• 대한전기학회:학술대회논문집
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• 대한전기학회 1987년도 전기.전자공학 학술대회 논문집(II)
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• pp.874-877
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• 1987

In this paper a DPLL circuit realizable by digital IC's is propose and the principles of general DPLL are described. An all Digital phase locked loop is designed, analyzed, and tested. In particular, the approach of invoking Gaussian assumption on the decision variable and based on S.O.Rices theory is used. As a performance of the above PLL detector operating on low data rate FSK is given and demonsrtated to be FSK reception.

• Wind and Structures
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• 제20권6호
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• pp.811-827
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• 2015

This study presents experimental and numerical aerodynamic investigation of a prototype vehicle. Aerodynamics forces examined which exerted on a prototype. This experimental study was implemented in a wind tunnel for the Reynolds number between $10^5-3.1{\times}10^5$. Numerical aerodynamic analysis of the vehicle is conducted for different Reynolds number by using FLUENT CFD software, with the k-$\varepsilon$ realizable turbulence model. The studied model aims at verifying the aerodynamic forces between experimental and numerical results. After the Reynolds number of $2.8{\times}10^5$, the drag coefficient obtained experimentally becomes independent of Reynolds number and has a value of 0.25.

• Journal of Advanced Research in Ocean Engineering
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• 제2권2호
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• pp.61-66
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• 2016

This study presents the wave run-up height and depression depth around offshore cylindrical structures according to the wave period. The present study employs the volume of fluid method with the realizable turbulence model based on a commercial computational fluid dynamics software called the "STAR-CCM+" to simulate a 3D incompressible viscous two-phase turbulent flow. The present results for the wave run-up height and depression depth with regard to the wave period are compared with those of the relevant previous experimental and numerical studies.

• 전자공학회논문지S
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• 제34S권1호
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• pp.94-104
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• 1997

Most color imaging devices often exhibit color distortions due to the differences in realizable color gamuts and nonlinear characteristics of their components. In order to minimize color differences, it is desirable to apply color correction techniques. Th efirst step of color correction is to select the subset of the color coordinates representing the input color space. Th eselected subset serves as so called color samples to model the color distortion of a given color imaging device. The effectiveness of color correction is determined by the color sampels utilized in the modeling as well as the applied color correction technique. This paper presents a new selection method for color samples based on gentic algorithm. In the proposed method, structure of strings are designed so that the selected color samples fully represent the characteristics of color imaging device and consist of distinct color coordinates. To evaluate the performance of the selected color samples, they ar etuilized for three different color correction experiments. The experimentsal results are comapred with the crresponding results obtianed with the equally spaced color samples.

• Transactions on Control, Automation and Systems Engineering
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• 제3권4호
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• pp.272-282
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• 2001

Uncertainties are the main reasons of deterioration of contour control of industrial articulated robot arm. In this paper, a high-precision contour control method was proposed to overcome some main uncertainties, such as torque saturation, system delay dynamics, interference between robot links, friction, and so on. Firstly, each considered factor of uncertainties was introduced briefly. Then proper realizable objective trajectory generation was presented to avoid torque saturation from objective trajectory. According to the model of industrial articulated robot arm, construction of Gaussian neural network controller with considering system delay dynamic, interference between robot links and friction was explained in detail. Finally, through the experiment and simulation, the effectiveness of proposed method was verified. Furthermore, based on the results it was shown that the Gaussian neural network controller can be also adapted for the various kinds of friction and high-speed motion of industrial articulated robot arm.

• 한국비블리아학회지
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• 제7권1호
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• pp.43-101
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• 1994

In this study all kinds of Library Associations in Korea counted as Library Coperatives are surveyed under the categories of their collaborative activities as well historical developments. The results of this study are as follow : 1) The library cooperatives which have more working personnel are carrying out interlibrary cooperations more effectively, than those which have fewer working personnel. 2) The library cooperatives operating with established and realizable regulations or rules are more progressive in interlibrary cooperations than those operating with traditional practices or customary rules. 3) The library cooperatives with executing committee appear to be more progressive in interlibrary cooperations than those without it. 4) Both updating frequency of union catalog or union list and publishing intervals of supplementary editions are proved to be an important factor affecting the effectiveness of interlibrary cooperations. 5) Three of library cooperatives are employing the systems for payment of information provisions in interlibrary cooperations but the other library cooperatives are employing no payment systems, or not following such systems. By the results, six kinds of suggestions to improve the activities of korean library cooperatives have been expressed.

• 한국전산유체공학회지
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• 제20권1호
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• pp.57-64
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• 2015

This paper describes a volume of fluid(VOF) method, mRHRIC for the simulation of free surface flows around ship hulls and provides its validation against benchmark test cases. The VOF method is developed on the basis of RHRIC method developed by Park et al. that uses high resolution differencing schemes to algebraically preserve both the sharpness of interface and the boundedness of volume fraction. A finite volume method is used to solve the governing equations, while the realizable ${\kappa}-{\varepsilon}$ model is used for turbulence closure. The present numerical results of the resistance performance tests for DTMB5415 and KCS hull forms show a good agreement with available experimental data and those of other free surface methods.

• 대한기계학회논문집
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• 제19권3호
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• pp.820-833
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• 1995

An analysis is performed to examine the equilibrium state and the stability of modeled Reynolds stress equations for homogeneous turbulent shear flows. The system of the governing equations consists of four coupled ordinary differential equations. The equilibrium states are found by the steady state solution of the governing equations. In order to investigate the stability of the system about its state in equilibrium, and eigenvalue problem is constructed. As a result, constraints for the coeffieients in the model equations are obtained by the stability condition of the equilibrium state as well as by their physically realizable bounds. It is observed that the models with pressure-strain rate correlation that are linear in the anisotropy tensor are stable and produce reasonable equilibrium tensor do not behave properly. Stability considerations about three most commonly used models are given in detail in the final section.

• 소음진동
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• 제10권4호
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• pp.648-654
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• 2000

A procedure to determine the realizable optimal positions of rigid supports is suggested to get a maximum fundamental natural frequency. a measured frequency response function based substructure-coupling technique is used to model the supported structure. The optimization procedure carries out the eigenvalue sensitivity analysis with respect to the stiffness of supports. As a result of such stiffness optimization, the optimal rigid-support positions are shown to be determined by choosing the position of the largest stiffness. The optimally determined support conditions are verified to satisfy the eigenvalue limit theorem. To demonstrate the effectiveness of the proposed method, the optimal support positions of a plate model are investigated. Experimental results indicate that the proposed method can effectively find out the optimal support conditions of the structure just based on the measured frequency response functions without any use of numerical model of the structure.

• 한국산업정보학회논문지
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• 제17권2호
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• pp.29-32
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• 2012

Computer generated holography (CGH) is technology for generating holograms of synthetic, three dimensional (3D) objects which may not exist in the physical world. The process, however, requires heavy amount of computation as the resolution of a hologram is significantly higher than that of a typical optical image. This paper reviews four modern techniques for fast generation of digital Fresnel holograms which are important in the development of holographic video systems. The methods that will be described include the virtual window, sub-line, wavefront recording plane (WRP), and the interpolative WRP schemes. These works share the common objective to generate digital Fresnel hologram at a speed that is close to the video frame rate, and with complexity which is realizable with affordable computing and reconfigurable hardware devices. The author will present the principles and realization of these works, as well as some potential area of research in digital holography.