• Journal of the Korean Geotechnical Society
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• v.34 no.11
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• pp.5-19
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• 2018

The characteristics of the skin shear stress distribution for the fixed length of the ground anchor are extremely nonlinear and the engineering mechanisms are complex relatively. So it is difficult to design the anchors simulating the actual behavior by considering various soil conditions and nonlinear behavior. Due to these limits, constant skin shear stress distributions for the whole fixed length of the ground anchor are usually assumed in the design for the sake of convenience. In this study, to assess the pull-out behavior of the tension-type ground anchors, the in-situ pull-out tests in weathered-soil conditions were carried out. Based on the test results, the skin shear behaviors for the fixed length of tension-type ground anchors were established and the multi-linear slip shear model predicting this behavior and an analytical technique applying this model were proposed. From the similarity between the results of the in-situ pull-out tests and those of the analytical technique, the applicability and availability of the multi-linear slip shear model and the proposed analytical technique were verified. The maximum shear stress was developed at the start point of the fixed length acting with the smaller load than the maximum pull-out load but the minimum shear stress was developed at the start point of the fixed length and the maximum shear stress was developed at the point apart from the start point of the fixed length after the maximum pull-out load.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.9
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• pp.969-974
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• 2011

A carbon nanotube (CNT) is a cylindrical carbon nanostructure with good transport properties along the tube's axis. As an approach for realizing the practical use of CNTs, CNT networks are fabricated and their applications in many fields are investigated. To fabricate thin CNT-based films, several methods have been proposed and used. Among these methods, the spray coating method is a robust method for fabricating a large area. However, it is difficult to achieve uniformity in the CNT network. To solve this problem, it is necessary to understand the effect of the sprayprocess parameters on the deposition thickness distribution. In this study, a numerical model for predicting the deposition thickness distribution during the spray process was developed. The spatial deposition thickness distributions obtained according to various nozzle paths were analyzed using the developed numerical model.

• Water for future
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• v.10 no.1
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• pp.79-94
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• 1977

This study is aimed at the establishment and examination of stochastic model to simulate Run-length and Run-sum of daily rainfall and streamflow. In the analysis, daily rainfall records in major cities (Seoul, Kangnung, Taegu, Kwangju, Busan, and Cheju) and daily streamflow records of Major rivers (Han, Nakdong and Geum River) were used. Also, the fitness of daily rainfall and streamflow to Weibull and one parameter exponential distribution was tested by Chi-square and Kolmogorov-Smirnov test, from which it was found that daily rainfall and streamflow generally fit well to exponential type distribution function. The Run-length and Run-sum were simulated by the Weibull Model (WBL Model), one parameter exponential model (EXP-1 Model) based on the Nonte Carlo technique. In this result, Run-length of rainfall was fitted for one parameter exponential model and Run-length of streamflow was fitted for Weibull model. And Run-sum of rainfall and streamflow were fit comparatively for regression model. Hereby, statistical charactristics of Simulation data were sinilar to historical data.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.2
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• pp.214-219
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• 2016

The grating is the main purpose of drainage in civil engineering, architecture. This study examined the change and stress distribution by simulating three models of Vertical type grating structures that reduced the resistibility in respect of velocity rather than horizontal type grating and to design a grating with the optimal grating gap. The vertical type and horizontal type grating were compared in terms of the maximum stress and strain to identify the better product.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.7
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• pp.732-739
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• 2002

Performance of the applicator for hyperthermia is determined by both the degree of impedance matching and specific absorption rate(SAR) distribution in the surrounding tissue. In this paper, the coaxial-slot antenna using staircasing approximation in the FDTD is analyzed and the coaxial-slot antenna for the hyperthermia improving heating characteristics is designed. The SAR of the coaxial-slot antenna approximated to staircasing and square model is analyzed, and the SAR of staircasing model is compared with Saito's SAR measurement and square model. As a result, the SAR of proposed model exhibited agreement with the Saito's measurement of square model. Ig averaged SAR on the liver caused by proposed antenna in this paper is 195 W/kg, and is about 27.9 % higher than the Saito's antenna 152.5 W/kg, respectively.

