• 한국수학교육학회지시리즈B:순수및응용수학
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• 제28권4호
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• pp.281-296
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• 2021

In this paper, we suggest a representation for an inverse transform of the generalized Fourier-Feynman transform on the function space C_a,b[0, T]. The function space C_a,b[0, T] is induced by the generalized Brownian motion process with mean function a(t) and variance function b(t). To do this, we study the generalized Fourier-Feynman transform associated with the Gaussian process Ƶ_k of exponential-type functionals. We then establish that a composition of the Ƶ_k-generalized Fourier-Feynman transforms acts like an inverse generalized Fourier-Feynman transform.

• Annals of Clinical Neurophysiology
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• 제13권1호
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• pp.38-43
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• 2011

Background: In the brain, the dominant primary motor cortex (M1) has a greater hand representation area, shows more profuse horizontal connections, and shows a greater reduction in intracortical inhibition after hand exercise than does the non-dominant M1, suggesting a hemispheric asymmetry in M1 plasticity. Methods: We performed a transcranial magnetic stimulation (TMS) study to investigate the hemispheric asymmetry of paired associative stimulation (PAS)-induced M1 plasticity in 9 right-handed volunteers. Motor evoked potentials (MEPs) were measured in the abductor pollicis brevis (APB) muscles of both hands, and MEP recruitment curves were measured at different stimulation intensities, before and after PAS. Results: MEP recruitment curves were significantly enhanced in the dominant, but not the non-dominant M1. Conclusions: These results demonstrate that the dominant M1 has greater PAS-induced plasticity than does the non-dominant M1. This provides neurophysiological evidence for the asymmetrical performance of motor tasks related to handedness.

• Nuclear Engineering and Technology
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• 제41권7호
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• pp.979-988
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• 2009

Tensioned metastable fluids provide a powerful means for low-cost, efficient detection of a wide range of nuclear particles with spectroscopic capabilities. Past work in this field has relied on one-component liquids. Pure liquids may provide very good detection capability in some aspects, such as low thresholds or large radiation interaction cross sections, but it is rare to find a liquid that is a perfect candidate on both counts. It was hypothesized that liquid mixtures could offer optimal benefits and present more options for advancement. However, not much is known about radiation-induced thermal-hydraulics involving destabilization of mixtures of tensioned metastable fluids. This paper presents results of experiments that assess key thermophysical properties of liquid mixtures governing fast neutron radiation-induced cavitation in liquid mixtures. Experiments were conducted by placing liquid mixtures of various proportions in tension metastable states using Purdue's centrifugally-tensioned metastable fluid detector (CTMFD) apparatus. Liquids chosen for this study covered a good representation of both thermal and fast neutron interaction cross sections, a range of cavitation onset thresholds and a range of thermophysical properties. Experiments were devised to measure the effective liquid mixture viscosity and surface tension. Neutron-induced tension metastability thresholds were found to vary non-linearly with mixture concentration; these thresholds varied linearly with surface tension and inversely with mixture vapor pressure (on a semi-log scale), and no visible trend with mixture viscosity nor with latent heat of vaporization.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2003년도 Proceedings of the international symposium on the fusion technology
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• pp.83-87
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• 2003

Experimental blast studies were carried out in a limestone quarry to study the effects of blasting on structures. To have an in-depth understanding of the possible relation between parameters like vibrations, frequency and scale distance and ten trial blast were conducted. 29 monitoring stations were located in such a pattern to give a true representation of blast induced vibrations for the entire mining in this area. The vibrations were monitored in the vicinity of structures surrounding the quarry in the direction towards the village, road, railway line, office building, etc. Scale distances were determined to identify the maximum charge permissible to cause damage to structures.

