• Journal of Information Processing Systems
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• v.16 no.1
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• pp.96-112
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• 2020

Solving the disclosure problem of sensitive information with the k-nearest neighbor query, location dummy technique, or interfering data in location-based services (LBSs) is a new research topic. Although they reduced security threats, previous studies will be ineffective in the case of sparse users or K-successive privacy, and additional calculations will deteriorate the performance of LBS application systems. Therefore, a model is proposed herein, which is based on geohash-encoding technology instead of latitude and longitude, memcached server cluster, encryption and decryption, and authentication. Simulation results based on PHP and MySQL show that the model offers approximately 10× speedup over the conventional approach. Two problems are solved using the model: sensitive information in LBS application is not disclosed, and the relationship between an individual and a track is not leaked.

• The Transactions of the Korea Information Processing Society
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• v.7 no.3
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• pp.953-961
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• 2000

In this paper, we propose the algorithm which solve synchronization problem happened migrating service objects. Load imbalance is occurred due to allocate different amount of load to be proposed to each node in distribute system. To solve this problem, the service objects have to be migrated from heavily loaded node to lightly loaded node. And in such a process, the synchronization problem may occur when client request a service object migrated incompletely. Therefore, we describe the environment of executing service objects, the importer/exporter/trader model compatible with migration of service objects, and appropriate migration algorithm, Finally, we analyze the conditions of problems, and propose the solution of each situations. Also, the performance advantages of using proposed algorithms are quantified through a simulation study.

• Journal of KIISE:Information Networking
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• v.30 no.3
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• pp.387-396
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• 2003

In this paper, we present more efficient Protocol than that of Ford and Kaliski. We use RSA in the roaming protocol and it Plays decisive role to reduce the total time cost. We show that our protocol is safe from various attacks. We present the performance of our protocol and verify that This protocol needs fewer secure channel like SSL than other protocols.

• The KIPS Transactions:PartA
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• v.13A no.4 s.101
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• pp.323-334
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• 2006

A metadata service is one of the important factors to affect the performance of cluster file systems. We propose a content-based load balancing algorithm that dynamically distributes client requests to appropriate metadata servers based on the types of metadata operations. By replicating metadatas and logging update messages in each server, rather than moving metadatas across servers, we significantly reduced the response time and evenly distributed client's requests among metadata servers.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.3
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• pp.59-65
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• 2004

The paper presents a small unmanned probing ship that can be used for acquiring information on marine and coastal environments. For communication system, we adopt direct and indirect methods based on the wireless modem of a commercial cellular telephone. The former is a direct communication between the modems of the ship and the server, and the latter is an indirect communication via internet between the ship and the server. The system is equipped with a digital compass and a GPS for position estimation, and extended Kalman filter is used for Navigation. The performance of the ship is demonstrated with the results produced by sets of experiments.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.12
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• pp.2226-2231
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• 2008

As the mobile devices and the wireless networks have high-performance capabilities, it is possible to synchronize the spatio-temporal data of a server with the spatio-temporal data of a mobile device which are collected at a field. However, since the server process the synchronization which the model device requests, the whole synchronizations of mass mobile devices take long time. In this paper, we propose the scheme to process concurrently the synchronizations of mobile devices to use multi-queue which does not conflict.

• Journal of the Korea Society of Computer and Information
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• v.24 no.7
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• pp.1-8
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• 2019

Recently, an SSD with hybrid buffer memories is actively researching to reduce the overall latency in server computing systems. However, existing hybrid buffer policies caused many swapping operations in pages because it did not consider the overall latency such as read/write operations of flash chips in the SSD. This paper proposes the clock with hybrid buffer memories (CLOCK-HBM) for a new hybrid buffer policy in the SSD with server computing systems. The CLOCK-HBM constructs new policies based on unique characteristics in both DRAM buffer and NVMs buffer for reducing the number of swapping operations in the SSD. In experimental results, the CLOCK-HBM reduced the number of swapping operations in the SSD by 43.5% on average, compared with LRU, CLOCK, and CLOCK-DNV.

• 한국HCI학회:학술대회논문집
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• 2008.02b
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• pp.103-108
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• 2008

Art is an ongoing process of experimenting and challenging. The challenge and experiments of the artists encompass both the conceptual process and the expressive process of creating artworks. It is not mandatory to use cutting-edge technologies for interactive performances, since they can be realized by adapting pre-existing technologies. Using previous technologies reduces the difficulties in the production process and makes it easier for the audience to understand the way of participation. In this paper, propose an ARS-server-based control system in which a large audience can participate during a performance to control certain features on stage. This system was first proposed during the 'Ubiplay Workshop and Seminar' hosted by the GSCT, KAIST, and applied to the digital performance 'Syntasia' in June and July, 2007, hosted by the Goyang Culture Foundation.

• The Journal of Korean Association of Computer Education
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• v.4 no.1
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• pp.77-85
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• 2001

The virtual education has extended its position as a new educational mean in the whole society. A lot of cyber campuses like the virtual training institutes and the remote colleges were newly formed. With the development of the technology related to the Internet, new systems that support smooth virtual education have appeared. But the systems that had no problems at first became low speed gradually with the increase of the learners and contents and there arose a lot of problems. The problems can be solved through upgrading the hardware equipments, but it needs a lot of expenses and there always exists waste of unnecessary system resources. Accordingly, this study is to test the performance of the server through the simulation under various situations and investigate the plan for improvement in order to grope for the plan that can improve the performance of the virtual education systems. It is fragmentary simulation. But if we would like to correct the server programs and complement it on the basis of these plans for improvement, we may expect the sufficient improvement of performance. Also it may have sufficient values as data for smooth virtual education.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.35C no.6
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• pp.9-19
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• 1998

RAID technology that provides the disk I/O system with high performance and high availability is essential for OLTP server. This paper describes the design and implementation of the HIPSS RAID system that has been developed for the SPAX OLTP server. HIPSS has the following design objectives: high performance, high availability, standardization and modularization of external interface, and ease of maintenance. It guarantees high performance by providing 10 independent I/O channels, large data cache, and parity calculation engine. Hardware modularization of the host interface makes it easy to replace host interface hardware module. By providing dual power supply, dual array controller, and disk hot swapping, it provides the system with high availability Implementation of HIPSS and integration test on SPAX has been completed and performance measurement on HIPSS is now going on. In this paper, we provide the detail description for HIPSS system architecture and the implementation results.