• Proceedings of the Korea Information Processing Society Conference
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• 2004.05a
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• pp.1157-1160
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• 2004

현재 사용되고 있는 대부분의 메신저는 서버에 로그 온할 때 패스워드를 RC5등으로 암호화해서 보내지만 패스워드 크래킹 프로그램들이 많이 알려져 있어 안전하지 못하다. 또한 로그 온한 후 통신하는 두 호스트들 간의 전송되는 정보가 아무런 보호 장치 없이 네트워크를 통해 전송되어 제3자에 의한 도청이 가능하게 된다. 따라서 전송되는 정보의 암호화를 포함하는 안전한 메신저 서비스의 필요성이 대두되고 있다. 본 논문에서 제안된 안전한 메신저는 동일한 키 사이즈를 갖는 다른 공개키 암호체계보다 훨씬 강하다고 알려져 있는 타원곡선 암호체계를 이용하여 빠르고 효율적이며 높은 안전도를 나타내는 패스워드 키 교환 방식을 설계하였고, 사용자간에 IPSec프로토콜을 사용하여 효율적인 데이터 전송이 가능하고 또한 보안성을 높이기 위한 방법으로 Host-to-Host간의 데이터가 인터넷에서 가상의 파이프를 통해 전달되도록 터널 모드를 제시하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2022.05a
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• pp.187-190
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• 2022

PDF (Portable Document Format)는 1992년 Adobe 에서 개발한 파일 형식으로 ISO 32000 으로 표준화 되어 전세계적으로 사용되고 있다. PDF와 같이 주로 사용되는 파일은 암호 해독(Password Cracking)의 대상이 될 수 있다. 본 논문에서는 PDF 1.4-1.6 암호 해독을 위해 CUDA GPU 상의 최적 구현하였다. 암호 해독에 사용되는 MD5와 RC4 알고리즘의 최적화와 CUDA GPU의 요소를 사용하였으며 RTX 3060 환경에서 크래킹 도구 해시캣과 비교하여 22.5%의 성능 향상을 달성하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2021.11a
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• pp.263-266
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• 2021

GPU 상에서의 효율적인 암호 구현을 위해서는 GPU 내부의 자원인 메모리와 명령어셋을 구현하고자 하는 암호 구조에 맞추어 사용하는 것이 중요하다. 본 논문에서는 Blowfish와 RC4를 최신 GPU 프로세서 상에서 최적 구현해 보고 성능을 저하시키는 요인들과 향상시키는 요인들을 비교 분석한다. 특히 파일암호화와 패스워드 크래킹에서 발생하는 암호화 구현 고려 사항에 대해 확인하며 해당 특징이 GPU 암호 구현 상에서 미치는 영향에 대해 확인해 보도록 한다. 마지막으로 앞에서 구현한 결과물의 성능을 저하시키는 요소에 대한 분석을 기반으로하여 높은 GPU 내성을 가지는 암호 설계를 위해 필요한 구조에 대해 확인해 보도록 한다.

• Journal of the Korean Applied Science and Technology
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• v.35 no.3
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• pp.731-743
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• 2018

In bio-jet fuel production, selecting operating conditions of hydro-upgrading is of great importance to make iso-Paraffin rich hydrocarbons with carbon distribution including jet fuel range. Herein, iso-Paraffin rich biofuel including jet fuel range hydrocarbons ($C_8-C_{16}$) is produced from simultaneous cracking and isomerization using n-Paraffin rich hydrocarbon derived from hydrotreated vegetable oil over 0.5 wt..% Pt/Zeolite catalyst. We report and analyze the yields and compositions in the produced hydrocarbons affected by various operating conditions, such as reaction temperature, reaction pressure, molar ratio of reactants, and weight hourly space velocity. Aforementioned operating conditions not only can help interpret the reaction dynamics of hydro-upgrading, but also further produce bio jet-fuel after distillation.

• Journal of Adhesion and Interface
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• v.16 no.1
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• pp.29-34
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• 2015

Hydrocarbon resins, which are defined as low molecular weight, amorphous, and thermoplastic polymers, are widely used as tackifier for various types of adhesives, as processing aids in rubber compounds, and as modifiers for plastics polymers such as isotactic polypropylene. Typically, hydrocarbon resins are non-polar, and thus highly compatible with non-polar rubbers and polymer. However, they are poorly compatible with polar system, such as acrylic copolymer, polyurethanes, and polyamides. Moreover, recently the raw materials of hydrocarbon resin from naphtha cracking had been decreased because of light feed cracking such as gas cracking. To overcome this problem, in this study, novel hydrocarbon resins were designed to have a highly polar chemical structure which material is sustainable. And, it was successfully synthesized by Diels-Alder reaction of dicyclopentadiene monomer and sorbic acid from blueberry as renewable resources. Acrylic resins were formulated with various tackifiers solution including sorbic acid grafted hydrogenated dicyclopentadiene hydrocarbon resins in acrylic adhesive and rolling ball tack, loop tack, $180^{\circ}$ peel adhesion strength, and shear adhesion strength were measured. The properties depend on the softening point and polar content of tackifiers.

