• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.5
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• pp.639-650
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• 2023

Economic development has resulted in the concentration of population and industry in the metropolitan area. Additionally, the Republic of Korea is experiencing this phenomenon, with more than half of the population living in the Seoul capital area. To alleviate this concentration of population, the Korean government implemented the new town development policy. Unfortunately, this has led to an increase in the commuting population, causing an imbalance in transportation services due to financial and policy differences in each region. This paper analyzes the level of user satisfaction with mega commuting in three aspects: mobility, accessibility, and connectivity. To objectively assess the level of user satisfaction, which is qualitative data, the Rasch Model is used to analyze the collinearity of user data. The results indicate that the level of user satisfaction differs by region, and service satisfaction with mobility is lower than that with accessibility and connectivity. Therefore, prior to the introduction of new town policies, it is necessary to develop metropolitan transportation infrastructure.

• Journal of the Korean Applied Science and Technology
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• v.40 no.2
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• pp.268-276
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• 2023

The purpose of this study is to investigate how the presence experience of virtual reality sports room class affects the intention to participate in sports activities when pleasure and immersion are experienced. For the survey, a total of 300 people, 60 copies each, were sampled for the upper grades of elementary school, and a total of 276 copies of data were used for the study, excluding 24 copies with insincere answers from among the questionnaires. The data processing used in this study was SPSS ver. 24.0 and AMOS ver. 24.0 Statistical program was used to perform confirmatory factor analysis, frequency analysis, Cronbach's α coefficient calculation, correlation analysis, and structural equation model analysis. Through this procedure, the following results were derived. First, the presence experience of the virtual reality sports room class had a positive effect on enjoyment. Second, the relationship between enjoyment and immersion in virtual reality sports room classes had a positive effect. Third, the enjoyment of the virtual reality sports room class had a positive effect on the intention to participate in sports activities. Fourth, the class immersion of the students who participated in the virtual reality sports room had a positive effect on their intention to participate in future sports activities.

• Knowledge Management Research
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• v.23 no.4
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• pp.177-205
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• 2022

Small- and medium-sized enterprises (SMEs) have strong incentives to engage in open innovation to enhance innovation efficiency and effectiveness due to their 'liability of smallness.' Previous research examined the performance effects of various open innovation practices, but whether coupled open innovation practices positively affect SMEs' firm performance is somewhat controversial. To resolve the issue, this study examined the effects of coupled open innovation activities on SMEs' firm performance using Heckman's two stage model to control endogeneity of the firms' self-selection bias in open innovation engagement. This study used the Korean Innovation Survey (KIS) 2020 collected by the Science and Technology Policy Institute (STEPI), and tested the effects of SMEs' coupled open innovation activities, R&D and non-R&D cooperation, on their innovative and financial performance indicators. The results showed that SMEs' R&D cooperation positively affects the new-to-market (NTM) product innovation only. Moreover, SMEs' non-R&D cooperation has positive effects on the product innovation, business process innovation, new-to-the-market product innovation, and new-to-firm (NTF) product innovation. However, the results showed that both R&D and non-R&D innovation cooperation activities have no significant effects on SMEs' financial performance indicators. This study contributes to research on SMEs' open innovation and provides insights for SMEs' managers and policymakers.

• The Journal of the Convergence on Culture Technology
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• v.9 no.2
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• pp.171-179
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• 2023

Due to man-made climate change, global abnormal weather phenomena have occurred, increasing disasters. Major developed countries(military) are preparing for disasters caused by extreme weather appearances. However, currently, disaster prevention plans and facilities have been implemented based on the frequency and intensity method based on statistical data, it is not enough to prepare for disasters caused by frequent extreme weather based on probability basis. The U.S. and British forces have been the fastest to take research and policy approaches related to climate change and the threat of disaster change, and are considering both climate change mitigation and adaptation. The South Korean military regards the perception of disasters to be storm and flood damage, and there is a lack of discussion on extreme weather and disasters due to climate change. In this study, the process of establishing disaster management systems in developed countries(the United States and the United Kingdom) was examined, and the response policies of each country(military) were analyzed using literature analysis techniques. In order to maintain tight security, our military should establish a response policy focusing on sustainability and resilience, and the following three policy approaches are needed. First, it is necessary to analyze the future operational environment of the Korean Peninsula in preparation for the environment that will change due to climate change. Second, it is necessary to discuss climate change 'adaptation policy' for sustainability. Third, it is necessary to prepare for future disasters that may occur due to climate change.

