• Journal of Auto-vehicle Safety Association
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• v.9 no.4
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• pp.38-47
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• 2017

With automobiles sharply increasing worldwide, we are faced with serious social problems such as traffic accidents, traffic jams, environmental pollution, and economic inefficiency. In response, research on ITS is promoted mainly by regions with advanced automotive industry such as the US, Europe, and Japan. While Korea is working to get ahead to take global market through developing and turning into global standards systems related to ASV(Advanced Safety Vehicle), the country is not excellently prepared for such projects. The purpose of ACC is to control the vehicle's longitudinal speed and distance and minimize driver workload. Such a system should be useful in preventing accidents, as it reduces driver workload in the 21st-century world of telematics created by the development of automobile culture industry. In this light, the thesis presents a method to test and evaluate ACC system and a mathematical method to assess distance. Furthermore, for the proposed test and evaluation, theoretical values are tested with vehicle test and a database is acquired, by using vehicles equipped with an ACC system. We proposed the scenarios suitable for the domestic environment and conducted the actual road test. Theoretical evaluation criteria for developing ACC system may be employed and scenario-specific evaluation methods may find their useful application through testing the formula proposed by comparing the database and the mathematical method. and, many companies are expected to utilize the scenario in the developing stage of ACC, and be able to employ as a verification method by harnessing theoretical formula before a road test.

• Journal of Elementary Mathematics Education in Korea
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• v.22 no.1
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• pp.47-67
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• 2018

The purpose of this study is to develop an elementary mathematics education program for social justice. In the two years of research including literature review and development of a teaching model, forty 6th grade elementary students at two schools in Seoul participated as participants for verification of the effectiveness of the program. Parents' SES in each group is in the high and average levels, respectively. The students participated in 12 mathematical classes for social justice, and the effects of mathematics education for social justice were tested by using mixed method. As a result of the study, students' perceptions of mathematics and tendency toward mathematics were changed positively. The results of this study showed that students' perceptions on mathematics and tendency toward mathematics were influenced by individual ability, inclination, and condition rather than parents' socio-economic environments. It is necessary to develop high qualified and diverse mathematical materials for social justice in order to cultivate creative convergence ability that flexibly copes with future society. It is also necessary for teachers to look at mathematics education in a broader and deeper perspective such as seeing mathematics with humanistic imagination.

• Journal of Korean Society of Water and Wastewater
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• v.28 no.6
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• pp.735-745
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• 2014

This paper presents PKES(PuKyung -Excel based Simulator) for WWTPs(wastewater treatment plants) by using MS Excel and VBA(Visual Basic for Application). PKES is a user-friendly simulator for the design and optimization of the whole plant including biological and physico-chemical processes for the wastewater and sludge treatment. PKES calculates the performance under steady or dynamic state and allows changing the mathematical model by the user. Mathematical model implemented in PKES is a improved integration model based on ASM2d and ADM1 for simulation of AS(activated sludge) and AD(anaerobic digestion). Gaseous components of $N_2$, $N_2O$, $CO_2$ and $CH_4$ are added for estimation of GHGs(greenhouse gases) emission. The simulation results for comparison between PKES and Aquasim(EAWAG) showed about the same effluent concentrations. As a result of verification using by measured data of BOD, TSS, TN and TP for 2 years of operation, calculated effluent concentrations were similar to measured effluent concentrations. The values of average RMSE(root mean square error) were 1.9, 0.8, 1.6 and 0.2 mg/L for BOD, TSS, TN and TP, respectively. Total GHGs emission of WWTP calculated by PKES was 138.5 ton-$CO_2$/day and GHGs emissions of $N_2O$, $CO_2$ and $CH_4$ were calculated at 21.7, 28.9 and 87.9 ton-$CO_2$/day, respectively. GHGs emission of activated sludge was 32.5 % and that of anaerobic digestion was 67.5 %.

• Analytical Science and Technology
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• v.8 no.4
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• pp.759-770
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• 1995

By extensive studies with the quantitative status of the mineral constituents of thousands of water samples, it was found that almost in all natural waters irrespective of the surface or sub-surface sources, minimum 99.5% of the total amount of the cationic constituents are generally the contributions of 3 commonly present parameters viz. Ca, Mg and Na and that of the anionic species are same and contributed by $HCO_3$, Cl and $SO_4$ only. In the field of water works, all these major mineral substances are conventionally measured as their individual ions. But till now, no reliable and generalised methods or rules have been developed for the determination of the exact kinds of the individual salt components and their amounts from these ionic constituents normally present in water. As salt content, only the TDS (Total Dissolved Solids) parameter is frequently measured by evaporation of the water sample. But TDS can tell nothing about the kinds and amounts of the individual salts present in it. Considering the analytical importance of the estimation of the mineral substances as their individual salts, some generalised mathematical models have been developed by this research which are based on the 'hypothetical order of chemical combinations' as may occur among the ionic constituents. With the help of these models, one can easily assume the most probable salts with approximate quantities derived from the ionic constituents. In addition, approximate amount of Na content can also be estimated mathematically with simultaneous verification of the correctness of the water analysis results. The models are stated in this paper with practical illustrations and descriptions of the method of applications.

• Journal of the Society of Naval Architects of Korea
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• v.31 no.3
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• pp.47-58
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• 1994

Theoretical calculations are carried out for the estimation of linear maneuvering coefficients of a ship moving in shallow water region. Hydrodynamic forces and moments acting on a maneuvering ship are modelled based on a slender body theory, from which integro-differential equation for the unknown inner stream velocity is derived. Numerical algorithms fur solving this equation are described in detail. By considering water depth effects in the mathematical model, variations of maneuvering coefficients with water depth are studied. Programs are developed according to this method and calculations are done for Mariner, Series 60 and Wigley hull forms. For the verification of the programs, calculated results are compared with some analytic solutions and with published experimental results, which show good agreements in spite of many assumptions included in the mathematical model. It is expected that this method can be used as a preliminary tool for the estimation of maneuverability coefficients of a ship in shallow water region at its initial design stage.

