• International journal of advanced smart convergence
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• v.4 no.2
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• pp.29-33
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• 2015

In this paper, we propose the method to improve the performance of the antenna system that contains three bands, such as Lte3G, WLAN and Lte4G. This antenna has an advantage that can cover the three different frequency bands 2.1GHz, 2.4GHz and 2.6GHz through one antenna design. The design and simulations are done using CST Microwave Studio 2014 program. The antenna is designed by using the FR-4 (lossy) substrate with the dielectric constant of er=4.3 and dielectric loss tangent 0.025. The substrate dimensions are the following; Thickness[h] is 1.6mm, Length is 90mm, and Width is 40mm. The ground is designed by using the PEC material with h=0.035mm. The patch is designed by using the copper with h=0.035mm. In the near future, we will fabricate the antenna, which we have designed, and then apply this antenna to the mobile communication system. And we will test this mobile communication system for the diverse environments.

• Korean Journal of Plant Resources
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• v.25 no.5
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• pp.652-655
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• 2012

'Blue Edge' (Hosta minor) was induced by ethyle methane sulfonate (EMS) to obtain mutants. Among induced leaf variegated hosta plants, some with deep-green color pattern on the edge of the leaves was selected. They were cultivated via vegetative propagation. Assessment of botanical characteristics was conducted for three years since 2003. The major characteristic of these cultivars is that they maintain their deep-green color on the edge of the leaves all year round. These cultivars are useful as materials for pot plant or as ground cover plant.

• Korean Journal of Plant Resources
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• v.25 no.4
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• pp.504-506
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• 2012

Hosta 'Yellow Tiara' was induced using methyle methane sulfonate (MMS) to obtain mutagens. Among the induced leaf-variegated hosta plants, some with yellow-green leaves were selected. They were cultivated via vegetative propagation. Assessment of the botanical characteristics was conducted for three years since 2004. The major characteristic of these cultivars is that they maintain their yellow-green leaves uniformly all year round. These cultivars are useful as materials for pot plants or as ground cover.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.434-437
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• 2006

Though numerous drilling has been performed in Jeju Island for development of ground water, the wells are mostly located along the coast lines or at low altitude area, and can hardly be found on the mid-mountain area. Two-dimensional magnetotelluric (MT) surveys have been carried out to cover the lack of geological Informal ion on the mid-mountain area and to figure out any possible structures or evidences for deep geothermal energy remained. Two-dimensional (2-D) inversion of MT data for four survey lines surrounding the Halla mountain show a thick layer having around 10 ohm-m in the depth of a few hundred meters throughout the survey area, which can be considered as the unconsol idated sedimentary layer. And they also show a conductive anomaly extending to more than 2km depth at the central part of each survey lines, which can possibly be related with old volcanic activities during the formation of Halla Mt.. Further seological/geophysical investigations should be followed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.573-576
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• 2005

This research presents a three-dimensional modeling technique for a flexible sheet. A relative coordinate formulation is used to represent the kinematics of the sheet. The three-dimensional flexible sheet is modeled by multi-rigid bodies interconnected by out-of-plane joints and plate force elements. A parent node is designated as a master body and is connected to the ground by a floating joint to cover the rigid motion of the flexible sheet in space. Since the in-plane deformation of a sheet such as a paper and a film is relatively small, compared to out-of-plane deformation, only the out-of-plane deformation is accounted for in this research. The recursive formulation has been adopted to solve the equations of motion efficiently. An example is presented to show the validity of the proposed method.

• Nuclear Engineering and Technology
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• v.51 no.3
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• pp.894-903
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• 2019

An approach for collapse risk assessment is proposed to evaluate the vulnerability of electric cabinet in nuclear power plants. The lognormal approaches, namely maximum likelihood estimation and linear regression, are introduced to establish the fragility curves. These two fragility analyses are applied for the numerical models of cabinets considering various boundary conditions, which are expressed by representing restrained and anchored models at the base. The models have been built and verified using the system identification (SI) technique. The fundamental frequency of the electric cabinet is sensitive because of many attached devices. To bypass this complex problem, the average spectral acceleration $S_{\bar{a}}$ in the range of period that cover the first mode period is chosen as an intensity measure on the fragility function. The nonlinear time history analyses for cabinet are conducted using a suite of 40 ground motions. The obtained curves with different approaches are compared, and the variability of risk assessment is evaluated for restrained and anchored models. The fragility curves obtained for anchored model are found to be closer each other, compared to the fragility curves for restrained model. It is also found that the support boundary conditions played a significant role in acceleration response of cabinet.

