• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1627-1632
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• 2003

The effect of (1) phonon dispersion in thermal conductivity model and (2) the differentiation of group velocity and phase velocity for Ge is examined. The results show drastic change of thermal conductivity regardless of using same relaxation time model. Also the contribution of transverse acoustic (TA) phonon and longitudinal acoustic (LA) phonon is changed by considering more rigorous dispersion model. Holland model underestimates the scattering rate for high frequency TA, so misleading conclusion, i.e. TA is dominant heat transfer mode at high temperature. But the actual reduction of thermal conductivity is much larger than the estimation by Holland model and high frequency TA is no more dominant heat transfer mode. Another heat transfer mechanism may exist for high temperature. Two possible explanations are (1) high frequency LA by Umklapp scattering and (2) optical phonon.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.1
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• pp.209-215
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• 2004

This paper presents the frequency range and an analysis method to find the dominant source of electro-magnetic wave which originates from a spark ignition in engine room. Applying the distributed constant equivalent circuit theory the radiation of probable electro-magnetic wave around an ignition plug and a high voltage cable is studied analytically. Experimental studies are also conducted by measuring the frequency spectrum to obtain the radiating characteristics of electro-magnetic wave. Results from both analytical and experimental studies confirm that an ignition plug and a high voltage cable are dominant sources of electro-magnetic wave and that the radiating frequency is ranged from 1.3[GHz] to 2[GHz] band.

• Journal of Fashion Business
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• v.15 no.3
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• pp.51-66
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• 2011

The purpose of this study is to investigate the effect of the traditional color sentiment on the contemporary clothing color by studying the pictures of street fashion of Dalian in China, in view of the clothing color of women in their 20-30 years of age having highest purchasing power, along with traditional Chinese color. The clothing color is various in frequency depending on the items in street fashion. Due to the seasonal impact of summer, the most frequent item was one-piece dress with the Multi of various color patterns, followed by White, Black, PB, R and B category. In the top color, the White was most prevalent color due to the seasonal factor, followed by Black, Grey, Multi, R, Y, RP category. Achromatic color is more dominant with the ratio of 7:3, comparing with its counterpart, which consists of R and Y category of V, B, P, VP tone. In the bottom color, Dp tone of PB shows most high frequency, followed by Black. This results illustrate that Chinese women prefer blue jeans and to be looked as slimmer by using of the dark colors. In the accessories, colors of bags and shoes show different results. The bag colors show the high frequency of Dk tone, YR category, and the chromatic colors are little bit dominant than achromatic ones with the ratio of 5.3:4.7. On the contrary, the shoes colors show the highest frequency in Black, the achromatic colors are more dominant than chromatic ones with the ratio of 6.6:3.4. These results somewhat diverge from the international color trend. Color trend in Dalian street fashion in which the high frequency of V tone is observed through all the colors of the items followed by P, VP, Lgr tone in sequence. In the light of Chinese traditional color preference, this result denotes that the traditional color preferences of red, yellow are still affecting the contemporary color choices of clothing in Chinese women. The high incidence of PB category in the bottom and one-piece dress does not seem to have its origin form traditional Chinese color sentiment.

• Journal of the Society of Naval Architects of Korea
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• v.50 no.2
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• pp.69-78
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• 2013

This study is constructed to investigate the sloshing effect on the motions of a two-dimensional rectangular cylinder experimentally and numerically. The modes of motion under consideration are sway and roll, and also experimental cases are divided by two categories; 1-DoF roll motion and 2-DoF motion (Coupling sway and roll). It is found that the sway response is considerably affected by the motion of the fluid, particularly near the sloshing natural frequency, while the roll response changes comparatively small. The dominant mode of motion is analyzed for 2-DoF experiments as well. The measured data for 1-DoF motions is compared with numerical results obtained by the Multi-modal approach. The numerical schemes vary in detail with the number of dominant sloshing modes; i.e. there is a single dominant mode for the Single-dominant method, while the Model 2 method assumes that the first two modes are superior. For the roll motion, numerical results obtained by the two different methods are relatively in good agreement with the experiments, and these two results are similar in most wave frequency range. However, the discrepancies are apparent where the fluid motion is not governed by a single mode. But both of numerical methods over-predict the motion at the vicinity of the sloshing natural frequency. In order to correct the discrepancy, the modal damping needs to be investigated more precisely. Furthermore, another multi-modal approach, such as the Boussinesq-type method, seems to be required in the region of the intermediate liquid.

• Journal of Ocean Engineering and Technology
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• v.22 no.3
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• pp.71-75
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• 2008

This paper illustrates haw $Y_2O_3$ contributes to crack-healing strengths as a function of crack-healing temperature and the additive amount. In investigating mechanical properties, the indentation fracture method is very simple and useful, but careful attention must be paid to the statistical data processing because data may be scattered excessively, especially for brittle materials. To estimate accurate AE signal properties we applied the useful time-frequency method with a discrete wavelet analysis algorithm. In experiments, three kinds of specimens were prepared. After the specimens were indented by a Vickers indentor, they were heat-treated and crack-healed to evaluate bending strength and the AE signal. With higher amounts of the additive powder, as 1, 3, or 5% wt. of $Y_2O_3$, the concentrative tendency of dominant frequency trended toward lower frequency groups. The $Al_2O_3$ ceramic with 3% wt. of $Y_2O_3$ was judged most suitable because it demonstrated superior crack-healing ability and relative concentration on the highest frequency group.

