• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2000.04a
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• pp.75-81
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• 2000

Water waves propagate over irregular bottom bathymetry are transformed by refraction, diffraction, shoaling, reflection etc. Principal factor of wave transform is bottom bathymetry, but in case of current field, current is another important factor which effect wave transformation. The governing equation of this study is develop as wave-current equation type to investigate the effect of wave-current interaction. This wave-current model was applied to the Kwangan beach which is located at Pusan. The numerical simulation results of this model show the characteristics of wave transformation and flow pattern around the Kwangan beach fairly well.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.04a
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• pp.229-232
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• 1997

A free space transmission method using standard gain horn antennas in the frequency range from 9.0 to 10.5GHz is applied to determine the dielectric properties of grain such as rough rice, brown rife and barley. The dielectric constant and loss factor, which depend on the moisture content of the wetted grain are obtained from the measured attenuation and phase shift by vector network analyzer. The effect of density fluctuation, which is an important parameter governing the dielectric properties of grain, on the dielectric constant and loss factor is presented. A new density-independent model in terms of measured attenuation and moisture density is proposed for reducing the effects of density fluctuation on the moisture content measurement.

• Tribology and Lubricants
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• v.19 no.6
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• pp.349-356
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• 2003

A damper floating ring seal with round hole pattern surfaces is suggested for better leakage control. The flat plate test of the round hole pattern surfaces has been performed to yield an empirical friction factor model. The exact predictions of the lock­up position of the damper floating ring, the leakage performance, and the rotordynamic coefficients of the seal are necessary to evaluate the rotordynamic performance of the turbo pump unit. The governing equations including the empirical friction factor model for round hole pattern surfaces are solved by the Fast Fourier Transform method. The lock­up position, leakage flow rate, and rotordynamic coefficients are evaluated according to the geometric parameters of the damper floating ring seal. Theoretical results show that the damper floating ring seals yield less leakage and better rotordynamic stability than the floating ring seal with a smooth surface.

• Advances in nano research
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• v.8 no.4
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• pp.283-292
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• 2020

In the present research, differential quadrature (DQ) method has been utilized for investigating free vibrations of porous functionally graded (FG) micro/nano beams in thermal environments. The exact location of neutral axis in FG material has been assumed where the material properties are described via porosity-dependent power-law functions. A scale factor related to couple stresses has been employed for describing size effect. The formulation of scale-dependent beam has been presented based upon a refined beam theory needless of shear correction factors. The governing equations and the associated boundary conditions have been established via Hamilton's rule and then they are solved implementing DQ method. Several graphs are provided which emphasis on the role of porosity dispersion type, porosity volume, temperature variation, scale factor and FG material index on free vibrational behavior of small scale beams.

• Proceeding of EDISON Challenge
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• 2017.03a
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• pp.128-131
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• 2017

We explore the inverse electron demand Diels-Alder reactions of tetrazines with various functional groups employing quantum calculations. In general, the rate of inverse electron demand Diels-Alder reaction depends on molecular orbital levels of electron donor and electron acceptor. Likewise, ${\pi}$ orbital of the dienophile and ${\pi}^*$ orbital of the diene is a key factor. In this work, we discuss the case where the energy of diene's ${\pi}^*$ molecular orbital is not the sole governing factor to determine the reaction rate, rather the rate shows strong correlation with the charge density of dienes.

• Journal of Electrical Engineering and information Science
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• v.2 no.4
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• pp.72-78
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• 1997

A free space transmission method using standard gain horn antennas in the frequency range from 9.0 to 10.5GHz is applied to determine the dielectric properties of grain such as rough rice ,brown rice and barley. The dielectric constant and loss factor, which depend on the moisture content of the wetted grain are obtained from the measured attenuation and phase shift by vector network analyzer. The moisture content of grain varied from 11 to 25% based on this wetted condition. The measured values of dielectric constants as a function of moisture density are compared with values of those obtained using he predicted model for estimating dielectric constants of grain. The effect of density fluctuation, high is an important parameter governing the dielectric properties of grain, on the dielectric constant and loss factor is presented. A new density-independent model in terms of measured attenuation an moisture density is proposed of reducing the effects of density fluctuation on the moisture content measurement.

• Transactions of The Korea Fluid Power Systems Society
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• v.6 no.4
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• pp.24-32
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• 2009

For a design of on/off solenoid actuator for valve actuating, designer must have the experimental knowledge as well as general electromagnetic formulas to design object. It is possible for theoretical knowledge to do the out-line design, but it is impossible to optimal design without experimental knowledge which only can be achieved through many repeated experiments. In addition, in present on/off type solenoid actuator field, the smaller, lightening, lower consumption power, high response time are effected as the most important design factor. So, experimental knowledge is more needed for optimal design of solenoid actuator. In this study, we derived the governing equations for optimal design of on/off solenoid actuator for valve actuating and developed a design program composed electromagnetic theories and experimental parameter values for inexperienced designers. And we proved the propriety of this program by experiments.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.04a
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• pp.327-334
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• 2002

The global behavior of tube structures (including tube and tube(s)-in-tube constructions) is investigated for the behavioral characteristics of the structures and their performance in relation to the various structural parameters. The stiffness factor in terms of the axial stiffness of the columns and the bending stiffness of both columns and beams is chosen as a parameter to explain the global behavior of the structures. The shear-lag phenomenon is also discussed to explain the general behavior of the structures. Three types of tube structures, with various structural parameters, are analysed for the comparative study, and the results are compared to investigate the structural response and performance of such structures. As a result of the comparison it is obtained that the axial stiffness of the columns is the most important factor governing the response of the tube structures under lateral loading

• Proceeding of EDISON Challenge
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• 2016.11a
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• pp.101-105
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• 2016

Prandtl's Lifting-line theory is the classical theory of calculating aerodynamic properties. Though it is classical method, it predicts the aerodynamic properties well. By lifting-line theory, high aspect ratio is critical factor to decrease induced drag. And 'elliptic-similar' wing also makes the minimum induced drag. But due to the problem of manufacturing, tapered wing is preferred and have been utilized. In this Paper, by using Edison CFD, verifying the classical lifting-line theory. To consider induced drag only, using Euler equation as governing equation instead of full Navier-Stokes equation. Refer to the theory, optimum taper ratio which makes the minimum induced drag is 0.3. Utilizing the CFD results, plotting oswald factor over various taper ratio and investigating whether the consequences are valid or not. As a result, solving Euler equation by EDISON CFD cannot guarantee the theoretical values because it is hard to set the proper grid to solve. Results are divided into two cases. One is the values are decreased gradually and another seems to following tendency, but values are all negative number.

• Carbon letters
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• v.14 no.4
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• pp.255-258
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• 2013

Flexible transparent conducting films (TCFs) were fabricated by dip-coating single-wall carbon nanotubes (SWCNTs) onto a flexible polyethylene terephthalate (PET) film. The amount of coated SWCNTs was controlled simply by dipping number. Because the performance of SWCNT-based TCFs is influenced by both electrical conductance and optical transmittance, we evaluated the film performance by introducing a film property factor using both the number of interconnected SWCNT bundles at intersection points, and the coverage of SWCNTs on the PET substrate, in field emission scanning electron microscopic images. The microscopic film property factor was in an excellent agreement with the macroscopic one determined from electrical conductance and optical transmittance measurements, especially for a small number of dippings. Therefore, the most crucial factor governing the performance of the SWCNT-based TCFs is a SWCNT-network structure with a large number of intersection points for a minimum amount of deposited SWCNTs.