• Journal of Hydrogen and New Energy
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• v.33 no.6
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• pp.776-785
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• 2022

Hydrogen combustion in modern gas-turbine engine is the cutting edge technology as carbon-free energy conversion system. Flashback of hydrogen flame, however, is inevitable and critical specially for premixed hydrogen combustion. Therefore, this experimental investigation is conducted to understand flashback phenomenon in premixed hydrogen combustion. In order to investigate flashback characteristics in premixed hydrogen (H₂)/air flame, we focus on pressure conditions and nozzle shapes. In general, quenching distance reduces as pressure of combustion chamber increases, causing flashback from boundary layer near wall. The flashback regime for reference and modified candidate configurations can broadly appear with increasing combustion chamber pressure. The later one can improve flashback-resist by compensating flow velocity at wall. Also, improved wall flow velocity profile of suggested contraction nozzle prevents entire flashback but causes local flashback at nozzle exit.

• Journal of Soil and Groundwater Environment
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• v.28 no.1
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• pp.15-24
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• 2023

A persulfate(PS)/sulfidated microscale zero-valent iron(S-mZVI) system was tested for treating a soil contaminated with phenol. Sulfidation of bare mZVI was conducted using a mechanochemical process utilizing a ball mill in order to improve persulfate activation capacity and stability of unmodified mZVI. The synthesized S-mZVI performed markedly better than the bare mZVI in activating PS. The optimum molar ratio of sulfur to mZVI was around 0.12. In the soil slurry experiments, a very rapid and complete removal of phenol was observed at the optimum molar ratios of PS to S-mZVI of 2:1 and PS to phenol of 16:1. The phenol removal efficiencies decreased as the water content of the slurries decreased. This was believed to be due to increased soil oxidant demand as the amount of soil was increased as relative to the water content. To evaluate the field applicability of the process, slurry experiments adopting high soil contents were carried out that simulated in-situ soil mixing conditions. These experiments resulted in substantially compromised degradation efficiencies of 54.3% and 43.8% within 4 hours. The current study generally shows that the PS/S-mZVI process has a potential to be developed into a remediation technology for soils contaminated with organics.

• Fisheries and Aquatic Sciences
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• v.26 no.5
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• pp.355-365
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• 2023

The Pacific abalone, Haliotis discus hannai, is a highly valued and industrially important aquaculture species with growing demands of the expanding abalone aquaculture industry. To explore the feasibility of using the brown alga, Sargassum horneri, as a potential substitute for abalone feed, it is important to identify the feed preference and attractant effect of S. horneri on Pacific abalone. Our experiments indicated that the feeding-associated movement of abalone could be detected using a video tracking system under indirect illumination with dim red light. To further analyze the attraction potentials of various test materials, preference analysis was performed using Avicel-coated glass plates with ground powders of various seaweeds (e.g., S. horneri, Saccharina japonica, and Undaria pinnatifida) and commercial abalone feed, together with coffee waste. Heat map analysis indicated greater attraction by the kelp S. japonica than by S. horneri and commercial feed, which showed similar preference levels. Feeding preference based on the area of Avicel eaten by abalone showed a significant preference for U. pinnatifida over S. horneri (feeding area: 68.6 ± 20.1% vs. 37.5 ± 22.4%, p < 0.05). Additionally, the feeding area was significantly greater for plates with S. japonica than for plates with S. horneri (44.0 ± 16.6% vs. 22.6 ± 15.4%, p < 0.05). There was no significant difference in feeding area between commercial feed and S. horneri (31.7 ± 11.6% vs. 31.6 ± 20.2%, p > 0.05). The methanol extracts attracted abalone in the following order: U. pinnatifida > S. horneri > S. japonica > commercial feed > coffee waste. To determine the attractive effects of the components of methanol extracts, mixtures of methanol extracts of commercial feed with increasing amounts of S. horneri were examined. The results showed a significant increase in feeding preference upon addition of S. horneri up to 50% and 75%, suggesting its potential for use as an appetite-enhancing feed additive. This study identified conditions that can be successfully used to monitor the movement of Pacific abalone; the results of preference analysis confirmed that abalone exhibited similar attraction and feeding preference for S. horneri, compared with commercial feed.

• Safety and Health at Work
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• v.14 no.2
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• pp.193-200
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• 2023

Background: International evidence shows that mining workers are at greater risk of suicide than other workers; however, it is not known whether this applies to the Australian mining sector. Methods: Using data from the National Coronial Information System, rates of suicide among male mining workers were compared to those of three comparators: construction workers, mining and construction workers combined, and all other workers. Age-standardized suicide rates were calculated for 2001-2019 and across three intervals '2001-2006', '2007-2011', and '2012-2019'. Incidence rate ratios for suicide were calculated to compare incidence rates for mining workers, to those of the three comparative groups. Results: The suicide rate for male mining workers in Australia was estimated to be between 11 and 25 per 100,000 (likely closer to 25 per 100,000) over the period of 2001-2019. There was also evidence that the suicide rate among mining workers is increasing, and the suicide rate among mining workers for the period 2012-2019 was significantly higher than the other worker group. Conclusions: Based on available data, we tentatively deduce that suicide mortality among male mining workers is of concern. More information is needed on both industry and occupation of suicide decedents in order to better assess whether, and the extent to which, mining workers (and other industries and occupations) are at increased risk of suicide.

