• Journal of the Korean Institute of Landscape Architecture
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• v.30 no.4
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• pp.9-18
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• 2002

This study investigated the influential range of landmarks and the relationship between landmarks and cognition factor so as to offer basic data to be used for the effective use and the management of landmarks. In this study, eighteen famous landmark in Seoul were selected and analyzed. The result of this study can be summarized as follows : 1) First, eighteen determining elements of cognition factors were selected via documents survey. Second, general cognition factors of landmarks were analysed using these elements through questionnaires to specialists. As a result of factor analysis, historic cultural factor, scale factor, visual form factor, locational factor and uniqueness factor were revealed. 2) According to revealed cognition factor, eighteen landmarks are categorized into four types using MDS method via questionnaire to resident in Seoul city. These four types of landmarks are: type I that are recognized by historic cultural factor; type II that are recognized by scale factor; type III that are recognized by uniqueness factor; and type IV that are recognized by visual form factor. 3) As the result of regression, the influential range of landmarks were revealed at about a 10km radius(type I : 12km type II : whole area of Seoul city≒15km, typeIII : 8.7km, typeIV : 8.5km). 4) As a result of analysing the correlation between the influential range and the cognition factor through multiple linear regression analysis, the locational factor is the main factor affecting the influential range of landmarks in every type. The uniqueness factor comes next, which affects influential range partially. 5) Except type 1, as a result of analysing the correlation between influential range and the physical heights of landmarks, a quadratic equation is revealed, showing that the influential range of landmarks over 200 meters in height shows a radical change. Landmarks can be used as reinforcement tools of legibility, effective tools for landscape management and for the improvement of a community's image. This study on the influential range of landmarks and main cognition factor can be utilized as a landmark management plan and in urban planning, such as a new town plan.

• School Mathematics
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• v.6 no.4
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• pp.325-344
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• 2004

This study was carried out to investigate effects of the mindmap note-taking for the formation of the mathematical concepts structure and the matjematical creativity. Two classes were randomly chosen for this study from the third grade students of a middle school located in a medium size city. Thirty one lecture hours of the mindmap note-taking on the quadratic equation and functions were administered to the experimental class of 41 students, while same lecture hours of the ordinary instruction on the same contents were administered to the control class of 40 students. It was shown from this experiment that there ware significant evidences of improvement both in the formation of students' mathematical concepts structure and mathematical creativity through the mindmap note-taking lecture. Hence, the mindmap note-taking lecture is suggested for the improvement in the formation of student's mathematical concepts structure and mathematical creativity.

• The Journal of the Acoustical Society of Korea
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• v.21 no.2
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• pp.134-141
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• 2002

In this paper, a free wake analysis based on the curved vortex element and CVC wake model is used to predict the aerodynamic performance and noise for HAWT. Also for prediction of RPM, a maximum value through a quadratic regression was suggested. And for a noise prediction, the broadband noise prediction method based on experimental equation was used. The curved vortex element uses a BCVE and an SIVE instead of a straight vertex element. In the CVC wake model, the vortex strengths are assumed to be constant along a span and a vortex filament. The free wake structure made by the curved vortex element and CVC was substituted for a vortex lattice, so it has an advantage for the less calculation time and a depiction of accurate wake structure. For the verification of this program, calculated results are compared with Mr. Kim's experiment model and Zond Z-40FS for performance and with WTS-4 and USWP models for noise. Good agreements are obtained between the predicted and the measured data for the performance and far-field noise spectra.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.8
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• pp.3611-3616
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• 2013

Physical characteristics of a magneto-rheological(MR) fluid can be influenced by a magnetic field. In the present study, the behaviors of MR fluid are visualized and the shear stresses are measured under the magnetic field for density 1.3, 1.5 and 1.7 $g/cm^3$, and viscosity 100, 1000 and 10000cp. When the magnetic field is applied, particles of MR fluid are arranged along lines of magnetic field. It is observed that the flow pattern of MR fluid under the magnetic field is different from that of MR fluid without the magnetic field. Shear stress of MR fluids under the magnetic field changes significantly. Shear stress by the magnetic field increases the shape of a quadratic equation. When the density changes from $1300kg/m^3$ to $1700kg/m^3$ at 2.0A, the shear stress increases about 33%.

