• Journal of Internet Computing and Services
• /
• v.11 no.5
• /
• pp.9-17
• /
• 2010

During the last decade, Internet protocol television(IPTV), broadcasting of multimedia services using well understood Internet technologies, is a fast spreading technology for distributing multimedia content to consumers. As IPTV services advance, an increasing user demand and tremendous content volume of multimedia content cause some difficulties in network resource management. In this paper, we propose an improved load balancing algorithm for video-on-demand(VoD) service. Unlike existing algorithms, the proposed algorithm considers user's behaviors for VoD service, and determines the most efficient allocation of VoD requests by estimating expected server load and expected user waiting time.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2002.04a
• /
• pp.35-40
• /
• 2002

A numerical analysis based on two-dimensional and three-dimensional incompressible Navier-Stokes equations has been carried out for double-circular-arc compressor cascades and the results are compared with available experimental data at various incidence angles. The 2-D and 3-D computational codes based on SIMPLE algorithm adopt pressure weighted interpolation method for non-staggered grid and hybrid scheme for the convertive terms. Turbulence modeling is very important for prediction of cascade flows, which are extremely complex with separation and reattachment by adverse pressure gradient. In this paper k-$\varepsilon$ turbulence model with wall function is used to increase efficiency of computation times.

• The Journal of the Korea Contents Association
• /
• v.13 no.8
• /
• pp.36-43
• /
• 2013

Fully homomorphic encryption is a cryptography system in which coded data can be searched and statistically processed without decryption. Fully homomorphic encryption has accelerated searching speed by minimizing time spent on encryption and decryption. In addition, it is also known to prevent leakage of any data decoded for statistical reasons. Also, it is expected to protect personal information stored in the cloud computing environment which is becoming commercialized. Since the 1970s when fully homomorphic encryption was first introduced, it has been researched to develop the algorithm that satisfy effectiveness and functionality. We will take the reader through a journey of these developments and provide a glimpse of the exciting research directions that lie ahead.

• Journal of IKEEE
• /
• v.11 no.4
• /
• pp.322-330
• /
• 2007

Recent advances in wireless networks and low-cost, low-power design have led to active research in large-scale networks of small, wireless, low power sensors and actuators, In large-scale networks, lots of timing-synchronization protocols already exist (such as NTP, GPS), In ad-hoc networks, especially wireless sensor networks, it is hard to synchronize all nodes in networks because it has no infrastructure. In addition, sensor nodes have low-power CPU (it cannot perform the complex computation), low batteries, and even they have to have active and inactive section by periods. Therefore, new approach to time synchronization is needed for wireless sensor networks, In this paper, I propose Energy-Efficient Time Synchronization (EETS) protocol providing network-wide time synchronization in wireless sensor networks, The algorithm is organized two phase, In first phase, I make a hierarchical tree with sensor nodes by broadcasting "Level Discovery" packet. In second phase, I synchronize them by exchanging time stamp packets, And I also consider send time, access time and propagation time. I have shown the performance of EETS comparing Timing-sync Protocol for Sensor Networks (TPSN) and Reference Broadcast Synchronization (RBS) about energy efficiency and time synchronization accuracy using NESLsim.

• Journal of Korea Game Society
• /
• v.14 no.6
• /
• pp.59-68
• /
• 2014

Memory bandwidth requirements of UHD (Ultra High Definition $4096{\times}2160$) game scenes have been much more increasing. This paper presents a lossless DPCM-GR based compression algorithm using CUDA for solving the memory bandwidth problem without sacrificing image quality, which is modified from DDPCM-GR [4] to support bit parallel pipelining. The memory bandwidth efficiency increases because of using the shared memory of CUDA. Various asynchronous transfer configurations which can overlap the kernel execution and data transfer between host and CUDA are implemented with the page-locked host memory. Experimental results show that the maximum 31.3 speedup is obtained according to CPU time. The maximum 30.3% decreases in the computation time among various configurations.

• Journal of Advanced Marine Engineering and Technology
• /
• v.34 no.6
• /
• pp.906-913
• /
• 2010

Recently, lots of researches are carried out to develop hybrid power generation system for ocean facility. Normally, the stand-alone type power system is used in the ocean facility, which is influenced by weather condition. To improve the efficiency, a various charging strategy with switching algorithm has been studied. In this paper, the power system using multi-level type is proposed. The simulation results based on actual data of photovoltaic and wave hybrid power system are presented. The results show that the rate of charging time is increased 5~11% and 7~47% respectively to compare the conventional technique.

• Journal of Broadcast Engineering
• /
• v.13 no.3
• /
• pp.415-418
• /
• 2008

Some embedded microprocessors do not have an FPU(Floating Point Unit) due to a circuit complexity and power consumption. The performance speed of MPEG-4 AAC decoder on this hardware environment would be slower than corresponding speed for playing back of the decoded results. Therefore, irritating and high-pitched noises are interleaved in the original the audio data. So, in order to play MPEG-4 AAC file on such PDA, a new algorithm that transforms floating-point arithmetic to one with integers, is needed. We have developed a transformation algorithm from floating-point operation to integer operation and implemented the PDA's AAC Player. We also show the efficiency of our proposed method with the experimental results.

• Journal of the Korean Society for information Management
• /
• v.23 no.4 s.62
• /
• pp.215-231
• /
• 2006

Recently there are many bibliometric studies attempting to utilize Pathfinder networks(PFNets) for examining and analyzing the intellectual structure of a scholarly field. Pathfinder network scaling has many advantages over traditional multidimensional scaling, including its ability to represent local details as well as global intellectual structure. However there are some limitations in PFNets including very high time complexity. And Pathfinder network scaling cannot be combined with cluster analysis, which has been combined well with traditional multidimensional scaling method. In this paper, a new method named as Parallel Nearest Neighbor Clustering (PNNC) are proposed for complementing those weak points of PFNets. Comparing the clustering performance with traditional hierarchical agglomerative clustering methods shows that PNNC is not only a complement to PFNets but also a fast and powerful clustering method for organizing informations.

• Journal of KIISE:Software and Applications
• /
• v.34 no.6
• /
• pp.530-538
• /
• 2007

Most existing deductive engines study for optimization of TBox based on Tableaux algorithm. However, in order to deduce mass-storing ABox in reality, it can't be decided in finite time. Therefore, for the efficiency of the deductive engine, there needs to be reasoning technique optimized for ABox. This paper uses the method that changes OWL-DL based Ontology to the form of Rule like Datalog in order to interlock store device such as RDBMS. Ultimately, it tries to in circumstance of real world. Therefor, using Axiom that OWL holds, it suggests reasoning method that applies rules including datatype.

• The Transactions of the Korea Information Processing Society
• /
• v.2 no.3
• /
• pp.390-396
• /
• 1995

One of the advantages of computer graphics is that it enables to view an object on different viewpoints and different angles. Therefore, a computer graphics system should be able to rotate an arbitrary object by an arbitrary angle about an arbitrary axis. This is usually done by rotating vertices that represent an object and connecting them. Hence an image may have many vertices, it is important to be able to rotate each of them quickly. Therefore, this paper is interested in a rotation matrix computation method that consists of the smallest number of computational steps. This pater proposes an algorithm that computes rotation matrix to rotate a 3 dimensional image about an arbitrary axis quickly.