• Proceedings of the Korea Society for Simulation Conference
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• 2003.06a
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• pp.91-100
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• 2003

In this paper we investigate the role that warfare played In the formation of the network of alliances between sites that are associated with the formation of the state in the Valley of Oaxaca, Mexico. A model of state formation proposed by Marcos and Flannery (1996) is used as the basis for an agent-based simulation model. Agents reside in sites and their actions are constrained by knowledge extracted from the Oaxaca Surface Archaeological Survey (Kowalewski 1989). The simulation is run with two different sets of constraint rules for the agents. The first set is based upon the raw data collected in the surface survey. This represents a total of 79 sites and constitutes a minimal level of warfare (raiding) in the Valley. The other site represents the generalization of these constraints to sites with similar locational characteristics. This set corresponds to 987 sites and represents a much more active role for warfare in the Valley. The rules were produced by a data mining technique, Decision Trees, guided by Genetic Algorithms. Simulations were run using the two different rule sets and compared with each other and the archaeological data for the Valley. The results strongly suggest that warfare was a necessary process in the aggregations of resources needed to support the emergence of the state in the Valley.

• The Journal of Information Systems
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• v.30 no.1
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• pp.151-177
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• 2021

Purpose This paper aims to improve management performance by effectively responding to production needs and reducing inventory through synchronizing production planning and procurement in the aviation industry. In this study, the differences in production planning and execution were first analyzed in terms of demand, supply, inventory, and process using the big data collected from a domestic aircraft manufacturers. This paper analyzed the problems in procurement and inventory management using legacy big data from ERP system in the company. Based on the analysis, we performed a simulation to derive an efficient procurement and inventory management plan. Through analysis and simulation of operational data, we were able to discover procurement and inventory policies to effectively respond to production needs. Design/methodology/approach This is an empirical study to analyze the cause of decrease in inventory turnover and increase in inventory cost due to dis-synchronize between production requirements and procurement. The actual operation data, a total of 21,306,611 transaction data which are 18 months data from January 2019 to June 2020, were extracted from the ERP system. All them are such as basic information on materials, material consumption and movement history, inventory/receipt/shipment status, and production orders. To perform data analysis, it went through three steps. At first, we identified the current states and problems of production process to grasp the situation of what happened, and secondly, analyzed the data to identify expected problems through cross-link analysis between transactions, and finally, defined what to do. Many analysis techniques such as correlation analysis, moving average analysis, and linear regression analysis were applied to predict the status of inventory. A simulation was performed to analyze the appropriate inventory level according to the control of fluctuations in the production planing. In the simulation, we tested four alternatives how to coordinate the synchronization between the procurement plan and the production plan. All the alternatives give us more plausible results than actual operation in the past. Findings Based on the big data extracted from the ERP system, the relationship between the level of delivery and the distribution of fluctuations was analyzed in terms of demand, supply, inventory, and process. As a result of analyzing the inventory turnover rate, the root cause of the inventory increase were identified. In addition, based on the data on delivery and receipt performance, it was possible to accurately analyze how much gap occurs between supply and demand, and to figure out how much this affects the inventory level. Moreover, we were able to obtain the more predictable and insightful results through simulation that organizational performance such as inventory cost and lead time can be improved by synchronizing the production planning and purchase procurement with supply and demand information. The results of big data analysis and simulation gave us more insights in production planning, procurement, and inventory management for smart manufacturing and performance improvement.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.5
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• pp.35-43
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• 2014

A data allocation technique is essential to improve the performance of data broadcast systems. This paper explores the issues for allocating data items on broadcast channels in the environment where multiple-data queries are submitted, and proposes a new data allocation scheme named DAMA. The proposed scheme employs the strategy that the broadcast frequency of each data is determined by the moving average of its access probability. DAMA could enhance the performance of query response time since it is capable of controlling the influence of access probability properly according to the query size. Simulation is performed to evaluate the performance of the proposed scheme. The simulation results show that the performance of DAMA is superior to other schemes in terms of the average response time.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.38 no.2
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• pp.97-107
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• 2020

To analyze temporal and spatial changes in vegetation, it is necessary to determine the associated continuous distribution and conduct growth observations using time series data. For this purpose, the normalized difference vegetation index, which is calculated from optical images, is employed. However, acquiring images under cloud cover and rainfall conditions is challenging; therefore, time series data may often be unavailable. To address this issue, La et al. (2015) developed a multilinear simulation method to generate missing images on the target date using the obtained images. This method was applied to a small simulation area, and it employed a simple analysis of variables with lower constraints on the simulation conditions (where the environmental characteristics at the moment of image capture are considered as the variables). In contrast, the present study employs variables that reflect the growth characteristics of vegetation in a greater simulation area, and the results are compared with those of the existing simulation method. By applying the accumulated temperature, the average coefficient of determination (R²) and RMSE (Root Mean-Squared Error) increased and decreased by 0.0850 and 0.0249, respectively. Moreover, when data were unavailable for the same season, R² and RMSE increased and decreased by 0.2421 and 0.1289, respectively.

• KIEAE Journal
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• v.13 no.6
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• pp.77-82
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• 2013

Light environment in the school building is one of the most important elements of the plan in order to improve student's ability to learn and the healthy growth. Thus, the window plan of the school building is a great addition to improve environmental-friendly performance through the daylight control. Daylight is highly beneficial for improving the indoor environmental quality and reducing building energy consumption, daylighting applications are scarcely considered, especially during the school building design process, because of lack of previous studies on the light environment of student and complex simulation process. Therefore, daylighting process were performed using ECOTECT, which has various advantage such as easy user interface and simple simulation processes. ECOTECT simulation were performed using weather data. As a result, ECOTECT simulation are performed for daylight autonomy and useful daylight illuminance. Using this data, Window planing is to propose and effective method in the early stages of design.

