• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.446-451
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• 2003

This paper presents some examples of active control of flow-induced vibration using piezoelectric actuators. The flutter phenomenon, which is the dynamic instability of structure due to mutual interaction among inertia, stiffness, and aerodynamic forces, may cause catastrophic structural failure, and therefore the active flutter suppression is one of the main objectives of the aeroelastic control. Active flutter control has been numerically and experimentally studied for swept-back lifting surfaces using piezoelectric actuation. A finite element method, a panel aerodynamic method, and the minimum state space realization are involved in the development of the governing equation, which is efficiently used for the analysis of the system and design of control laws with modern control framework. The active control suppressed flow-induced vibrations and extended the flutter speed around by 10%. Another representative flow-induced vibration phenomenon is the oscillation of blunt bodies due to the vortex shedding. In general, it is quite difficult to set up the numerical model because of the strong non-linearity of the vortex shedding structure. Therefore, we applied adaptive positive position feedback controller, which requires no pre-determined model of the plant, and successfully suppressed the flow-induced vibration.

• Korean Journal of Health Education and Promotion
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• v.31 no.1
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• pp.57-70
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• 2014

Objectives: The purpose of this study was to build a conceptual framework of bullying in nursing workplace. Methods: A comprehensive literature review was conducted to identify concepts in relation to bullying in nursing workplace by searching research articles published between 1995 and 2013. In-depth interviews were performed with 14 nurses who experienced bullying at work. The Hybrid Model was applied for concept analysis which led to identify attributes of bullying in nursing workplace. Results: The antecedents of bullying in nursing workplace were offenders, victims, and administrators. They create negative effects on organizational culture and imbalance of power between authority and subordinate workers in the organization. Bullying in nursing workplace that occurred in the forms of inefficient organizational culture, imbalance of power, and the vulnerability of individual or individuals and groups of individuals formed an unstable dynamic. It is expressed as verbal and nonverbal bullying, work-related bullying, and external threats. Consequently, workplace bullying causes physical and psychological withdrawal and increased negative energy in an organization. Conclusions: Workplace bullying consisted of verbal abuse, alienation, unreasonable work processes, restriction on work-related rights, and external threat.

• The Southeast Asian review
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• v.21 no.2
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• pp.217-261
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• 2011

This study is an attempt to construct a basic framework of analysis about China's political and economic influence on Southeast Asia through traditional Sinocentrism, anti-colonial nationalism, Cold War socialism and post-Cold War capitalism. As to the historical status of Southeast Asia vis-a-vis external forces such as India, China and the West, the colonial discourse tends to put excessive emphasis upon its dependence, and the posy-colonial discourse upon its autonomy. However, this study elucidates the political and economic interactions between China and Southeast Asia in a dynamic perspective, focusing on their reciprocal interactions beyond the essentially static dichotomy of autonomy and dependence. Chinese influence on Southeast asia can be divided into active and reactive one, with the former referring to direct and intended consequences and the latter to indirect and unintended consequences. In the historical process of active and reactive influence, both China and Southeast Asia were fundamentally proactive actors. Thus, the autonomy or dependence of Southeast Asia is just a question of relative one, with its actual extent and degree varying with specific spatial and temporal conditions.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.11
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• pp.4224-4243
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• 2021

Cognitive radio (CR) is a feasible intelligent technology and can be used as an effective solution to spectrum scarcity and underutilization. As the key function of CR, cooperative spectrum sensing (CSS) is able to effectively prevent the harmful interference with primary users (PUs) and identify the available spectrum resources by exploiting the spatial diversity of multiple secondary users (SUs). However, the open nature of the cognitive radio networks (CRNs) framework makes CSS face many security threats, such as, the malicious user (MU) launches Byzantine attack to undermine CRNs. For this aim, we make an in-depth analysis of the motive and purpose from the MU's perspective in the interweave CR system, aiming to provide the future guideline for defense strategies. First, we formulate a dynamic Byzantine attack model by analyzing Byzantine behaviors in the process of CSS. On the basis of this, we further make an investigation on the condition of making the fusion center (FC) blind when the fusion rule is unknown for the MU. Moreover, the throughput and interference to the primary network are taken into consideration to evaluate the impact of Byzantine attack on the interweave CR system, and then analyze the optimal strategy of Byzantine attack when the fusion rule is known. Finally, theoretical proofs and simulation results verify the correctness and effectiveness of analyses about the impact of Byzantine attack strategy on the throughput and interference.

• International conference on construction engineering and project management
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• 2020.12a
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• pp.96-102
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• 2020

The construction industry remains serious accidents, injuries, and fatalities due to it's unique, dynamic, and temporary nature. On workplace sites, Safety pre-task planning is one of the efforts to minimize injuries and help construction personnel to identify potential hazards. However, the working conditions are complicated. Many activities, including tasks or job steps, are executing at the same time and place. It may lead to an increase in the risks from simultaneous tasks. This paper contributes to addressing this issue by introducing a safety risk interaction analyzing framework. To accomplish this objective, accident reports of the Occupational Safety and Health Administration (OSHA) are investigated. The pairs of task incompatibility, which have time-space conflicts and lead to incidents, are found. Ontology technology is applied to build the risk database, in which the information is acquired, structuralized. The proposed system is expected to improve pre-task planning efficiency and relieve the burdens encountered by safety managers. A user scenario is also discussed to demonstrate how the ontology supports pre-task planning in practice.

