• Journal of Korea Society of Industrial Information Systems
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• v.4 no.4
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• pp.1-6
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• 1999

When continuous media are transmitted over the communication networks, asynchrony which can not maintain temporal relationships among packets my occur due to a random transit delay. There exist two types of synchronization schemes ; for guaranteed or non-guaranteed resource networks. The former which applies a resource reservation technique maintains delay characteristics however, the latter supply a best-effort service. In this paper, I propose a intra-media synchronization scheme to transmit continuous media on general networks not guaranteeing a bounded delay time. The scheme controls transmission times of the packets by estimating next delay time with the delay distribution So, the arriving packets my be maintained within a limited delay boundary, and playout will be performed after buffering to smoothen small delay variations. To prevent network congestion and maintain minimum quality of service the transmitter performs media scaling-down by dropping the current packet when informed excessive delay from the receiver.

• Proceedings of the Korean Society for Cognitive Science Conference
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• 2010.05a
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• pp.37-41
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• 2010

The previous investigations of electroencephalogram (EEG) activity in the memory retrieval tasks demonstrated that event-related potentials (ERP) during recollection showed different durations and the peak levels from those without recollection. However, it has been unknown that recollection in memory retrieval also modulates high-frequency brain rhythms as well as establishes large-scale synchronization across different cortical areas. In this study, we examined the spectral components of the EEG signals, especially the gamma bands (20-80Hz), measured during the memory retrieval tasks. Specifically, we focused on two major spectral components: first, we evaluated the temporal patterns of the power spectral density before and after the onset of the memory retrieval task; second, we estimated phase synchrony between all possible pairs of EEG channels to evaluate large-scale synchronization. Fourteen healthy subjects performed the memory retrieval task in the virtual reality environment where they selected whether or not t he present item was seen in the previous training period. When the subjects viewed the unseen items, the middle gamma power (40-60Hz) appeared to increase 200-500ms after stimulus onset while the low gamma power (20Hz) was suppressed all the way through the post-stimulus period 150ms after onset. The degree of phase synchronization in this low gamma level, however, increased when the subjects fetched the item from memory. This suggests that phase synchrony analysis might reveal different aspects of the memory retrieval process than the gamma power, providing additional information to the inference on the brain dynamics during memory retrieval.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.171-174
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• 2008

As the mobile devices and the wireless networks have high-performance capabilities, it is possible to synchronize the spatio-temporal data of a server with the spatio-temporal data of a mobile device which are collected at a field. However, since the server process the synchronization which the model device requests the whole synchronizations of mass mobile devices take long time. In this paper, we propose the scheme to Process concurrently the synchronizations of mobile devices which does not conflict with others using the scheme of a multi-queue.

• The KIPS Transactions:PartB
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• v.10B no.1
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• pp.111-118
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• 2003

The SMIL specification that is recently approved by the W3C and is meant to help deliver multimedia content to the Web, is widely used in these days and they have continuously emerged tools or softwares related with that. In this paper, I propose an algorithm to convert temporal scripts of RASP that is an experimental toolkit for computer animation that promotes interaction-based programming over time into a SMIL document. For making better use of SMIL documents, we can improve reusability of animation components. And, main contribution of this paper is that it verifies the sequence diagram generated for synchronization of documents by reconverting SMIL from UML sequence diagram.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.1
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• pp.108-116
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• 2005

Synchronizations of intra${\cdot}$intermedia for the lecture presentation in distributed multimedia environments are difficult to guarantee accurate temporal relationship between media, due to the asynchronous errors such as the delay or loss of transferred data or the transmission characteristics of each media. The jitter phenomenon occurs when the network delay has the media arrival rate abnormal because the intra-media synchronization reflects the presentation rate. And the cumulative effective of jitters on a per media stream basis results in a skew. This phenomenon cause confusion to contents recognition of learners due to network delay and can not provide effective interaction of sender and receiver in the distance education. Therefore, this paper can be solution to problems due to network delay by maintaining the requirements of temporal relationship between more than one media. And this paper enables to suggest the inter-media synchronization method that is subject to be influenced by presentation rate, and to implement lecture presentation system for distance education.

