• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권3호
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• pp.471-489
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• 2013

Data compression at the transport layer could both reduce transmitted bytes over network links and increase the transmitted application data (TCP PDU) in one RTT at the same network conditions. Therefore, it is able to improve transmission efficiency on Internet, especially on the networks with limited bandwidth or long delay links. In this paper, we propose an on-the-fly TCP data compression scheme, i.e., the TCPComp, to enhance TCP performance. This scheme is primarily composed of the compression decision mechanism and the compression ratio estimation algorithm. When the application data arrives at the transport layer, the compression decision mechanism is applied to determine which data block could be compressed. The compression ratio estimation algorithm is employed to predict compression ratios of upcoming application data for determining the proper size of the next data block so as to maximize compression efficiency. Furthermore, the assessment criteria for TCP data compression scheme are systematically developed. Experimental results show that the scheme can effectively reduce transmitted TCP segments and bytes, leading to greater transmission efficiency compared with the standard TCP and other TCP compression schemes.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권7호
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• pp.3245-3271
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• 2016

To obtain well-dehazed images at the receiver while sustaining low bit rates in the transmission pipeline, this paper investigates the effects of image dehazing methods using dehazing contrast-enhancement filters on image compression for surveillance systems. At first, this paper proposes a novel image dehazing method by using a new method of calculating the transmission function—namely, the direct denoising method. Next, we deduce the dehazing effects of the direct denoising method and image dehazing method based on dark channel prior (DCP) on image compression in terms of ringing artifacts and blocking artifacts. It can be concluded that the direct denoising method performs better than the DCP method for decompressed (reconstructed) images. We also improve the direct denoising method to obtain more desirable dehazed images with higher contrast, using the saliency map as the guidance image to modify the transmission function. Finally, we adjust the parameters of dehazing contrast-enhancement filters to obtain a corresponding composite peak signal-to-noise ratio (CPSNR) and blind image quality assessment (BIQA) of the decompressed images. Experimental results show that different filters have different effects on image compression. Moreover, our proposed dehazing method can strike a balance between image dehazing and image compression.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.88-88
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• 2002

Satellite Image archiving system requires large storage and long transmission time. A simple and cheap way of overcoming these limitations is to increase the compression ratio. However this requires a feasibility study for accurate applications. Here, a new still image compression standard is being developed, the JPEG2000. It provides lossless and lossy compression, progressive transmission by pixel accuracy and by resolution, region-of-interest coding, user-defined tiling size, random codestream access and processing etc. In this study, we will briefly introduce the JPEG2000 compression standard which provides a new compression technique based on the wavelet technology and offers better compression ratios, and evaluate the compression ratios of JPEG2000 for satellite image by performing various image quality tests. Also, we will compare brief test result using the commercial remote sensing software.

• 한국정보통신학회논문지
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• 제10권7호
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• pp.1253-1258
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• 2006

모바일 벡터 지도 서비스 환경에는 공간 데이터의 특성상 큰 데이터 용량으로 인한 단말기 리소스 부족과 전송시간 지연과 같은 애로사항이 존재 한다. 정상적인 모바일 벡터 지도 서비스가 이루어지기 위해서는 이러한 문제점들을 극복하기 위한 대책들이 필요하다 그중에서 공간데이터 압축기법은 대역폭과 클라이언트에서의 대기 시간 축소에 도움을 줄 수 있다. 하지만 압축과 복원에 소요되는 오버헤드가 전체 효율에 미치는 영향도 함께 고찰할 필요가있다. 본 논문은 공간 데이터를 압축하기 위한 2가지 기법을 제시한다. 하나는 공간 객체별로 기준 좌표 및 상대 좌표를 전송하는상대좌표 변환 압축기법이고 또 하나는 클라이언트 좌표로 서버에서 미리 좌표 변환하는 클라이언트 좌표 변환 압축 기법이다. 그리고 구현 실험으로 그 효과와 효율을 평가한다.

• 대한의용생체공학회:의공학회지
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• 제16권3호
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• pp.271-278
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• 1995

An ECG data compression algorithM using max-min slope update is proposed and a real time 3 channel ECG transmission system is implemented using the proposed algorithm. In order to effectively compress ECG data, we compare a threshold value with the max-min slope difference (MMSD) which is updated at each sample values. If this MMSD value is smaller than the threshold value, then the data is compressed. Conversely, when the MMSD value is larger than threshold value, the data is transmitted after storing the value and the length between the data which is beyond previous threshold level. As a result, it can accurately compress both the region of QRS, P, and T wave that has fast-changing and the region of the base line that slope is changing slow. Therefore, it Is possible to enhance the compression rate and the percent roms difference. In addition, because of the simplicity, this algorithm is more suitable for real-time implementation.

