• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.4
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• pp.523-530
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• 2022

The problem in the construction of seawall reinforcing the seawall where there is seawater flow is the outflow of materials. Gravity-type pouring of concrete is difficult to fill the voids smoothly, and the cement of concrete that has not hardened is likely to be dispersed in seawater. This phenomenon not only reduces the reliability of quality after concrete hardening, but can also adversely affect the surrounding environment. Therefore, there is a need for a gel-like injection material that can be injected, In this study, the initial strength and durability improvement effect of seawater immersion were evaluated by using electrofurnace reduction slag and blast furnace slag with acute properties. As a result of the experiment, it was possible to prepare a gel-like injection material having flowability through reaction with silica-based chemical liquid. The flowability of the gel is 105~143 mm depending on the formulation, and the on-site simulation test can fill the voids without external leakage, confirming its on-site applicability.

• Journal of the Korean institute of surface engineering
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• v.34 no.5
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• pp.414-420
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• 2001

A 30-kV plasma immersion ion implantation setup (P $I^3$) has been equipped with a self-developed 6'-magnetron to perform hard coatings with enhanced adhesion by P $I^3$D(P $I^3$ assisted deposition) process. Using ICP source with immersed Ti antenna and reactive magnetron sputtering of Ti target in $N_2$/Ar ambient gas mixture, the TiN films were prepared on Si substrates at different pulse bias and ion-to-atom arrival ratio ( $J_{i}$ $J_{Me}$ ). Prior to TiN film formation the nitrogen implantation was performed followed by deposition of Ti buffer layer under A $r^{+}$ irradiation. Films grown at $J_{i}$ $J_{Me}$ =0.003 and $V_{pulse}$=-20kV showed columnar grain morphology and (200) preferred orientation while those prepared at $J_{i}$ $J_{Me}$ =0.08 and $V_{pulse}$=-5 kV had dense and eqiaxed structure with (111) and (220) main peaks. X-ray diffraction patterns revealed some amount of $Ti_{x}$ $N_{y}$ in the films. The maximum microhardness of $H_{v}$ =35 GN/ $M^2$ was at the pulse bias of -5 kV. The P $I^3$D technique was applied to enhance wear properties of commercial tools of HSS (SKH51) and WC-Co alloy (P30). The specimens were 25-kV PII nitrogen implanted to the dose 4.10$^{17}$ c $m^{-2}$ and then coated with 4-$\mu\textrm{m}$ TiN film on $Ti_{x}$ $N_{y}$ buffer layer. Wear resistance was compared by measuring weight loss under sliding test (6-mm $Al_2$ $O_3$ counter ball, 500-gf applied load). After 30000 cycles at 500 rpm the untreated P30 specimen lost 3.10$^{-4}$ g, and HSS specimens lost 9.10$^{-4}$ g after 40000 cycles while quite zero losses were demonstrated by TiN coated specimens.s.

• Composites Research
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• v.21 no.2
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• pp.8-14
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• 2008

Decrease of strength in composite material is generally caused by water absorption. It makes fracture of material, and loss of money or human lives. The objective of this study is to investigate the causes of decrease in strength by water absorption. Mechanism of water absorption was supposed as three steps. This mechanism is consisted of absorption into resin, absorption between resin and surface treatment agent, and delamination between fiber and resin. Conditions of test were supplied differently; kinds of fiber and resin, immersion time etc. Both of reversible reaction and irreversible reaction occurred simultaneously. Most of decrease in strength was finished at 2.5% water absorption, and the strength was recovered. At 4% water absorption, most of decrease was caused by irreversible reaction, therefore, there was a tendency not to be recovered in strength.

• Knowledge Management Research
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• v.24 no.1
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• pp.223-243
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• 2023

RPA is implemented through management policy and enforced in mandatory environments to enhance performance and efficiency in various fields. However, the success of RPA implementation depends on the level of active engagement from organization members, even in a mandatory setting. This study identifies perceived ease of use, usefulness, accountability, perceived risk, and self-efficacy as variables that influence conative use behavior, which consists of reflective secondary factors such as immersion, reinvention, and learning. Data was collected from 207 office workers in various industries who have experience with RPA to test the proposed research model. The structural equation was verified using SPSS 20.0 and SmartPLS 4.0, and the analysis showed that all the proposed variables had a significant impact on conative use behavior. Our research findings provide theoretical and practical implications in knowledge management, enabling companies that implement RPA to recognize and address factors that encourage their members to actively use RPA.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.6
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• pp.1-6
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• 2022