• Applied Chemistry for Engineering
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• v.30 no.3
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• pp.297-302
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• 2019

In order to investigate structural changes of the pyrolysis fuel oil (PFO), the volatile matters and heavy oil fractions were separated from PFO by heat treatment temperature. As a result of $^1H-NMR$ analysis of volatile matters, 1~2 ring aromatic compounds contained in the petroleum residue were mostly removed at a temperature before $340^{\circ}C$. Moreover, new peaks corresponding to aliphatic hydrocarbons were detected at the chemical shift of 2.0~2.4 ppm. It is attributed that the aliphatic hydrocarbon sidechain was cracked from the aromatic compound by the cracking reaction occurred at $320^{\circ}C$. The C/H mole ratio and aromaticity increased with increasing the heat treatment temperature. Therefore, from the structural analysis results of heavy oil fractions and volatile matters from PFO, the decomposition of the aliphatic sidechain by cracking reaction and the separation of volatile matters by boiling point of components were mostly affected structure changes of the PFO.

• The Journal of the Korea institute of electronic communication sciences
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• v.4 no.3
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• pp.217-223
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• 2009

Recently, the development of the various network method can generate serious social problems. So, it is highly required to control security of network. These problems related security will be developed and keep up to confront with anti-security field such as hacking, cracking. The way to preserve security from hacker or cracker without developing new cryptographic algorithm is keeping the state of anti-cryptanalysis in a prescribed time by means of extending key-length. In this paper, the proposed montgomery multiplication structured unit array method in carry generated part and variable length multiplication for eliminating bottle neck effect with the RSA cryptosystem. Therefore, this proposed montgomery multiplier enforce the real time processing and prevent outer cracking.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.427-427
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• 2012

Cu(In,Ga)$Se_2 $ (CIGS) 박막 태양전지는 높은 효율과 낮은 생산 단가로 인해 많은 연구가 이루어지고 있다. 특히, Se flux는 박막의 특성에 가장 중요한 CIGS의 결정성, 결정립 크기, 결정방향을 형성하는데 영향을 주는 것으로 알려져 있다. 일반적인 co-evaporation에 사용되는 Se effusion cell의 경우, 높은 분자가를 가지는 Se 분자들이 공급되기 때문에 낮은 반응성을 보이지만 Se cracker cell을 사용할 경우 Se 분자들이 열적으로 크래킹되어 낮은 분자가를 가지므로 화학적으로 높은 반응성을 가진다. 따라서 적은 양의 Se으로도 양질의 CIGS 박막 제작이 가능하다. 본 연구에서는 Se effusion cell과 cracker cell을 이용하여 CIGS 광흡수층을 제작하였으며, 각각 제작된 CIGS 박막의 특성을 비교하였다. 또한 Se cracker cell의 reservoir zone(R-zone) 온도를 통해 Se flux를 변화시켜 Se flux에 따른 CIGS 박막 태양전지의 특성에 대해 알아보았다. SEM, EDS, XRD 측정을 통해 박막의 특성을 분석하였고, J-V 측정을 통해 태양전지의 특성에 대해 알아보았다. Se cracker를 사용하여 제작된 CIGS 박막의 결정립 크기가 effusion cell로 제작된 박막보다 더 크게 나타났고, Se flux가 증가할수록 결정립의 크기는 증가하였다. Se cracker의 flux가 $0.17{\'{{\AA}}}$/s일 때 반사방지막 없이 13.14%의 효율을 나타내었다.

• Journal of the Korea Society of Computer and Information
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• v.6 no.2
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• pp.90-96
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• 2001

The development of network and the other communication-network can generate serious social problems. So. it is highly required to control security of network. These problems related security will be developed and keep up to confront with anti-security part such as hacking. cracking. In this paper. the proposed multiple nonlinear S-box function which is capable to cipher regardless of key distribution or key-length for these definite problem is proposed and designed in hardware. The proposed multiple nonlinear S-box function increase secret level from using a nonlinear function in multiply for key data utilized in cryptography that generates MDP and MLP in maximum is proposed to prevent cryptography analysis. The designed the multiple nonlinear S-box function in this paper performed synthesization and simulation using Synopsys Ver. 1999.10 and VHDL

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.6
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• pp.2713-2717
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• 2011

To transmit data from straggling sensors in water-processing basic industries etc., used Binary-CDMA system has safety voluntarily. But Binary-CDMA is necessity that react very sensitively in environment change as defense about hacking and cracking of various way that change suddenly. Therefore, this paper is that see added cryptographic algorithm for safety and easy update on correlator that a bottle-neck phenomenon is happened in Binary-CDMA to solve problem that is such. Added cryptographic algorithm does to communicate safe information in channel that is not safe as that achieve 1:1 confrontation for sensors by symmetric cryptographic algorithm.