• Proceedings of the Korea Inteligent Information System Society Conference
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• 2007.05a
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• pp.357-364
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• 2007

장치장 재정돈이란 장치장 크레인의 유휴시간을 활용하여 최대의 효율로 적하작업을 할 수 있도록 장치장의 컨테이너들을 미리 재배치하는 작업을 말한다. 본 논문에서는 수직 배치 자동화 컨테이너 터미널의 장치장을 대상으로 블록 내 재정돈 작업 계획을 수립하는 알고리즘을 제안한다. 제안된 알고리즘은 장치장 재정돈 작업 계획을 목표 장치형태 결정 및 크레인 작업 계획의 2단계로 나누어 수립한다. 시뮬레이션 시스템을 이용하여 재정돈을 수행하기 전과 후의 장치장에 대해 적하 작업 효율을 비교한 결과 재정돈 후 안벽 크레인의 대기 시간이 감소하고, 장치장의 재취급 작업 수가 줄어드는 등 적하 작업 효율이 향상되는 것을 확인하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.10a
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• pp.191-194
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• 2000

본 논문에서는 기존의 정렬 알고리즘의 성능을 향상시키기 위하여 정보블록 전처리 알고리즘(IBPA)이라는 전처리알고리즘을 제안한다. IBPA는 정렬될 리스트(list)에 있는 데이터에 관한 정보를 생성하고, 생성된 정보를 이용하여 각 데이터를 재배치하며, 실제적인 정렬은 기존의 정렬 알고리즘을 그대로 이용하여 이루어진다. IBPA의 성능을 측정해본 결과, 2백만개의 랜덤데이터를 정렬한 경우, O($N^2$)의 평균시간복잡도를 갖는 정렬알고리즘의 0.003%, O(NlogN) 의 평균시간복잡도를 갖는 정렬알고리즘의 52%, 그리고 O(N)의 평균시간복잡도를 갖는 정렬알고리즘의 89%정도의 비교회수만으로도 정렬할 수 있음을 보여주었다.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.1
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• pp.64-70
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• 2008

The H.264 standard is widely used due to the high compression rate and quality. The deblocking filter of the H.264 standard improves the quality of images by eliminating blocking artifacts of pictures, and it requires a lot of computation. We propose a new hardware architecture for the deblocking filter with pipelined architecture, 1-D filters which support both horizontal and vertical filtering and efficient memory management. Four memory blocks are configured for the efficient storage and access of the current macroblock and adjacent referenced sub-macroblocks, and the pixel data from the motion compensation unit can be transferred without waiting during the computation cycles of the deblocking filter. The number of computation cycles and the hardware area are reduced using the proposed architecture, and the performance of the H.264 decoder is improved. We design the deblocking filter using Verilog-HDL and implement using an FPGA. The designed deblocking filter can be used for decoding HD quality images at 77 MHz.

• Journal of KIISE
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• v.43 no.6
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• pp.627-635
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• 2016

When many processes issue write operations alternately on Log-structured File System (LFS), the created files can be fragmented on the file system layer although LFS sequentially allocates new blocks of each process. Unfortunately, this file fragmentation degrades read performance because it increases the number of block I/Os. Additionally, read-ahead operations which increase the number of data to request at a time exacerbates the performance degradation. In this paper, we suggest a new cleaning method on LFS that minimizes file fragmentation. During a cleaning process of LFS, our method sorts valid data blocks by inode numbers before copying the valid blocks to a new segment. This sorting re-locates fragmented blocks contiguously. Our cleaning method experimentally eliminates 60% of file fragmentation as compared to file fragmentation before cleaning. Consequently, our cleaning method improves sequential read throughput by 21% when read-ahead is applied.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.34 no.4
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• pp.629-639
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• 2024

CHAM is designed with an emphasis on encryption speed, considering that in the ISO/IEC standard block cipher operation mode, encryption functions are used more often than decryption functions. In the superscalar architecture of modern general-purpose processors, different ordering of operations can lead to different processing speeds, even if the computation configuration is the same. In this paper, we analyze the implementation efficiency and security of CHAM-like structures, which rearrange the order of operations in the ARX-based block cipher CHAM, for single-block and parallel implementations in a general-purpose processor environment. The proposed structures are at least 9.3% and at most 56.4%efficient in terms of encryption speed. The security analysis evaluates the resistance of the CHAM-like structures to differential and linear attacks. In terms of security margin, the difference is 3.4% for differential attacks and 6.8%for linear attacks, indicating that the security strength is similar compared to the efficiency difference. These results can be utilized in the design of ARX-based block ciphers.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.3A
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• pp.211-220
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• 2002