• Korean Journal of Agricultural Science
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• v.48 no.3
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• pp.465-471
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• 2021

Grass breeding starts with the process of selecting grass with good traits, and this operation consumes a lot of resources. Therefore, there is a need for an efficient screening method. Stolon is a unit for the storage of carbohydrates and vegetative propagation, which enhances grass growth and grass sod. Grass varieties with active production of stolons have excellent traits because they reproduce quickly and have a high density. To select grass with such a trait, the survival rate and the production rate of stolon after transplantation of 72 grass germplasms were investigated. After transplantation, the survival rate ranged from 75% to 100%. The majority of the grass cultivars showed a 100% survival rate. Therefore, the group was divided into two groups: A grass variety showing 100% survival and a grass variety that did not show 100% survival. The grass cultivar group, which showed a 100% survival rate after transplantation, included 61 turf varieties, and the rates of stolon production in these grass varieties ranged from 0 to 100%. In contrast, 10 varieties were included in the grass cultivar group that did not show 100% survival after transplantation. These cultivars had a stolon production rate of 0 to 33%. The results suggest that grass germplasms with a 100% survival rate should be selected.

• Nuclear Engineering and Technology
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• v.54 no.3
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• pp.926-939
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• 2022

The area of this study will cover the location-wise seismic response variation of an electrical cabinet in nuclear power point (NPP) based on classical reliability analysis. The location-based seismic ground motion (GM) selection is carried out with the help of probabilistic seismic hazard analysis using PSHRisktool, where the variation of reliability analysis can be understood from the relation between the reliability index and intensity measure. Two different approaches such as the first-order second moment method (FOSM) and Monte Carlo Simulation (MCS) are helped to evaluate and compare the reliability assessment of the cabinet. The cabinet is modeled with material uncertainty utilizing Steel01 as the material model and the fiber section modeling approach is considered to characterize the section's nonlinear reaction behavior. To verify the modal frequency, this study compares the FEM result with recorded data using Least-Squares Complex Exponential (LSCE) method from the impact hammer test. In spite of a few investigations, the main novelty of this study is to introduce the reader to check and compare the seismic reliability assessment variation in different seismic locations and for different earthquake levels. Alongside, the betterment can be found by comparing the result between two considered reliability estimation methods.

• Structural Engineering and Mechanics
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• v.83 no.1
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• pp.45-51
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• 2022

The need to account for accidental torsion in seismic design is no longer debatable, however, the seismic codes' requirement for accidental eccentricity has recently faced criticism. In order to get as close to real conditions as possible, this study investigated the impact of accidental torsion in symmetric RC multistory buildings caused by one of its many sources, the torsional earthquake component, and compared the results to those obtained by using the accidental eccentricity recommended by the codes (shifting the center of mass). To cover a wide range of frequencies and site conditions, two types of torsion seismic components were used: a recorded torsion accelerogram and five others generated using translation accelerograms. The main parameters that govern seismic responses, such as the number of stories (to account for the influence of all modes of vibration) and the frequency ratio (Ω) variation, were studied in terms of inter-story drift and displacement responses, as well as torsional moment. The results show that the eccentricity ratio of 5% required by most codes for accidental torsion should be reexamined and that it is prudent for computer analysis to use the static moment approach to implement the accidental eccentricity while waiting for new seismic code recommendations on the subject.

• Journal of Environmental Science International
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• v.31 no.6
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• pp.471-477
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• 2022

This field experiment aimed to identify the optimal planting density for establishing a management plan for ground-cover plants under roadside trees. Liriope platyphylla and Hosta longipes both widely used for planting under trees were selected as the plant materials and planted under Prunus serrulata var. spontanea at different planting densities. Based on the distance between each plant, 4 planting densities were used: 11%, 25%, 49%, and 83% with three replications. To estimate plant growth, plant height, number of leaves and tillers, fresh and dry weight, and visual quality were investigated. Liriope platyphylla exhibited relatively better growth at the highest planting density of 83%. For Hosta longipes, however, the lower growth was positively correlated with high planting density. Therefore, the optimal planting density for Liriope platyphylla is 83% and for Hosta longipes is 11%.