In this research, we suggest a real-time tele-driving system for unmanned fire truck control using the LTE communication system. The operator located in the safe area could drive the unmaned fire truck by implementing the secure tele-operation in case of the emergencies and disaster situation. A prototype of the unmaned fire truck was developed with a fire canon, a high pressure pump, a ball valve and a horse reel. The effect of time delay and FPS was quantified depending on the image sizes and the effective system for realtime tele-operation was suggested. To verify the suggested system, the test was performed between an operator and an unmanned fire truck which is approximately 30km apart. In this research, the immersion tele-driving system is suggested for real-time fire suppression with a 120ms time delay using LTE communication.

• Corrosion Science and Technology
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• v.22 no.3
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• pp.201-213
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• 2023

Corrosion management of an aircraft and its engine relies on rinsing and cleaning using tap water. Few studies have reported effects of tap water species on corrosion behaviors of structural materials. In this study, a series of experiments were conducted based on the design of experiment. Solutions with different levels of chloride and sulfate ions were prepared using a full factorial design. Two structural materials (aluminum alloy and steel) were used for an alternate immersion test. Weight loss was then measured. In addition, a silver specimen was utilized as a sensor for chloride deposition measurement. The silver specimen was examined using the electrochemical reduction method, XPS, and SEM-EDS. Surface analysis revealed that levels of chloride and sulfate ions were sufficient for the formation of silver chloride and silver surface. Statistical analysis of weight loss and chloride deposition rate showed significant differences in measured values. Concentration of chloride ions greatly affected corrosion behaviors of structural materials. Sulfate ion hindered the adsorption reaction. These results emphasize the importance of controlling ion concentration of tap water used for cleaning and rinsing an aircraft.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.06a
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• pp.214-217
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• 2022

In the maritime digital forensic part, it is very important and difficult process that analysis of data and information with vessel navigation system's binary log data for situation awareness of maritime accident. In recent years, analysis of vessel's navigation system's trajectory information is an essential element of maritime accident investigation. So, we made an experiment about corruption with various memory device in navigation system. The analysis of corruption test in seawater give us important information about the valid pulling time of sunken ship for acquirement useful trajectory information.

• The Journal of the Convergence on Culture Technology
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• v.9 no.5
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• pp.619-624
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• 2023

As the importance of digital competency education is highlighted, this study is a case study on block coding classes for elementary school students during vacation for the purpose of bridging the information education gap among students. The purpose of this study is to design and operate a play-centered block coding class program and find out if it is effective in improving students' interest. As a result of completing the teaching plan through the second consultation and revision, running the class, and analyzing the change in learning interest of the students through the t-test, the play-oriented block coding class designed in this study was effective in improving students' interest. In addition, it was possible to discover interesting elements such as student-led learning process and immersion through realistic play activities, friendship, collaboration, and communication through group activities. This study is significant in suggesting a plan to increase learning interest for students who are new to coding.

• Journal of Korean Elementary Science Education
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• v.43 no.1
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• pp.148-157
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• 2024

The purpose of this study was to develop an artificial intelligence-based marine ecological education program to improve the ecological sensitivity of elementary school students. The program was taught 11 times within 4 weeks, and an ecological sensitivity test was conducted before and after the program. The statistical results of the tests showed that the developed program improved the ecological sensitivity of elementary school students. Through in-depth interviews, improvements were found in all the areas, such as empathy for the living things, interest in nature, enjoyment of nature, and wonder about nature. Through the marine ecological classes, which used artificial intelligence and virtual reality, the students were able to get closer to nature, and the student participation activities showed a positive effect on their ecological sensitivity. This indicates that experience-oriented education methods are more effective than simple explanatory classes to improve the students' ecological sensitivity, and artificial intelligence technology proved effective in increasing the students' immersion in the class.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.24 no.2
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• pp.79-86
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• 2024

In this paper, we propose a virtual learning platform based on various interactions that occur during real class activities, rather than the existing content delivery-oriented learning metaverse platform. In this study, we provide a learning environment that combines AI and a virtual environment to solve problems by talking to real-time AI. Also, we applied G-learning techinques to improve class immersion. The Virtual Edu platform developed through this study provides an effective learning experience combining self-directed learning, simulation of interest through games, and PBL teaching method. And we propose a new educational method that improves student participation learning effectiveness. Experiment, we test performance on learninng activity based on real-time video classroom. As a result, it was found that the class progressing stably.