• Journal of Electrical Engineering and Technology
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• v.11 no.1
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• pp.55-64
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• 2016

The development of high-speed rail (HSR) has had a major impact on the power supply grid. Based on the monitored waveforms of HSR, a pattern recognition approach is proposed for the first time in this paper to identify the operating conditions. To reduce the data dimensions for monitored waveforms, the principal component analysis (PCA) algorithm was used to extract the characteristics and their waveforms from the monitored waveforms data. The dynamic time wrapping (DTW) algorithm was then used to identify the operating conditions of the HSR. Cases studies show that the proposed approach is effective and feasible, and that it is possible to identify the real-time operating conditions based on the monitored waveforms.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.05a
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• pp.289-292
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• 2008

Highly over-expanded nozzle of the rocket engines will be excited by non-axial forces due to flow separation at sea level operations. Since rocket engines are designed to produce axial thrust to power the vehicle, non-axial static and/or dynamic forces are not desirable. Several engine failures were attributed to the side loads. Present work investigate the unsteady flow in an over-expanded rocket nozzle in order to estimate side load during a shutdown/starting. Numerical computations has been carried out with density based solver on multi-block structured grid. Present solver is explicit in time and unsteady time step is calculated using dual time step approach. AUSMDV is considered as a numerical scheme for the flux calculations. One equation Spalart-Allmaras turbulence model is selected. Results presented here is for two nozzle pressure ratio i.e. 100 and 20. At 100 NPR, restricted shock separation (RSS) pattern is observed while, 20 NPR shows free shock separation (FSS) pattern. Side load is observed during the transition of separation pattern at different NPR.

• Journal of The Korea Institute of Healthcare Architecture
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• v.10 no.2
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• pp.71-82
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• 2004

The purpose of this study is to analyze the wind velocity ratio in respect of layout types of housing in multi-family housing. The wind velocity ratio is a difference of wind velocity between on the leeward and on the windward side of multi-family housing. The layout types of housing are grid layout pattern of linear type, mixture pattern of Linear type + tower type and layout pattern of tower type. The planning of wind flow is an induced technique to increase in wind velocity in the city and multi-family housing. This study investigates wind velocity ratio into layout types of housing. consequently, analysis were basic design data for the planning techique of wind flow suggested.

• Journal of the Korean Institute of Navigation
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• v.19 no.1
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• pp.9-16
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• 1995

We are confronted with the serious EMI(electromagnetic interference) problems in company with the development of electronic equipments. Accordingly it is also required to construct some anechoic chambers for EMI measurement. Furthermore it is very important to evaluate the chamber characteristics in advance of its construction. For that purpose we have analyzed the characteristics by computer simulation in base on the image method, and compared the results with the measured ones. In case of 3-meter method as a result, the curved line of height pattern of open site varies similarly as that of height pattern of anechoic chamber. When we measure the electromagnetic strength and can get the height pattern curves by frequencies, we utilized it effectively because we can protect instrumental errors in measurement. On the other hand, there is a little difference in site attenuation above 700MHz. When the ferrite grid was used however, the calculated values agree well with the measured values up to 1000MHz with the exception of 30-40 MHz range. The reason is that we don't consider the antenna coupling in the low frequencies of 30-100MHz range.

• Steel and Composite Structures
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• v.24 no.5
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• pp.549-559
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• 2017

As few multi-tower single-box multi-cell cable-stayed bridges with corrugated steel webs have been built, analysis is mostly achieved by combining single-girder model, beam grillage model and solid model in support of the design. However, such analysis methods usually suffer from major limitations in terms of the engineering applications: single-girder model fails to account for spatial effect such as shear lag effect of the box girder and the relevant effective girder width and eccentric load coefficient; owing to the approximation in the principle equivalence, the plane grillage model cannot accurately capture shear stress distribution and local stress state in both top and bottom flange of composite box girder; and solid model is difficult to be practically combined with the overall calculation. The usual effective width method fails to provide a uniform and accurate "effective length" (and the codes fail to provide a unified design approach at those circumstance) considering different shear lag effects resulting from dead load, prestress and cable tension in the construction. Therefore, a novel spatial grid model has been developed to account for shear lag effect. The theoretical principle of the proposed spatial grid model has been elaborated along with the relevant illustrations of modeling parameters of composite box girder with corrugated steel webs. Then typical transverse and longitudinal shear lag coefficient distribution pattern at the side-span and mid-span key cross sections have been analyzed and summarized to provide reference for similar bridges. The effectiveness and accuracy of spatial grid analysis methods has been finally validated through a practical cable-stayed bridge.

