• Journal of Information Processing Systems
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• v.16 no.6
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• pp.1447-1458
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• 2020

This paper describes a structured overlay network scheme based on multiple different time intervals. Many types of data (e.g., sensor data) can be requested at specific time intervals that depend on the user and the system. These queries are referred to as "interval queries." A method for constructing an overlay network that efficiently processes interval queries based on multiple different time intervals is proposed herein. The proposed method assumes a ring topology and assigns nodes to a keyspace based on one-dimensional time information. To reduce the number of forwarded messages for queries, each node constructs shortcut links for each interval that users tend to request. This study confirmed that the proposed method reduces the number of messages needed to process interval queries. The contributions of this study include the clarification of interval queries with specific time intervals; establishment of a structured overlay network scheme based on multiple different time intervals; and experimental verification of the scheme in terms of communication load, delay, and maintenance cost.

• International Journal of Internet, Broadcasting and Communication
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• v.14 no.3
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• pp.258-269
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• 2022

In these days, innovative functions are required to unmanned parcel delivery lockers. As non-face-to-face transactions become the center due to the recent COVID-19 pandemic, many problem occurs in society such as theft crimes and lack of loading space. Therefore, New concept storage device is developed in korea. It has the functions that minimizes empty spaces by using the internal transport device to enable efficient space loading and refrigerate goods such as foods. In order to systematically approach the system design of the unmanned parcel delivery lockers which is the new function is applied, We applied model-based system engineering to improve the development efficiency and use a system modeling language to express the system. We conducted interworking research of CAD data including system modeling and design data. it is expected that this method will increase the effective development efficiency such as maintenance traceability and reduction of development period and cost.

• International conference on construction engineering and project management
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• 2011.02a
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• pp.311-317
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• 2011

There is a growing concern in reducing greenhouse gas emissions all over the world. The U.K. has set 34% target reduction of emission before 2020 and 80% before 2050 compared to 1990 recently in Post Copenhagen Report on Climate Change. In practise, Life Cycle Cost (LCC) and Life Cycle Assessment (LCA) tools have been introduced to construction industry in order to achieve this such as. However, there is clear a disconnection between costs and environmental impacts over the life cycle of a built asset when using these two tools. Besides, the changes in Information and Communication Technologies (ICTs) lead to a change in the way information is represented, in particular, information is being fed more easily and distributed more quickly to different stakeholders by the use of tool such as the Building Information Modelling (BIM), with little consideration on incorporating LCC and LCA and their maximised usage within the BIM environment. The aim of this paper is to propose the development of a model-based LCC and LCA tool in order to provide sustainable building design decisions for clients, architects and quantity surveyors, by then an optimal investment decision can be made by studying the trade-off between costs and environmental impacts. An application framework is also proposed finally as the future work that shows how the proposed model can be incorporated into the BIM environment in practise.

• Journal of the Korea Society of Computer and Information
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• v.19 no.2
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• pp.11-19
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• 2014

In this paper, we build server consolidate virtualization focusing on NT server dilapidated and through analysis of the effect of this, has been presented the following results. First, it was possible to obtain an increase in the constant temperature constant humidity chamber efficiency by securing the upper surface space for computing data center mounted virtualization integration server servers multiple physical. Second, by the deployment of virtualization of a large server dilapidated, the introduction of new resources and the cost of maintaining computerized data center and reduce power consumption, the reduction of hardware introduction of additional due to the new server deployment it was possible to derive a cost reduction effect. We obtain the reduction of 89% and 79% compared with conventional consumption of cooling and power savings of the top surface, respectively. Integration of NT servers are virtualized can be expected to change in the Green-IT to contribute to providing the maintenance costs of computing centers in the future as well as current. Building a virtualization server integration applied in this paper can be similarly applied to the UNIX system and to integrate the server group other.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.6
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• pp.2851-2873
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• 2016

Cloud storage as a service provides high scalability and availability as per need of user, without large investment on infrastructure. However, data security risks, such as confidentiality, privacy, and integrity of the outsourced data are associated with the cloud-computing model. Over the year's techniques such as, remote data checking (RDC), data integrity protection (DIP), provable data possession (PDP), proof of storage (POS), and proof of retrievability (POR) have been devised to frequently and securely check the integrity of outsourced data. In this paper, we improve the efficiency of PDP scheme, in terms of computation, storage, and communication cost for large data archives. By utilizing the capabilities of JAR and ZIP technology, the cost of searching the metadata in proof generation process is reduced from O(n) to O(1). Moreover, due to direct access to metadata, disk I/O cost is reduced and resulting in 50 to 60 time faster proof generation for large datasets. Furthermore, our proposed scheme achieved 50% reduction in storage size of data and respective metadata that result in providing storage and communication efficiency.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.5
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• pp.895-900
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• 2023

