• 전자통신동향분석
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• 제33권1호
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• pp.57-67
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• 2018

Modern users are intensifying their use of online services every day. In addition, hackers are attempting to execute advanced attacks to steal personal information protected using existing authentication technologies. However, existing authentication methods require an explicit authentication procedure for the user, and do not conduct identity verification in the middle of the authentication session. In this paper, we introduce an implicit continuous authentication technology to overcome the limitations of existing authentication technology. Implicit continuous authentication is a technique for continuously authenticating users without explicit intervention by utilizing their behavioral and environmental information. This can improve the level of security by verifying the user's identity during the authentication session without the burden of an explicit authentication procedure. In addition, we briefly introduce the definition, key features, applicable algorithms, and recent research trends for various authentication technologies that can be used as an implicit continuous authentication technology.

• Structural Engineering and Mechanics
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• 제48권5호
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• pp.711-736
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• 2013

In this paper new implicit time integration called N-IHOA is presented for dynamic analysis of high damping systems. Here, current displacement and velocity are assumed to be functions of the velocities and accelerations of several previous time steps, respectively. This definition causes that only one set of weighted factors is calculated from the Taylor series expansion which leads to a simple approach and reduce the computational efforts. Moreover a comprehensive study on stability of the proposed method i.e., N-IHOA compared with IHOA integration which is performed based on amplification matrices proves the ability of the N-IHOA in high damping vibrations such as control systems. Also, wide range of numerical examples which contains single/multi degrees of freedom, damped/un-damped, free/forced vibrations from finite element/finite difference demonstrate that the accuracy and efficiency of the proposed time integration is more than the common approaches such as the IHOA, the Wilson-${\theta}$ and the Newmark-${\beta}$.

• 산업경영시스템학회지
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• 제17권32호
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• pp.1-6
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• 1994

Many vehicle routing methods have been suggested, which minimize the routing distances of vehicles to reduce the total transportation cost. In describing a distribution network, we have stated that it is basically a system or a set of locations that, receive or store material plus the routes that connect these locations. Whether the network is spread over some geographic region or is whitin a single facility, the definition remains the same. Implicit in this definition, however, is that both the locations and the transportation between these locations must be considered in any decisions regarding the design of the operation of the overall network. The purpose of this paper is optimal layout using transportation quantity and distance in the total system operation. And we minimize the sum of load-carrier costs and spur costs in this flow network.

• 대한수학교육학회지:학교수학
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• 제7권2호
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• pp.123-137
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• 2005

순열 조합의 문제는 내재된 의미 구조에 의해 선택, 분배, 분할의 세 가지의 유형으로 분류될 수 있다. 본 연구에서는 순열 조합의 연산과 문제 유형의 변인이 문제의 난이도에 미치는 영향을 분석하였다 그리고 문제 이해과정에서의 오류를 순서, 중복, 대상의 구별, 같은 것이 있는 순열, 상자의 구별, 분할의 조건, 기타로 분류하고 이해 단계의 장애를 구체적으로 분석하였다. 연구 결과, 순열 조합 연산과 문제의 유형은 난이도에 유의미한 영향을 미치는 것으로 나타났다. 특히 학생들에게 선택, 분할, 분배 문제간의 변환은 쉽지 않으며 순열 조합의 문제에서 학생들이 겪는 어려움 중 하나는 바로 문제 유형의 차이에서 비롯된다는 것을 알 수 있었다. 또한 현 교과서에서는 선택, 분배, 분할을 고려한 다양한 문제 유형이 부족한 것으로 나타났다. 따라서 순열 조합의 지도에 있어 문제 유형을 활용하여 다양한 의미 구조의 문제를 제시하고, 공식위주가 아닌 문제 상황을 충분히 이해하고 이에 대한 해법을 변형, 확장하는 경험을 강조하는 것이 필요하다고 하겠다.

• 한국HCI학회논문지
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• 제3권1호
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• pp.9-17
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• 2008

사용자 경험(UX)이라는 개념이 기존 사용성 중심의 패러다임에 대한 대안으로서 학계와 업계의 지대한 관심을 받고 있다. 그러나 대다수의 경우 사용자 경험에 대한 명확한 정의를 생략하거나 협소한 유사 개념과 혼용하고 있다. 따라서 본 연구에서는 존 듀이의 실용주의 경험 철학에 기반하여 HCI에서의 사용자 경험을 개념적으로 정의하고 최적 사용자 경험의 요건을 제시하였다. 또한 HCI 환경의 변화로 사용자의 경험이 개인적 수준을 넘어 사회적으로 공유되고 있는데, 기존의 UX 개념으로는 이러한 사용자 경험을 설명하기 어렵다. 따라서 본 연구에서는 사회 심리학의 공유 인지 연구를 바탕으로, 사용자 경험을 넘어선 사용자의 공동 경험 개념을 설명하고 사용자의 공동 경험감(CX)이라는 개념의 정의와 조건을 제시하였다.