• 한국정보통신설비학회:학술대회논문집
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• 2006.08a
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• pp.39-42
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• 2006

There are various analysis functions(including prediction of path loss, analyzing of capacity and coverage, etc.) of simulation tool to design and optimize the mobile communication network. Its reliability absolutely effects the performance of mobile communication network. Especially as the wireless network highly advancing focused on data service, it more needs to research and develop on the standard establishment of reliability of the simulation tool. Also it is important the systematic research how to improve the reliability of simulation tool. In this paper, to give the concrete process and skill about how to improve reliability, we define the kinds of reliability at first. And then we explain the comparison results between real field measurement data and theoretic simulation data.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.6
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• pp.1533-1545
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• 1996

In this paper, the design and implementation of echo canceller with new variable step size algorithm is discussed. The method used in the new algorithm is to periodically adopt the test function which helps an optimal coefficient tracking. This algorithm outperforms LMS and VS algorithms in convergence speed and steady state error. As the period of test function is decreased, the speed of convergence is improved, but the number of calculation is increased, then the trade off between these parameters must be considered. Simulation results show new algorithm outperforms LMS and VS algorithms in convergence rate. For the design of hardware, circuit is designed with VHDL, and synthesized with Act1 withc is a FPGA library of ActelTM in use of synovation of InterGraph$^{TM}$. Verification of the synthesized circuit is carried out with simulator DLAB. The circuit based on the algorithm which is suggested in this paper calculated 7 radix places of inary number. A simulation data for the verification is based on the data of algorithm simulation. When the same input data is applied to the both simulation, output results of circuit simulation had slight difference in compare with that of algorithm simulation. The number of used gate is about 5,500 and We have 5.53MHz in maximum frequency.y.

• Journal of Korean Academy of Nursing
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• v.48 no.5
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• pp.588-600
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• 2018

Purpose: The purpose of this study was to test a model of nursing competencies of nursing simulation learners. The conceptual model was based on the theory of Jeffries's simulaton theory. Methods: Data collection was conducted in October 2017 for 310 students from two nursing universities in Kyungbuk area for 20 days. Data analysis methods were covariance structure analysis using SPSS 21.0 and AMOS 22.0 statistical programs. Results: The hypothetical model was a good fit for the data. The model fit indices were comparative fit index=.97, normed fit index=.94, Tucker-Lewis Index=.97, root mean square error of approximation=.44, and standardized root mean square residual=.04. Teacher factors were directly related to simulation design characteristics, and it was confirmed that the curriculum, classroom operation and teaching method of the instructors were important factors. Learner factors were found to have a direct effect on nursing competence, self-confidence, and clinical performance that belong to nursing capacity. In particular, the results of this study indicate that the simulation design characteristics have a partial mediating effect on learner factors and clinical performance, and a complete mediating effect on learner factors and clinical judgment ability. Conclusion: In order to improve the learner's clinical performance and clinical judgment ability, it is necessary to conduct practical training through nursing simulation besides preparing the learner and the educator.

• Journal of Korean Society for Atmospheric Environment
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• v.2 no.1
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• pp.81-90
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• 1986

Hanna - Gifford Model and Air Quality Display Model(AQDM) were validated in the simulation of $SO_2$ and TSP concentrations of Seoul City. The observed data which were measured at 16 sites of air monitoring system conducted by Seoul metropolitan city in 1984 were compared with the simulated data and the results were obtained as follows; 1. Several different meteorological data were examined: The particularities of meteorological data was not an influencing factor in the validity of simulation. The simulations of $SO_2$ by Hanna - Gifford model and by AQDM showed close correlation coefficients between the observed data and the simulated data (r = 0.71 - 0.78). 2. The simulation models showed different validities with the seasonal variation: The correlation coefficients (r) between the observed and the simulated by Hanna - Gifford Model for $SO_2$ and TSP were 0.86 and 0.80 in Spring, 0.63 and 0.66 in Summer, 0.76 in Autumn and 0.81 and 0.93 in Winter respectively. Those by AQDM were 0.73 and 0.68 in Spring, 0.56 and 0.79 in Summer, 0.77 and 0.76 in Autumn and 0.64 and 0.68 in Winter respectively. 3. The simulated data by two models had a close relationships: The correlation coefficients between them were 0.96 for $SO_2$, and 0.93 for TSP. With the above results, the application of models was discussed; Hanna - Gifford model was less valid in the simulation for the air quality of $SO_2$ and TSP in Seoul in Summer and AQDM also was not valid for $SO_2$ in Summer and in Winter and for TSP in Spring.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.235-236
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• 2002

Tribological phenomena such as wear or transfer are influenced by various factors and have complicated behavior. Therefore, it is difficult to predict the behavior of the gribological phenomena because of their complexity. But, those tribological phenomena can be considered simply as to transfer micro material particles from the sliding interface. Then, we proposed the numerical simulation method for tribological phenomena such as wear of transfer using stochastic process models. This numerical simulation shows the change of the 3-D surface topography. In this numerical simulation, initial 3-D surface toughness data are generated by the method of non-causal 2-D AR (autoregressive) model. Processes of wear and transfer for some generated initial 3-D surface data are simulated. Simulation results show successfully the change of the 3-D surface topography.