• Bulletin of the Korean Space Science Society
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• 1993.04a
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• pp.16-16
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• 1993

The Cosmic Mach number M is the ratio of the bulk flow velocity of the galaxrvelocity field on some scale R to the unall scale velocity dispersion within refcions of scale R. Because M is the ratio of two velocities, it is inn-dimansionat and the Here, independent of the amplitude of the power specHim and of the biasplnmeter in the linear theory. We have measured the Mach rnlmber for two observational samples: a spiral galaxy sample(AHM) of Aaronson and hiscoBlaborators with absolute distances measured by the infrared Ttillr-Fisher relatioa and an elliptical galaxy sample(EGALS) of Faber or 0, with distances determined by the relation. The effective depths distances of galaxies from the Local Group of these samples are 1639 km/s and 2862 e/s, respectivelr. The Machnumbers from these observed peculiar velocity Selds He fund as M=0.95 for AHMand M=0.59 for EGALS. We comPBre these calculated Mach numbers with thosefrom meck surweys drawn fuom three cosnulogical medels: the stand8rd biased nh=0.5 CDM modet an open CDM rrudel with gh=0.2, and a medd with thepower-law power specelm P(k)-k-1 and n=1. The Mach rnlmber test can give robust constraints on these cosmelogical nudels whose power spectra have very different shapes at large scales.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.387-390
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• 1998

In this paper, HBT's with lower phase noise and passive elements, such as resistors, capacitors and inductors, for resonance and impedance matching networks are designed, fabricated, tested, and carefully analysed, respectively, and then, they are integrated for the design and fabrication of functional X-band oscillators with lower phase noise. Epi-wafers for HBT's with the structure of graded $Al_{x}$G $a_{1-x}$ As emitter and C-doped base layer of 700.angs. thick were used to specially emphasize the improvement of $f_{T}$ and $f_{max}$, and the lowering of phase noise, in design aspects. At the test frequencies of 12GHz, capacitances of MIM capacitors, spiral inductor, and resistances are 0.5~10pF, 0.4~11.06nH, and 20~1,380.ohm., respectively. The emitter size of HBY's for the X-band MMIC oscillators is 3*10u $m^{2}$, and find chip size is 0.9*0.9m $m^{2}$..EX>.

• Structural Engineering and Mechanics
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• v.18 no.5
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• pp.591-607
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• 2004

The substance of the use of the derived non-linear creep constitutive equations under variable stress levels (see first part of the paper, Kmet 2004) is explained and the strategy of their application is outlined using the results of one-step creep tests of the steel spiral strand rope as an example. In order to investigate the creep strain increments of cables an experimental set-up was originally designed and a series of tests were carried out. Attention is turned to the individual main steps in the production and application procedure, i.e., to the one-step creep tests, definition of loading history, determination of the kernel functions, selection and definition of constitutive equation and to the comparison of the resulting values considering the product and the additive forms of the approximation of the kernel functions. To this purpose, the parametrical study is performed and the results are presented. The constitutive equations of non-linear creep of cable under variable stress history offer a strong tool for the real simulation of stochastic variable load history and prediction of realistic time-dependent response (current deflection and stress configuration) of structures with cable elements. By means of suitable stress combination and its gradual repeating various loads and times effects can be modelled.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.62.2-62.2
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• 2016

We present a newly developed algorithm based on a Bayesian method for 2D tilted-ring analysis of disk galaxies which operates on velocity fields. Compared to the conventional ones based on a chi-squared minimisation procedure, this new Bayesian-based algorithm less suffers from local minima of the model parameters even with high multi-modality of their posterior distributions. Moreover, the Bayesian analysis implemented via Markov Chain Monte Carlo (MCMC) sampling only requires broad ranges of posterior distributions of the parameters, which makes the fitting procedure fully automated. This feature is essential for performing kinematic analysis of an unprecedented number of resolved galaxies from the upcoming Square Kilometre Array (SKA) pathfinders' galaxy surveys. A standalone code, the so-called '2D Bayesian Automated Tilted-ring fitter' (2DBAT) that implements the Bayesian fits of 2D tilted-ring models is developed for deriving rotation curves of galaxies that are at least marginally resolved (> 3 beams across the semi-major axis) and moderately inclined (20 < i < 70 degree). The main layout of 2DBAT and its performance test are discussed using sample galaxies from Australia Telescope Compact Array (ATCA) observations as well as artificial data cubes built based on representative rotation curves of intermediate-mass and massive spiral galaxies.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.930-935
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• 2001

The experimental characterization of hydrodynamic bearing spindle motor is performed for the practical implementation of high-performance hard disk drive system. Firstly, the design concept of hydrodynamic bearing for the disk drive system is addressed including the herringbone grooved journal bearing, the spiral grooved thrust bearing, capillary seal design, and the viscous pumping of fluid. Secondly, the experimental evaluation is performed for the disk drive system in which the hydrodynamic bearing spindle motor is implemented and its dynamic performances are compared with conventional ball-bearing spindle motor. The key parameters include NRRO(Non Repeatable Run-Out), disk dynamics, acoustics, and resultant PES (Position Error Signal). Finally, the external gyro-exciting test results including 200k CSS(Continuous Start-Stop) on three angular attitudes(0,90, 180 degree) are presented in order to verify the practical reliability of disk drive system subject to the gyro-motion of hydrodynamic bearing spindle motor.

