• Journal of the Korea Society of Computer and Information
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• v.17 no.7
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• pp.107-115
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• 2012

Recently, Li and Hwang scheme proposed a biometrics-based remote user authentication scheme using smart card. It is asserted that this scheme has very excellent benefits by the operation cost efficiency based on the smart card, one-way function and biometrics using random numbers. But this scheme cannot provide the properly authentication, especially, it is analyzed as the vulnerable security scheme for Denial-of-Service(DoS) attacks by impersonate attacks. The attacker controls the insecure channel, they can easily fabricate messages to pass the user's or server's authentication, and the malicious attacker can impersonate the user to cheat the server and can impersonate the server to cheat the user without knowing any secret information. This paper proposes the strong improved scheme which can respond to multiple attacks by supplementing the function of integrity check from the server which applied variable authenticator and OSPA without exposing the user's password information. It is supplemented pregnable of disguise attack and mutual authentication of Li and Hwang scheme.

• Journal of Korea Spatial Information System Society
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• v.2 no.1 s.3
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• pp.5-16
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• 2000

OGC(Open GIS Consortium) suggests the 'OpenGIS Simple Feature Specification for CORBA' which is the OpenGIS implementation specification for CORBA to specify standard interfaces for reuse and interoperation among distributed heterogeneous GIS resources in the CORBA distributed computing environment. An OpenGIS server that supports this implementation specification moat correctly implement all interfaces defined in the OpenGIS implementation specification to be interoperable with wrapped GISs efficiently. In this paper, we have designed and implemented an OpenGIS server based an object relational GIS, called GEUS that integrates GIS and database technologies to provide spatial data types and spatial operators from the DBMS engine level. In the CORBA distributed computing environment, clients can access geospatial data stored in GIS wrapped by the OpenGIS server through the standard interfaces defined in the OpenGIS implementation specification for CORBA. In addition, clients can use geospatial operation features provided by a back-end GIS and interoperate with other GISs.

• The KIPS Transactions:PartA
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• v.19A no.2
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• pp.93-100
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• 2012

LLRP (Low-Level Reader Protocol) specifies an interface between RFID readers and RFID applications, also called LLRP servers and clients respectively. An LLRP server should concurrently execute various functions. This paper designs an LLRP server of a multi-threaded architecture. For that, (i) the operational procedure between LLRP servers and clients is investigated, (ii) the functional requirements of LLRP servers are presented, (iii) the operation of an LLRP server is decomposed into several threads to satisfy those functional requirements, and (iv) the operational procedure is further examined in thread-level. To validate the designed architecture, it is modeled and simulated by using the DEVS formalism which specifies discrete event systems in a hierarchical, modular manner. From the simulation result, we can conclude that the proposed architecture conforms the LLRP standard and satisfies all the given functional requirements.

• The Journal of the Korea Contents Association
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• v.5 no.2
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• pp.95-105
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• 2005

As a research on PKI is being very popular, the study relating to certificate status validation is being grown with aim to reduce an overhead of the protocol and to provide an efficient operation. The OCSP of the standard protocol related to the study enables applications to determine the revocation state of an identified certificate. However, the OCSP server can not service millions of certificate status validation requests from clients in a second on E-commerce because of the computational time for signature and verification. So, we propose the Real-time Certificate Status Validation Protocol(RCSVP) that has smaller computational time than OCSP. RCSVP server reduce the computational time of certificate status validation using hash function and common secret value. Also RCSVP client does not need the computational time of certificate verification to acquire the public key from an identified certificate. Therefore, the proposed protocol enables server to response millions of certificate status validation requests from clients in a second on E-commerce.

• Journal of KIISE:Databases
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• v.31 no.4
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• pp.422-431
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• 2004

In recent years, different models in data delivery have been explored in mobile computing systems. Particularly, there were a lot of research efforts in the periodic push model where the server repetitively disseminates information without explicit request. However, average waiting time per data operation highly depends on the length of a broadcast cycle and different access pattern among clients may deteriorate the response time considerably. In this case, clients are preferably willing to send a data request to the server explicitly through backchannel in order to obtain optimal response time. We call the broadcast model supporting backchannel as hybrid broadcast. In this paper, we devise a new transaction processing algorithm(O-PreH) in hybrid broadcast environments. The data objects which the server maintains are divided into Push_Data for periodic broadcasting and Pull_Data for on-demand processing. Clients tune in broadcast channel or demand the data of interests according to the data type. Periodic invalidation reports from the server support maintaining transactional consistency. If one or more conflicts are found, conflict orders are determined not to violate the consistency(pre-reordering) and then the remaining operations have to be executed pessimistically. Through extensive simulations, we demonstrate the improved throughput of the proposed algorithm.

