• Journal of Korea Water Resources Association
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• v.31 no.6
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• pp.741-755
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• 1998

An extension of TOPMODEL was developed for rainfall-runoff simulation in agricultural watersheds equipped with tile drains. Tile drain functions are incorporated into the framework of TOPMODEL. Nine possible flow generation scenarios are suggested for tile drained watershed and applied in the modeling procedure. In the model development process, the traditional physically based storage approach and a new approach using a transfer function for the simulation of the flow in the unsaturated zone were compared. In order to provide better insight into the simulation process, a regionalized sensitivity analysis was performed to test the performance of the model and to compare the behavior of the transfer function to that of the simple storage related formulation. The results of analysis show good performance of the transfer function approach. Since the rainfall-runoff response pattern tends to vary seasonally, seven events distributed throughout a year were used in the sensitivity analysis to investigate the seasonal variation of the hydrologic characteristics. It is found that the sensitivity of each parameter described by the model are varied seasonally.

• Journal of the Society of Disaster Information
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• v.11 no.4
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• pp.493-505
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• 2015

Based on the typhoon paths landed on the southern coast of Korea, the distribution of typhoon moving directions follow the Beta probability density function and that of pressure drops in typhoon eyes follow the Rayleigh probability density function. Consequently, the extreme typhoon simulation scenarios for six landing positions are determined as most probable one in moving direction and extreme one of Typhoon Maemi level in pressure drop. The variation of storm surges in Masan bay associated with simulated typhoon landing position is analyzed through the numerical experiments in the next paper as the second part.

• Journal of the Korea Society for Simulation
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• v.20 no.2
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• pp.1-10
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• 2011

In queueing network analysis, arrival processes are usually modeled as renewal processes by matching mean and variance. The renewal approximation simplifies the analysis and provides reasonably good estimate for the performance measures of the queueing systems under moderate conditions. However, high variability in arrival process or in service process requires more sophisticated approximation procedures for the variability parameter of departure/arrival processes. In this paper, we propose an heuristic approach to refine Whitt's variability function with the k-interval squared coefficient of variation also known as the index of dispersion for intervals(IDI). Regression analysis is used to establish an empirical relationships between the IDI of arrival process and the IDI of departure process of a queueing system.

• Journal of the Korea Institute of Military Science and Technology
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• v.21 no.6
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• pp.767-775
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• 2018

To develop and check a Radar Processor Unit, checking the function and performance of the requirement is very important factor in developing Radar. General methods for verifying the Radar is simulation test, environment linkage test and field operation test, firstly, in case of requirement analysis phase, verify Radar algorithm and design by using mathematical method based simulation test method, and secondly, in case of unit test and integrated test phase, Test Equipment is set to simulate radar environment in the lab to verify radar function and performance. Lastly, field operation test phase is carried out to confirm the function and performance after it is mounted on the actual equipment. To successfully develop Radar Processor Unit, using the method of field operation test method after sufficient test cases are tested in radar environmental interlocking method in order to save cost and testing period and because of this reason, development of the Radar Processor Unit Test Equipment is becoming very important factor. In this paper, we introduce the concept of test equipment development and important factors in test equipment, which are target simulation, data processing and device interlocking.

• Tunnel and Underground Space
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• v.26 no.2
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• pp.100-109
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• 2016

This study suggests three spatial distribution functions of strength parameters, which can be adopted in the derivation of failure conditions for transversely isotropic rocks. All three proposed functions, which are the oblate spheroidal function, the exponential function, and the function based on the directional projection of the strength parameter tensor, consist of two model parameters. With assumption that the cohesion and friction angle can be described by the proposed distribution functions, the transversely isotropic Mohr-Coulomb criterion is formulated and used as a failure condition in the simulation of the conventional triaxial tests. The simulation results confirm that the failure criteria incorporating the proposed distribution functions could reproduce the general trend in the variations of the axial stress at failure and the directions of failure planes with varying inclination of the weankness planes and confining pressure. Among three distribution functions, the function based on the directional projection of the strength parameter tensor yields the highest axial strength, while the axial strength estimated by the oblate spheroidal distribution function is the lowest.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.2
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• pp.123-131
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• 2020

The system performance of naval multi function radar is affected by radar beam operation. Multi f function radar has to operate complicated beam better than search radar and tracking radar which have single operation. This paper describes fabricating analysis tool for the verification method for system performance of naval multi function radar. We composed the model that naval ship with MFR and radar which are detecting targets to verification the system performance. The targets are composed anti-aircraft and anti-ship. We integrate each model and make naval MFR simulator that applied resource management of track beam and search beam. We verify analysis tool by simulation in operating scenario after adjusting system parameter to analysis tool.

