• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.11
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• pp.5323-5343
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• 2018

Mobile applications and social networks tend to enhance the need for high-quality content access. To address the rapid growing demand for data services in mobile networks, it is necessary to develop efficient content caching and distribution techniques, aiming at significantly reduction of redundant content transmission and thus improve content delivery efficiency. In this article, we develop optimal cooperative content cache and distribution policy, where a geographical cluster model is designed for content retrieval across the collaborative small cell base stations (SBSs) and replacement of cache framework. Furthermore, we divide the SBS storage space into two equal parts: the first is local, the other is global content cache. We propose an algorithm to minimize the content caching delay, transmission cost and backhaul bottleneck at the edge of networks. Simulation results indicates that the proposed neighbor SBSs cooperative caching scheme brings a substantial improvement regarding content availability and cache storage capacity at the edge of networks in comparison with the current conventional cache placement approaches.

• ETRI Journal
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• v.43 no.1
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• pp.53-63
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• 2021

Cloud computing has drastically reduced the price of computing resources through the use of virtualized resources that are shared among users. However, the established large cloud data centers have a large carbon footprint owing to their excessive power consumption. Inefficiency in resource utilization and power consumption results in the low fiscal gain of service providers. Therefore, data centers should adopt an effective resource-management approach. In this paper, we present a novel load-balancing framework with the objective of minimizing the operational cost of data centers through improved resource utilization. The framework utilizes a modified genetic algorithm for realizing the optimal allocation of virtual machines (VMs) over physical machines. The experimental results demonstrate that the proposed framework improves the resource utilization by up to 45.21%, 84.49%, 119.93%, and 113.96% over a recent and three other standard heuristics-based VM placement approaches.

• Journal of the Korean Academy of Esthetic Dentistry
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• v.16 no.2
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• pp.7-18
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• 2007

There is now an increased demand for harmony between the peri-implant gingiva and adjacent dentition. In the event of a pending loss of a single tooth in the aesthetic zone with healthy periodontium, expectation for optimal gingival and prosthodontic aesthetics are often very high. Unfortunately, bone resorption is common following the removal of an anterior tooth, compromising the gingival tissue levels for the eventual implant restoration. Also, improper implant placement and inadequate osseous-gingival support potentially deleterious aesthetic result. The creation of an esthetic implant restoration with gingival architecture that harmonizes with the adjacent dentitionis formidable challenge. The predictability of the peri-implant esthetic outcome may ultimately be determined by the patient's own presenting anatomy rather than the clinician's ability to manage state-of-the-art procedures. To more accurately predict the peri-implant esthetic outcome before removing a failing tooth, a considering of diagnostic keys is essential. This presentation addresses the useful diagnostic keys that affect the predictability of peri-implant gingival aesthetics and the overcoming of the risk factors in anterior single-tooth replacement; it also describes a surgical and prosthodontic technique in achieving a long term successful esthetic outcome. Proper diagnosis and understanding of the biological and periodontal variables of failing dentition and their response to surgical and prosthodontic procedures are the essence of predictability. Using a smart protocol that alters the periodontium toward less risk and more favorable assessment of the diagnostic keys before implant placement will provide the most predictable esthetic outcome. Simple diagnostic keys suggested this presentation are useful method to evaluate the overcoming of the risk factors in anterior single implant restoration.

• Journal of the Earthquake Engineering Society of Korea
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• v.8 no.5 s.39
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• pp.55-64
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• 2004

In this paper, the preliminary design procedure of magnetorheological (MR) dampers is developed for controlling the building response induced by seismic excitation. The dynamic characteristics and control effects of the modeling methods of MR dampers such as Bingham, biviscous, hysteretic biviscous, simple Bouc?Wen, Bouc?Wen with mass element, and phenomenological models are investigated. Of these models, hysteretic biviscous model which is simple and capable describing the hysteretic characteristics, is used for numerical studies. The capacity of MR damper is determined as a portion of not the building weight but the lateral restoring force. A method is proposed for optimal placement and number of MR dampers, and its effectiveness is verified by comparing it with the simplified sequential search algorithm. Numerical results indicate that the capacity, number and the placement can be reasonably determined using the proposed design procedure.

• Smart Structures and Systems
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• v.14 no.1
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• pp.39-54
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• 2014

Node layout optimization of structural wireless systems is investigated as a means to prolong the network lifetime without, if possible, compromising information quality of the measurement data. The trade-off between these antagonistic objectives is studied within a multi-objective layout optimization framework. A Genetic Algorithm is adopted to obtain a set of Pareto-optimal solutions from which the end user can select the final layout. The information quality of the measurement data collected from a heterogeneous WSN is quantified from the placement quality indicators of strain and acceleration sensors. The network lifetime or equivalently the network energy consumption is estimated through WSN simulation that provides realistic results by capturing the dynamics of the wireless communication protocols. A layout optimization study of a monitoring system on the Great Belt Bridge is conducted to evaluate the proposed approach. The placement quality of strain gauges and accelerometers is obtained as a ratio of the Modal Clarity Index and Mode Shape Expansion values that are computed from a Finite Element model of the monitored bridge. To estimate the energy consumption of the WSN platform in a realistic scenario, we use a discrete-event simulator with stochastic communication models. Finally, we compare the optimization results with those obtained in a previous work where the network energy consumption is obtained via deterministic communication models.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.6
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• pp.778-785
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• 2020