• Journal of Software Assessment and Valuation
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• v.15 no.2
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• pp.121-128
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• 2019

Computing systems have various vulnerabilities to cyber attacks. In particular, various cyber attacks that are intelligent in the information society have caused serious social problems and economic losses. Traditional security systems are based on misuse-based technology, which requires the continuous updating of new attack patterns and the real-time analysis of vast amounts of data generated by numerous security devices in order to accurately detect. However, traditional security systems are unable to respond through detection and analysis in real time, which can delay the recognition of intrusions and cause a lot of damage. Therefore, there is a need for a new security system that can quickly detect, analyze, and predict the ever-increasing cyber security threats based on machine learning and big data analysis models. In this paper, we present a IDS model that combines machine learning and big data technology.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2022.09a
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• pp.99-99
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• 2022

Artemisia fukudo is a biennial plant and has been reported to have anticancer, anti-melanogenesis, and anti-inflammatory effects. However, it is difficult to produce biomass from A. fukudo, so it is not used as a material for cosmetics or pharmaceuticals. In vitro culture can stably produce biomass throughout the year. In this study, the culture system for producing the highest biomass and bioactive substances was compared. Ex vitro plants were collected in Pyoseon-eup, Jeju island in May 2021, and in vitro culture was harvested after culturing for 8 weeks (plantlet) and 4 weeks (adventitious roots), respectively. After harvest, total polyphenol content (TPC), total flavonoid content (TFC), and DPPH scavenging activity were analyzed. In biomass production, adventitious roots (FW: 5.1 g·100 ml^-1, DW: 0.6 g·100 ml^-1) were about 4 times higher than that of plantlets (FW: 1.8 g·200 ml^-1, DW: 0.3 g·200 ml^-1). Both TPC and TFC were highest in ex vitro plants (9.2 ㎍·mL^-1, 31.6 ㎍·mL^-1), and were 3.0 times and 1.8 times higher than those of plantlets (3.0 ㎍·mL^-1, 17.8 ㎍·mL^-1), respectively. The IC₅₀ value of DPPH scavenging activity was also the best in ex vitro plants (69.8 ㎍·mL^-1), followed by root root (184.4 ㎍·mL^-1) and plants (325.3 ㎍·mL^-1) in that order. Through additional elicitor treatment, scale-up, and advanced compounds analysis such as HPLC, it can be used as an industrial material.

• The Journal of Korea Robotics Society
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• v.18 no.4
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• pp.444-455
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• 2023

In this report, a specialization plan for wearable robots by mission profile was investigated and analyzed to derive an application plan. The final goal of this study was to derive the operating requirements of wearable robots according to specialized plans, and to conduct a specialized study on wearable robots by mission profile through investigation/analysis of specialized plans for each mission profile. In the study, 1) Research on technology trends related to military wearable robots such as patents and papers, 2) Research/analysis of mission profiles to characterize wearable robots, 3) Analysis of wearable robot specialization plans according to mission profiles, and 4) Requirements for wearable robot operation were derived. In the first time of the study, a survey on technology trends related to wearable robots for soldiers such as patents and papers was completed, and a military consultative body was conducted to derive measures to characterize wearable robots. In addition, a survey was conducted on mission profiles, and the second time study derived Key Performance Parameters (KPP) for operational performance, core performance, and system performance based on scenarios by mission profile. However, it is revealed that the KPP derived from the research results was not covered in this paper because it was judged that more in-depth research was needed prior to disclosure. In order to prepare for future battlefield situations and increase the usability of wearable robots, this study was conducted to characterize wearable robots by considering the characteristics of soldiers' equipment according to mission profiles and to characterize wearable robots by mission profile.

• Korean Journal of Culture and Social Issue
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• v.9 no.1
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• pp.81-114
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• 2003

This study examines the basis and change of delinquent behavior among Korean adolescents. Theoretical framework was developed and qualitative analysis of delinquency behavior was examined. In order to understand the basis and change of juvenile delinquency, the influence of family environment, school environment and individual factors were investigated through cross-sectional and longitudinal studies. The results of the findings can be summarized into the following six main points: 1) two subcultures of adolescent functioning could be ascertained, 2) the decrease in social support and increase in moral disengagement were directly related to a rise in juvenile delinquency, 3) family disintegration contributed to juvenile delinquency, 4) peer influence help to raise juvenile delinquency, 5) schools were unable to give hope to those students who were not doing well in school and were ineffective in dealing with juvenile delinquents, and 6) the phenomenon of juvenile delinquency points to the importance of opening up the closed school system and closed society, allowing individual diversity and skills to be recognized.

• The Journal of the Convergence on Culture Technology
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• v.9 no.5
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• pp.951-956
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• 2023

In the current situation where systematic and active disaster management is becoming more important, domestic libraries do not have their own disaster management plans or support systems. In order to improve these problems, this study looked at overseas cases. Among them, we looked at Japan, where related cases and research are actively underway due to its exposure to various geopolitical disasters. In particular, we focused on cases of public-private cooperation established after the Great East Japan Earthquake. Association's Library Disaster Response Committee and saveMALK, a voluntary network of experts. The Library Disaster Response Committee played a central role in organizing donations and volunteer activities, and saveMALK played a role in collecting and sharing information by forming a collective intelligence among relevant experts. This analysis of the Japanese case has positive implications for building collaborative disaster management system.

• Journal of Navigation and Port Research
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• v.48 no.3
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• pp.171-180
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• 2024

Recently, there has been a global emphasis on decarbonization in order to address climate change and achieve carbon neutrality by 2050. In line with government regulations, domestic port authorities have also started participating in this global agenda. Since 2010, when decarbonization became an important task in ports, there have been studies analyzing the environmental efficiency of container terminals, taking into account undesirable outputs. However, most of these previous studies only measured carbon dioxide emissions based on Tier 1, whereas this study is the first to analyze the environmental efficiency of South Korea's container terminals based on Tier 3, as presented in the IPCC guidelines. The study considered 17 container terminal operators in South Korea as decision-making units and used the DEA-SBM Model. Subsequently, an Undesirable Outputs Model was conducted to calculate the environmental efficiency.