• Explosives and Blasting
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• v.23 no.1
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• pp.47-54
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• 2005

An explosion modeling technique was developed by using the spherical discrete element code, $PFC^{3D}$, which can be used to model the dynamic stress wave propagation phenomenon. The modeling technique is simply based on an idea that the explosion pressure should be applied to a $PFC^{3D}$ particle assembly not in the form of an external force (body force), but in the form of a contact force (surface force). A test blast was conducted for a RC column, whose dimension was $600\times300\times1800$ in millimeters. The initial velocities of the surface movements were measured to be in the range of $14\~18\;m/s$ with the initiation times of $1.5\~2.0m$. Then the blasting procedure was simulated by using the modeling technique. The particle assembly representing the concrete was made of cement mortar and coarse aggregates, whose mirco-properties were obtained from the calibration processes. As a result, the modeling technique developed in this study made it possible for the burden to move with the velocity of $17\~24\;m/s$, which are slightly higher values compared to those of the test blast.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.4
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• pp.368-373
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• 2015

As a preliminary study for the development of the gas fueled marine engine, prediction of indicated performances was carried out for a spark-ignition engine using commercial software, GT-POWER. The optimized models through a previous study were applied for the simulation of the intake and exhaust systems in a SI engine. The Spark-Ignition Wiebe model was used to calculate the burn rate in the cylinders and the modified Woschni model was used to calculate the heat transfer to the walls. The predicted performances, such as air delivery, cylinder pressures and indicated mean effective pressures under a range of operating conditions showed good agreement with the experiments.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.12 no.1
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• pp.43-49
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• 2007

The methods of physical oceanographic surveys to examine the effect of thermal discharge from nuclear power plants in Korea have been reviewed and a standard guide to the survey is proposed. It is desirable that in situ observation and numerical thermal diffusion modeling are conducted simultaneously to describe the variation in temperature distribution affected by thermal discharge from a power plant because any observation or numerical modeling alone has limits to do so quantitatively. It is suggested that the field observation must be based on the concept of heat budget modeling considering all artificial and natural heat sources/sinks around the power plant. Any results from numerical modeling must reach to a certain statistical significance level to use for a standard temperature distribution. In addition, the development of standard numerical codes is proposed to improve the problems shown in the past numerical circulation and diffusion modelling.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.42 no.4
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• pp.41-46
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• 2005

Acoustic problems in the environment have gained attention due to the noise and vibration contact often in industry as well as life on modem society. Noise is one of safety element in industry, this proves damaging to humans from both a physical and a psychological aspect and so drop working efficiency. Various noises are happened from machines of manufacturing process in PCB industry. This paper present a new approach for subband feedback Active Noise Control (ANC) using Mel scale for headset system in PCB industry. The proposed Mel scale subband algorithm had a performance advantage over the subband algorithm in the noise attenuation and convergence time.

• Journal of the Earthquake Engineering Society of Korea
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• v.16 no.4
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• pp.27-36
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• 2012

The simulation of the field dynamic soil properties for soil modeling in the centrifuge test is important. In this study, the process of soil modeling based on the shear wave velocity profile is developed. From the resonant column test in each confining pressure, the shear wave velocity profile is expected and the modeling condition is determined by comparing it with that in the field. During the dynamic centrifuge test, the bender element test is performed for measuring the in-flight shear wave velocity profile, and the applicability of the proposed method was verified. This modeling method is applied to the centrifuge test of the Hualien Large-Scale Seismic test.

• Tunnel and Underground Space
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• v.23 no.5
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• pp.372-382
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• 2013

Thermal-hydro-mechanical (THM) modeling is a critical R&D issue in the performance and safety assessment of a high-level waste repository. With an $\ddot{A}$sp$\ddot{o}$ prototype repository, its thermal behavior was analyzed and then compared with in-situ experimental data for its validation. A model simulation was used to calculate the temperature distributions in the deposition holes, deposition tunnel, and surrounding host rock. A comparison of the simulation results with the experimental data was made for deposition hole DH-6, which showed that there was a temperature difference of $2{\sim}5^{\circ}C$ depending on the location of the measuring points, but there was a similar trend in the evolution curves of temperature as a function of time. It was expected that the coupled modeling of the thermal behavior with the hydro-mechanical behavior in the buffer and backfill of the $\ddot{A}$sp$\ddot{o}$ prototype repository would give a better agreement between the experimental and model calculation results.