• Journal of the Earthquake Engineering Society of Korea
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• v.9 no.3 s.43
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• pp.33-42
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• 2005

Frequency domain Volterra model is applied to nonlinear parameter identification procedure for dynamic systems modeled by nonlinear function. The frequency domain Volterra kernels, which correspond io linear, quadratic, and cubic transfer functions in lime domain, are incorporated in nonlinear parametric identification procedure. The nonlinear transfer functions, which can be derived from the Volterra series representation of the nonlinear differential equation of the system by Schetzen's method(1980), are directly used for modeling input output relation. The error is defined by the difference between the observed output and the estimated output which is calculated by substituting the observed input to nonlinear frequency domain model. The system parameters are searched by minimizing the error. Volterra model guarantees enough accuracy and convergence and the estimated coefficients have a good agreement with their actual values not only in the linear frequency region but also in the legion where the $2^{nd}\;or\;3^{rd}$ order nonlinearity is dominant.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.12C
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• pp.1184-1193
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• 2006

Image interpolation has been widely used and studied in the various fields of image processing. There are many approaches of varying complexity and robustness. In this paper, a new distance weight is proposed for the conventional linear interpolation. In comparison with the conventional linear weight, the new distance weight uses a quadratic or cubic polynomial equation to reflect that the interpolated value should be influenced more by the value of closer pixels in an input image. In this paper, the new adaptive linear (NAL) interpolation, which considers patterns near the interpolated value, is also proposed. This algorithm requires a pattern weight, which is used to determine the ratio of reflection on local patterns, to obtain an interpolated image that exhibits better quality at various magnification factors (MF). In the computer simulation, not only did the NAL interpolation exhibit much lower computational complexity than conventional bicubic interpolation, it also improved peak signal-to-noise ratios (PSNR).

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.5
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• pp.404-414
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• 2013

In the conceptual design phase of jet fighters, the trade study is performed repeatedly for a selection of the baseline configuration. The automation of repeated trade study makes possible to select efficiently the baseline configuration. In this study, the performance analysis code was developed for the automation of trade study. The code was consists of the module of shape generation, the module of weight estimation, the module of mission performance analysis. 3D CAD Model can be generated by the module of shape generation and Weight can be estimated by using the empirical equation in the module of weight estimation. The module of mission performance analysis was able to calculate the mission performance about the arbitrary mission profile. In addition, the optimal mission performance can be calculated by using optimization method. By performing the validation, the code was confirmed to be able to apply to the conceptual design phase.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.10
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• pp.7118-7125
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• 2015

This study examined one of the concerned or even imperative issues in the field of contemporary finance related to approaching an optimal level of cash holdings for the firms belonging to the chaebols in the Korean domestic capital markets. However, the subject may not have been drawn much attention so far, even if there are still ongoing and active debates among the interest parties at the macro- or micro-level. Two primary hypotheses were postulated to be empirically tested. On the results of the first hypothesis test for the existence of an optimal cash reserves for the sample firms, two estimation techniques were performed in terms of a quadratic regression equation and a relationship between a firm's value and the residuals derived from the static panel date model. As a primary financial implication of the study which may contribute to the practitioners and the academics in finance, the optimal level of cash holdings can be estimated by controlling for the a priori significant components for the sample firms towards maximizing firm value.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.3
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• pp.1247-1252
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• 2014

In the present study, sedimentation and shear stress of MR fluid are investigated to physical characteristics of MR fluid along temperature conditions. MR fluid is a suspension of micrometer-sized magnetic particles in a base liquid. Therefore, dispersion of MR fluid is important in the case of the design and optimization of the system using MR fluid. Due to sedimentation characteristics of MR fluid by magnetic particles, the sedimentation and shear stress of commercial MR fluid are investigated at $25^{\circ}C$ and $80^{\circ}C$ temperatures by using a forced convection oven and a viscometer. From experimental results, the sedimentation and shear stress are more affected by the temperatures of $80^{\circ}C$ than $25^{\circ}C$ and the mixing time of 5min than 10min. Shear stress by the applied current increases the shape of a quadratic equation and are lower 6-18% at $80^{\circ}C$ than $25^{\circ}C$.

• Journal of the Korean Institute of Intelligent Systems
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• v.26 no.1
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• pp.16-22
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• 2016

The research on two-wheeled inverted pendulum (TWIP) mobile robots has been ongoing in a number of robotic laboratories around the world. In this paper, we consider a robust controller design for the TWIP mobile robot driving on uniform slopes. We use a 2 degree-of-freedom (DOF) model which is obtained by restricting the spinning motion in a 3 DOF motion dynamic equation. In order to design the robust controller guaranteeing stability of the TWIP mobile robot driving on inclined surface, we propose a sliding mode control based on the theory of variable structure systems and design a sliding surface using the theory of the linear quadratic regulation (LQR). For simulation, the dynamic model of the TWIP mobile robot is constructed using Mathworks' Simulink and the sliding mode control is also implemented using Simulink. From simulation results, we show that the proposed controller effectively controls the TWIP mobile robot driving on slopes.