• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.12 no.1
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• pp.89-94
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• 1994

A number of the latest research projects focus on the development of real-time mapping system. Typically, these devices are used to capture land-related information in digital form from airplanes or cars. The purpose of this paper is to automatically extract the road information from the digital images obtained using the so-called "GPS-Van" which has been developed by Center for Mapping at The Ohio State University, and to propose the method for the effective storage and management of the digital data. The edges of a road can be extracted from the digital image and determined real-time 3-dimensional position by digital photogrammetry. Also, the three storage level which consists of raster data level, object-oriented data level, and vector data level in the data storage and Quadtree data structure for the effective compression and search in the data management was proposed in this paper.his paper.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.7
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• pp.1214-1221
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• 2006

Header compression scheme is suggested as a solution to reduce the inefficient overhead of general packet stream data. Especially, it is shown that there are more overhead rate for real-time media stream links such as voice because of its short payload size, and it is possible to get higher bandwidth efficiency using the header compression scheme. There are two kinds of error recovery in header compression such as Periodic Header Refresh(PHR) and Header Request(HR) schemes. In this paper, we analyze the performance of these two compression recovery schemes, and some results such as the overhead rate, bandwidth gain and bandwidth efficiency(BE) are presented.

• ETRI Journal
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• v.46 no.4
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• pp.683-696
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• 2024

The point cloud provides viewers with intuitive geometric understanding but requires a huge amount of data. Moving Picture Experts Group (MPEG) has developed video-based point-cloud compression in the range of 300-700. As the compression rate increases, the complexity increases to the extent that it takes 101.36 s to compress one frame in an experimental environment using a personal computer. To realize real-time point-cloud compression processing, the direct patch projection (DPP) method proposed herein simplifies the complex patch segmentation process by classifying and projecting points according to their geometric positions. The DPP method decreases the complexity of the patch segmentation from 25.75 s to 0.10 s per frame, and the entire process becomes 8.76 times faster than the conventional one. Consequently, this proposed DPP method yields similar peak signal-to-noise ratio (PSNR) outcomes to those of the conventional method at reduced times (4.7-5.5 times) at the cost of bitrate overhead. The objective and subjective results show that the proposed DPP method can be considered when low-complexity requirements are required in lightweight device environments.

• Journal of the Korea Computer Industry Society
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• v.3 no.3
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• pp.283-294
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• 2002

Now is the time for web-based video e-mail system because of world wide use of internet. But video data is so large, then data compression is much needed for transmission by web. In this paper, my colleagues and I implement full motion video e-mail system using MPEG-4, the international standards for audio-visual data. This video e-mail system is made of web-based active-X control, so easily accessible by web, and applies real-time audio-video compression. It's possible for everyone to send video e-mail for free to everywhere in the world if this system is used. The main application areas of this system are multimedia mailing service, web-based video advertisement, remote education, remote medical service and shopping mall construction, etc.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.2
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• pp.7-13
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• 2002

When a USB digital camera is used for PC video-conference applications, motion picture data need to be transferred to the PC through the USB port. Due to the mismatch between the data rates of the USB and the motion picture, data compression should be performed before the transmission from the USB. While many motion picture compression algorithms require large intermediate memory space, the JPEG algorithm does not need to store an entire frame for the compression. Instead, a relatively small buffer is required at the input of the JPEG compression engine to resolve the inconsistency between the orders of the inputted data and the consumed data. Data reordering can be easily implemented using a double buffering scheme, which still requires a considerable size of memory. In this paper, a novel memory management scheme is proposed to avoid the double buffering. The proposed memory architecture requires a small amount of memory and a simple address generation scheme, resulting in overall cost reduction.

• The KIPS Transactions:PartB
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• v.9B no.6
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• pp.745-752
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• 2002

The purpose of the paper is to enable a format transcoding between a heterogeneous compression format in a real time, and to enhance the compression ratio using characteristics of the compressed frame. In this paper, for the heterogeneous format transcoding, we tried to transcode from MPEG2 having a lower compression ratio to H.263 having a higher compression ratio. After analyzing MPEG 2 bit stream and H.263 bit stream of the same original video, we found that the number of intra coded macro blocks in MPEG 2 data is much higher than the number of the intra coded macro blocks in H.263 data. In the process of P frame generation, a intra coded macro block is generated when a motion estimation value representing the similarity between the previous frame and current frame does not meet a threshold. Especially the intra coded macro block has a great impact on the compression ratio. Hence the paper, we tried to minimize the number of intra coded macro blocks in H.263 data stream which is transcoded from MPEG 2 in a compressed domain. For the purpose, we propose a guided search method for transcoding the INTRA coded block into INTER coded block using the information about motion vectors surrounding the intra macro block in order to minimize the complexity of the motion estimation process. The experimental results show that the transcoding of MPEG 2 into H.263 can be done in a real time successfully.