We study low-complexity graph sampling which selects a subset of nodes from graph nodes so as to reconstruct the original signal from the sampled one. To achieve complexity reduction, we propose a graph sampling algorithm with thresholding which selects a node with a cost lower than a given threshold at each step without fully searching all of the remaining nodes to find one with the minimum cost. Since it is important to find the threshold as close to a minimum cost as possible to avoid degradation of the reconstruction performance, we present a mathematical expression to compute the threshold at each step. We investigate the performance of the different sampling methods for various graphs, showing that the proposed algorithm runs 1.3 times faster than the previous method while maintaining the reconstruction performance.

• Journal of KIISE:Databases
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• v.33 no.2
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• pp.188-200
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• 2006

Once a continuous query, which is commonly used in sensor networks, is issued, the query is executed many times with a certain interval and the results of those query executions are collected to the base station. Since this comes many communication messages continuously, it is important to reduce communication cost for collecting data to the base station. In sensor networks, in-network processing reduces the number of message transmissions by partially aggregating results of an aggregate query in intermediate nodes, or merging the results in one message, resulting in reduction of communication cost. In this paper, we propose a routing tree for sensor nodes that qualify the given query predicate, called the query specific routing tree(QSRT). The idea of the QSRT is to maximize in-network processing opportunity. A QSRT is created seperately for each query during dissemination of the query. It is constructed in such a way that during the collection of query results partial aggregation and packet merging of intermediate results can be fully utilized. Our experimental results show that our proposed method can reduce message transmissions more than 18% compared to the existing one.

• Journal of Broadcast Engineering
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• v.19 no.3
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• pp.355-361
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• 2014

In this paper, we propose a complexity reduction method of sample adaptive offset (SAO), which is an in-loop filter in high-efficiency video coding (HEVC). In the conventional SAO, an offset value is calculated for each coding tree block (CTB) to minimize the error between the original and reconstructed images. In order to determine the optimal offset value, all offset candidates are examined and the offset value that leads to the smallest rate-distortion cost is chosen. Thus, SAO occupies a significant amount of the computational complexity in the HEVC encoder. In the proposed method, we determine the least-used band (LUB) by considering the statistical characteristics of offset values and without processing the offset value included in the LUB. Also, in the offset value decision stage, we check only a certain number of candidates rather than all of them. Experimental results show that the proposed method reduces the encoding time by approximately 8.15% without yielding a significant loss in terms of coding efficiency.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.8
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• pp.735-742
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• 2016

The Low-Rate WPAN is a short range wireless networking technology characterized by low-rate, low-power, low complexity and low-cost. The LR-WPAN controls wireless channel access among network devices based on the contention-based CSMA/CA algorithm. Therefore, frame collisions may take place at any time, leading to the severe degradation of network performance. This paper proposes a new algorithm that changes back-off periods adaptively in the CSMA/CA process depending on network conditions, resulting in the reduction of frame collisions. Throughout extensive simulations, it turns out that varying the back-off periods dynamically shows better performance than maintaining the fixed back-off periods.

• 한국정보통신설비학회:학술대회논문집
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• 2007.08a
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• pp.64-68
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• 2007

Commercial WiBro and 3G HSDPA services are launched last year in order to provide high speed wireless Internet access and multimedia service. Currently mobile communication service providers concentrate on the deployment of indoor mobile network since indoor traffic is remarkably increased. For fine indoor wireless communication, an installation of access point system via Public IP network which is called Femtocell is required. The development of indoor Femtocell system must be considered in the viewpoint of low hardware complexity, cost reduction, interlocking with WiBro/HSDPA network without change of network component and easy element management. In this paper, we review the implementation issue and technology of dual mode AP which provides WiBro and HSDPA signal to the user simultaneously. Especially, we describe on the HSDPA Femtocell standardization status and possible 3 types of HSDPA communication module development design. Furthermore we analyze the merits and demerits of each HSDPA Femtocell design type and propose a system which enables handover between indoor HSDPA Femtocell and outdoor commercial HSDPA mobile network.