• International Journal of Control, Automation, and Systems
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• v.5 no.6
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• pp.674-680
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• 2007

The probabilistic roadmap (PRM) method, which is a popular path planning scheme, for a manipulator, can find a collision-free path by connecting the start and goal poses through a roadmap constructed by drawing random nodes in the free configuration space. PRM exhibits robust performance for static environments, but its performance is poor for dynamic environments. On the other hand, reinforcement learning, a behavior-based control technique, can deal with uncertainties in the environment. The reinforcement learning agent can establish a policy that maximizes the sum of rewards by selecting the optimal actions in any state through iterative interactions with the environment. In this paper, we propose efficient real-time path planning by combining PRM and reinforcement learning to deal with uncertain dynamic environments and similar environments. A series of experiments demonstrate that the proposed hybrid path planner can generate a collision-free path even for dynamic environments in which objects block the pre-planned global path. It is also shown that the hybrid path planner can adapt to the similar, previously learned environments without significant additional learning.

• Journal of the Korean Society of Safety
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• v.12 no.3
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• pp.67-75
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• 1997

This paper presents a study on the application of Asynchronous Team(A-Team) theory for QVC(Reactive power control) and security assessment in a power system. Reactive power control problem is the one of optimally establishing voltage level given reactive power sources, which is very important problem to supply the demand without interruption and needs methods to alleviate a bus voltage limit violation more quickly. It can be formulated as a mixed-integer linear programming(MILP) problem without deteriorating of solution accuracy to a certain extent. The security assessment is to estimate the relative robustness of the system and deterministic approach based on AC load flow calculations is adopted to assess it, especially voltage security. A distance measure, as a measurement for voltage security, is introduced. In order to analyze the above two problem, reactive power control and static security assessment, In an integrated fashion, a new organizational structure, called an A-team, is adopted. An A-team is well-suited to the development of computer-based, multi-agent systems for operation of large-scaled power systems. In order to verify the usefulness of the suggested scheme herein, modified IEEE 30 bus system is employed as a sample system. The results of a case study are also presented.

• The Journal of Asian Finance, Economics and Business
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• v.5 no.2
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• pp.63-72
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• 2018

Researches based on the pattern of planned behavior holds that the three variables of entrepreneurial attitudes, subjective norms, and perceived behavior control influence each other and influence entrepreneurial intentions respectively. However, there are also different, even conflicting research conclusions that continue to emerge. Researches based on the pattern of alertness, believe that profit opportunities and individuals' pursuit to truth are the driving forces. Many scholars have demonstrated the impact of individual entrepreneurial alertness on entrepreneurial intentions. However, as an exogenous causal agent, profit opportunities have a logical problem: if there are no other assumptions, the mere existence of opportunities does not adequately explain entrepreneurial alertness. To address this gap, this study considered samples from mainland China, where entrepreneurial activities are very active currently, to test the role that entrepreneurial alertness is assumed to play in the planned behavior model. The results show that the three dimensions of alertness, individually partly intermediate the influence of entrepreneurial attitude on entrepreneurial intention, the influence of subjective norms on entrepreneurial intention, and that of perceived behavior control on entrepreneurial intention. This article studied the production of entrepreneurial intention by integrating the two patterns of planned behavior and alertness through empirical analysis, and opened up a new field for subsequent research on entrepreneurial intention.

• Restorative Dentistry and Endodontics
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• v.41 no.4
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• pp.296-303
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• 2016

Objectives: The purpose of the present study was to evaluate the effects of proanthocyanidin (PAC), a crosslinking agent, on the physical properties of a collagen hydrogel and the behavior of human periodontal ligament cells (hPDLCs) cultured in the scaffold. Materials and Methods: Viability of hPDLCs treated with PAC was measured using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The physical properties of PAC treated collagen hydrogel scaffold were evaluated by the measurement of setting time, surface roughness, and differential scanning calorimetry (DSC). The behavior of the hPDLCs in the collagen scaffold was evaluated by cell morphology observation and cell numbers counting. Results: The setting time of the collagen scaffold was shortened in the presence of PAC (p < 0.05). The surface roughness of the PAC-treated collagen was higher compared to the untreated control group (p < 0.05). The thermogram of the crosslinked collagen exhibited a higher endothermic peak compared to the uncrosslinked one. Cells in the PAC-treated collagen were observed to attach in closer proximity to one another with more cytoplasmic extensions compared to cells in the untreated control group. The number of cells cultured in the PAC-treated collagen scaffolds was significantly increased compared to the untreated control (p < 0.05). Conclusions: Our results showed that PAC enhanced the physical properties of the collagen scaffold. Furthermore, the proliferation of hPDLCs cultured in the collagen scaffold crosslinked with PAC was facilitated. Conclusively, the application of PAC to the collagen scaffold may be beneficial for engineering-based periodontal ligament regeneration in delayed replantation.

