• Proceedings of the KSME Conference
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• 2004.11a
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• pp.585-590
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• 2004

Many machine failures are not detected well in advance due to the masking of background noise and attenuation of the source signal through the transmission mediums. Advanced signal processing techniques using adaptive filters and higher order statistics have been attempted to extract the source signal from the measured data at the machine surface. In this paper, blind deconvolution using the eigenvector algorithm (EVA) technique is used to recover a damaged bearing signal using only the measured signal at the machine surface. A damaged bearing signal corrupted by noise with varying signal-to-noise (s/n) was used to determine the effectiveness of the technique in detecting an incipient signal and the optimum choice of filter length. The results show that the technique is effective in detecting the source signal with an s/n ratio as low as 0.21, but requires a relatively large filter length.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.17 no.2
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• pp.85-92
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• 2014

This text was analyzed and investigated the morphological character, production time and germination characteristic of seed that collect in Chungnam, in order to offer the basic informations for slope restoration and revegetation using Indigofera amblyantha of wild shrub. Legume was cylindrical type and length 31.5mm, width 2.5mm, and seed number of per legume was full ripe 5.5, unripe 0.9. Seed was elliptical type and length 2.4mm, width 1.7mm, and weight of 1,000 seeds was 5.9g. Because seed matured within December and next year January, optimum time of seed production was in mid of January. In the treatment $H_2SO_4$ of 15 minutes, seed germination rate was the highest as 91.0%, and seed germination time (days) was the shortest as 6.7 days. Seed germination time by temperature was the shortest from $25^{\circ}C$. Therefore, seed germination of Indigofera amblyantha was very useful in the treatment $H_2SO_4$ of 15 minutes from $25^{\circ}C$ temperature.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.45 no.5
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• pp.56-63
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• 2013

In this study, paper mill applicability of two kinds of cotton pulps which have different initial freeness, fiber length and intrinsic fiber strength were investigated. Basic properties such as CED viscosity, fiber length, and crystallinity of major two kinds of cotton pulps were analyzed, and beatability of cotton pulps and physical properties of handsheet made from two kinds of cotton pulps were compared. Laboratory beating was performed at different refining conditions such as refining loads and freenesses. Relationship between beating degree and physical properties of handsheet were compared to seek optimum condition of refining for different cotton pulps application to paper mill.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1057-1058
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• 2011

This paper deals with finding the optimal ratio of height and length of Single-Sided Linear Induction Motors (SLIM) using Finite Element Method (FEM) for magnetic field analysis coupled with optimal design methodology. For effective analysis, FEM is conducted in time harmonic field which provides steady state performance with the fundamental components of voltage and current. The ratio of height to length providing the required output power is obtained by Response Surface Methodology (RSM) and optimal values are presented by the variation in output power. When output power is small, the ratio is high and as the power increases, the ratio shows a converged value. Considering the general application of linear motors, using a small ratio can be limiting, however, the shape ratio for maximum thrust can be identified.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.4
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• pp.1-10
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• 1992

Since the structural system of a prestressed concrete bridge erected by Incremental Launching Method is varying continuosly during construction, the main girder bears alternating stress resultants different from those under a service load condition. The magnitude of these stress resultants depends on span lengths, nose length and stiffness ratios between girder and nose. A parametric study is performed for various span lengths, nose lengths and stiffness ratios. In order to analyze structural systems varying at every launching step two programs are developed; a pre-processor which automatically produces a data file for each stage and a main-processor which can summarize the results of all stages. From the results, the relationships between optimum nose length and stiffness ratio are proposed for various span lengths.

• Journal of the Korean Society of Clothing and Textiles
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• v.44 no.3
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• pp.452-463
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• 2020

This study analyzed wearing conditions to develop an optimum sports brassiere for women in their 50s. A total of 35.9% of the women exercised three times a week and 51.1% had been exercising for more than 2 years, and 58.5% exercised for 30 minutes to 1 hour each day. Regarding the question of whether women wore a sports brassiere when exercising, 54.8% of the respondents answered 'No'. 73.9% of the respondents found a sports brassiere stuffy. The most important factors in purchasing a sports brassiere were wear comfort and functionality. In particular, more exercise demanded greater functionality. When purchasing a sports brassiere, the price range was the highest for 84.3% of the respondents at less than 50,000 won, and 45.2% preferred achromatic colors. A total of 47.9% preferred the length of the sports brassiere to be about 5 cm from the bust; however, the respondents who exercised more preferred shorter length sports brassiere. A total of 57.6% of the respondents preferred the width of the shoulder strap to be 1-3 cm; however, respondents who exercised more preferred the shoulder strap to be more than 3 cm wide. Most respondents preferred the sports brassiere to have a moderate degree of compression at the front breast area.

• Steel and Composite Structures
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• v.10 no.1
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• pp.69-85
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• 2010

The present paper presents a study on the behavior and design of corrugated web steel beams with and without web openings. In the literature, the web opening problem in steel beams was dealt with mostly for steel beams with plane web plates and research on the effect of an opening on a corrugated web was found out to be very limited. The present study deals mainly with the effect of web openings on the transverse load carrying capacity of steel beams with sinusoidally corrugated webs. A general purpose finite element program (ABAQUS) was used. Simply supported corrugated web beams of 2 m length and with circular web openings at quarter span points were considered. These points are generally considered to be the optimum locations of web openings for steel beams. Various cases were analyzed including the size of the openings and the corrugation density which is a function of the magnitude and length of the sine wave. Models without web holes were also analyzed and compared with other cases which were all together examined in terms of load-deformation characteristics and ultimate web shear resistance.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.445-449
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• 2005

The mixed acoustic-convective mode combustion instability and the possibility of combustion control using a loudspeaker to these instabilities were studied. By changing inlet velocity, combustor length and equivalence ratio, the dynamic pressure signals and the flame structures were simultaneously taken. The results showed that as the combustor length increased and the inlet velocity decreased, the instability frequency decreased and the maximum power spectral densities of the dynamic pressures generally decreased. The instability frequency could be affected by an equivalence ratio over the operating conditions. From the data of close-loop control, as the loudspeaker may work out-of-phase with the natural instability, the optimum time-delay controller was confirmed to be able to reduce the vortex shedding from the mixed acoustic-convective mode combustion instability.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.575-578
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• 2011

The thrust vectoring concept has been used for use in new advanced supersonic aircraft. This study presents the performance characteristics of the thrust vectoring nozzle by visualizing the shock behaviors with Schlieren method. We performed experimental tests to see the geometrical effects of the thrust vector nozzle by changing pitch angle and length of pitch flaps. From this study we could understand the supersonic flow characteristics of the thrust vector nozzle. The total thrust of thrust vector nozzle is diminished by increasing the flap angle. But there is an optimum flap length ratio for attaining the highest thrust level and proper pitch effect.

• Journal of Sericultural and Entomological Science
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• v.31 no.2
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• pp.69-71
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• 1989

Experiments were conducted to investigate the effect of topping from mulberry graftages on the their size. Topping season was examined at 10 days intervals from July 15 to August 5 1986 and 1987 on the paddy and upland, respectively. The results were : 1. Topping increased the passed rate of graftages 3.0-15.9%, compared with the control. 2. Optimum season of topping fell around July 15. 3. Topping showed no difference to branch length, survival rate and shoot length in the next year. 4. There was no difference between paddy and upland nursery garden in the passed rate.