• Journal of the Korean GEO-environmental Society
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• v.3 no.1
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• pp.47-55
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• 2002

The slope reinforcing method utilized in this paper reinforces the ground overall by means of filling borehole as well as permeating grout material into ground by injecting it through the grouting pipe. In order to reflect these characteristics to design, not only the ground reinforcing effect by the structural material itself but also the ground strength improvement effect by the grouting injection must be quantitively evaluated. But precedent research of it has been insufficient. Therefore, the slope reinforcing method was applied to the weathered rockmass slope situated in the highway in order to analyze reinforcing effect and the instrumentation of slope was performed. Through analysis of this field test, the slope reinforcing method was proved to be effective and back analysis method based on instrumentation values of slope was proposed to apply to reinforcing design. In this paper, the effectiveness of reinforcing method was certified through proposed back analysis.

• Proceedings of the Acoustical Society of Korea Conference
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• 1991.06a
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• pp.73-77
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• 1991

As the basic analysis to solve the stop consonants in phoneme based speech recognition using Back Propagation learning algorithm, changes in hidden units, training set and iteration. Also we propose an efficient processing method of separation between consonants and vowels.

• The Journal of the Acoustical Society of Korea
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• v.15 no.2
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• pp.72-78
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• 1996

This thesis deals with a method to solve a two-and-one-half-dimensional ($2\frac12$ D) problem, which means that the ocean environment is two-dimensional whereas the source is fully three-dimensionally propagating, including three-dimensional refraction phenomena and three-dimensional back-scattering, using two-dimensional two-way parabolic equation method combined with Fourier synthesis. Two dimensional two-way parabolic equation method uses Galerkin's method for depth and Crank-Nicolson method and alternating direction for range and provides a solution available to range-dependent problem with wave-field back-scattered from discontinuous interface. Since wavenumber, k, is the function of depth and vertical or horizontal range, we can reduce a dimension of three-dimensional Helmholtz equation by Fourier transforming in the range direction. Thus transformed two-dimensional Helmholtz equation is solved through two-way parabolic equation method. Finally, we can have the $2\frac12$ D solution by inverse Fourier transformation of the spectral solution gained from in the last step. Numerical simulation has been carried out for a canonical ocean environment with stair-step bottom in order to test its accuracy using the present analysis. With this spectral parabolic equation method, we have examined three-dimensional acoustic propagation properties in a specified site in the Korean Straits.

• Journal of Korean Tunnelling and Underground Space Association
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• v.22 no.2
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• pp.197-217
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• 2020

Shield TBM tunneling, used in the construction of Seoul subway line 7 and line 9, has been well known as a very efficient, as well as safe, tunneling method. Although the Shield TBM method has been known to be effectively used in poor ground conditions, a number of troubles have occurred during the use of the shield TBM, due to inappropriate machine selection, machine breakdown, and unpredicted ground conditions etc. In this study, several accidents and trouble cases occurred during excavation by Shield TBM, reported from Japan, were investigated. A series of numerical analysis was then performed to compare with the trouble cases and back-analysis results for the cause analysis. The lessons learned from the case studies are presented at the end.

• Journal of the Society of Disaster Information
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• v.15 no.4
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• pp.570-577
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• 2019

Purpose: The purpose of this study is to develop a system that enables quick on-site response using real-time decision-making by sharing the results of measurement and management performed in the field for safe temporary construction. Method: It is possible to take preemptive responses during construction by identifying the safety factors of construction conditions from measurement results and determining the risk factors such as soil properties and variability of climate change that can occur during construction by simultaneously using the back analysis method reflected in the measurement system and structural review. Result: we developed a back analysis algorithm of the SUNEX program to cope with the discrepancies between the design results and measured results due to inconsistency between site conditions and design properties, unexpected loads, and outdoor environment. The process of matching the measurement result with the analysis result can be confirmed in the safety management system. Conclusion: Gateway was used to communicate with real-time measurement results and safety management system program. It was made possible to preemptively respond to risk factors that may occur in the field.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.3 s.357
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• pp.7-17
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• 2007

An analysis and design theory of an aperture-coupled cavity-fed back-to-back microstrip directional coupler is presented for the efficient and optimized design. For this purpose, an equivalent network is developed, and simple but accurate calculations of circuit element values are described. Design equations of the coupler are derived based on the equivalent circuit. In order to determine various structural design parameters, the evolutionary hybrid optimization method based on the genetic algorithm and Nelder-Mead method is invoked. As a validation check of the proposed theory and optimized design method, a 10 dB directional coupler was designed and fabricated. The measured coupling was 10.3 dB at 3 GHz, and the return loss and isolation were 31.8 dB and 30.5 dB, respectively. The directional coupler also showed very good quadrature phase characteristics. Good agreements between the measured and the design specifications fully validate the proposed network analysis and design procedure.

