• Journal of Practical Engineering Education
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• v.14 no.2
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• pp.267-277
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• 2022

Achievement at university is recognized in a comprehensive sense as the level of qualitative change and development that students have embodied as a result of their experience in university education. Therefore, the academic achievement of university students will be given meaning in cooperation with the historical and social demands for diverse human resources such as creativity, leadership, and global ability, but it is practically an indicator of the outcome of university education. Measurement of academic achievement by such credits involves many problems, but in particular, standardization of academic achievement by credits based on evaluation methods, contents, and university rankings is a very difficult problem. In this study, we present a model that uses machine learning techniques to predict whether or not academic achievement is excellent for D-University graduates. The variables used were analyzed using up to 96 personal information and bachelor's information such as graduation year, department number, department name, etc., but when establishing a future education course, only the data after enrollment works effectively. Therefore, the items to be analyzed are limited to the recommended ability to improve the academic achievement of the department/student. In this research, we implemented an academic achievement prediction model through analysis of core abilities that reflect the philosophy, goals, human resources image, and utilized machine learning to affect the impact of the introduction of the prediction model on academic achievement. We plan to apply the results of future research to the establishment of curriculum and student guidance conducted in the department to establish a basis for improving academic achievement.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.12
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• pp.889-898
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• 2022

In this paper, parallel computing method on the three-dimensional electromagnetic field is proposed. The present electromagnetic scattering analysis is conducted based on the time-harmonic vector wave equation and the finite element method. The edge-based element and 2^nd -order absorbing boundary condition are used. Parallelization of the elemental numerical integration and the matrix assemblage is accomplished by allocating the partitioned finite element subdomain for each processor. The graph partitioning library, METIS, is employed for the subdomain generation. The large sparse matrix computation is conducted by MUMPS, which is the parallel computing library based on the multi-frontal method. The accuracy of the present program is validated by the comparison against the Mie-series analytical solution and the results by ANSYS HFSS. In addition, the scalability is verified by measuring the speed-up in terms of the number of processors used. The present electromagnetic scattering analysis is performed for a perfect electric conductor sphere, isotropic/anisotropic dielectric sphere, and the missile configuration. The algorithm of the present program will be applied to the finite element and tearing method, aiming for the further extended parallel computing performance.

• The Journal of the Convergence on Culture Technology
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• v.8 no.5
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• pp.207-218
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• 2022

This study, to confirm the mediating effect of knee pain on cognitive functions and depression in older adults, and as an interdisciplinary research between the physical and psychological mechanisms, confirmed the identifying group differences by gender, age, and educational attainment of older adults, and aimed to research the improvement of cognitive functions, which is a main factor of dementia's risk prediction. The analysis data was from the 8th Korean Longitudinal Study of Ageing (KLoSA) in 2020, and the research model was verified using Process macro and model #4. The main analysis results are as follows. First, depression partially mediation effect of knee pain on cognitive functions. Second, the mediation effect of depression by gender was significant, but the direct effect in the male older adults group was twice that in the female older adults; the indirect effect did not vary significantly based on gender. Third, the mediating effect of depression by age was relatively greater in the old-old aged group than in the young-old aged one. Fourth, as for the mediating effect of depression according to the classification of educational attainment, the mediating effect was not significant in the group with a college degree or higher education but was significant in the remaining three sub-groups. Based on the results, this study makes implications for the need for active intervention strategies to improve cognitive functions, focusing on group differences by gender, age, and educational attainment in the management of knee pain and depression.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.4
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• pp.555-562
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• 2022

This study measured and analyzed the propagation characteristics at frequencies 6, 10, and 17 GHz to discover the new propagation demands in a semi-basement indoor corridor environment for meeting the 4th industrial revolution requirements. The measured indoor environment is a straight corridor consisting of three lecture rooms and glass windows on the outside. The measurement scenario development and measurement system were constructed to match this environment. The transmitting antenna was fixed, and the frequency domain and time domain propagation characteristics were measured and analyzed in the line-of-sight environment based on the distance of the receiving antenna location. In the frequency domain, reliability was determined by the parameters of the floating intercept (FI) path loss model and an R-squared value of 0.5 or more. In the time domain, the root mean square (RMS) delay spread and the cumulative probability of K-factor were used to determine that 6 GHz had high propagation power and 17 GHz had low propagation power. These research results will be effective in providing ultra-connection and ultra-delay artificial intelligence services for WIFI 6, 5G, and future systems in a semi-basement indoor corridor environment.

• Environmental and Resource Economics Review
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• v.31 no.2
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• pp.205-232
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• 2022

This study analyzes the effect of the 2^nd pilot test of Tiime of Use (TOU) pricing for Korean households using a two-level electricity demand model. The test, implemented from May to September 2021, was conducted to compare the effects of two TOU pricing rates and the standard rates for households living in apartment and detached house in 7 provinces of Korea. Based on the data on electricity consumption during the test period and during the same period last year of the 1,292 participants and their socio-economic characteristics, this study analyzes (1) whether the relative demand across periods has changed in response to hourly price changes and (2) whether the price responsiveness of daily consumption has changed after the introduction of TOU pricing. The results show that both types of TOU pricing affect neither the relative demand across periods nor the price responsiveness of daily consumption. The reason behind the results could be related to the level of TOU pricing rates and the periodical classification, which were not sufficient to induce changes in the participants' electricity demand patterns.