• Journal of KIISE:Databases
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• v.27 no.2
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• pp.185-198
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• 2000

Recently the technological advance in the hardware dealing with multimedia data as well as the explosive increase of the volume of multimedia data bring about new interest in the use of multimedia presentations in many application domains. To use multimedia presentations efficiently, the integration of multimedia presentations into DBMS is necessary. This paper presents a multimedia presentatation query language based on contents and query processing techniques. Presently, multimedia presentation authoring tools denote a multimedia presentation using a presentation graph which is a DAG. A Node in the graph is a same type of media stream and edges denote a play-out order and a synchronization way among nodes. The contents of presentations graphs are the information of each stream, the sequential order of the information inside each stream and the play-out order among the streams. GCalculus/S is a calculus-based query language and can deal with the contents of a presentation graph and physical characteristics of multimedia data. It expresses the sequential order of information inside each stream and the play-out order of streams of a presentation graph using temporal operators Next, Connected and Until. O-Algebra, which is object algebra, is extended to process GCalculus/S queries.

• Journal of the Korean Institute of Intelligent Systems
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• v.19 no.1
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• pp.40-47
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• 2009

Recently, dynamic proxy caching has been proposed on the distributed environment so that media objects by user's requests can be served directly from the proxy without contacting the server. However, it makes caching challenging due to multimedia large sizes, low latency and continuous streaming demands of media objects. To solve the problems caused by streaming demands of media objects, this paper has been proposed the grouping scheme with fuzzy filtering based on partition and mapping. For partition and mapping, this paper divides media block segments into fixed partition reference block(R$_f$P) and variable partition reference block(R$_v$P). For semantic relationship, it makes fuzzy relationship to performs according to the fixed partition temporal synchronization(T$_f$) and variable partition temporal synchronization(T$_v$). Simulation results show that the proposed scheme makes streaming service efficiently with a high average request response time rate and cache hit rate and with a low delayed startup ratio compared with other schemes.

• Journal of KIISE:Computing Practices and Letters
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• v.9 no.3
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• pp.266-277
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• 2003

Every conceptual temporal rat relationship can be described using one of seven relations (before, meets, overlaps, during, starts, finishes, and equals ). The conceptual representation provides an efficient means for our multimedia authoring system to automatically fill in the necessary timing details. We developed a multimedia Presentation authoring system that supports a mechanism for conceptually representing the temporal relations of different media. Among the many editors that make up our system, the temporal relation editor provides users with an intuitive mechanism for representing the conceptual flow of a presentation by simple and direct graphical manipulations. Our system is based on the SMIL(Synchronized Multimedia Integration Language). The conceptual temporal relation editor and other editors of our system exchange their information in real-time and automatically generate SMIL codes through the SMIL Object Manager. Our system uses TRN(Temporal Relation Network) as its internal multimedia presentation representation. The TRN corresponds exactly to the structure seen in the graphical representation of the presentation. A parallel relationship found in a TRN can be collapsed into a single synchronization block. This facilitates the determination of the playing time of each component and can be the basic unit for reusability of already prepared blocks of presentation code.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.39 no.6
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• pp.53-67
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• 2002

The multimedia synchronization is one of the key issues to be resolved in order to provide a good quality of multimedia related services, such as Video on Demands(VoD), Lecture on Demands(LoD), and tele-conferences. In this paper, we introduce an adaptive multimedia synchronization algorithm using the level of buffers and load of servers, which are modeled and analyzed by ExSpect, a Petri net based simulation tool. In the proposed algorithm, the audio and video buffers are divided to 5 different levels, and the pre-defined play-out speed controller tries to make the buffer level to be normal in different temporal relations between multimedia streams using buffer levels and server loads. Because each multimedia packet is played by the pre-defined play-out speed, the media data can be reproduced within the permissible limit of errors while preserving the level of buffers to be normal. The proposed algorithm is able to handle and support various communication restrictions between providers and users, and offers little jitter play-out to many users in networks with the limited transmission capability. The performance of the developed algorithm is analyzed in various network conditions using a Petri net simulation tool.

• Journal of Biomedical Engineering Research
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• v.39 no.2
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• pp.94-102
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• 2018

It is known that gamma-band activity (GBA) and phase synchrony (GBPS) are induced by emotional visual stimuli. However, the characteristics of GBA and GBPS according to different emotional states have not been identified. The purpose of this study is to investigate the changes in gamma-band neuronal synchronization induced by positive and negative emotional visual stimuli using electroencephalograms (EEGs). Thirteen healthy male subjects have participated in the experiment. The induced spectral power in gamma-band was the highest for negative stimuli, and the lowest for neutral stimuli in 300-2,000 ms after the stimulus onset. The inter-regional phase synchronization in gamma-band was increased in 500-2,000 ms, mainly between the bilateral frontal regions and the parieto-occipital regions. Larger number of significant connections were found by negative stimuli compared to positive ones. Judging from temporal and spatial characteristics of the gamma-band activity and phase synchrony increases, the results may imply that affective visual stimuli cause stronger memory encoding than non-emotional stimuli, and this effect is more significant for negative emotional stimuli than positive ones.