• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.127.1-127.1
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• 2013

Recent experimental evidence that fluorinated graphene creates local magnetic moments around F adatoms has not been supported by semilocal density-functional theory (DFT) calculations where the adsorption of an F adatom induces no magnetic moment in graphene. Here, we show that such an incorrect prediction of the nonmagnetic ground state is due to the self-interaction error inherent in semilocal exchange-correlation functionals. The present hybrid DFT calculation for an F adatom on graphene predicts not only a spin-polarized ground state with a spin moment of ${\sim}1{\mu}_B$, but also a long-range spin polarization caused by the bipartite nature of the graphene lattice as well as the induced spin polarization of the graphene states. The results provide support for the experimental observations of local magnetic moments in fluorinated graphene.

• EDISON SW 활용 경진대회 논문집
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• 제6회(2017년)
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• pp.11-15
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• 2017

We present a study of transition metal compounds using density functional theory (DFT), and density-corrected density functional theory(DC-DFT). By replacing the self-consistent density with that obtained from Hartree-Fock calculation, i.e., HF-DFT, the abnormality driven by self-interaction error is removed in several important cases. We discuss when and how HF-DFT works by examining 3d orbital dimers using approximate functionals and by comparing the results from self-consistent-DFT and HF-DFT with experimental values.

• Asia pacific journal of information systems
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• 제25권1호
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• pp.25-60
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• 2015

Use cases are commonly used to represent customer requirements during systems development. In a large software development environment, finding relevant use cases from a library of past or related projects is a complex, error-prone and expensive task. This study proposes an ontological methodology to support use case retrieval in an interactive manner. The architecture of a prototype system that implements this methodology is presented. To evaluate whether the proposed approach can provide satisfactory results to users, this study develops a research model and hypotheses based on interaction theory. These hypotheses are empirically tested using a laboratory experiment which controls information filtering and perceived interaction. Our study suggests that a system which interacts with a user intelligently reduces cognitive load and increases self-efficacy and satisfaction.

• 디지털융복합연구
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• 제20권2호
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• pp.251-260
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• 2022

기술의 발달과 스마트 스피커 보급의 증가에도, 스마트 스피커의 대화 오류로 사용자 만족도는 하락하고 있다. 이 연구는 스마트 스피커의 대화형 에이전트 맥락에서 '자기발화수정 전략'이 과업 중요도 수준과 대화 오류 여부에 따라 사용자 경험에 미치는 영향을 살펴보았다. 대화 오류에 따라 시나리오를 제작하고 과업 중요도 수준에 따라 집단을 나눠 실험을 진행해 신뢰, 지각된 유용성, 지각된 용이성, 수용의도를 측정하였다. 연구 결과, 에이전트의 자기발화수정 전략은 완전한 수행과 비교해 신뢰와 지각된 용이성에 부적 영향을 주며, 과업 중요도와의 상호작용을 통해 수용의도에 영향을 미치는 것을 발견하였다. 이 연구는 대화형 에이전트 연구에서 미흡했던 자기발화수정 전략의 효과를 실증적으로 알아보았고, 자기발화수정 전략의 수용과 관련된 사용자 경험 요인을 살펴보았다는 점에서 의의를 가진다.

• 한국HCI학회:학술대회논문집
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• 한국HCI학회 2009년도 학술대회
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• pp.384-389
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• 2009

일반적으로 사용자의 동작 정보는 human-computer interaction 에 유용하게 사용되는데, 이때 사용자의 의도 파악은 주로 움직임의 가속도 정보를 통해 분석된다. 그러나 일반적인 사람의 움직임은 등속 운동 및 미미한 가속도를 수반하는 경우가 많아 기존의 접근 방식으로는 사용자의 모든 움직임을 검출하기 어려운 단점이 있으며, 경우에 따라서는 부자연스러운 움직임을 유발시키기도 한다. 본 논문에서는 이러한 문제를 해결하기 위해 자연스러운 interaction 을 위한 새로운 인터페이스 방식을 제안하고 이의 활용방안에 대해 논의한다. 제안된 시스템은 중력을 기구부의 복원력으로 활용하여, 초기화와 같은 가속도계 기반의 IMU 의 공통적인 문제를 해결하고 또한 비교적 간단한 움직임으로도 다양한 신호 패턴을 생성시킬 수 있도록 하는 것에 그 목적을 둔다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 추계학술대회 논문집
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• pp.191-196
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• 2005

In this study, to describe vehicle-track-bridge dynamic interaction phenomena with 1/4 vehicle model, nonlinear Hertzian contact spring and nonlinear contact damper are introduced. In this approach external loads acting on 1/4 vehicle model are self weight of vehicle and geometry information of running surface. The constraint equation on contact surface is implemented by Penalty method. Also, to improve the numerical stability and to maintain accuracy of solution, the artificial damper and the reaction from constraint violation are introduced. A nonlinear time integration method, in this study, Newmark method is adopted for both equations of vehicles and structure. And to reduce the error caused by inadequate time step size, adaptive time-stepping technique is partially introduced. As the nonlinear Hertzian contact spring has no resistance to tensile force, the bouncing phenomena of wheelset can be described. Thus, it is expected that more versatile dynamic interaction phenomena can be described by this approach and it can be applied to various railway dynamic problems.

