• Structural Engineering and Mechanics
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• 제61권1호
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• pp.105-116
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• 2017

In this paper, the optimal extended homotopy analysis method (OEHAM) is introduced to deal with the damped Duffing resonator driven by a van der Pol oscillator, which can be described as a complex Multi-Degree-of-Freedom (MDOF) nonlinear coupling system. Ecumenically, the exact solutions of the MDOF nonlinear coupling systems are difficult to be obtained, thus the development of analytical approximation becomes an effective and meaningful approach to analyze these systems. Compared with traditional perturbation methods, HAM is more valid and available, and has been widely used for nonlinear problems in recent years. Hence, the method will be chosen to study the system in this article. In order to acquire more suitable solutions, we put forward HAM to the OEHAM. For the sake of verifying the accuracy of the above method, a series of comparisons are introduced between the results received by the OEHAM and the numerical integration method. The results in this article demonstrate that the OEHAM is an effective and robust technique for MDOF nonlinear coupling systems. Besides, the presented methods can also be broadly used for various strongly nonlinear MDOF dynamical systems.

• 무역학회지
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• 제47권4호
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• pp.137-159
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• 2022

This study aims to analyze international trade papers published in Korea during the past 2002-2022 years. Through this study, it is possible to understand the main subject and direction of research in Korea's international trade field. As the research mythologies, this study uses the big data analysis such as the text mining and Social Network Analysis such as frequency analysis, several centrality analysis, and topic analysis. After analyzing the empirical results, the frequency of key word is very high in trade, export, tariff, market, industry, and the performance of firm. However, there has been a tendency to include logistics, e-business, value and chain, and innovation over the time. The degree and closeness centrality analyses also show that the higher frequency key words also have been higher in the degree and closeness centrality. In contrast, the order of eigenvector centrality seems to be different from those of the degree and closeness centrality. The ego network shows the density of business, sale, exchange, and integration appears to be high in order unlike the frequency analysis. The topic analysis shows that the export, trade, tariff, logstics, innovation, industry, value, and chain seem to have high the probabilities of included in several topics.

• 전자공학회논문지
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• 제53권7호
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• pp.131-137
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• 2016

본 논문에서는 기존의 2D IC의 성능을 개선하고 3D IC의 집적도와 전기적인 특성을 개선하기 위한 목적으로 연구되고 있는 TSV (Through Silicon Via)의 임피던스를 해석하였다. 향후 Full-chip 3D IC 시스템 설계에서 TSV는 매우 중요한 기술이며, 높은 집적도와 광대역폭 시스템 설계를 위해서 TSV에 대한 전기적인 특성에 관한 연구가 매우 중요하다. 따라서 본 연구에서는 Full-chip 3D IC를 설계하기 위한 목적으로 다중 TSV-to-TSV에서 거리와 주파수에 따른 TSV의 임피던스 영향을 해석하였다. 또한 이 연구 결과는 Full-chip 3D IC를 제조하기 위한 반도체 공정과 설계 툴에 적용할 수 있다.

• 대한기계학회논문집A
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• 제26권3호
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• pp.576-585
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• 2002

A three-dimensional Lagrangian explicit time-integration finite element code for analyzing the dynamic impact phenomena was developed. It uses four node tetrahedral elements. In order to consider the effects of strain rate hardening, strain hardening and thermal softening, which are frequently observed in high-velocity deformation phenomena, Johnson-Cook model is used as constitutive model. For more accurate and robust contact force computation, the defense node contact algorithm was adopted and implemented. In order to evaluate the performance of the newly developed three-dimensional hydrocode NET3D, numerical simulations of the oblique impact of mild steel plate by mild steel sphere were carried out. Ballistic limit about various oblique angle between 0 degree and 80 degree was estimated through a series of simulations with different initial velocities of sphere. Element eroding by equivalent plastic strain was applied to mild steel spheres and targets. Ballistic limits and fracture characteristics obtained from simulation were compared with experimental results conducted by Finnegan et al. From numerical studies, the following conclusions were reached. (1) Simulations could successfully reproduce the key features observed in experiment such as tensile failure termed "disking"at normal impacts and outwards bending of partially formed plus segments termed "hinge-mode"at oblique impacts. (2) Simulation results fur 60 degrees oblique impact at 0.70 km/s and 0.91 km/s were compared with experimental results and Eulerian hydrocode CTH simulation results. The Lagrangian code NET3D is superior to Eulerian code CTH in the computational accuracy. Agreement with the experimentally obtained final deformed cross-sections of the projectile is excellent. (3) Agreement with the experimental ballistic limit data, particularly at the high-obliquity impacts, is reasonably good. (4) The simulation result is not very sensitive to eroding condition but slightly influenced by friction coefficient.

