• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.4
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• pp.467-473
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• 2020

Recently, the number of traffic accidents has also increased with the increase in the penetration rate of cars in Korea. In particular, not only inter-vehicle accidents but also human accidents near crosswalks are increasing, so that more attention to traffic safety around crosswalks are required. In this paper, we propose a system for predicting the safety level around the crosswalk by recognizing an approaching vehicle and estimating the speed of the vehicle using NVIDIA Jetson Nano-class edge devices. To this end, various machine learning models are trained with the information obtained from deep learning-based vehicle detection to predict the degree of risk according to the speed of an approaching vehicle. Finally, based on experiments using actual driving images and web simulation, the performance and the feasibility of the proposed system are validated.

• The Mathematical Education
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• v.60 no.1
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• pp.41-59
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• 2021

The purpose of this study is to synthesize a comprehensive and general conclusion about the effects of mathematics classes using peer tutoring on the cognitive (mathematics learning achievement) and affective domains. For this purpose, a total of 61 individual studies were meta-analyzed in this study to calculate the effect size, measuring the strength of the relationship between mathematics classes using peer tutoring and either the cognitive or affective domain. As a result of this study, it was confirmed that mathematics classes using peer tutoring generally have a medium effect size in both cognitive and affective domains. Also, it was found that level of school, type of student, learning location, class time, tutor education or prior training are significant variables that affect the impact of mathematics classes using peer tutoring on the cognitive and affective domains. These results suggest specific ideas on how to design and operate peer tutoring in school mathematics classes on the basis of different variables.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.9
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• pp.771-780
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• 2021

The space Debris laser ranging system is called to be a definite type of satellite laser ranging system that measures the distance to satellites. It is a system that performs POD (Precise Orbit Determination) by measuring time of flight by firing a laser. Distance precision can be measured in mm-level units, and it is the most precise system among existing systems. Currently, KASI has built SLR in Sejong and Geochang, and utilized SLR data to verify the precise orbits of the STSAT-2C and KOMASAT-5. In recent years, due to the fall or collision of space debris, its satellites have been threatened, and in terms of security, laser tracking of space objects is receiving great interest in order to protect their own space assets and protect the safety of the people. In this paper, a 1.5m-class main mirror was applied for the system design of a multipurpose laser tracking system that considers satellite laser ranging and space object laser tracking. System preliminary performance analysis was performed based on Link Budget analysis considering specifications of major components.

• Korean Journal of Occupational Health Nursing
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• v.30 no.3
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• pp.120-131
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• 2021

Purpose: This study aimed to compare the effects of an 8 week, self-managed, app-based and poster-based stretching program on musculoskeletal symptoms, flexibility, stretching frequency, self-efficacy, social support, and musculoskeletal disorder knowledge in small manufacturing business workers. Methods: This was a cluster randomized, two-group pretest-posttest design. Workers were assigned to either an app-based (n=20) or a poster-based (n=25) stretching intervention. Both groups received an educational class. The app group also received mobile phone text messages and an app with stretching videos, stretching alarms, stretching records, and information on musculoskeletal disorders. The poster group received workplace stretching posters. Data were collected from April to September 2018 and analyzed with the 𝑥² test, paired t-test, and independent t-test. Results: There was only a significant difference in social support. Significant increase in flexibility and musculoskeletal symptoms were noted for both groups, but social support and musculoskeletal disorder knowledge were significantly changed only in the poster group. More than half of the workers practiced stretching at least 3 times a week. Conclusion: The 8 week, self-managed, workplace stretching program was effective to increase flexibility and stretching frequency to at least 3 times a week. However, effective interventions for musculoskeletal symptoms could not be identified.

• Journal of Korean Academy of Nursing
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• v.51 no.4
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• pp.478-488
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• 2021

Purpose: This study aimed to develop and examine the effects of a prenatal program on environmental health behavior using cartoon comics among Korean pregnant women. Methods: This study used a non-equivalent control group pre-test/post-test design. The program used cartoon comics to explore environmental health behaviors during pregnancy. The program consisted of the following four components: environmental toxicants during pregnancy, avoiding particulate matter during pregnancy, environmental toxicants during baby care, and making a healthy environment for children. In total, 35 pregnant women participated in the study: 18 in the experimental group and 17 in the control group. Data collection and program adaptation were conducted between November 3, 2020 and January 19, 2021. The effect of the prenatal education program was evaluated by t-test and repeated measures ANOVA. Results: Learning experience (t = - 2.35, p = .025), feasibility (t = - 2.46, p = .019), satisfaction (t = - 2.23, p = .032) were higher in the experimental group than in the control group in the first post-test. Feasibility (t = - 2.40, p = .022) was higher in the experimental group than in the control group in the second post-test. Repeated-measures ANOVA showed significant interactions between time and group in environmental susceptibility (F = 9.31, p < .001), self-efficacy (F = 3.60, p = .033), and community behavior (F = 5.41, p = .007). Conclusion: This study demonstrates the need for a prenatal education program to promote environmental health perceptions and behavior during pregnancy. We suggest a prenatal class adopting the creative cartoon comics to promote the maternal environmental health behaviors.

