• Journal of the Korean School Mathematics Society
• /
• v.23 no.3
• /
• pp.299-321
• /
• 2020

PISA, organized by the OECD, started with the worries about what competencies students need in preparation for a changing future society. Starting with the first main survey in 2000, PISA, which was administered every three years, is preparing for the eighth cycle. PISA 2022 is a cycle in which mathematics becomes the main domain in 10 years, and the definition of mathematics literacy, mathematical framework, and illustrative examples were released. Therefore, in this study, the definition of PISA mathematics literacy and the trends on the mathematical framework were examined, and the characteristics of the illustrative examples introduced together with the PISA 2022 mathematical framework were analyzed. Through this, implications were drawn for the successful implementation of the 2015 revised curriculum and assessment.

• Wind and Structures
• /
• v.34 no.1
• /
• pp.101-113
• /
• 2022

We experimentally investigate the high-Reynolds flow around a rectangular cylinder of aspect ratio 5:1. This configuration is the object of the international BARC benchmark. Wind tunnel tests have been carried out for the flow at zero angle of attack and a Reynolds number, based on the crossflow cylinder length and on the freestream velocity, equal, to 40 000. Velocity measurements are obtained by using hot-wire anemometry along 50 different cross-flow traverses on the cylinder side and in the near wake. Differential pressure measurements are acquired on multiple streamwise sections of the model. The obtained measurements are in a good agreement with the state-of-the-art experiments. For the first time among the several contributions to the BARC benchmark, detailed flow measurements are acquired in the region near the cylinder side and in the near-wake flow. The edges and the thickness of the shear layers detaching from the upstream edges are derived from velocity measurements. Furthermore, we compute the flow frequencies characterizing the roll-up of the shear layers, the evolution of vortical structures near the cylinder side and the vortex shedding in the wake.

• Journal of the Korean Chemical Society
• /
• v.66 no.1
• /
• pp.31-41
• /
• 2022

The purpose of this study is to draw implications for future Korean science education by analyzing the PISA 2015 science teacher questionnaire. To this end, descriptive statistics and difference tests were conducted for each questionnaire item, using raw data from science teacher surveys in Korea, the United States, and China. As a result of the analysis, first, the perception that Korean science teachers should participate in professional development activities was lower than that of comparative countries, and it was found that improvement was needed in the practice of adaptive instruction and various evaluation methods. Second, although Korean science teachers were generally satisfied with their jobs, the response that they were hindered in science education activities due to limitations in various resources at their current school was relatively higher than that of comparative countries. Third, scientific inquiry was less emphasized in science curriculum and science class in Korea, and self-efficacy in inquiry teaching process was relatively low. Fourth, in Korea, it was found that there were fewer classes for discussion and using ICT in science classes.

• Journal of The Korean Association of Information Education
• /
• v.26 no.5
• /
• pp.385-396
• /
• 2022

The 2022 revised curriculum emphasized basic literacy, which consists of language, numeracy, and digital literacy. This digital literacy is being presented in the curriculum as a goal for cultivating digital literacy in various countries. Therefore, this study looked at the curriculum of countries with high digital literacy among students. And PISA 2018 data analysis was conducted on ICT elements of students by country. Specifically, one-way ANOVA, correlation analysis, and confirmatory factor analysis were performed for each ICT element for country-by-country comparison. As a result, when organizing the curriculum related to digital literacy, it is necessary to organize it earlier than the present time. In addition, it was found that it was necessary to consider the contents to increase the usability in school.

