• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.8
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• pp.1486-1491
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• 2017

In this paper, we propose a private multimedia caching scheme based on wireless local area network (WLAN) to improve the quality of service for high capacity and high quality multimedia streaming services which are recently increasing and to reduce the traffic load of core networks. The proposed caching scheme stores multimedia in the storage device mounted on WLAN APs and provides streaming services on its own without Internet connection in accordance with the request from clients. We have implemented a test network based on real commercial networks and measured the performance of the proposed caching scheme in terms of frames per second (FPS) and buffering time. According to the performance measurement results, the proposed caching scheme can reduce the average buffering time by 73.3% compared to the conventional streaming scheme. In addition, the proposed caching scheme can also improve the average FPS by 71.3% compared to the conventional streaming scheme.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.5
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• pp.870-878
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• 2008

The level of security of most sensor nodes that comprise the sensor networks is low, but because of the low computing power and small storage capacity, it is even very difficult to apply a security algorithm efficiently to the sensor nodes. Therefore, preventing the join of an illegal node to a sensor network is impossible, and the transmitting information is easily exposed and overheard when the transmitting algorithm of the sensor node is hewn. In this paper, we propose a group key management scheme for the sensor network using polar coordinates, so that the sensor nodes can deliver information securely inside a cluster and any illegal node is prevented from joining to the cluster where a sensor network is composed of many clusters. In the proposed scheme, all of the sensor nodes in a cluster set up the authentication keys based on the pivot value provided by the CH. The intensive simulations show that the proposed scheme outperforms the pair-wise scheme in terms of the secure key management and the prevention of the illegal nodes joining to the network.

• 지역과문화
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• v.7 no.2
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• pp.57-84
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• 2020

The Literature Museum Network aims to realize the legislative purpose of the Literature Promotion Act and achieve balanced development of local literature centers across the country. In the Literature Museum Network, the literature museum network support center will be established by region to take charge of cooperation projects between local literature centers, which will be the culmination of the National Literature Museum of Korea. It is intended to test-run various projects planned by the Munhakwan Network Support Center to create derivative contents, or to establish a regional hub literature center in charge of education and other affairs of the literature museum's workforce. If the existing metropolitan administrative districts are used to form zones, the entire country can be organized into four zones. They include the Seoul-Gyeonggi Literature Museum Network (23 local literature centers), the Gangwon Chungcheong Literature Museum Network (32 local literature centers), the Yeongnam Literature Museum Network (30 local literature centers), and the Honam Jeju Literature Museum Network (22 local literature centers). One literature museum network support center will be established for each region and one local literature center will be selected as the hub literature center. The Literature Hall Network Support Center is in charge of collecting and managing literary materials, developing contents and programs, promoting and foreign cooperation, etc. The hub literature museum will be in charge of pilot operation of content and programs, training and education of experts in the literature museum, and running joint storage facilities. This structural system and efficient operation of the literature museum network will ultimately provide an opportunity for the formation of cultural governance in which the power and public nature of the establishment of literary promotion infrastructure are secured.

• Journal of Sensor Science and Technology
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• v.22 no.1
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• pp.76-83
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• 2013

A real-time wireless monitoring and analysis methods using the wearable PPG sensor to estimate cardiovascular condition is studied for ubiquitous healthcare service. A small size and low-power consuming wearable photoplethysmogram (PPG) sensor is designed as a wrist type device and connected with the IP node assigned its own IPv6 address. The measured PPG waveform in the IP node is collected and transferred to a central server PC through the IP-enabled wireless network for storage and analysis purposes. A monitoring and analysis program is designed to process the accelerated plethysmogram (APG) waveform by applying the second order derivatives to analyze systolic waves as well as heart rate variability analysis from the measured PPG waveform. From our results, the features of cardiovascular condition from individual's PPG waveform and estimation of vascular compliance by the comparison of APG-aging index (AI) and ratio of LF/HF are demonstrated.

• Spatial Information Research
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• v.4 no.1
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• pp.43-54
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• 1996

The purpose of this study is to provide GIS application to the emergency medical service management system in the Seoul area. Two wards, Kangnam-Gu and Songpa-Gu, were selected for a pilot study subject. The main focus of the study was to develope the network system using GIS which could select the most available hospital from the site being emergency case and advise the minimum path to the hospital. ARC/INFO pc version was need to implemeni an indexing system for automated mapping and data storage. The developed system, "Emergency Medical System based on GIS ${\ulcorner}$EMS/GIS${\lrcorner}m$", consists of the cartographic database and vehicle transportation system. The results suggest that EMS/GIS network are needed to connect the local transportation network between major emergency care hospitals and central conirol tower in the near future. If the EMS/GIS system could be more developed based in further analysis, it would be the most useful economical and efficient for emergency medical service with mutual aid system.al aid system.

