• 한국전자거래학회지
• /
• 제25권2호
• /
• pp.1-14
• /
• 2020

ISO 15118은 전기자동차와 전기차 충전기 사이의 통신을 정의하는 국제 표준이다. 또한 충전 서비스를 이용할 때 사용자를 자동인증하는 기술로써 Plug & Charge(PnC)를 정의하였다. PnC는 전기차 사용자 인증, 충전, 요금 청구 등의 모든 과정이 자동으로 처리되는 자동인증기술을 말한다. 표준에 따르면 충전기와 CPS(Certificate Provisioning Service)의 인증서는 V2G(Vehicle to Grid) Root 인증서의 아래에 있어야 한다. 한국의 경우 한국전력공사가 자체적으로 PKI(Public Key Infrastructure)를 운영하고 있으므로 한전이 제공하는 충전기는 V2G Root 인증서의 아래에 있는 것이 어렵다. 따라서 서로 다른 Root 인증서를 가지고 있을 때에도 인증이 가능한 방법이 필요하다. 본 논문에서는 이를 위해 PnC 방식의 인증에 교차 인증서의 적용을 제안한다. 교차 인증서 자동인증은 서로 다른 Root 인증서를 가지더라도 인증이 가능하도록 Root CA의 교차 인증서를 발급하고 인증서 체인에 포함시켜 자동인증을 진행하는 것이다. 교차 인증서 기술을 적용하면 다른 Root 인증서의 아래에 있는 인증서의 검증을 가능하도록 해준다. 본 논문에서는 PnC 방식과 교차 인증서를 적용한 PnC 방식의 자동인증을 구현하여, 두 가지 방식이 모두 사용 가능함을 증명하는 개념 증명을 진행한다. 개발 요구사항과 인증서 프로파일, 사용자 인증 시퀀스를 작성하고, 이에 따라 구현, 실행한다. 이 실험을 통해 두 가지의 자동인증이 실행 가능하고, 특히 교차 인증서를 적용한 PnC 방식의 자동인증의 확장성이 뛰어남을 확인한다.

• 한국재료학회지
• /
• 제21권5호
• /
• pp.263-267
• /
• 2011

The present study was carried out to evaluate the microstructural and mechanical properties of cross-roll rolled pure copper sheets, and the results were compared with those obtained for conventionally rolled sheets. For this work, pure copper (99.99 mass%) sheets with thickness of 5 mm were prepared as the starting material. The sheets were cold rolled to 90% thickness reduction and subsequently annealed at $400^{\circ}C$ for 30 min. Also, to analyze the grain boundary character distributions (GBCDs) on the materials, the electron back-scattered diffraction (EBSD) technique was introduced. The resulting cold-rolled and annealed sheets had considerably finer grains than the initial sheets with an average size of 100 ${\mu}M$. In particular, the average grain size became smaller by cross-roll rolling (6.5 ${\mu}M$) than by conventional rolling (9.8 ${\mu}M$). These grain refinements directly led to enhanced mechanical properties such as Vickers micro-hardness and tensile strength, and thus the values showed greater increases upon cross-roll rolling process than after conventional rolling. Furthermore, the texture development of <112>//ND in the cross-roll rolling processed material provided greater enhancement of mechanical properties relative to the case of the conventional rolling processed material. In the present study, we systematically discuss the enhancement of mechanical properties in terms of grain refinement and texture distribution developed by the different rolling processes.

• 한국항행학회논문지
• /
• 제16권3호
• /
• pp.426-432
• /
• 2012

본 논문에서는 ADSL, VDSL, DVB-C 등의 통신 시스템에 적용되고 있고, 적응변조나 blind equalization에서 유용하게 사용될 수 있는 Cross QAM의 SNR 추정 성능에 대해 분석하였다. 우선 레일리 페이딩 채널에서의 Cross QAM의 심볼에러율을 분석하였다. 그리고, Cross QAM의 성좌점에 대한 판정영역 특성에 착안하여, 성좌 점별로 EVM 기반의 SNR 추정기법을 사용하는 것을 제안하고, 성좌점별로 SNR 추정성능이 다르게 나타남을 시뮬레이션을 통해 확인하였다. 시뮬레이션 결과로부터 Cross QAM에서 SNR 추정에 사용하는 성좌점을 선택적으로 사용하면, AWGN 채널이나 라이시안 페이딩 채널에서 추정성능을 개선할 수 있음을 확인하였다.

• Steel and Composite Structures
• /
• 제35권1호
• /
• pp.29-41
• /
• 2020

Cross-beams of modern through truss bridges are connected to truss chord at its nodes and between them. It results in variable rotational end restraint for cross-beams, thus variable bending moment distribution. This feature is captured in three-dimensional modelling of through truss bridge structure. However, for preliminary design or rapid assessment of service load effects such technique of analysis may not be available. So an analytical method of assessment of rotational end restraint for cross-beam of through truss bridges was worked out. Two cases - nodal cross-beam and inter-nodal cross-beam - were analyzed. Flexural and torsional stiffness of truss members, flexural stiffness of deck members and axial stiffness of wind bracing members in the vicinity of the analyzed cross-beam were taken into account. The provision for reduced stiffness of the X-type wind bracing was made. Finally, general formula for assessment of rotational end restraint was given. Rotational end restraints for cross-beams of three railway through truss bridges were assessed basing on the analytical method and the finite element method (three-dimensional beam-element modelling). Results of both methods show good agreement. The analytical method is able to reflect effects of some structural irregularities. On the basis of the obtained results the general values of rotational end restraint for nodal and inter-nodal cross-beams of railway through truss bridges were suggested.

