• 천문학회지
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• 제44권1호
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• pp.1-11
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• 2011

A sample of 145 JHK-2MASS observations of NGC open star clusters is studied, of which 132 have never been studied before. Twelve are classified as non-open clusters and 13 are re-estimated self-consistently, after applying the same methods in order to compare and calibrate our reduction procedures. The fundamental and structural parameters of the 120 new open clusters studied here are derived using color-magnitude diagrams of JHK Near-IR photometry with the fitting of solar metallicity isochrones. We provide here, for the first time, a catalog of the main parameters for these 120 open clusters, namely, diameter, distance, reddening and age.

• 대한음성학회지:말소리
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• 제65호
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• pp.37-49
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• 2008

The purposes of this experiment were to compare and analyze some voice parameters of the hearing impaired male adults and to suggest a basic data on the speech intervention for the hearing impaired. Voice analysis of four sustained vowels(/a/, /i/, /${\partial}$/, /u/, fundamental Sequency(F0), jitter percent, shimmer percent, and Noise to Harmonic Ratio(NHR) was conducted for the deaf young male adults using a sign laguage(N=5, aged 16-20) and the normal hearing young male adults(N=10, aged 18-20) by using MDVP(Multi-Dimensional Voice Program) in CSL. F0, jitter, and shimmer in the deaf group were significantly higher than those in the normal hearing group. The average of F0 was 151 Hz, which was lower than the results of the previous studies, and there were no significant differences among the sustained vowels. In both groups, the values of the voice parameters were stable on the /a/ or /${\partial}$/, those closed to the standard scores.

• Nuclear Engineering and Technology
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• 제28권4호
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• pp.379-389
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• 1996

To experimentally investigate the several wave patterns for the horizontal countercurrent stratified air-water flow, a series of systematic experimental studies have been performed. The experiments are carried out in a horizontal pipe with 4m in length and 102mm in inner diameter. The oater and air superficial velocities vary from 0.0004 to 0.0204 and from 0 to 6m/s, respectively. The instantaneous water thickness is measured by parallel-wire conductance probes, and the wave field is recorded by high speed video camera. Also, to evaluate the wave effect on interfacial friction factor, the pressure drop is measured. Statistical data anal)sis is accomplished in order to obtain the fundamental wave parameters such as un amplitude, length and velocity, and spatial growth factor. By using these statistical parameters, the wave regime boundaries can be verified.

• 한국조명전기설비학회지:조명전기설비
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• 제5권3호
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• pp.78-83
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• 1991

This study proposes a unified method to design toroidal transformer and its optimal design algorithm. This unified design method was derived from the fundamental equation of power on the basis of electromagnetic energy of a core and the definition of three parameters(K1, K2, KW) that influence the form of a core and the ratio of a core and coil. Accordingly this design method condenses the whole data for design of toroidal transformer to a standard variable which is the inner diameter of a core. The minimal cost, weight and volume values of the transformer were computed by means of the algorithm to search the optimal values of the parameters. Furthermore, through the CAD, the efficiency of this unified design method and optimal algorithm proposed in this paper was confirmed.

• 전기학회논문지
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• 제56권5호
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• pp.841-847
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• 2007

This paper deals with the micro-grid consisting of micro-sources which adopt voltage sourced inverters with independent real and reactive power control capability for providing premium power quality. This paper presents dynamic modeling and the stable operating range of the micro-grid system varying the parameters of the micro-sources. The fundamental frequency model of the micro-source inverters are considered to form a dynamic model of the micro-grid system. Stability analysis is performed based on the linearized dynamic model of the micro-grid system. Case study results show the parameters affecting the stability of the micro-grid and the stable operating range of the micro-sources.

• Earthquakes and Structures
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• 제15권3호
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• pp.263-273
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• 2018

Operational modal analysis is being widely used in aerospace, mechanical and civil engineering. Common research fields include optimal design and rehabilitation under dynamic loads, structural health monitoring, modification and control of dynamic response and analytical model updating. In many practical cases, influence of noise contamination in the recorded data makes it difficult to identify the modal parameters accurately. In this paper, an improved frequency domain method called Enhanced Least Square Complex Frequency (eLSCF) is developed to extract modal parameters from noisy recorded data. The proposed method makes the use of pre-defined approximate mode shape vectors to refine the cross-power spectral density matrix and extract fundamental frequency for the mode of interest. The efficiency of the proposed method is illustrated using an example five story shear frame loaded by random excitation and different noise signals.

• Journal of Astronomy and Space Sciences
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• 제27권2호
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• pp.75-80
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• 2010

Several survey observations have produced light curves of more than five thousand eclipsing binaries for last 15 years. Future missions such as the Large Synoptic Survey Telescope (LSST), the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) and Gaia are expected to yield hundreds thousands of new variable stars and eclipsing binaries. Current methods require a week to analyze the light curves of an eclipsing binary for its physical and orbital parameters. The current methods of analyzing the light curves will be inadequate to treat the overwhelming influx of new data. Therefore we developed a new method to treat large numbers of light curves of eclipsing binaries. We tested the new method by analyzing more than one hundred light curves of the detached and semi-detached eclipsing binaries discovered in the Small Magellan Cloud and present their fitted light curves with observations.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1999년도 봄 학술발표회 논문집
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• pp.343-350
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• 1999

Orthotropic steel bridge decks are potentially liable to cause fatigue cracks due to weld defects, residual stresses, and in-plane or out-of-plane stresses. In particular, the cracks propagated through deckplate in longitudinal rib to deckplate joints occur at weld toe and weld root due to stress concentrations. Numerical parametric studies are performed to show the Influence of the parameters on the stress concentration at the connection between the longitudinal rib and the deckplate. The parameters include root gap, toe angle $\theta$, toe radius $\rho$, and weld penetration. This study provides a fundamental point for the improvement of fatigue resistance and the estimation of the fatigue crack propagation in wekded joint details.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 토목섬유 특별세미나
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• pp.41-50
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• 2000

Segmental retaining wall market in Korea has been growing dramatically since late 1990s in both engineered and non-engineered applications. Despite the inherent conservatism in the current design approaches, numerous major and minor structural problems have been reported during and after construction, covering a range of minor structural damage to total collapse. Much still needs to be investigated to fill the gap between the theory and the practice. This paper reviews several design issues with regard to the segmental retaining walls such as the selection of shear strength parameters for backfill soil, local stability, and tiered wall construction. In addition, the effects of shear strength parameters and the fundamental behavior of tiered SRWs are examined based on the results of finite element analysis. Implications of the findings from this study to current design practices were discussed in detail.

• Journal of information and communication convergence engineering
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• 제6권1호
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• pp.80-85
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• 2008

Images are often corrupted by noises during signal acquisition and transmission. Among those noises, additive white Gaussian noise (AWGN) and impulse noise are most representative. For different types of noise have different characters, how to remove them separately from degraded image is one of the most fundamental problems. Thus, a modified image restoration algorithm is proposed in this paper, which can not only remove impulse noise of random values, but also remove the AWGN selectively. The noise detection step is by calculating the intensity difference and the spatial distance between pixels in a mask. To divide two different noises, the method is based on three weighted parameters. And the weighted parameters in the filtering mask depend on spatial distances, positions of impulse noise and standard deviation of AWGN. We also use the peak signal-to-noise ratio (PSNR) to evaluate restoration performance, and simulation results demonstrate that the proposed method performs better than conventional median-type filters, in preserving edge details.