• Wind and Structures
• /
• v.34 no.1
• /
• pp.115-125
• /
• 2022

The high-Reynolds number flow around a rectangular cylinder, having streamwise to crossflow length ratio equal to 5 is analyzed in the present paper. The flow is characterized by shear-layer separation from the upstream edges. Vortical structures of different size form from the roll-up of these shear layers, move downstream and interact with the classical vortex shedding further downstream in the wake. The corresponding mean flow is characterized by a recirculation region along the lateral surface of the cylinder, ending by mean flow reattachment close to the trailing edge. The mean flow features on the cylinder side have been shown to be highly sensitive to set-up parameters both in numerical simulations and in experiments. The results of 21 Large Eddy Simulations (LES) are analyzed herein to highlight the impact of the lateral mean recirculation characteristics on the near-wake flow features and on some bulk quantities. The considered simulations have been carried out at Reynolds number Re=DU_∞/ν=40 000, being D the crossflow dimension, U_∞ the freestream velocity and ν the kinematic viscosity of air; the flow is set to have zero angle of attack. Some simulations are carried out with sharp edges (Mariotti et al. 2017), others with different values of the rounding of the upstream edges (Rocchio et al. 2020) and an additional LES is carried out to match the value of the roundness of the upstream edges in the experiments in Pasqualetto et al. (2022). The dimensions of the mean recirculation zone vary considerably in these simulations, allowing us to single out meaningful trends. The streamwise length of the lateral mean recirculation and the streamwise distance from the upstream edge of its center are the parameters controlling the considered quantities. The wake width increases linearly with these parameters, while the vortex-shedding non-dimensional frequency shows a linear decrease. The drag coefficient also linearly decreases with increasing the recirculation length and this is due to a reduction of the suctions on the base. However, the overall variation of C_D is small. Finally, a significant, and once again linear, increase of the fluctuations of the lift coefficient is found for increasing the mean recirculation streamwise length.

• Journal of Veterinary Science
• /
• v.23 no.6
• /
• pp.82.1-82.6
• /
• 2022

Domestic poultry are among the non-target species of exposure to fipronil, but limited information is available on the metabolic effects of fipronil exposure in avian. We investigated the comparative capacity of in vitro biotransformation of fipronil among chicken, duck, quail, goose, and rat. Interspecies differences in kinetic parameters were observed; the clearance rate calculations (Vmax/Km) indicated that chicken and duck are more efficient in the cytochrome P450-mediated metabolism of fipronil to sulfone than quail, goose and rat. The lower hepatic clearance of fipronil in quail, goose and rat, suggested that fipronil sulfone may serve as a biomarker to indicate fipronil exposure in these species.

• Education of Primary School Mathematics
• /
• v.25 no.3
• /
• pp.251-278
• /
• 2022

The purpose of this study is to obtain implications for mathematical education by analyzing how the multiplication and division of decimal numbers are presented in the elementary mathematics textbooks in Korea, Japan, Singapore, and Finland. Compared to the fact that students often have misconceptions about multiplication and division of decimal numbers, there have been not many comparative studies in recent elementary mathematics textbooks. For this study, we selected elementary mathematics textbooks those are widely used in Japan, Singapore, and Finland along with Korean elementary mathematics textbooks. We chose the textbooks because the students in the selected countries have scored high in international achievement studies such as TIMSS and PISA. The analysis was examined in terms of elementary mathematics curriculum related to multiplication and division of decimal numbers, introduction and content, real-life situations, use of visual models, and formalization methods of algorithms. As a result of the study, the mathematics curricula related to multiplication and division of decimal numbers includes estimation in Korea and Finland, while Japan and Singapore emphasize real-life connections more, and Finland completes the operations in secondary schools. The introduction and content are intensively provided in a short period of time or distributed in various grades and semesters. The real-life situations are presented in a simple sentence format in all countries, and the use of visual models or formalization of algorithms is linked to the operations of natural numbers in unit conversions. Suggestions were made for textbook development and teacher training programs.