• Proceedings of the KIEE Conference
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• 2003.11b
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• pp.207-210
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• 2003

In this paper, we have implemented the DVR system which is controlled far away, and added a function of TCP/IP Network for image data and control signal transmission, the DVR system has the advantage of easy to search and of no loss in stored quality. The continuously declining price of the hard drive presents the opportunity for the DVR system to displace the analog system. Also, with spread of the internet the needs of PC based the DVR system increase. Therefore, we have implemented DVR system within a function of network. When obtained image through the PTZ camera is transmitted to digital form, very large space of storage is required, hence image compression is essential. We use JPEG2000 for compression of image. JPEG2000 adopt DWT by means of transform. DWT concentrates important information of image on subband and has feature of multi-resolution. It is effective in order to express image. Thus JPEG2000 is suitable for image compression in DVR system. The significance of this paper is to design the DVR system which is controlled through TCP/IP network and to implement transmission of image compression using JPEG2000.

• Korean Management Science Review
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• v.25 no.2
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• pp.89-109
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• 2008

As the importance of logistics is increasing, Enterprises try to design the supply chain(SC) network to minimize the total costs considering inventory holding cost, transportation cost and apply the efficient strategies of supply chain based on SC network. Despite of this efforts, Calculating the logistics costs without reflecting the real components of logistics like the packaging cost, transportation related cost, storage cost, loading & unloading cost, and distribution costs, the companies has many limitation to calculate the logistics cost of real enterprise. For overcoming such problem, this paper is aimed at establishing SC strategies which can be an efficient alternative for a decision making on supply chain, based on existing reference and current logistics networks of 'L' company in Korea. Also, we analyze the interaction effects between strategies as well as install the optimal SC network reflecting concrete logistics components from the viewpoint of total logistics costs using the simulation and statistic methods. we expect that analysis results of this paper would be applied various industries and be utilized to the efficient tools for the decision making by planing and execution of the logistics budget from enterprises.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.9
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• pp.2040-2048
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• 2010

In contemporary society, though convenience and efficiency of work using information system is growing high, adverse effect problems of malignant code, system hacking, information leak by insiders due to the development of the network are raising their head daily. Because of this, enormous work forces and expenses for the recovery and management of system is needed. The existing system can be divided into two aspects: security solution which surveils and treats virus and malignant codes, and network management solution which observes the system of computer, and practices maintenance and repair such as management, recovery, backup. This treatise applied Active Write Filter mechanism and the technology based on NFS and complemented the maintenance problems of user data of the existing system and designed the system which enables solving problems of intellectual property right such as information protection and illegal work.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.09a
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• pp.27-30
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• 2001

Flow and transport at fracture intersections, and their effects on network scale transport, are investigated in three-dimensional random fracture networks. Fracture intersection mixing rules complete mixing and streamline routing are defined in terms of fluxes normal to the intersection line between two fractures. By analyzing flow statistics and particle transfer probabilities distributed along fracture intersections, it is shown that for various network structures with power law size distributions of fractures, the choice of intersection mixing rule makes comparatively little difference in the overall simulated solute migration patterns. The occurrence and effects of local flows around an intersection (local flow cells) are emphasized. Transport simulations at fracture intersections indicate that local flow circulations can arise from variability within the hydraulic head distribution along intersections, and from the internal no flow condition along fracture boundaries. These local flow cells act as an effective mechanism to enhance the nondiffusive breakthrough tailing often observed in discrete fracture networks. It is shown that such non-Fickian (anomalous) solute transport can be accounted for by considering only advective transport, in the framework of a continuous time random walk model. To clarify the effect of forest environmental changes (forest type difference and clearcut) on water storage capacity in soil and stream flow, watershed had been investigated.

• The Transactions of the Korea Information Processing Society
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• v.7 no.2S
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• pp.577-593
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• 2000

A distributed video-on-demand (VoD) system is one where collection of video data is located at dispersed sites across a computer network. In a single site environment, a local video server retrieves video data from its local storage device. However, in the setting of a distributed VoD system, when a customer requests a movie from the local server, the server may need to interact with other servers located across the network. In this paper, we present three types of presentation plans that a local server must construct in order to satisfy the customer request. Informally speaking, a presentation plan is a temporally synchronized detailed sequence of steps that the local server must perform for presenting the requested movie to the customer. This involves obtaining commitments from other video servers, obtaining commitments from the network service provider, as well as making commitments of local resources, within the limitations of available bandwidth, available buffer, and customer data consumption rates. Furthermore, for evaluating the goodness of a presentation plan, we introduce two measures of optimality for presentation plans: minimizing wait time for a customer, and minimizing access bandwidth is used. We develop algorithms to compute optimal presentation plans for all three types, and carry out extensive experiments to compare their performance. We have also mathematically proved certain results for the presentation plans that had previously been verified experimentally in the literature.