• Journal of the Korea Institute of Information Security & Cryptology
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• v.30 no.6
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• pp.1217-1223
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• 2020

The Block cipher CHAM is lightweight block cipher for low-end processors, developed by National Security Research Institute from Korea. The mode of operation is necessity for efficient operation of block cipher, among them, the counter (CTR) mode has good efficiency because it is easy to implement and supporting parallel operation. In this paper, we propose the optimized implementation for block cipher CHAM-CTR. The proposed implementation can be skipped some rounds by pre-computation. Thus it has better calculating speed than existing CHAM. Also, this implementation pre-load some of round keys to registers, before entering round functions. It makes reduced 160cycles loading time for round key load. Finally, proposed implementation achieved higher performance about 6.8%, and 4.5% for fixed-key scenario, and variable-key scenario, respectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.5A
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• pp.294-304
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• 2003

For an efficient software download in cellular CDMA systems, session admission control based on area (SACA) is presented. In the SACA scheme, the base station only allows mobile terminal to start session when the mobile locates near the base station of a cell. A mobile that is located near cell center can request software download session, but the mobile that is far away from the center can request session only after arriving near the cell center. Session duration time follows exponential and Pareto distribution. Performance is analyzed in terms of handoff rate, mean channel holding time, session blocking probability and handoff forced termination probability. As analysis results, handoff rate between cells in the proposed scheme is reduced to 30 ~ 250 % compared to conventional scheme, according to traffic characteristics such as terminal speed, session duration time and the size of the allowable zone area in a cell for the start of the session. And new session blocking probability slightly decreases to 5 ~ 20 %, but handoff session forced termination probability drastically decreases to 35 ~ 220 %.

• Proceedings of the Korea Information Processing Society Conference
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• 2004.11a
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• pp.709-712
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• 2004

응용프로그램이 복잡해지고 사용 환경이 다양해짐에 따라 신뢰성 높은 소프트웨어 생산을 위한 테스트가 중요시 되고 있다. 소프트웨어를 테스트하기 위해서는 각 기능에 따라 동작하는 모듈이 합당한 동작에 대해서 분석해야한다. 모듈은 다수의 실행경로로 이루어져 있으며 각 실행 경로에 따라 다른 결과를 출력하도록 설계되어 있다. 본 논문은 실행 경로에 따른 모듈의 인자를 자동으로 생성할 수 있는 방법을 제안한다. 프로그램은 블록간의 제어문 결합으로 이루어져 있고 다른 실행 경로를 생성하는 요인은 프로그램내의 제어문을 통해 결정된다. 그러므로 블록간의 결합을 제어의 종류에 따라 연산으로 표현하고 연산의 특성을 분석한다. 그리고 블록의 속성은 조건식을 가지고 있어 블록이 실행되는 조건을 표현한다. 각 연산의 특성에 맞게 조건식을 연산하여 블록이 동작하는 조건을 확인하고 최종적으로 실행 경로에 따른 모듈의 인자를 구하는 방법을 제안한다. 이 방법은 조건식에 영향을 주는 명령만을 추출하는 방법으로 인자를 구하기 위한 계산의 로드를 줄이는 장점이 있다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.10
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• pp.1-7
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• 2003

In this paper, we propose load balanced routing and wavelength assignment (RWA) algorithm for static model. The proposed algorithm arranges the routing paths over the link uniformly and assigns routing paths according to the length of routing paths orderly. Thus, the proposed algorithm can efficiently utilize the network resources. Through the computer simulation on layered-graph model, we prove that the proposed algorithm improves network throughput and reduces blocking probability comparing to first-fit algorithm [1］. Moreover, the proposed algorithm considerably reduces computational time.

• Journal of KIISE:Computer Systems and Theory
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• v.37 no.2
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• pp.90-102
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• 2010

Flash memory has been widely used as an important storage device for consumer electronics. For the flash memory-based storage systems, FTL (Flash Translation Layer) is used to handle the mapping between a logical page address and a physical page address. Especially, log buffer-based FTLs provide a good performance with small-sized mapping information. In designing the log buffer-based FTL, one important factor is to determine the mapping structure between data blocks and log blocks, called associativity. While previous works use static associativity fixed at the design time, we propose a new log block mapping scheme which adjusts associativity based on the run-time workload. Our proposed scheme improves the I/O performance about 5~16% compared to the static scheme by adjusting the associativity to provide the best performance.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.304-305
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• 2018