• 정보관리학회지
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• 제16권2호
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• pp.165-182
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• 1999

본 논문에서는 최근 들어 많은 연구가 진행되고 있는 지식의 정의 및 지식관리에 대해 살펴보고 지식관리시스템의 단계적 절차를 분석함으로써 효율적인 지식관리 방안을 제시하고 있다. 또한, 본 논문은 효율적인 지식관리를 위해 이용자, 지식관리자, 지식관리 기술전문가가 하나의 파트너쉽을 구축해야 한다고 제시하고 있으며 특히, 지식관리자로써 사서의 역할변화에 대해 기술하고 있다. 이러한 연구는 미래의 기존문서, 웹문서 및 각종 멀티미디어 자료등 비정형정보를 지식시스템으로 축적, 유통시킬 수 있는 지식관리시스템 구현을 기초자료로 활용할 수 있을 것이다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2002년도 추계 학술대회논문집
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• pp.95-102
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• 2002

Studies of the numerical characteristics of implicit upwind schemes, such as upwind ADI, Line Gauss-Seidel(LGS) and Point Gauss-Seidel(LU) algorithms, for preconditioned Navier-Stokes equations ate performed. All the algorithms are expressed in approximate factorization form and Von Neumann stability analysis and convergence studies are made. Preconditioning is applied for efficient convergence at low Mach numbers and low Reynolds numbers. For high aspect ratio computations, the ADI and LGS algorithms show efficient and uniform convergence up to moderate aspect ratio if we adopt viscous preconditioning based on min- CFL/max- VNN time-step definition. The LU algorithm, on the other hand, shows serious deterioration in convergence rate as the grid aspect ratio increases. Computations for practical applications also verify these results.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2003년도 추계 학술대회논문집
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• pp.49-55
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• 2003

A comprehensive study has been made for the investigation of the convergence characteristics of the LU scheme for the Euler equations using von Neumann stability analysis. The stability results indicate that the convergence rate is governed by a specific parameter combination. Based on this insight it is shown that the LU scheme will not suffer convergence deterioration at any grid aspect ration if the local time step is defined using appropriate parameter combination. The numerical results demonstrate that this time step definition gives uniform convergence for grid aspect ratios from one to $1\times10^4$.

• 대한기계학회논문집A
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• 제24권5호
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• pp.1075-1083
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• 2000

The prediction of the inelastic behavior of the structure is an essential part of reliability assessment procedure, because most of the failures are induced by the inelastic deformation, such as creep and plastic deformation. During decades, there has been much progress in understanding of the inelastic behavior of the materials and a lot of inelastic constitutive equations have been developed. These equations consist of the definition of inelastic strain and the evolution of the state variables introduced to quantify the irreversible processes occurred in the material. With respect to the definition of the inelastic strain, the inelastic constitutive models can be categorized into elastoplastic model, unified viscoplastic model and separated viscoplastic model and the different integration methods have been applied to each category. In the present investigation, the generalized integration method applicable for various types of constitutive equations is developed and implemented into ABAQUS by means of UMAT subroutine. The solution of the non-linear system of algebraic equations arising from time discretization with the generalized midpoint rule is determined using line-search technique in combination with Newton method. The strategy to control the time increment for the improvement of the accuracy of the numerical integration is proposed. Several numerical examples are considered to demonstrate the efficiency and applicability of the present method. The prediction of the inelastic behavior of the structure is an essential part of reliability assessment procedure, because most of the failures are induced by the inelastic deformation, such as creep and plastic deformation. During decades, there has been much progress in understanding of the inelastic behavior of the materials and a lot of inelastic constitutive equations have been developed. These equations consist of the definition of inelastic strain and the evolution of the state variables introduced to quantify the irreversible processes occurred in the material. With respect to the definition of the inelastic strain, the inelastic constitutive models can be categorized into elastoplastic model, unified viscoplastic model and separated viscoplastic model and the different integration methods have been applied to each category. In the present investigation, the generalized integration method applicable for various types of constitutive equations is developed and implemented into ABAQUS by means of UMAT subroutine. The solution of the non-linear system of algebraic equations arising from time discretization with the generalized midpoint rule is determined using line-search technique in combination with Newton method. The strategy to control the time increment for the improvement of the accuracy of the numerical integration is proposed. Several numerical examples are considered to demonstrate the efficiency and applicability of the present method.

• 대한기계학회논문집B
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• 제27권8호
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• pp.1122-1133
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• 2003

Numerical characteristics of implicit upwind schemes, such as upwind ADI, line Gauss-Seidel (LGS) and point Gauss-Seidel (LU) algorithms, for Navier-Stokes equations have been investigated. Time-derivative preconditioning method was applied for efficient convergence at low Mach/Reynolds number regime as well as at large grid aspect ratios. All the algorithms were expressed in approximate factorization form and von Neumann stability analysis was performed to identify stability characteristics of the above algorithms in the presence of high grid aspect ratios. Stability analysis showed that for high aspect ratio computations, the ADI and LGS algorithms showed efficient damping effect up to moderate aspect ratio if we adopt viscous preconditioning based on min-CFL/max-VNN time-step definition. The LU algorithm, on the other hand, showed serious deterioration in stability characteristics as the grid aspect ratio increases. Computations for several practical applications also verified these results.