• The Mathematical Education
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• v.58 no.3
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• pp.459-481
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• 2019

This study aims to investigate students' statistical thinking through statistical processes in different instructional settings: Teacher-centered instruction vs. student-centered learning. We first developed instructional materials that allowed students to experience all the processes of statistics, including data collection, data analysis, data representation, and interpretation of the results. Using the instructional materials for four classes, we collected and analyzed the data from 57 seventh graders' discourse and artifacts from two different instructional settings using the analytic framework generated on the basis of literature review. The results showed that students felt difficulty particularly in the process of data collection and graph representations. In addition, even though data description has been heavily emphasized for data analysis in statistics education, it is surprisingly discovered that students had a hard time to understand the relationship between data and representations. Also, there were relationships between students' statistical thinking and instructional settings. Even though both groups of students showed difficulty in data collection and graph representations of the data, there were significant differences between the groups in terms of their performance. Whereas students from student-centered learning class outperformed in making decisions considering verification and justification, students from teacher-centered lecture class did better in problems requiring accuracy than the counterpart. The results from the study provide meaningful implications on developing curriculum and instructional methods for statistics education.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.6
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• pp.314-321
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• 2019

The Self-Adaptive Vision Correction Algorithm (SAVCA) developed in this study was suggested for improving usability by modifying four parameters (Modulation Transfer Function Rate, Astigmatic Rate, Astigmatic Factor and Compression Factor) except for Division Rate 1 and Division Rate 2 among six parameters in Vision Correction Algorithm (VCA). For verification, SAVCA was applied to two-dimensional mathematical benchmark functions (Six hump camel back / Easton and fenton) and 30-dimensional mathematical benchmark functions (Schwefel / Hyper sphere). It showed superior performance to other algorithms (Harmony Search, Water Cycle Algorithm, VCA, Genetic Algorithms with Floating-point representation, Shuffled Complex Evolution algorithm and Modified Shuffled Complex Evolution). Finally, SAVCA showed the best results in the engineering problem (speed reducer design). SAVCA, which has not been subjected to complicated parameter adjustment procedures, will be applicable in various fields.

• International Journal of Contents
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• v.8 no.2
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• pp.52-59
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• 2012

This study uses digital imaging and communications in medicine (DICOM) files acquired after CT scan to obtain the absorbed dose distribution inside the body by using the patient's actual anatomical data; uses geometry and tracking (Geant)4 as a way to obtain the accurate absorbed dose distribution inside the body. This method is easier to establish the radioprotection plan through estimating the absorbed dose distribution inside the body compared to the evaluation of absorbed dose using thermo-luminescence dosimeter (TLD) with inferior reliability and accuracy because many variables act on result values with respect to the evaluation of the patient's absorbed dose distribution in diagnostic imaging and the evaluation of absorbed dose using phantom; can contribute to improving reliability accuracy and reproducibility; it makes significance in that it can implement the actual patient's absorbed dose distribution, not just mere estimation using mathematical phantom or humanoid phantom. When comparing the absorbed dose in polymethly methacrylate (PMMA) phantom measured in metal oxide semiconductor field effect transistor (MOSFET) dosimeter for verification of Geant4 and the result of Geant4 simulation, there was $0.46{\pm}4.69%$ ($15{\times}15cm^2$), and $-0.75{\pm}5.19%$ ($20{\times}20cm^2$) difference according to the depth. This study, through the simulation by means of Geant4, suggests a new way to calculate the actual dose of radiation exposure of patients through DICOM interface.

• International Journal of Aeronautical and Space Sciences
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• v.14 no.1
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• pp.91-98
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• 2013

The rigorous requirements of modern spacecraft missions necessitate a precise attitude determination strategy. This paper mainly researches that, based on three space-borne attitude sensors: 3-axis rate gyros, 3-antenna GPS receiver and star-sensor. To obtain global attitude estimation after an information fusion process, a feedback-involved Federated Kalman Filter (FKF), consisting of two subsystem Kalman filters (Gyros/GPS and Gyros/Star-sensor), is established. In these filters, the state equation is implemented according to the spacecraft's kinematic attitude model, while the residual error models of GPS and star-sensor observed attitude are utilized, to establish two observation equations, respectively. Taking the sensors' different update rates into account, these two subsystem filters are conducted under a variable step size state prediction method. To improve the fault tolerant capacity of the attitude determination system, this paper designs malfunction warning factors, based on the principle of ${\chi}^2$ residual verification. Mathematical simulation indicates that the information fusion strategy overwhelms the disadvantages of each sensor, acquiring global attitude estimation with precision at a 2-arcsecs level. Although a subsystem encounters malfunction, FKF still reaches precise and stable accuracy. In this process, malfunction warning factors advice malfunctions correctly and effectively.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.159-162
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• 2005

Urban flooding is usually caused by the surcharge of storm sewers. For that reason, domestic studies about urban flooding are concentrated on the simulation of urban drainage system. However these approaches that find the pipes which have insufficient drainage capacity are very approximate and unreasonable ways. In this study, an accurate mathematical modeling is developed to analyze the impacts of an urban inundation for both flood prevention and flood-loss reduction planning and it is verified by using the simulation of July 2001 flooding in Seoul. The result of this study can be used to construct fundamental data for a flood control plan and establish a urban flood forecasting/warning system.