• The Korean Journal of Ecology
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• v.20 no.6
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• pp.461-470
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• 1997

There are 7 classes, 17 orders, and 141 species of benthic macroinvertebrates at the 5 study sites from Feb, '91 to May, '92. Total species frequency number has less variations among sites than seasonal changes. Not considering seasonal changes this indicates that there are some influences from outside pollution sources. Seasonally, Ortho chadiinae sp. 2 take 21.2% share of total species. It was the dominant species in Feb. '91. With total average level Ephemeroptera take 51.3% of total species as first dominant species. Diptera 27.8% as second dominant species and Trichoptera 16.7% as third dominant species. Through these biological indexes, they appear to have unstable living environments in summer at sites 1 and 5. One can see that site 1 is more polluted than site 3 because site 1 has more pollution sources such as pastures and recreation areas.

• JSTS:Journal of Semiconductor Technology and Science
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• v.13 no.5
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• pp.482-491
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• 2013

This paper explains modeling and analysis of RC-dominant wires for high-speed wireline transceiver design. A closed form formula derived from telegrapher's equation accurately describes a frequency response of an RC-dominant wire, yet it is simple and intuitive for designers to easily understand design trade-offs without a complex numerical equation solver. This paper explains how the model is derived and how it can help designers in example transceiver designs.

• Explosives and Blasting
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• v.29 no.2
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• pp.51-58
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• 2011

Frequency is a very important factor in discussing the effect on facilities such as precision instruments and therefore, in evaluating the effect of blasting vibration, it is necessary to identity information on frequency in addition to maximum amplitude of vibration. This study collected rock samples in gneiss area to perform an indoor rock test and to identify frequency of blasting vibration according to priming location, performed of single hole test blasting. Then the study decided dominant frequency through FFT and analysed changes according to priming locations. Consequently frequency range according to priming location is indicated top priming is distributed high range, bottom priming is distributed high range, middle priming is distributed evenly range. Frequency trend according to priming location is indicated distance increase with frequency discrease in top priming, distance increase with frequency increase in bottom priming.

• 한국전산유체공학회:학술대회논문집
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• 2006.05a
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• pp.311-314
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• 2006

The supersonic flow around tandem cavities was investigated by three- dimensional numerical simulations using the Reynolds-Averaged Navier-Stokes(RANS) equation with the $\kappa-\omega$ thrbulence model. The flow around a cavity is characterized as unsteady flow because of the formation and dissipation of vortices due to the interaction between the freestream shear layer and cavity internal flow, the generation of shock and expansion waves, and the acoustic effect transmitted from wake flow to upstream. The upwind TVD scheme based on the flux vector split using van Leer's limiter was used as the numerical method. Numerical calculations were performed by the parallel processing with time discretizations carried out by the 4th-order Runge-Kutta method. The aspect ratio of cavities are 3 for the first cavity and 1 for the second cavity. The ratio of cavity interval to depth is 1. The ratio of cavity width to depth is 1 in the case of three dimensional flow. The Mach number and the Reynolds number were 1.5 and $4.5{\times}10^5$, respectively. The characteristics of the dominant frequency between two-dimensional and three-dimensional flows were compared, and the characteristics of the second cavity flow due to the fire cavity flow cavity flow was analyzed. Both two dimensional and three dimensional flow oscillations were in the 'shear layer mode', which is based on the feedback mechanism of Rossiter's formula. However, three dimensional flow was much less turbulent than two dimensional flow, depending on whether it could inflow and outflow laterally. The dominant frequencies of the two dimensional flow and three dimensional flows coincided with Rossiter's 2nd mode frequency. The another dominant frequency of the three dimensional flow corresponded to Rossiter's 1st mode frequency.

• The Journal of Engineering Geology
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• v.8 no.3
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• pp.207-213
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• 1998

A study was conducted to determine the characteristics of acoustic emission(AE) events generated by the expansive cement induced rock fracturing. The dominant frequency and the maximum amplitude of the AE events are changed in relation to the rate of expansive pressure development in the hole. The dominant frequencies are in the range of 150∼230kHz for the small hole tests and 400∼500kHz for the large hole test. The maximum amplitudes are in the range of 0.015∼0.050cm/sec and 0.025∼0.064cm/sec, respectively. The fact that AE events of higher amplitude with higher frequency on the large hole test and lower amplitude with lower frequency on the small hole tests were detected, may strongly imply that the amount of energy consumed for a macro-crack in both tests may be similar. The expansive cement induced crack propagates stably without any distinguished event having higher amplitude and this implies that a macro-crack is a result of stable growth of micro cracks.