• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.4
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• pp.131-140
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• 2012

The shortest path search algorithm of navigation is generally based on Dijkstra algorithm and considers only the distance using the weight. Dijkstra algorithm based on the distance mainly ought to perform the 'number of nodes 1' and requires a lot of memory, for it is to start from the starting node and to decide the shortest path for all the nodes. Also, it searches only the same identical path in case of any bottleneck due to an accident nearby, since it is based only on the distance, and hence does not have a system that searches the detour road. In order to solve this problem, this paper considers only the travelling time per road (travelling speed * distance), without applying speed criteria (smoothness, slow speed, stagnation and accident control) or road class (express road, national road and provincial road). This provides an advantage of searching the detour, considering the reality that there are differences in time take for the car to travel on different roads with same distance, due to any accident, stagnation, or repair construction. The suggested algorithm proves that it can help us to reach the destination within the shortest time, making a detour from any congested road (outbreak) on providing an information on traveling time continuously(real-time) even though there is an accident in a particular road.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.4
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• pp.41-49
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• 2010

This paper proposes a new high speed SHA-1 architecture using multiple unfolding and pre-computation techniques. We unfolds iterative hash operations to 2 continuos hash stage and reschedules computation timing. Then, the part of critical path is computed at the previous hash operation round and the rest is performed in the present round. These techniques reduce 3 additions to 2 additions on the critical path. It makes the maximum clock frequency of 118 MHz which provides throughput rate of 5.9 Gbps. The proposed architecture shows 26% higher throughput with a 32% smaller hardware size compared to other counterparts. This paper also introduces a analytical model of multiple SHA-1 architecture at the system level that maps a large input data on SHA-1 block in parallel. The model gives us the required number of SHA-1 blocks for a large multimedia data processing that it helps to make decision hardware configuration. The hs fospeed SHA-1 is useful to generate a condensed message and may strengthen the security of mobile communication and internet service.

• Journal of the Korea Society of Computer and Information
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• v.16 no.12
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• pp.175-185
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• 2011

The threshold level of a receiver is analyzed for the simplification of system and the improvement of upstream data ratios in optical subscriber network of which the upstream date rate and the optical transmitted power are changed to meet the requested BER (Bit Error Rate) defined per interactive multimedia services. In asynchronous optical subscriber network of which the upstream to downstream data ratios are 1:1/2, 1:1/4, 1:1/8 and 1:1/16 with manchester coded downstream and NRZ (Non Return to Zero) downstream re-modulation, the BER performance is theoretically analyzed and it is performed by simulation with MATLAB according to the four types of downstream data for four models. The results have shown that in the cases which the upstream to downstream data ratios are 1:1/4, 1:1/8 and 1:1/16 the conventional receiver with threshold level of 1/2 can be applied regardless of average received optical powers and the BER is not much deteriorated compared with using the optimal threshold level. In the case that the upstream to downstream data ratio is 1:1/2 the threshold level in an optical receiver could be fixed at 1/3 and the BER is not much deteriorated compared with using the optimal threshold level as the average received optical power increases.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.46-54
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• 2018

The Internet of Things (IoT) is an environment in which various devices provide services to users through communications. Because of the nature of the IoT, data are stored and distributed in heterogeneous information systems. In this situation, IoT end applications should be able to access data without having information on where the data are or what the type of storage is. This mechanism is called Service Discovery (SD). However, some problems arise, since the current SD architectures search for data in physical devices. First, turnaround time increases from searching for services based on physical location. Second, there is a need for a data structure to manage devices and services separately. These increase the administrator's service configuration complexity. As a result, the device-oriented SD structure is not suitable to the IoT. Therefore, we propose an SD structure called Name-based Service-centric Service Discovery (NSSD). NSSD provides name-based centralized SD and uses the IoT edge gateway as a cache server to speed up service discovery. Simulation results show that NSSD provides about twice the improvement in average turnaround time, compared to existing domain name system and distributed hash table SD architectures.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.5B
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• pp.449-455
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• 2006

Due to advance in multimedia applications and integrated Internet services, the optical access networks have been actively studied. In particular, Ethernet passive optical network (EPON) has received much attention due to high bandwidth provision with low cost. In EPON system, the data transmission is carried out in two directions: downstream (from OLT to ONU) and upstream (from ONU to OLT). The downstream data is broadcasted to every ONUs, while the upstream data is point-to-point transmitted between each ONU and OLT, where the uplink is shared by all ONUs in the form of TDMA. The bandwidth allocation algorithm is required to efficiently manage the bandwidth on the uplink. The limited algorithm was proposed to enhance the capability of dynamic bandwidth allocation. In this paper, we propose the adaptive limited algorithm to enhance the shortcomings of limited algorithm. The adaptive limited algorithm enhances the dynamics on bandwidth allocation, and at the same time controls the fairness on packet delay. Through the computer simulations, it is shown that the adaptive limited algorithm achieves high dynamic on bandwidth allocation, maintains a good fairness on packet delay between ONUs, and keeps the fairness on the bandwidth on the demand basis.

