• Journal of Korean Elementary Science Education
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• v.34 no.4
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• pp.357-371
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• 2015

Even after learning electric current, elementary school students have various non-scientific conceptions and difficulties. Because flow of charge is not visible. Also elementary school students do not learn theory but phenomena, so they cannot transfer theoretical perspective to new situation. In this research, we have designed instruction based on PhET simulation visualizing flow of electric charge and applied it to 37 science-gifted students in elementary school for measuring conceptual understanding. As a result, six out of the seven Hake gains of question set are high gain and just one is middle gain because the students have understood the flow pattern of the charge through circuit elements such as light bulbs, wire, as well as battery with PhET simulation and it gives a chance to create various questions spontaneously about electric current. Also they become able to do spontaneous mental simulation without PhET simulation about flow of charges. This research, suggest that developed materials using PhET simulation could be used as not only program for gifted students in elementary school, but also the electrical circuit section in an elementary science curriculum.

• Proceedings of the Korea Society for Simulation Conference
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• 2003.11a
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• pp.35-40
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• 2003

This paper presents a method for designing layout on the yard and evaluating alternative designs of the layout by applying simulation. The method is based on the concepts of the conventional port container terminal with a perpendicular yard layout. In general, yard design of the container terminal is consists of the two major parts. One is to divide yard area between the number of sections and the number of runs and the other is to decide the number of equipment that is the yard truck and yard crane. In the past days, this design was depended on the experience of the terminal operator and the structure of the conventional terminal layout because it is a very complex decision problem. In this paper we suggest the method of yard design as a conceptual procedure and estimate the efficiency of the container crane and the optimal the number of equipment using the simulation. Numerical examples are provided in order to illustrate the conceptual procedure. As the example, the suggested method and simulation are applied to the virtual container terminal with a perpendicular yard layout. In the results, the number of sections and runs on yard area, the number of yard truck per container crane and the number of yard crane per run are decided. In additional, the traffic among blocks on yard layout is estimated in terms of rate.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1241-1245
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• 2011

High RAM performance and efficient operation plan and maintenance equipment and policies are needed for improving the system availability performance such as punctuality and schedule adherence while reducing life cycle cost. Because railway systems are repairable, complex and have multi-echelon maintenance support structure, it is much complicated to set RAM performance targets and operation and maintenance plan. It is not easy to solve these problem by mathematical method and simulation can be consider for them. This article suggests the conceptual simulation model for analysing availability of railway system which has complex system structure and operation/maintenance environment.

• Journal of computational fluids engineering
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• v.10 no.3 s.30
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• pp.63-69
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• 2005

The COMS, the first meteorological geostationary satellite in Korea, is under development by KARI. The radiator size and the heater power for the thermal control of COMS are calculated using an analytic method. The total radiator area of $4.85\;m^2$ and the total heater power of 794.77 W are determined at a conceptual design of COMS. The commercial software, SINDA and TRASYS, are utilized in order to compare and verify the analytic results. The results of on-orbit numerical simulation of cold and hot cases show that the radiator size and heater power obtained from the analytic method are appropriate to maintain COMS equipments within required temperature ranges.

• Journal of the Korea Institute of Military Science and Technology
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• v.12 no.4
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• pp.407-414
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• 2009

This paper describes a conceptual model for the performance analysis simulator of a weapon launching system. The system performance analysis simulator is envisioned to provide an integrated analysis environment in which the system performance and operational effectiveness can be analyzed in more rapid and efficient way. The conceptual model for the simulator describes a referent independently of specific technology and implementation, and it can be used to transform the simulator requirements into the simulator system specifications.

