• Structural Engineering and Mechanics
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• v.54 no.5
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• pp.937-953
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• 2015

This paper investigates the load model for single footfall trace of human walking. A large amount of single person walking load tests were conducted using the three-dimensional gait analysis system. Based on the experimental data, Fourier series functions were adopted to model single footfall trace in three directions, i.e. along walking direction, direction perpendicular to the walking path and vertical direction. Function parameters such as trace duration time, number of Fourier series orders, dynamic load factors (DLFs) and phase angles were determined from the experimental records. Stochastic models were then suggested by treating walking rates, duration time and DLFs as independent random variables, whose probability density functions were obtained from experimental data. Simulation procedures using the stochastic models are presented with examples. The simulated single footfall traces are similar to the experimental records.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.387-388
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• 2006

This article provides a dynamic analysis model for huge marine engine that examined analytically variation effects of frequency response by fitting of transverse stays such as hydraulic type. First, vibration analysis using the three dimensional finite element models for the huge marine engine has performed in order to find out the dynamic characteristics. Second, three dimensional finite elements model for the huge marine engine was modifued so that generate forcing nodes in crosshead part and top bracing nodes in cylinder frame part. Third, a system matrix and output matrix was derived for the general siso(single input single out) state space model. Finally, developed state space model for the three dimensional finite elements model for the huge marine engine without the additional modifying process.

• Proceedings of the Korea Water Resources Association Conference
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• 1987.07a
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• pp.113-122
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• 1987

A numerical simulation technique of three-dimensional finite difference model is developed to study the groundwater flow system in Dcjima, an upland area which faces Kasumigaura Lake. For general perspectives of the groundwater flow system, a steady state three-dimentional model is simulated. For the sedimentary mud formations which are found in the representative formation, three situations of hydraulic conductivity are considered, representing an isotropic condition and situations where the horizontal permeability is equal to 10 times and 100times of the vertical one. The finite difference grid used in the simulation has 60x50x30=90,000 nodes. A converged solution with a tolerance of 0.001 meter of hydraulic head is set. Having determined the flow net by using a steady state three-dimensional model. the results for the three cases of hydraulic conductivity are compared with the results of tracer methods (Bae and Kayane 1987) With the aid of four representative vertical cross-sections, groundwater flow systems in the study area are assumed. Water balances for the three cases indicate very good agreement between total recharge and discharge in each case Analyses of groundwater flow system based on the tritium concentrations and water quality measurements (Bae and Kayane 1987) are confirmed by the numerical simulation and the results obtained by these two methods appeared to be in close agreement.

• Journal of Korean Institute of Industrial Engineers
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• v.5 no.2
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• pp.21-36
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• 1979

Static muscle contractions when prolonged or frequently repeated result in discomfort, fatigue, and musculosketal injuries. An analytic and quantitative model has been developed in order to expand the working knowledge on muscle fatigue. In this paper, three Markov models of muscle fatigue are developed. These models are based on motor unit fatigue-recovery characteristics obtained from information on motor unit behavior as it relates to fatigue and graded exertions. Three successively more realistic models are developed that involve: (1) homogeneous motor units with intensity-dependent fatigue rates and state-independent recovery rates (the HMSI model); (2) homogeneous motor units, intensity-dependent fatigue rates and state-dependent recovery rates (the HMSD model); and (3) non-homogeneous motor units (i.e., Type S and Type F), intensity-dependent fatigue rates and state-dependent recovery rates (the HMSD model). The result indicate that a simple stochastic model provide a means to analyze the complex nature of muscle fatigue in sequential static exertions.

• Journal of the Korea Society for Simulation
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• v.21 no.1
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• pp.27-34
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• 2012

Proposed in the paper is an agent based and object-oriented methodology to create a virtual logistics support system model. The proposed virtual logistics support system model consists of three types of objects: the logistics force agent model(static model), the military supplies transport manager model(function model), the military supplies state manager model(dynamic model). A logistic force agent model consists of two agent: main function agent and function agent. To improve the reusability and composability of a logistics force agent model, the function agent is designed to adapt to different logistics force agent configuration. A military supplies transport manager is agent that get information about supply route, make decisions based on decision variables, which are maintained by the military supplies state manager, and transport military supplies. A military supplies state manager is requested military supplies from logistics force agent, provide decision variables such as the capacity, order of priority. For the implementation of the proposed virtual logistics force agent model, this paper employs Discrete Event Systems Specification(DEVS) formalism.

