• Proceedings of the Korean Operations and Management Science Society Conference
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• 2004.05a
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• pp.441-445
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• 2004

In this paper, we deal with an inventory model of a multi-stage, serial supply chain system where a single product type and nonstationary customer demand pattern are considered. The retailer and suppliers place their orders according to an echelon-stock based replenishment control policy. We assume that the suppliers can access online information on the demand history and use this information when making their replenishment decisions. Using a reinforcement learning technique, the inventory control parameters are designed to adaptively change as the customer demand pattern is altered, in order to maintain a given target service level. Through a simulation based experiment, we verified that our approach is good for maintaining the target service level.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.10
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• pp.4823-4843
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• 2017

In this paper, an improved utility-based cross-layer dynamic subcarrier allocation (DSA) algorithm is proposed for single carrier frequency division multiple access (SC-FDMA) system, which adopts adaptive service rate control (ASRC) to eliminate the service rate waste and improve the spectral efficiency in heterogeneous network including non-real-time traffic and real-time traffic. In this algorithm, furthermore, a first in first out (FIFO) queuing model with finite space is established on the cross-layer scheduling framework. Simulation results indicate that by taking the service rate constraint as the necessary condition for optimality, the ASRC algorithm can effectively eliminate the service rate waste without compromising the scheduling performance. Moreover, the ASRC algorithm is able to further improve the quality of service (QoS) performance and transmission throughput by contributing an attractive performance trade-off between real-time and non-real-time applications.

• Journal of Information Processing Systems
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• v.1 no.1 s.1
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• pp.86-95
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• 2005

Location-based services or LBS refer to value-added service by processing information utilizing mobile user location. With the rapidly increasing wireless Internet subscribers and world LBS market, the various location based applications are introduced such as buddy finder, proximity and security services. As the killer application of the wireless Internet, the LBS have reconsidered technology about location determination technology, LBS middleware server for various application, and diverse contents processing technology. However, there are fears that this new wealth of personal location information will lead to new security risks, to the invasion of the privacy of people and organizations. This paper describes a novel security approach on open LBS service to validate certificate based on current LBS platform environment using XKMS (XML Key Management Specification) and SAML (Security Assertion Markup Language), XACML (extensible Access Control Markup Language) in XML security mechanism.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.4
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• pp.167-174
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• 2008

As both a digital camera and a digital camcorder are popularized in recent years, UCC created by general users is also popularized. Unfortunately, according to that, the lack of privacy is also increasing more and more. The UCC is saved on the recordable media(Media) like DVD and deposited personally as well as distributed through Internet portal service. If you use Internet portal service to put up your contents, you can partially prevent the violation of privacy using security technologies such as authentication and illegal copy protection offered by internet portal service providers. Media also has technologies to control illegal copy. However, it is difficult to protect your privacy if your Media having personal contents is stolen or lost. Therefore, it is necessary to develope an additional security mechanism to guarantee privacy protection when you use Media. In this paper, we describe AACS framework for Media Security and propose improved AACS framework to control the access to personal contents saved on Media.

• Proceedings of the Korea Society for Simulation Conference
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• 2005.05a
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• pp.29-33
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• 2005

Grid computing is widely applicable to various fields of industry including process control and manufacturing, military command and control, transportation management, and so on. In a viewpoint of application area, grid computing can be classified to three aspects that are computational grid, data grid and access grid. This paper focuses on computational grid which handles complex and large-scale computing problems. Computational grid is characterized by system dynamics which handles a variety of processors and jobs on continuous time. To solve problems of system complexity and reliability due to complex system dynamics, computational grid needs scheduling policies that allocate various jobs to proper processors and decide processing orders of allocated jobs. This paper proposes the service prediction-based job scheduling model and present its algorithm that is applicable for computational grid. The service prediction-based job scheduling model can minimize overall system execution time since the model predicts a processing time of each processing component and distributes a job to processing component with minimum processing time. This paper implements the job scheduling model on the DEVSJAVA modeling and simulation environment and simulates with a case study to evaluate its efficiency and reliability Empirical results, which are compared to the conventional scheduling policies such as the random scheduling and the round-robin scheduling, show the usefulness of service prediction-based job scheduling.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.12B
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• pp.1623-1635
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• 2011

