• Journal of the Institute of Electronics Engineers of Korea CI
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• v.49 no.1
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• pp.23-28
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• 2012

The performance improvement of the secondary storage is very slow compared to the main memory and processor. The data is loaded from secondary storage to memory for the execution of an application. At this time, there is a bottleneck. In this paper, we propose an Executable Compression Method to speed up the initial loading time of application. and we examined the performance. So we implemented the two applications. The one is a compressor for Execution Binary File. and The other is a decoder of Executable Compressed application file on the Embedded System. Using the test binary files, we performed the speed test in the six files. At the result, one result showed that the performance was decreased. but others had a increased performance. the average increasing rate was almost 29% at the initial loading time. The level of compression had different characteristics of the file. And the performance level was dependent on the file compressed size and uncompress time. so the optimized compression algorithm will be needed to apply the execution binary file.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.1
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• pp.84-89
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• 2019

JPEG is a most widely used standard image compression technology. This research introduces the JPEG image compression algorithm and describes each step in the compression and decompression. Image compression is the application of data compression on digital images. The DCT (discrete cosine transform) is a technique for converting a time domain to a frequency domain. First, the image is divided into 8 by 8 pixel blocks. Second, working from top to bottom left to right, the DCT is applied to each block. Third, each block is compressed through quantization. Fourth, the matrix of compressed blocks that make up the image is stored in a greatly reduced amount of space. Finally if desired, the image is reconstructed through decompression, a process using IDCT (inverse discrete cosine transform). The purpose of this research is to review all the processes of image compression / decompression using the discrete cosine transform method.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.34 no.3
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• pp.379-392
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• 2024

With the rapid increase in data, saving storage space and improving the efficiency of data transmission have become critical issues, making the research on the efficiency of data compression technologies increasingly important. Lossless algorithms can precisely restore original data but have limited compression ratios, whereas lossy algorithms provide higher compression rates at the expense of some data loss. There has been active research in data compression using deep learning-based algorithms, especially the autoencoder model. This study proposes a new side-channel analysis data compressor utilizing autoencoders. This compressor achieves higher compression rates than Deflate while maintaining the characteristics of side-channel data. The encoder, using locally connected layers, effectively preserves the temporal characteristics of side-channel data, and the decoder maintains fast decompression times with a multi-layer perceptron. Through correlation power analysis, the proposed compressor has been proven to compress data without losing the characteristics of side-channel data.

• Journal of the Korean GEO-environmental Society
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• v.17 no.4
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• pp.33-37
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• 2016

The hydration process of Controlled Low Strength Material (CLSM) used for backfill is the primary factor to determine the construction period. The objective of this study is to monitor the hydration process of CLSM using the Time Domain Reflectometry (TDR) and to establish the relationship between dielectric constant and compressive strength. The CLSM specimen is composed of cement, flyash, silt, sand, accelerator, and water. The material characteristics of the CLSM including flow, unit weight, compressive strength are investigated. To measure the dielectric constant of the CLSM during the curing time, TDR probe incorporated with a mold and a reflectometer are used. Experimental results show that the dielectric constant remains constant at early stage, and then decreases as the curing time increases. In addition, the dielectric constant is related to the compressive strength in inverse power function. This paper suggests that the TDR technique may be used as a non-destructive testing method in order to estimate the compressive strength of the CLSM mixture under construction.

• KIPS Transactions on Computer and Communication Systems
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• v.9 no.3
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• pp.45-58
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• 2020

In the current trend of increasing network traffic due to the popularization of cloud service and mobile devices, WAN bandwidth is very low compared to LAN bandwidth. In a WAN environment, a WAN optimizer is needed to overcome performance problems caused by transmission protocol, packet loss, and network bandwidth limitations. In this paper, we analyze the data deduplication algorithm of WANProxy, an open source WAN optimizer, and evaluate its performance in terms of network latency and WAN bandwidth. Also, we evaluate the performance of the two-stage compression method of WANProxy and Zstandard. We propose a new method to improve the performance of WANProxy by revising its data deduplication algorithm and evaluate its performance improvement. We perform experiments using 12 data files of Silesia with a data segment size of 2048 bytes. Experimental results show that the average compression rate by WANProxy is 150.6, and the average network latency reduction rates by WANProxy are 95.2% for a 10 Mbps WAN environment and 60.7% for a 100 Mbps WAN environment, respectively. Compared with WANProxy, the two-stage compression of WANProxy and Zstandard increases the average compression rate by 33%. However, it increases the average network latency by 2.1% for a 10 Mbps WAN environment and 5.27% for a 100 Mbps WAN environment, respectively. Compared with WANProxy, our proposed method increases the average compression rate by 34.8% and reduces the average network latency by 13.8% for a 10 Mbps WAN and 12.9% for a 100 Mbps WAN, respectively. Performance analysis results of WANProxy show that its performance improvement in terms of network latency and WAN bandwidth is excellent in a 10Mbps or less WAN environment while superior in a 100 Mbps WAN environment.

