• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.1B
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• pp.41-51
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• 2010

In this study, runoff simulation was carried out in the area of Bisan 7-dong, Seo-gu, Daegu as drainage basin and the effects of the installation of underground storage facilities were analyzed during heavy rainfall. SWMM model was used for the runoff and pipe network analysis on Typhoon Maemi, 2003. 2-D inundation analysis model based on diffusion wave was employed for inundation analysis and to verify computed inundation areas with observed inundation trace map. The simulation results agree with observed in terms of inundation area and depth. Also, the effects of flood damage mitigation were analyzed through the overflow discharge and 2-D inundation analysis, depending upon whether the underground storage facility is installed or not. When the underground storage facility ($W:120m{\times}L:180m{\times}H:1.7m$) is installed, volume of overflow could be reduced by 72% and flooding area could be reduced by 40.1%. When the underground storage facility ($W:120m{\times}L:180 m{\times}H:2.0m$) is installed, volume of overflow could be reduced by 84.8% and flooding area could be reduced by 50.6%. When the underground storage facility ($W:120m{\times}L:180m{\times}H:2.2m$) is installed, volume of overflow could be reduced by 94% and flooding area could be reduced by 91.2%. There is no overflow of manhole, when the height of storage facility is 2.5 m. It is expected that the study results presented through quantitative analysis on the effects of underground facilities can be used as base data for socially and economically effective installation of underground facilities to prevent flood damage.

• Journal of KIISE:Computer Systems and Theory
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• v.36 no.3
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• pp.140-148
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• 2009

Recent advances in communication and multimedia technologies make it possible to provide video-on-demand(VOD) services and people can access video servers over the Internet at any time using their electronic devices, such as PDA, mobile phone and digital TV. Each device has different processing capabilities, energy budgets, display sizes and network connectivities. To support such diverse devices, multiple versions of videos are needed to meet users' requests. In general cases, VOD servers cannot store all the versions of videos due to the storage limitation. When a device requests a stored version, the server can send the appropriate version immediately, but when the requested version is not stored, the server first converts some stored version to the requested version, and then sends it to the client. We call this conversion process transcoding. If transcoding occurs frequently in a VOD server, the CPU resource of the server becomes insufficient to response to clients. Thus, to admit as many requests as possible, we need to maximize the CPU availability. In this paper, we propose a new algorithm to select versions from those stored on disk using a branch and bound technique to maximize the CPU availability. We also explore the impact of these storage management policies on streaming to heterogeneous users.

• Spatial Information Research
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• v.20 no.3
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• pp.95-106
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• 2012

Recently, with increase and development of the wireless access network area, u-GIS Service is supported in various fields. Especially, spatio-temporal data is used in the mobile environment for the u-GIS service. However, there is no standard for the spatio-temporal data used in different spaces, spatio-temporal data processing technology is necessary to makes interoperability among mobile u-GIS services. Furthermore, it is also necessary to develop the system of gathering, storing, and managing the spatio-temporal data in consideration of small capacity and low performance of mobile devices. Therefore, in this paper, we designed and implemented a spatio-temporal query processing system based on GML to manage spatio-temporal data efficiently in the mobile environment. The spatio-temporal query processing system based on GML can offer a structured storage method which maps a GML schema to a storage table and a binary XML storage method which uses the Fast Infoset technique, so as to support interoperability that is an important feature of GML and increase storage efficiency. we can also provide spatio-temporal operators for rapid query processing of spatio-temporal data of GML documents. In addition, we proved that this system can be utilized for the u-GIS service to implement a virtual scenario.

• The KIPS Transactions:PartD
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• v.12D no.6 s.102
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• pp.915-920
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• 2005

In this paper we expanded a existing web based B2B system to support users in low speed network. To guarantee shared dat a consistency between clients and a server, we proposed a method of data change detection by using a time stamp tree and the performance analysis of the proposed method was proved by a simulation. Under the worst condition that leaf nodes of a times tamp tree were changed uniform distribution, the simulation result showed that the proposed method was more efficient than a sequential detection until the percentage of changed nodes were below $15\%$. According to our observation, the monthly average of data change was below $7\%$ on a web-based construction MRO B2B system or a company A from April 2004 to August 2004. Therefore the Proposed method improved performance of data change detection in practice. The proposed method also reduced storage consumption in a server because it didn't require a server to store replicated data for every client.

