• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.11
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• pp.4291-4310
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• 2015

This paper investigates the traffic offloading over unlicensed bands for two-tier multi-mode small cell networks. We formulate this problem as a Stackelberg game and apply a hierarchical learning framework to jointly maximize the utilities of both macro base station (MBS) and small base stations (SBSs). During the learning process, the MBS behaves as a leader and the SBSs are followers. A pricing mechanism is adopt by MBS and the price information is broadcasted to all SBSs by MBS firstly, then each SBS competes with other SBSs and takes its best response strategies to appropriately allocate the traffic load in licensed and unlicensed band in the sequel, taking the traffic flow payment charged by MBS into consideration. Then, we present a hierarchical Q-learning algorithm (HQL) to discover the Stackelberg equilibrium. Additionally, if some extra information can be obtained via feedback, we propose an improved hierarchical Q-learning algorithm (IHQL) to speed up the SBSs' learning process. Last but not the least, the convergence performance of the proposed two algorithms is analyzed. Numerical experiments are presented to validate the proposed schemes and show the effectiveness.

• KIISE Transactions on Computing Practices
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• v.21 no.9
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• pp.604-609
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• 2015

The use of Operating System(OS) virtualization is increasing as it provides many useful features such as efficient use of hardware(HW), easy system migration, and isolation between virtual spaces which prevents errors effecting each other. Recent development in HW has made it possible to use OS virtualization in embedded systems. However, implementing OS virtualization means that a multiple number of schedulers are layered in a system, rendering it difficult to analyze the schedulability of the system and errors are easily produced. Errors in safety critical embedded systems can cause serious damage to life and property; thus, the hierarchical schedulability must be verified. In this paper, we propose a framework which supports formal modeling and verification of hierarchical scheduling systems with UPPAAL.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.11
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• pp.3638-3657
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• 2022

In urban vehicular edge computing (VEC) environments, one edge server always serves many task requests in its coverage which results in the resource-constrained problem. To resolve the problem and improve system utilization, we first design a general hierarchical resource management framework based on typical VEC network structures. Following the framework, a specific interacting protocol is also designed for our decision algorithm. Secondly, a greedy bidding-based multi-hop task scheduling decision algorithm is proposed to realize effective task scheduling in resource-constrained VEC environments. In this algorithm, the goal of maximizing system utility is modeled as an optimization problem with the constraints of task deadlines and available computing resources. Then, an auction mechanism named greedy bidding is used to match task requests to edge servers in the case of multiple hops to maximize the system utility. Simulation results show that our proposal can maximize the number of tasks served in resource constrained VEC networks and improve the system utility.

• Journal of KIISE:Computer Systems and Theory
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• v.35 no.5
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• pp.187-198
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• 2008

This paper develops a framework for efficient resource management within the grid service environment. Resource management is the core element of the grid service; therefore, GridRMF(Grid Resource Management Framework) is modeled and developed in order to respond to such variable characteristics of resources as accordingly as possible. GridRMF uses the participation level of grid resource as a basis of its hierarchical management. This hierarchical management divides managing domains into two parts: VMS(Virtual Organization Management System) for virtual organization management and RMS(Resource Management System) for metadata management. VMS mediates resources according to optimal virtual organization selection mechanism, and responds to malfunctions of the virtual organization by LRM(Local Resource Manager) automatic recovery mechanism. RMS, on the other hand, responds to load balance and fault by applying resource status monitoring information into adaptive performance-based task allocation algorithm.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.6
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• pp.637-647
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• 2010

Recent embedded systems are being more complicated due to their hierarchical software architecture including operating systems. The performance of such complicated software architecture could not be well analyzed through separate analysis of each software layer; the combined effect and the interactions among the whole software layers should be considered. In this paper, we show the design and implementation of a performance analysis framework that enables hierarchical analysis of performance of Linux-based embedded systems considering interactions among the software layers. By using the proposed framework, we can obtain useful run-time information about a hierarchical software structure which usually consists of user-defined function layer, library function layer, system call layer, and kernel events layer. Experimental results reveal that the proposed framework could accurately identify the performance bottlenecks with the corresponding software layers during executions of target applications through the accompanying sub-steps of the analysis: the actual execution paths, the execution time of each observed event in each software layer, and the control flows across the software layers.