Recently, Industrial-IoT (IIoT) solutions accounted for up to 55% in 2016 and technological innovation and various new business models are being developed. In this paper, apply IIoT device in various environments and implement an ontology system that can interwork with block type IIoT device to easily add / change / delete sensor. The proposed system consists of IIoT device, block-type module, and ontology server. When the block-type module is connected to the IIoT device, the appropriate driver is installed and the firmware is downloaded through the ontology server. Even if a block is added / changed / deleted, it can be updated automatically. Through experiments, we confirmed that the normal operation of the server and the updating and downloading of software are implemented normally.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.12
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• pp.2179-2187
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• 2008

The P2P technology has been widely used to distribute files efficiently, and its use in streaming is rapidly increasing. P2P streaming has issues about startup-delay, scalability, and real-time playback, however, what affects these factors has not been researched sufficiently. This paper suggests a buffering model for progressive download within mesh-based P2P system, which corresponds to downloading and playing the content at the same time. It is used to analyze PDF(Playback Deadline First), Rarest algorithms which are block-selection strategies of P2P streaming and proposes a mixed selection of them. The mixed block selection strategy dynamically performs different strategies based on whether the blocks to be played are received or not. In consequence, it enhances the QoS of streaming in a single peer point of view, as well as improving block distributions in an overlay network.

• Journal of the Korea Society of Computer and Information
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• v.19 no.10
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• pp.81-89
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• 2014

In this paper, we propose SA hash algorithm to avoid upload identical files and design server system using proposed SA hash algorithm. Client to want to upload file examines the value of SA hash and if the same file is found in server system client use the existing file without upload. SA hash algorithm which is able to examine the identical-file divides original file into blocks of n bits. Original file's mod i bit and output hash value's i bit is calculated with XOR operation. It is SA hash algorithm's main routine to repeat the calculation with XOR until the end of original file. Using SA hash algorithm which is more efficient than MD5, SHA-1 and SHA-2, we can design server system to avoid uploading identical file and save storage capacity and upload-time of server system.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2006.10a
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• pp.39-42
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• 2006

본 논문에서는 블록터보로드를 사용하는 OFDM 시스템에서 오류정정 능력을 향상시키기 위하여 블록터보코드를 디코딩하는데 있어 채널상태정보(CSI)를 이용하는 새로운 알고리듬을 제안한다. 새로운 디코딩 알고리듬은 레일레이 페이딩 환경에서 채널정보를 사용하지 않는 기존의 디코딩 알고리듬과 비교를 하였으며 실험결과 새롭게 제안된 시스템의 경우 1 회 반복 복호에서 CSI 값을 적용하지 않은 기존의 복호 시스템의 4 회 반복 복호한 경우보다도 $3.SdB\;{\sim}\;5dB$의 성능 향상을 보임으로써 반복 복호의 시간을 70% 이상 감소시킬 수 있었다. 따라서 블록터보코드를 반복 복호하는 경우에 CSI 값을 적용한 시스템이 뛰어난 성능 향상과 더불어 반복 복호 시간을 줄임을 알 수 있었다.

• Proceedings of the Korean Information Science Society Conference
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• 1999.10c
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• pp.411-413
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• 1999

본 논문에선느 ATM 통신망을 위한 여러 ATM 스위치 모델들 중에서, 내부적으로 블록킹(blocking)이 없고 입출력 단에 각각 버퍼가 할당되어 있는 입출력 버퍼형 교환기에 대하여 연구하였다. 기존에서 스위치 스피드-업(Switch Speed-up) 기법하에서 주로 연구가 이루어졌다. 따라서, 본 논문에서는 유니폼 트래픽하에서 Output-port Expansion 기법을 사용한 귀환.손실 모드 및 하이브리드 모드하에서의 셀 손실률을 비교 분석하였다. Output-port Expansion 기법은, 한 타임 슬롯동안에 입력포트 당 하나의 셀만 교환되며, 만약 하나 이상의 셀들이 같은 출력포트로 향하면, 최대 교환되는 셀 수를 K(Output-port Expansion Ratio)개로 제한하는 방식이다. 유니폼 트래픽(uniform random traffic) 하에서 각 모드에 따른 셀 손실률을 비교 분석한 결과, 로드 0.9를 기점으로, 0.9이하의 로드에서는 하이브리드 모드가, 0.9이상의 로드에서는 손실모드가 가장 낮은 셀 손실률을 보인다.