• Journal of Broadcast Engineering
• /
• v.19 no.2
• /
• pp.174-183
• /
• 2014

This paper is to propose a scalable video coding scheme for adaptive digital hologram video service for various reconstruction environments. It uses both the light source information and digital hologram at both the sending side and the receiving side. It is a resolution-scalable coding method that scales the resolution, that is, the size of the reconstructed image. The method compresses the residual data for both the digital hologram and the light source information. For the digital hologram, a lossy compression method is used, while for the light source information, a lossless compression method is used. The experimental results showed that the proposed method is superior to the existing method in the image quality at the same compression ratio. Especially it showed better performance than the existing method as the compression ratio becomes higher.

• Korean Journal of Optics and Photonics
• /
• v.23 no.1
• /
• pp.23-31
• /
• 2012

In this paper, we developed a frequency-domain diffuse optical imaging (DOI) system for imaging non-invasively using near-infrared (NIR) light sources and detectors. 70-MHz modulation and a homodyne scheme were adopted. By calibration of the coupling coefficients, concurrent detection measurements by 4 detector sets were optimized. We presented experimental reconstruction images of absorption and scattering coefficients in a liquid phantom, located an anomaly in the phantom and determined its optical properties. The images by the multi-channel concurrent detection were improved over the results by single-channel sequential detection. Tomographic slices of absorption and scattering coefficients in the phantom with an anomaly were also presented.

• The Journal of the Korea Contents Association
• /
• v.16 no.8
• /
• pp.706-716
• /
• 2016

Because of efficient space utilization and fast key search times, B-trees have been widely accepted for the use of indexes in HDD-based DBMSs. However, when the B-ree is stored in flash memory, its costly operations of node updates may impair the performance of a DBMS. This is because the random updates in B-tree's leaf nodes could tremendously enlarge I/O costs for the garbage collecting actions of flash storage. To solve the problem, we make all the parents of leaf nodes the virtual nodes, which are not stored physically. Rather than, those nodes are dynamically generated and buffered by referring to their child nodes, at their access times during key searching. By performing node updates and tree reconstruction within a single flash block, our proposed B-tree can reduce the I/O costs for garbage collection and update operations in flash. Moreover, our scheme provides the better performance of key searches, compared with earlier flash-based B-trees. Through a mathematical performance model, we verify the performance advantages of the proposed flash B-tree.

• Journal of KIISE:Information Networking
• /
• v.30 no.6
• /
• pp.685-694
• /
• 2003

Recently as the mobile computing is burgeoning, multimedia services have become very popular. Multimedia services require large data volume and have to send the same data to several users. In order to provide efficient multimedia services that have those characteristic to mobile users, efficient multicast technique to support host mobility is required. Previous research that support multicast services in mobile computing based on Mobile IP have the non-optimization problem of data delivery path, overhead by frequent reconstruction of the multicast tree, and service disruption problem. In this paper, we propose the mobility pattern based multicast technique using variable service range according to the mobility of mobile hosts and resource reservation to solve this problems. The experimental results show that our proposed mechanism has improved performance than previous research.

• The KIPS Transactions:PartD
• /
• v.11D no.5
• /
• pp.1149-1158
• /
• 2004

Today the fastest growing communities of web users are mobile visitors who browse web page with wireless PDAs and cellular phones. However, most web pages are optimiaed exclusively for desktop clients on the broadband network and are inconvenient to users with small screen mobile devices. They display only a few lines of text and cannot run client-side programs or scripts due to lack of system resource. Even worse, their connections are usually slow to support most of the data-intensive applications. In this paper, we propose a pageslet scheme that makes it feasible to browse ordinary web pages on small screen mobile devices. It extracts broadcasting sections of user preference from broadcasting web pages and automatically reorganizes the extracted sections for convenient browsing on mobile devices.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.26 no.4
• /
• pp.223-231
• /
• 2013