• Journal of the Korea Society of Computer and Information
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• v.10 no.6 s.38
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• pp.153-166
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• 2005

Existing single cache structure has shown difference of hit-ratio according to individually replacement strategy However. It needs new improved cache structure for reducing network traffic and providing advanced hit-ratio. Therefore, this Paper design push agent model using dual cache for increasing hit-ratio by reducing server overload and network traffic by repetition request of persistent and identical information. In this model proposes dual cache structure to do achievement replace gradual cache using by two caches storage space for reducing server overload and network traffic. Also, we show new cache replace techniques and algorithms which executes data update and delete based on replace strategy of Log(Size) +LRU, LFU and PLC for effectiveness of data search in cache. And through an experiment, it evaluates Performance of dual cache push agent model.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2014.06a
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• pp.254-257
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• 2014

Recently, various applications using real-time face detection have been developed as face recognition technology and hardware grows. While network service is developing and video instruments costs lower, it is needed that smart surveillance camera and service using network camera based on IP and face detection technology. However, videos should be compressed for reducing network bandwidth and storage capacity in surveillance system. As it requires high-level improvement of system performance when all the compressed frames are processed in a face detection program, fast face detection method is needed. In this paper, not only a fast way of algorithm using Haar like features and adaboost learning and motion information but also an application on broadcast system is suggested.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.5
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• pp.1284-1288
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• 2008

Recently, there is increasing the development requirement of middleware and interface for GPS(Global Positioning System), RFID(Radio Frequency IDentification), sensor networks. GPS supports a useful location based service. RFID supports products logistic and distribution services through the identification. A sensor network collects a context information, such as humidity, temperature and atmospheric pressure. This paper implements and verifies a integrated service middleware for supporting efficiently process of sensing data collected from RFID, GPS and sensor network. This middleware have the temporary store function, the redundancy exclusion function, certification function, the classification function and the database storage function. Additionary, this middleware connects with low-level adaptor using socket interface and supports the high-level application services using database connection. Therefore, user can develop easily various many ubiquitous application system using proposed middleware instead of each RFID middleware, GPS middleware and, middleware based on sensor network.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.4
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• pp.813-820
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• 2009

This paper describes the realization of ubiquitous healthcare monitoring system using wearable pulse oximeter based on a wireless sensor network. In order to obtain information of oxygen saturation from a patient, a small size and low power consumption wearable pulse oximeter was designed. Information of oxygen saturation collected by wireless sensor node was transmitted wirelessly to a base-station for storage and display purposes via wireless sensor network. Wireless sensor nodes were programmed by TinyOS application to perform data acquisition and transmission. Lab VIEW server program was designed to monitor information of oxygen saturation and process the measured PPG (photo plethysmogram) signals to APG(Accelerated plethysmogram) signals by appling second order derivatives. PPG signals are simple and cost effective technique to measure blood volume change.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.12B
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• pp.1359-1370
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• 2009

In wireless sensor networks, data dissemination is based on data-centric routing that well matches the publish/subscribe communication paradigm. The publish/subscribe paradigm requires decoupling properties: space, time, and synchronization decoupling. For large-scale applications, the three decoupling properties provide scalability and robust communication. However, existing data dissemination schemes for wireless sensor networks do not achieve full decoupling. Therefore, we propose a novel data dissemination scheme that fully accomplishes the three decoupling, called ARBIETER. ARBITER constructs an independent network structure as a logical software bus. Information interworking between publishers and subscribers is indirectly and asynchronously performed via the network structure. ARBITER also manages storage and mapping of queries and data on the structure because of supporting different time connection of publishers and subscribers. Our simulation proves ARBITER show better performance in terms of scalability, network robustness, data responsibility, mobility support, and energy efficiency.

• Spatial Information Research
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• v.19 no.3
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• pp.43-52
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• 2011

Recently, interest in location-based service (LBS) which utilizes a DBMS in mobile system environment has been increasing, and it is expected to overcome the existing file-based system's limitation in advanced in-vehicle system by utilizing DBMS's advantages such as efficient storage, transaction management, modelling and spatial queries etc. In particular, the road network data corresponds to the most essential domain in a route planning system, which needs efficient management and maintenance. Accordingly, this study aims to develop an efficient graph-based geodata model for topological network data and to support dynamic path computation algorithm based on heuristic approach in mobile LBS system. To achieve this goal, we design a data model for supporting the hierarchy of network, and implement a path planning system to evaluate its performance in mobile LBS system. Last but not least, we find out that the designed path computation algorithm with hierarchical graph model reduced the number of nodes used for finding and improved the efficiency of memory.