• Journal of the Korean Society of Safety
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• v.33 no.2
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• pp.132-137
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• 2018

Compared with general rivers, fluctuations of the water level and the river bed are severe in the tidal river. In hydro-dynamic aspect, such fluctuation gives different river-bed data to us according to observing period. The time-dependent river-bed data and pre-estimation of the Manning's roughness coefficient which is the key factor of numerical modelling induces uncertainty of evaluating the design flood level. Thus it is necessary to pay more attention to calculate the flood level at tidal rivers than at general rivers. In this study, downstream of the Imjin River where is affected by tide of the West Sea selected as a study site. From the numerical modelling, it was shown that the unsteady simulation gave considerable mitigation of the water level from the starting point to 15 km upstream compared to the steady simulation. Either making a detention pond or optional dredging was not effective to mitigate the flood level at Gugok - Majung region where is located in the downstream of the Imjin River. Therefore, a more sophisticated approach is required to evaluate the design flood level estimation before constructive measures adopted in general rivers when establishing the flood control plan in a tidal river.

• Tunnel and Underground Space
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• v.31 no.5
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• pp.309-332
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• 2021

Natural barrier systems surrounding the geological repository for the high-level radioactive waste should guarantee the hydraulic performance for preventing or delaying the leakage of radionuclide. In the case of the behavior of a crystalline rock, the hydraulic performance tends to be decided by the existence of discontinuities, so the coupled hydro-mechanical(HM) processes on the discontinuities should be characterized. The discontinuum modelling can describe the complicated behavior of discontinuities including creation, propagation, deformation and slip, so it is appropriate to model the behavior of a crystalline rock. This paper investigated the coupled HM processes in discontinuum modelling such as UDEC, 3DEC, PFC, DDA, FRACOD and TOUGH-UDEC. Block-based discontinuum methods tend to describe the HM processes based on the fluid flow through the discontinuities, and some methods are combined with another numerical tool specialized in hydraulic analysis. Particle-based discontinuum modelling describes the overall HM processes based on the fluid flow among the particles. The discontinuum methods that are currently available have limitations: exclusive simulations for two-dimension, low hydraulic simulation efficiency, fracture-dominated fluid flow and simplified hydraulic analysis, so it could be improper to the modelling the geological repository. Based on the concepts of various discontinuum modelling compiled in this paper, the advanced numerical tools for describing the accurate coupled HM processes of the deep geological repository should be developed.

• Journal of Advanced Navigation Technology
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• v.22 no.1
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• pp.13-19
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• 2018

In this paper, we classified a flight pattern of unmanned aerial vehicle(UAV) which will be operating in UTM system and analyzed its flight pattern by purpose of use. Flight patterns of UAV are sorted into three patterns which are circling, monitoring and delivery. We considered four cases of industry areas using UAV which are agriculture, infrastructure monitoring, public safety & security(p.s.s) and delivery. It is necessary to build a simulation model as a verification tool for applying the flight pattern according to the use of UAV to the real UTM system. Therefore, we propose the simulation model of UAV with updating states over time. We applied simulation to UAV monitoring flight pattern, and confirmed that the flight was done by the given input data. The simulation model will be used in the future to verify that the UAV has various flight patterns and can operate safely and efficiently for the intended use.

• Journal of the Korea Society for Simulation
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• v.8 no.2
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• pp.57-72
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• 1999

With the rapidly increasing complexity of decision-marking or system development in the fields of industry, management, etc., modelling techniques using simulation has become more highlighted. Particularly, the advent of parallel computer systems not only has opened a new horizon of parallel simulation, but also has greatly contributed to the speed-up of the execution of simulation. The implementation of parallel simulation, however, is not a easy job for those who accustomed to the existing computer systems. And it is also necessarily confronted with the problem of synchronization conflict in the process. Thus, how to allow a wider community of users to gain access to parallel simulation while solving synchronization conflicts has become an important issue in simulation study. As a method to solve these problems, this paper is primarily concerned with the implementation of GPSS which is a generally used simulation language for discrete event simulation, onto a parallel computer using C-LINDA. For that, this paper, is to suggest a model and algorithm and to experiment it using a case.

• International Journal of Automotive Technology
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• v.7 no.4
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• pp.459-468
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• 2006

The objective of this paper is the development of the forward-looking dynamic simulation model of a hybrid electric vehicle(HEV) for a fuel economy study. The specification of the vehicle is determined based on two factors, engine peak power to curb weight ratio and specific engine power. The steady state efficiency models of the powertrain components are explained in detail. These include a spark ignition direct injection(SIDI) engine, an integrated starter alternator(ISA), and an infinitely variable transmission(IVT). The paper describes the integration of these models into a forward facing dynamic simulation diagram using the AMESim environment. Appropriate vehicle and driver models have been added and described. The controller was designed in Simulink and was combined with the physical powertrain model by the co-simulation interface. Finally, the simulation results of the HEV are compared with those of a baseline vehicle in order to demonstrate the fuel economy potential. Results for the vehicle speed error and the fuel economy over standard driving cycles are illustrated.

• Journal of the Korean Operations Research and Management Science Society
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• v.10 no.1
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• pp.54-64
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• 1985

This paper deals with analysis on complex and dynamic Primary Health Care (PHC) Systems in rural community to increase understanding of the nature of PHC feedback systems. Because Industrial Dynamics can be very useful for the analysis of such complex and dynamic systems. We used that as a basic tool of Modelling and simulation running. Even If PHC system-models require many assumptions, simulations based on these models can lead decision makers to a better way of problem solving.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.206-211
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• 1998

In audio techniques calculation of digital filters is accelerated considerably by use of wave variables instead of voltages and currents. The suitability of wave variables for digital simulation of power converters was investigated and the results are reported in this paper. The original method is described briefly, modelling of switches and diode rectifiers is presented, examples are given and the features of the method are discussed.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10a
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• pp.315-320
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• 1988

This paper considers modelling and control of ABS(Anti-skid Brake System) which avoids dangerous wheel locking due to excessive brake pressure during the vehicle braking. The brake pressure is controlled by on and off's of solenoid valves via the variation of the wheel circumferential deceleration measured using tacho-sensors. The dynamic model between the brake pressure and the wheel acceleration of a vehicle is mathematically derived. The computer simulation shows that the threshold value of the on-off control is critical to the performance of the ABS.

• Proceedings of the IEEK Conference
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• 2000.11b
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• pp.345-348
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• 2000

In this paper, We described the procedures to generate an input-output buffer information specification (IBIS) model in digital IC circuits. We gives the method to describe IBIS standard I/O for the characteristics of I/O buffer and to represent its electrical characteristics. The parameters of I/O structure for I/O buffer modelling are also referred, and an IBIS model for CMOS, TTL IC, ROM and RAM constructed amounts about 216. This IBIS model can be used to the simulation of signal integrity of high speed circuits in a PCB level.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.102-105
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• 1995

In power system stability analysis, modelling of the synchronous machine is necessary and vary important. In this paper, a synchronous machine is modeled and simulated by using Object-Oriented method. The mathematical equations describing the dynamic behavior of the synchronous machine is represented by block diagram and Objected-Oriented Digital Computer Simulater(ODCS). The developed method is tested for a one-machine-to-infinite-bus system, which is accurate and very useful for a multi-machine system simulation.