• Journal of the Computational Structural Engineering Institute of Korea
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• v.31 no.6
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• pp.347-352
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• 2018

This study proposes seismic response analysis technique of a two-mass rack system which sustains heavy loads with frictional behavioral characteristics. In order to deal with the nonlinear frictional characteristics of the mass on the rack system, the equations of motion of the system has been derived and the appropriate numerical simulation technique has been developed. In order to examine the seismic performance of the proposed system, we consider two parameters that are expected to have great influence on the seismic performance of the system. One is the ratio of the two masses of the load and the rack structure, and the other is the friction coefficient between rack and loaded mass. A number of numerical simulations of the seismic response of structures with various natural frequencies for both parameters have been performed in order to investigate the seismic safety of the rack structures. From the simulated results. it is observed that the maximum displacement of the rack system tends to decrease drastically as the natural frequency of the structure increases regardless of the two parameters of mass ratio and friction coefficient. The proposed study provides important reference data to guarantee the seismic safety of the rack system by considering nonlinear frictional behavior of the loaded mass.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.5
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• pp.73-80
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• 2019

In this paper, the basic design of the electric hydraulic sliding deck system was developed to develop the electric hydraulic sliding deck which can easily upgrade the loading and unloading of the agricultural machinery by modifying the load of the existing 5ton cargo truck. Through the kinematic analysis, The length and structure of the specimens were designed and the materials were selected for safety and economical efficiency through structural analysis. For the basic design of the sliding deck system, we surveyed the agricultural machinery to be transported and selected necessary elements. And have devised a system using a hydraulic cylinder that can meet selected factors. Through the simplified modeling and kinematic diagram, the operating structure of the sliding deck system was grasped and the minimum length and structure of the sliding deck were devised, In order to select the sliding deck material satisfying, four representative materials used in the automobile structure were selected. Selected the parts to be analyzed and compared the stresses and deformation amounts according to the material under the conditions of maximum load through simplified modeling. As a result, SS41P material was used to reduce the unit cost and to achieve safety. The winch system was designed and applied for moving up and down of the farm machinery which can not be operated.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.2
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• pp.401-408
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• 2021

Supplies of wood chips for fuel tend to increase owing to energy decentralization and new renewable energy policies. This study suggests a technical method that is necessary in order to supply heating energy to rural regions by using wood chips for fuel. Therefore, this study investigates the effects of natural drying methods for eight months by installing a drying facility with natural ventilation capable of loading 10 tons of wood chips, and which derive a natural drying method based on this to meet the quality standards of wood chips for fuel. The study results confirm that it is possible to produce wood chips for high-quality fuel with water content at 20% or less after around 90 days of drying, provided that a drying facility with natural ventilation is equipped with materials that can be procured easily in rural regions. It is also possible to block the proliferation and fermentation of molds that affect the quality of wood chips, provided that intake and exhaust systems adhering to standards are equipped.

• Journal of Korea Entertainment Industry Association
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• v.14 no.6
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• pp.91-107
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• 2020

The purpose of this study is to explore quantitatively the success factors of YouTube's music cover channel. Along the process, constructing and testing the measurement for music cover channel's characteristics. The research constructed the measurement items based on results of qualitative studies. To perform the purposes the study suggest a research model which integrated the Post Acceptance Model with five music cover channel's characteristics based on the recent case studies. The five characteristics were contents, video, creator, interactivity, and publicity. The characteristics were integrated with Post Acceptance Model. After testing reliability and validity the research model was revised then, the research hypothesis was tested. The research results show: first, it was found that the content characteristics did not meet the expected value of users. Second, among the five factors of channel characteristics presented in creator's characteristics have the largest effect on user's value perception Third, in the factor analysis process, the content factor and the video were loaded on the same factor thus integrated as one factor. Fourth, satisfaction and intention for continual usage were also loaded on the same factor thus integrated as one factor. The research results suggest that music cover channel operators need to enhance the creator's attraction, communication with user, and publicity in various ways.

• Journal of Korean Elementary Science Education
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• v.41 no.1
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• pp.65-78
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• 2022

This study aims to 1) verify the validity of the Science self-efficacy scale and 2) perform a latent mean analysis of the background variables about a pre-service teacher. The study uses pre-tests to analyze data from 187 pre-service teachers, which uses Tark's Science self-efficacy scale (2011). To identify the factor structure, exploratory factor analysis was performed. Based on the results of the pilot test, the expert group council revised the scale for the pre-service teachers to respond to the 3-factor structure. In the main test, 354 data were analyzed through a modified Science self-efficacy scale, and exploratory and confirmatory factor analyses were performed. The results of the study are as follows: First, in the pilot test, the pre-service teacher responded to a 3-factor instrument, but the validity of two items was examined further below. Second, the pre-service teachers responded to a 3-factor instrument on 29 items for the modified Science self-efficacy scale. The total reliability of the instrument was .886 and the reliability of each factor was analyzed as .882-.886. Finally, the latent mean analysis by gender showed that females have a higher self-regulation efficacy factor and males have a higher self-confidence factor (Cohen's d > .3). Furthermore, there is a significant difference in task difficulty preference and self-regulatory efficacy factor (Cohen's d > .8) between the college preparatory and science subject preference. This study provides important insights into and contributions to the accurate scientific self-efficacy diagnosis of pre-service teachers, as well as proposes a curriculum to improve the scientific self-efficacy of prospective teachers.

