• Wind and Structures
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• v.30 no.5
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• pp.499-509
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• 2020

The aeroelastic stability of a long-span suspension footbridge with a bluff deck (prototype section) was examined through static and dynamic wind tunnel tests using a 1:10 scale sectional model of the main girder, and the corresponding aerodynamic countermeasures were proposed in order to improve the stability. First, dynamic tests of the prototype sectional model in vertical and torsional motions were carried out at three attack angles (α = 3°, 0°, -3°). The results show that the galloping instability of the sectional model occurs at α = 3° and 0°, an observation that has never been made before. Then, the various aerodynamic countermeasures were examined through the dynamic model tests. It was found that the openings set on the vertical web of the prototype section (web-opening section) mitigate the galloping completely for all three attack angles. Finally, static tests of both the prototype and web-opening sectional models were performed to obtain the aerodynamic coefficients, which were further used to investigate the galloping mechanism by applying the Den Hartog criterion. The total damping of the prototype and web-opening models were obtained with consideration of the structural and aerodynamic damping. The total damping of the prototype model was negative for α = 0° to 7°, with the minimum value being -1.07%, suggesting the occurrence of galloping, while that of the web-opening model was positive for all investigated attack angles of α = -12° to 12°.

• Geophysics and Geophysical Exploration
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• v.5 no.2
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• pp.93-98
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• 2002

A three dimensional model for the orebody of an operating mine in Korea was constructed by using a program called '3-D Modeler'. The program allows the user to interactively construct a 3-D model of an orebody from its horizontal cross-sections. The 3-D Modeler is easily able to combine and display various spatial data for model construction. The result of modeling is strongly influenced by control points that correlate to the adjacent horizontal cross-sections. The control points are determined by comparing the geometrical shape of the adjacent cross-sections in conjunction with the geological features of the orebody. The resulting model can be evaluated in viewing the constructed object in three dimensional space or more closely evaluated by inspecting the cross-section. The model can iteratively be improved by modifying the shape of the cross-section and by using this new cross-section for the model building.

• Women's Health Nursing
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• v.17 no.2
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• pp.109-117
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• 2011

Purpose: This study examined the impact factors of cesarean section based on the ecological approach in Korea. Methods: Population-based data (Korea Institute for Health and Social Affairs) were used from 2,849 delivery cases during 2003~2009. Data were analyzed using geographic statistics with STATA 10.0 and hierarchical logistic regression with SPSS/WIN 12.0. Results: The range of cesarean section rate was 28.8~44.7% with geographic distribution. The proportion of mother's problem was increasing in choice of cesarean section. According to the ecological model, age of mother (OR=1.08), time of birth (OR=0.79), delivery in hospital (OR=1.83), delivery in clinic (OR=1.46), and education of mother (OR=2.61) had significant impact on cesarean section. Conclusion: This study contributes to provide the impact factors of the high cesarean rate in Korea ecologically. Policy maker and health care provider can consider these results to reduce cesarean section rate.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.6
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• pp.276-284
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• 1998

Optimum design of bumper beam is investigated using nonlinear CAE structural analysis techniques.In order to minimize its weight, while enhancing structural performances, bumper beam structural analyses were carried out to produce optimum section. Model is composed of bumper beam and stay. First, considering FMVSS safety standard, static strength and energy absorbing capability were estimated for several competitive bumpers through pendulum static analysis, and most promising section was chosen. Next, to ensure dynamic crashworthinesss performance for center pole impact was evaluated for the bumper beam with chosen section through pendulum static analysis, referring to DHS bumper dynamic impact standard. Finally, 2.5 mph bumper beam was designed and its structural performance was estimated. Through this investigation, an optimized bumper beam section with less weight of 20% while maintaining almost equal carshworthiness, compared with a conventional bumper beam section which proved its impact crashworthiness by experiments, was developed.

