• Journal of the Korea Convergence Society
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• v.10 no.4
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• pp.153-163
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• 2019

The importance and necessity of convergence research to solve complexity and diversity of research problems is more increasing. For successful convergence research, connectivity beyond the boundary and distance between disciplines is a key factor. To understand the current status and characteristics of connectivity among researchers, we investigated the interdisciplinary relationships among 487 researchers' disciplines in a university by using network anaylsis. The results showed that (1) connectivity between similar disciplines were higher than different disciplines, (2) the density and cohesion level of connectivity within the same campuses were higher, and (3) network centrality was concentrated in engineering and medicine. Based on these results, the necessity of overcoming boundaries and distances as obstacles to convergence research and the necessity of diversification of centrality were proposed. While previous studies mainly analyzed the research outcomes, this study is meaningful because it analyzed researchers' connectivity and collaborative structures in the actual convergence research procedures.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.2
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• pp.243-253
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• 2019

First steps of Planetary exploration are usually conducted with the use of autonomous rovers. These rovers are capable of finding its own path and perform experiments about the planet's surface. This paper makes a proposal for a multi-agent system which effectively take the advantage of a blackboard system for share knowledge and effort of each agent. Agents use Reactive Model with the combination of Belief Desire Intension (BDI) Model and also use a Path Finding Algorithm for calculate shortest distance and a path for travel on the planet's surface. This approach can perform a surface exploration on a given terrain within a short period of time. Information which are gathered on the blackboard are used to make an output with detailed surface soil variance results. The developed Multi-Agent system performed well with different terrain sizes.

• Design & Manufacturing
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• v.15 no.3
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• pp.56-61
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• 2021

The increase in automation facilities in the injection molding industry is a very important process control item. The most important item when constructing an unmanned machine using a take-out robot is the "mold opening stroke" of the mold. The injection molding machine control method is divided into hydraulic type and electric type, and there have been few studies on the mold opening distance according to the control method. In this study, the correlation was confirmed by increasing the injection speed to 20, 50, 80, and 100% for the three types of hydraulic control method, open loop and close loop, and electric control method. Through the experiment, the following results were obtained. (1) It can be seen that the reproducibility is excellent with the electric, close loop, and open loop control methods. (2) When the injection speed is set to 50%, the mold opening distance is 263.10~263.27 mm, which is the most reproducible. (3) As a result of ANOVA, both injection speed and mold opening distance showed a significant difference in the hydraulic control method (p<0.05), but it was verified through experiments that there was no significant difference in the electric control method. Based on these results, when electric control is selected rather than hydraulic control, the reproducibility of the mold opening distance is excellent, so it is thought that the taking-out robot can take the object out of the mold more safely.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.5
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• pp.195-203
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• 2019

In this article, it was studied how positive psychological capital in the service industry workers affected the service performances by perfectionism and role conflict in the service industry employees. This was to suggest the practical solutions on the emotional labor or job stress that the existing workers in the service industry were experiencing. Upon the study results, self-efficacy, hope, and resilience among the factors of positive psychological capital showed to affect perfectionism and role conflict while optimism did not. Based on this study, the practices and problems of the workers in the service industry could be understood and it seems to improve and support their working environment to provide better services. In other words, these results mean to enhance the self-efficacy and resilience of the workers in the service industry so as to provide the stakeholders of service industry or related institutions with the basic data.

• Applied Chemistry for Engineering
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• v.31 no.6
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• pp.668-673
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• 2020

In this work, ultrathin and two-dimensional (2D) cobalt hydroxide [Co(OH)2] nanosheets were synthesized by a sonication assisted liquid-phase exfoliation of bulk Co(OH)2. The resulting exfoliated Co(OH)2 is a hexagonal mono-layered nanosheet with a high specific surface area of 27.5 ㎡ g-1. The depolymerization of polyethylene terephthalate (PET) based on glycolysis reaction was also performed using an exfoliated Co(OH)2 catalyst. Excellent catalytic reaction performances were demonstrated; a high PET conversion and bis(2-hydroxyethyl) terephthalate (BHET) yield of both 100% using the nanosheet catalyst were achieved within a reaction time and temperature of 30 min and 200 ℃, respectively. The long-term stability of exfoliated Co(OH)2 catalysts was also demonstrated by recyclability tests of the catalyzed glycolysis reaction of PET over four cycles, showing both 100% of high PET conversion and BHET yield.

