• Journal of Information Processing Systems
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• v.10 no.2
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• pp.271-282
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• 2014

The advancement of knowledge society has enabled the social network community (SNC) to be perceived as another space for learning where individuals produce, share, and apply content in self-directed ways. The content generated within social networks provides information of value for the participants in real time. Thus, this study proposes the social network community activity-based content model (SoACo Model), which takes SNC-based activities and embodies them within learning objects. The SoACo Model consists of content objects, aggregation levels, and information models. Content objects are composed of relationship-building elements, including real-time, changeable activities such as making friends, and participation-activity elements such as "Liking" specific content. Aggregation levels apply one of three granularity levels considering the reusability of elements: activity assets, real-time, changeable learning objects, and content. The SoACo Model is meaningful because it transforms SNC-based activities into learning objects for learning and teaching activities and applies to learning management systems since they organize activities -- such as tweets from Twitter -- depending on the teacher's intention.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.11 no.2
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• pp.95-102
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• 2011

In this paper, a Mobile Continuous Query Processing System (MCQPS) is designed to solve problems related to database hoarding, maintenance of shared data consistency, and optimization of logging. These problems are caused by weak connectivity and disconnection of wireless networks inherent in mobile database systems under mobile client-server environments. We show the superiority of the proposed MCQPS by comparing its performance to the Client-Intercept-Server (C-I-S) model. In addition, several experimental results show the effectiveness of our proposed indexing structure and methodology for real-time continuous queries.

• Journal of Information Processing Systems
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• v.19 no.6
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• pp.817-829
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• 2023

Variable wireless channel is a big challenge for real-time video applications, and the rate adaptation of realtime video streaming becomes a hot topic. Intra-video coding is important for high-quality video communication and industrial video applications. In this paper, we proposed a novel adaptive scheme for real-time video transmission with intra-only coding over a wireless network. The key idea of this scheme is to estimate the instantaneous remaining capacity of the network to adjust the quality of the next several video frames, which not only can keep low queuing delay and ensure video quality, but also can respond to bandwidth changes quickly. We compare our scheme with three different schemes in the video transmission system. The experimental results show that our scheme has higher bandwidth utilization and faster bandwidth change response, while maintaining low queuing delay.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.937-940
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• 2007

오늘날 대부분의 임베디드 시스템에서 사용하는 uClinux에서 기본적으로 프로세스가 이용할 수 있는 범위의 시스템 클럭은 10m/s 이상이다. 기존에는 무리하게 시스템 클럭의 속도를 무리하게 높여 더 높은 정밀도를 요구하는 프로세스를 처리해 왔다. 이는 시스템 리소스를 많이 사용함과 동시에 타이머 인터럽트를 처리하는 오버헤드도 상대적으로 증가하여 전체적으로 시스템의 성능과 안정성에 좋지 못했다. 이에 본 논문에서는 uClinux기반의 임베디드 장치와 Real-Time Clock(RTC)모듈과의 인터페이스 최적화 방안에 관하여 제안한다. 이로써 시스템 클럭을 사용하지 않고, RTC 자체의 인터럽트를 사용해서 작업을 진행해 나가기 때문에 시스템 리소스를 적게 사용하며, 시스템의 성능에 영향을 적게 준다. 또한 알고리즘적인 최적화를 사용 코드최적화를 사용하여 임베디드 시스템에서 가장 효율적으로 관리해야할 리소스인 메모리를 절약, 기존의 방식과 차별을 두었다.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.1195-1198
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• 2007

In this paper we study the problem of real time support in wireless sensor networks and propose a Real time Geographic Routing Protocol (ReGeo) which routes a packet towards the destination based on a compromise between distance and queue count to reduce traffic concentration wherever it has been determined to be too high and uses Gradient Table to store the route satisfying the delay constraints. We describe our prototype implementation of ReGeo Routing in TOSSIM - a TinyOS mote simulator. The simulation results show that the proposed routing protocol not only increases the packet delivery ratio but also keeps overall End to End Delay under a bounded value.

• The KIPS Transactions:PartC
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• v.8C no.5
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• pp.525-534
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• 2001

Generally, compression and encryption procedures are performed independently in lossless image compression and encryption. When compression is followed by encryption, the compressed-stream should have the property of randomness because its entropy is decreased during the compression. However, when full data is compressed using image compression methods and then encrypted by encryption algorithms, real-time processing is unrealistic due to the time delay involved. In this paper, we propose to combine compression and encryption to reduce the overall processing time. It is method decomposing gray-scale image by means of quadtree compression algorithms and encrypting the structural part. Moreover, the lossless compression ratio can be increased using a transform that provides an decorrelated image and homogeneous region, and the encryption security can be improved using a reconstruction of the unencrypted quadtree data at each level. We confirmed the increased compression ratio, improved encryption security, and real-time processing by using computer simulations.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.171-174
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• 2006

A large number of service providers in countries all over the world have established GNSS reference station networks in the last years and are using network software today to provide a correction stream to the user as a routine service. In current GNSS network processing, all the geometric related information such as ionospheric free carrier phase ambiguities from all stations and satellites, tropospheric effects, orbit errors, receiver and satellite clock errors are estimated in one centralized Kalman filter. Although this approach provides an optimal solution to the estimation problem, however, the processing time increases cubically with the number of reference stations in the network. Until now one single Personal Computer with Pentium 3.06 GHz CPU can only process data from a network consisting of no more than 50 stations in real time. In order to process data for larger networks in real time and to lower the computational load, a federated filter approach can be considered. The main benefit of this approach is that each local filter runs with reduced number of states and the computation time for the whole system increases only linearly with the number of local sensors, thus significantly reduces the computational load compared to the centralized filter approach. This paper presents the technical aspect and performance analysis of the federated filter approach. Test results show that for a network of 100 reference stations, with the centralized approach, the network processing including ionospheric modeling and network ambiguity fixing needs approximately 60 hours to process 24 hours network data in a 3.06 GHz computer, which means it is impossible to run this network in real time. With the federated filter approach, only less than 1 hour is needed, 66 times faster than the centralized filter approach. The availability and reliability of network processing remain at the same high level.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.397-398
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• 2007

• The Transactions of the Korea Information Processing Society
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• v.7 no.12
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• pp.3804-3814
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• 2000

This paper presents an efficient implementation of a run-time monitor which checks the satisfaction of the timing constraints of real-time object-oriented programs based on a real-time object model called TMO(Time-triggered Messagedtriggered Object). An execution environment of TMO programs on Windows as, WTMOS(Windows TMO System) has been utilized for the implementation and an experimental application for thermostatic control has been developed to analyze the performance of the run-time monitor. We suggest a methodology for application programmers to specify the target methods with the monitoring conditions and an implementation technique which incurs the small cost by effectively distributing the functions of the monitor into the WTMOS and a TMO object.

• Journal of Broadcast Engineering
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• v.6 no.2
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• pp.169-176
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• 2001

Most of the previous video watermarking algorithms cannot be supported by real-time video processing. The maul reason is that in order to develop a robust algorithm the watermarking technique requires a very high computational cost when embedding and extracting the watermark in various frequency domains. Previous embedding methods simultaneously try to compress a video by MPEG and embed a watermark supporting real-time processing. However, In this paper, our proposed algorithm can support real-time processing in both spatial and frequency domains. First. the watermark is created on the courier transform domain, and next is inverse-Fourier-transformed ; then, we directly embed it into the video frame In the spatial domain. This procedure does not require a lot of the computational cost during embedding because of the spatial domain processing. Also, it is possible to support a video stream service and a very robust algorithm from MPEG compression and various geometric attacks.