• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.10
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• pp.1123-1130
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• 2015

Network on a chip(NoC) is a communication subsystem between intellectual property(IP) cores in a SoC and improves high performance in the scalability and the power efficiency compared with conventional buses and crossbar switches. NoC needs a synchronizer to overcome the metastability problem between data links. This paper presents a new mesochronous synchronizer(MS) which is composed of selection window generator, selection signal generator, and data buffer. A delay line circuit is used to build selection window in selection window generator based on the delayed clock cycle of transmitted clock and the transmitted clock is compared with local clock to generate a selection signal in the SW(selection window). This MS gets rid of the restriction of metastability by choosing a rising edge or a falling edge of local clock according to the value of selection signal. The simulation results show that the proposed MS operates correctly for all phase differences between a transmitted clock and a local clock.

• Journal of Korea Multimedia Society
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• v.9 no.7
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• pp.827-834
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• 2006

In distributed virtual environment, system response time to users' interactions is an importance factor to determine the degree of contentment with the system. Generally, response time is affected by the efficiency of event message processing algorithm, and most of previous systems use FCFS algorithm, which processes message traffic sequentially based only on the event occurrence time. Since this method totally depends on the order of occurrence without considering the priorities of events, it has a problem that might drop the degree of system response time by causing to delay processing message traffic when a bottleneck phenomenon happens in the server side. To overcome this limitation of FCFS algorithm, this paper proposes a concurrent event scheduling algorithm, which is able to process event messages concurrently by assigning the priorities to the events. It is also able to satisfy the two goals of system together, consistency and responsiveness through the combination of occurrence time with priority concept of events.

• Proceedings of the Korea Society of Information Technology Applications Conference
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• 2005.11a
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• pp.165-168
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• 2005

The objects, which can be personal digital assistants, electronic rings, doors or even clothes, offer embedded chips with computation facilities and are generally called artifacts. I later realized that this was not so the real problem is actually authentication. Recent results indicate scalability problems for flat ad hoc networks. Sensor network achieves function that handle surrounding information perception through sensor and sensed information to network that is consisted of sensor nodes of large number. Research about new access control techniques and height administration techniques need authentication information persons' certification assurance level classification in sensor network environment which become necessary different view base with authentication information at node for application of AAA technology in USN environment that must do authentication process using information that is collected from various sensor mountings. So, get base authentication information in sensor type and present weight grant model by security strength about authentication information through information who draw. In this paper collected information of sensor nodes model who give weight drawing security reinforcement as authentication information by purpose present be going to. and Must be able to can grasp special quality of each sensor appliances in various side and use this and decide authentication assurance level for value estimation as authentication information elements. Therefore, do to define item that can evaluate Authentication information elements thus and give simple authentication assurance level value accordingly because applying weight. Present model who give authentication assurance level value and weight for quotation according to security strength.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.5
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• pp.715-721
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• 2018

With the spread of mobile devices, the users of social network services or e-commerce sites have increased dramatically, and the amount of data produced by the users has increased exponentially. E-commerce companies have faced a task regarding how to extract useful information from a vast amount of data produced by the users. To solve this problem, there are various studies applying big data processing technique. In this paper, we propose a collaborative filtering method that applies the tag weight in the Apache Spark platform. In order to elevate the accuracy of recommendation, the proposed method refines the tag data in the preprocessing process and categorizes the items and then applies the information of periods and tag weight to the estimate rating of the items. After generating RDD, we calculate item similarity and prediction values and recommend items to users. The experiment result indicated that the proposed method process large amounts of data quickly and improve the appropriateness of recommendation better.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.2
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• pp.676-682
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• 2018

As the IoT world including WSNs develops, the number of sensor systems that sense information according to the environment based on the principle of IoT is increasing. In order to perform security for each sensor system in such a complicated environment, the security modules must be varied. These problems make hardware/software implementation difficult when considering the system efficiency and hacking/cracking. Therefore, to solve this problem, this paper proposes a pseudorandom number generator (FLT: Pseudo-random Number Generator with Fixed Length Tap unrelated to the variable sensing nodes) with a fixed-length tap that generates a pseudorandom number with a constant period, irrespective of the number of sensing nodes, and has the purpose of detecting anomalies. The proposed FLT-LFSR architecture allows the security level and overall data formatting to be kept constant for hardware/software implementations in an IoT environment. Therefore, the proposed FLT-LFSR architecture emphasizes the scalability of the network, regardless of the ease of implementation of the sensor system and the number of sensing nodes.