• International Journal of Aeronautical and Space Sciences
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• v.16 no.4
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• pp.510-519
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• 2015

Concerning the issue of high-dimensions, hybrid uncertainties of randomness and intervals including implicit and highly nonlinear limit state function, reliability analysis based on the hybrid uncertainty reliability mode combining with back propagation neural network (HU-BP neural network) is proposed in this paper. Random variables and interval variables are as input layer of the neural network, after the training and approximation of the neural network, the response variables are obtained through the output layer. Reliability index is calculated by solving the optimization model of the most probable point (MPP) searching in the limit state band. Two numerical cases are used to demonstrate the method proposed in this paper, and finally the method is employed to solving an engineering problem of the aerospace friction plate. For this high nonlinear, small failure probability problem with interval variables, this method could achieve a good analysis result.

• Magazine of the Korean Society of Agricultural Engineers
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• v.39 no.6
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• pp.54-66
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• 1997

The objectives of this study is to introduce and apply neural network theory to real hydrologic systems for stochastic nonlinear predicting of daily runoff discharge in the river catchment. Back propagation algorithm of neural network model is applied for the estimation of daily stochastic runoff discharge using historical daily rainfall and observed runoff discharge. For the fitness and efficiency analysis of models, the statistical analysis is carried out between observed discharge and predicted discharge in the chosen runoff periods. As the result of statistical analysis, method 3 which has much processing elements of input layer is more prominent model than other models(method 1, method 2) in this study.Therefore, on the basis of this study, further research activities are needed for the development of neural network algorithm for the flood prediction including real-time forecasting and for the optimal operation system of dams and so forth.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.1
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• pp.42-49
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• 2016

This study was analyed V-bending in order to analyze the spring-back phenomenon in the roll forming process. The material of forming sheet used in the roll forming process is high tension steel and the product name of sheet material is POSTEN 60. The most important variable is the number of roll passes (3-Pass, 4-Pass, 5-Pass, 6-Pass and 10-Pass) and other roll forming process variables were fixed. To determine the characteristics of the tension and compression, the forming sheet was analyzed by dividing the layer (Upper and Bottom) in the thickness direction from the center line. The results of FEM simulation analysis was derived to von-mises stress equivalent strain, and the spring-back value was calculated according to the final forming shape. The more number of the roll pass, von-mises stress and equivalent strain value of forming sheet were lowed. Also, spring-back values tended to decrease. The results of this study can be utilized for prediction and trend of spring-back value in the roll forming process applied to high tension steel sheet. So, development time and cost of the roll forming process is expected to be reduced.

• Journal of Fashion Business
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• v.21 no.1
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• pp.74-87
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• 2017

The aim of this study was to analyze the features of bodice patterns modeled using a dress form that represents Korean female fashion models' body features. A controlled experiment was carried out using an existing dress form that has been frequently used in South Korea. The purpose of the study was to suggest notable findings derived from understanding the development of bodice patterns for Korean female fashion models. The comparison of features of bodice patterns from the developed and existing dress forms was carried out with consideration of the upper body features of the developed dress form, such as body angles and body cross-sectional shapes. The following results were derived from the investigations. (1) The angles of the upper and lower breast cups of the developed dress form differed to those of the existing dress form, showing a 5.0cm smaller front shoulder dart and a 3.5 larger ㎝ ㎝ front waist dart within the bodice patterns. (2) The body angle features of the developed dress form included a straighter neck and shoulder blade and more concave center back than the existing dress form, with a 2.0 reduced back neck height and a 4.8 larger back waist dart for ㎝ ㎝ the bodice back panel. The more realistic body angles of the developed dress form anticipate the improvement of garment pattern-making. (3) The altered shoulder angles resulted in an increased size of the back shoulder dart and a decreased size of the front shoulder height within the bodice patterns. (4) The increased rate of curvature of cross-sectional shapes on the bust and waist circumferences of the developed dress form resulted in an increase in the sizes of the front and back waist darts.