This paper presents a time-domain Gauss-Newton full-waveform inversion method for the material profile reconstruction in heterogeneous semi-infinite solid media. To implement the inverse problem in a finite computational domain, perfectly-matchedlayers( PMLs) are introduced as wave-absorbing boundaries within which the domain's wave velocity profile is to be reconstructed. The inverse problem is formulated in a partial-differential-equations(PDE)-constrained optimization framework, where a least-squares misfit between measured and calculated surface responses is minimized under the constraint of PML-endowed wave equations. A Gauss-Newton-Krylov optimization algorithm is utilized to iteratively update the unknown wave velocity profile with the aid of a specialized regularization scheme. Through a series of one-dimensional examples, the solution of the Gauss-Newton inversion was close enough to the target profile, and showed superior convergence behavior with reduced wall-clock time of implementation compared to a conventional inversion using Fletcher-Reeves optimization algorithm.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.40 no.4
• /
• pp.619-627
• /
• 2015

This paper presents a speech enhancement method using non-negative matrix factorization (NMF). In the training phase, each basis matrix of source signal is obtained from a proper database, and these basis matrices are utilized for the source separation. In this case, the performance of speech enhancement relies heavily on the basis matrix. The proposed method for which speech basis matrix is made a high reconstruction error for noise signal shows a better performance than the standard NMF which basis matrix is trained independently. For comparison, we propose another method, and evaluate one of previous method. In the experiment result, the performance is evaluated by perceptual evaluation speech quality and signal to distortion ratio, and the proposed method outperformed the other methods.

• Journal of Information Processing Systems
• /
• v.15 no.6
• /
• pp.1472-1488
• /
• 2019

Critical elements in the China's Lunar Exploration reside in that the lunar rover travels over the surrounding undetermined environment and it conducts scientific exploration under the ground control via teleoperation system. Such an interplanetary transportation mission teleoperation system belongs to the ground application system in deep space mission, which performs terrain reconstruction, visual positioning, path planning, and rover motion control by receiving telemetry data. It plays a vital role in the whole lunar exploration operation and its so-called trustworthy evidence must be assessed before and during its implementation. Taking ISO standards and China's national military standards as trustworthy evidence source, the net assessment model and net assessment method of teleoperation system are established in this paper. The multi-dimensional net assessment model covering the life cycle of software is defined by extracting the trustworthy evidences from trustworthy evidence source. The qualitative decisions are converted to quantitative weights through the net assessment method (NAM) combined with fuzzy analytic hierarchy process (FAHP) and entropy weight method (EWM) to determine the weight of the evidence elements in the net assessment model. The paper employs the teleoperation system for interplanetary transportation as a case study. The experimental result drawn shows the validity and rationality of net assessment model and method. In the final part of this paper, the untrustworthy elements of the teleoperation system are discovered and an improvement scheme is established upon the "net result". The work completed in this paper has been applied in the development of the teleoperation system of China's Chang'e-3 (CE-3) "Jade Rabbit-1" and Chang'e-4 (CE-4) "Jade Rabbit-2" rover successfully. Besides, it will be implemented in China's Chang'e-5 (CE-5) mission in 2019. What's more, it will be promoted in the Mars exploration mission in 2020. Therefore it is valuable to the development process improvement of aerospace information system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2001.10a
• /
• pp.487-490
• /
• 2001

With the establishment of the optimized copyright, digital image watermarking technique is demended to identify the owner of a certain image and to avoid the unauthorized distribution of digital image copies. Also, a robust watermarking approach should survive several possible attacks, such as image processing and lossy image compession. The proposed scheme distributes the 256 gray-level signature information in discrete wavelet transform domain of the host image where is very little visible distortion. While much of the privious work used signature data that is a small fraction of th e host images the proposed approach can easily handle gray-scale Images. As the result, stable reconstruction can be obtained even when the images are transformed, JPEG lossy compression or otherwise modified by low-pass filtering operations.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.32 no.4
• /
• pp.322-329
• /
• 2016

Reconstruction of the maxillectomy with an obturator is to restore masticatory, swallowing, phonetic and esthetic problems. Stress created by lateral forces is minimized by the proper selection of an occlusal scheme, elimination of premature occlusal contacts, and wide distribution of supporting area. It should be considered that properly designed retainers reduce the stresses transmitted to the abutment while the obturator is in function. The following clinical report presents palatal obturator treatment with implant assisted removable partial denture (IARPD) design that restores normal function and esthetics in patients who experienced maxillectomy and dental implant failure.