• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.40 no.5
• /
• pp.938-943
• /
• 2015

The proposed circular patch antenna was designed to include relative bandwidth of above 25% as designed by the FCC in the FCC in the 3.1 ~ 10.6 GHz band. The antenna was induced to have a wide band characteristic through two structures of the usual microstrip line and a microstrip line with a linear change in impedance. The proposed finally antenna was designed using an FR4_epoxy substrate with 4.7% permittivity, 0.02 of loss tangent, and 1.6 mm of thickness, and was simulated with the use of HFSS made by Ansys. Return loss at frequency, VSWR, radiation pattern and the gain of the antenna were analysed. As a result, if satisfied a return loss of -10 dB and $VSWR{\leq}2$ from 2.28 ~ 13.35 GHz, showing about the bandwidth of 11.89 GHz, and the radiation pattern was unidirectional in all bands. The antenna gain gradually increased from 2 ~ 8 GHz and had the highest gain of 7.92 dBi at 8 GHz. and the gain gradually decreased in the 9 ~ 12 GHz band.

• Asian-Australasian Journal of Animal Sciences
• /
• v.20 no.1
• /
• pp.82-88
• /
• 2007

Two experiments were conducted to see the effects of lacquer meal (Rhus verniciflua) on layer performance. In Exp. 1, seventy-two Hy-Line brown layers, 46 wk of age were fed 0, 1.5% and 3.0% lacquer added diets for 6 weeks. Diets contained 2,650 kcal/kg ME and 16.50% CP. In Exp. 2, high-energy diets were fed to 72 Hy-line brown layers of 46 wk age for 6 wk. The diets were: control (3,000 kcal/kg ME and 16.50% CP); T1 and T2 contained 1.5 and 3.0% lacquer respectively, in addition to high energy levels. Each treatment had four replicates with 6 birds each in both the experiments. During Exp.1, there was no effect on average daily feed intake, egg production and feed efficiency, however, egg weight was linearly (p=0.0128) decreased with the addition of lacquer in diets. The egg quality parameters measured at bi-weekly intervals did not reveal any particular trend. In Exp 2., high-energy diets have decreased the feed intake and egg production in all groups. However, feeding lacquer at 1.5% increased the egg production by 9% than control. The yolk fat content was increased due to treatments showing quadratic trend (p=0.0683). The liver fat content was decreased by 40-43% than control in lacquer added diets. Except palmitic, oleic and arachidonic acids, some yolk fatty acids showed a linear decreasing trend in lacquer diets. The serum triglycerides and total cholesterol levels were not influenced with lacquer in the diets; however, the serum glucose level was linearly decreased with the addition of lacquer. In conclusion, lacquer meal supplementation significantly affected the performance of layers fed high-energy diets.

• The Korean Journal of Applied Statistics
• /
• v.14 no.1
• /
• pp.71-80
• /
• 2001

Logistic regression model is one of the most popular linear models for a binary response variable and used for the estimation of probability function. In many practical situations, the probability function can be expressed by a bell shaped curve and such a function can be estimated by a second order logistic regression model. However, when the probability curve is asymmetric, the estimation results using a second order logistic regression model may not be precise because a second order logistic regression model is a symmetric function. In addition, even if a second order logistic regression model is used, the interpretation for the effect of second order term may not be easy. In this paper, in order to alleviate such problems, an estimation method for asymmetric probabiity curve based on a first order logistic regression model and iterative bi-section method is proposed and its performance is compared with that of a second order logistic regression model by a simulation study.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2010.09a
• /
• pp.349-356
• /
• 2010

In this study, a new design method of pile bent structure considering plastic hinge was proposed on the basis of the beam-column model. Based on the analysis results, it is found that the positioning of plastic hinge on the pile bent structure was influenced by nonlinear behavior of material and p-$\Delta$ effect. Moreover, concrete cracking began to occur at the joint section between the pile and column in case of pile bent structure with different cross-sections. The plastic hinge can be developed on the pile bent structure when large displacement was occurred, and pile bent structures can be maintained well only if it is developed on the column part. Therefore, in this study, the optimized cross-section ratio between column and pile was analyzed to induce the plastic hinge at the joint section between the pile and column. Based on this, the optimized diameter ratio of pile and column can be obtained below the inflection point of the bi-linear curve depending on the relations between column-pile diameter ratio($D_c/D_p$) and normalized lateral cracking load ratio($F/F_{Dc=Dp}$). And through this study, it is founded that in-depth limit($L_{As}$=0.4%) normalized by the pile length($L_P$) are proportionally decreased as the pile length($L_P/D_P$) increases up to $L_P/D_P$=17.5, and beyond that in-depth limit converges to a constant value. Finally, it is found that the proposed limit depth by taking into account the minimum concrete-steel ratio would be more economical design of the pile bent structure.