• Journal of Internet of Things and Convergence
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• v.8 no.2
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• pp.7-12
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• 2022

The main cause of cable accidents is the accelerated deterioration of the cable itself or internal and external electrical, mechanical, chemical, thermal, moisture intrusion, etc., which reduces insulation performance and causes insulation breakdown, leading to cable accidents. Insulation deterioration can occur even when there is no change in the appearance of the cable, so there is a difficulty in preventing cable accidents due to insulation deterioration. Since cable accidents can occur in areas with poor insulation due to the effects of overvoltage and overcurrent, it is necessary to comprehensively analyze transformers and circuit breakers, and ground faults caused by phase-to-phase imbalance. Ground fault accidents due to insulation breakdown of cables can occur due to defects in the cable itself and poor cable construction, as well as operational influences, arcs during operation of electrical equipment (switchers, circuit breakers, etc.). analysis is needed. This study intends to examine the causes of cable accidents through analysis of cable accidents that occurred in a manufacturing factory.

• Industry Promotion Research
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• v.7 no.4
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• pp.9-15
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• 2022

This study evaluated the automated system of the roll bending process, which is one of the difficult processes. In the past, 20 cartridges were produced per hour. but Automation changed it to a process that produces 50 pieces per hour. The average value of production was 57.6 pieces per hour, error of repeatability was 0.03 mm, average roll diameter error value was 0.49 mm, average alignment error value was 0.09 mm and average process lead time was 43.21 seconds. This paper presented specific evaluation methods such as productivity, repeatability, defect rate, alignment defect rate, and process lead time. It is thought that the contents performed in this study will be helpful in the verification of other automation systems in the future.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.5
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• pp.791-797
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• 2022

Using the fatigue limit (△σ_unsm) and residual stress (σ_r) of the UNSM smooth specimen, the harmless maximum crack depth (α_hml) according to the crack aspect ratio (As) was evaluated. α_hml evaluated the reliability in the relationship between the minimum crack depth (α_NDI1, α_NDI2) detectable by nondestructive inspection(NDI) and the crack depth (α₂₅, α₅₀) that reduces the fatigue limit by 25% and 50%. All α_hml was determined by the crack depth. The α_hml of 80N UNSM with high σ_r and high △σ_unsm was found to be large. σ_r in the depth direction had a much effect on α_hml. Since α_hml>α₅₀(As=0.6-0.1) and α_hml>α₂₅, α₂₅ and α₅₀(some range) can secure the safety and reliability. Since α_hml<α₅₀ (As=1. 0-0. 6), it cannot be made harmless by UNSM. So safety and reliability cannot be secured. α_NDI1 and α_NDI2 are larger than α₂₅, α₂₅ cannot be detected by NDI. α_NDI1 and α_NDI2 are smaller than α₅₀, α₂₅ can detected by NDI.

• Journal of the Korean Society of School Health
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• v.35 no.3
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• pp.143-151
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• 2022

Purpose: The purpose of this study was to examine the effects of being aware of the physical and psychosocial environment of the school on subjective feeling of happiness in Korean middle and high school students. Methods: The data of "Health and lifestyle Survey (2019)" conducted by the National Youth Policy Institute were analyzed after receiving approval though the website. A total of 5,311 middle and high school students were included in the analysis. Descriptive statistics, t-test, one-way ANOVA, pearson correlation, and multiple regression analysis were executed using SAS 9.4. Results: The mean score of subjective feeling of happiness was 6.92±0.56 out of 10. From the univariate analysis, the more positive the perception of the physical school environment was, such as classrooms, restrooms, exercise facilities, catering facilities, health facilities, other school facilities and school uniform, the higher the subjective feeling of happiness was (p for all <.001). In addition, the psychosocial environment of the school was significantly related to the happiness of adolescents (p<.001). After controlling for gender, school level, school grade, socio-economic status, and stress, positive perception of classrooms (B=0.04, p<.001), catering facilities (B=0.01, p=.021), health facilities (B=0.08, p<.001), and the psychosocial environment of the school (B=0.18, p<.001) was significantly associated with happiness of the students. Conclusion: Positive perception of the school environment was found to increase happiness in adolescents. Therefore, efforts should be made to make classrooms, catering facilities, and health facilities a pleasant space as well as to create a school atmosphere that values health.

• Transactions of the Korean hydrogen and new energy society
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• v.33 no.3
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• pp.219-225
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• 2022

In this study, as one part of the studies on the mechanical properties of the polymer electrolyte membrane, a study was conducted on the change in the mechanical properties due to hydration before and after aging of the polymer electrolyte membrane. The mechanical properties of the polymer electrolyte membrane changes due to hydration were confirmed through tensile tests of hydrated and non-hydrated Nafion 117. As results of this study, non-hydrated membrane showed higher mechanical properties than hydrated thing in the elastic region and some plastic regions. But, it was confirmed that hydrated membrane exhibited higher mechanical properties than non-hydrated thing in the large plastic region. Hydrated membrane has a lower glass transition temperature than non-hydrated thing due to the role of water as a plasticizer. In addition, the number of ion aggregates decreases, but the size increases, and the hydrated Nafion 117 is thought to have different mechanical properties from that of the non-hydrated thing due to the characteristic that the internal attraction is strengthened.