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劉承宰,崔允碩,金正九 대한금속재료학회 2002 대한금속·재료학회지 Vol.40 No.6
The purpose of the present investigation was to study the stress corrosion cracking (SCC) properties of environmentally friendly Bi-brasses in Mattsson's solution (0.05M copper sulfate and 0.5M ammonium sulfate, pH 7.4) at room temperature. Three unleaded brasses with Bi content ranging from 1 to 3 wt% and a conventional leaded brass for comparison were investigated. The effect of Bi on SCC of unleaded brasses was studied through polarization test, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM, energy dispersive spectroscopy (EDS) and slow-strain-rate test (SSRT). Potentiodynamic polarization studies indicated that the corrosion resistance of Bi-containing brasses was improved as the content of Bi, which showed a passivating characteristic in Mattsson's solution, increased. The Pb- and Bi-containing brasses presented an inductive behavior on impedance data in low frequency region at the open-circuit potential (OCP). Such behavior could be attributed to the adsorption process on the alloy surface. The observed dezincified layers after SSRT should be particularly good initiators of SCC as they could induce tensile stress. As the content of Bi increased, the thickness of dezincified layer and the volume fraction of preferentially attacked Β phase decreased, therefore, SCC resistance of the Bi-containing brasses was improved.
A Study on IoT Devices Vulnerability and Security
유승재,Yoo, Seung Jae Korea convergence Security Association 2021 융합보안 논문지 Vol.21 No.1
수많은 IoT기기들이 시공간의 제약이 없는 유무선 네트워크 환경으로 연결되어 데이터를 수집 및 전송하는데, 그로 인해 많은 보안상의 취약점이 노출되고 있다, 그러나 IoT 보안은 디바이스와 네트워크의 접근방식이나 구현방식의 차이로 인해 실현가능한 보안표준과 장치인증을 생성하는 것이 쉽지 않다. 디바이스의 보안레벨 강화를 위한 표준 프레임워크의 개선과 적용이 가장 성공적인 보안효과를 거들 수 있는 출발점이라는 것은 분명한 사실이다. 이 연구에서는, IoT 디바이스에 대해 정보보안의 기본 목표인 기밀성, 무결성, 가용성 그리고 접근통제를 확보할 수 있도록 하는 IoT디바이스에 대한 표준화된 보안성 평가기준을 조사하고, 그 개선방안을 연구하고자 한다. Numerous IoT devices are connected to a wireless network environment to collect and transmit data without time and space limitations, but many security vulnerabilities are exposed in these process. But IoT security is not easy to create feasible security standards and device authentication due to differences in the approach or implementation of devices and networks. However, it is clear that the improvement and application of the standard framework for enhancing the security level of the device is the starting point to help the most successful security effect. In this study, we investigate the confidentiality, integrity, availability, and access control implementation plans for IoT devices (which are the basic goals of information security), and standardized security evaluation criteria for IoT devices, and study ways to improve them.
개방 순환 냉각 시스템용 환경 친화적 부식, 스케일 및 미생물 혼합억제제 개발
유승재,김정구,최동진 대한금속재료학회 2002 대한금속·재료학회지 Vol.40 No.2
The use of heavy metal-based corrosion inhibitors is increasingly being curtailed by recent environmental restrictions. In many parts of the world, high levels of inorganic phosphates are also restricted by law. In response to these environmental guidelines, this paper presents the results of a "green" chemicals study that was undertaken to investigate the ability of a new inhibitor to inhibit the corrosion, scale and microorganism problems found in open recirculating cooling systems. This study used a new all-organic multi-component inhibitor blend composed of citric acid/ phosphonates/ acrylate copolymer/ isothiazolone. The effects of the inhibitor on carbon steel dissolution in synthetic cooling water were studied through weight loss measurements and electrochemical, scale, and microorganism tests. The results obtained from this study show that the new inhibitor can decrease corrosion, scale build-up and microbial growth under the conditions tested. Potentiodynamic polarization curves indicate that the blended inhibitor acted as an anodic inhibitor, reducing metal dissolution. The nature of protective films formed on the carbon steel was studied by scanning electron microscopy (SEM) and auger electron spectroscopy (AES). The inhibition effects are due to the formation of protective films which might contain calcium phosphonates and iron oxide. The inhibitor used in this study appears to have an excellent crystal modification effect on calcium carbonate scale. The various microorganisms used in this study were inhibited effectively in the planktonic state.
유승재 한국융합보안학회 2019 융합보안 논문지 Vol.19 No.4
Data security is the planning, implementation and implementation of security policies and procedures for the proper audit and authorization of access to and use of data and information assets. In addition, data serviced through internal / external networks, servers, applications, etc. are the core objects of information protection and can be said to focus on the protection of data stored in DB and DB in the category of information security of database and data. This study is a preliminary study to design a proper Data Security Management System (DSMS) model based on the data security certification system and the US Federal Security Management Act (FISMA). And we study the major security certification systems such as ISO27001 and NIST's Cybersecurity Framework, and also study the state of implementation in the data security manager solution that is currently implemented as a security platform for preventing personal data leakage and strengthening corporate security 데이터보안(Data Security)이란 데이터 및 정보자산의 접근, 활용에 대한 적절한 인증과 권한의 감사를 위하여 보안정책 및 절차를 기획, 구축, 실행하는 것이다. 또한 내・외부 네트워크, 서버, 어플리케이션 등을 통해 서비스되는 데이터는 정보보호의 핵심 대상으로서 데이터베이스와 데이터의정보보안의 범주에서 DB와 DB내에 저장된 데이터의 보호에 특화하여 집중하는 것이라 할 수 있다. 이 연구에서는 데이터보안 인증체계와 미국의 연방보안관리법(FISMA)을 기반으로 한 적절한 데이터보안관리체계(DSMS, Data Security Management System) 모델 설계를 위한 기초연구를 진행한다. ISO27001, NIST의 Cybersecurity Framework 등 주요보안인증 제도를 살펴보고 또한 현재 개인데이터 유출방지와 기업보안강화를 위한 보안플렛폼으로 구현된 데이터보안매니저 솔루션에 구현된 상태를 연구한다.