• 한국콘텐츠학회논문지
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• 제16권11호
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• pp.179-187
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• 2016

정부의 규제가 기업의 경영활동에 미치는 영향에 대해서 많은 연구자들이 관심을 가지고 분석을 수행하고 있는데 대체적으로 부정적인 영향을 준다는 결과를 제시하여 왔다. 이에 한동안 규제완화 정책이 시도되었으나 최근에는 규제완화보다는 더 나은 규제(better regulation)가 필요하다는 관점에서 규제가 이루어지고 있다. 특히, 신산업이 등장함에 따라 이 분야의 기업 경영활동에 규제가 어떠한 영향을 미치는지를 확인할 필요가 있으며, 이를 바탕으로 신산업 분야의 경영활동에 긍정적인 영향을 주기 위한 규제개선 방향을 수립하는 것도 필요하다. 본 논문에서는 신산업 분야에서 규제가 기업의 경영활동, 기업성과에 미치는 영향을 분석하고 더 나은 규제정책 수립을 위한 시사점을 도출하였다. 분석 결과에 의하면 기업의 규모와 연구개발 집적도에 따라 규제의 영향은 다르게 나타나, 규제정책 수립 시 기업규모와 연구개발 집적도에 대한 고려가 필요하다고 할 수 있다.

• 한국전산구조공학회논문집
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• 제25권5호
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• pp.413-420
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• 2012

본 논문은 2차원 선형탄성 직접 경계요소법에서 저매개변수 요소를 사용할 때 Kernel의 적분방법에 대하여 논의하였다. 일반적으로 등매개변수 요소의 경우 형상함수로 통칭되는 해의 기저함수와 요소의 적분을 위해 사용되는 사상함수를 동일하게 사용한다. 그러나 본 논문에서는 사상함수의 차수를 낮게 취하여 순수기저절점을 도입하고 그때 직접 경계요소의 Kernel을 적분하기 위한 방법이 모색되었다. 일반적으로 경계요소법의 적분 Kernel의 경우 Log수치적분과 코쉬주치(Cauchy principal value) 등을 통해 해결하는데, 본 논문에서는 대수적 조작을 통해 적분값의 정확도를 높일 수 있도록 새로운 수식을 유도하였다. 본 연구에서 저매개변수 기반의 직접 경계요소에 대한 강건성과 정확도를 검증하기 위해 2차원 타원형 편미분방정식으로 표현되는 평면응력과 평면변형문제에 대해 적용하였다. 적용 예제로는 단순연결영역(simple connected region)의 대표적 문제인 캔틸레버보와 다중연결영역(multiple connected region)의 대표적인 문제인 개구부가 있는 사각평면에 대해 각각 수치해석을 수행한 결과 대폭적인 자유도의 감소에 비해 정확도 측면에는 기존의 방법과 차이가 없음을 볼 수 있었다. 본 논문에서 제시된 방법은 기저함수 고차화 저매개변수 직접 경계요소법(subparametric high order boundary element)과 이에 기초를 둔 저매개변수 고차 이중경계요소법(subparametric high order dual boundary element)의 초석이 될 수 있을 것이다.