• Earthquakes and Structures
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• 제3권3_4호
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• pp.341-363
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• 2012

The spectral representation method is a quick and versatile tool for the generation of spatially variable, response-spectrum-compatible simulations to be used in the nonlinear seismic response evaluation of extended structures, such as bridges. However, just as recorded data, these simulated accelerations require processing, but, unlike recorded data, the reasons for their processing are purely numerical. Hence, the criteria for the processing of acceleration simulations need to be tied to the effect of processing on the structural response. This paper presents a framework for processing acceleration simulations that is based on seismological approaches for processing recorded data, but establishes the corner frequency of the high-pass filter by minimizing the effect of processing on the response of the structural system, for the response evaluation of which the ground motions were generated. The proposed two-step criterion selects the filter corner frequency by considering both the dynamic and the pseudo-static response of the systems. First, it ensures that the linear/nonlinear dynamic structural response induced by the processed simulations captures the characteristics of the system's dynamic response caused by the unprocessed simulations, the frequency content of which is fully compatible with the target response spectrum. Second, it examines the adequacy of the selected estimate for the filter corner frequency by evaluating the pseudo-static response of the system subjected to spatially variable excitations. It is noted that the first step of this two-fold criterion suffices for the establishment of the corner frequency for the processing of acceleration time series generated at a single ground-surface location to be used in the seismic response evaluation of, e.g. a building structure. Furthermore, the concept also applies for the processing of acceleration time series generated by means of any approach that does not provide physical considerations for the selection of the corner frequency of the high-pass filter.

• Wind and Structures
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• 제6권6호
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• pp.485-498
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• 2003

This paper presents a mechanical model of Rain-Wind Induced Vibration (RWIV) of stay cables. It is based on the physical interpretation of the phenomenon as given in Cosentino, et al. (2003, referred as Part I). The model takes into account all the main forces acting on cable, on the upper water rivulet (responsible of the excitation) and the cable-rivulet interaction. It is a simplified (cable cross-sectional and deterministic) representation of the actual (stochastic and three-dimensional) phenomenon. The cable is represented by its cross section and it is subjected to mechanical and aerodynamic (considering the rivulet influence) forces. The rivulet is supposed to oscillate along the cable circumference and it is subjected to inertial and gravity forces, pressure gradients and air-water-cable frictions. The model parameters are calibrated by fitting with experimental results. In order to validate the proposed model and its physical basis, different conditions (wind speed and direction, cable frequency, etc.) have been numerically investigated. The results, which are in very good agreement with the RWIV field observations, confirm the validity of the method and its engineering applicability (to evaluate the RWIV sensitivity of new stays or to retrofit the existing ones). Nevertheless, the practical use of the model probably requires a more accurate calibration of some parameters through new and specifically oriented wind tunnel tests.

• Wind and Structures
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• 제38권2호
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• pp.119-128
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• 2024

The aerodynamic damping is an essential factor that can considerably affect the dynamic response of the cable-stayed bridge induced by crosswind load. However, developing an accurate and efficient aerodynamic damping model is crucial for evaluating the crosswind load-induced response on cable-stayed bridges. Therefore, this study proposes a new method for identifying aerodynamic damping of the bridge structures under crosswind load using an extended Kalman filter (EKF) and the particle filter (PF) algorithm. The EKF algorithm is introduced to capture the aerodynamic damping ratio. PF technique is used to select the optimal spectral representation of the noise. The effectiveness and accuracy of the proposed solution were investigated through full-scale vibration measurement data of the crosswind-induced on the bridge's girder. The results show that the proposed solution can generate an efficient and robust estimation. The errors between the target and extracted values are around 0.01mm and 0.003^o, respectively, for the vertical and torsional motion. The relationship between the amplitude and the aerodynamic damping ratio is linear for small reduced wind velocity and nonlinear with the increasing value of the reduced wind velocity. Finally, the results show the influence of the level of noise.

