that 1) ${\frac{1}{3}}$ of the total studies on counting were published in 2001~2005, 2) the most frequent content was the developmental trend of young children's counting ability and then the relation between counting ability and various mathematical competence, 3) most of the studies targeted normal early childhood children from 3~5 years old and used the quantitative method. These results showed that the domestic research on counting have limits in the research topics, subjects, and methodology. The researcher presents three suggestions for further research. Frist, topics that are not enough revealed in the previous studies, for examples, counting backwards, counting by collections such as tens, fives, twos, and counting errors in young children need to be further studied. Second, counting behavior and ability of young children under 3 years olds need to be investigated. Third, there is a need to increase the studies using qualitative methods.