• Journal of Space Technology and Applications
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• v.1 no.3
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• pp.319-336
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• 2021

This paper discusses the results of launch environment tests for the engineering qualification model (EQM) of nanosatellite Scale magNetospheric and Ionospheric Plasma Experiment (SNIPE) for scientific missions and lessons learned for the design of nanosatellites. SNIPE is a group of four formation-flying 6U nanosatellites with a range of payloads for missions including space weather measurement. We developed the EQM to verify the preliminary design prior to fabricating the flight model. Launch environment test of EQM was conducted for the first time in 2019, and all failures were corrected and verified at the second test conducted in 2021. A notable point of the two tests is that the nanosatellite deployer used in the first test is different from that of the second test. The second deployer has the capability to fix the internal satellite whereas the first deployer just contains and deploys the satellite. Thus actual mechanical loads the satellite receives is reduced for the second test compared to the first test. This work compares the mechanical responses of two tests and proposes general guidelines for structural design of nanosatellites.

• Korean Association of Arts Management
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• no.54
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• pp.59-93
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• 2020

The development of digital technology has made consumers more knowledgeable about products than ever before. In this regard, experts have defined consumers in the digital age as knowledge seekers and pointed out that they are proficient in acquiring and sharing product knowledge prior to purchase. For service goods such as musicals, product prior knowledge executes strong effect due to such characteristics as intangibility, inseparabilit y,and heterogeneity. Prior studies in the field of performing arts, including musicals, have revealed that the prior knowledge of the audience has a positive effect on the satisfaction of the audience and WOM(word-of-mouth) intention. However, studies in the marketing field argue that consumers' high prior knowledge may have a negative impact on customer satisfaction and product evaluation depending on conditions, as they are more likely to compare, review, and expect products more closely. Therefore, in this study, we tried to identify under what conditions the musical prior knowledge enhances audience satisfaction and WOM intention. According to the results of previous studies, a mediating effect model was established in which the musical prior knowledge enhances the WOM intention through the mediation of the audience satisfaction. Then, Transportation was introduced as a mediation variable and it was verified whether the level changed the audience satisfaction and WOM intention. The reason for the introduction of the transportation construct reflects the results of previous research that the story is important component of musical. The results showed that the musical prior knowledge has a significant effect on WOM intention through the mediation of audience satisfaction. The moderating effect of transport was also significant on the relationship between musical prior knowledge and audience satisfaction. Lastly, through moderated-mediation analysis, it was confirmed that transportation moderates the mediating effect that prior knowledge affects on the WOM intention through audience satisfaction. Based on the results, we demonstrated that a musical story is fairly important to satisfy audiences with high prior knowledge. This study could contribute to the related filed in that it introduced the transportation construct for the first time, thereby broadening the understanding of the musical audiences in the era of smart consumers.

• The Journal of Engineering Geology
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• v.32 no.4
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• pp.597-610
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• 2022

Knowledge of the failure behavior of friction materials considering their intermediate principal stress is related to an understanding of situations where these materials might be used: for example, the stability of deep-seated boreholes and fault slip analysis. This study designed equipment for physically implementing true triaxial compression and used it to assess specimens of plaster, a friction material. The material's mechanical behaviors are discussed based on the results. The applicability of the 3D failure criteria are also reviewed. The tested specimens were molded cuboids of width, length, and height 52, 52, and 104 mm, respectively. A total of 24 true triaxial compression tests were performed under various combinations of 𝜎₃ and 𝜎₂ conditions. Conventional uniaxial and triaxial compression tests were employed to estimate the mechanical properties of the plaster for use as parameters for 3D failure criteria. Examining the stress-strain relations of the plaster materials showed that a large difference between the intermediate principal stress and the minimum principal stress indicated strong brittle behavior. The mechanical behavior of the plaster used here reflects the change of intermediate principal stress. Nonlinear multiple regression analysis on the test data in the principal space showed that the modified Wiebols-Cook failure criterion and the modified Lade failure criterion were the most suitable 3D failure criteria for the tested plaster.

• Journal of the korean academy of Pediatric Dentistry
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• v.48 no.4
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• pp.384-396
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• 2021

The 61^st Korean Academy of Pediatric Dentistry congress was hosted online for the first time in 2020 due to coronavirus disease-19. The congress was operated using the ZOOM platform. The aim of this paper is to analyze and evaluate the overall satisfaction and feedbacks from congress participants via anonymous Google Forms online survey. A test meeting was previously organized before the actual congress to facilitate the smooth process and the participants overall showed high satisfaction. Members who participated in test meeting compared to those who did not, found it significantly helpful, which contributed overall higher satisfaction with the online congress. Abstracts were accepted from the current pediatric dentistry residents and the oral presentations were also held online for the first time. The presenters and the judges were overall very satisfied. In an unguaranteed situation of termination of coronavirus disease-19, the decision to conduct an online congress was a favorable option.

• Journal of Korea Society of Industrial Information Systems
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• v.27 no.4
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• pp.19-27
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• 2022

In general, the performance of ML(Machine Learning) application is determined by various factors such as the type of ML model, the size of model (number of parameters), hyperparameters setting during the training, and training data. In particular, the recognition accuracy of ML may be deteriorated or experienced overfitting problem if the amount of dada used for training is insufficient. Existing studies focusing on image recognition have widely used open datasets for training and evaluating the proposed ML models. However, for specific applications where the sensor used, the target of recognition, and the recognition situation are different, it is necessary to build the dataset manually. In this case, the performance of ML largely depends on the quantity and quality of the data. In this paper, training data used for motion recognition application is augmented using the kernel density estimation algorithm which is a type of non-parametric estimation method. We then compare and analyze the recognition accuracy of a ML application by varying the number of original data, kernel types and augmentation rate used for data augmentation. Finally experimental results show that the recognition accuracy is improved by up to 14.31% when using the narrow bandwidth Tophat kernel.

