• Title/Summary/Keyword: Conduct problem

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Energy-efficient Power Allocation based on worst-case performance optimization under channel uncertainties

  • Song, Xin;Dong, Li;Huang, Xue;Qin, Lei;Han, Xiuwei
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.14 no.11
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    • pp.4595-4610
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    • 2020
  • In the practical communication environment, the accurate channel state information (CSI) is difficult to obtain, which will cause the mismatch of resource and degrade the system performance. In this paper, to account for the channel uncertainties, a robust power allocation scheme for a downlink Non-orthogonal multiple access (NOMA) heterogeneous network (HetNet) is designed to maximize energy efficiency (EE), which can ensure the quality of service (QoS) of users. We conduct the robust optimization model based on worse-case method, in which the channel gains belong to certain ellipsoid sets. To solve the non-convex non-liner optimization, we transform the optimization problem via Dinkelbach method and sequential convex programming, and the power allocation of small cell users (SCUs) is achieved by Lagrange dual approach. Finally, we analysis the convergence performance of proposed scheme. The simulation results demonstrate that the proposed algorithm can improve total EE of SCUs, and has a fast convergence performance.

ROBUST PORTFOLIO OPTIMIZATION UNDER HYBRID CEV AND STOCHASTIC VOLATILITY

  • Cao, Jiling;Peng, Beidi;Zhang, Wenjun
    • Journal of the Korean Mathematical Society
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    • v.59 no.6
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    • pp.1153-1170
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    • 2022
  • In this paper, we investigate the portfolio optimization problem under the SVCEV model, which is a hybrid model of constant elasticity of variance (CEV) and stochastic volatility, by taking into account of minimum-entropy robustness. The Hamilton-Jacobi-Bellman (HJB) equation is derived and the first two orders of optimal strategies are obtained by utilizing an asymptotic approximation approach. We also derive the first two orders of practical optimal strategies by knowing that the underlying Ornstein-Uhlenbeck process is not observable. Finally, we conduct numerical experiments and sensitivity analysis on the leading optimal strategy and the first correction term with respect to various values of the model parameters.

An Analysis of Effective Factors in Public Awareness Campaigns through Facebook: Focus on Fine Dust Issues

  • Nguyen, Thanh-Mai;Jo, Sam-sup
    • International Journal of Contents
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    • v.17 no.4
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    • pp.35-45
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    • 2021
  • In this study, we analyzed the factors that affect public awareness campaigns on social media platforms and developed an integrated model for measuring the persuasiveness of environmental social media campaigns. A survey questionnaire was created and distributed on Facebook with the goal of reaching individuals in their 20s and 40s in Vietnam, and 395 valid replies were gathered. The findings showed that the STOPS was reconfirmed as a suitable theoretical framework for analyzing the public's behaviour intention to conduct information related to the issue of fine dust, especially on social media. Furthermore, it also showed that social media efficacy has a moderating effect on the relationship between public's situational recognition and informational behaviour intention. This suggested that through social media platforms, personal characteristics play a vital part in developing effective environmental campaigns. Implications for both theory and practice were discussed.

ENHANCEMENT OF AVAILABILITY OF 4D SIMULATION BASED ON BUILDING INFORMATION MODEL TECHNOLOGY

  • Jong Jin Park;Eon Yong Kim;Hyun Cho;Han Jong Jun
    • International conference on construction engineering and project management
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    • 2009.05a
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    • pp.579-586
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    • 2009
  • 4D simulation integrates the 3 dimensional model of a building with the construction schedule, and it leads to the possibility of virtually checking the construction process and the building itself in advance. However, the existing problem of 4D simulation is the difference between the demands of architects, engineers, and construction site workers in 4D simulation. This study suggests the possible way to enhance the availability of 4D simulation, considering more the practical demands from the construction site. In order to conduct this study, we build a 3D BIM model of a business-residential complex and link the model with the pre-defined construction schedule in order to make a 4D simulation. This study concludes with the optimized 4D simulation methodology based on BIM model considering the demands in perspective of the construction site. It would contribute to the harmonic collaboration among architects, engineers, and labors in the construction site when using 4D simulation based on BIM model.

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Distribution of Welding Residual Stresses in Laser Welds with the Nail-head shape

  • Kim, Y.P.;Joo, S.M.;Bang, H.S.
    • International Journal of Korean Welding Society
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    • v.3 no.1
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    • pp.17-22
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    • 2003
  • During the laser welding, weldments are suddenly heated and cooled by laser beam of high density energy. This phenomenon gives an occasion to complex welding residual stresses, which have a great influence on structural instability, in laser welds. However, relevant researches on this field are not sufficient until now and residual stress measurements have experimental and practical limitations. From these reasons, a numerical simulation may be attractive in order to solve the residual stress problem. For clarifying the distribution of heat and welding residual stresses in laser welds with the nail-head shape, authors conduct the finite element analysis (two-dimensional unstationary heat conduction & thermal elastic and plastic analysis). From the results, we can confirm the stress concentration occurs at the place of melting line shape changed in laser welds with the nail-head shape.