Wireless mesh networks consist of mesh clients, mesh routers and mesh access points. The mesh router connects wireless network services to the mesh client, and the mesh access point connects to the backbone network using a wired link and provides Internet access to the mesh client. In this paper, a limited number of mesh routers and mesh access points are used to propose optimization algorithms for network design for wireless mesh networks. The optimization algorithm in this paper has been applied with a sub-subscription algorithm, which is one of the meta-heuristic methods, and is designed to minimize the transmission delay for the placement of mesh routers and mesh access points, and produce optimal results within a reasonable time. The proposed algorithm was evaluated in terms of transmission delay and time to perform the algorithm for the placement of mesh routers and mesh access points, and the performance evaluation results showed superior performance compared to the previous meta-heuristic methods.

• Journal of the Korea Institute of Building Construction
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• v.23 no.6
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• pp.863-873
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• 2023

This research explores the efficacy of safety vest colors at construction sites to enhance worker safety. Utilizing the Munsell color system and the Korean Standard Color Analysis program(KSCA), the study developed a prototype safety vest tailored to specific types of construction work. A safety vest with a color contrasting the site's environment significantly improves worker visibility and intuitiveness in identification, potentially reducing safety incidents. The study determined the optimal color specifications(hue, value, chroma) for safety vests in various construction roles, such as 10GY, 8, 8 for rebar placement, 8.75B, 7, 8 for Euroform, 3.75B, 2, 4 for Gangform, and 6.25BG, 5, 10 for steel erection. Feedback from construction experts on these prototypes, particularly regarding the safety vests for rebar placement and steel framework, was overwhelmingly positive(90% approval). Consequently, the proposed safety vest color scheme is deemed highly effective.

• International Journal of Computer Science & Network Security
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• v.21 no.12
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• pp.248-256
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• 2021

Now that we're in the big data era, data has taken on a new significance as the storage capacity has exploded from trillion bytes to petabytes at breakneck pace. As the use of cloud computing expands and becomes more commonly accepted, several businesses and institutions are opting to store their requests and data there. Cloud storage's concept of a nearly infinite storage resource pool makes data storage and access scalable and readily available. The majority of them, on the other hand, favour a single cloud because of the simplicity and inexpensive storage costs it offers in the near run. Cloud-based data storage, on the other hand, has concerns such as vendor lock-in, privacy leakage and unavailability. With geographically dispersed cloud storage providers, multicloud storage can alleviate these dangers. One of the key challenges in this storage system is to arrange user data in a cost-effective and high-availability manner. A multicloud storage architecture is given in this study. Next, a multi-objective optimization problem is defined to minimise total costs and maximise data availability at the same time, which can be solved using a technique based on the non-dominated sorting genetic algorithm II (NSGA-II) and obtain a set of non-dominated solutions known as the Pareto-optimal set.. When consumers can't pick from the Pareto-optimal set directly, a method based on Principal Component Analysis (PCA) is presented to find the best answer. To sum it all up, thorough tests based on a variety of real-world cloud storage scenarios have proven that the proposed method performs as expected.

• Journal of Digital Convergence
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• v.17 no.7
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• pp.59-71
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• 2019

The distribution logistics center has its own inventory, so designing an efficient storage area is very important. The purpose of this study is to present the optimal storage area calculation method for distribution logistics center considering the use of standard pallet unit load, and the results of this study are as follows. First, standard rack modules for storing T-11 and T-12 type pallet, which is generally used in Korea, were defined. Second, a variety of pallet transport equipments were investigated and analyzed to define the standard transport equipment's work passageway by type. Finally, it has great implications in terms of suggesting measures to minimize unused space that may occur during placement of pallet rack modules within storage space, as well as the easy and optimal calculation of the storage area for the distribution logistics center. Future research require a study on the layout of the entire distribution logistics center, which reflects the latest logistics technologies, such as standard rack modules for Mini-Load and GTP picking system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.5
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• pp.786-792
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• 2022

In the cloud computing environment, there has been a lot of research into the Fog/Edge Computing (FEC) paradigm for securing user proximity of application services and computation offloading to alleviate service delay difficulties. The method of predicting dynamic location change patterns of edge devices (moving objects) requesting application services is critical in this FEC environment for efficient computing resource distribution and deployment. This paper proposes an optimal moving pattern extraction algorithm in which variable weights (distance, time, congestion) are applied to selected paths in addition to a support factor threshold for frequency patterns (moving objects) of edge devices. The proposed algorithm is compared to the OPE_freq [8] algorithm, which just applies frequency, as well as the A^* and Dijkstra algorithms, and it can be shown that the execution time and number of nodes accessed are reduced, and a more accurate path is extracted through experiments.