• Structural Engineering and Mechanics
• /
• 제89권3호
• /
• pp.309-321
• /
• 2024

In this paper, the effect of semi-rigid connections on the stability bearing capacity of cross-bracings in steel tubular transmission towers is investigated. Herein, a prediction method based on the hybrid model which is a combination of particle swarm optimization (PSO) and backpropagation neural network (BPNN) is proposed to accurately predict the stability bearing capacity of cross-bracings with semi-rigid connections and to efficiently conduct its probabilistic assessment. Firstly, the establishment of the finite element (FE) model of cross-bracings with semi-rigid connections is developed on the basis of the development of the mechanical model. Then, a dataset of 7425 samples generated by the FE model is used to train and test the PSO-BPNN model, and the accuracy of the proposed method is evaluated. Finally, the probabilistic assessment for the stability bearing capacity of cross-bracings with semi-rigid connections is conducted based on the proposed method and the Monte Carlo simulation, in which the geometric and material properties including the outer diameter and thickness of cross-sections and the yield strength of steel are considered as random variables. The results indicate that the proposed method based on the PSO-BPNN model has high accuracy in predicting the stability bearing capacity of cross-bracings with semi-rigid connections. Meanwhile, the semi-rigid connections could enhance the stability bearing capacity of cross-bracings and the reliability of cross-bracings would significantly increase after considering semi-rigid connections.

• 공학교육연구
• /
• 제18권5호
• /
• pp.3-10
• /
• 2015

Researchers in science and technology has broadened the scope of research in order to solve complex problems, academic exchange has also been actively carried out. If the paper which is a mean of interdisciplinary approach has a limited term and the formula, it can act as barriers to access for many researchers in various fields. This paper proposes a cross-validation method for eliminating documentary barriers based on discrete event system formalism. We expect that our proposed method will improve a cross-validation considering researchers in another fields.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2004년도 하계종합학술대회 논문집(2)
• /
• pp.517-520
• /
• 2004

Organosilicate films are promising porous low-dielectric materials, which can replace the silicon dioxide films. It was researched that organosilicate films have two different chemical shifts according to the increase of the flow rate ratio. There are the red shift due to the electron deficient substitution group, and the blue shift of the electron rich substitution group. Among these chemical shifts, the blue shift from $1000 cm^{-1}$ to $1250 cm^{-1}$ was related with the formation of pores. The methyl radicals of the electron-rich substitution group terminate easily the Si-O-Si cross-link, and the Si-O-C cage-link near $1057 cm^{-1}$ is originated from the cross-link breakdown due to much methyl radicals.

• Wind and Structures
• /
• 제11권2호
• /
• pp.121-135
• /
• 2008

The paper is concerned with a comparative study of both the along and cross-wind responses of a tall industrial chimney with and without flexibility of soil. The along-wind response has been estimated by means of approaches presented in three Standards: the Polish, the ISO and the Eurocode and by random vibration approach which is outlined below. The cross-wind response has been estimated by means of the three models developed by Vickery and Basu, Ruscheweyh and Flaga and methods presented in Standards: the Polish, the ISO and the Eurocode (Approach 1 and 2). Computer programmes were developed to obtain estimates of responses of a six-flue, 250 m-tall chimney. The analytical results computed according to the methods presented in different standards and random vibration approaches have been compared. Some unexpected conclusions have been observed.

• 한국군사과학기술학회지
• /
• 제9권3호
• /
• pp.109-115
• /
• 2006

The investigation of the polarization cross-coupling in fiber coils was made using white light Michelson interferometer. The white light interferometer has a light source of about 13nm spectral bandwidth and measurement resolution of less than -80dB. The measurement found that the 200m fiber coil has a polarization cross-coupling of about -64dB in average and -46dB in maximum.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2004년도 춘계학술대회 논문집
• /
• pp.400-403
• /
• 2004

A non-heat기leafed steel does not need quenching and tempering processes that are called a heat treatment differently from conventional steel. Since the tensile strength of this steel is higher than 900MPa, a conventional forming process should be changed to incremental forming process such as a cross wedge rolling that requires lower load capacity than conventional ones. In this paper, the cold cross wedge rolling (CWR) die has been designed using CAD/CAE In order to produce near-net-shaped component of ball stud of non-heat-treated cold steel. Finite element analyses were applied in order to investigate process parameters of CWR. Results provide that the stretching angle and the forming angie at knifing zone in CWR process is important parameter to be the stable process under the low friction coefficient condition.