• Nuclear Engineering and Technology
• /
• v.55 no.8
• /
• pp.3102-3113
• /
• 2023

Following the Fukushima nuclear disaster, the simulation of accidents in the spent fuel pool has become more noticeable. Despite the low amount of decay heat power, the consequences of the accidents in a spent fuel pool (SFP) can be severe due to the high content of long-lived radionuclides and lack of protection by the pressure vessel. In this study, the loss-of-cooling accident (LOFA) for the VVER-1000/V446 spent fuel pool is simulated by employing RELAP5 and MELCOR 1.8.6 as the best estimate and severe accident analysis codes, respectively. For two cases with different total power levels, decay heat of spent fuels is calculated by ORIGEN-II code. For modeling SFP of a VVER-1000, a qualified nodalizations are considered in both codes. During LOFA in SFP, the key sequences such as heating up of the pool water, boiling and reducing the water level, uncovering the spent fuels, increasing the temperature of the spent fuels, starting oxidation process (generating Hydrogen and extra power), the onset of fuel melting, and finally releasing radionuclides are studied for both cases. The obtained results show a reasonable consistency between the RELAP5 and MELCOR codes, especially before starting the oxidation process.

• Nuclear Engineering and Technology
• /
• v.56 no.3
• /
• pp.993-1001
• /
• 2024

The TANDEM project is a European initiative funded under the EURATOM program. The project started on September 2022 and has a duration of 36 months. TANDEM stands for Small Modular ReacTor for a European sAfe aNd Decarbonized Energy Mix. Small Modular Reactors (SMRs) can be hybridized with other energy sources, storage systems and energy conversion applications to provide electricity, heat and hydrogen. Hybrid energy systems have the potential to strongly contribute to the energy decarbonization targeting carbon-neutrality in Europe by 2050. However, the integration of nuclear reactors, particularly SMRs, in hybrid energy systems, is a new R&D topic to be investigated. In this context, the TANDEM project aims to develop assessments and tools to facilitate the safe and efficient integration of SMRs into low-carbon hybrid energy systems. An open-source "TANDEM" model library of hybrid system components will be developed in Modelica language which, by coupling, will extend the capabilities of existing tools implemented in the project. The project proposes to specifically address the safety issues of SMRs related to their integration into hybrid energy systems, involving specific interactions between SMRs and the rest of the hybrid systems; new initiating events may have to be considered in the safety approach. TANDEM will study two hybrid systems covering the main trends of the European energy policy and market evolution at 2035's horizon: a district heating network and power supply in a large urban area, and an energy hub serving energy conversion systems, including hydrogen production; the energy hub is inspired from a harbor-like infrastructure. TANDEM will provide assessments on SMR safety, hybrid system operationality and techno-economics. Societal considerations will also be encased by analyzing European citizen engagement in SMR technology safety.

• Journal of The Korean Association For Science Education
• /
• v.42 no.1
• /
• pp.149-160
• /
• 2022

Comparative studies using large-scale data such as TIMSS, PIRLS, and PISA inform us of the effectiveness of each educational system. Even though samples in the large-scale studies were representative, admitting potential discrepancy when applying the findings of the large-scale studies to local educational system is still needed. This study examines the structural relationship among students' attitude towards science, learning support from teachers, school life, and science academic achievement with both large-scale data and local comparative study data utilizing same variables. Responses on the TIMSS 2019 of 5,554 Korean seventh-grade students and National Assessment of Educational Achievement (NAEA) 2019 of 6,365 third-grade middle school students were used. The results indicate that: a) school life did not affect the science achievements in both data. However, in NAEA 2019, students' attitude mediated the relationship between school life and science achievement; b) learning support from teachers had a significant impact on TIMSS science achievements, and also had positive effect on achievement through students' attitude in TIMSS. On the other hand, learning support had a positive effect on achievement only when student's attitude mediated the relationship in NAEA; c) students 'attitude toward science had positive effect on science achievement on both data; d) the impact of gender was different on school life, academic achievement, students 'attitude towards science, and learning support from teachers on both data; and e) the impact of the number of books differed as well. There were differences in results between the international and domestic research, which inform us that we need to pay attention when interpreting the domestic environment through the results of international research.