• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2017년도 춘계학술대회
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• pp.747-749
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• 2017

악성코드 감염, 외부침입 등으로 인한 금융회사의 고객정보 유출, 기타 금융사고 발생에 대한 위험으로부터 금융거래를 보호하기 위해 금융위원회에서는 "금융전산 보안강화 종합대책"에서 업무망과 인터넷망 분리에 의한 안전한 금융거래와 고객정보 보호대책의 가이드라인을 제시하고 금융전산망 분리를 의무화시켰다. 이에 각 금융회사는 회사별 IT전산 환경에 맞는 물리적, 논리적 망분리 방법을 선택하여 망분리 시스템을 구축하고 있다. 본 논문은 전통적 범용장비의 구성과 최근 발전중인 가상화 기술 중 하나인 Hyper Converged를 통한 통합형 HCI(Hyper Converged Infrastructure) 방식에 대한 비교 및 사례 연구로 논리적 망분리 구축을 위한 효율적인 인프라 구성 방안을 제시한다.

• 한국인쇄학회지
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• 제16권3호
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• pp.29-41
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• 1998

The ultraviolet(UV)-curable materials wildly have been used as a ink and coating materials. A according to measure UV polymerization phase separation of acryl groups 2,3,4-functional monomer, a few experiments were performed gel fraction, dynamic viscosity of alkyd resin blend system. Dependence of photoiniator concentration and various monomer, alkyd resin content investigated structural changes of films cured by UV irradiation. Curing rate measured UV irradiation under $25^{\circ}C$, cell gap 7cm and film thickness 100${\mu}{\textrm}{m}$. In results, it was through that the viscoelastic properties of films cured with increasing the ratios of monomer/alkydresin contents are network polymer in properties such as viscoelasticity.

• 한국인쇄학회지
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• 제13권1호
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• pp.93-104
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• 1995

Liquid crystal-polymer composite(LCPC) films promising new materials for both projection displays and vision product. LCPC films consist of a continous liquid crystal phase embedded in a three- dimensional network of polymer matrix. The liquid crystal in these LC phases can be elecrtrically switched giving rise to an opaque scattering off-stats and a transparent, non-scatting on- stats. In this work. a premixture is composed of LC, UV-curable monomer and photonitiator. LCPC films are formed by photopolymerization induced phase separation from this premixture. In conclusion, structure and electro-optical properties of LCPC films strongly depends on the selection of monomer, LC content and curing rate.

• 제어로봇시스템학회논문지
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• 제10권2호
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• pp.112-124
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• 2004

A neural network based adaptive reconfigurable flight controller is presented for a class of discrete-time nonlinear flight systems in the presence of variations of aerodynamic coefficients and control effectiveness decrease caused by control surface damage. The proposed adaptive nonlinear controller is developed making use of the backstepping technique for the angle of attack, sideslip angle, and bank angle command following without two time separation assumption. Feedforward multilayer neural networks are implemented to guarantee reconfigurability for control surface damage as well as robustness to the aerodynamic uncertainties. The main feature of the proposed controller is that the adaptive controller is developed under the assumption that all of the nonlinear functions of the discrete-time flight system are not known accurately, whereas most previous works on flight system applications even in continuous time assume that only the nonlinear functions of fast dynamics are unknown. Neural networks learn through the recursive weight update rules that are derived from the discrete-time version of Lyapunov control theory. The boundness of the error states and neural networks weight estimation errors is also investigated by the discrete-time Lyapunov derivatives analysis. To show the effectiveness of the proposed control law, the approach is i]lustrated by applying to the nonlinear dynamic model of the high performance aircraft.

• 대한의용생체공학회:의공학회지
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• 제29권6호
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• pp.502-511
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• 2008

This study was designed to develop a new algorithm to extract the voluntary EMG and the evoked EMG from a mixed EMG generated when the muscle is stimulated both voluntarily and by electrical stimulation in the FES system. The proposed parallel filter algorithm consists of three phases: (1) Fourier transform of the mixed EMG, (2) multiplication of the transformed signal to two frequency functions, and (3) inverse Fourier transform. Four incomplete spinal cord injured patients participated in the experiments to evaluate the algorithm by measuring the knee extensor torque and the EMG signals from the quadriceps. Two functions of the algorithms were evaluated: (1) extraction of the evoked EMG and (2) the voluntary EMG from the mixed EMG. The results showed that the algorithm enabled us to separate the two EMG components in real time from the mixed EMG. The algorithm can and will be used for estimating the voluntary torque and the evoked torque independently through an artificial neural network based on the two EMG components, and also for generating a trigger signal to control the on/off time of the FES system.

• 한국초전도ㆍ저온공학회논문지
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• 제6권2호
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• pp.11-14
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• 2004

YBCO thin films have good characteristics for current limiting materials due to compact size and high current carrying capability. But the irregularities and the extreme thin thickness of YBCO films cause some difficulties in simultaneous quench and thermal shock protection. In order to solve these problems, vertical magnetic field generated from solenoid coil was applied to the YBCO element. And also to minimize the inductance caused by the serial connection of magnetic field source with superconducting elements, magnetic field source was separated from the power lines adapting protective current transformer. In this study, electric field-current (E-I) and quench characteristics of YBCO films were analyzed both by electrical measuring method and observations of bubble propagation. From the experiment results, it was revealed that the magnetic fields generated by surrounding coil could induce the uniform quench distribution for all stripes of current limiting units and finally simultaneous quenches were realized in all serial connection of YBCO elements. In addition, the separation of magnetic field source form electrical network could be good solution for simultaneous quench of YBCO films without any unnecessary effect caused by serial connection.