• 만화애니메이션 연구
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• 통권34호
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• pp.81-104
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• 2014

자기반영성은 매체 스스로 자신의 조건과 절차를 텍스트 안에서 검토하며 매체의 본질을 탐구하고자 하는 미학적 전략이다. 이는 외부세계를 투명하게 모사하고자 하였던 재현의 원리가 19세기에 접어들어 위기를 맞이함으로부터 더욱 가속화 되었다. 19세기 초반 사진기술의 발명과 더불어 시작된 급격한 테크놀로지와 생활사회의 변화는 회화가 더 이상 재현의 방법론을 고수할 수 없도록 하였으며, 예술은 격변하는 세계의 페러다임과 맞물리며 새로운 방법론을 취하게 되었다. 이에 시각예술은 자신의 근원적인 매체의 성격을 성찰하고 스스로의 가능성을 재조직하는 자기반영적 전략을 취하게 되었으며 이러한 경향은 모더니즘과 포스트모더니즘에 이어 오늘날에 이르기까지 이어져오고 있다. 본고에서는 관람자로 하여금 애니메이션이 인공적 구성물임을 끊임없이 주지시키며 매체적 특성을 자각하고 인식하도록 유도하는 자기반영적 애니메이션을 중점적으로 다루었다. 첫 번째 장에서는 고대 그리스에서부터 에술의 창작원리로 폭넓게 수용되었던 모방과 미메시스에 기반한 재현 개념의 변화와 이와 관련된 자기반영성의 미학적 방법론을 개괄하였다. 이어 두 번째 장에서는 환영적이며 몰입적 재현에 목적을 두지 않고 애니메이션의 생산과정과 구성요소를 드러내며 자기 인식과 비판을 스스로의 작품 안에서 환기시킴으로써 다른 방식의 영상읽기를 제안하는 텍스트들을 분석하였고, 마지막으로는 애니메이션과 인접한 예술매체들과의 상호매체적인 관계 속에서 애니메이션의 존재론적 정체성과 조건을 탐색하는 상호텍스트적 작품들을 고찰하였다. 급변하는 매체환경 속에서 애니메이션 매체에 관한 재성찰이 요구되는 작금의 시절에, 자기반영성의 전략을 취하며 애니메이션 매체를 스스로 환기시키는 작품을 살펴보는 것은, 애니메이션이 스스로를 어떻게 구성해내고 있으며 무엇을 해나가고 수 있는지에 대한 가능성의 시각을 제공하는데 도움이 되리라 기대한다.

• Wind and Structures
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• 제12권3호
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• pp.239-257
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• 2009

This paper develops and discusses a method by which it is possible to evaluate the Equivalent Static Force (ESF) of wind in the case of long-span bridges. Attention is focused on the alongwind direction. The study herein carried out deals with the classical problems of determining the maximum effects due to the alongwind action and the corresponding ESFs. The mean value of the maximum alongwind displacement of the deck is firstly obtained both by the spectral analysis and the Gust Response Factor (GRF) technique. Successively, in order to derive the other wind-induced effects acting on the deck, the Gust Effect Factor (GEF) technique is extended to long-span bridges. By adopting the GRF technique, it is possible to define the ESF that applied on the structure produces the maximum alongwind displacement. Nevertheless the application of the ESF so obtained does not furnish the correct maximum values of other wind-induced effects acting on the deck such as bending moments or shears. Based on this observation, a new technique is proposed which allows to define an ESF able to simultaneously reproduce the maximum alongwind effects of the bridge deck. The proposed technique is based on the GEF and the POD techniques and represents a valid instrument of research for the understanding of the wind excitation mechanism.

• 대한수학교육학회지:수학교육학연구
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• 제26권1호
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• pp.143-157
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• 2016

본 연구는 초등 예비교사들이 수학적 게임을 변형하는 과정에서 그들이 경험한 수학적 탐구 활동의 사례를 분석하였다. 예비교사들은 기존의 수학적 게임을 변형하거나 새로운 게임을 개발하는 과정에서 수학적 문제 제기, 수학적 추측과 반박, 새로운 수학적 표현 생성 등의 수학적 탐구 활동을 경험할 수 있었다. 또한 이러한 수학적 탐구의 경험은 예비교사들의 수학교육에 대한 관점의 변화를 유도하였다. 본 연구를 통해 수학적 게임 변형 활동이 예비교사에게 수학적 탐구의 기회를 제공하는 수단이 될 수 있음을 확인하였다.