• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.6
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• pp.1033-1043
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• 1997

In order to understand the generation mechanism of the Ulleung Eddy, we carried out a series of numerical experiments using the nonlinear 11/2 - layer model allowing the inflow of the Tsushima Current. According to our numerical results, the Ulleung Eddy was generated due to the inflow variations of the Tsushima Current. Its inflow through the Korea Strait was deflected to the east due to the Coriolis force and the nonlinear self advection. Thus, an anticyclonic motion was formed at the north of the Korea Strait. The inflow became a coastal boundary current, and finally flowed out model ocean through the eastern exit. When the speed of inflow decreased slowly, the eddy- like motion at the north of the Korea Strait changed into an enclosed anticyclonic eddy of about 200 km in diameter. The Ulleung Eddy became circular shape due to the nonlinear self advection, then changed into elliptical shape in meridional direction because of the blocking effect of the western boundary.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.6
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• pp.1044-1055
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• 1997

To find out generating mechanism of eddies in the polar frontal zone of the East Sea, we carried out a series of numerical experiments using the nonlinear $1^{1/2}-layer$ model allowing the effect of the polar front. We assumed the polar front at about $39^{\circ}N$ in zonal direction with the cold water region in the northern part and the warm water region in the southern part of the model ocean. To examine the effect of the frontal motion without the influence of the Tsushima Current from the beginning of the geostrophic adjustment, the initial state of the model ocean was assumed motionless. Eastward current was caused by the geostrophic adjustment process in the polar frontal zone that induced a steady northward coastal current along the Korean coast to satisfy the mass continuity. The overshooting of this coastal current acted as an initial disturbance of the zonal flow field which caused meanders and eddies. The spatial scales of eddies were in good agreement with the baroclinic instability theory.

• Advances in concrete construction
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• v.3 no.2
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• pp.91-102
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• 2015

In this paper, the load-deflection analysis of the Carbon Fiber Reinforced Polymer (CFRP) strengthened Reinforced Concrete (RC) slab using Recurrent Neural Network (RNN) is investigated. Six reinforced concrete slabs having dimension $1800{\times}400{\times}120mm$ with similar steel bar of 2T10 and strengthened using different length and width of CFRP were tested and compared with similar samples without CFRP. The experimental load-deflection results were normalized and then uploaded in MATLAB software. Loading, CFRP length and width were as neurons in input layer and mid-span deflection was as neuron in output layer. The network was generated using feed-forward network and a internal nonlinear condition space model to memorize the input data while training process. From 122 load-deflection data, 111 data utilized for network generation and 11 data for the network testing. The results of model on the testing stage showed that the generated RNN predicted the load-deflection analysis of the slabs in acceptable technique with a correlation of determination of 0.99. The ratio between predicted deflection by RNN and experimental output was in the range of 0.99 to 1.11.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.11
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• pp.81-87
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• 2000

A new resonator that is fabricated by single polysilicon layer process is presented. The resonator can move in two orthogonal direction on the plane parallel to the substrate. And the resonant frequencies of the two modes are intrinsically designed to be identical since the overall structure of the resonator is symmetric about the two directions of motion. Since the resonator ideally has two identical vibration mode, it can be applied to various micro-devices that requires multi DOF motion, especially to microgyroscopes. To investigate the feasibility of application of the resonator, dynamic model of the resonator including the nonlinear behavior of driving electrodes is derived and evaluated with the fabricated one, and the self-tuning characteristics are proved though experiments.

• Journal of the Korean Geotechnical Society
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• v.34 no.11
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• pp.57-70
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• 2018

In this study, verification of the nonlinear effective stress analysis is performed for introducing performance based earthquake resistance design of port and harbor structures. Seismic response of gravitational caisson quay wall in numerical analysis is compared directly with dynamic centrifuge test results in prototype scale. Inside of the rigid box, model of the gravitational quay wall is placed above the saturated sand layer which can show the increase of excess pore water pressure. The model represents caisson quay wall with a height of 10 m, width of 6 m under centrifugal acceleration of 60 g. The numerical model is made in the same dimension with the prototype scale of the test in two dimensional plane strain condition. Byrne's liquefaction model is adopted together with a nonlinear constitutive model. Interface element is used for sliding and tensional separation between quay wall and the adjacent soils. Verification results show good agreement for permanent displacement of the quay wall, horizontal acceleration at quay wall and soil layer, and excess pore water pressure increment beneath the quay wall foundation.

• Advances in concrete construction
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• v.2 no.2
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• pp.91-108
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• 2014

This paper presents a nonlinear finite element analysis (FEA) in order to investigate the flexural performance of one-way slabs strengthened by epoxy-bonded steel plates. Four point loading scheme is selectively chosen. A model is developed to implement the material constitutive relationships and non-linearity. Five Slabs were modeled in FEM software using ABAQUS. One slab was unstrengthened control slab and the others were strengthened with steel plates with varying the plate thickness and configuration. In order to verify the accuracy of the numerical model, a comparison was done between the experimental results available in the literature and the proposed equations by ACI 318-11 for the calculation of ultimate load capacities of strengthened slabs, the agreement has proven to be good and FEA attained accurate results compared with ACI code. A parametric study was also carried out to investigate the influence of thickness of steel plate, strength of epoxy layer and type of strengthening plate on the performance of plated slabs. Also, the practical and technical feasibility of splitting the steel plate in strengthening process has been taken into account. For practical use, the author recommended to use bonded steel plate as one unit rather than splitting it to parts, because this saves more effort and reduces the risk of execution errors as in the case of multiple bonded parts. Both techniques have nearly the same effect upon the performance of strengthened slabs.

