• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.7 no.6
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• pp.12-20
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• 2008

Recent wireless communication technologies are envisioned as an innovative alternative to solve transportation problems. On ad hoc networks, as a wireless communication technology, nodes can communicate data without any infrastructure. In particular, vehicular ad hoc networks (VANETs), a specific ad hoc network applied to vehicles, enable vehicles equipped with a communication device to form decentralized traffic information systems in which vehicles share traffic information they experienced. This study investigated traffic information dissemination in a VANET-based traffic information system. For this study, an integrated transportation and communications simulation framework was developed, and experiments were conducted with real highway networks and traffic demands. The results showed that it took 3 minutes in the low traffic density situations (10 vehicle/lane.km) and 43 seconds in the high traffic density condition (40 vehicle/lane.km) to deliver traffic information of 5km away with 10% market penetration rate. In uncongested traffic conditions, information seems to be disseminated via equipped vehicles in the opposite direction. In congested traffic conditions, the sufficient availability of equipped vehicles traveling in the same direction reduces the chance to use vehicles in the opposing direction even though it is still possible.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.1
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• pp.191-197
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• 2013

Conventional CT and MRI scans produce cross-section slices of body that are viewed sequentially by radiologists who must imagine or extrapolate from these views what the 3 dimensional anatomy should be. By using sophisticated algorithm and high performance computing, these cross-sections may be rendered as direct 3D representations of human anatomy. The 2D medical image analysis forced to use time-consuming, subjective, error-prone manual techniques, such as slice tracing and region painting, for extracting regions of interest. To overcome the drawbacks of 2D medical image analysis, combining with medical image processing, 3D visualization is essential for extracting anatomical structures and making measurements. We used the gray-level thresholding, region growing, contour following, deformable model to segment human organ and used the feature vectors from texture analysis to detect harmful cancer. We used the perspective projection and marching cube algorithm to render the surface from volumetric MR and CT image data. The 3D visualization of human anatomy and segmented human organ provides valuable benefits for radiation treatment planning, surgical planning, surgery simulation, image guided surgery and interventional imaging applications.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.6
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• pp.167-173
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• 2016

Compressed Sensing(CS) is the theory that can recover signals which are sampled below the Nyquist sampling rate to original analog signals. In this paper, we propose the estimation algorithm of ultrasonic attenuation coefficients in the frequency domain using CS. While most estimation algorithms transform the time-domain signals into the frequency-domain using the Fourier transform, the proposed method directly utilize the spectral information in the recovery process by the basis matrix without the completely recovered signals in the time domain. We apply three transform bases for sparsifying and estimate the attenuation coefficients using the Centroid Downshift method with Dual-reference diffraction compensation technique. The estimation accuracy and execution time are compared for each basis matrix. Computer simulation results show that the DCT basis matrix exhibits less than 0.35% estimation error for the compressive ratio of 50% and about 6% average error for the compressive ratio of 70%. The proposed method which directly extracts frequency information from the CS signals can be extended to estimating for other ultrasonic parameters in the Quantitative Ultrasound (QUS) Analysis.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.11 s.353
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• pp.85-94
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• 2006

Simple-relay aided resource allocation (SRARA) schemes are incorporated with throughput guarantee scheduling (TGS) in IEEE 802.16 type TDD-OFDMA downlink to enhance service coverage, where the amount of resources at each relay is limited due to either its available power which is much smaller than base station (BS) power or the required overhead The performance of SRARA schemes is evaluated with both proportional fair (PF) and TGS schedulers at 64 kbps and 128 kbps user throughput requirements. For SRARA with RSs of relatively lower power, a scheme putting total power into only one subchannel shows larger coverage than when both subchnnels are used in a manner of equal power allocation, while the RS with evenly power-allocated two subchannels could provide larger coverage gain for a relatively higher power. In a lower target (64kbps), more improvement comes from relay scheme rather than scheduler design. For a relatively higher level (128 kbps), it comes from scheduler design rather than relay.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.37 no.5
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• pp.54-63
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• 2000

We present a multi-resolution block matching algorithm (BMA) for fast motion estimation At the coarsest level, a motion vector (MV) having minimum matching error is chosen via a full search, and a MV with minimum matching error is concurrently found among the MVs of the spatially adjacent blocks Here, to examine the spatial MVs accurately, we propose an efficient method for searching full resolution MV s without MV quantization even at the coarsest level The chosen two MV s are used as the initial search centers at the middle level At the middle level, the local search is performed within much smaller search area around each search center If the method used at the coarsest level is adopted here, the local searches can be done at integer-pel accuracy A MV having minimum matching error is selected within the local search areas, and then the final level search is performed around this initial search center Since the local searches are performed at integer-pel accuracy at the middle level, the local search at the finest level does not take an effect on the overall performance So we can skip the final level search without performance degradation, thereby the search speed increases Simulation results show that in comparison with full search BMA, the proposed BMA without the final level search achieves a speed-up factor over 200 with minor PSNR degradation of 02dB at most, under a normal MPEG2 coding environment Furthermore, our scheme IS also suitable for hardware implementation due to regular data-flow.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.8
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• pp.66-75
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• 2016

