• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.4
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• pp.805-814
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• 2013

According to the shut-down of Analog TV service on 30th. December, 2012, UHF Digital Dividend Band (698~806MHz) could be used for Mobile service such as LTE(Long Term Evolution). In the condition that this band is allocated for LTE service, Interference evaluation between LTE and adjacent DTV service was carried out, using LTE-A system-level simulator which was developed for simulation of IMT-Advanced technology. If LTE service be commercialized in this band, this study proposes the coexistence condition through the interference evaluation such as the effects not only to DTV receiver from LTE terminal but also to LTE base station from DTV transmitter. It is expected that the coexistence condition by these studies will be applied to network algorism for IMT-Advanced system in this band.

• Journal of Korea Water Resources Association
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• v.38 no.2
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• pp.167-177
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• 2005

In this study, the PRMS(Precipitation and Runoff Modeling System), developed by USGS(United States Geological Survey), was applied to the Yongdam dam watershed in the Geum River basin. The efficiency for runoff simulation and spatial characteristics of PRMS were evaluated. The runoff changes with the changes of subcatchments and HRUs were estimated. As results, the size of the subcatchment and HRV did not significantly affect the runoff at the exit of watershed. Consequently, the spatial characteristic of PRMS was shown as lumped type rather than semi-distributed. The geographical input data for Yongdam dam watershed were converted to the USGS Input type, and the parameters were calibrated using Rosenbrock optimization method, validated with the observed runoff data. The PRMS showed resonable agreements in the long-term continuous runoff simulation, if the accuracy of observed data is ensured.

• Journal of the Society of Naval Architects of Korea
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• v.53 no.5
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• pp.380-387
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• 2016

Present research target to develop the procedure of long-term fatigue analysis of the structural details near the upper rolling chock of IMO type B tank by using the time domain modal analysis technique where both the contact and friction behavior can be accurately simulated. In order to perform the time domain analysis focused on the contact and friction, the entire model of the hull and tank was condensed with DOF reduction technique, which is obtained by transforming the global finite element model into its quasi-static modal coordinate. Modal analysis using the quasi-static deformation modes is chosen as a cost effective time domain simulation method and this is based on the fact that the structural response of the tank is quasi-static. Based on the developed cost effective time domain simulation method, the long-term fatigue analysis procedure for the structural details near the rolling chock and key of independent type tank is targeted to be established. The developed fatigue assessment procedure takes into account, wave induced stress and both contact and friction induced stress without loss of accuracy.

• Korean Journal of Construction Engineering and Management
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• v.5 no.2 s.18
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• pp.211-218
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• 2004

In a large owner organization, a program manager of multiple maintenance and remodeling projects has experienced increasing scale and complexity of coordinating the M/R projects with in-house technicians who belong to multiple trade shops. This paper proposes a dual-level hierarchical planning strategy that consists of a program master plan in the long-term horizon and a master construction schedule in an operational scheduling window. A rolling horizon approach to the program master plan is proposed to deal with the external uncertainty of unknown stream of project requests. A resource-constrained scheduling algorithm is developed to generate the master construction schedule in a scheduling window. During development of the algorithm, more emphasis is placed on long-term organizational resource continuity, especially flow management of program constraint resources, than ephemeral events of an individual activity and project. Monte Carlo simulation experiments of three scheduling windows are used to evaluate the relative performance of the proposed scheduling algorithm against three popular scheduling heuristics for resource-constrained multiple projects.

• Journal of Korea Water Resources Association
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• v.35 no.6
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• pp.693-701
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• 2002

In this study, one dimensional sediment movement numerical model(HEC-6) and semi-two dimensional sediment movement numerical model(GSTARS 2.1) were applied to solve the change of channel geometry in Bocheong stream. GSTARS 2.1 model was applied for the three selected sediment transport formulas(Ackers and White's, Engelund and Hanson, Yang formula) from 1993 to 2000 measured data on each section. The simulation results of Ackers and White formula for long -term bed changes are good when compared to the measured data. The HEC-6 model was applied for the simulation of one dimensional sediment movement for the same period. Comparison of the long-term simulations by GSTARS 2.1 and HEC-6 models with measured data shows that simulations by both models are in fair agreement with measured data in overall trend of the river bed changes. Comparisons of simulated cross sectional bed-elevations with measured data shows that GSTARS 2.1 model gives better agreement with than simulated results bed changes on the HEC-6 model.