• JSTS:Journal of Semiconductor Technology and Science
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• v.4 no.2
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• pp.100-105
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• 2004

The influencing factors on the OPC (optical proximity correction) results are quantitatively analyzed using OPCed L/S patterns. ${\sigma}$ values of proximity variations are measured to be 9.3 nm and 15.2 nm for PR-A and PR-B, respectively. The effect of post exposure bake condition is assessed. 16.2 nm and 13.8 nm of variations are observed. Proximity variations of 11.6 nm and 15.2 nm are measured by changing the illumination condition. In order not to seriously deteriorate the OPC, these factors should be fixed after the OPC rules are extracted. Proximity variations of 11.4, 13.9, and 15.2 nm are observed for the mask mean-to-targets of 0, 2 and 4 nm, respectively. The decrease the OPC grid size from 1 nm to 0.5 nm enhances the correction resolution and the OCV is reduced from 14.6 nm to 11.4 nm. The enhancement amount of proximity variations are 9.2 nm corresponding to 39% improvement. The critical dimension (CD) uniformity improvement for adopting the small grid size is confirmed by measuring the CD uniformity on real SRAM pattern. CD uniformities are measured 9.9 nm and 8.7 nm for grid size of 1 nm and 0.5 nm, respectively. 22% improvement of the CD uniformity is achieved. The decrease of OPC grid size is shown to improve not only the proximity correction, but also the uniformity.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.1
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• pp.72-81
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• 2014

Recently, because of irregular power demand, we have suffered from an electric power shortage. The necessity of the adoption of smart grid which makes effective supply of power by using the two-way communication across the grid between the customers and electric energy providers is growing more and more. If smart grid set up in our country, the third-parties which provide services to customer using the information acquired from smart grid, might be revved up. In this paper, we suggest a methodology how classify the types of family by analysing an power consumption pattern using data mining technique. To make a classifier for categorizing the household types, we need power consumption data and their family type. However, it is hard to get both of them. Therefore we develop the simulator that generates power consumption patterns of the household and classify the types of family. Also, we present a potential for application services such as customized services for a specific family or goods marketing.

• Journal of Coastal Disaster Prevention
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• v.5 no.4
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• pp.183-192
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• 2018

In recent years, coastal areas have been suffering from coastal erosion, such as destruction of coastal roads and military facilities. In this study, the Delft3D model was used to analyze the sediment transport pattern due to seasonal characteristics of summer and winter waves in Anmok beach of the East coast. Typhoon and high waves are mainly are coming from ENE direction in the summer season and the flows occur in the northward. In winter, high waves are incident from NE and the flows occur in the southward. These seasonal patterns were simulated by using Delft3D model. As for model input, reanalysis wave data of the past 38 years were used, and the seasonal patterns were analyzed by dividing the whole year into summer and winter season. The grid point of the 38 year reanalysis data is far from the Anmok beach, so the three model grid systems (wide grid -> intermediate grid -> detailed grid) are constructed. Most of the flows in the NW direction occurred in summer, but erosion and deposition was alternated along the coastline. In winter, sediment was deposited near Gangnung Port due to the southern flow and the southern port. Strong winter waves compared to summer tend to cause deposition around Gangnung Port throughout the year.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.10
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• pp.156-164
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• 1998

Electronic Speckle Pattern Interferometry(ESPI) has been used to measure surface deformations of engineering components and materials in industrial areas. ESPI, a non-contact and non-destructive technique, is capable of providing full-field results with high spatial resolution and high speed. One of the important application using electronic speckle pattern interferometry is electronic speckle contouring of a diffused object for 3-D shape analysis and topography measurement. Generally the electronic speckle contouring is suitable for providing measurement range from millimeters to several centimeters. In this study, we introduce the contouring method by modified dual-beam speckle pattern interferometer and the shift of the two illumination beams through optical fiber in order to obtain the contour fringe patterns. We also describe formation process of depth contour fringes and grid contour fringes by shifting direction of the two illumination beams. Before the experiments, we performed the geometric analysis for dual-beam-shifted ESPI contouring, and then, the electronic speckle contouring experiment with various specimens. For quantitative analysis of the contour fringes, we used 4-frame phase shifting method with PZT Finally, good agreement between the geometric analysis and experimetal results is obtained.

• Fashion & Textile Research Journal
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• v.12 no.5
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• pp.633-641
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• 2010

The purpose of this study is to evaluate a new flight suit in bilateral ways; subjectively and objectively in the improvements of comfort and mobility. Seven healthy males at the age of twenties volunteered in this wearing test. They were over 177 cm in height and 92-95 cm in chest circumference, which satisfies the M95 Special' size described in the Korean Military Specifications and Standards. The subjective satisfaction was evaluated according to the criteria of ease of donning and doffing, fitness of wear, mobility, space between cloth and body, convenience in using restroom. Subjective satisfaction evaluation says that the best improvement of movement are neck circumference, chest breadth, armscye circumference, waist back length, crotch length, crotch height and body rise. According to the evaluation, improvements of mobility were conspicuous especially in parts of body like neck, breast, waist, back, and arms. When evaluating objective satisfaction, we measured a angle difference in a prescribed standard-grid on a photograph that picked up while the subject performed each motion in front of 10 cm-interval grid. As a result, the motion that had angle difference above 5 degrees were arm stretching and standing on single leg holding at forward or at his side. Bending necks and waist, crouching also had angle difference of over 5 degrees. The improvements are discussed from the viewpoint that the increased ease in parts of armscye circumference and crotch in new flight suit pattern.