• International Journal of Control, Automation, and Systems
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• v.4 no.2
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• pp.139-145
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• 2006

A multi-variable Golden-Section adaptive controller is proposed for the tracking control of robotic manipulators with unknown dynamics. With a small sample time, the unknown dynamics of the robotic manipulator are denoted equivalently by a characteristic model of a 2-order multivariable time-varying difference equation. The coefficients of the characteristic model change slowly with time and some of their valuable characteristic relationships emerge. Based on the characteristic model, an adaptive algorithm with a simple form for the control of robotic manipulators is presented, which combines the multi-variable Golden-Section adaptive control law with the weighted least squares estimation method. Moreover, a compensation neural network law is incorporated into the designed controller to reduce the influence of the coefficients estimation error on the control performance. The results of the simulations indicate that the developed control scheme is effective in robotic manipulator control.

• Computers and Concrete
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• v.15 no.6
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• pp.865-878
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• 2015

In order to construct a multiscale model for the compressive strength of plain concrete columns with circular cross section subjected to central longitudinal compressive load, a column failure mechanism is proposed based on the theory of internal instability. Based on an energy analysis, the multiscale model is developed to describe the failure process and predict the column's compressive strength. Comparisons of the predicted results with experimental data show that the proposed multiscale model can accurately represent both the compressive strength of the concrete columns with circular cross section, and the effect of column size on its strength.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2004.04a
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• pp.127-139
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• 2004

The process of papermaking involves water removal on the paper machine wire, in the press section and in the dryer section. In the dryer section, liquid water in the wet web is removed mainly by evaporation. In conventional machine this is achieved by passing the web over a number of steam heated dryer rolls. A drying process of paper on a heated cylinder roll calculated based on a 1-dimensional model which concerns unsteady heat and mass transfer in the direction of paper thickness. In this study, Prediction of moisture contents average paper sheet temperature and volume fraction along a series of cylinder. Independently, developed models is compared using the same reference data. The model is implemented in CFD code, FLUENT, using user-define-function(UDFs).

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.426-429
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• 2001

Many various products are manufactured which have sculptured surfaces recently. Constructing surface of these models is required technique called reverse engineering. In reverse engineering, a product which has sculptured surfaces is measured and we create surface model to acquire complete model data of object. Measured point data needs preprocess and sampling. Next a set of point data in a plane fit section curve. At last, surface is generated by fitting to section curves. Here we uses sweep surface. Sweep surface is compatible fitting CAD model to drawing. This paper discusses converting approximation of NURBS surface as a standard surface.

• International Journal of Advanced Culture Technology
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• v.8 no.2
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• pp.159-164
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• 2020

The response analysis of frame structure with open section beams considering warping conditions and short duration load have been performed. When a beam of frame structure is subjected under torsional moment, the cross section will deform a warping as well as twist. For some thin-walled sections warping will be large, and accompanying warping restraint will induce axial and shear stresses and reduce the twist of beam which stiffens the beam in torsion. Because of impact or blast loads, the wave propagation effects become increasingly important as load duration decreases. This paper presents that a warping restraint in finite element model effects the behavior of beam deformation, dynamic mode shape and response analysis. The computer modelling of frame is discussed in linear beam element model and linear thin shell element model, also presents a correlation between computer predicted and actual experimental results for static deflection, natural frequencies and mode shapes of frame. A method to estimate the number of normal modes that are important is discussed.

• ETRI Journal
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• v.46 no.1
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• pp.96-105
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• 2024

We propose a method to automatically predict Alzheimer's disease from speech data using the ChatGPT large language model. Alzheimer's disease patients often exhibit distinctive characteristics when describing images, such as difficulties in recalling words, grammar errors, repetitive language, and incoherent narratives. For prediction, we initially employ a speech recognition system to transcribe participants' speech into text. We then gather opinions by inputting the transcribed text into ChatGPT as well as a prompt designed to solicit fluency evaluations. Subsequently, we extract embeddings from the speech, text, and opinions by the pretrained models. Finally, we use a classifier consisting of transformer blocks and linear layers to identify participants with this type of dementia. Experiments are conducted using the extensively used ADReSSo dataset. The results yield a maximum accuracy of 87.3% when speech, text, and opinions are used in conjunction. This finding suggests the potential of leveraging evaluation feedback from language models to address challenges in Alzheimer's disease recognition.