• Journal of Advanced Marine Engineering and Technology
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• v.26 no.2
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• pp.248-255
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• 2002

Miller cycle was studied and analyzed by engine performance simulation to achieve very low fuel consumption and to meet the IMO NOx regulation on a medium speed diesel engine. Based on the performance simulation results the intake valve closing time for HYUNDAI HiMSEN 6H21/32 engine was set at 0deg.ABDC(After Bottom Dead Center). Also, the simulation results indicated that significant NOx reduction could be achieved with low reduction of fuel consumption. The performance simulation investigated the effect of compression ratio and turbocharger on fuel consumption and NOx concentration in combination with Miller cycle. The results indicated a significant reduction of fuel consumption with keeping NOx concentration. The results of performance simulation were compared with measured data to verify simulation results. The comparison showed the maximum error was 2.34% in exhaust temperature. Also, the experimental result showed that improvement in BSFC(Brake Specific Fuel Consumption) was 5.8g/kwh with keeping NOx level similar to simulation result.

• Journal of the Korean Society of Safety
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• v.8 no.2
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• pp.23-29
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• 1993

In this study, the method of deciding simulation test conditions is developed by computer program compared to actual vehicle test as accurately as possible. These results of analytical test conditions are conformed by simulation test using the brake dynamometer by comparison with test results of actual vehicle. Results of simulation test by these analytical results show good agreement with the vehicle test results. The analytical simulation test conditions provide the input data to brake dynamometer which follows : - each test inertia corresponding to braking deceleration - test condition of input control : brake line pressure - test condition of output control : braking torque

• International Journal of Automotive Technology
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• v.6 no.4
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• pp.351-357
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• 2005

Development of a real-time simulation model for high-speed and multibody tracked vehicles is difficult because they involve hundreds of highly nonlinear equations. In the development of a reliable tracked vehicle model for real-time simulation, it is helpful to use an off-line tracked vehicle model developed by considering all the degrees of freedom of each element. This paper presents a step-by-step procedure for the development of a real-time simulation model based on the off-line tracked vehicle model. The road input data, Profile IV, is used for the real time simulation and simulation results are compared with vehicle test results obtained in the military test field. It is noted that the simulation results are quite close to the test results.

• Nuclear Engineering and Technology
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• v.55 no.4
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• pp.1287-1299
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• 2023

A new Monte-Carlo-based computer program (RDS-BASIC) is developed to simulate the transport of energetic ions in pure matter. This computer program is utilizing an algorithm that uses detailed numerical solutions for the classical scattering integral for evaluating the outcomes of the binary collision processes. This approach is adopted by several prominent similar simulation programs and is known to provide results with higher accuracy compared to other approaches that use approximations to shorten the simulation time. Furthermore, RDS-BASIC simulation program contains special methods to reduce the displacement energy threshold of surface atoms. This implementation is found essential for accurate simulation results for sputtering yield in the case of very low energy ions irradiation (near sputtering energy threshold) and also successfully solve the problem of simultaneously obtaining an acceptable number of atomic displacements per incident ions. Results of our simulation for several irradiation systems are presented and compared with their respective TRIM (SRIM-2013) and the state-of-the-art SDTrimSP simulation results. Our sputtering simulation results were also compared with available experimental data. The simulation execution time for these different simulation programs has also been compared.

• International Journal of Air-Conditioning and Refrigeration
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• v.11 no.4
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• pp.159-169
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• 2003

Five two-phase closed loop thermosyphons (TLTs) specially designed and constructed for the present study are one small scale loop, two medium scale loops (MSLI and MSLII) and two large scale loops (LSLI and LSLII). Two simulation models based on thermal resistance network, lumped and sectorial, are presented. In the Lumped model, the evaporator section is dealt as one lumped boiling section. Whereas, in the Sectorial model, all possible phenomena which would occur in the evaporator section due to the two-phase boiling process are considered in detail. Flow regimes, the flow transitions between flow regimes and other two-phase parameters involved in two-phase flows are carefully analyzed. In the present study, the results of two different simulation models are compared with experimental results. The comparisons showed that the simulation results by the Lumped model and by the Sectorial model did not show any partiality for the model used for the simulation. The simulation results according to the correlations show the various results in the large different range.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.2
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• pp.170-180
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• 2000

The equation which is related to TXV performance was investigated. On the basis of this equation, the TXV simulation program was developed. Results of the developed TXV simulation program were proven by the experiment on the influence of pressure difference between TXV entrance and exit and equalizing pressure. Simulation results show very good agreement with experimental results, the RMS error between them was 1.83%. The capillary tube simulation program was made by the basic equation of fluid dynamics. Results of this program were proven by data which were experimented previously. The RMS error between simulation results and experimental results was 4.13% .

