• The Transactions of the Korean Institute of Power Electronics
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• v.15 no.4
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• pp.296-308
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• 2010

This paper proposes a design of the three-parallel converter system and grid-connection technique for a PMSG based wind turbine systems. The back-to-back converter of the PMSG based wind turbine system is directly connected to the grid so that both the power devices and the filters are needed to have large power ratings. The three-parallel converter configuration can reduce the required power ratings of the devices and filters. However, the three-parallel converter can cause circulating currents. These circulating currents can be suppressed by sellecting proper inner inductance at each leg. An LCL filter design is used to meet the THD regulations. The latent resonance caused by the LCL filter is compensated by an active damping method without additional loss. The decline of the power quality caused by the unbalanced and distorted grid voltages is also compensated with an additional compensation algorithm. The simulation and experimental results show that the proposed system and compensation methods are effective for the wind turbine systems.

• Environmental and Resource Economics Review
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• v.32 no.3
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• pp.149-166
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• 2023

The emissions trading system, introduced to reduce greenhouse gas emissions, experienced a sharp increase in emission allowance prices during the second plan period (2018-2020), which led to an increase in the demand for smooth supply and demand of emission allowances, while suppliers anticipating a shortage of emission allowances in the future did not participate in trading. Therefore, the authority temporarily revised the guidelines to ensure that the amount of allowances carried forward is proportional to the trading volume as a market stabilization measure. Through an optimization process using a dynamic nonlinear mathematical model, this paper analyzes the impact of the government's intervention on the carryover policy on GHG emission reductions and emission allowance market prices. According to the simulation analysis results, banking regulations could cause a decline in prices during the regulation period, even though the initial policy was predicted to be adopted.

• The Journal of Korean Physical Therapy
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• v.31 no.2
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• pp.129-133
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• 2019

Purpose: This study aimed to investigate effect of ankle instability on peripheral muscle activation among female ballet dancers to provide information on the development of prevention programs for ankle injury rehabilitation. Methods: 32 female ballet dancers were randomly divided into two groups: experience ankle sprain group (n=16, age, $20.7{\pm}0.8years$, BMI $18.6{\pm}1.2kg/m2$) and non-experience ankle sprain group (n=16, $age=21.0{\pm}0.8years$, BMI $19.6{\pm}2.0kg/m2$). Activation of the peroneus longus, tibialis anterior muscle, and gastrocnemius during vertical landing, half pointe, and gait between the two groups were measured. Body composition analyzer was used to examine skeletal muscle mass and body fat mass. Results: A total of 32 patients were included. In the experience ankle sprain group (n=16: left sprain 14, right sprain 2), average ankle sprain injury occurred 7.5 months before the study. The average age of the dancers in the experience ankle sprain group and non-experience ankle sprain group was $20.7{\pm}0.8$ and $21.0{\pm}0.8years$, major period was $64.5{\pm}23.8$ and $71.6{\pm}25.8months$, BMI was $18.6{\pm}1.2$ and $19.5{\pm}2.0kg/m2$, respectively. No significant differences were found on body composition between the two groups (p>0.05). The experience ankle sprain group showed significantly lower tibialis anterior and peroneus longus muscle activation (p<0.5), while gastrocnemius muscle activation appeared to be significantly higher (p<0.05) during landing, half pointe, and normal gait. Conclusion: Ankle sprain can cause a decline in peripheral muscle activation and coordination, which increased the risk for repetitive ankle sprain in the future. Moreover, ankle peripheral muscle selective strength training, coordination program development, and application need to be considered to prevent ankle sprain.

• Korean Journal of Soil Science and Fertilizer
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• v.16 no.4
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• pp.358-367
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• 1983

Antibiotic-resistant strains of Salmonella typhimurium and Klebsiella pneumoniae died readily after their addition to raw sewage, but they grew in sterilized sewage. The decline was not a result of antibiotic stresses, and because the bacteria were able to survive in large numbers for at least 15 days in solutions containing no organic nutrients, it was not a result of competition. Toxin production, bacteriophages, and Bdellovibrio did not cause the disappearance of the two bacterial species. A decline was also evident if the sewage was first passed through a $3-{\mu}m$ filter or treated with cycloheximide or cycloheximide plus nystatin, but protozoa developed under these conditions. Little or no decline occurred if the sewage was filtered and treated with the eucaryotic inhibitors before adding S. typhimurium or K. pneumoniae, and protozoa were not detected. S. typhimurium increased in abundance if cycloheximide, streptomycin, and erythromycin or large amounts of glucose were added to sewage. Tetrahymena thermophilus did not significantly reduce the population of S. typhimurium in buffer when the density of the bacterium was about $10^4/ml$. However, when more than $10^8$ Enterobacter agglomerans cells per ml were added to the buffer, T. thermophilus reduced the abundance of E. agglomerans and S. typhimurium to $10^6$ and 10/ml, respectively. The density of S. typhimurium was further decreased by a second increment of E. agglomerans cells. The disappearance of S. typhimurium and K. pneumoniae from sewage thus is the result of predation by protozoa. It is proposed that predators will eliminate a prey species from a natural environment when an alternate prey is present at concentrations above the threshold number for active feeing by the predator and when the rate of growth of the prey is less than the rate of predation.