• The Journal of Information Systems
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• v.31 no.1
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• pp.59-90
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• 2022

Purpose This paper presents a new method of classifying online platforms. It also explains how to apply the framework using case studies and generate new insight about platform strategies and policy development. Design/methodology/approach This paper focuses on the relationship between platforms, especially the hierarchy and power relations, and broadly classifies platforms as follows: content/services, meta information, app stores, operating systems, and cloud. Both the content/service platform and the meta information platform have matching as their main function. However, most content/services tend to collect and access information through meta-information platforms, so meta-information platforms are closer to infrastructure than content/service platforms. App store, operating system, and cloud can be said to be platforms of platforms. A small number of companies in the US and China dominate platforms of platforms, and become the recent development and regulatory targets of their respective governments. Findings We should be wary of the attempts to regulate domestic platforms by importing foreign regulations that ignore the hierarchical structure that our framework highlights. We believe that Korea's strategy to become a true platform powerhouse is clear. As one of the few countries with significant companies in the area of meta information platforms, it will be necessary to fully utilize the position and advance into the strategically important area of platforms of platforms. Furthermore, it is necessary to encourage world-class companies to appear in Korea in the app store, operating system, and cloud. To do so, the government needs to introduce promotion policies to strategically nurture such platforms rather than to regulate them.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.4
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• pp.353-358
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• 2022

Bulky iron-core potential transformers (PT) are installed in a tank of gas insulated switchgears (GIS) for a system voltage measurement in power substations. In this paper, we studied an electronic voltage transformer (EVT) embedded in a spacer for miniaturization, eco-friendliness, and performance improvement of GIS. The prototype EVT consists of a capacitive probe (CP) that can be embedded in a spacer and a voltage Follower with a high input and a low output impedance. The CP was fabricated in the form of a Flexible-PCB to acquire the insulation performance and to withstand vibration and shock during operation. Voltage ratio of the prototype EVT is about 42,270, and the frequency bandwidth of -3 dB ranges from 0.33 Hz to 3.9 MHz. The voltage ratio error evaluated at about 6%, 12% and 18% of the rated voltage of 170 kV was 0.32%, and the phase error was 12.9 minutes. These results were within the accuracy for the class 0.5 specified in IEC 60044-7 and satisfy even in ranges from 80% to 120% of the rated voltage. If the prototype EVT replaces the conventional iron-core potential transformer, it is expected that the height of the GIS could be reduced by 11% and the amount of SF₆ will be reduced by at least 10%.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.25 no.3
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• pp.17-28
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• 2022

We evaluated the effect of CO₂ offsetting by estimating changes in carbon uptake under various forest management scenarios and proposed forest management strategies to achieve carbon neutrality. Paju and Goseong, which have relatively large forest areas but different industrial characteristics, were selected for the study sites. The current state of forest distribution was analyzed using forest type maps and aerial photographs, and the amount of carbon uptake was calculated using the equation presented by the IPCC Guidelines for National Greenhouse Gas Inventories and the national emission/absorption coefficients from the Korea National Greenhouse Gas Inventory Report. As of 2015, the forest carbon absorption in Paju and Goseong was 49,931 t/yr and 94,225 t/yr, respectively, and the annual carbon absorption per unit area was 2.28 t/ha/yr and 2.16 t/ha/yr. Under the forest management scenarios, the annual maximum carbon absorption per unit area is estimated to increase to 5.68 t/ha/yr in Paju and 4.22 t/ha/yr in Goseong, and this absorption would increase further if urban forests were additionally created. Even if the current forests of Paju and Goseong are maintained as they are, emissions from electricity use can be sufficiently offset. However, by applying appropriate forest management strategies, emissions from sectors other than electricity use could be offset. This study can be applied to the establishment of carbon absorption strategies in the forest sector to achieve carbon neutrality.

• Journal of the Korean Chemical Society
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• v.66 no.5
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• pp.405-415
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• 2022

This study investigated the perceptions of high school students for 8 performance assessment methods in a chemistry teacher's class by using an explanatory sequential design. To this end, a survey was conducted with 439 students from 10 high schools, and after that, 28 students from 5 schools were interviewed to interpret the survey results. The findings were as follows: First, students were experiencing a biased assessment method rather than various performance methods. Second, intuitive confirmation, relevance to a career path, and internal growth were mentioned in the performance assessment method that felt fun, and readiness and unclear evaluation criteria were mentioned in the performance assessment method that felt difficult. Third, the students recognized that it was not an appropriate performance method if the assessment result was affected by individual abilities less relevant to the chemistry subject or the assessment criteria were unclear.

• Advances in concrete construction
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• v.13 no.1
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• pp.35-43
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• 2022

The experimental investigations into hooked-end round steel fibers (HSF) effect on the age-dependent strengths of high volume fly ash (HVFA) concrete is studied. The concrete was prepared with class F fly ash used as partial cement replacement varied from 0% to 70% on an equal weight basis. Two percentages of HSF (i.e., 0.5% and 1.5% by volume fraction) of 50 mm length were added in plain, and 50% fly ash concrete mixes. The compressive and flexural tensile strength was determined at 7, 28, 56, and 90 days. The strength results of fly ash concrete mixes with and without steel fibers were compared with the plain concrete strength. The test results indicated that the strength of fly ash concrete is comparable with the plain concrete strength and further increases with an increase in the percentage of steel fibers. The maximum flexure strength of HVFA concrete is found with 0.5% steel fibers. It is concluded that the HVFA concrete with steel fibers of 50 mm length can effectively be used in concrete construction. The analytical models are proposed to predict the age-dependent compressive and flexural tensile strength of HVFA concrete with and without HSF. The compressive and tensile strength of HVFA concrete with HSF can be predicted using these models when the 28-day compressive strength of plain concrete is known. The present study will be helpful in the design and construction of reinforced and pre-stressed concrete structures made with HVFA and HSF.