• Restorative Dentistry and Endodontics
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• v.35 no.5
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• pp.344-352
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• 2010

Objectives: The purpose of this study was to determine the setting time, compressive strength, solubility, and pH of mineral trioxide aggregate (MTA) mixed with glass ionomer cement (GIC) and to compare these properties with those of MTA, GIC, IRM, and SuperEBA. Materials and Methods: Setting time, compressive strength, and solubility were determined according to the ISO 9917 or 6876 method. The pH of the test materials was determined using a pH meter with specified electrode for solid specimen. Results: The setting time of MTA mixed with GIC was significantly shorter than that of MTA. Compressive strength of MTA mixed with GIC was significantly lower than that of other materials at all time points for 7 days. Solubility of 1 : 1 and 2 : 1 specimen from MTA mixed with GIC was significantly higher than that of other materials. Solubility of 1 : 2 specimen was similar to that of MTA. The pH of MTA mixed with GIC was 2-4 immediately after mixing and increased to 5-7 after 1 day. Conclusions: The setting time of MTA mixed with GIC was improved compared with MTA. However, other properties such as compressive strength and pH proved to be inferior to those of MTA. To be clinically feasible, further investigation is necessary to find the proper mixing ratio in order to improve the drawbacks of MTA without impairing the pre-existing advantages and to assess the biocompatibility.

• Proceedings of the Korean Information Science Society Conference
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• 1999.10b
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• pp.245-247
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• 1999

본 논문은 MPEG-2 TM 5 비디오 부호기의 움직임 예측(motion estimation) 처리과정을 소개한다. 비디오에는 공간의 중복성보다 시간의 중복성이 훨씬 많다. 따라서 시간의 중복성을 찾아내는 것이 압축의 효율을 높이는 중요한 척도가 된다. MPEG-2 부호기는 움직임 예측 알고리즘을 사용하여 시간의 중복성을 줄여 압축 효율을 높인다. 움직임 예측은 참조 블록의 위치로부터 원래 블록의 위치를 추정하여 최적의 움직임 벡터를 찾는 과정이다. PMEG-2에서의 움직임 예측은 full search 알고리즘을 사용하여 마지막으로 hlaf pel로 산출한다. 본 논문에서는 MPEG-2 움직임 예측 과정을 frame estimation, field estimation, picture 타입에 따른 estimation, 움직임 예측을 위한 블록 매칭 알고리즘, full search 방법 및 움직임 벡터에 대하여 소개한다.

• Proceedings of the Korean Information Science Society Conference
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• 2003.04d
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• pp.614-616
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• 2003

기존의 비디오 코딩에서는 연속된 프레임의 시간적인 상관성을 제거하기 위한 방법으로 이전 프레임의 정보를 이용하여 현재 프레임을 예측하는 움직임 예측기법을 많이 사용하고 있다. 정지 화상에 비해서 대용량의 특성을 지니는 비디오 데이터는 이런 움직임 예측을 통해서 대부분의 압축이 일어나게 된다. 하지만 움직임 예측기법은 않은 계산과정을 요구하므로, 전체적인 부호기 복잡도를 높이는 단점을 지닌다. 반면 30-WT는 움직임 예측을 하지 않으므로, 부호기의 복잡도를 줄일 수 있다. 하지만. 기존의 30-WT기법들은 부호화를 위한 메모리 요구사항과 복호를 위한 수신측의 지연시간이 가장 큰 단점으로 지적되었다. 따라서, 본 논문에서는 메모리 요구사항과 수신측의 지연시간을 최소로 할 수 있는 효율적이고, 확장가능한 3D-WT 기법을 소개한다.

• Proceedings of the Korean Information Science Society Conference
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• 2004.04b
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• pp.766-768
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• 2004

동영상에서 객체의 추출은 객체 단위로 압축하는 MPEG-4와 객체의 특성을 기술하고 유사한 영상을 검색하는 기능을 가진 MPEG-7에 기반 기술로, 동영상의 효과적인 압축 및 색인, 검색에 유용하게 사용되는 방법이다. 본 논문에서는 시간적 정보와 공간적 정보를 이용한 영상 분할 방법을 제시한다. 동영상은 배경 화면과 전방 객체로 이루어져 있는데, 여기서 프레임간 모션벡터로 글로벌영상(배경영상)의 움직임을 분리할 수 있다. 이 Motion-based Segmentation을 통해 배경과 전방객체를 분리하여 rough한 전방객체를 추출하게 된다. 그리고 시간적 분할을 통해 얻은 rough한 전방객체에 모폴로지 변환과 Watershed 알고리즘을 적용하여 배경과 전방객체의 모호한 부분을 제거함으로써 효과적으로 전방객체를 추출한다.

• Annual Conference of KIPS
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• 2008.05a
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• pp.115-118
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• 2008

H.264/AVC는 동영상 데이터를 효율적으로 전송하기 위한 압축 기술로써 7가지 가변 블록에 대한 움직임 예측(Motion Estimation) 및 움직임 보상(Motion Compensation), DCT(Discrete Cosine Transform), 엔트로피 부호화(Entropy Coding), 디블록킹 필터 등 여러 가지 방법이 있다. 이러한 방법들로 인해 압축 효율은 높아졌으나 많은 계산량으로 인해 부호화 시간이 증가하게 되었다. 따라서 화질 손실을 최소한으로 줄이면서 소모되는 시간을 단축시키는 H.264 부호화 방법들이 개발되어야 한다. 그래서 본 논문에서는 H.264 부호화 과정 중 시간이 많이 소모되는 움직임 예측에서 움직임 벡터를 찾기 위한 방법을 제안한다.