• ETRI Journal
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• v.29 no.5
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• pp.655-666
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• 2007

There are nodes and edges in a topological map. Node data has been used as a main source of information for the localization of mobile robots. In contrast, edge data is regarded as a minor source of information, and it has been used in an intuitive and heuristic way. However, edge data also can be used as a good source of information and provide a way to use edge data efficiently. For that purpose, we define a data format which describes the shape of an edge. This format is called local generalized Voronoi graph's angle (LGA). However, the LGA is constituted of too many samples; therefore, real time localization cannot be performed. To reduce the number of samples, we propose a compression method which utilizes wavelet transformation. This method abstracts the LGA by key factors using far fewer samples than the LGA. Experiments show that the LGA accurately describes the shape of the edges and that the key factors preserve most information of the LGA while reducing the number of samples.

• Journal of KIISE:Computer Systems and Theory
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• v.30 no.10
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• pp.586-594
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• 2003

X-Match algorithm is a lossless compression algorithm suitable for hardware implementation owing to its simplicity. It can compress 32 bits per clock cycle and is suitable for real time compression. However, as the bus width increases 64-bit, the compression unit also need to increase. This paper proposes the cooperative parallel X-Match (X-MatchCP) algorithm, which improves the compression speed by performing the two X-Match algorithms in parallel. It searches the all dictionary for two words, combines the compression codes of two words generated by parallel X-Match compression and outputs the combined code while the previous parallel X-Match algorithm searches an individual dictionary. The compression ratio in X-MatchCP is almost the same as in X-Match. X-MatchCP algorithm is described and simulated by Verilog hardware description language.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.6
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• pp.1076-1085
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• 2004

Recently, the demands for real-time service and multimedia data are rapidly increasing. There are significant redundancies between header fields both within the same packet header and in consecutive packets belonging to the same packet stream. And there are many overheads in using the current UDP/IP protocol. Header compression is considered to enhance the transmission efficiency for the payload of small size. By sending the static field information only once initially and by utilizing dependencies and predictability for other fields, the header size can be significantly reduced for most packets. This work describes an implementation for header compression of the headers of IP/UDP protocols to reduce the overhead on Ethernet network. Typical UDP/IP Header packets can be compressed down to 7 bytes and the header compression system is designed and implemented in Linux environment. Using the Header compression system designed between a server and clients provides have the advantage of effective data throughput in network. Since the minimum packet size in Ethernet is 64 bytes, the amount of reduction by header compression in practical chatting environment was 6.6 bytes.

• The Korean Journal of Emergency Medical Services
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• v.12 no.3
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• pp.27-41
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• 2008

Purpose : The purpose of this study was to supply basic data for the impact on the accuracy of basic CPR according to position and foot-board height of basic CPR provider. Methods : Study design was within - group design. Subjects were 25 EMT-P Students in K city. Interventions was basic CPR performed on a resuscitation manikin placed on a hospital bed, kneeling on the bed adjacent to the manikin. Data was analyzed using descriptive statistics and Friedman test. Results : In case of the basic CPR performed on a resuscitation manikin placed on a hospital bed, ventilation accuracy was the highest in less than 160 cm height, foot-board height : $34.2{\pm}1.48cm$, 91.4% and in 161-165 cm height, foot-board height : $26.0{\pm}2.14cm$, 88.4% and in 171-175 cm height, foot-board height : $23.0{\pm}1.41cm$, 91.3% and in the above 176 cm, kneeling on the bed, 95%. Chest compression accuracy was the highest in less than 160 cm height, foot-board height : $30.2{\pm}1.48cm$, 95.6% and in 161-165 cm height, kneeling on the bed, 97.6% and in 171-175 cm height, kneeling on the bed, 98.5% and in the above 176 cm, kneeling on the bed, 98.7% and foot-board height : $20.5{\pm}1.91cm$, 98.7%. Chest compression error was due to too weak : 2.0-35.4 times. There were ststistically significant differences in 191-195 cm group according to chest compression mean depths($x^2=10.824$, p = .013) and chest compression error (p = .040). Conclusion : In contrast to current guidelines, the position and foot-board height of basic CPR provider are very important to the accuracy of the basic CPR. Furthermore, we recommend that a using real time audiovisual feedaback system significantly improve the quality of chest compression and ventilation during resuscitation.