• The Korean Journal of Physiology and Pharmacology
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• v.18 no.6
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• pp.509-516
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• 2014

Radiation therapy for variety of human solid tumors utilizes mechanism of cell death after DNA damage caused by radiation. In response to DNA damage, cytochrome c was released from mitochondria by activation of pro-apoptotic Bcl-2 family proteins, and then elicits massive $Ca^{2+}$ release from the ER that lead to cell death. It was also suggested that irradiation may cause the deregulation of $Ca^{2+}$ homeostasis and trigger programmed cell death and regulate death specific enzymes. Thus, in this study, we investigated how cellular $Ca^{2+}$ metabolism in RKO cells, in comparison to radiation-resistant A549 cells, was altered by gamma (${\gamma}$)-irradiation. In irradiated RKO cells, $Ca^{2+}$ influx via activation of NCX reverse mode was enhanced and a decline of $[Ca^{2+}]_i$ via forward mode was accelerated. The amount of $Ca^{2+}$ released from the ER in RKO cells by the activation of $IP_3$ receptor was also enhanced by irradiation. An increase in $[Ca^{2+}]_i$ via SOCI was enhanced in irradiated RKO cells, while that in A549 cells was depressed. These results suggest that ${\gamma}$-irradiation elicits enhancement of cellular $Ca^{2+}$ metabolism in radiation-sensitive RKO cells yielding programmed cell death.

• Korean Journal of Cognitive Science
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• v.31 no.3
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• pp.55-76
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• 2020

Sociability is an inherent part of human life and also possesses an important value as a comprehensive ability. While the lack of sociability has been pointed out as a representative problem of game use in general, this paper analyzed studies on the relationship between online video games and social competence. In this field, the view that the relationship in the online game may replace or complement the actual relationship and will potentially hinder the development of sociability currently faces a conflict with the opinion that online video games may not directly have a negative effect on sociability but rather result in a positive outcome by providing a social learning space. In a large scale survey that measured the use of online games, psychological characteristics, and social competence, no distinct relationship between game use and degradation of sociability was observed. Based on this analysis, we suggest that efforts are necessary to break away from the stereotype that online game play may cause a decline in sociability and to improve the validity of related research.

• Journal of the Korean Institute of Landscape Architecture
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• v.45 no.5
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• pp.14-28
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• 2017

Mt. Seunghak's Miscanthus sinensis community is not only a landscape resource in terms of cultural services within the Ecosystem Services but also a site that is visited by many mountaineers in autumn. As the current Miscanthus sinensis community has been experiencing a rapid decline due to Korean forest succession characteristics, ongoing artificial management is thought to be needed for landscape resource use. The purpose of this study was to determine growth environment characteristics and the cause of the rapid decline of the Miscanthus sinensis community in Mt. Seunghak, which is located inside a large city with a large scale and outstanding accessibility. As the Miscanthus sinensis community is the representative early vegetation that appears temporarily in dry, barren soil, the Miscanthus sinensis community in Korean forest succession tends to be unsustainable. As the current soil on Mt. Seunghak is inappropriately fertile for the Miscanthus sinensis community, other wetland woody plant communities are anticipated to succeed it. If Miscanthus sinensis community maintenance is needed for Miscanthus sinensis landscape scenery, various alternatives apart from overall Miscanthus sinensis community maintenance should be determined for cost-effective management. For example, while many byways toward the inside of the Miscanthus sinensis community have affected the Miscanthus sinensis community growth environment, the installation of wooden fences and ropes has been a control in approach. As a result of this positive effect, many byways toward the inside of Miscanthus sinensis community have been restored naturally. Through viewable range analysis, as good scenery sites on the observatory have a good viewable range on the main trail as well, if these scenery sites are intensively managed, effective Miscanthus sinensis ccommunity management will be done despite maintenance budget cutbacks. This study is expected to be used as a basic material regarding the alternatives for a sustained Miscanthus sinensis community and the possibility of cultivating other growth in poor soils of fallow fields and unused land.

• The Journal of the Convergence on Culture Technology
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• v.9 no.6
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• pp.187-192
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• 2023

A problem user in a library refers to a person who harasses others or causes a disturbance through inappropriate behavior in the library. Users' continued problematic behavior reduces the work productivity of librarians and at the same time causes inconvenience to other users. This may cause a decline in the free use of public libraries. In Korea, a user response manual has been developed to guide librarians to respond wisely to user problem behavior. However, it is true that most of the content provides guidance on how to communicate with problem users, and there is a lack of countermeasures to stipulate and regulate follow-up measures against them. The goal of this study is to further systematize response and organize them into written regulations. To this end, this study to examine regulations and legal battles surrounding problem users in oversea public libraries and to examine what can be applied in Korea in the future.

• Journal of Korea Game Society
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• v.15 no.4
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• pp.79-92
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• 2015

The trend in the domestic MMORPG online game market is on decline because of the change in customers attitude and the advent of mobile or foreign games. The underlying cause of depressed domestic game market is that it has been failing to provide quality service arising from not revising existing game design. For this reason, this paper sets out to gather game users' opinions and to analyze successful domestic and foreign games comparatively to approve the importance and necessity of scenario development and to solve current problems in the MMORPG market. As one solution, this paper proposes a new design method, TIME FLOW scenario technique. This technique aims to establish a system in which story and environment change as time progresses and thus can provide different contents to its users over time. It is expected to enable a new frame for game design environment and to restructure education environment for human resource cultivation.

• Journal of the Korea Society of Computer and Information
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• v.19 no.8
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• pp.83-93
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• 2014

Research into recommendation systems for wellness content has focused on representative research on the convergence of wellness and information technology, as interest in wellness has recently increased. But existing research is not suitable because it uses only one or two of the five wellness areas: physical, emotional, social, intellectual, and spiritual. And It cause decline of reliability and satisfaction for recommendation. Thus, a wellness areal feature analysis and integration management technique is needed. In this paper, suggest meta-data configuration and feature analysis technique of content. Also Cosine similarity of wellness areal features of the content was analyzed by applying a wellness areal score calculated in this way and by suggested wellness areal detailed properties and a measurement system to verify the efficiency of this research. This allows the wellness features of contents analyzed, and even will be able to personalized recommendations service for wellness.