• Journal of KIISE:Software and Applications
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• v.32 no.10
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• pp.1003-1012
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• 2005

The most significant difference of embedded systems from general purpose systems is that embedded systems are allowed to use only limited resources including battery and memory. Especially, the number of applications increases which deal with multimedia data. In those systems with high data computations, the delay of memory access is one of the major bottlenecks hurting the system performance. As a result, many researchers have investigated various techniques to reduce the memory access cost. Most programs generally have locality in memory references. Temporal locality of references means that a resource accessed at one point will be used again in the near future. Spatial locality of references is that likelihood of using a resource gets higher if resources near it were just accessed. The latest embedded processors usually adapt cache memory to exploit these two types of localities. Processors access faster cache memory than off-chip memory, reducing the latency. In this paper we will propose the enhanced dynamic allocation technique for structure-type data in order to eliminate unused memory space and to reduce both the cache miss rate and the application execution time. The proposed approach aggregates fields from multiple records dynamically allocated and consecutively remaps them on the memory space. Experiments on Olden benchmarks show $13.9\%$ L1 cache miss rate drop and $15.9\%$ L2 cache miss drop on average, compared to the previously proposed techniques. We also find execution time reduced by $10.9\%$ on average, compared to the previous work.

• Journal of KIISE:Computer Systems and Theory
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• v.30 no.12
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• pp.756-771
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• 2003

Digital Video Library System which manages a large amount of multimedia information requires efficient and effective retrieval methods. In this paper, we propose and implement a new video search and retrieval algorithm that compares the query video shot with the video shots in the archives in terms of foreground object, background image, audio, and its context. The foreground object is the region of the video image that has been changed in the successive frames of the shot, the background image is the remaining region of the video image, and the context is the relationship between the low-level features of the adjacent shots. Comparing these features is a result of reflecting the process of filming a moving picture, and it helps the user to submit a query focused on the desired features of the target video clips easily by adjusting their weights in the comparing process. Although the proposed search and retrieval algorithm could not totally reflect the high level semantics of the submitted query video, it tries to reflect the users' requirements as much as possible by considering the context of video clips and by adjusting its weight in the comparing process.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.5
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• pp.555-564
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• 2016

This paper proposes a time slot allocation scheme for military patrol environments. This proposal comes from analysis of traffic properties in a military patrol environment. In the near future, robots are expected to explore enemy grounds and measure threat, taking the place of human patrol. In order to control such robots, control messages must be extremely accurate. One mistake from the control center could cause a tragedy. Thus, high reliability must be guaranteed. Another goal is to maintain a continual flow of multimedia data sent from patrol robots. That is, QoS (Quality of Service) must be guaranteed. In order to transmit data while fulfilling both attributes, the per-path based centralized TDMA slot allocation scheme is recommended. The control center allocates slots to robots allowing synchronization among robots. Slot allocation collisions can also be avoided. The proposed scheme was verified through the ns-3 simulator. The scheme showed a higher packet delivery ratio than the algorithm in comparison. It also performed with shorter delay time in the downlink traffic transmission scenario than the algorithm in comparison.

• Cartoon and Animation Studies
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• s.48
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• pp.69-84
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• 2017

In order to display various art works such as media art in a multi-display environment, it is necessary to consider contents arrangement. The advantage of having a 1: N or N: N layout instead of a 1: 1 or N: 1 layout between display and content, but a more complex scheme of how to do spatial and temporal layout in multi-display Is required. In order to distribute contents, existing media server solution or programming-based multimedia production software is used. However, it takes much time to rearrange or modify the contents, and it is not easy to modify the contents. Therefore, It is difficult to place content in the environment. In order to solve this problem, various approaches are needed from research on content placement method to development of content placement software that improves the existing method. However, analysis on systematic content placement type supporting it, or interface There is also no access to. In this study, we have summarized the requirements for designing the interface for each type with the aim of making it possible to utilize previously analyzed content layout types in various display activities such as media art in multi - display environment. The requirements of each type of interface were derived based on spatial arrangement and temporal layout type which are most distinguished when content is placed. The contents of the interface requirements are summarized as follows: We expect to be a cornerstone for system development.

• KDI Journal of Economic Policy
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• v.32 no.3
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• pp.101-137
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• 2010

This paper defines markets relating to each paid broadcasting service by applying the test method of critical sales loss to the results of survey to the paid service subscribers. The result confirms the existence of a meaningful competitive relationship--in terms of the Competition Law--among all paid broadcasting services included in this study, or at least analog cable broadcasting, digital cable broadcasting, and real time IPTV(Internet Protocol TV) service. This indicates that current regulations which are being applied to cable TV, satellite broadcasting, and IPTV are actually discriminatory. Based on these analysis results, this paper suggests that the main attention for the improvement of regulations should be focused on regulations which are differently applied to different paid service providers. In particular, Article 20 in the Internet Multimedia Broadcasting Law is interpreted as defining the real-time IPTV as an independent market, thereby having leeway to harm fair competition among different paid service providers. Therefore, that article needs to change to give the right of equal access to contents to all the competing paid service providers. Furthermore, to put teeth in the contents equal access rule, most popular pay channels need to be designated as target contents of the rule. As for the market-share limitation regulations, the paper suggests that an upper limit on the market share should be set based on the total number of subscribers of all the competing paid services and the same limit applied to all the competing paid service providers.