• Journal of the Korea Institute of Building Construction
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• v.22 no.6
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• pp.681-688
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• 2022

In this study, the process of drone photography, automatic volume calculation, total floor area conversion, and waste calculation was constructed as a QGIS plug-in to predict the demolition waste (DW) generated in an aged area where drawing information or building information is uncertain. Through a case study, the high consistency between the automatically calculated volume using the drone and the BIM volume based on the field measurement was confirmed. Field application was carried out for the planned demolition work site, and the consistency between the drone-based volume and the actual measurement-BIM-based volume was reconfirmed. The waste generation unit was applied and the amount of DW was calculated by setting the floor height and building type, and the entire process was completed within 6 hours. Although the difference between building information and building objects through drones occurred according to the setting of temporary structures, loads, and floor heights, it was found that the actual amount of DW was generated more than the initial estimate. It is expected that measures to improve the accuracy of volume and floor area conversion will be required through case studies in the future.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.6
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• pp.946-954
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• 2022

More than half of barges have been surveyed and designated as an "unmanned barge". The main advantage of the unmanned barge is that it can carry more cargo equivalent to 25 percent of freeboard compared to that of a manned barge. In contrast, it needs an onboard crew barge because the bargeman is in charge of several tasks during sailing such as mooring or unmooring barges to or from a wharf, dropping and heaving up an anchor and turning on and of navigational lights and shapes. The instant recognition is that a tug assume the responsibility of operating a barge; however, different situations exist in which the shipper, as the operator of the barge, hires a tug. Although a tug might be a carrier of a barge under a specific contract, the master of the tug should fulfill his duty to complete its voyage. Most masters are not provided with the particulars of a barge and the information regarding the bargemen onboard, which is believed not to respect the master's authority and lead to an unintended violation of relevant laws. This paper presents three recommendations for resolving these issues: the policy approach for changing unmanned barges to manned barges, issuing a minimum safe manning certificate, and providing the master of tug information on the barge and the crew onboard. Thus, the proposed approach can be expected to improve the crew's working conditions, diminish the violation of the maximum number of persons onboard the barge, and ensure the authority of the master of tug through such recommendations.

• The Journal of the Convergence on Culture Technology
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• v.8 no.5
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• pp.409-421
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• 2022

The purpose of this study is to understand the flow of personnel management in the Joseon Dynasty through Dasan Jeong Yak-yong's Mokminsimseo, and to understand how it is being used not only in modern administrative organizations but also in social welfare organizations. As a result, first, first, among the human resource management areas of the Joseon Dynasty, the area occupied the most was related to integrity. These are the contents that are widely used in evaluation methods and scope, value standards, and use of evaluation today. Second, regarding the recruitment and recruitment of talents in the Joseon Dynasty, various methods were presented to enhance the appropriateness, fairness of hiring, and the effectiveness of hiring human resources. This has significant implications even today as it specifically mentions the appropriate appointment and scale of human resources, emphasizing that personnel is everything. Finally, This is different from the human resource management of the Joseon Dynasty in that it is being converted to a compensation paradigm rather than discipline as a way to inspire the motivation of workers today and increase work efficiency. In addition, professionalism was emphasized in the education and training of public officials, and the maintenance of dignity and leadership in body and mind is emphasized, showing that even today, the virtues required of workers in public organizations, including social welfare organizations, are being maintained.

• Journal of Internet of Things and Convergence
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• v.9 no.1
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• pp.71-76
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• 2023

Recently, in order to store and manage big data, research and development of a high-performance storage system capable of stably accessing large data have been actively conducted. In particular, storage systems in data centers and enterprise environments use large amounts of SSD (solid state disk) to manage large amounts of data. In general, SSD uses FTL(flash transfer layer) to hide the characteristics of NAND flash memory, which is a medium, and to efficiently manage data. However, FTL's algorithm has a limitation in using DRAM more to manage the location information of NAND where data is stored as the capacity of SSD increases. Therefore, this paper introduces FTL policies that apply virtual memory to reduce DRAM resources used in FTL. The virtual memory-based FTL policy proposed in this paper manages the map data by using LRU (least recently used) policy to load the mapping information of the recently used data into the DRAM space and store the previously used information in NAND. Finally, through experiments, performance and resource usage consumed during data write processing of virtual memory-based FTL and general FTL are measured and analyzed.

• Journal of the Korean Association of Geographic Information Studies
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• v.26 no.3
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• pp.12-36
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• 2023

Graph databases, which store different types of data and their relationships modeled as a graph, can be effective in managing and analyzing real estate spatial data linked by complex relationships. However, they are not widely used due to the limited spatial functionalities of graph databases. In this study, we propose a uniform grid-based real estate spatial data management approach using a graph database to respond to various real estate-related spatial questions. By analyzing the real estate community to identify relevant data and utilizing national point numbers as unit grids, we construct a graph schema that linking diverse real estate data, and create a test database. After building a test database, we tested basic topological relationships and spatial functions using the Jackpine benchmark, and further conducted query tests based on various scenarios to verify the appropriateness of the proposed method. The results show that the proposed method successfully executed 25 out of 29 spatial topological relationships and spatial functions, and achieved about 97% accuracy for the 25 functions and 15 scenarios. The significance of this study lies in proposing an efficient data integration method that can respond to real estate-related spatial questions, considering the limited spatial operation capabilities of graph databases. However, there are limitations such as the creation of incorrect spatial topological relationships due to the use of grid-based indexes and inefficiency of queries due to list comparisons, which need to be improved in follow-up studies.