• Korean Journal of Construction Engineering and Management
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• v.24 no.6
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• pp.45-52
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• 2023

Recently, as climate change caused by greenhouse gases is intensifying, the international community has committed to reduce greenhouse gas emissions. The purpose of this study is to present the methodology and major considerations for investment judgment. Two actual cases of overseas projects were selected as study subjects. As an analysis method, the major risk factors were defined as a probability distribution, and the NPV was stochastically estimated using the Monte Carlo simulation method. In addition, assuming a policy change, the range of NPV change was analyzed. As a result, the average NPV of project A was lowered by 19%, and the probability of showing a negative NPV was 12.2%. The average value of project B was lowered by 12.5%. Considering the policy change, project A can obtain economic benefits only when it obtains 72.9% or more of the total amount of carbon credits generated, and project B is economically feasible when it acquires 49.5% or more. As a result, the average value of project A is lower than the net present value under basic assumptions, so caution is needed in investment decisions depending on changes in major risk factors. Additionally, considering policy changes, the carbon credit distribution ratio should be differentially applied depending on the project size, and this was presented as a specific figure.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.37 no.3
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• pp.163-171
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• 2024

Structural health monitoring for ships and offshore structures is important in various aspects. Ships and offshore structures are continuously exposed to various environmental conditions, such as waves, wind, and currents. In the event of an accident, immense economic losses, environmental pollution, and safety problems can occur, so it is necessary to detect structural damage or defects early. In this study, structural response data of multi-linked floating offshore structures under various wave load conditions was calculated by performing fluid-structure coupled analysis. Furthermore, the order reduction method with distortion base mode was applied to the structures for predicting the structural response by using the results of numerical analysis. The distortion base mode order reduction method can predict the structural response of a desired area with high accuracy, but prediction performance is affected by sensor arrangement. Optimization based on a genetic algorithm was performed to search for optimal sensor arrangement and improve the prediction performance of the distortion base mode-based reduced-order model. Consequently, a sensor arrangement that predicted the structural response with an error of about 84.0% less than the initial sensor arrangement was derived based on the root mean squared error, which is a prediction performance evaluation index. The computational cost was reduced by about 8 times compared to evaluating the prediction performance of reduced-order models for a total of 43,758 sensor arrangement combinations. and the expected performance was overturned to approximately 84.0% based on sensor placement, including the largest square root error.

• Journal of the Korean Applied Science and Technology
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• v.40 no.6
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• pp.1521-1532
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• 2023

This study was done to identify the face-to-face and non-face-to-face student counseling experiences of nursing students during the COVID-19 period. Data were collected through interviews with 10 students at S Women's University in Gyeonggi-do from December 2022 to April 2023. All recorded data were analyzed using an inductive content analysis method. As a result of the study, two themes, four categories, and eight subcategories were found. Themes were 'factors promoting counseling' and 'Non-facilitating factors in counseling'. The first theme category was 'adaptation to new counseling methods' and 'pursuing convenience as the MZ generation', and the second theme category was 'resistance to counselling' and 'discrepancy from the desire for mutual relationships'. Through this study, it was helpful to understand that student counseling is essential for nursing students and what the most appropriate and useful counseling method is. Additionally, this study provided important evidence to lay the foundation for comparative research on face-to-face and non-face-to-face counseling among research participants according to gender and major. Further suggests research to develop a student counseling program for nursing students and confirm its effectiveness.

