• Speech Sciences
• /
• v.2
• /
• pp.125-134
• /
• 1997

Human beings can perceive various aspects of sound including loudness, pitch, length, and timber. Recently many studies were conducted to clarify complex auditory scales of the human ear. This study critically reviews some of these scales (decibel, sone, phon for loudness perception; mel and bark for pitch) and proposes to apply the scales to normalize acoustic correlates of human speech. One of the most important aspects of human auditory perception is the nonlinearity which should be incorporated into the linear speech analysis and synthesis system. Further studies using more sophisticated equipment are desirable to refine these scales, through the analysis of human auditory perception of complex tones or speech. This will lead scientists to develop better speech recognition and synthesis devices.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2003.11a
• /
• pp.176-176
• /
• 2003

The effects of oxide thickness and gate length of MgO/GaN metal oxide semiconductor field effect transistors (MOSFETs) on I-V, threshold voltage and breakdown voltage characteristics were examined using a drift-diffusion model. The saturation drain current scales in an inverse logarithmic fashion with MgO thickness and is < 10$^{-3}$ A.${\mu}{\textrm}{m}$$^{-1}$ for 0.5 ${\mu}{\textrm}{m}$ gate length devices with oxide thickness > 600 $\AA$ or for all 1 ${\mu}{\textrm}{m}$ gate length MOSFETs with oxide thickness in the range of >200 $\AA$. Gate breakdown voltage is > 100 V for gate length >0.5 ${\mu}{\textrm}{m}$ and MgO thickness > 600 $\AA$. The threshold voltage scales linearly with oxide thickness and is < 2 V for oxide thickness < 800 $\AA$ and gate lengths < 0.6 ${\mu}{\textrm}{m}$. The GaN MOSFET shows excellent potential for elevated temperature, high speed applications.

• Smart Structures and Systems
• /
• v.22 no.1
• /
• pp.27-40
• /
• 2018

The governing equations of motion are derived for analysis of a sandwich microbeam in this paper. The sandwich microbeam is including an elastic micro-core and two piezoelectric micro-face-sheets. The microbeam is subjected to transverse loads and two-dimensional electric potential. Higher-order sinusoidal shear deformation beam theory is used for description of displacement field. To account size dependency in governing equations of motion, strain gradient theory is used to mention higher-order stress and strains. An analytical approach for simply-supported sandwich microbeam with short-circuited electric potential is proposed. The numerical results indicate that various types of parameters such as foundation and material length scales have significant effects on the free vibration responses and dynamic results. Investigation on the influence of material length scales indicates that increase of both dimensionless material length scale parameters leads to significant changes of vibration and dynamic responses of microbeam.

• Proceedings of the Korea Crystallographic Association Conference
• /
• 2003.05a
• /
• pp.7-7
• /
• 2003

Heteromagnetic nanostructures, which consist of two or more different layers such as nonmagnet, insulator, ferromagnet, antiferromagnet, and superconductor, have been widely used in current and likely future spintronics devices. Their many intriguing magnetic properties are originated from a variety of magnetic interactions at relevant length scales at or near interfaces and between different constituent layers as well as laterally different regions in chemical and magnetic heterogeneity. The fundamental properties can thus differ along depth and laterally in the film plane, depending on their relevant coupling length scales. The entire properties may be characterized by interface properties and/or the depth-varying properties of the individual constituent layers, and lateral inhomogeneity as well. It is a challenge to investigate both depth-varying properties and lateral heterogeneity in such heteromagnetic nanostructures. In this talk, soft x-ray magneto-optical effect as a nanometer scale probe of a variety of heteromagnetic structures is presented and its related noble techniques are introduced. For instances, magnetization vector imaging to investigate vector spin configurations in the film plane is presented, as well as the Kerr rotation, ellipticity, and intensity measurements as a depth sensitive probe on the atomic scales.

• Proceedings of the KSME Conference
• /
• 2001.11b
• /
• pp.9-13
• /
• 2001

In the present study, the friction coefficients (Fanning and Moody coefficients) and the Nusselt number is reviewed from an educational point of view. It is discussed that these dimensionless numbers can be treated with two lengh scales. Also, the similarity between the momentum and heat transfer is discussed based on the length scales.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.33 no.8
• /
• pp.733-738
• /
• 2009

Mechanical properties of <001> silicon nanowires are presented. In particular, predictions from the calculations based on different length scales, first principles calculations, atomistic calculations, and continuum nanomechanical theory, are compared for <001> silicon nanowires. There are several elements that determine the mechanics of silicon nanowires, and the complicated balance between these elements is studied. Specifically, the role of the increasing surface effects and reduced dimensionality predicted from theories of different length scales are compared. As a prototype, a Tersoff-based empirical potential has been used to study the mechanical properties of silicon nanowires including the Young's modulus. The results significantly deviates from the first principles predictions as the size of wire is decreased.

