• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.10a
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• pp.57-60
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• 2003

An axisymmetric compressible flow solver accounting for chemical equilibrium has been developed as an analysis tool exclusively suitable for performance prediction and optimum contour design of LRE thrust chamber. By virtue of several features focusing on user-friendliness and effectiveness including automatical grid generation and iterative calculations with changes in design parameters prescribed through only one keyword-type input file, a design engineer can evaluate very fast and easily the influences of various design inputs such as geometrical parameters and operating conditions on propulsive performance. Validations have been carried out for various aspects by detailed comparisons with the result of CEA code, experimental data of JPL nozzle, actual data for two historical engines, and ReTF data for KSR-III.

• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.1047-1051
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• 2004

The design storm is a crucial element in urban drainage design and hydrological modeling. The total rainfall depth of a design storm is usually estimated by hydrological frequency analysis using historic rainfall records. The different geostatistical approaches (ordinary kriging, universal kriging) have been used as estimators and their results are compared and discussed. Variogram parameters, the sill, nugget effect and influence range, are analysis. Kriging method was applied for developing contour maps of design storm depths In bocheong stream basin. Effect to utilize weather radar data and grid-based basin model on the spatial variation characteristics of storm requires further study.

• Textile Coloration and Finishing
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• v.21 no.5
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• pp.41-50
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• 2009

Design of experiments (DoE) concept was successfully applied to determine the optimum processing conditions that yield maximum % exhaustion for berberine interaction with synthetic tanning agent pretreated polyamide substrates. The potential of synthetic tanning agent to provide anionic sites on the polyamide for berberine interaction which is cationic in nature was tested to increase the % exhaustion of berberine in this article. Experiments were designed according to Central Composite Rotatable Design (CCRD). The three factors for synthetic tanning agent pretreatment and two factors for berberine interaction each at five different levels, including central and axial points were considered. Experiments were conducted in a laboratory scale infra-red treatment instrument according to CCRD. For each response, second order polynomial models were developed using multiple linear regression analysis incorporating linear, interactions and squared effects of all variables and then optimized. The significance of the mathematical model developed was ascertained using Excel regression (solver) analysis module. Analysis of variance (ANOVA) was performed to check the adequacy and accuracy of the fitted models. The response surfaces and contour maps showing the interaction of process variables were constructed. Applying Monte Carlo simulation, response surface and contour plots, optimum operating conditions were found and at this optimum point, % exhaustion of 81% and 74% respectively for synthetic tanning agent pretreatment and berberine interaction were observed and subsequently the results were experimentally investigated.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.271-275
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• 2010

Forming tool design is carried out for a manufacturing a outer shell structure of the nozzle extension of regenerative cooling thrust chamber. The method which manufactures outer shell structure of nozzle extension is a metal forming process using thin plate. Because the configuration of outer shell structure is changed after forming process by springback effect, the outer shell structure can't be exactly formed with the same forming tool as configuration of the nozzle extension. Therefore forming tool design considering springback effect is necessary for manufacturing the outer shell structure of the nozzle extension. In this study, new designed forming tool configuration was generated to decrease the errors between nozzle contour and formed structure. The analysis results show that the errors between nozzle contour and formed structure is significantly decreased using the new designed forming tool.

• The Transactions of the Korea Information Processing Society
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• v.4 no.1
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• pp.54-66
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• 1997

Efficient retrieval of image data is an important research issue in multimedia database. This paper proposes a new approach to a content-based image retrieval which allows queries to be composed of the local texture patterns and the slope components of contour points. The texture patterns extracted from the source image using the graylevel co-occurrence matrix and the slope components of contour points extracted from the binary image are converted into a internal feature representation of reduced dimensionality which preserves the perceptual similarity and those features can be used in creating efficient indexing structures for a content-based image retrieval. Experimental results of the image retrievalare presented to illustrate the usefulness of this approach that demonstrates the precision 82%, the recall 87% and the average rang 3.3 in content-based image data retrieval.

• Journal of the Korean Academy of Esthetic Dentistry
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• v.25 no.2
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• pp.79-87
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• 2016

Single visit monolithic restoration can be proceed with digital workflow which consist of intraoral scanning, dental CAD(computer aided design) and restoration milling with CAM(Computer aided manufacturing). While zirconia has more than 900MPa of flexural strength compared with 400MPa for lithium disilicate, shortened fabricating time of lithium disilicate is considered to be a better choice for fabricating single visit full contour monolithic restoration. However, new zirconia materials which are TZI C(Dentsply Sirona) and LUXEN Enamel(Dental Max), new induction heating method of sintering furnace, and new sintering protocols for MoSi2 heating elements sintering furnace offer significantly reduction of full contour monolithic zirconia restoration fabrication time with greater translucency. These new developments lead single visit zirconia restoration in reality.

• Journal of Biomedical Engineering Research
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• v.20 no.4
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• pp.427-433
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• 1999

The purpose of the study is to develop an improved pitch extraction method that can be used in a variety of speech applications such as high-puality compression and vocoding, and recognition and synthesis of speech. To do so, we develop a new electroglottograph (EGG) measurement system that is based on the four modulation-demodulation type spot electrodes for detecting the EGG signals. Then, the glottal closure instant(GCI) is determined from the EGG signals on a real-time basis. We can obtain the pitch contour using the information on the GCI. It turns out that the new pitch contour algorithm (PCA) operates more reliably as compared to the conventional speech-only-based algorithm. In addition, we study the speech source models and glottal vibratory patterns for Koreans by measuring and analyzing the diversified vibration patterns of the vocal from the EGG signals.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.1 s.173
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• pp.79-86
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• 2000

In this study, a method of optimal blank design using the sensitivity analysis has been proposed. To get sensitivity a well-known commercial code PAM-STAMP has been used. In order to verify this method, formings of square cup, clover shaped cup and L shaped cup have been chosen as the examples. With the predicted optimal blank both computer simulation and experiment are performed. Excellent agreements are recognized between the numerical results and the target contour shapes. Through the investigation, the proposed systematic method of optimal blank design is found to be effective in the design of the deep drawing process.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.2
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• pp.9-16
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• 2003

A strategy of the optimal shape design with FEA(Finite Element Analysis) for 2-D structure is proposed by comparing subproblem approximation method with first order approximation method. A cantilever beam with two different loading conditions, a concentrated load and an evenly distribute load, and truss structure with a concentrated loading condition are implemented to optimize the shape. It gives a good design strategy on the optimal truss structure as well as the optimal cantilever beam shape. It is found that the convergence is quickly finished with the iteration number below ten. Optimized shapes of cantilever beam and truss structure are shown with stress contour plot by the results of the subproblem approximation method and the first order approximation methd.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.6
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• pp.421-430
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• 2000

This paper describes an optimal design method which is applied a weighted least square (WLS) method for Magnetic Resonance Imaging (MRI) system. An optimal design approach is presented for a homogeneity superconducting magnet with the superconducting active shield especially for a magnetic resonance imaging system. The WLS is used to obtain the optimal configurations using the least amount and minimum volume of conductor, exhibiting the smallest level of field inhomogeneity and resulting in the least level of stray field. The proposed model is used to design a multiple-shield configuration for a 1.5 T MRI magnet. The field homogeneity is required less than 5 gauss stray field contour within 4m axially and 3m radially from origin. The designed magnet with the actively magnetic shielding coil out of main coils is analyzed by FEM and theoretical analysis method, investigated the field homogeneity.