• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.4C
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• pp.454-461
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• 2007

The next-generation computer is the ultra-lightweight mobile computer that communicates with peripheral handhold devices and provides dynamically the services appropriate to user. To provide the dynamic services on the ultra-lightweight mobile computer, security problem for user or computer system information should be solved and security mechanism is necessary for the ultra-lightweight mobile computing environment that has battery limit and low performance. In this paper, the security mechanism on the component based middleware for the ultra-lightweight mobile computer was implemented using RC-5 cipher algorithm and SHA-1 authentication algorithm. The security components are dynamically loaded and executed into the component based middleware on the ultra-lightweight mobile computer.

• Journal of Korean Society of Forest Science
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• v.63 no.1
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• pp.12-20
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• 1984

This research was performed to estimate the properties of particleboard based on the press time and temperature which was made of chip of larch that grows in Korea. The results in this study were as follows: 1) Even though the chips, 1:1-35 ratio between length and thickness, are relatively bad condition, the surface smoothness that can easily spread the adhesive evenly and thoroughly and bonding ability of chips can give proper physical properties. 2) It shows more mechanical properties at the press time of 10 min. in MOR (Modulus of Rupture), MOE (Modulus of Elasticity) and SHA (Screw Holding Ability). 3) It is not significant according to the press time 20 min. in MOR, IBS (Internal Bonding Strength) and SHA, for the reciprocal actions between the accelerating aging effect of chip and the softening effect of adhesion are occured. 4) IBS is rising according to the increasing temp at the press time of 10 min. Because it needs to transfer the plate heat to make the proper hardening temp. In the layer. 5) The heat treatment effects have greatly influenced the stahility of dimension by falling the absorption, anisotropy and inhomegenity. As a result of these the values of thickness and linear expansion ratio were respectively dropped by the increase of press temp and the time and so did absorption.

• 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.

• Journal of Advanced Navigation Technology
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• v.20 no.1
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• pp.72-78
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• 2016

MD-5 has been the hash algorithm to encrypt the user's password on Linux from the beginning. Recently the more reliable password management was demanded and SHA-512 algorithm became the hash algorithm on the recent Enterprise Linux which is more reliable than MD-5. This paper researching the characteristics of the hashing and encryption algorithms and find out about Linux User information management. Based on this analysis, and analysis of the security of the hashing algorithm is applied to the user password. In addition, analyzes the cases used hash algorithm applied to the validation of Open Source Software file, such as Apache, PHP, MySQL. Finally, by analyzing the security tool John The Ripper this paper suggests the enhanced security with the administrative management of passwords.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.14 no.3
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• pp.107-115
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• 2004

SHACAL-2 is a 256 bit block cipher with various key sizes based on the hash function SHA-2. Recently, it was recommended as one of the NESSIE selections. UP to now, no security flaws have been found in SHACAL-2. In this paper, we discuss the security of SHACAL-2 against an impossible differential attack. We propose two types of 14 round impossible characteristics and using them we attack 30 round SHACAL-2 with 512 bit 18y. This attack requires 744 chosen plaintexs and has time complexity of 2$^{495.1}$ 30 round SHACAL-2 encryptions.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.05a
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• pp.143-146
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• 2011

A 50-MS/s 10-bit pipelined ADC with 1.2Vpp differential input range is proposed in this paper. The designed pipelined ADC consists of eight stage of 1.5bit/stage, one stage of 2bit/stage, digital error correction block, bias & reference driver, and clock generator. 1.5bit/stage is consists of sub-ADC, DAC and gain stage, Specially, a sample-and hold amplifier (SHA) is removed in the designed pipelined ADC to reduce the hardware and power consumption. Also, the proposed bootstrapped switch improves the Linearity of the input analog switch and the dynamic performance of the total ADC. The reference voltage was driven by using the on-chip reference driver without external reference. The proposed pipelined ADC was designed by using a 0.18um 1-poly 5-metal CMOS process with 1.8V supply. The total area including the power decoupling capacitor and power consumption are $0.95mm^2$ and 60mW, respectively. Also, the simulation result shows the ENOB of 9.3-bit at the Nyquist sampling rate.