• KIISE Transactions on Computing Practices
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• v.22 no.6
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• pp.296-301
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• 2016

Object-based storage is an efficient storage solution that can handle unstructured data and shows better security and scalability than traditional block-based storage. However, in terms of power management, Object-based storage writes multiple copies in storage cluster, hence many servers consume unnecessary power in idle state. In order to resolve this problem, it is necessary to apply power management strategy by adjusting power mode of servers in idle state according to their workloads. In this paper, we proposed a new dynamic power management (DPM) method to transform power mode of storage servers dynamically according to workload information sent from proxy server. The experimental result shows that the proposed power management technic reduces total power consumption by 12% in the OpenStack based Swift object storage.

• The Journal of the Korea Contents Association
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• v.10 no.6
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• pp.91-105
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• 2010

A wireless sensor network communication technique has been broadly studied with continuous advances in ubiquitous computing environment. Especially, because the resource of the sensor node is limited, it is important to reduce the communication energy by using an energy-efficient routing protocol. The existing cluster-based routing protocols have a problem that they cannot select a cluster head efficiently by randomly choosing a head. In addition, because the existing cluster-based routing protocols do not support the large scale of network, they cannot be used for various applications. To solve the above problems, we, in this paper, propose a new cluster-based routing protocol using representative paths. The proposed protocol constructs an efficient cluster with distributed cluster heads by creating representative paths based on hop count. In addition, a new routing protocol supports multi-hop routing for data communication between a cluster member node and a cluster head as well as between cluster heads. Finally, we show that our protocol outperforms LEACH and Multihop-LEACH in terms of reliability and scalability.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.68-73
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• 2005

Various techniques have been proposed for detection and tracking of targets in order to develop a real-world computer vision system, e.g., visual surveillance systems, intelligent transport systems (ITSs), and so forth. Especially, the idea of distributed vision system is required to realize these techniques in a wide-spread area. In this paper, we develop a ubiquitous vision system for location-awareness of multiple targets. Here, each vision sensor that the system is composed of can perform exact segmentation for a target by color and motion information, and visual tracking for multiple targets in real-time. We construct the ubiquitous vision system as the multiagent system by regarding each vision sensor as the agent (the vision agent). Therefore, we solve matching problem for the identity of a target as handover by protocol-based approach. We propose the identified contract net (ICN) protocol for the approach. The ICN protocol not only is independent of the number of vision agents but also doesn't need calibration between vision agents. Therefore, the ICN protocol raises speed, scalability, and modularity of the system. We adapt the ICN protocol in our ubiquitous vision system that we construct in order to make an experiment. Our ubiquitous vision system shows us reliable results and the ICN protocol is successfully operated through several experiments.

• Journal of the Korea Society of Computer and Information
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• v.12 no.6
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• pp.187-192
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• 2007

Conference focus maintains and manages SIP(Session Initiation Protocol) signal connections with total conference participants, and it plays core functions of conference server. When the number of conference participants increases, conference focus restricts scalability of conference as increasing quantify of messages for processing. In this paper, to solve this problem. we propose a user system(conference information agent), which receives conference information from the conference focus and transfers them to the participants it manages. And we design and implement the total system including conference focus. When the conference information agent subscribe to the conference focus, it shows its possession of agent capability and capacity by using SIP SUBSCRIBE message. The conference focus informs to the other party by SIP response message that it was chosen as a conference information agent, and after that the conference focus sends all conference notification messages to it. So load of the conference focus can be reduced by this method. Finally, we have analyzed the performance of our system by experiments.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.37 no.4
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• pp.35-45
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• 2000

The vertex-based boundary encoding scheme is widely used in object-based video coding area and computer graphics due to its scalability with natural looking approximation. Existing single framebased vertex encoding algorithm is not efficient for temporally correlated video sequences because it does not remove temporal redundancy. In the proposed method, a vertex point is selected from not only the boundary points of the current frame but also the vertex points of the previous frame to remove temporal redundancy of shape information in video sequences. The problem of selecting optimal vertex points is modeled as finding shortest path in the directed acyclic graph with weight The boundary is approximated by a polygon which can be encoded with the smallest number of bits for maximum distortion. The temporal redundancy between two successive frames is efficiently removed with the proposed scheme, resulting in lower bit-rate than the conventional algorithms.