• Journal of Astronomy and Space Sciences
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• v.26 no.1
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• pp.89-98
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• 2009

In this study, the YLPODS (Yonsei Laser-ranging Precision Orbit Determination System) is developed for POD using SLR (Satellite Laser Ranging) NP (Normal Point) observations. The performance of YLPODS is tested using SLR NP observations of TOPEX/POSEIDON and CHAMP satellite. JPL's POE (Precision Orbit Ephemeris) is assumed to be true orbit, the measurement residual RMS (Root Mean Square) and the orbit accuracy (radial, along-track, cross-track) are investigated. The validation of POD using GPS (Global Positioning System) raw data is achieved by YLPODS performance and highly accurate SLR NP observations. YGPODS (Yonsei GPS-based Precision Orbit Determination System) is used for generating GPS based precise orbits for TOPEX/POSEIDON. The initial orbit for YLPODS is derived from the YGPODS results. To validate the YGPODS results the range residual of the first adjustment of YLPODS is investigated. The YLPODS results using SLR NP observations of TOPEX/POSEIDON and CHAMP satellite show that the range residual is less than 10 cm and the orbit accuracy is about 1 m level. The validation results of the YGPODS orbits using SLR NP observations of the TOPEX/POSEIDON satellite show that the range residual is less than 10 cm. This result predicts that the accuracy of this GPS based orbits is about 1m level and it is compared with JPL's POE. Thus this result presents that the YLPODS can be used for POD validation using SLR NP observations such as STSAT-2 and KOMPSAT-5.

• The Journal of the Acoustical Society of Korea
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• v.43 no.1
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• pp.9-18
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• 2024

The importance of active sonar systems is emerging due to the quietness of underwater targets and the increase in ambient noise due to the increase in maritime traffic. However, the low signal-to-noise ratio of the echo signal due to multipath propagation of the signal, various clutter, ambient noise and reverberation makes it difficult to identify underwater targets using active sonar. Attempts have been made to apply data-based methods such as machine learning or deep learning to improve the performance of underwater target recognition systems, but it is difficult to collect enough data for training due to the nature of sonar datasets. Methods based on mathematical modeling have been mainly used to compensate for insufficient active sonar data. However, methodologies based on mathematical modeling have limitations in accurately simulating complex underwater phenomena. Therefore, in this paper, we propose a sonar signal synthesis method based on a deep neural network. In order to apply the neural network model to the field of sonar signal synthesis, the proposed method appropriately corrects the attention-based encoder and decoder to the sonar signal, which is the main module of the Tacotron model mainly used in the field of speech synthesis. It is possible to synthesize a signal more similar to the actual signal by training the proposed model using the dataset collected by arranging a simulated target in an actual marine environment. In order to verify the performance of the proposed method, Perceptual evaluation of audio quality test was conducted and within score difference -2.3 was shown compared to actual signal in a total of four different environments. These results prove that the active sonar signal generated by the proposed method approximates the actual signal.

• KIPS Transactions on Software and Data Engineering
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• v.12 no.1
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• pp.19-30
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• 2023

An electric scooter(e-scooter), one popularized micro-mobility vehicle has shown rapidly increasing use in many cities. In South Korea, the use of e-scooters has greatly increased, as some companies have launched e-scooter sharing services in a few large cities, starting with Seoul in 2018. However, the use of e-scooters is still controversial because of issues such as parking and safety. Since the perception toward the means of transportation affects the mode choice, it is necessary to track the trends for electric scooters to make the use of e-scooters more active. Hence, this study aimed to analyze the trends related to e-scooters. For this purpose, we analyzed news articles related to e-scooters published from 2014 to 2020 using dynamic topic modeling to extract issues and sentiment analysis to investigate how the degree of positive and negative opinions in news articles had changed. As a result of topic modeling, it was possible to extract three different topics related to micro-mobility technologies, shared e-scooter services, and regulations for micro-mobility, and the proportion of the topic for regulations for micro-mobility increased as shared e-scooter services increased in recent years. In addition, the top positive words included quick, enjoyable, and easy, whereas the top negative words included threat, complaint, and ilegal, which implies that people satisfied with the convenience of e-scooter or e-scooter sharing services, but safety and parking issues should be addressed for micro-mobility services to become more active. In conclusion, this study was able to understand how issues and social trends related to e-scooters have changed, and to determine the issues that need to be addressed. Moreover, it is expected that the research framework using dynamic topic modeling and sentiment analysis will be helpful in determining social trends on various areas.