• KIEAE Journal
• /
• v.16 no.1
• /
• pp.81-87
• /
• 2016

Purpose: Heat transfers phenomena are described by the second order partial differential equation and its boundary conditions. In a three-dimensional structure of a building, the heat transfer phenomena generally include more than one material, and thus, become complicate. The analytic solutions are useful to understand heat transfer phenomena, but they can hardly be applied in engineering or design problems. Engineers and designers have generally been forced to use numerical methods providing reliable results. Finite volume methods with the unstructured grid system is only the suitable means of the analysis for the complex and arbitrary domains. Method: To obtain an numerical solution, a discretization method, which approximates the differential equations, and the interpolation methods for temperature and heat flux between two or more materials are required. The discretization methods are applied to small domains in space and time, and these numerical solutions form the descretized equations provide approximated solutions in both space and time. The accuracy of numerical solutions is dependent on the quality of discretizations and size of cells used. The higher accuracy, the higher numerical resources are required. The balance between the accuracy and difficulty of the numerical methods is critical for the success of the numerical analysis. A simple and easy interpolation methods among multiple materials are developed. The linear equations are solved with the BiCGSTAB being a effective matrix solver. Result: This study provides an overview of discretization methods, boundary interface, and matrix solver for the 3-dimensional numerical heat transfer including two materials.

• Journal of the Korean Wood Science and Technology
• /
• v.42 no.4
• /
• pp.367-375
• /
• 2014

A simplified material model, which was efficiently implemented in a three-dimensional finite solid element (3D FE) analysis for wood was developed. The bi-linear elasto-plastic anisotropic material theory was adopted to describe constitutive relations of wood in three major directions including longitudinal, radial and tangential direction. The assumption of transverse isotropy was made to reduce the requisite 27 material constants to 6 independent constants including elastic moduli, yield stresses and Poisson's ratios in the parallel, and perpendicular to grain directions. The results of Douglas fir compression tests in the three directions were compared to the 3D FE simulation incorporated with the wood material model developed in this study. Successful agreements of the results were found in the load-deformation curves and the permanent deformations. Future works and difficulties expected in the advanced application of the model were discussed.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.3 no.1
• /
• pp.1-8
• /
• 1999

Dynamic elastoplastic LPM (lumped parameter mass) analyses are carried out in order to investigate the seismic resistant performance of a typical high-rise shear wall apartment subjected to several earthquakes. Three-dimensional nonlinear pushover analysis is adopted to estimate initial elastic stiffness, yielding strength and post-yielding stiffness of each story for the time history analysis of LPM shear model. For the hysteresis of each story, Clough and bilinear models are used with the input of four recorded earthquake ground motions of EI Centro 1940 NS, Taft 1952 EW, Hachinohe 1968 NS and Kobe 1995 NS, of which the amplitudes are scaled down to have the same maximum ground velocity of 12 kine. The result shows that yieldings take place in most storys of the building, i.e. the earthquake resistant capacity of this high-rise shear wall apartment is not sufficient at the event of earthquake M=5~6.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.22 no.2
• /
• pp.45-54
• /
• 2018

The seismically isolated nuclear power plants shall be designed for design basis earthquake (DBE) and considered to ensure safety against beyond design basis earthquake (BDBE). In order to limit the excessive displacement of the seismic isolation system of the seismically isolated structure, the moat is installed at a certain distance from the upper mat supporting the superstructure. This certain distance is called clearance to stop (CS) and is calculated from the 90th percentile displacement of seismic isolation system subjected to BDBE. For design purposes, the CS can be obtained simply by multiplying the median displacement of the seismic isolation system against DBE by scale factor with a value of 3. The DBE and BDBE used in this study were generated by using 30 sets of artificial earthquakes corresponding to the nuclear standard design spectrum. In addition, latin hyper cube sampling was applied to generate 30 sets of artificial earthquakes corresponding to maximum - minimum spectra. For the DBE, the median displacement and the 99th percentile displacement of the seismic isolation system were calculated. For the BDBE, the suitability of the scale factor was assessed after calculating the 90th percentile displacement of the seismic isolation system.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.18 no.5
• /
• pp.469-485
• /
• 2016

The failure of rock mass around deep tunnel, different from shallow tunnel largely affected by discontinuities, is dominated by magnitudes and directions of stresses, and the failures dominated by stresses can be divided into ductile and brittle features according to the conditions of stresses and the characteristics of rock mass. It is important to know the range and the depth of the V-shaped notch type failure resulted from the brittle failure, such as spalling, slabbing and rock burst, because they are the main factors for the design of excavation and support of deep tunnels. The main features of brittle failure are that it consists of cohesion loss and friction mobilization according to the stress condition, and is progressive. In this paper, a three-dimensional numerical model has been developed in order to simulate the brittle behavior of rock mass around deep tunnel by introducing the bi-linear failure envelope cut off, elastic-elastoplastic coupling and gradual spread of elastoplastic regions. By performing a series of numerical analyses, it is shown that the depths of failure estimated by this model coincide with an empirical relation from a case study.

• Elastomers and Composites
• /
• v.43 no.3
• /
• pp.173-182
• /
• 2008

Rubber-pad forming process for materials such as metal in which portions of the die which act upon the material is composed of a natural or synthetic rubber or elastomer material. This makes the rubber pad forming process relatively cheap and flexible, high accuracy for small product series in particular. In this study, we carried out the physical test and finite element analysis of elastomer such as natural rubber and urethane for steel rack rube forming. The non-linear property of elastomer which are described as strain energy function are important parameter to design and evaluate of elastomer component. These are determined by material tests which are uni-axial tension and bi-axial tension. This study is concerned with simulation and investigation of the significant parameters associated with this process.