• Journal of the Korean Vacuum Society
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• v.20 no.3
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• pp.165-175
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• 2011

This paper introduces statistical features observed from measured batch data from the multiple operation state variables of dry vacuum pumps running in the semiconductor processes. The amplitude distribution characteristics of such state variables as inlet pressures, supply currents of the booster and dry pumps, and exhaust pressures are shown to be divided into two or three distinctive regions. This observation gives an idea of using an adaptive parametric model (APM) chosen to describe their statistical features. This modelling, in comparison to the traditional dynamic time wrapping algorithm, is shown to provide superior performance in computation time and memory resources required in the preprocessing stage of sampled batch data for the diagnosis of running dry vacuum pumps. APM model-based batch data are demonstrated to be very appropriate for monitoring and diagnosing the running conditions of dry vacuum pumps.

• Journal of the Korean earth science society
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• v.28 no.7
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• pp.878-890
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• 2007

This study aimed to provide a fundamental basis for the development and promotion of a Korea windchill temperature index model in the field of human biometeorology. For this, a sensitivity model currently being used by KMA (Korea Meteorological Administration) was analyzed. The results of the analysis showed that the Korean peninsula could be divided into the urban area, the coastal/island area, the inland area, and the mountain area. The average temperature was highest in the coastal/island area, while it was lowest in the mountain regions. The lowest temperature in the urban and coastal/island areas was 20 degrees below zero and that in the inland and mountain regions were 30 degrees below zero. As for wind speed, both average and maximum wind speed were highest in the coastal/island area. The distribution of temperature and wind speed in winter was similar to that of the entire period. The results of the JAG/Tl and Missenard model sensitivity showed that temperature tends to have more influence on sensitivity than any other factors. In sub-zero temperature, however, the influence of wind speed tends to increase.

• Nuclear Engineering and Technology
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• v.25 no.1
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• pp.154-165
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• 1993

A stochastic method using continuous time Markov process is presented to model the one-dimensional convective nuclide transport in geologic media, which have usually heterogeneous feature in physical/geochemical parameters such as velocity, dispersion coefficient, and retardation factor resulting poor description by conventional deterministic advection-dispersion model. The primary desired quantities from a stochastic model are the mean values and variance of the state variables as a function of time. The time-dependent probability distributions of nuclides are presented for each discretized compartment given the volumetric groundwater flux and the intensity of transition. Since this model is discrete in medium space, physical/geochemical parameters which affect nuclide transport can be easily incorporated for the heterogeneous media as well as remarkably layered media having spatially varied parameters. Even though the Markov process model developed in this study was shown to be sensitive to the number of discretized compartments showing numerical dispersion as the number of compartments are increased, this could be easily calibrated by comparing with the analytical deterministic model.

• Korean Journal of Environment and Ecology
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• v.37 no.6
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• pp.450-463
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• 2023

The objective of this study is to derive the core habitat of the Kirengeshoma koreana Nakai utilizing Habitat Suitability Index (HSI) and Maximum Entropy (MaxEnt) models. Expert-based models have been criticized for their subjective criteria, while statistical models face difficulties in on-site validation and integration of expert opinions. To address these limitations, both models were employed, and their outcomes were overlaid to derive the core habitat. Five variables were identified through a comprehensive literature review and spatial analysis based on appearance coordinates. The environmental variables encompass vegetation zone, forest type, crown density, annual precipitation, and effective soil depth. Through surveys involving six experts, importance rankings and SI (Suitability Index) scores were established for each variable, subsequently facilitating the creation of an HSI map. Using the same variables, the MaxEnt model was also executed, resulting in a corresponding map, which was merged to construct the definitive core habitat map. Out of 16 observed locations of K. koreana, 15 were situated within the identified core habitat. Furthermore, an area historically known to host K. koreana but not verified in the present, Mt. Yeongchwi, was found to lack a core habitat. These findings suggest that the developed models exhibit a high degree of accuracy and effectively reflect the current ecological landscape.

• The Journal of the Acoustical Society of Korea
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• v.18 no.4
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• pp.65-70
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• 1999

To examine the space variances of the sound pressure level for five different types (normal frequency spacing) of reverberation rooms, simulations were conducted using the Finite Element Method. In case of infinite surface impedance, nonrectangular reverberation rooms showed small Standard Deviations across the band of frequency, and in case of finite surface impedance, ideal rectangular reverberation rooms showed the similar results as those in irregular shaped reverberation rooms.