• The Journal of Engineering Geology
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• v.33 no.3
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• pp.371-388
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• 2023

A stratum with a complex composition and a distributed low-permeability soil layer is difficult to remediate quickly because the soil remediation does not proceed easily. For efficient purification, the permeability should be improved and the soil remediation agent (H₂O₂) should be injected into the contaminated section to make sufficient contact with the TPH (Total petroleum hydrocarbons). This study analyzed a method for crack formation and effective delivery of the soil remediation agent based on pneumatic fracturing, plasma blasting, and vacuum suction (the PPV method) and compared its improvement effect relative to chemical oxidation. A demonstration test confirmed the effective delivery of the soil remediation agent to a site contaminated with TPH. The injection amount and injection time were monitored to calculate the delivery characteristics and the range of influence, and electrical resistivity surveying qualitatively confirmed changes in the underground environment. Permeability tests also evaluated and compared the permeability changes for each method. The amount of soil remediation agent injected was increased by about 4.74 to 7.48 times in the experimental group (PPV method) compared with the control group (chemical oxidation); the PPV method allowed injection rates per unit time (L/min) about 5.00 to 7.54 times quicker than the control method. Electrical resistivity measurements assessed that in the PPV method, the diffusion of H₂O₂2 and other fluids to the surface soil layer reduced the low resistivity change ratio: the horizontal change ratio between the injection well and the extraction well decreased the resistivity by about 1.12 to 2.38 times. Quantitative evaluation of hydraulic conductivity at the end of the test found that the control group had 21.1% of the original hydraulic conductivity and the experimental group retained 81.3% of the initial value, close to the initial permeability coefficient. Calculated radii of influence based on the survey results showed that the results of the PPV method were improved by 220% on average compared with those of the control group.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.47 no.6
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• pp.81-88
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• 2015

The molecular weight (MW) and crystallinity of cotton linter need to be controlled to be dissolved well in N-methylmorpholine N-oxide (NMMO) solvent for manufacturing regenerated fibers of clothing fabrics. Electron beam irradiation or sulfuric acid pre-treatment followed by alkaline peroxide bleaching has been used to control MW effectively and to improve brightness of cotton linter. Auto-hydrolysis of cotton linter without electron beam irradiation or chemical pre-treatment was found to be effective as an alternative pre-treatment method. Removal of metal ions, that hampered dissolution of cotton linter by NMMO, was also investigated when the auto-hydrolysis was accompanied with ionic polymers and chelating agent.

• International Journal of Computer Science & Network Security
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• v.21 no.9
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• pp.132-140
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• 2021

Under the mobile ad-hoc network system, the main reason for causing congestion is because of the limited availability of resources. On the other hand, the standardised TCP based congestion controlling mechanism is unable to control and handle the major properties associated with the shared system of wireless channels. It creates an effect on the design associated with suitable protocols along with protocol stacks through the process of determining the mechanisms of congestion on a complete basis. Moreover, when bringing a comparison with standard TCP systems the major environment associated with mobile ad hoc network is regraded to be more problematic on a complete basis. On the other hand, an agent-based mobile technique for congestion is designed and developed for the part of avoiding any mode of congestion under the ad-hoc network systems.

• International Journal of Advanced Culture Technology
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• v.11 no.1
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• pp.332-336
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• 2023

In this paper, we design and implement an ADHD diagnostic rating scale algorithm and virtual reality- based digital treatment by combining virtual reality technology that enables multiple access based on specialized medical data. The VR ADHD digital treatment to be implemented is intended to be applied directly to diagnosis and treatment of child/adolescent ADHD by applying various psychiatric treatment technologies. In order to evaluate the usability of the digital therapeutic agent developed in this paper, an expert group consisting of 2 males and 12 females "targeted counseling psychology majors at the Asian Dementia Center once a day for 3 weeks, ADHD VR-based digital therapeutics for children Experienced and usability evaluation conducted. As a final result of this thesis, it was possible to develop attentional concentration ability, working memory improvement ability, and impulsive control ability in four games of digital therapy, and it was possible to confirm significant results that can be expected to have ADHD therapeutic effects.

• The KIPS Transactions:PartC
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• v.15C no.6
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• pp.455-468
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• 2008

In this paper, we propose FAS model for establishing trust based on digital certificates in Grid security framework. The existing RBAC(Role Based Access Control) model is extended to provide permissions depending on the users‘ roles. The FAS model is designed for a system independent integrated Grid security by detailing and extending the fundamental architecture of user, role, and permission. FAS decides each user’s role, allocates access right, and publishes attribute certificate. FAS is composed of three modules: RDM, PCM, and CCM. The RDM decides roles of the user during trust negotiation process and improves the existing low level Grid security in which every single user maps a single shared local name. Both PCM and CCM confirm the capability of the user based on various policies that can restrict priority of the different user groups and roles. We have analyzed the FAS strategy with the complexity of the policy graph-based strategy. In particular, we focused on the algorithm for constructing the policy graph. As a result, the total running time was significantly reduced.

• Journal of the Korea Society for Simulation
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• v.30 no.1
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• pp.43-54
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• 2021

Since COVID-19 (Severe acute respiratory syndrome coronavirus type 2, SARS-Cov-2) was first discovered at the end of 2019, it has spread rapidly around the world. This study introduces an agent-based simulation model representing COVID-19 spread in South Korea to investigate the effect of detect level (contact tracing) on the virus spread. To develop the model, related data are aggregated and probability distributions are inferred based on the data. The entire process of infection, quarantine, recovery, and death is schematically described and the interaction of people is modeled based on the traffic data. A composite logistic functions are utilized to represent the compliance of people to the government move control such as social distancing. To demonstrate to effect of detect level on the virus spread, detect level is changed from 0% to 100%. The results indicate active contact tracing inhibits the virus spread and the inhibitory effect increases geometrically as the detect level increases.