• Journal of Korean Society on Water Environment
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• v.22 no.1
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• pp.140-144
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• 2006

This study was performed to investigate the effect of organic characteristics and feed water solution chemistry on membrane fouling index such as Silt Density Index (SDI) and Modified Fouling Index (MFI). Specifically, Aldrich humic acids (AHA) and Suwannee river humic acids (SHA) were used in SDI/MFI experiments. Higher SDI values were observed with increasing organic concentration. AHA with larger molecular weight (MW) and SUVA (${\approx}UV_{254}/TOC$) resulted in higher SDI values, compared to SHA. The feed solution chemistry (i.e, pH, ionic strength, and hardness) also affects SDI values to some degree. In particular, SDI increased with increasing hardness ($Ca^{2+}$) concentration for AHA. Unlike SDI, the MFI developed on the basis of particle cake filtration theory, was not accurately assessed due to internal fouling by organics such as pore adsorption and subsequent pore blocking.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.123-125
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• 2004

The importance for Internet security has being increased and the Internet Protocol Security (IPSec) standard, which incorporates cryptographic algorithms, has been developed as one solution to this problem. IPSec provides security services in IP-Layer using IP Authentication Header (AH) and IP Encapsulation Security Payload (ESP). In this paper, we propose IPSec cryptographic processor design based AMBA architecture. Our design which is comprised Rijndael cryptographic algorithm and HAMC-SHA-1 authentication algorithm supports the cryptographic requirements of IP AH, IP ESP, and any combination of these two protocols. Also, our IPSec cryptographic processor operates as AMBA AHB Slave. We designed IPSec cryptographic processor using Xilinx ISE 5.2i and VHDL, and implemented our design using Xilinx's FPGA Vertex XCV600E.

• Proceedings of the Korean Information Science Society Conference
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• 2011.06a
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• pp.539-542
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• 2011

TAR와 같은 아카이브 포맷에는 파일 중복을 제거하는 기능이 포함되어 있지 않아서 리눅스 배포 미러와 같이 버전단위로 저장되는 시스템에서 디스크 공간의 낭비가 발생하였다. 본 연구에서는 파일 중복 제거 기능을 추가한 TAR형태의 압축 포맷인 DTAR와 이를 제어하는 DTM 유틸리티를 제안하였다. 주요 아이디어는 클라이언트에서 DTAR 생성 시, 헤더에 SHA1 해시 정보를 추가하여 DTM 유틸리티를 통해 SHA1 해시를 노드로 하는 R-B Tree를 생성하고 이를 서버에 저장된 해시 정보와 비교하여 DTAR내에서 중복이 없는 파일을 선택적으로 파일을 압축하고 서버로 백업하고 관리하는 것이다. 실험 결과 DTM을 통한 백업은 중복 데이터가 누적될수록 DTAR가 tar.gz보다 공간적인 측면이나 백업을 위한 데이터 패킷 전송 시간에서 크게 향상된 성능을 보였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.393-396
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• 2007

언제, 어디서나, 누구라도 컴퓨터와 네트워크를 통해 손쉽고, 편리하게 서비스를 제공 받을 수 있도록 컴퓨터를 실생활 환경 속에 편재시키는 유비쿼터스 컴퓨팅(Ubiquitous Computing)은 차세대 컴퓨팅을 주도할 개념으로 급부상하고 있다. 이러한 환경 속에서 안전하게 서비스를 이용할 수 있는 환경은 매우 중요하다. 그러나 유비쿼터스 환경을 구축하는 대부분의 센서 노드들은 초소형, 초경량의 제한된 자원을 가지고 있어, 기존의 무선 네트워크에서 사용된 기술을 그대로 사용할 수 없다. 따라서 최소한의 자원을 사용하는 보안 기술개발이 필요하다. 본 논문에서는 기존의 SHA1알고리즘을 센서 네트워크에서 사용할 수 있도록 경량화하여 적용해 보았다. 각 노드에서 센서 값을 취득하여 디지털로 변환하고 무선 통신으로 전송하기 전에 인증 알고리즘을 거쳐서 생성된 인증값을 보내려는 데이터에 추가하여 전송한다. 이 데이터를 받은 노드에서는 동일한 알고리즘으로 인증 값을 생성하고 받은 인증값과 비교하여 데이터의 인증 절차를 수행한다. 이렇게 함으로써 데이터의 정확성이나 무결성을 보장할 수 있다.