• Journal of Multimedia Information System
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• v.1 no.1
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• pp.55-67
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• 2014

Image topic and emotion analysis is an important component of online image retrieval, which nowadays has become very popular in the widely growing social media community. However, due to the gaps between images and texts, there is very limited work in literature to detect one image's Topics and Emotions in a unified framework, although topics and emotions are two levels of semantics that often work together to comprehensively describe one image. In this work, a unified model, Joint Topic/Emotion Multi-Modal Hierarchical Latent Dirichlet Allocation (JTE-MMHLDA) model, which extends previous LDA, mmLDA, and JST model to capture topic and emotion information at the same time from heterogeneous data, is proposed. Specifically, a two level graphical structured model is built to realize sharing topics and emotions among the whole document collection. The experimental results on a Flickr dataset indicate that the proposed model efficiently discovers images' topics and emotions, and significantly outperform the text-only system by 4.4%, vision-only system by 18.1% in topic detection, and outperforms the text-only system by 7.1%, vision-only system by 39.7% in emotion detection.

• Proceedings of the Korea Information Assurance Society Conference
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• 2004.05a
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• pp.199-204
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• 2004

Operating systems and application programs have security vulnerabilities derived from the software development process. Recently, incident cases related with the abuses of these vulnerabilities are increasing and the damages caused by them are becoming very important security issues all over the nations. Patch management is one of the most important processes to fix vulnerabilities of softwares and to ensure a security of systems. Since an institute or a company has distributed hierarchical and heterogeneous systems, it is not easy to update patches promptly. In this paper, we propose patch management framework to safely distribute and install the patches on Windows, Linux, and Solaris client systems. Besides, we censidered extensibility and hierarchical structure for our patch management framework to support large scaled network environment.

• Journal of Korea Game Society
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• v.8 no.1
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• pp.79-90
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• 2008

This paper describes a motivation-based hierarchical behavior planning framework to allow autonomous agents to select adaptive actions in simulation game environments. The combined behavior planning system is formed by four levels of specification, which are motivation extraction, goal list generation, action list determination and optimization. Our model increases the complexity of virtual human behavior planning by adding motivation with sudden and cumulative attributes. The motivation selection by probability distribution allows NPC to make multiple decisions in certain situations in order to embody realistic virtual humans. Hierarchical goal tree enhances the effective reactivity. Optimizing for potential actions provides NPC with safe and satisfying actions to adapt to the virtual environment. A restaurant simulation game was used to elucidate the mechanism of the framework.

• Journal of Korea Multimedia Society
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• v.12 no.1
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• pp.69-84
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• 2009

In this paper, a real-time web-casting framework for many individuals or small organizations imploring internet broadcasting, is designed and implemented. It is the purpose of the proposed framework that any individual can easily construct his own broadcast station if he has minimum facility for the content transmission to the framework. This type of system should have a flexible architecture to be applicable in wide variation of operational environment. Since the proposed framework follows a component-based hierarchical structure consisting of 3 types of components, it can effectively cope with change of internal or external operational environment by simple modification of the associated component with the change. Also, various types of target application systems in the aspects of cost and performance can be constructed in accordance with how to associate upper layer components with hardware platforms. A real prototype system based on the proposed framework is implemented, and then the response delay time is measured under varying number of content productions and content receivers. The results show that the response delay time follows M/M/1 model, which is one of the well-known performance models, and the implemented system may accommodate from 16 to 20 productions.

• Industrial Engineering and Management Systems
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• v.13 no.1
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• pp.15-28
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• 2014

Evaluation of the implementation and performance of a firm's green supply chain management (GSCM) is an ongoing process. Balanced scorecard is a multi-criteria evaluation concept that highlights implementation and performance measures. The literature on the framework is abundant literature but scarce on how to build a hierarchical framework under uncertainty with dependence relations. Hence, this study proposes a hybrid approach, which includes applied interpretive structural modeling to build a hierarchical structure and uses the analytic network process to analyze the dependence relations. Additionally, this study applies the fuzzy set theory to determine linguistic preferences. Twenty dependence criteria are evaluated for a GSCM implemented firm in Taiwan. The result shows that the financial aspect and life cycle assessment are the most important performance and weighted criteria.