Fourth-generation (4G) cellular communication systems must provide different quality-of-service (QoS) to users according to the service type, membership class, and usage case of each user. For the purpose of user's QoS differentiation, we propose an enhanced uplink random access scheme for bandwidth request. More specifically, we divide a bandwidth request channel into two parts: One is a primary region and the other is a secondary region. Then, each region has a unique minimum access class that allows only specific users to perform random access through that region. By doing so, we can reduce collision probability and increase the success probability of bandwidth request. From the perspective of standardization, we presented this scheme in the IEEE 802.16m Session #66 held on March 2010. As a result, the concept of the proposed scheme and required messages were defined in the 802.16m standard.

• Journal of the Korea Convergence Society
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• v.1 no.1
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• pp.23-29
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• 2010

The various kinds of application is distributed for the Smart phone user recently. There is the advantage that the open source application on Android operating system based Smart phone supports a multi tasking service. Layar, Wikitude, and Sherpa and the other applications using the GPS location information like an a2b etc. were developed in the Smart phone environment. However, the existing Cell-ID based location information can be directly collected by the mobile ISP unit which the mobile carrier installs, the personal privacy problem occurs. Therefore, the personal location information is possible to be exposed publicly without any access control procedure. Therefore, in this research, the self-control mechanism on the GPS location information at the Smart phone is designed and presented. Through this, it is possible to develop diverse applications providing enhanced access control and GPS location management on the Android based Smart Phone.

• Journal of KIISE:Computer Systems and Theory
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• v.35 no.9_10
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• pp.452-465
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• 2008

This paper proposes a light-weight, seamless integrated access control for global e-Science resource sharing. E-Science, based on Grid Computing, was designed to help scientists to remotely control and process the Grid resources such as high-end equipments and remote machines. As many researchers engage in the e-Science Grids, the researchers in a grid often have to wait for or give up use of the Grid resources, even when there are idle resources in other Grids. In this case, provided that proper compensation is given, Grid resource sharing is helpful both for the researchers and the Grids which provide their resources. But, sharing Grid resources globally is not simple, as each e-Science Grid is especially designed for resource sharing in its Virtual Organization(VO) and already has its unique access control policy for its resources. This paper proposes a new integrated access control for e-Science Grid resource sharing. The access control is light-weight without any priori service level agreement(SLA)s among the Grids which share their resources and seamless because the users can use the resources shared as the ones belonging to their Grids without their additional registration to the other Grids.

• Journal of KIISE:Software and Applications
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• v.34 no.3
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• pp.219-225
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• 2007

UPnP AV Framework automatically integrates and manages various AV devices that are connected to network as an important component in home network. Therefore, user can access and control AV contents at any time. But, other existing home entertainment systems target multimedia service support that is based on multimedia home server system. In this paper, we propose an integrated home entertainment system (u-MUSE system) that supports remote control service. It can manage application in remote AV device or control AV contents directly in home network environment. The proposed system sufficiently performs role of control center for electronic devices in home via integrated system control and AV contents playback service.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.535-538
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• 2005

Wireless LANs based on the IEEE 802.11 standard are widely spread for use nowadays. Traffic which are conveyed over the WLANs change rapidly from normal data such a Email and Web pages, to multimedia data of high resolution video and voice. To meet QoS (Quality of Service) required by these multimedia traffic, the IEEE 802 committee recently has developed a new standard, IEEE 802.11e. IEEe 802.11.e contains two MAC mechanisms for providing QoS: EDCA(Enhanced Distributed Channel Access) and HCCA (HCF Controlled Channel Access). Using these standardized MAC mechanisms as a building platform, various admission control mechanisms can be combined to offer QoS gurantees for multimedia traffic. This paper surveys these research efforts.