• Korean Chemical Engineering Research
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• v.60 no.3
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• pp.363-370
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• 2022

In this paper, an estimation algorithm for state of charge (SOC) was applied using an equivalent circuit model (ECM) and an Extended Kalman Filter (EKF) to improve the estimation accuracy of the battery system states. In particular, an observer was designed to estimate SOC along with the aged capacity. In the case of the fresh battery, when SOC was estimated by Kalman Filter (KF), the mean absolute percentage error (MAPE) was 0.27% which was smaller than MAPE of 1.43% when the SOC was calculated by the model without the observer. In the driving mode of the vehicle, the general KF or EKF algorithm cannot be used to estimate both SOC and capacity. Considering that the battery aging does not occur in a short period of time, a strategy of periodically estimating the battery capacity during charging was proposed. In the charging mode, since the current is fixed at some intervals, a strategy for estimating the capacity along with the SOC in this situation was suggested. When the current was fixed, MAPE of SOC estimation was 0.54%, and the MAPE of capacity estimation was 2.24%. Since the current is fixed when charging, it is feasible to estimate the battery capacity and SOC simultaneously using the general EKF. This method can be used to periodically perform battery capacity correction when charging the battery. When driving, the SOC can be estimated using EKF with the corrected capacity.

• Journal of Aerospace System Engineering
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• v.16 no.4
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• pp.88-94
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• 2022

The vibration mode measurement test measures the natural vibration characteristics of the target specimen. The measured natural mode characteristics are compared with the numerical analysis result to verify the reliability of the numerical analysis. If necessary, it is used to supplement the numerical analysis model of the specimen used for the dynamic characteristic analysis. In this paper, the natural frequency and natural mode of the external fuel tank are respectively obtained through the vibration mode measurement test and the numerical analysis, using the finite element model. The results are compared to verify the reliability of the numerical analysis model of the external fuel tank to apply to the entire aircraft model. To measure the vibration mode of the test specimen, a bungee cord was used, to simulate the free boundary condition for the test specimen. And, 3-axis accelerometers were installed on the test specimen. The response characteristics of the test specimen were measured, by excitation with an impact hammer. As a result of the test, after performing the frequency response analysis on the response acceleration, the natural frequency of the test specimen and its vibration mode were confirmed. The reliability of the numerical analysis model was verified by comparing the frequency and vibration mode, obtained through the test and the numerical analysis.

• Clean Technology
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• v.28 no.2
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• pp.193-200
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• 2022

The term environmental, social and governance (ESG) was first used in the 2003 United Nations Environmental Programme Finance Initiative (UNEP FI). Among the three areas of ESG, environment refers to the impact of companies on the environment. Environmental factors address climate change policies and attempts to reduce emissions, waste and natural resource consumption. Social factors refer to the direction in which a company can improve the social impact of stakeholder includes employees, customers, communities, and governments involved in direct or indirect interaction with the organization itself and the company. Governance factors refer to stakeholders who make major decisions, the composition of the board of directors, their diversity and independence, and the internal policies that set limits and expectations for decision-making. Research related to ESG management is part of corporate social responsibility, sustainability, corporate or financial performance, and social responsibility investment. Through case studies and data-based empirical studies, it was confirmed that ESG management companies had positive results for most of the ESG related fields. Through literature analysis of domestic and international ESG history, introduction background, and management performance, this paper presents theoretical, practical implications by confirming that ESG's introduction and operation strategies are strong competitive strategies that directly affect corporate growth by creating attractive factors.

• Membrane Journal
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• v.32 no.5
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• pp.283-291
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• 2022

Hydrogen energy has received much attention as a solution to the supply of renewable energy and to respond to climate change. Hydrogen is the most suitable candidate of storing unused electric power in a large-capacity long cycle. Among the technologies for producing hydrogen, water electrolysis is known as an eco-friendly hydrogen production technology that produces hydrogen without carbon dioxide generation by water splitting reaction. Membranes in water electrolysis system physically separate the anode and the cathode, but also prevent mixing of generated hydrogen and oxygen gases and facilitate ion transfer to complete circuit. In particular, the key to next-generation anion exchange membrane that can compensate for the shortcomings of conventional water electrolysis technologies is to develop high performance anion exchange membrane. Many studies are conducted to have high ion conductivity and excellent durability in an alkaline environment simultaneously, and various materials are being searched. In this review, we will discuss the research trends and points to move forward by looking at the research on anion exchange membranes based on commercial polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene (SEBS) block copolymers.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.37 no.2
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• pp.171-177
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• 1992

The purpose of this study was to compare the test methods for predicting field emergence of Lotus corniculatus and Trifolium pratense. Four seed lots of two herbage legumes were controlled deteriorated, accelerated aged before germination test and conductivity of each seed lot was determined. Those germination percent and conductivity of seed lots were compared with actual field emergence rate. Field emergence rate could be estimated by the controlled deterioration test ($R^2$=0.687), by the accelerated aging test ($R^2$=0.260), and by the conductivity test ($R^2$=0.238). A multiple regression equation for predicting field emergence rate(equation omitted) was estimated as (equation omitted)=-198.16 ＋ 2.3493X$_1$-1.5564X$_2$ ＋ 1.9812X$_3$where X$_1$, percent germination of controlled deterioration test ; X$_2$, percent germination of accelerated aging test; and X$_3$, conductivity of solute leakage in the conductivity test. Conclusively, unless multiple tests are not available, the controlled deterioration test was comparatively high efficient for predicting field emergence rate, however, the combined measurements of those three tests can enhance the efficiency.