• Smart Structures and Systems
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• 제31권2호
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• pp.113-130
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• 2023

Hybrid simulation (HS) has attracted community attention in recent years as an efficient and effective experimental technique for structural performance evaluation in size-limited laboratories. Traditional hybrid simulations usually take deterministic properties for their numerical substructures therefore could not account for inherent uncertainties within the engineering structures to provide probabilistic performance assessment. Reliable structural performance evaluation, therefore, calls for stochastic hybrid simulation (SHS) to explicitly account for substructure uncertainties. The experimental design of SHS is explored in this study to account for uncertainties within analytical substructures. Both computational simulation and laboratory experiments are conducted to evaluate the pseudo-random Sobol sequence for the experimental design of SHS. Meta-modeling through polynomial chaos expansion (PCE) is established from a computational simulation of a nonlinear single-degree-of-freedom (SDOF) structure to evaluate the influence of nonlinear behavior and ground motions uncertainties. A series of hybrid simulations are further conducted in the laboratory to validate the findings from computational analysis. It is shown that the Sobol sequence provides a good starting point for the experimental design of stochastic hybrid simulation. However, nonlinear structural behavior involving stiffness and strength degradation could significantly increase the number of hybrid simulations to acquire accurate statistical estimation for the structural response of interests. Compared with the statistical moments calculated directly from hybrid simulations in the laboratory, the meta-model through PCE gives more accurate estimation, therefore, providing a more effective way for uncertainty quantification.

• 식물분류학회지
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• 제45권4호
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• pp.362-368
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• 2015

꼬리고사리속의 두 개의 신교잡종과 한 개의 미기록교잡종이 발견되었다. 이들 종들의 형태적 형질에 있어 부모종들의 중간형태를 보였다. 거미사철고사리($A.{\times}uiryeongse$)는 서울 북한산 우이령길에서 발견되었고 거미고사리와 사철고사리의 교잡에 의해 분화되었다. 다른 교잡종, 산꼬리고사리($A.{\times}montanus$)는 경기도 연천군, 성산에서 발견되었고, 거미고사리와 차꼬리고사리가 교잡에 의해 만들어지고 다시 꼬리고사리와의 중복교잡에 의해 형성되었다. 아울러 미기록 교잡종인 거미돌담고사리($A.{\times}kitazawae$)는 대구 도동에서 발견되었고, 거미고사리와 돌담고사리의 교잡에 의해 형성되었다. 이들 교잡종들은 부모종들과 같은 장소에서 자란다. 각 분류군의 형질을 분석해 교잡종임을 입증해 보였으며, 이들에 대한 기재, 도해 및 자생지의 서식 사진을 수록하였다.

• Smart Structures and Systems
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• 제14권6호
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• pp.1247-1267
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• 2014

Real-Time Hybrid Simulation (RTHS) is a novel approach conceived to evaluate dynamic responses of structures with parts of a structure physically tested and the remainder parts numerically modelled. In RTHS, delay estimation is often a precondition of compensation; nonetheless, system delay may vary during testing. Consequently, it is sometimes necessary to measure delay online. Along these lines, this paper proposes an online delay estimation method using least-squares algorithm based on a simplified physical system model, i.e., a pure delay multiplied by a gain reflecting amplitude errors of physical system control. Advantages and disadvantages of different delay estimation methods based on this simplified model are firstly discussed. Subsequently, it introduces the least-squares algorithm in order to render the estimator based on Taylor series more practical yet effective. As a result, relevant parameter choice results to be quite easy. Finally in order to verify performance of the proposed method, numerical simulations and RTHS with a buckling-restrained brace specimen are carried out. Relevant results show that the proposed technique is endowed with good convergence speed and accuracy, even when measurement noises and amplitude errors of actuator control are present.

• Structural Engineering and Mechanics
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• 제90권2호
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• pp.159-175
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• 2024

In order to solve the problem of calculating the reasonable completed bridge state of a self-anchored hybrid cable-stayed suspension bridge (SA-HCSB), this paper proposes an analytical method. This method simplifies the main beam into a continuous beam with multi-point rigid supports and solves the support reaction forces. According to the segmented catenary theory, it simultaneously solves the horizontal forces of the main span main cables and the stay cables and iteratively calculates the equilibrium force system on the main beam in the collaborative system bridge state while completing the shape finding of the main span main cable and stay cables. Then, the horizontal forces of the side span main cables and stay cables are obtained based on the balance of horizontal forces on the bridge towers, and the shape finding of the side spans are completed according to the segmented catenary theory. Next, the difference between the support reaction forces of the continuous beam with multiple rigid supports obtained from the initial and final iterations is used to calculate the load of ballast on the side span main beam. Finally, the axial forces and strains of each segment of the main beam and bridge tower are obtained based on the loads applied by the main cable and stay cables on the main beam and bridge tower, thereby obtaining analytical data for the bridge in the reasonable completed state. In this paper, the rationality and effectiveness of this analytical method are verified through a case study of a SA-HCSB with a main span of 720m in finite element analysis. At the same time, it is also verified that the equilibrium force of the main beam under the reasonably completed bridge state can be obtained through iterative calculation. The analytical algorithm in this paper has clear physical significance, strong applicability, and high accuracy of calculation results, enriching the shape-finding method of this bridge type.