• Journal of the Korea Society for Simulation
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• v.25 no.3
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• pp.117-123
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• 2016

This paper presents inference methods for inner operations of a multi-server queue when historical data are limited or system observation is restricted. In a queueing system analysis, autocorrelated arrival and service processes increase the complexity of modeling. Accordingly, numerous analysis methods have been developed. In this paper, we introduce an inference method for specific situations when external observations exhibit autocorrelated structure and and observations of internal operations are difficult. We release an assumption of the previous method and provide lemma and theorem to guarantee the correctness of our proposed inference method. Using only external observations, our proposed method deduces the internal operation of a multi-server queue via non-parametric approach even when the service times are autocorrelated. The main internal inference measures are waiting times and service times of respective customers. We provide some numerical results to verify that our method performs as intended.

• Journal of Convergence for Information Technology
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• v.9 no.1
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• pp.19-27
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• 2019

In recent years, with the advancement of IT technology, we expect data size of the world to increase 10 times in 2025. The rapid development of this Internet technology leads to the downsizing of the server system of the data center which manages and operates the data, the capacity of the storage medium, and the power consumption of the data center. In this paper, we propose an energy conservation policy and analyze it in real time by analyzing the power consumption pattern of the server system of the data center. The proposed system can monitor and analyze the power consumption pattern of the individual server system in the data center, and it can be expected that about 10% of the total power consumption of the data center will be saved by efficiently managing the actual operation time of the server system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.889-890
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• 2016

Existing machine-to-machine collaboration system is a centralized structure system fo built OpenWrt and a Web server on the router. But scarce resources of the router are getting more requests from the collaboration client when a problem has occurred with increasing probability of a client object, the higher the traffic. In this paper, in order to solve the problem, we propose a distributed system utilizing Machine Socialization cooperation algorithm. The MCU attached to the machine to minimize the traffic occurrence probability and loss of the data by processing to distribute the data between the server and the client. Also improve the response speed between the server and the client and the operation stop caused by the loss of data. The proposed system will be utilized if the IoT field will be high efficiency compared to existing systems.

• Nuclear Engineering and Technology
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• v.54 no.8
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• pp.2852-2858
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• 2022

A proton therapy facility is under development at Huazhong University of Science and Technology (HUST). To meet the need for fast energy changes during treatments, a beamline control system (BCS) has been designed and implemented. The BCS coordinates and controls various beamline devices by adopting a distributed architecture divided into three layers: the client, server, and device layers. Among these, the design of the server layer is the key to realize fast energy changes. The server layer adopts the submodule programming paradigm and optimizes the data interface among modules, allowing the main workflow to be separated from the device workflow and data. Furthermore, this layer uses asynchronous, multithreaded, and thread-locking methods to improve the system's ability to operation efficiently and securely. Notably, to evaluate the changing energy status over time, a dynamic node update method is adopted, which can dynamically adjust the update frequency of variable nodes. This method not only meets the demand for fast updates on energy changes but also reduces the server's communication load in the steady state. This method is tested on a virtual platform, and the results are as expected.

• Journal of Advanced Technology Convergence
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• v.2 no.3
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• pp.9-15
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• 2023

Recently, various public services are being performed based on information systems as the informatization business spreads. Public administration services based on these information systems provide internal and external services. In recent years, as the construction of cloud-based public services has been expanded, the advancement of information systems has attracted attention. In particular, as the dependence on information systems increases, the establishment of a response system to prevent dangerous situations such as interruption and paralysis of information systems in advance has become a hot topic not only in companies but also in public institutions. Therefore, in this paper, a disaster recovery system was designed and built to maximize the efficiency of system operation and shorten recovery time through service conversion automation of the disaster recovery system. The integrated DR server redundancy test, web server redundancy test, FC-IP redundancy test, and SAN switch redundancy test were performed respectively by applying the disaster recovery system designed and built according to the method proposed in the paper.