• Journal of Korean Elementary Science Education
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• v.41 no.1
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• pp.118-133
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• 2022

In this study, we analyze the strengths and limitations of student convergence education and teacher-training programs offered by a science education institute in the capital region and provide suggestions for organizing and running similar programs in other science education institutes and schools. Reviews of relevant literature and interviews with internal and external expert groups were conducted, and an analytic framework was developed. Based on the framework, we collected data using focus group interviews and email communications with experts. The data were analyzed using both qualitative and quantitative methods within two areas, namely, convergence education programs for students and teacher-training programs. The data analysis results revealed the status of student convergence education and teacher-training programs in the institute. Furthermore, we also provided suggestions for improving programs in other informal science education institutes and schools through the interaction between the two areas in the framework and educational and social needs.

• Journal of Korean Library and Information Science Society
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• v.53 no.3
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• pp.95-117
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• 2022

This study was conducted as basic research for establishing a mid to long term development plan for libraries in Uiseong-gun, designated as a depopulated area. First, the social, cultural, and environmental characteristics of Uiseong-gun were analyzed and compared with the library infrastructure of depopulation areas similar in size with Uiseong-gun. In addition, a survey was conducted on the perception of users to understand the usage status of libraries, satisfaction with services and improvement plans, non-use factors, and demands for new libraries. Based on this process, the direction of Uiseong-gun library policy was presented. Specifically, four strategic directions for the development of libraries (future orientation, community revitalization, service specialization of the information poor, enhancement of local humanities and spiritual culture) and five key service tasks (building library brand, implementing innovative spaces and services, expanding library functions for improvement of settlement conditions of residents, developing and providing services for the elderly reflecting local characteristics, promoting reading culture) were derived. The proposed core tasks focused on future-oriented library services to overcome the limitations of a population decrease area and develop the potential of Uiseong-gun.

• Journal of Industrial Convergence
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• v.21 no.1
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• pp.111-122
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• 2023

The purpose of this study is to verify the factors affecting survival time by estimating survival rate and survival time using non-financial information of social enterprises using credit guarantee in credit guarantee institutions, and provide information to stakeholders to improve survival rate and employ to contribute to maintaining and expanding the As a research method, survival analysis was performed using a non-parametric analysis method, Kaplan-Meier Analysis. As a sample, 621 companies (577 normal companies, 44 insolvent companies) established between 2009 and 2018 were selected as the target companies. As a result of examining the factors affecting survival time by classifying social enterprise representative information and corporate information, representative credit rating, representative home ownership, credit transaction period, and corporate credit rating were derived as significant variables affecting survival time. In the future, financial institutions will be able to induce corporate soundness by reflecting factors that affect survival when examining loans for social enterprises, contributing to job retention and reduction of social costs. Supporting organizations such as the government and private organizations will be able to use it in various ways, such as policy establishment and education and training for the growth and sustainability of social enterprises. With this study as an opportunity, I hope that research will continue with more interest in the factors influencing social enterprise performance as well as corporate insolvency.

• Korean Journal of Ecology and Environment
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• v.55 no.2
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• pp.156-166
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• 2022

Understanding the characteristics of reservoir water quality is fundamental in reservoir ecosystem management. The water quality of reservoirs is affected by various factors including hydro-morphology of reservoirs, land use/cover, and human activities in their catchments. In this study, we classified 83 major reservoirs in South Korea based on nine physicochemical factors (pH, dissolved oxygen, chemical oxygen demand, total suspended solid, total nitrogen, total phosphorus, total organic carbon, electric conductivity, and chlorophyll-a) measured for five years (2015~2019). Study reservoirs were classified into five main clusters through hierarchical cluster analysis. Each cluster reflected differences in the water quality of reservoirs as well as hydromorphological variables such as elevation, catchment area, full water level, and full storage. In particular, water quality condition was low at a low elevation with large reservoirs representing cluster I. In the comparison of eutrophication status in major reservoirs in South Korea using the Korean trophic state index, in some reservoirs including cluster IV composed of lagoons, the eutrophication was improved compared to 2004~2008. However, eutrophication status has been more impaired in most agricultural reservoirs in clusters I, III, and V than past. Therefore, more attention is needed to improve the water quality of these reservoirs.

• Korean Journal of Ecology and Environment
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• v.55 no.3
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• pp.212-220
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• 2022

An estuary is a water ecosystem with a high abundance of the species diversity, due to a variety of complex physicochemical factors of the area where freshwater and ocean mixed. The identification of Corbicula species in the estuary environments is difficult because of various morphological characteristics. In this study, we provide taxonomic information on Corbicula species with taxonomic difficulties using morphological and genetic analysis. This study was conducted on clams from the Seomjin River-Gwangyang Bay, one of the major production area of marsh clam in Korea. As a result, we characterized Cytocrome C Oxidase subunit I (COI) sequences of the Corbicula. The 636 bp nucleotide sequences of COI have 98% homology among Corbicula species collected from 2 sites of Seomjin River-Gwangyang Bay. The phylogenetic analysis with 17 species of Corbicula indicated that most of the species collected from Seomjin River-Gwangyang Bay were brackish water clam (Corbicula japonica), and only one Asian clam (Corbicula fluminea). The evolutionary distance between C. japonica and C. fluminea was less than 0.003. Therefore, it was confirmed that C. japonica is phylogenetically closely related to C. fluminea. In 9 species of Cyrenidae, phylogenetic tree was classified into three lineages. These results will be used as an important data for an identification of clam species by providing genetic information for Corbicula species with a morphological diversity.