• Journal of the Korean Society of Clothing and Textiles
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• v.48 no.3
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• pp.397-416
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• 2024

This study investigated gender characteristics in contemporary virtual fashion design, focusing on avatars and genderless fashion in recent collections from Auroboros, Republiqe, Placebo Digital Fashion House, RTFKT, and Tribute. Employing content analysis within a theoretical framework of gender-related research, the study coded virtual avatars in terms of biological sex, appearance, and sociological perspectives. The results showed a preference for female-type avatars, through which androgynous aesthetics were embraced and traditional gender norms were challenged. Male-type avatars reflected experimentation with blending masculine elements, emphasizing inclusivity. Human-like avatars indicated a preference for designs that promoted inclusivity and, in the process, challenged binary classifications. The examined brands strategically capitalized on compromise, sensuality, and playfulness, thereby breaking away from traditional values to opt for more diverse styles. Genderless features combined elements from traditional men's and women's clothing, espousing sensuality and playful exaggeration. These findings signify a dynamic shift away from conventional gender standards to foster inclusivity and experimentation. They can serve as a reference for promoting creative strategies and design innovation, challenging the traditional gender perspective in the fashion industry. Implementing these strategies can lead to a more inclusive representation of fashion styles, encouraging critical thinking about gender norms.

• Structural Engineering and Mechanics
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• v.91 no.2
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• pp.227-238
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• 2024

Sparse regularization methods have proven effective in addressing the ill-posed equations encountered in moving force identification (MFI). However, the complexity of vehicle loads is often ignored in existing studies aiming at enhancing MFI accuracy. To tackle this issue, a double 𝑙₁ regularization method is proposed for MFI based on a response spectrum-based weighted dictionary in this study. Firstly, the relationship between vehicle-induced responses and moving vehicle loads (MVL) is established. The structural responses are then expanded in the frequency domain to obtain the prior knowledge related to MVL and to further construct a response spectrum-based weighted dictionary for MFI with a higher accuracy. Secondly, with the utilization of this weighted dictionary, a double 𝑙₁ regularization framework is presented for identifying the static and dynamic components of MVL by the alternating direction method of multipliers (ADMM) method successively. To assess the performance of the proposed method, two different types of MVL, such as composed of trigonometric functions and driven from a 1/4 bridge-vehicle model, are adopted to conduct numerical simulations. Furthermore, a series of MFI experimental verifications are carried out in laboratory. The results shows that the proposed method's higher accuracy and strong robustness to noises compared with other traditional regularization methods.

• International Area Studies Review
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• v.15 no.2
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• pp.331-350
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• 2011

This paper analyzes balance of goods for a panel data of 56 industry classification in the MTI from 1980 to 2009. This study also develops the equilibrium adjustment process, which is a trade-off between the adjustment costs towards equilibrium costs for balance of goods and the cost of being in disequilibrium. In this framework, the GMM estimation procedure is used to estimate this dynamic panel model consistently. It is found that equilibrium balances of goods in Korean adjust to the speed is very slow to 0.0389. because of this is necessary to adjust the equilibrium goods balance as the cost of goods balance deficit is larger than by the cost. In addition, the real income elasticity for goods balance of resin in Japan and Korea, the real income elasticity 4.38168 and -0.835225, respectively, the marks were consistent with economic theory. The exchange rate elasticity of goods balance in japan to 0.478435 were found in the inelastic.

• Geomechanics and Engineering
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• v.27 no.5
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• pp.465-479
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• 2021

One of the important causes of building and infrastructure failure, such as bridges on pile foundations, is the placement of the piles in liquefiable soil that can become unstable under seismic loads. Therefore, the overarching aim of this study is to investigate the seismic behavior of a soil-pile system in liquefiable soil using three-dimensional numerical FEM analysis, including soil-pile interaction. Effective parameters on concrete pile response, involving the pile diameter, pile length, soil type, and base acceleration, were considered in the framework of finite element non-linear dynamic analysis. The constitutive model of soil was considered as elasto-plastic kinematic-isotropic hardening. First, the finite element model was verified by comparing the variations on the pile response with the measured data from the centrifuge tests, and there was a strong agreement between the numerical and experimental results. Totally 64 non-linear time-history analyses were conducted, and the responses were investigated in terms of the lateral displacement of the pile, the effect of the base acceleration in the pile behavior, the bending moment distribution in the pile body, and the pore pressure. The numerical analysis results demonstrated that the relationship between the pile lateral displacement and the maximum base acceleration is non-linear. Furthermore, increasing the pile diameter results in an increase in the passive pressure of the soil. Also, piles with small and big diameters are subjected to yielding under bending and shear states, respectively. It is concluded that an effective stress-based ground response analysis should be conducted when there is a liquefaction condition in order to determine the maximum bending moment and shear force generated within the pile.

• Journal of KIISE:Information Networking
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• v.37 no.1
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• pp.72-83
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• 2010

Group communication in a wireless mesh network is complicated due to dynamic intermediate mesh points, access control for communications between different administrative domains, and the absence of a centralized network controller. Especially, many-to-many multicasting in a dynamic mesh network can be modeled by a decentralized framework where several subgroup managers control their members independently and coordinate the inter-subgroup communication. In this study, we propose a topology-matching decentralized group key management scheme that allows service providers to update and deliver their group keys to valid members even if the members are located in other network domains. The group keys of multicast services are delivered in a distributed manner using the identity-based encryption scheme. Identity-based encryption facilitates the dynamic changes of the intermediate relaying nodes as well as the group members efficiently. The analysis result indicates that the proposed scheme has the advantages of low rekeying cost and storage overhead for a member and a data relaying node in many-to-many multicast environment. The proposed scheme is best suited to the settings of a large-scale dynamic mesh network where there is no central network controller and lots of service providers control the access to their group communications independently.