• Journal of the Korean Crystal Growth and Crystal Technology
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• v.11 no.6
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• pp.264-268
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• 2001

We manipulate properly the partition function of the surface system to evaluate an adsorption isotherm. We explain the dependence of strong interaction on the surface phase transition via analysis of the derived adsorption isotherm. Our theoritical results for adsorption well reflect to the experiments.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.5
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• pp.933-942
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• 1992

The effects of the folwrate on the dropsize from the two-phase coaxial nozzle are investigated by using the direct photographic method and the empirical equation is obtained. For the photography, the light source which the life time is the order of 100ns is fabricated and the lens is the zoom lens which has the MICRO function with a teleconvertor. The distillated water and the compressed air of the surrounding temperature are injected and atomized. For the purpose of the exact adjustment and measurement of the flowrates, the two rotameters are used. As a result of this study, the sauter mean diameter of droplets has a tendency for a logarithmic function with air flowrate and for a exponential function with water flowrate.

• Proceedings of the KIEE Conference
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• 2001.10a
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• pp.57-60
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• 2001

This paper presents a new method for removing reaching phase in variable structure control systems using Bell type switching function. By proposed method, during the entire control process reaching phase is removed. For effective speed control of trapezoidal type brushless DC motor, a time varying switching function based speed controller is developed as illustration.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.637-640
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• 2005

We propose a sound source localization method using the Head-Related-Transfer-Function (HRTF) to be implemented in a given platform. HRTFs contain not only the information regarding proper time delays but also phase and magnitude distortions due to diffraction and scattering by the shading object. Therefore, a set of HRTFs for any given platform provides a substantial amount of information as to the whereabouts of the source. In this study, we introduce new phase criterion in order to find the sound source location in accordance with the HRTF database empirically obtained in an anechoic chamber with the given platform. Using this criterion, we analyze the estimation performance of the proposed method in a household environment.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2008.04a
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• pp.108-113
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• 2008

Virtual construction (VC) system enables project manager to visually check mistakes in design materials by using virtual reality technology. In using VC system, to make 3D object by each construction element is still tedious work. This study suggests an improved method to make 3D object by using parameter-based 3D generation function. The IDEFO model to organize the process for the function. A VC system by this function was developed in this study and the function was verified by a bridge project in this system.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.292-297
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• 2003

A stochastic approach has been presented for superplastic deformation of Ti-6AJ-4V alloy, and probability function are used to heterogeneous phase distributions. The experimentally observed spatial correlation function are developed, and microstructural evolutions together with superplastic deformation behavior have investigated by means of the probability function. The result have shown that the probability varies approximately linearly with separation with distance, and significant deformation enhanced probability changes during the deformation. The stress-strain behavior with the evolutions of probability function can be correctly predicted by the model. The finite clement implementation using Monte Carlo simulation associated with phase re-distributions shows that better agreement with experimental data of failure strain on the test specimen.

• The Pure and Applied Mathematics
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• v.19 no.2
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• pp.147-169
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• 2012

We introduce a Heaviside-function formulation of the interaction between incompressible two-phase fluid and a non-deformable solid. Fluid and solid interact in two ways : fluid satises the Dirichlet boundary condition imposed by the velocity field of solid, and solid is accelerated by the surface traction exerted by fluid. The two-way couplings are formulated by the Heaviside function to the interface between solid and fluid. The cumbersome treatment of interface is taken care of by the Heaviside function, and the interaction is discretized in a simple manner. The discretization results in a stable and accurate projection method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.843-846
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• 2004

Cavity tone is generated due to the feedback between flow and acoustic wave. It is recognized that the period is determined by the time required for the flow convection in one direction, the time required for the acoustic propagation in the other direction and the time for phase shift depending on the flows and mode. Most of the phenomena have been investigated by experiments and a simple but fundamental theory. But the cause of the phase shift and the correctness of the theory have not been clearly explained so far. In this paper, the phenomena are calculated numerically to obtain detail information of flow and acoustic wave to explain the mechanism including the phase. High order high resolution scheme of optimized high order compact is used to resolve the small acoustic quantities and large flow quantities at the same time. The data are reduced using cross correlation function in space and time and cross spectral density function which has phase information. Abrupt change in pressure near corner in cavity is observed and is relate to phase variation. The time required for the feedback between the flow and acoustic wave is calculated after the numerical simulation f3r various modes. The periods based on the time calculated using the above method and direct observation from the acoustic waves generated and propagated in the numerical simulation are compared. It is found that no phase shift is required if we examine the time required carefully. Rossiter's formula for the cavity tone used for quick estimation needs to be modified far some modes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.9A
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• pp.2197-2210
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• 1998

In the grand alliance (GA) HDTV receiver, a coherent detection is empolyed for coherent demodulation of vestigial side-band (VSB) signal by using frequency and phaselocked loop(FPLL) operating on the pilot carrier. Additional phase tracking loop (PTL) employed to track out phase noise that has not been removed by the FPLL in theGA system. In this paper, we propose an algorithm for phase detection which utilizes a weighting function. The simplest implementation of the proposed algorithm using te sign of the Q channel component can be tractable by imposing a phase detection gain to the loop gain. It is obserbed that the propsoed algorithm has a robust characteristic against the performance of the digital filters used for Q channel estimation. A second goal of this paper is to introduce a gain control algorithm for the PTL in order to provide an effective implementation of the proposed phase detection algorithm. And we design the PTL through the realization of the simplified digital filter for H/W reduction. The proposed algorithms and the designed PTL are evaluated by computer simulation. In spite of using the simplified H/W structure, simulation results show that the proposed algorithms outperform the coventional PTL algorithms in the phase detection and tracking performance.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.05a
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• pp.119-121
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• 2022

In this paper, we will make a model that finds optimal phase for each crossroad. When the traffic volume, traffic capacity, and the lane width of every direction is given for each crossroad, we aim to find the most efficient phase. We established an evaluation function that evaluates the efficiency of each phase using the values of the average waiting time in one direction, the average delay time, the standard deviation of the delay time, and the average delay time in each direction. The time allocation to optimize a phase pattern can be obtained by using the gradient decent method. Through this research, we hope to decrease the waiting time in transporation, thus improving the overall traffic condition in cities.