• International Journal of Aeronautical and Space Sciences
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• v.15 no.4
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• pp.366-373
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• 2014

A conceptual design of a three-surface strike fighter was studied and stealth performance was taken into account to enhance survivability and battle effectiveness. CATIA was used to design the aircraft's three-dimensional prototype model and the weapon carriage arrangement was also studied. The aircraft's RCS characteristics and distributions under X, S, C, and L bands were simulated using the RCSPlus software, which is based on the PO method. Pressure and velocity distributions of the flow field were also simulated using CFD. A turbulence model was based on standard $k-{\varepsilon}$ function and N-S functions were used during the CFD computation. Lift coefficients, drag coefficients, and lift-to-drag ratio were obtained by aerodynamic simulation. The results showed that: (1) the average value of head-on RCS between ${\pm}30^{\circ}$ is below -3.197 dBsm, and (2) the lift coefficient is 0.34674, the drag coefficient is 0.04275, and the lift-to-drag ratio is 8.11087 when the attack angle is $2.5^{\circ}$.

• Environmental Engineering Research
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• v.25 no.3
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• pp.366-373
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• 2020

The autonomous vehicles (AVs) could make a positive or negative impact on reducing mobile emissions. This study investigated the changes of mobile emissions that could be caused by large-scale adoption of AVs. The factors of road capacity increase and speed limit increase impacts were simulated using a conceptual modeling approach that combines a hypothetical speed-emission function and a traffic demand model using a virtual transportation network. The simulation results show that road capacity increase impact is significant in decreasing mobile emissions until the market share of AVs is less than 80%. If the road capacity increases by 100%, the mobile emissions will decrease by about 30%. On the other hand, driving speed limit increase impact is significant in increasing mobile emissions, and the environmentally desirable speed limit was found at around 95 km/h. If the speed limit increases to 140 km/h, the mobile emissions will increase by about 25%. This is because some vehicles begin to bypass the congested routes at high speeds as speed limit increases. Based on the simulation results, it is clear that the vehicle platooning technology implemented at reasonable speed limit is one of the AV technologies that are encouraging from the environmental point of view.

• Journal of the Korea Institute of Military Science and Technology
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• v.15 no.6
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• pp.754-760
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• 2012

To improve the efficiency and economics of national defence, the needs for defence M&S systems are greatly increased, but the lack of interoperability and reusability lowers the level of reliability in the existing simulations models. Recently, many research activities have been performed and some conceptual models, such as CMMS, DCMF, and KAMA, were introduced. However, these models don't support the whole process of defence M&S system development nor provide integrated domain knowledge and up-to-date data. In this paper, we analyzed the analysts' guidances and doctrines, which are the basic ingredients for the simulation system development, and proposed a systematic structure for all the defence M&S stakeholders to share the standardized domain knowledge, modeling algorithm and data. This will be a logical bridge between Mission Space and Simulation Space, and provide substantial data sets to build simulation systems.

• Proceedings of the Korea Society for Simulation Conference
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• 2001.10a
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• pp.391-395
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• 2001

Model verification, validation and accreditation (VV&A) of system simulation are detailedly discussed in this paper. The necessity of VV&A is explained by analyzing the factors on which the model and the reality are discrepant. The W&A technology is expounded in detail not only in the conceptual aspect but also in the methodological aspect. Some principles, difficulties and problems that should be paid attention to are discussed concretely and reasonedly. The paper is expected to be instructional and helpful to the VV&A study.

• Journal of Environmental Science International
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• v.22 no.5
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• pp.523-531
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• 2013

In this study, a method of simulating ephemeral stream runoff characteristics in Jeju watershed is newly suggested. The process based conceptual-physical scheme is established based on the SWAT-K and applied to Cheonmi-cheon watershed which shows the typical pattern of ephemeral stream runoff characteristics. For the proper simulation of this runoff, the intermediate flow and baseflow are controlled to make downward percolation should be dominant. The result showed that surface runoff simulated by using the modified scheme showed good agreement with observed runoff data. In addition, it was found that the estimated runoff directly affected the groundwater recharge rate. This conceptual model should be continuously progressed including rainfall interception, spatially estimated evapotranspiration and so forth for the reasonable simulation of the hydrologic characteristics in Jeju island.