• Journal of Communications and Networks
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• v.12 no.6
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• pp.600-604
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• 2010

A method of width adaptation in the radial basis function network (RBFN) using stochastic gradient (SG) algorithm is introduced. Using Taylor's expansion of error signal and differentiating the error with respect to the step-size, the optimal time-varying step-size of the width in RBFN is derived. The proposed approach to adjusting widths in RBFN achieves superior learning speed and the steady-state mean square error (MSE) performance in nonlinear channel environment. The proposed method has shown enhanced steady-state MSE performance by more than 3 dB in both nonlinear channel environments. The results confirm that controlling over step-size of the width in RBFN by the proposed algorithm can be an effective approach to enhancement of convergence speed and the steady-state value of MSE.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.9
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• pp.2463-2476
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• 1994

Local mean fluctuating velocity components were measured in the separating and reattaching axisymmetrc region of turbulent boundary layer over the wall of convex cylinders placed in a water tunnel by using 2-color 4-beam fiber optics laser Doppler velocimetry. Measurements were made with three different diameters of cylinders with four different diameters of cylinders with four different diameter of the obstructions. The range of Reynolds number based on step height was between 5,000 to 25,200. The study demonstrates that the reattachment length decreases with decreasing cylinder radius and is always shorter than that for the two-dimensional backward-facing step flow at the condition of the same step height. It was also observed that the turbulent kinetic energy in the recirculating region increases with an increases in the radius of convex curvature. The measured velocity field suggests that the transverse curvature can effect definitely the formation of corner eddy.

• Asia pacific journal of information systems
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• v.9 no.2
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• pp.19-37
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• 1999

Computer aided process planning(CAPP) is a key for implementing CIM. It is bridge between CAD and CAM and translates the design information into manufacturing instructions. Generally, manufacturing is an area where intelligent systems will not be able to rely on methods requiring formalized knowledge. Manufacturing lacks a body of knowledge that is specific, formalized, and rigorous, and which can be coded as rules or procedures. Thus expertise in manufacturing is developed over a period of many years. Case-based reasoning(CBR) offers a new approach for developing intelligent system. In the case-based approach the problem solving experience of the experts is encoded in the form of cases. CBR's retrieval process can be divided to two step. The first step is matching step, and the second step is selection step. For selecting base case, new preference heuristics were introduced using similarity concept. Similarity concept has three has three dimensions, i.e. entity similarity, structural similarity, and goal similarity. In this paper, bolt's process planning was selected an application domain. Following the test result, the new preference heuristics were approved as a useful procedure in CAPP.

• Korean Journal of Computational Design and Engineering
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• v.5 no.3
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• pp.232-241
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• 2000

Even though we have greater chances to accomplish successful collaborative design by utilizing recent proliferation of networks, current practices do not fully take advantage of the information infrastructure. There are so much data over the networks, but not enough knowledge about the data is available to users. The main objectives of the product data interface system proposed in this paper are to capture more knowledge on managing product data and to provide users effective search capability. We define the metadata model for product data defined in STEP AP 203 and manage the metadata from product data in a repository system. Because we utilize the standard formats such as STEP for product data and RDF for metadata, the proposed approach can be applied to various fields of industries independently on commercial products.

• Structural Engineering and Mechanics
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• v.23 no.1
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• pp.75-95
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• 2006

Two-step identification approaches for effective bridge health monitoring are proposed to alleviate the issues associated with many unknown parameters faced in real structures and to improve the accuracy in the estimate results. It is suitable for on-line monitoring scheme, since the damage assessment is not always needed to be carried out whereas the alarming for damages is to be continuously monitored. In the first step for screening potentially damaged members, a damage indicator method based on modal strain energy, probabilistic neural networks and the conventional neural networks using grouping technique are utilized and then the conventional neural networks technique is utilized for damage assessment on the screened members in the second step. The effectiveness of the proposed methods is investigated through a field test on the northern-most span of the old Hannam Grand Bridge over the Han River in Seoul, Korea.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.04a
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• pp.284-291
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• 2002

New information technology developments continue to have a significant impact on civil engineering fields. The objective of this study is to develop STEP-based database which will be able to store and manipulate the information of steel bridges over the life cycle. In this study, there are three steps to fulfil the objective to build database and develop the application module for that data model practically and effectively To begin with, STEP methodology for a development of data model has been used for modelling data structure. And then the data model for a steel bridge's shape and structural analysis information has been made up by using AP203 (configuration controlled design) and AP203 (composite and metallic structural analysis and related design) which are the international standard in STEP Lastly, the application module for an access to information of steel bridges has been developed by means of already made database. This study show efficiently the prototype of developing information system with the existing standard technology in civil engineering fields.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.12
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• pp.1810-1814
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• 2017