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Multi-task learning with contextual hierarchical attention for Korean coreference resolution

  • Cheoneum Park
    • ETRI Journal
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    • v.45 no.1
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    • pp.93-104
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    • 2023
  • Coreference resolution is a task in discourse analysis that links several headwords used in any document object. We suggest pointer networks-based coreference resolution for Korean using multi-task learning (MTL) with an attention mechanism for a hierarchical structure. As Korean is a head-final language, the head can easily be found. Our model learns the distribution by referring to the same entity position and utilizes a pointer network to conduct coreference resolution depending on the input headword. As the input is a document, the input sequence is very long. Thus, the core idea is to learn the word- and sentence-level distributions in parallel with MTL, while using a shared representation to address the long sequence problem. The suggested technique is used to generate word representations for Korean based on contextual information using pre-trained language models for Korean. In the same experimental conditions, our model performed roughly 1.8% better on CoNLL F1 than previous research without hierarchical structure.

Performance Evaluation of Tree Routing in Large-Scale Wireless Sensor Networks (대규모 센서네트워크에서의 트리라우팅 성능평가)

  • Beom-Kyu Suh;Ki-Il Kim
    • IEMEK Journal of Embedded Systems and Applications
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    • v.18 no.2
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    • pp.67-73
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    • 2023
  • Tree routing is one of appropriate routing schemes in wireless sensor network because the complexity of this approach is relatively low. But, congestion at a specific node may happen because a parent node toward a sink node is usually selected in one hop way, specially where large number of node are deployed. As feasible solution for this problem, multiple paths and sinks schemes can be applied. However, the performance of these schemes are not proved and analyzed yet. In this paper, we conduct diverse simulaton scenarios performance evaluation for these cases to identify the improvement and analyze the impact of schemes. The performance is measured in the aspects of packet transmission rate, throughput, and end-to-end delay as a function of amount of network traffic.

Numerical Nonlinear Stability of Traveling Waves for a Chemotaxis Model

  • Min-Gi Lee
    • Kyungpook Mathematical Journal
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    • v.63 no.2
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    • pp.141-154
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    • 2023
  • We study the stability of traveling waves of a certain chemotaxis model. The traveling wave solution is a central object of study in a chemotaxis model. Kim et al. [8] introduced a model on a population and nutrient densities based on a nonlinear diffusion law. They proved the existence of traveling waves for the one dimensional Cauchy problem. Existence theory for traveling waves is typically followed by stability analysis because any traveling waves that are not robust against a small perturbation would have little physical significance. We conduct a numerical nonlinear stability for a few relevant instances of traveling waves shown to exist in [8]. Results against absolute additive noises and relative additive noises are presented.

A Case Study of Community-based Service Learning Outcomes (지역사회기반학습 수업 운영 사례와 효과 연구)

  • Lee, Joosung
    • Journal of Engineering Education Research
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    • v.26 no.4
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    • pp.36-46
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    • 2023
  • This paper presents a case study and online-offline (hybrid) course structure for project-oriented community-based service learning in order to solve real-world problems for society. It examines social issues and conduct student projects to develop solutions that can generate sustainable value. This course helps students to use their major knowledge to assess and solve the problems faced by the local community. The outcomes of this course conducted via online lectures and offline project activities are discussed. The operation of this blended type of social problem-solving course is also stated.

Hazard Assessment Methodology Based on Target Level of Safety for CNS/ATM System (항행 안전 시스템을 위한 안전 목표 수준 기반 위험 평가 방법론)

  • Lee, Hongseok;Jo, Sanghoon
    • Journal of Advanced Navigation Technology
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    • v.20 no.4
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    • pp.285-291
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    • 2016
  • Safety assessment is an essential activity for developing a system in the CNS/ATM domain. Up to now, there are many reference materials, but there is nothing that definitely specifies what to do and how to apply in the CNS/ATM. Another problem is that software assurance level has to be determined for a software under development. But there is nothing that defines a determination scheme of software assurance level. To solve these problems, this paper proposes a method to conduct a hazard assessment based on target level of safety defined in ICAO Doc 9689. To be applied generally in CNS/ATM domain, it mathematically defines procedures of hazard assessment. And it defines severity classification, probability, and safety objective of a system, which are necessary for hazard assessment, and it describes a method to apply event tree analysis process in order to conduct a hazard assessment.