• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.931-936
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• 1993

Optimal model following control scheme is to design the controller which makes the response of real system follow that of desirable model. This kind of design scheme is developed for first order system. We extends the scheme for second order system regarding the characteristics of mechanical second order system for vibration suppression of flexible structures. The model of mechanical second order system is obtained using suitable damping ratios and natural frequencies. Using this scheme, we can design the good controller which uses the characteristic of second order system. Numerical examples are presented which were used optimal model following control scheme.

• Journal of Environmental Science International
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• v.15 no.11
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• pp.1069-1075
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• 2006

Starting from Jan. 1, 2006, pursuant to Article 28 of the Natural Environment Conversation Act for development acts with natural Landscape as a subject, the Consultation System on the Effects of Natural Landscape has been put into force in order to, in advance, analyze and predict the effects of natural Landscape according to the implementation of various development plans and development projects and also minimize adverse effects by preparing plans to reduce the effects. The consultation on the effects of natural Landscape is based on the objective and scientific approaches of data with Landscape to minimizing the effects of natural Landscape by developments with the preservation, restoration, outlook and harmonization as basic principles, and looking into the review of natural Landscape damage and harmonization of the site to be developed. For more objectively analyzing the visual effects of natural Landscape according to development acts, the purpose of this study is to provide basic materials of continued Landscape management plans in the planning stage of development plans and after the completion of developments by analyzing the sensitivity of Landscape and deriving areas, whose Landscape will be damaged, mainly focusing on the area of visibility using GIS.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.10 no.5
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• pp.1-9
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• 2007

Local government with abundant natural resources should consider the nature conservation oriented planning process for the sustainable development. With this regard, the aim of this study is to provide a substantial methodology to support the decision-making process to designate the conservation areas. The objectives of the proposed methodology is to conserve natural resources in the local government's territory through quantitatively assessing the values of the natural resources based on various ecological factors such as topography, flora and fauna. In order to test the usability of the method, Gangneung City in Kangwon-Do is selected considering the latest data availability. Based on the assessment process land use of the subjected city could be categorized into 4 levels of conservative area, conservative level 1 area, conservative level 2 area, and conservative level 3 area. Among them, conservative area and conservative level 1 area could be combined as natural resources conservation area and the others could be regarded as buffer and transitional area. Especially conservation area is surrounded by conservation level 2 area. Conclusively, the GIS methods adopted in this could be the efficient illustrative tool to assess the local natural resource values with the central government established nature-environmental information systems.

• Tunnel and Underground Space
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• v.23 no.3
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• pp.192-202
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• 2013

The domestic demand of natural gas has increased continuously due to the sudden rise of oil price and regulations on greenhouse gas to global warming. In order to improve the supply security of natural gas market in Korea, the agreement on supply of pipeline natural gas (PNG) in Russia was signed between Gazprom and Korea Gas Corporation in 2008. If the supply plan of Russian natural gas is realized, underground storage facilities would be required in order to balance supply and demand of natural gas because the gas demand is concentrated in the winter. This study investigated the safety of the storage facility in quantitative way considering several design parameters such as gas pressure, depth of the storage cavern, rock condition and in-situ horizontal stress ratio. Two dimensional stress analyses were conducted using axi- symmetry condition to examine the behavior of cavern depending upon suggested design parameters. Results showed that the factor of safety, defined as the ratio of 'shear strength'/'shear stress', was largely affected by the depth, rock class and gas pressure but was insensitive to the coefficient of lateral pressure(Ko).

• Structural Engineering and Mechanics
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• v.77 no.5
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• pp.601-612
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• 2021