• Journal of Advanced Navigation Technology
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• v.23 no.5
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• pp.408-414
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• 2019

We developed a surveillance tool for collision avoidance of unmanned aerial vehicles (UAVs) in urban areas. In our tool, users can visualize the safety distance on the actual 3D map of urban area. The estimated positions of UAVs are assumed to be obtained based on the long-term evolution (LTE) signals. The safety distance is defined to include two or more signals with bias. The safety distance calculation method used in this paper enables simulation similar to the actual urban areas where signals are frequently biased due to multipath. In the simulation, the parameters were set based on the measured values, and the change of the safety distance according to the number of faulty signals was simulated. As a result, increasing the number of faulty signals led to a longer safety distance as expected.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.5
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• pp.177-183
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• 2022

Recently, interesting of home training is getting bigger due to COVID-19. Accordingly, research on applying HAR(human activity recognition) technology to home training has been conducted. However, existing paper of HAR proposed static activity instead of dynamic activity. In this paper, the deep learning model where dynamic exercise posture can be analyzed and the accuracy of the user's exercise posture can be shown is proposed. Fitness images of AI-hub are analyzed by blaze pose. The experiment is compared with three types of deep learning model: RNN(recurrent neural network), LSTM(long short-term memory), CNN(convolution neural network). In simulation results, it was shown that the f1-score of RNN, LSTM and CNN is 0.49, 0.87 and 0.98, respectively. It was confirmed that CNN is more suitable for human activity recognition than other models from simulation results. More exercise postures can be analyzed using a variety learning data.

• Geomechanics and Engineering
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• v.20 no.6
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• pp.517-525
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• 2020

The long-term stability of rock engineering is significantly affected by the time-dependent deformation behavior of rock, which is an important mechanical property of rock for engineering design. Although the hard rocks show small creep deformation, it cannot be ignored under high-stress condition during deep excavation. The inner mechanism of creep is complicated, therefore, it is necessary to investigate the relationship between microscopic creep mechanism and the macro creep behavior of rock. Microscopic numerical modeling of sandstone creep was performed in the investigation. A numerical sandstone sample was generated and Parallel Bond contact and Burger's contact model were assigned to the contacts between particles in DEM simulation. Sensitivity analysis of the microscopic creep parameters was conducted to explore how microscopic parameters affect the macroscopic creep deformation. The results show that the microscopic creep parameters have linear correlations with the corresponding macroscopic creep parameters, whereas the friction coefficient shows power function with peak strength and Young's modulus, respectively. Moreover, the microscopic parameters were calibrated. The creep modeling curve is in good agreement with the verification test result. Finally, the creep curves under one-step loading and multi-step loading were compared. This investigation can act as a helpful reference for modeling rock creep behavior from a microscopic mechanism perspective.

• Journal of the Korean Institute of Navigation
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• v.23 no.1
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• pp.65-74
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• 1999

For the purpose of analyzing the influence of the recent environmental changes of container logistics system in container terminal, the simulation model of container logistics system on BCTOC is developed in this paper. The simulation model is accomplished by the AweSim simulation language, and the several data which have been used in simulation gained through spot research and basic statistic analysis using the first half of 1998 electronic data in BCTOC. The results of this study are as follows; (1) In the case of BCTOC, the decreasing of container volumes is observed during the first half of 1998 compare with that of 1997. (2) In the container handling service market, the monopolistic market system in the past rapidly diverts to the competition market system from now. (3) From the simulation results, the improving of container logistics system is observed. (4) Because of these results, BCTOC will come to strengthen customer service and competitive power through starting On-Dock service system and operating the team of customer management in the long term.

• Proceedings of the KIEE Conference
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• 2006.11a
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• pp.275-278
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• 2006

This paper describes a probabilistic annual congestion cost assessment of a grid at a composite power system derived from a model. This probabilistic congestion cost assessment simulation model includes capacity limitation and uncertainties of the generators and transmission lines. In this paper, the proposed probabilistic congestion cost assessment model is focused on an annualized simulation methodology for solving long-term grid expansion planning issues. It emphasizes the questions of "how should the uncertainties of system elements (generators, lines and transformers, etc.) be considered for annual congestion cost assessment from the macro economic view point"? This simulation methodology comes essentially from a probabilistic production cost simulation model of composite power systems. This type of model comes from a nodal equivalent load duration curve based on a new effective load model at load points. The characteristics and effectiveness of this new simulation model are illustrated by several case studies of a test system.