• 반도체디스플레이기술학회지
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• 제16권3호
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• pp.31-35
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• 2017

We have fabricated flexible and stretchable pressure sensors using silver nanowires (AgNWs) and analyzed their electric responses. AgNWs are spray coated directly onto uncured polydimethylsiloxane (PDMS) such that AgNWs penetrate into the uncured PDMS, enhancing the adhesion properties of AgNWs. However, the single-layered AgNW sensor exhibits unstable electric response and low pressure sensitivity. To tackle it, we have coated a conductive polymer, poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) onto the AgNW layer. Such a hybrid bilayer sensor ensures a stable electric response because the over-coating layer of PEDOT:PSS effectively suppresses the protrusion of AgNWs from PDMS during release. To enhance the sensitivity further, we have also fabricated a stacked bilayer AgNW sensor. However, its electric response varies depending sensitively on the initial overlap pressure.

• 한국과학교육학회지
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• 제14권1호
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• pp.24-33
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• 1994

This study is aimed at categorizing the CAl programs through analyzing the 82 science CAl programs developed by KEDI( Korean Educational Development Institutes ) and the 19 science CAl programs developed by the teachers who won the prizes in the first national educational software contest. The findings are as follows. 1) The main types of science CAl programs developed by KEDI are hybrid design type of tutorials and simulations, tutorials, and hybrid design type of instructional games and drill and practice. The other type of programs are very few. 2) The main types of science CAl programs developed by the teachers, who won the prizes in 1st educational software contest, are tutorials and hybrid design type of tutorials and simulations. There is no other type of programs except only two simulation type programs. 3) The science CAl programs developed by KEDI as well as by teachers who won the prizes in the contest are biased in two or three types, and the trend is severe in the programs developed by the teachers.

• Journal of Information Processing Systems
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• 제20권1호
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• pp.105-115
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• 2024

The hybrid teaching approach of "MOOC + SPOC + Flipped Classroom" overcomes the constraints of time and space that are typically associated with traditional teaching methods, thus compensating for the shortcomings of traditional approaches. These changes in education are driven by the "Internet+" wave and the growing popularity of online teaching. The "MOOC + SPOC + Flipped Classroom" hybrid teaching mode can successfully compensate for the drawbacks of traditional teaching methods, thereby overcoming their restrictions. By defining relevant concepts, one can distill the key characteristics of the "MOOC + SPOC + Flipped Classroom" hybrid teaching mode. Formative assessment was employed to thoroughly evaluate the effectiveness of this teaching approach. By leveraging the advantages of massive open online course (MOOC), small private online course (SPOC), and flipped classroom, the "MOOC +SPOC + Flipped Classroom" teaching mode incorporates real-time student assessment through peer evaluation, computer-aided evaluation, and teacher evaluation. This mode promotes the simultaneous development of theoretical knowledge and practical skills, helping students to establish strong foundations while fostering their practical abilities. While the traditional teaching method remains fruitful, the convenience of today's network allows the teaching profession to continually evolve. The traditional teaching mode heavily relies on teachers, making it impossible to conduct lessons without them. However, the development of MOOC enables students to seek knowledge online from their preferred teachers, rather than solely relying on their assigned instructors.

• 공학교육연구
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• 제13권6호
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• pp.132-142
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• 2010

본 연구에서는 공학인증에서 필수적인 학습성과 평가항목 중 복합학제적 능력평가(학습성과 6)와 의사소통능력(학습성과 7)에 대한 평가방법을 제시하고자 한다. 본 논문에서는 주관적 관점의 팀워크와 의사소통능력을 객관적으로 계량화하기 위해 팀워크와 의사소통능력에 대한 채점기준(Rubric)을 활용하여 평가 기준을 제시한다. 학습성과 6,7번 항목에 해당하는 팀워크와 의사소통능력은 현대 사회의 중요한 사회적 역량으로 사회 및 교육 분야에서 이루어진 많은 연구들은 팀워크와 의사소통능력을 학습을 통해 신장시킬 수 있으므로 사회학적, 교육학적 관점이 함께 논의되어야 한다. 그러나 이 점을 다룬 논문이 매우 드물기 때문에 본 논문에서는 공학인증에서 필수적인 학습성과 6, 7번 항목에 대한 좀 더 타당한 평가 기준을 제시하기 위해 사회 및 교육학적 관점을 함께 제시하고자 하며 예시와 관련교과목을 제시하고자 한다.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제21권3호
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• pp.165-181
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• 2014

We establish a common n-tupled fixed point theorem for hybrid pair of mappings under new contractive condition. It is to be noted that to find n-tupled coincidence point, we do not use the condition of continuity of any mapping involved. An example supporting to our result has also been cited. We improve, extend and generalize several known results.

• Nonlinear Functional Analysis and Applications
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• 제27권4호
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• pp.731-742
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• 2022

In this paper, we present a new mixed type iterative process for approximating the common fixed points of single-valued nonexpansive mapping and multi-valued nonexpansive mapping in a CAT(0) space. We demonstrate strong and weak convergence theorems for the new iterative process in CAT(0) spaces, as well as numerical results to support our theorem.