To study the vibration characteristics of a high-speed railway continuous girder bridge-track coupling system (HSRCBT), a coupling vibration analysis model of an m-span continuous girder bridge-subgrade-track system with n-span approach bridge was established. The model was based on the energy and its variational method, where both the interlaminar slip and shear deformation effects were considered. In addition, the free vibration equations and natural boundary conditions of the HSRCBT were derived. Further, according to the coordination principle of deformation and mechanics, an analytical method for calculating the natural vibration frequencies of the HSRCBT was obtained. Three typical bridge-subgrade-track coupling systems of high-speed railway were taken and the results of finite element analysis were compared to those of the analytical method. The errors between the simulation results and calculated values of the analytical method were less than 3%, thus verifying the analytical method proposed in this paper. Finally, the analytical method was used to investigate the influence of the number of the approach bridge spans and the interlaminar stiffness on the natural vibration characteristics of the HSRCBT based on the degree of sensitivity. The results suggest the approach bridges have a critical number of spans and in general, the precision requirements of the analysis could be met by using 6-span approach bridges. The interlaminar vertical compressive stiffness has very little influence on the low-order natural vibration frequency of HSRCBT, but does have a significant influence on higher-order natural vibration frequency. As the interlaminar vertical compressive stiffness increases, the degree of sensitivity to interlaminar stiffness of each of the HSRCBT natural vibration characteristics decrease and gradually approach zero.

• Journal of Fashion Business
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• v.13 no.6
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• pp.147-156
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• 2009

In this study, one of disadvantages is to improve the durability of natural dyeing. In order to enhance linkage of Chitosan or Linkage of between Chitosan and cotton fabrics, effect of increasing amount of Silane on Chitosan durability and possibility of using Chitosan as natural mordant were reviewed. After treatment of chitosan with silane, color effect is similar to dyeability used metal mordant. And the durability's washing fastness and air permeability as using chitosan with silane is better than treatment of metal mordant. Chitosan with silane can perform the natural mordant.

• Advances in Energy Research
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• v.2 no.2
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• pp.61-72
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• 2014

This paper's aim is to do a global evaluation (considering four dimensions: technical-economic, environmental, social and political) in the ways of natural gas transportation (gas pipelines, GNL and GTL) and electric transmission, in order to supply the energy demands of Mato Grosso do Sul, a brazilian state. The transport ways had been compared between itself using a software of decision taking (Decision Lens Suite), which determined a better way for transporting natural gas in this case. In a generalized manner the gas pipeline is the best way of transporting natural gas, therefore it takes advantage in the majority of the analyzed dimensions.

• Structural Engineering and Mechanics
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• v.75 no.3
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• pp.311-325
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• 2020

In applying the spectral stochastic finite element methods to the frequency response analysis, the conventional methods are known to give unstable and inaccurate results near the natural frequencies. To address this issue, a new sensitivity based stabilized formulation for stochastic frequency response analysis is proposed in this paper. The main difference over the conventional spectral methods is that the polynomials of random variables are applied to both numerator and denominator in approximating the harmonic response solution. In order to reflect the resonance behavior of the structure, the denominator polynomials is constructed by utilizing the natural frequency sensitivity and the random mode superposition. The numerator is approximated by applying a polynomial chaos expansion, and its coefficients are obtained through the Galerkin or the spectral projection method. Through various numerical studies, it is seen that the proposed method improves accuracy, especially in the vicinities of structural natural frequencies compared to conventional spectral methods.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.142-147
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• 2001

Natural convection of a magnetic fluid is different from that of Newtonian fluids because magnetic body force exists in an addition to gravity and buoyancy. In this paper, natural convection of a magnetic fluids(W-40) in a cubic cavity is examined by numerical and experimental method. One side wall was kept at a constant temperature($25^{\circ}C$), and the opposite side wall was also held at a constant but lower temperature($20^{\circ}C$). Under above conditions, various magnitudes of the magnetic fields were applied up. GSMAC scheme is used for a numerical method, and the thermo-sensitive liquid crystal film(R20C5A) is utilized in order to visualize wall-temperature distributions as an experimental method. This study has resulted in the following fact that the natural convection of a magnetic fluids is controlled by the direction and intensity of the magnetic fields.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.1
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• pp.63-69
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• 2013

In order to find the optimum design of structures that have characteristic natural frequency range, a numerical optimization method to solving eigenvalue problems is a widely used approach. However in the most cases, it is difficult to decide the accurate thickness and shape of structures that have allowable natural frequency in design constraints. Parallel analysis algorithm involving the feasible direction optimization method and Rayleigh-Ritz eigenvalue solving method is developed. The method is implemented by using finite element method. It calculates the optimal thickness and the thickness ratio of individual elements of the 2-D plane element through a parallel algorithm method which satisfy the design constraint of natural frequency. As a result this method of optimization for natural frequency by using finite element method can determine the optimal size or its ratio of geometrically complicated shape and large scale structure.