• 정보처리학회논문지:컴퓨터 및 통신 시스템
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• 제3권10호
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• pp.371-376
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• 2014

u-Healthcare에서는 다양한 생체 정보를 지속적으로 수집하는 것이 필요하다. 이를 위해 센서와 서버 간의 효율적인 네트워크 환경으로써 IoT가 고려된다. 본 논문에서는 이러한 IoT 환경에 적합한 전송 방식 및 압축 알고리즘을 제안하였다. 결과는 기존의 압축 알고리즘 및 선행연구들과 비교하였다. 결과에서 본 논문에서 제안하는 알고리즘의 압축효율이 11.7이 됨을 알 수 있었다.

• Imaging Science in Dentistry
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• 제30권4호
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• pp.265-274
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• 2000

Purpose: The aims of the present study are to determine the optimum compression rate in terms of file size reduction and diagnostic quality of the images after compression and evaluate the transmission speed of original or each compressed image. Materials and Methods: The material consisted of 24 extracted human premolars and molars. The occlusal surfaces and proximal surfaces of the teeth had a clinical disease spectrum that ranged from sound to varying degrees of fissure discoloration and cavitation. The images from Digora system were exported in TIFF and the images from conventional intraoral film were scanned and digitalized in TIFF by Nikon SF-200 scanner (Nikon, Japan). And six compression factors were chosen and applied on the basis of the results from a pilot study. The total number of images to be assessed were 336. Three radiologists assessed the occlusal and proximal surfaces of the teeth with 5-rank scale. Finally diagnosed as either sound or carious lesion by one expert oral pathologist. And sensitivity, specificity and k value for diagnostic agreement was calculated. Also the area (Az) values under the ROC curve were calculated and paired t-test and oneway ANOVA test was performed. Thereafter, transmission time of the image files of the each compression level was compared with that of the original image files. Results: No significant difference was found between original and the corresponding images up to 7% (1 : 14) compression ratio for both the occlusal and proximal caries (p<0.05). JPEG3 (1 : 14) image files are transmitted fast more than 10 times, maintained diagnostic information in image, compared with original image files. Conclusion: 1 : 14 compressed image file may be used instead of the original image and reduce storage needs and transmission time.

• Structural Engineering and Mechanics
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• 제81권4호
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• pp.481-492
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• 2022

Cycloidal ball planetary transmission (CBPT) has many applications as precision reducer, such as precision machinery and automation drive systems etc. The traditional analytical model of CBPT cannot accurately describe the change of the normal force of meshing points, and thus cannot describe the precise transmission process of meshing pairs. In the paper, a method for deriving the normal force equation is put forward by using the non-linear relationship between force and deformation in elastic mechanics. The two-point contact analytical models of all the meshing pairs are established to obtain the micro-displacement analytical model of CBPT under axial pre-tightening. Then, the non-real-time two-point contact analytical models of all the meshing pairs are further constructed to obtain the normal force expression to determine the critical compression coefficients. Experimental investigations are performed to verify the analytical model using the critical compression coefficients.

• 한국CDE학회논문집
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• 제7권2호
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• pp.81-88
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• 2002

Transmission of 3D shape model through Internet has become one of the hottest issues in these days. Presented in this paper is a new approach for the rapid transmission of the geometry data of the shape model. By analyzing the important three factors, the shape fidelity, the file size, and the decompression time, for the compression, we point out the potential problems of previous approaches of using the deltas between consecutive vertices and propose an alternative of directly using the position values of vertices of the model. It turns out that the proposed approach has smaller file size, has lesser distortion in the model, and the decompression is faster.

• IEIE Transactions on Smart Processing and Computing
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• 제1권3호
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• pp.182-191
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• 2012

This paper proposes a high performance QoS (Quality of Service) traffic transmission scheme to provide real-time multimedia services in wireless networks. This scheme is based on both a traffic estimation of the mean rate and a header compression method by dividing this network model into two parts, core RTP/UDP/IP network and wireless access parts, using the IEEE 802.11 WLAN. The improvement achieved by the scheme means that it can be designed to include a means of provisioning the high performance QoS strategy according to the requirements of each particular traffic flow by adapting the header compression for real-time multimedia data. A performance evaluation was carried out to show the effectiveness of the proposed traffic transmission scheme.