Due to aggressive scaling of device sizes and reduced noise margins, physical defects caused by aging and process variation are continuously increasing. Additionally, with scaling limitation of metal wire and the increasing of communication volume, fault tolerant method in manycore network-on-chip (NoC) has been actively researched. However, there are few researches investigating reliability in NoC with voltage-frequency-island (VFI) regime. In this paper, we propose a table-based routing technique that can communicate, even if link failures occur in the VFI NoC. The output port is alternatively selected between best and the detour routing path in order to improve reliability with minimized hardware cost. Experimental results show that the proposed method achieves full coverage within 1% faulty links. Compared to $d^2$-LBDR that also considers a routing method for searching a detour path in real time, the proposed method, on average, produces 0.8% savings in execution time and 15.9% savings in energy consumption.

• Journal of KIISE:Information Networking
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• v.31 no.4
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• pp.414-428
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• 2004

Many portable devices are coming to be commercially successful and provide useful services to mobile users. Mobile devices may request a variety of data types, including text and multimedia data, thanks to the rich content of the Internet. Different types of data and/or different classes of users may need to be treated with different qualities of service. The implementation of service differentiation in wireless networks is very difficult because of device mobility and wireless channel contention when the backoff algorithm is used to resolve contention. Modification of the t)mary exponential backoff algorithm is one possibility to allow the design of several classes of data traffic flows. We present a study of modifications to the backoff algorithm to support three classes of flows: sold, silver, and bronze. For example, the gold c]ass flows are the highest priority and should satisfy their required target bandwidth, whereas the silver class flows should receive reasonably high bandwidth compared to the bronze class flows. The mixture of the two different transport protocols, UDP and TCP, in ad hoc networks raises significant challenges when defining backoff algorithm modifications. Due to the different characteristics of UDP and TCP, different backoff algorithm modifications are applied to each class of packets from the two transport protocols. Nevertheless, we show by means of simulation that our approach of backoff algorithm modification clearly differentiates service between different flows of classes regardless of the type of transport protocol.

• Journal of the Korean Association of Geographic Information Studies
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• v.12 no.1
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• pp.1-11
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• 2009

Rapid visualization of flood area of downstream according to the dam effluent in flood season is very important in dam management works. Overlay zone of river bight should be removed to represent flood area efficiently based on flood stage which was modeled in river channels. This study applied drainage enforcement algorithm to visualize flood area considering river bight by coupling Coordinate Operation System for Flood control In Multi-reservoir (COSFIM) and Flood Wave routing model (FLDWAV). The drainage enforcement algorithm is a kind of interpolation which gives to advantage into hydrological process studies by removing spurious sinks of terrain in automatic drainage algorithm. This study presented mapping technique of flood area layer considering river bight in Namgang-Dam downstream, and developed system based on Arcobject component to execute this process automatically. Automatic extraction system of flood area layer could save time-consuming efficiently in flood inundation visualization work which was propelled based on large volume data. Also, flood area layer by coupling with IKONOS satellite image presented real information in flood disaster works.

• Archives of design research
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• v.11 no.2
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• pp.5-14
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• 1998

The hopes for making vivid images of mankind made 'film' that reflects easy communications. Film have made satisfactions to imagination of man by varied experimental expressions from the beginning. Many of directors and producers were eager to make film to be with relevant views. At last film has making to do with the digital tool, so called 'Computer Graphics' . Making images through computers have changed more better with the developing skills of softwares. NASA has developed Aero-Simulations first, it have called computer graphics for the first time in history. The computer graphics can make images with very varieties that had not exprerienced before and we won't expect the upcomming skills of it. Special Effects(SFX) through the films began the genre of Science Fiction in the era of ideology and space competetions and producer George Lucas made the firm named ILMOndustrial Light & Magic) to making picture of SFX. At last 'Abyss', 'Terminator II', 'Toy Story' and 'Forrest Gump' have made to us with many splendid arangements by the computers. Especially, we can concluded that the relevant expressions as in 'Forrest Gump' is the unexpected charming and human images with wonder. In Korean films are less varied, relevant and reasonable than that of American films, in this study I hope to develope more natural Korean computer graphic in near future.

• Journal of Wetlands Research
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• v.15 no.4
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• pp.585-593
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• 2013

This study aims to investigate inundation characteristics such as inundated area, inundation depth according to variation in return period of design rainfall and to draw a comparison between the inundation characteristics by adapting design storm using dual-drainage model. Lidar data is used to construct terrain data with $1m{\times}1m$ resolution in Cheongju. The designed storm by return periods(10year, 30year, 50year and 200year) are acquired from Intensity Duration Frequency curve, which are distributed in 5 minutes interval using Huff's method. As a results, the inundation volume is linearly increased, but inundated area is gradually increased in accordance with swell of return period for design storm. On the other hands, as a result of calculating discharge capacity for each points, deficit of discharge capacity is not observed using designed storm of 10 year return period at every points. If the return period is increased up more than 10 years, both the deficit of discharge capacity for each PT and entire study area are enlarged drastically.