• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.3
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• pp.165-171
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• 2009

With rapid growth of Mobile Ad-Hoc network(MANET) and P2P service technologies, many attempts for integration of MANET and P2P service and development of such applications are actively introduced recently. The implementation of stable P2P service, however, is very difficult challenge because of the high mobility of mobile users in MANET. In this paper, we propose an efficient mobile P2P service, which shares and manages multimedia data files efficiently in mobile environment, uses distributed caches to store files considering their popularities in order to achieve high performance. The performance of proposed P2P service is evaluated by an analytic model and compared with those of existing DHT based P2P service in peer-to-peer network.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.3
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• pp.149-154
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• 2015

In this paper proposes a stable marriage algorithm. The proposed algorithm firstly constructs an $n{\times}n$ matrix of men's and women's sum preference over opposite sex $p_{ij}$. It then repeatedly deletes row or column corresponding to the then maximum dispreference sum $_{max}p_{ij}$ until ${\forall}(|r_i|=1{\cap}|c_j|=1)$. If $|r_i|=1$ or $|c_j|=1$ then we select the $p_{ij}$ of $|r_i|=1$ or $|c_j|=1$ then the row or column values are deleted repeatedly until ${\forall}(|r_i|=1{\cap}|c_j|=1)$. When tested on 7 stable marriage problems, the proposed algorithm has proved to improve on the existing solutions.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.2
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• pp.41-47
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• 2016

The times of multiplication for encryption and decryption of cryptosystem is primarily determined by implementation efficiency of the modular exponentiation of $a^b$(mod m). The most frequently used among standard modular exponentiation methods is a standard binary method, of which n-ary($2{\leq}n{\leq}6$) is most popular. The n-ary($1{\leq}n{\leq}6$) is a square-and-multiply method which partitions $b=b_kb_{k-1}{\cdots}b_1b_{0(2)}$ into n fixed bits from right to left and squares n times and multiplies bit values. This paper proposes a variable-length partition algorithm that partitions $b_{k-1}{\cdots}b_1b_{0(2)}$ from left to right. The proposed algorithm has proved to reduce the multiplication frequency of the fixed-length partition n-ary method.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.6
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• pp.257-266
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• 2015

There is no polynomial-time algorithm that can be obtain the optimal solution for economic load dispatch problem with non-convex fuel cost functions. Therefore, electrical field uses quadratic fuel cost function unavoidably. This paper proposes a valve-point optimization (VPO) algorithm for economic load dispatch problem with non-convex fuel cost functions. This algorithm sets the initial values to maximum powers $P_i{\leftarrow}P_i^{max}$ for each generator. It then reduces the generation power of generator i with an average power cost of $_{max}\bar{c}_i$ to a valve point power $P_{ik}$. The proposed algorithm has been found to perform better than the extant heuristic methods when applied to 13 and 40-generator benchmark data. This paper consequently proves that the optimal solution to economic load dispatch problem with non-convex fuel cost functions converges to the valve-point power of each generator.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.6
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• pp.43-49
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• 2015

This paper designs and implements a smart phone safe application program for advanced preventing a danger during a car driving with doing a smart phone. The proposed smart phone safe application program has the aim to increase easily and naturally the concentration when the driver is using of the smart phone during a car driving. Especially when sudden situation occurs, If driver gives up driving conditions, and go to the restaurant, move to tourist resort. It will continue to send the text of driving even if another person is on the phone. In this paper a traffic safety simulation was performed using a fuzzy inference rules in order to solve these problem. The simulation is predicted greatly to decrease to send the auto sending message when the driver gives up suddenly the driving because catching up whether the car is driving or not.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.3
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• pp.111-119
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• 2010

With the rapid progress of wireless technologies today, mobile terminals with multiple access interfaces are emerging. In recent years, WLAN (Wireless Local Area Networks) has become the premier choice for many homes and enterprises. WiMAX (Worldwide Interoperability for Microwave Access) has also emerged as the wireless standard that aims to deliver data over long distances. Therefore, it is important to explore efficient integration methods for delivering multimedia data between heterogeneous wireless networks. In this paper, we developed the simulation models and environments for the mobile multihomed node that has both WiMAX and WLAN interfaces and can move around in both networks by using mobile IP. In order to verify the developed models, we designed and constructed several simulation scenarios, e.g. movement in WiMAX/WLAN, group mobility, MANET, and nested MIP under the various traffic environments such as oneway or bothway UDP packets, FTP traffic, and voice with SIP protocol. The simulation results show that the developed models are useful for mobility studies in various integrated wireless networks.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.4
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• pp.29-37
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• 2013

Multiplayer games typically organized based on a client-server(CS) or peer-to-peer(PP) architecture. The CS architecture is not scalable with the number of players due to a large bandwidth requirement at the server. The PP architecture, on the other hand, introduces significant overhead for the players, as each player needs to check the consistency between its local state and the state of all other players. We then propose a method that combines the merits of CS and PP. In this method, players exchange updates with lower priority in a peer-to-peer manner but communicate directly with a central server for the other updates. As a result, the proposed method has a lower network bandwidth requirement than the server of a CS architecture and the server bandwidth bottleneck is removed. For another important issue about multiplayer games, this method always maintains state consistency among players correctly. The performance of this method is evaluated through extensive simulation experiments and analysis.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.4
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• pp.149-154
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• 2018

There is well known algorithm is a Gale-Shapley algorithm(GSA) for stable marriage problem. The GSA is performed as each man propose to his most favorite woman(MP), then the woman accepts more than one proposal rejects all but her favorite from among those who have proposed to her. This algorithm always gets a stable set of marriages with man-optimal and woman-pessimal. But the woman proposal and man-accept/reject method(WP) is can be get the distinct result. Also, the optimal stable matching may be fail using MP or WP. This paper suggests always get the optimal stable matching on all occasions in order to overcome the shortcomings of MP and WP. The proposed algorithm perform k-opt, k-women exchange with each other for the result of delete at less preference in each woman from MP result. As a result of applied to various experimental data, this algorithm can be get the optimal stable matching that the MP or WP failed to it.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.4
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• pp.123-130
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• 2018

Many massively multiplayer online games(MMOG) use client-server architectures that have enormous server-side bandwidth requirements. In this paper, we propose a region-based hybrid game architecture that combines the advantages of client-server and peer-to-peer architectures, so that only critical events changing game state are processed by the server. In this hybrid architecture, the central server divides the game into regions and assigns a player as a regional server to distribute important updates for that region. Thus, the central server sends state updates to the players through the regional servers. All players in the same region directly exchange updates without affecting game state. This division of labor greatly reduces server bandwidth significantly and enables it to serve larger number of concurrent players. Our experiments show that the region-based hybrid architecture with three-level hierarchy scales better than the client-server architecture, saving considerable bandwidth at the central server while requiring enough bandwidth of players acting as regional servers.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.4
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• pp.171-176
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• 2020

This paper proposes polynomial-time algorithm for maximum weighted independent set(MWIS) problem that is well known as NP-hard. The known algorithms for MWIS problem are polynomial-time to specialized in particular graph type, distributed, or clustering method. But there is no unified algorithm is suitable to all kinds of graph types. Therefore, this paper suggests unique polynomial-time algorithm that is suitable to all kinds of graph types. The proposed algorithm merges the maximum weighted vertex v_i and maximum weighted vertex v_j that is not adjacent to v_i. As a result of apply to undirected graphs and trees, this algorithm can be get the optimal solution. This algorithm improves previously known solution to new optimal solution.