• The Journal of Korean Association of Computer Education
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• v.19 no.6
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• pp.55-68
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• 2016

Informatics curriculum revised 2015 proposed the use of block type and text type of programming language by organizing problem solving and the programming unit in a spiral. The purpose of this study is to find out whether the algorithms helps programming learning and whether there is a positive transition effect in block type programming learning to text type programming trailing learning. For 15 elementary school students was conducted block type and text type programming learning. As a result of the research, it is confirmed that writing the algorithm in a limited way can interfere with the learner's expression of thinking, but the block type programming learning has a positive transition to the text type programming learning. This study is meaningful that it suggested a plan for the programming education which is sequential from elementary school.

• Journal of the Korean Institute of Telematics and Electronics
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• v.9 no.5
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• pp.27-33
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• 1972

This paper describes the computer-aided design, fabrication and performance of high Q and high gain active filters suitable for microminiaturization in the frequency range of 10-800MHz, based on the negative resistance operation of a transistor. 48 as high as 1000 and a transducer gain as high as 35dB can readily be obtained with a single-transistor amplifier and with an inductance as small as a few nH at higher frequencies and 150 nH at lower frequencies in tile above frequency range. The gain of the proposed active filter can be stoabilized within $\pm$ 1.5 dB over the temperature range -1$0^{\circ}C$ to +5$0^{\circ}C$ and the temperature dependence of the center frequency is tapicalla 50ppm/$^{\circ}C$. An experimental FM receiver utilizing these fitters and operating at a carrier frequency of 92 MH3 was built. The whole circuit was fabricated on eight alumina substrates of by the thick-film hybrid IC technique and the coils are constructed, for miniaturization, in a spiral form of 3 or 4 turns of enamel copper wire with an overall diameter of about 5mm. The test results are also reported in this paper.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.5
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• pp.666-672
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• 2001

Experiments have been carried out to investigate the evaporation heat transfer characteristics of various tubes on which hydrophilic surface treatment using plasma was employed. Spiral, corrugated and low-finned tubes were selected as test tubes. The evaporator tubes were bundled to form three rows of tubes connected in series, with each row being 400mm long. The results obtained indicate that hydrophilic treated tubes tested exhibit better evaporation heat transfer performance as compared with untreated tubes. It is found that the high wettability of the surface obtained through hydrophilic treatment induces film flow onto the tubes during the evaporation process, while sessile drops are formed on untreated tubes.

• Reproductive and Developmental Biology
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• v.34 no.2
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• pp.63-71
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• 2010

The spontaneous mutant circling mouse (cir/cir) shows a circling behavior and hearing loss. We produced transgenic mice overexpressing transmembrane inner ear (tmie) gene, the causative gene, for the phenotypic rescue of the circling mouse. Through the continuous breeding with circling mice, the cir/cir homozygous mice carrying the transgene (cir/cir-tg) were produced. The rescued cir/cir-tg mice were able to swim in the water with proper orientation and did not show any circling behavior like wild type mice. Western blot and immunohistochemical analysis exhibited that the transgenic tmie was expressed in the inner ear. Inner and outer hair cells were recovered in the cochlea and spiral ganglion neurons were also recovered in the rescued mice. Auditory brainstem response (ABR) test demonstrated that the cir/cir-tg mice are able to respond to sound. This study demonstrates that tmie transgene can recover the hearing impairment and abnormal behavior in the circling mouse.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.26 no.4
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• pp.151-157
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• 2014

An algebraic scroll expander has been fabricated and tested in a R134a Rankine cycle with heat source of 20 kW. For the operating conditions of 20~26 bar and $90{\sim}93^{\circ}C$ at the expander inlet and 8~9 bar at the outlet, the expander produced the shaft output power of about 0.6~0.7 kW in the operating speed range of 1500~2000 rpm. These correspond to the expander efficiency of 40~45%. The volumetric efficiency increased with increasing of the expander speed, reaching to 80% at 2000 rpm. Comparing to numerical simulation results, mechanical efficiency from the test data was found to be considerably low by as much as 30%, indicating that reduction in the frictional loss should be made to improve the scroll expander efficiency.