• Journal of the Korea Society of Computer and Information
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• v.25 no.6
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• pp.119-129
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• 2020

Software development activities are influenced by stochastic theory rather than deterministic one due to having process variability. Stochastic methods factor in the uncertainties associated with project activities and provides insight into the expected project outputs as probability distributions rather than as deterministic approximations. Thus, successful software projects systematically manage and balance five objectives based on historical probability: scope, size, cost, effort, schedule, and quality. Although software size estimation having much uncertainty in initial development has traditionally performed using deterministic methods: LOC(Lines Of Code), COCOMO(COnsructive COst MOdel), FP(Function Point), SLIM(Software LIfecycle Management). This research aims to present a function point method based on stochastic distribution and a case study based on Monte Carlo Simulation applying on an automotive electrical and electronics system software development. It is expected that the result of this paper is used as guidance for establishing of function point method in organizations and tools for helping project managers make decisions correctly.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.2
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• pp.87-96
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• 2020

The multi function radar is searching target and tracking through resource management at the same time. Increasing resource allotment of track, if more targets and faster the renewal rate of track, lead to decreasing quota of searching resource in limited resource. When the resource of search are decreased, it becomes degrade searching performance such as revisit time, number of detecting chance and tracking etc. Degraded performance of search reduces guided missile defense probability in complex strategy such as ship self defense. In this paper, we developed a modeling and simulation (M&S) tool that uses own-ship model, radar model, target model and defense model for analysis of self defense in complex strategy. We analyzed influence of ship self defense in complex strategy according to various target environments and track performance.

• Proceedings of the Korea Society for Simulation Conference
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• 1997.04a
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• pp.93-99
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• 1997

Most of the past studies on FMS scheduling problems may be classified into two classes, namely off-line scheduling and on-line scheduling approach. The off-line scheduling methods are used mostly for FMS planning purposes and may not be useful real time control of FMSs, because it generates solutions only after a relatively long period of time. The on-line scheduling methods are used extensively for dynamic real-time control of FMSs although the performance of on-line scheduling algorithms tends vary dramatically depending on various configurations of FMS. Current study is about finding a better on-line scheduling rules for FMS operations. In this study, we propose a method to create priority functions that can be used in setting relative priorities among jobs or machines in on-line scheduling. The priority functions reflect the configuration of FMS and the user-defined objective functions. The priority functions are generated from diverse dispatching rules which may be considered a special priority functions by themselves, and used to determine the order of processing and transporting parts. Overall system of our work consists of two modules, the Priority Function Evolution Module (PFEM) and the FMS Simulation Module (FMSSM). The PFEM generates new priority functions using input variables from a terminal set and primitive functions from a function set by genetic programming. And the FMSSM evaluates each priority function by a simulation methodology. Based on these evaluated values, the PFEM creates new priority functions by using crossover, mutation operation and probabilistic selection. These processes are iteratively applied until the termination criteria are satisfied. We considered various configurations and objective functions of FMSs in our study, and we seek a workable solution rather than an optimum or near optimum solution in scheduling FMS operations in real time. To verify the viability of our approach, experimental results of our model on real FMS are included.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.36 no.3
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• pp.203-211
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• 2023

A Markov chain Monte Carlo (MCMC) simulation is proposed for probabilistic full waveform inversion (FWI) in a layered half-space. Dynamic responses on the half-space surface are estimated using the thin-layer method when a harmonic vertical force is applied. Subsequently, a posterior probability distribution function and the corresponding objective function are formulated to minimize the difference between estimations and observed data as well as that of model parameters from prior information. Based on the gradient of the objective function, a proposal distribution and an acceptance probability for MCMC samples are proposed. The proposed MCMC simulation is applied to several layered half-space examples. It is demonstrated that the proposed MCMC simulation for probabilistic FWI can estimate probabilistic material properties such as the shear-wave velocities of a layered half-space.