• Journal of the Earthquake Engineering Society of Korea
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• v.11 no.1 s.53
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• pp.67-77
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• 2007

Site coefficients in IBC and KBC codes have some limits to predict the rational seismic responses of a structure, because they take into account only the effect of the soil amplification without the effects of the structure-soil interaction. In this study, upper and lower limits of the site coefficients are estimated through the pseudo 3-D elastic seismic response analyses of structures built on the linear or nonlinear soil layers taking Into account the effects of the structure-soil interaction. Soil characteristics of site classes of A, B and C were assumed to be linear, and those of site classes of D and E were done to be nonlinear and the Ramberg-Osgood model was used to evaluate shear modulus and damping ratio of a soil layer depending on the shear wave velocity of the soil layer, Seismic analyses were performed with 12 weak or moderate earthquake records scaled the peak acceleration to 0.1g or 0.2g and deconvoluted as earthquake records at the bedrock located at 30m deep under the outcrop. With the study results of the elastic seismic response analyses of structures, new standard response spectrum and upper and lower limits of the site coefficients of $F_{a}\;and\;F_{v}$ at the short period range and the period of 1 second are suggested including the effects of the structure-soil interaction, and new site coefficients for the KBC code are also suggested.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.5A
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• pp.490-496
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• 2007

This paper describes the design and implementation of an integrated LTCC front-end module for the IEEE802.11a WLAN applications by performing the behavioral-level simulation using measurement-based behavioral model. To meet the IEEE802.11a WLAN standard, a system transmitting 1024 symbols through 64-QAM process at the rate of 54Mbps should be implemented and nonlinear properties are confirmed by simulations of ACPR and EVM in this circumstance. The right offsets of ACPR which are 30MHz, 20MHz, and 11MHz distant from the center frequency of 5.8GHz are 49.36dBc, 36.90dBc, and 24.58dBc, respectively. The left offsets are 50.14dBc, 30.04dBc, and 28.85dBc, respectively and EVM is 2.94%. The size of the module implemented with LTCC five-layer substrates is $13.4mm{\times}14.2mm$. The measured characteristics of the transmitter show P1dB of 16.2dBm and power gain of 16.73dB. Those of the receiver exhibit the small signal gain of 16.24dB and noise figure of 7.83dB.

• Magazine of the Korean Society of Agricultural Engineers
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• v.39 no.4
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• pp.106-113
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• 1997

Dynamic loading of structures often causes excursions of stresses well into the inelastic range, and the influence of the geometric changes on the dynamic response is also significant in many cases. Therefore, both material and geometric nonlinearity effects should be considered in case that a dynamic load acts on the structure. A structure in a nuclear power plant is a structure of importance which puts emphasis on safety. A nuclear container is a pressure vessel subject to internal pressure and this structure is constructed by a reinforced concrete or a pre-stressed concrete. In this study, the material nonlinearity effect on the dynamic response is formulated by the elasto-viscoplastic model highly corresponding to the real behavior of the material. Also, the geometrically nonlinear behavior is taken into account using a total Lagrangian coordinate system, and the equilibrium equation of motion is numerically solved by a central difference scheme. The constitutive relation of concrete is modeled according to a Drucker-Prager yield criterion in compression. The reinforcing bars are modeled by a smeared layer at the location of reinforcements, and the steel layer model under Von Mises yield criteria is adopted to represent an elastic-plastic behavior. To investigate the dynamic response of a nuclear reinforced concrete containment structure, the steel-ratios of 0, 3, 5 and 10 percent, are considered. The results obtained from the analysis of an example were summarized as follows 1. As the steel-ratio increases, the amplitude and the period of the vertical displacements in apex of dome decreased. The Dynamic Magnification Factor(DMF) was some larger than that of the structure without steel. However, the regular trend was not found in the values of DMF. 2. The dynamic response of the vertical displacement and the radial displacement in the dome-wall junction were shown that the period of displacement in initial step decreased with the steel-ratio increases. Especially, the effect of the steel on the dynamic response of radial displacement disapeared almost. The values of DMF were 1.94, 2.5, 2.62 and 2.66, and the values increased with the steel-ratio. 3. The characteristics of the dynamic response of radial displacement in the mid-wall were similar to that of dome-wall junction. The values of DMF were 1.91, 2.11, 2.13 and 2.18, and the values increased with the steel-ratio. 4. The amplitude and the period of the hoop-stresses in the dome, the dome-wall junction, and the mid-wall were shown the decreased trend with the steel-ratio. The values of DMF were some larger than those of the structure without steel. However, the regular trend was not found in the values of DMF.

• Journal of Korean Ophthalmic Optics Society
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• v.7 no.2
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• pp.1-11
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• 2002

A mathematical model is proposed to analyze the force; acting on the hard contact lens fitted on the cornea. The model incorporates the nonlinear equations and their numerical solution program, based on the formulations of surface tension force arising from the capillary action in the tear-film layer between the lens and cornea. The model simulates how the adhesion between lens and cornea varies according to the base curves and diameters of the lenses. When the spherical lens is fitted on the spherical cornea it is to rotate downward due to the weight of lens itself until it reaches an equilibrium position along the cornea where the counter(upward) moment caused by net force between the upper and lower portion of the periphery of lens. It is found that both the adhesion and displacement of lens along the cornea, where the gravity of lens balances the capillary-induced upward force, increases rapidly as the base curve of lens increases, i.e., as the lens gets flatter, while the increase in the diameter of lenses has resulted in the less increase in the rotation and adhesion. With the base curve and diameters of lenses being remained constant the increase in surface tension of tear film yields the increase in the adhesion between the cornea and lens while the initial rotation of lens is inversely proportional to the surface tension of the tear film.