• Smart Structures and Systems
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• 제14권6호
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• pp.1151-1172
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• 2014

This paper presents a user programmable computational/control platform developed to conduct real-time hybrid simulation (RTHS). The architecture of this platform is based on the integration of a real-time controller and a field programmable gate array (FPGA).This not only enables the user to apply user-defined control laws to control the experimental substructures, but also provides ample computational resources to run the integration algorithm and analytical substructure state determination in real-time. In this platform the need for SCRAMNet as the communication device between real-time and servo-control workstations has been eliminated which was a critical component in several former RTHS platforms. The accuracy of the servo-hydraulic actuator displacement control, where the control tasks get executed on the FPGA was verified using single-degree-of-freedom (SDOF) and 2 degrees-of-freedom (2DOF) experimental substructures. Finally, the functionality of the proposed system as a robust and reliable RTHS platform for performance evaluation of structural systems was validated by conducting real-time hybrid simulation of a three story nonlinear structure with SDOF and 2DOF experimental substructures. Also, tracking indicators were employed to assess the accuracy of the results.

• 대한감각통합치료학회지
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• 제2권1호
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• pp.33-42
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• 2004

Objective : To evaluate the sensory processing ability in relation to parenting stress and find the sensory modulation areas affecting the parenting stress in disabled children Methods : Parents of 124 children with disabilities between 3 to 7 years receiving occupational therapy in Seoul and Gyeonggi-do made out the questionnaire and in items of questionnaire, Short Sensory Profile and Parenting Stress Index of short form was included. Results : Among general information, parenting stress of parents had significant correlation with the degree of disability and correlation with the lower level 2 of Parenting Stress Index. The more sensory processing disability was increased, the more parenting stress was increased. Parenting stress showed the significant correlation with movement sensitivity area and under-responsiveness/behaivor area seeking specific stimulation among sensory processing areas and had significant correlation with tactile sensitivity and auditory filtering. Sensory processing areas which affect the most the Parenting Stress were movement sensitivity and under-responsiveness/behaivor area seeking the specific behavior among sensory control disabilities. Conclusion : The parenting stress of parents with the disabled children had the correlation with sensory processing ability. The difficulty of sensory processing increased the parenting stress. Hence, in order to improve children's sensory processing ability, the appropriately coping program should be developed and the appropriate intervention for improvement of sensory processing ability of children will be necessary.

• 한국정보시스템학회지:정보시스템연구
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• 제25권3호
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• pp.197-215
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• 2016

Purpose This study aims to investigate the factors that influence decision making in relation to providing personal information on the internet with respect to the integration of the privacy calculus theory and protection motivation theory based on the dual-calculus model proposed by Li(2012). Design/methodology/approach The privacy calculus theory and protection motivation theory have been applied to explain privacy behavior to a certain degree but few studies have been conducted to explain privacy behavior based on the integration of these two theories. Although Li(2012) proposed the dual-calculus model, he only proposed its framework and did not carry out an empirical study. Therefore, this study proposes a research model that integrates these two theories and examines the relationship between the two theories through an empirical study. Findings According to the results of empirical analysis, it was found that all relations have statistically significant explanatory power except the relation between coping appraisal and privacy risk in the risk calculus process. Thus, the results verify that external threat played a decisive role in increasing the risk level of a consumer's privacy. It can be discussed the ways to enhance the privacy behavior of consumer on the internet through these findings.

• International Journal of Quality Innovation
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• 제8권2호
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• pp.69-87
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• 2007

High-tech industries in Taiwan exist in an environment with diverse product requirements and intense cost reduction and information integration stress. They must develop new operational directions to increase industry competitiveness. Therefore, Taiwan's high-tech industries must continue R&D and creativity, establish knowledge sharing mechanisms and improve new product development (NPD) performance. This research analyzed and explored the influences of knowledge management (KM) and knowledge sharing mechanisms introduced by Taiwan's high-tech industries on new product development performance. The relationship between knowledge management capabilities and NPD performance is studied. This research considers the intervening industry and corporate position variables. Taiwan's high-tech industries have gradually entered the era of IT region integration and application with competitive advantage creation based upon core techniques. The in-depth study of knowledge management and knowledge sharing introduced by the high-tech industry revealed double meanings in academic and practical applications. The research results showed the following: (1) the stronger the knowledge management capabilities of Taiwan's high-tech industries, the more significant the NPD performance. (2) The better the knowledge sharing mechanism in Taiwan's high-tech industries, the more significant the NPD performance. (3) Corporate scale is not necessarily the critical factor in NPD success and the influence of corporate scale on NPD performance did not show significant differences. (4) The stronger the degree of leading corporate techniques, the more significant the NPD performance.