• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.05a
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• pp.543-545
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• 2011

The concern which is abundant in MANET VoIP for comprising the mobility guarantee and mobile network is received without the infrastructure system between the mobile terminal node. However, because the access of system and border is easy, the issue which is big in the security problem becomes more than the wired network system with this convenience by the foreign network attacker differently. In this paper, we would like to the fundamental web network, NAT and concluding the security problem technology in which Firewall can inquire on MANET VoIP and whether it is appropriate or not which can solve this is proposed.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2001.05a
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• pp.65-68
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• 2001

RBFN has some problem that because the basis function isnt orthogonal to each others the number of used basis function goes to big. In this reason, the Wavelet Neural Network which uses the orthogonal basis function in the hidden node appears. In this paper, we propose the composition method of the actual function in hidden layer with the scaling function which can represent the region by which the several wavelet can be represented. In this method, we can decrease the size of the network with the pure several wavelet function. In addition to, when we determine the parameters of the scaling function we can process rough approximation and then the network becomes more stable. The other wavelets can be determined by the global solutions which is suitable for the suggested problem using the genetic algorithm and also, we use the back-propagation algorithm in the learning of the weights. In this step, we approximate the target function with fine tuning level. The complex neural network suggested in this paper is a new structure and important simultaneously in the point of handling the determination problem in the wavelet initialization.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.11a
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• pp.614-618
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• 2002

Although there are a lot of file sharing mechanisms in the Internet such as NFS and P2P, FTP is one of the most common mechanisms used until now. In this paper, we propose a more enhanced file sharing mechanism, the Distributed File Server (DFS) method. The most remarkable feature of DFS is that it can be simply adopted in the current Internet FTP services by locating a DFS node between existing FTP servers and clients without changing any existing file transfer environment. To verify the proposed mechanism we implemented a DFS prototype on RedHat 7.2 system and we finally show that it can reduce the file storage problem caused by big-sized multimedia data.

• Proceedings of the Korea Information Processing Society Conference
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• 2018.10a
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• pp.110-113
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• 2018

본 논문은 최근 데이터 집약형과학분야 연구개발의 비약적인 발전과 관측, 실험, 분석 장비들의 고도화에 따라 생산되는 과학데이터의 빅데이터화, 고부가가치화 등으로 연구 패러다임의 변화가 빅데이터 중심으로 가속되고 있다. 이러한 과학 빅데이터는 ExaByte 급의 대용량으로서 한 곳에서 관리되기보다는 전 세계적으로 분산되어 관리 운영되고 있다. 응용연구자들은 이러한 과학 빅데이터에 대한 초고속 전송/저장/공유에 대한 요구가 높아지고 있으며, 이러한 문제의 해결을 위해 ScienceDMZ 기반의 다양한 고속전송환경이 구축 개발되고 있다. 따라서 본 논문에서는 장러기 빅데이터 전송을 위한 ScienceDMZ의 핵심 기술인 DTN(Data Transfer Node)을 통한 빅데이터의 장거리 전송 시 고대역 네트워크 환경과 시스템 성능에 대한 통합 모니터링 환경을 구축 개발하였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.7
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• pp.1308-1313
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• 2008

Neighbor knowledge in wireless ad hoc networks provides important functionality for a number of protocols. The neighbor knowledge is acquired via Hello packets. Hello packets are periodically broadcasted by the nodes which want to advertise their existence. Usage of periodic Hello packet, however, is a big burden on the wireless ad hoc networks. This paper deals with an approach where each node acquires neighbor knowledge by observing not only Hello packets but also broadcasting packets. Analysis and computer simulation results show that the method using broadcast packets offers significant improvement over the method using Hello packet only. When the required hello packet transmission interval and the average broadcasting interval are equal, the overhead reduction is about 42%.

• Journal of Multimedia Information System
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• v.6 no.3
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• pp.139-146
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• 2019

This paper, wireless internet such as Wi-Fi has a vulnerability to security. Blockchain also means a 'Ledger' in which transaction information that occurs on a public or private network is encrypted and shared among the network participants. Blockchain maintains information integrity by making it impossible for a particular node to tamper with information arbitrarily, a feature that would result in changes in the overall blockchain hash value if any one transaction information that constitutes a block was changed. The complete sharing of information through a peer-to-peer network will also cripple hacking attempts from outside, targeting specialized nodes, and prepare for the "single point of failure" risk of the entire system being shut down. Due to the value of these Blockchain, various types of Blockchain are emerging, and related technology development efforts are also actively underway. Various business models such as public block chains such as Bitcoin, as well as private block chains that allow only certain authorized nodes to participate, or consortium block chains operated by a select few licensed groups, are being utilized. In terms of technological evolution, Blockchain also shows the potential to grow beyond cryptocurrency into an online platform that allows all kinds of transactions with the advent of 'Smart Contract'. By using Blockchain technology, the company makes suggestions to overcome the vulnerability of wireless Internet.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.21 no.3
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• pp.75-88
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• 2011

Messages need to transmit to the neighbors securely in wireless sensor network, because a sensor node is deployed in hostile area. Thus it is necessary to support secure communication. One of the most important communication part is secure multicast. Especially, group rekeying is a big problem for multicast key management. So, group rekeying must be proceed securely when secrete information is exposed by attacker. Many group rekeying schemes have been studied for ad hoc networks. However, these schemes are Ill1desirable in WSNs. In this paper, we proposed a novel group rekeying scheme in WSNs that it has very powerful security.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.18 no.6
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• pp.1599-1618
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• 2024

