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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korea Society for Simulation
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Journal DOI :
The Korea Society for Simulation
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Volume & Issues
Volume 23, Issue 4 - Dec 2014
Volume 23, Issue 3 - Sep 2014
Volume 23, Issue 2 - Jun 2014
Volume 23, Issue 1 - Mar 2014
Selecting the target year
A Workflow Time Analysis Applying the Queueing Model
Park, Jinsoo ;
Journal of the Korea Society for Simulation, volume 23, issue 3, 2014, Pages 1~9
DOI : 10.9709/JKSS.2014.23.3.001
Traditional workflow time analyses have been performed treating an activity as an independent M/M/1queueing system. Using the general forms of performance measures in the M/M/1 system, various aspects of analyses can be performed. Especially, on the time analysis of an AND structure in a workflow system, the mean system sojourn time can be formalized by applying the performance measures of M/M/1 system. In the real workflow system, the AND structure cannot be described correctly under the assumption of independent M/M/1 systems. To overcome this limitation, this research makes the assumption that the all activities for a task starts simultaneously. In this situation, the theoretical solution can be derived using the performance measures of the M/G/1 system. In addition, the simulation modeling method will be proposed to analyze the AND structure of a real workflow system. Finally, some numerical results from the theoretical solutions and simulation models will be provided for verification. The main performance measures used in this research are mean queueing time and mean sojourn time.
Application of Common Random Numbers in Simulation Experiments Using Central Composite Design
Kwon, Chi-Myung ;
Journal of the Korea Society for Simulation, volume 23, issue 3, 2014, Pages 11~17
DOI : 10.9709/JKSS.2014.23.3.011
The central composite design (CCD) is often used to estimate the second-order linear model. This paper uses a correlation induction strategy of common random numbers (CRN) in simulation experiment and utilizes the induced correlations to obtain better estimates for the second-order linear model. This strategy assigns the CRN to all design points in the CCD. An appropriate selection of the axial points in CCD makes the weighted least squares (WLS) estimator be equivalent to ordinary least squares (OLS) estimator in estimating the linear model parameters of CCD. We analytically investigate the efficiency of this strategy in estimation of model parameters. Under certain conditions, this correlation induction strategy yields better results than independent random number strategy in estimating model parameters except intercept. The simulation experiment on a selected model supports such results. We expect a suggested random number assignment is useful in application of CCD in simulation experiments.
A New Bootstrap Simulation Method for Intermittent Demand Forecasting
Park, Jinsoo ; Kim, Yun Bae ; Lee, Ha Neul ; Jung, Gisun ;
Journal of the Korea Society for Simulation, volume 23, issue 3, 2014, Pages 19~25
DOI : 10.9709/JKSS.2014.23.3.019
Demand forecasting is the basis of management activities including marketing strategy. Especially, the demand of a part is remarkably important in supply chain management (SCM). In the fields of various industries, the part demand usually has the intermittent characteristic. The intermittent characteristic implies a phenomenon that there frequently occurs zero demands. In the intermittent demands, non-zero demands have large variance and their appearances also have stochastic nature. Accordingly, in the intermittent demand forecasting, it is inappropriate to apply the traditional time series models and/or cause-effect methods such as linear regression; they cannot describe the behaviors of intermittent demand. Markov bootstrap method was developed to forecast the intermittent demand. It assumes that first-order autocorrelation and independence of lead time demands. To release the assumption of independent lead time demands, this paper proposes a modified bootstrap method. The method produces the pseudo data having the characteristics of historical data approximately. A numerical example for real data will be provided as a case study.
Simulations Analysis of Proposed Structure Characteristics in Shallow Trench Isolation for VLSI
Lee, YongJae ;
Journal of the Korea Society for Simulation, volume 23, issue 3, 2014, Pages 27~32
DOI : 10.9709/JKSS.2014.23.3.027
In this paper, We are going to propose the novel structure with improved behavior than the conventional vertical structure for VLSI CMOS circuits. For this, the proposed structure is the moat shape for STI. We want to analysis the characteristics of simulations about the electron concentration distribution, oxide layer shape of hot electron stress, potential flux and electric field flux, electric field fo themal damage and current-voltage characteristics in devices. Physically based models are the ambient and stress bias conditions of TCAD tool. As a analysis results, shallow trench structure were trended to be electric functions of passive as device dimensions shrink. The electrical characteristics influence of proposed STI structures on the transistor applications become stronger the potential difference electric field and saturation threshold voltage, are decreased the stress effects of active region. The fabricated device of based on analysis results data were the almost same characteristics of simulation results data.
Analysis of Drifter's Critical Performance Factors Using Its Hydraulic Analysis Model
Noh, Dae-Kyung ; Seo, Jaho ; Park, Jin-Sun ; Park, James ; Jang, Joo-Sup ;
Journal of the Korea Society for Simulation, volume 23, issue 3, 2014, Pages 33~40
DOI : 10.9709/JKSS.2014.23.3.033
Drifter is equipment which is hard to localize. Performance of prototype hasn't performed well compared to product of leading companies even though advanced foreign firm's product were dead copied. This study shows cases of approaching the factor which produces performance gap through drifter hydraulic analysis model which is core component of rock drill. Progression of procedure is following. 1) Securing reliability of the analysis model by comparing impact test result with analysis result. 2) Drawing a graph which indicates performance gap between prototype and drifter of advanced foreign firm by using analysis model. 3) Approaching the factor which produces performance gap with analysing variable of the analysis model. Software used for this analysis is SimulationX.