• International Journal of Automotive Technology
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• v.6 no.3
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• pp.277-283
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• 2005

Formability simulation of automotive panels at early design phases can reduce product and tooling development time and cost. However, for the simulation to be effective in leading the design process, fast and reliable results should be achieved with limited design definition and minimum modeling effort. In this paper, nonlinear finite element analysis is used to develop an automated process for the formability simulation of automotive body panels at early design phases. Due to the limited design definition at early design phases, the automated simulation process is based on the plane strain analysis for selected number of typical sections along the panel. Therefore, an entire panel can be analyzed with few sections. The state of plane strain can be easily induced, during simulation through symmetry and applied boundary conditions that simplify the modeling process. To study the reliability and effectiveness of the developed simulation process, the analytical results are compared with measured results of production automotive body side panels. The comparison demonstrates that the developed simulation process is reliable and can be effective for analyzing sheet metal formability, in early vehicle development phases.

• Journal of the Korean Society of Visualization
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• v.4 no.1
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• pp.8-13
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• 2006

Fire simulation has been developed for decades to analyze fire cases and provide a tool to study fundamental fire dynamics and combustion. There are three way of fire simulation which are a full scale simulation, an experimental simulation and a computational simulation. In case of a full scale simulation, because a higher cost, a higher risk, more efforts are needed, a demand for it has been decreased. But recently a demand for an experimental simulation and a computational simulation has been increased. A computational simulation has several advantages; lower cost, short period, many case studies, more visual results, a quantitative result and etc. FDS(Fire Dynamics Simulator) which has been developed in BFRL(Building and Fire Research Laboratory), NIST(National Institute of Standards and Technology) is a popular world wide code for fire simulation. Lack of accurate predictions by the model could lead to erroneous conclusions with regard to fire safety. All results should be evaluated by the informed judgment of the qualified user.

• Tribology and Lubricants
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• v.32 no.1
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• pp.9-17
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• 2016

Contact between solid surfaces is one of the most important factors that influence dynamic behavior in micro/nanoscale. Although numerous theories and experimental results on contact behavior have been proposed, a thorough investigation for nanomaterials is still not available owing to technical difficulties. Therefore, molecular dynamics simulation was performed to investigate the contact behavior of nanomaterials, and the application of conventional contact theories to nanoscale was assessed in this work. Particularly, the contact characteristics of cylindrical nanowires were examined via simulation and contact theories. For theoretical analysis, various contact models were utilized and work of adhesion, Hamaker constant and elastic modulus those are required for calculation of the models were obtained from both indentation simulation and tensile simulation. The contact area of the cylindrical nanowire was assessed directly through molecular dynamics simulation and compared with the results obtained from the theories. Determination of the contact area of the nanowires was carried out via simulation by counting each atom, which is within the equilibrium length. The results of the simulation and theoretical calculations were compared, and it was estimated that the discrepancy in the results calculated between the simulation and the theories was less than 10 except in the case of the smallest nanowires. As the result, it was revealed that contact models can be effectively utilized to assess the contact area of nanomaterials.

• KIEAE Journal
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• v.15 no.5
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• pp.95-105
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• 2015

Purpose: This paper presents a framework development for BIM (Building Information Modeling)-based OOPM (Object-Oriented Physical Modeling) for Building Thermal Simulation. The framework facilitates decision-making in the design process by integrating two object-oriented modeling approaches (BIM and OOPM) and efficiently providing object-based thermal simulation results into the BIM environment. Method: The framework consists of a system interface between BIM and OOPM-based building energy modeling (BEM) and the visualization of simulation results for building designers. The interface enables a BIM models to be translated into OOPM-based BEM automatically and the thermal simulation from the created BEM model immediately. The visualization module enables the simulation results to be presented in BIM for building designers to comprehend the relationships between design decisions and the building performances. For the framework implementation, we utilized the Modelica Buildings Library developed by the Lawrence Berkeley National Laboratory as a thermal simulation solver. We also conducted an experiment to validate the framework simulation results and demonstrate our framework. Result: This paper demonstrates a new methodology to integrate BIM and OOPM-based BEM for building thermal simulation, which enables an automatic translation BIM into OOPM-based BEM with high efficiency and accuracy.