Access control has always been one of the effective methods to protect data security. However, in new computing environments such as big data, data resources have the characteristics of distributed cross-domain sharing, massive and dynamic. Traditional access control mechanisms are difficult to meet the security needs. This paper proposes CACM-MMSR to solve distributed cross-domain access control problem for massive resources. The method uses blockchain and smart contracts as a link between different security domains. A permission decision model migration method based on access control logs is designed. It can realize the migration of historical policy to solve the problems of access control heterogeneity among different security domains and the updating of the old and new policies in the same security domain. Meanwhile, a semantic reasoning-based permission decision method for unstructured text data is designed. It can achieve a flexible permission decision by similarity thresholding. Experimental results show that the proposed method can reduce the decision time cost of distributed access control to less than 28.7% of a single node. The permission decision model migration method has a high decision accuracy of 97.4%. The semantic reasoning-based permission decision method is optimal to other reference methods in vectorization and index time cost.

• Journal of Internet Computing and Services
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• v.15 no.3
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• pp.45-52
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• 2014

The Ubiquitous-City (U-City) is a smart or intelligent city to satisfy human beings' desire to enjoy IT services with any device, anytime, anywhere. It is a future city model based on Internet of everything or things (IoE or IoT). It includes a lot of video cameras which are networked together. The networked video cameras support a lot of U-City services as one of the main input data together with sensors. They generate huge amount of video information, real big data for the U-City all the time. It is usually required that the U-City manipulates the big data in real-time. And it is not easy at all. Also, many times, it is required that the accumulated video data are analyzed to detect an event or find a figure among them. It requires a lot of computational power and usually takes a lot of time. Currently we can find researches which try to reduce the processing time of the big video data. Cloud computing can be a good solution to address this matter. There are many cloud computing methodologies which can be used to address the matter. MapReduce is an interesting and attractive methodology for it. It has many advantages and is getting popularity in many areas. Video cameras evolve day by day so that the resolution improves sharply. It leads to the exponential growth of the produced data by the networked video cameras. We are coping with real big data when we have to deal with video image data which are produced by the good quality video cameras. A video surveillance system was not useful until we find the cloud computing. But it is now being widely spread in U-Cities since we find some useful methodologies. Video data are unstructured data thus it is not easy to find a good research result of analyzing the data with MapReduce. This paper presents an analyzing system for the video surveillance system, which is a cloud-computing based video data management system. It is easy to deploy, flexible and reliable. It consists of the video manager, the video monitors, the storage for the video images, the storage client and streaming IN component. The "video monitor" for the video images consists of "video translater" and "protocol manager". The "storage" contains MapReduce analyzer. All components were designed according to the functional requirement of video surveillance system. The "streaming IN" component receives the video data from the networked video cameras and delivers them to the "storage client". It also manages the bottleneck of the network to smooth the data stream. The "storage client" receives the video data from the "streaming IN" component and stores them to the storage. It also helps other components to access the storage. The "video monitor" component transfers the video data by smoothly streaming and manages the protocol. The "video translator" sub-component enables users to manage the resolution, the codec and the frame rate of the video image. The "protocol" sub-component manages the Real Time Streaming Protocol (RTSP) and Real Time Messaging Protocol (RTMP). We use Hadoop Distributed File System(HDFS) for the storage of cloud computing. Hadoop stores the data in HDFS and provides the platform that can process data with simple MapReduce programming model. We suggest our own methodology to analyze the video images using MapReduce in this paper. That is, the workflow of video analysis is presented and detailed explanation is given in this paper. The performance evaluation was experiment and we found that our proposed system worked well. The performance evaluation results are presented in this paper with analysis. With our cluster system, we used compressed $1920{\times}1080(FHD)$ resolution video data, H.264 codec and HDFS as video storage. We measured the processing time according to the number of frame per mapper. Tracing the optimal splitting size of input data and the processing time according to the number of node, we found the linearity of the system performance.

• Journal of Korea Water Resources Association
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• v.31 no.6
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• pp.779-793
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• 1998

In this study, for the purpose of water supply planning, we propose a sophisticated multi-period mixed integer programming model that can coordinate the behavior of multi-reservoir operation, minimizing unnecessary spill. It can simulate the system with operating rules which are self- generated by the optimization engine in the algorithm. It is an optimization model in structure, but it indeed simulates the coordinating behavior of multi-reservoir operation. It minimizes the water shortfalls in demand requirements, maintaining flood reserve volume, minimizing unnecessary spill, maximizing hydropower generation release, keeping water storage levels high for efficient hydroelectric turbine operation. This optimization model is a large scale mixed integer programming problem that consists of 3.920 integer variables and 68.658 by 132.384 node-arc incidence matrix for 28 years of data. In order to handle the enormous amount of data generated by a big mathematical model, the utilization of DBMS (data base management system)seems to be inevitable. It has been tested with the Han River multi-reservoir system in Korea, which consists of 2 large multipurpose dams and 3 hydroelectric dams. We demonstrated successfully that there is a good chance of saving substantial amount of water should it be put to use in real time with a good inflow forecasting system.