• EDISON SW 활용 경진대회 논문집
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• 제3회(2014년)
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• pp.115-125
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• 2014

We investigate dissociation of diatomic molecules and anions using density functional theory (DFT) and density-corrected density functional theory (DC-DFT). We scan the potential energy curve of CH, NH and NO neutral molecule and its anion with both DFT and DC-DFT (in form of Hartree-Fock DFT, HF-DFT) using various functionals. Using CCSD(T) results as reference, we perform the error decomposition scheme recently proposed by Kim et al. The results show while most neutrals are $functio{\acute{n}}al$ error $domi{\bar{n}}ating$ normal calculations, $CH^-$ and $NO^-$ anions are density-driven error dominating abnormal calculations. In case of $NH^-$, traditional DFT goes to a wrong dissociation limit indicating abnormality, but both HF-DFT and CCSD(T) results need further investigation due to the kinks on the curve.

• Interaction and multiscale mechanics
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• 제6권2호
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• pp.257-270
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• 2013

The use of lightweight materials has been steadily increasing in the automotive industry, and presents new challenges to material joining. Among many joining processes, self-piercing riveting (SPR) is particularly promising for joining lightweight materials (such as aluminum alloys) and dissimilar materials (such as steel to Al, and metal to polymer). However, to establish a process window for optimal joint performance, it often requires a long trial-and-error testing of the SPR process. This is because current state of the art in numerical analysis still cannot effectively resolve the problems of severe material distortion and separation in the SPR simulation. This paper presents a coupled meshfree/finite element with a moving boundary algorithm to overcome these numerical difficulties. The simulation results are compared with physical measurements to demonstrate the effectiveness of the present method.

• 문화기술의 융합
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• 제8권4호
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• pp.445-455
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• 2022

금융 서비스에서 적극적으로 활용되고 있는 챗봇은 대화 오류와 기계적인 답변으로 사용자 경험을 저해하고 있다. 이 연구는 의인화된 챗봇의 자기노출과 감정표현이 금융 서비스에서 대화 오류 시 사용자 경험에 미치는 효과를 살펴보았다. 일상적인 금융 서비스 문의 상황에서 자기노출 유형(긍정적 vs. 부정적)과 감정표현 수준(높은 수준의 자신감 vs. 낮은 수준의 자신감)별로 시나리오를 구성해 온라인 실험을 진행하였고, 신뢰, 곤혹도, 서비스 회복만족, 지속 사용의도를 측정하였다. 실험 결과, 의인화된 챗봇의 자기노출과 감정표현에서 신뢰, 곤혹도, 서비스 회복만족, 지속 사용의도에 대해 각각 주효과가 나타났고 신뢰와 곤혹도에서 상호작용 효과가 나타났다. 결론적으로 의인화된 챗봇이 긍정적 자기노출과 자신감 있는 감정표현을 할 때 상대적으로 신뢰가 높아지고 곤혹도가 낮아지는 것을 확인하였다.

• 동서간호학연구지
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• 제24권1호
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• pp.44-51
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• 2018

Purpose: The purpose of this study was to examine the actor and partner effects of self efficacy, marital adjustment and family support on Yangseang in infertile couples using the actor-partner interdependence model. Methods: The participants were 108 infertile couples. Data were collected using the Yangsaeng Scale, Infertility Self Efficacy Scale, Revised Dyadic Adjustment Scale, and Perceived Social Support Scale from March to April in 2016. The Actor-Partner Interdependence Model was used to analyze the actor and partner effects of self-efficacy, marital adjustment and family support on Yangsaeng. Results: The fit indices for the model were Comparative Fit Index (CFI) = 0.99, Normed Fit Index (NFI) = 0.99, Tucker-Lewis Index (TLI) = 0.90, and Root Mean Square Error of Approximation (RMSEA) = 0.01, which met the criteria. We found that only self efficacy had an actor effect on Yangsaeng. Marital adjustment and family support of infertile husbands had an actor effect on the Yangsaeng. In addition, marital adjustment showed an interaction effect. Conclusions: The findings of this study indicate that the level of Yangseang in infertile couples was positively associated with the levels of self efficacy and martial adjustment. Partner effects may be hidden due to much stronger actor effects on Yangseang.