This paper develops an approach to the algorithm of Gait pattern Analysis and step measurement with Multi-Pressure Sensors. The process of gait consists of 8 steps including stance and swing phase. As 3 parts of foot is supporting most of human weight, multiple pressure sensors are attached on the parts of foot: forefoot, big toe, heel. As 3 parts of foot is supporting most of human weight, multiple pressure sensors are attached on the parts of foot: forefoot, big toe, heel. normal gait proceed from heel, forefoot and big toe over time. While normal gait proceeds, values of heel, forefoot and big toe can be changed over time. So Each values of pressure sensors over time could discriminate whether it is normal or abnormal gait. Measuring Device consists of non-inverting amplifiers and low pass filter. Through timetable of values, normal gait pattern can be analyzed, because of supported weight of foot. Also, the peak value of pressure can judge whether it is walking or running. While people are running, insole of shoes is floating in the air on moment. Using this algorithm, gait analysis and step count can be measured.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.29 no.1
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• pp.33-42
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• 1999

Geometrically standardized dental radiographs were taken. We prepared Digital Cu-Equivalent Image Analyzing System for quantitative assessment of mandible bone. Images of radiographs were digitized by means of Quick scanner and personal Mcquintosh computer. NIH image as software was used for analyzing images. A stepwedge composed of 10 steps of 0.1mm copper foil in thickness was used for reference material. This study evaluated the effects of step numbers of copper wedge adopted for calculating equation. kVp and exposure time on the coefficient of determination(r²)of the equation for conversion to Cu-equivalent image and the coefficient of variation and Cu-Eq value(mm) measured at each copper step and alveolar bone of the mandible. The results were as follows: 1. The coefficients of determination(r²) of 10 conversion equations ranged from 0.9996 to 0.9973(mean=0.9988) under 70kVp and 0.16 sec. exposure. The equation showed the highest r was Y=4.75614612-0.06300524x +0.00032367x² -0.00000060x³. 2. The value of r² became lower when the equation was calculated from the copper stepwedge including 1.0mm step. In case of including 0mm step for calculation. the value of r showed variability. 3. The coefficient of variation showed 0.11, 0.20 respectively at each copper step of 0.2, 0.1mm in thickness. Those of the other steps to 0.9 mm ranged from 0.06 to 0.09 in mean value. 4. The mean Cu-Eq value of alveolar bone was 0.14±0.02mm under optimal exposure. The values were lower than the mean under the exposures over 0.20sec. in 60kVp and over 0.16sec. in 70kVp. 5. Under the exposure condition of 60kVp 0.16sec.. the coefficient of variation showed 0.03. 0.05 respectively at each copper-step of 0.3, 0.2mm in thickness. The value of r² showed over 0.9991 from both 9 and 10 steps of copper. The Cu-Eq value and the coefficient of variation was 0.14±0.01mm and 0.07 at alveolar bone respectively. In summary. A clinical application of this system seemed to be useful for assessment of quantitative assessment of alveolar provided high coefficient of determination is obtained by the modified adoption of copper step numbers and the low coefficient of variation for the range of Cu-Equivalent value of alveolar bone from optimal kVp and exposure time for each x-ray machine.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.506-511
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• 2001

This paper presents how redevelopment of the boundary layer in a backward-facing step flow is affected by boundary conditions imposed on velocity at the inlet, top and exit of the flow. A two-dimensional, laminar, incompressible flow over a backward-facing step with an open top boundary has been computed by using numerical methods of second-order time and spatial accuracy and a fractional-step method that guarantees a divergence-free velocity field at all time. The inlet velocity profile above the step is of Blasius type. Along the top boundary, shear-tree and Dirichlet conditions on the streamwise velocity were considered and at the exit fully-developed and convective boundary conditions were examined. (The vertical velocity at all boundaries were assumed to be zero explicitly or implicitly.) From the computed flow fields, the reattachment on the bottom side of shear layer separated from the tip of the step and succeeding redevelopment of the boundary layer were investigated.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.977-980
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• 1993

The technique to design high performance small motors has been based on experimental data, which results from lots of cost, experience and time in manufacturing. Recently, as high-performance computer appears, many engineers use numerical methods to design and analyze electric machine. Since, the step motor which has very small air gap(0.02-0.05mm) is different from other electric machine in its structure. The shape of rotor teeth and stator teeth influence seriously on the torque characteristics. And it is operated over magnetic saturation point. Therefore, the design of step motor needs to solve nonlinear problem and to calculate magnetic field precisely. In this paper, we solve nonlinear problem by employing Finite Element Method and obtain torque-displacement characteristics for the design of step motor. We also manufacture VR step motor according to the obtained results, and measure some torque characteristics. Through comparing calculated results with experimental results, it is verified that FEM is very useful to design step motor, and the motor designed by our technique is improved in its step accuracy.