• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.8
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• pp.950-953
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• 2016

A packet loss caused TCP segment drop and retransmission. This makes the energy useless, which is consumed to deliver the whole packets of the dropped segment over many hops. In this paper, end-to-end TCP retramission will be analyzed for the effect to energy consumed for delivering data. Especially, this paper will compare and analyze the legacy TCP method and Store-and-Forward method, and the method of computing the energy efficiency to transmission loss. This paper expects that the proposed method can contribute to new energy saving decision or algorithm on diverse data transmission situation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.7
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• pp.605-611
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• 2013

If an accident vehicle propagates emergency messages to other vehicles close to it, the other drivers may realize and avoid the accident spot. In this letter, we propose a broadcast scheme to propagate emergency messages fast in urban VANETs (Vehicular Ad-Hoc Networks) with the help of GPS (Global Position System). In our scheme, a transmitting vehicle chooses the farthest node as the next relay vehicle to propagate emergency messages. And, we suggest an algorithm for intersection recognition and SCF (Store-Carry-Forward) task by taking advantage of periodic hello packets to reduce the propagation time and enhance the delivery ratio.

• KIPS Transactions on Computer and Communication Systems
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• v.3 no.1
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• pp.15-22
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• 2014

Delay-Tolerant Network employs message forwarding based on a Store, Carry and Forward method to conquer no guarantee of continue connectivity. For this reason, a lot of DTN routing scheme have been proposed recently. message forwarding is an important research issue in delay-tolerant network and In this paper, we propose a efficiency DTN routing scheme using node's social relation and expanded Ego-network betweenness centrality. Our simulation results show that it is more efficient to message delivery cost than Epidemic routing, Friendship routing while it has a little performance degradation of message delivery ratio.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.12
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• pp.1417-1422
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• 1991

In this paper we develop an analytic model for end-to-end communication protocols and study the window mechanism for flow control in store-and-forward computer networks. We develop a flow control model in which the parameters of the system are not dynamically adjusted to the stochastic fluctuation of the system load. Simulation results are presented and it is shown that the throughput-delay performance of a network can be improved by proper selection of the design parameter, such as timeout, the number of retransmission, etc.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.9
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• pp.104-109
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• 1999

The flywheel energy storage system using superconducting magnetic bearings is a device to store electrical energy as rotatioal kinetic energy by motor and to convert it to electrical energy by generator when it is necessary. The rotordynamic analysis should be performed with an adequate analytical model and equations of motion to identify the stable driving condition and the dynamic behavior. The critical speed and the unbalance response of superconducting magnetic bearings-flywheel system are studied in this paper. The analytical results show that the system has one forward whirling mode and two backward whirling models below 500rpm. The maximum displacement 0.75mm is detected at the first forward mode (385rpm)through unbalance response analysis. The analytical results are compared with the experimental result by the spin-down test. The experimental result shows that the maximum displacement is 0.7mm at 370rpm.

• Journal of Communications and Networks
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• v.11 no.3
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• pp.306-317
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• 2009

We consider the problem of architecting a reliable content delivery system across an overlay network using TCP connections as the transport primitive. We first argue that natural designs based on store-and-forward principles that tightly couple TCP connections at intermediate end-systems impose fundamental performance limitations, such as dragging down all transfer rates in the system to the rate of the slowest receiver. In contrast, the ROMA architecture we propose incorporates the use of loosely coupled TCP connections together with fast forward error correction techniques to deliver a scalable solution that better accommodates a set of heterogeneous receivers. The methods we develop establish chains of TCP connections, whose expected performance we analyze through equation-based methods. We validate our analytical findings and evaluate the performance of our ROMA architecture using a prototype implementation via extensive Internet experimentation across the PlanetLab distributed testbed.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1983.10a
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• pp.108-111
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• 1983

This paper presents a new method for the optimum capacity assignment in store-and-forward communication networks under a total fixed-capacity constraints. Any two link capacities needed in this method can have the desirable quantites and then other capacities can be obtained from the fixed two link capacities. When the minimum and the maximum capacities that are the quantites of the conventional method are fixed, the total average time delay from the new method is almost the same as that from the conventional method. And when the minimum capacity is fixed, the new method gives smaller average time delay.

• Journal of the Korean Operations Research and Management Science Society
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• v.9 no.2
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• pp.46-55
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• 1984

The purpose of this parer is to provide a survey of the state of the art of routing methods in store-and-forward computer networks. The survey is carried out in line with a new taxonomy： heuristic methods, user-optimization methods, and system-optimization methods. This taxonomy on routing algorithms is based on two viewpoints： the level of optimization and the relative difficulty for the implementation in real computer networks. Some actual methods implemented in real computer networks are surveyed as well as the theoretical studies in the literature. This paper concludes with some points in need of further researches.

• Korean Institute of Interior Design Journal
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• v.26 no.1
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• pp.33-42
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• 2017

Interior design especially the design developments for commercial spaces should ensure the economy of spaces. This is the marketing for space. It is necessary to understand the design elements of commercial space for the efficient using of digital media of space marketing. In this research decided to design application schemes for shopping mall by searching fashion shopping behaviors of users with persona-base scenario approach. Collected the information of users behavior base on case analysis of advance research to make personas. And develop scenario base personas for knowing the needs of users. And then made 4 schemes as the solution. Scheme 1. Customers can get the information and communication with the staff through with media screen in one room of shopping mall. The data of customers can be recorded for providing information or product recommendation personality. Forecast to preferred by group trip or customers that don't like walking around in shopping mall. Scheme 2. Install a media screen at entrance of a store in shopping mall and show special effect to raise customers' attention who walk through from the front of the store. Through with this customers will stay for long time and raise curiosity to get in the store. And the media screen also provide information of store and products. Scheme 3. Customers can get the information of products with using smart phone to scan QR cord in labels of products and record. Customers can finish whole shopping behaviors without the help of store staff. And can make buying decision even have left shopping mall as a online mode. Scheme 4. Store managers can record the products and the environment of store with 360 camera and update to website. Then customers can browse the virtual space with VR glasses. That make customers can have the real shopping experience without being in the store. In this study, have presented schemes of digital media in commercial space. But there are various of commercial space. In this study was presented schemes for shopping mall by searching fashion shopping behaviors of users. And look forward the researches about specific space setting and other type of commercial space for space development.

• Journal of the Korea Society of Computer and Information
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• v.16 no.10
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• pp.147-153
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• 2011

In this paper, we present a new video management technique using forward timeline to efficiently store and delete the videos on a local server. The proposed method is based on capturing the changing preference of the videos according to recentness, frequency, and playback length of the requested videos. For this purpose, we utilize the forward timeline which represents the time area within a number of predefined intervals. The local server periodically measures time popularity and request segment of all videos. Based on the measured data, time popularity and request segment, the local server calculates the mean time popularity and mean request segment of a video using forward timeline. Using mean time popularity and mean request segment of video, we estimate the ranking and allocated storage space of a video. The ranking represents the priority of deletion when the storage area of local server is running out of space and the allocated storage space means the maximum size of storage space to be allocated to a video. In addition, we propose an efficient storage space partitioning technique in order to stably store videos and present a time based free-up storage space technique using the expected variation of video data in order for avoiding the overflow on a local server in advance. The simulation results show that the proposed method performs better than other methods in terms of hit rate and number of deletion. Therefore, our video management technique for local server provides the lowest user start-up latency and the highest bandwidth saving significantly.