• Communications for Statistical Applications and Methods
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• v.29 no.3
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• pp.353-371
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• 2022

This paper analyzes death counts after World War II of several countries to identify and to compare their stochastic structures. The stochastic structures that this paper entertains are three structural time series models, a local level with a random walk model, a fixed local linear trend model and a local linear trend model. The structural time series models assume that a time series can be formulated directly with the unobserved components such as trend, slope, seasonal, cycle and daily effect. Random effect of each unobserved component is characterized by its own stochastic structure and a distribution of its irregular component. The structural time series models use the Kalman filter to estimate unknown parameters of a stochastic model, to predict future data, and to do filtering data. This paper identifies the best-fitted stochastic model for three types of death counts (Female, Male and Total) of each country. Two diagnostic procedures are used to check the validity of fitted models. Three criteria, AIC, BIC and SSPE are used to select the best-fitted valid stochastic model for each type of death counts of each country.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.10a
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• pp.220-225
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• 2013

In this study, active control system using sliding mode control method is presented to achieve the gust response alleviation of a three-dimensional flexible wing model. For this purpose, aeroservoelastic model which is composed of aeroelastic plant, control surface actuator model, and gust model depicting the atmospheric turbulence is formulated in the state space. The aerodynamic force generated by the motion of a trailing edge control surface of a flexible wing is made use of as control means. An active control system combining state feedback sliding mode controller and state estimator based on measured responses such as wing tip acceleration and wing root strain is designed for gust response alleviation of a flexible wing aeroservoelastic model. The performance of the controller designed is demonstrated via numerical simulation for the representative flexible wing model under gust loading conditions.

• Journal of Labour Economics
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• v.41 no.3
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• pp.95-128
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• 2018

This study tries to measure the change in the state dependence of the three labor supply choices (part-time, full-time, and the state of unemployed) in Korean married women's labor market by estimating the dynamic multinomial logit model based on MSL (maximum simulated likelihood) method. A component representing individual's unobserved characteristics has been introduced, because it is crucial to control for unobserved heterogeneity in assessing the state dependence. Estimation results show that the state dependences of the three alternatives have strengthened recently. Therefore, part-time job has become more likely to be functioning as an extra option to participate in labor market rather than a bridge(stepping stone) or shelter between unemployment and full-time job.

• Computers and Concrete
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• v.19 no.5
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• pp.527-535
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• 2017

In this study, an aging deformation statistical model for a unique high and steep rock slope was proposed, and the aging characteristic of the slope deformation was better reflected. The slope displacement was affected by multiple-environmental factors in multiple scales and displayed the same tendency with a rising water level. The statistical model of the high and steep rock including non-aging factors was set up based on previous analyses and the study of the deformation and residual tendency. The rule and importance of the water level factor as a non-aging unit was analyzed. A partitioned statistical model and mutation model were established for the comprehensive cumulative displacement velocity with the monitoring study under multiple factors and multiple parameters. A spatial model was also developed to reflect and predict the whole and sectional deformation character by combining aging, deformation and space coordinates. A neural network model was built to fit and predict the deformation with a high degree of precision by mastering its feature of complexity and randomness. A three-dimensional finite element model of the slope was applied to approach the structure character using numerical simulations. Further, a three-dimensional finite element model of the slope and dam was developed, and the whole deformation state was analyzed. This study is expected to provide a powerful and systematic method to analyze very high, important and dangerous slopes.

• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.317-319
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• 2019

In this paper, a three level duty cycle controlled half bridge LLC converter for EV charger application is presented. The topology and operating regions of the converter are discussed. The equations of the converter are derived in time domain. A small signal model of the converter is developed by perturbation and linearization of the steady state model about their operating point using Extended Describing function.