• 한국연소학회:학술대회논문집
• /
• 2006.04a
• /
• pp.128-134
• /
• 2006

A characterization of turbulent reacting flows has proved difficult owing to the complex interaction between turbulence, mixing, and combustion chemistry. There are many types of time scales in turbulent flame which can determine flame structure. This counter jet type premixed burner produces high intensity turbulence. The goal is to gain better insights into the flame structures at high turbulence. 6 propane/air flames gave been studied with high velocity fluctuation in bundle type nozzle and in one hole type nozzle. By measuring velocity fluctuation, turbulent intensity and integral length scale are obtained. And sets of OH LIF images were processed to see flame structure of the mean flame curvatures and flame lengths for comparison with turbulence intensity and turbulent length scales. The results show that the decrease in nozzle size generates smaller flow eddy and mean curvatures of the flame fronts, and a decrease in Damkohler number estimated from flow time scale measurement.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.11 no.1
• /
• pp.1-9
• /
• 1999

For roughened annular pipes with diameter ratios of 0.26, 0.39, and 0.56 and with Reynolds numbers ranging 13,000 to 67,000, friction factor, autocorrelation coefficients, power spectral density functions, and integral length scales for each flow condition using X-type hot wire anemometry system are experimentally investigated. Distributions of these quantities show that the times which the streamwise autocorrelation coefficients become zero first increase with decreasing the radius ratios of concentric annuli and Reynolds numbers, however the power spectra density functions increase with increasing the radius ratios and Reynolds number.

• Korean Journal of Child Studies
• /
• v.4
• /
• pp.37-51
• /
• 1983

The purpose of this study was the investigation of theoretical and empirical relationships between Piagetian and psychometric assessments of intelligence. Specifically, the factor structure of Piagetian-type scales, the relationship between Piagetian scales and psychometric intelligence tests, and differences in the factor structure of Piagetian and psychometric assessments of intelligence were studied. The subjects of this stuby were 70 children (35 boys and 35 girls) in the 1st grade of an elementary school in Seoul The Piagetian-type scales and the K-WISC were administered individually, and the General Intelligence Test was administered to groups of children. Statistical analysis of the obtained data consisted of the SPSS Computer program including factor analysis and Pearson's product moment correlation coefficient. The Piagetian-type scales were found to consist of three factors, which accounted for 55 percent of the total common-factor variance. Factor-I was a factor indicating "conservation". Factor-II was a factor indicating "moral judgements". Factor-III was a factor indicating "classification and identity". Correlations between subtests of psychometric tests and Piagetian scales were relatively low or moderate. Relations between IQs assessed by the psychometric tests and Piagetian scales were also relativeyly low or moderate. Eight factors were extracted from the joint factor analysis of psychometric intelligence tests and Piagetian scales, and they accounted for 67 percent of the total common-factor variance. Factors-I, II, III, and V consisted of subtests of psychometric assessments, and Factors-IV, VI, VII and VIII were composed of Piagetian scales. Factor-I was a factor for "reasoning ability based upon language". Factor-II was a factor for "performance ability". Factor-III was a factor for "grouping ability". Factor-IV was a factor for "conservation". Factor-V was a factor indicating "symbol and language usage ability". Factor- VI was a factor indicating "moral judgments". Factor-VII was a factor indicating "length consevation". Factor-VIII was a factor indicating "classification and identity".

• Fisheries and Aquatic Sciences
• /
• v.19 no.10
• /
• pp.43.1-43.5
• /
• 2016

Three specimens of Lutjanus ophuysenii (217.8-226.7 mm in standard length) were collected by a gill net at Korea between August 2015 and July 2016. This species has not previously been recorded from Korea. L. ophuysenii is very similar to Lutjanus vitta. But several morphological characteristics distinguish the two species, including the number of lateral line scales (46-49 scales in L. ophuysenii; 49-52 scales in L. vitta), a black spot in the middle part of the longitudinal stripe (present in L. ophuysenii; absent in L. vitta), and the absence of a scale on posterior end of the preopercle in L. ophuysenii (present in L. vitta). The Korean name proposed for L. ophuysenii is "Jeom-jul-tung-dom."