In this paper, we propose an efficient algorithm to compress simple computer cell animation at very low bit rate. The structure of proposed algorithm consists of intra frame coding and inter frame coding. In inter frame coding, animation is encoded by color quantization using a palette, rearrangement of index, ADPCM used in JPEG-LS, mapping, classification, and entropy coding. In interframe coding, classifying the characteristics of motion, animation is encoded by block based motion replenishment. Experimental results show that the proposed methods turns out to outperform conventional methods including Flash, FLC, Motion-JPEG, MPEG-1, and MPEG-4.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2012.06a
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• pp.237-239
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• 2012

이적작업은 자동화 컨테이너 터미널에서 하역작업의 생산성을 높이는 중요한 운영 전략 중의 하나이다. 이는 장치장 크레인의 이동시간과 재작업을 줄이기 위해 장치장 블록 내 컨테이너들의 재배치하는 작업을 의미한다. 이적작업은 주로 크레인의 유휴시간에 수행되며 장치장 크레인의 추가적인 하역 작업을 요구한다. 이적작업계획이 수립된 후 작업할당 문제가 다루어진다. 크레인 작업할당 문제는 작업가능시간에 대한 제약을 고려하여 이적작업의 효과를 최대화시키기 위해 장치장 크레인이 처리할 이적작업을 선정하고 이들의 작업순서를 정하는 것이다. 본 연구는 혼합정수계획법을 이용하여 장치장 크레인의 작업할당 문제를 모형화 하고 실효적인 이용을 위해 수치실험을 통해 여러 작업할당 규칙의 수행도를 비교분석하였다.

• Korean Journal of Computational Design and Engineering
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• v.16 no.3
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• pp.207-215
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• 2011

Due to its large size, a ship is first divided into scores of blocks and then each block is constructed through various shops, such as the assembly shop, the painting shop, and the outfitting shop. However, each block may not be directly moved to the next shop and may be temporarily laid on a block stockyard because the working time in each shop is different. If blocks are laid on the block stockyard without any planning, the rearrangement of the blocks by a transporter are required because the blocks have the different in and out time. In this study, an optimal layout method based on the genetic algorithm was proposed in order to minimize the rearrangement of the blocks in the block stockyard. To evaluate the applicability of the proposed method, it was applied to a simple layout problem of the block stockyard.

• Proceedings of the IEEK Conference
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• 2000.11c
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• pp.51-54
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• 2000

Due to the emerging of high-speed network, lots of interests of access to remote data have increased. Those interests motivate using of Cooperative Caching that uses remote cache like local cache by sharing other clients' cache. The conventional algorithm like GMS(Global Memory Service) has some disadvantages that occurred bottleneck and decreasing performance because of exchanges of many messages to server or manager. On the other hand, Hint-based algorithm resolves a GMS's server bottleneck as each client has hint information of all blocks. But Hint-based algorithm also causes some problems such as inaccurate information in it, if it has too old hint information. In this paper, we offer the policy that supplement bottleneck and inaccuracy； by using file identifier that can search for the lookup table and by exchanging oldest block information between each client periodically.

• Journal of Navigation and Port Research
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• v.30 no.6 s.112
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• pp.457-464
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• 2006

Remarshalling operation is one of the operations considered important in an automated container terminal to perform quickly loading operations and delivery operations. It arranges the containers scattered at a verticla yard block in order to reduce the transfer time and the rehandling time of ATC(Automated Transfer Crane)s. This paper deals with the remarshalling planning problem minimizing the weighted operation time. This problem can be decomposed into 2 subproblems, storage space assignment problem and operation sequencing problem Storage space assignment problem decides to where containers are transported in terms of transportation time cost.. With results of a previous subproblem, operation sequence problem determines the ATC operation sequence, which minimizes the dead-heading of ATC This study formulates each subproblem with mixed integer program and dynamic program. To illustrate the proposed model, we propose an instance to explain the process of remarshalling planning.