• 정보보호학회논문지
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• 제25권3호
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• pp.703-713
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• 2015

기존의 EMS/SCADA에서 제어시스템과 필드디바이스 간의 연계시스템은 데이터의 신뢰성을 높이기 위해서 외부 네트워크와의 망 분리를 통한 접근 통제를 하였지만 현재는 운영의 효율성 증대와 체계적 관리, 경제적 측면을 고려한 외부 망과의 연결 필요성이 증가하고 있는 추세이다. 이런 발전한 연계구간은 과거에 비해 더 많은 보안 취약점을 갖게 되었으며, EMS/SCADA 연계구간에서의 통신은 특별한 관리 방법이 필요하다. 본 논문에서는 국내 환경을 고려하여 EMS/SCADA 연계구간에서 주로 사용되는 시리얼 DNP3와 TCP/IP기반 DNP3를 적용한 보안성 평가 인증기술을 제시하였다. 제시하는 보안성 평가 인증기술은 자원 안전성 테스트와 악성 패킷 테스트 2가지 세부 평가로 나누어 안전성을 평가하며 각각의 보안 요구사항 및 평가방법을 도출하여 기존의 평가 인증 기술들과의 차별성을 제시하고자 하였다.

• International Journal of Computer Science & Network Security
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• 제24권4호
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• pp.206-210
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• 2024

Industrial facilities that use modern IT technologies require the ensured reliability and security of information in automated enterprise management. Concurrently, so as to ensure a high quality of communication, it is necessary to expand the bandwidth of communication channels, which are limited by the physical parameters of the radio frequency spectrum. In order to overcome this contradiction, we propose the application of technology fundamental to ultra-wideband signals, in which the ratio between the bandwidth and its central part is greater than "one". For this reason, the information signal is emitted without a carrier frequency - simultaneously within the entire frequency band - provided that the signal level is lower than the noise level. For the transmission of information content, the method of positional-time coding is used, in which each information bit is encoded by hundreds of ultrashort pulses that arrive within a certain sequence. Mathematical models of signals and values observed in wireless communication systems with autocorrelation reception of modulated ultra-wideband signals are furthermore recommended. These assist in identifying features of the dependence of the error probability on the normalized signal-to-noise ratio and the signal base. Comparative analysis has shown that the best noise immunity of the systems considered in this paper is the communication system, which uses the time separation of the reference and information signals. During the first half of the bit interval, the switch closes the output of the transmitter directly to the generator of the ultra-wideband signal - forming a reference signal. In the middle of the bit interval, the switch alternates the output to one of two possible positions depending on the encoding signal - "zero" or "one", forming the information part of the ultra-wideband signal. It should also be noted that systems with autocorrelation reception and separate transmission of reference and information signals, provide a high level of structural signal secrecy. Furthermore, they provide the reliable transmission of digital information, especially in interference conditions.

• 정보화정책
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• 제18권3호
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• pp.88-107
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• 2011

본 논문의 목적은 2010년 3월 22일 개정된 전기통신사업법 제32조(이용자보호) 제3항, 제4항, 제5항과 제38조(전기통신서비스 도매제공) 신설 관련 3G(WCDMA) MVNO를 통한 선불요금제 활성화 정책을 제시하는 것이다. 한국은 '11년 6월 현재 선불요금, 상호접속, 사업자선택, 도매제공 그리고 번호이동성 등의 제도개선의 부족으로 인하여 이동전화 선불요금제 가입자가 매우 미미한 수준이다. 그러나 해외 통신서비스 규제기관 및 사업자들은 스마트폰 및 데이터 사용 비중을 높이는 다양한 고객수요를 수용하기 위해 이동전화 선불요금제에 점차 더 많은 정책과 전략을 보이고 있다. 본 논문은 현행 전기통신사업법 하에서 3G MVNO를 통한 선불요금제 활성화를 위해서는 선불데이터시스템과 이동망 분리, 선불요금의 월정액제 하이브리드와 무선망을 통한 휴대폰의 직접충전(Top-up) 시스템 도입, USIM 제도 개선, 이동망 사업자선택제 도입, 선 후불 간 소매가할인 차등, 도매제공의 소매가할인 개정과 의무제공사업자 확대, 그리고 선 후불 간 번호이동성 도입 정책의 심도 있는 검토를 제안하고 있다.

• 융합보안논문지
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• 제22권1호
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• pp.99-111
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• 2022

네트워크 중심전(NCW)으로 전장환경이 변하면서 무기체계는 IT 기술을 융합한 신개념의 무기체계로 진화하고 있고, 이러한 핵심 기능은 대부분 임베디드 소프트웨어로 구현됨에 따라 임베디드 소프트웨어는 무기체계 성능을 좌우하는 핵심 요소로 중요성이 증가하고 있다. IoT 기술이 발전하고 임베디드 소프트웨어의 활용 범위가 확대됨에 따라 점차 고도화되고 다양해지는 사이버 위협은 임베디드 소프트웨어를 운용하는 무기체계로 확대되고 있고, 무기체계는 단일체계로부터 네트워크에 의한 연동까지 다양한 형태로 운영되기 때문에 어플리케이션 수준에서의 보안보다는 시스템 수준인 운영체제 커널 수준에서의 강력한 사이버 보안이 필요한 실정이다. 본 논문에서는 무기체계 임베디드 소프트웨어를 사이버 공격으로부터 보호하기 위하여 운영체제 수준에서 임베디드 소프트웨어를 보호하는 무기체계용 보안 실시간 운영체제의 설계 및 구현과 그 성능 측정 결과에 대하여 설명하였다.