• Journal of Korea Water Resources Association
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• v.54 no.7
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• pp.495-507
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• 2021

With the recent industrial development, accidental pollution in riverine environments has frequently occurred. It is thus necessary to simulate pollutant transport and dispersion using water quality models for predicting pollutant residence times. In this study, we conducted a field experiment in a meandering reach of the Sum River, South Korea, to validate the field applicability and prediction accuracy of RAMS+ (River Analysis and Modeling System+), which is a two-dimensional (2D) stream flow/water quality analysis program. As a result of the simulation, the flow analysis model HDM-2Di and the water quality analysis model CTM-2D-TX accurately simulated the 2D flow characteristics, and transport and mixing behaviors of the pollutant tracer, respectively. In particular, CTM-2D-TX adequately reproduced the elongation of the pollutant cloud, caused by the storage effect associated with local low-velocity zones. Furthermore, the transport model effectively simulated the secondary flow-driven lateral mixing at the meander bend via 2D dispersion coefficients. We calculated the residence time for the critical concentration, and it was elucidated that the calculated residence times are spatially heterogeneous, even in the channel-width direction. The findings of this study suggest that the 2D water quality model could be the accidental pollution analysis tool more efficient and accurate than one-dimensional models, which cannot produce the 2D information such as the 2D residence time distribution.

• Geophysics and Geophysical Exploration
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• v.12 no.1
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• pp.33-40
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• 2009

In field surveys using the dipole-dipole electrical resistivity method, we often encounter negative apparent resistivity. The term 'negative apparent resistivity' refers to apparent resistivity values with the opposite sign to surrounding data in a pseudosection. Because these negative apparent resistivity values have been regarded as measurement errors, we have discarded the negative apparent resistivity data. Some people have even used negative apparent resistivity data in an inversion process, by taking absolute values of the data. Our field experiments lead us to believe that the main cause for negative apparent resistivity is neither measurement errors nor the influence of self potentials. Furthermore, we also believe that it is not caused by the effects of induced polarization. One possible cause for negative apparent resistivity is the subsurface geological structure. In this study, we provide some numerical examples showing that negative apparent resistivity can arise from geological structures. In numerical examples, we simulate field data using a 3D numerical modelling algorithm, and then extract 2D sections. Our numerical experiments demonstrate that the negative apparent resistivity can be caused by geological structures modelled by U-shaped and crescent-shaped conductive models. Negative apparent resistivity usually occurs when potentials increase with distance from the current electrodes. By plotting the voltage-electrode position curves, we could confirm that when the voltage curves intersect each other, negative apparent resistivity appears. These numerical examples suggest that when we observe negative apparent resistivity in field surveys, we should consider the possibility that the negative apparent resistivity has been caused by geological structure.

• The Journal of Engineering Geology
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• v.27 no.4
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• pp.429-438
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• 2017

Monte Carlo N-Particle (MCNP) modeling algorithm based on the Monte Carlo method was used to perform the simulation of neutron logging in order to increase the reliability and utilization of neutron logs applied in geological and resource engineering fields. To perform the simulation using MCNP, we used a realistic three-dimensional configuration of neutron sonde and formation. Validation of the modeling was confirmed by comparing the calibration curves of sonde manufacture with those calculated by MCNP modeling. After the validation, lithology effects, pore fluid effects, borehole diameter change, casing effect, and effects of borehole water level were investigated through modeling experiments. Numerical tests indicate that changes in neutron count ratio according to the lithology were quantitatively understood. In case of a borehole with a diameter of 3 inches, ratio of counting rates was higher than expected to be interpreted as borehole fluid has small effects on neutron logging. Effect of casing was also small in general, particular when porosity increases. Since modeling results above the groundwater level showed a tendency opposite to those below the groundwater level, neutron logs can be used to detect groundwater level. The modeling results simulated in this study for various borehole environments are expected to be used for data processing and interpretation of neutron log.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.7 no.6
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• pp.701-708
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• 2017

The construction cost is estimated based on the drawings at the design stage and constructor will find efficient construction methods for budgeting and budgeting appropriate to the budget. Accurate quantity estimation and budgeting are critical to determining whether the project is profitable or not. However, since this process is mostly performed depending on manpower or 2D drawings, errors are likely to occur and The BIM(Build Information Modeling) program, which can be automated, is very expensive and difficult to apply in the field. In this study, 3D architectural modeling was performed using SketchUp which is a 3D modeling software and suggest a methodology for Quantity Estimation. As a result, 3D modeling was performed effectively using 2D drawings of buildings. Based on the modeling results, it was possible to calculate the difference of the quantity estimation by 2D drawing and 3D modeling. The research suggests that the 3D modeling using the SketchUp and the calculation of the quantity can prevent the error of the conventional 2D calculation method. If the applicability of the research method is verified through continuous research, it will contribute to increase the efficiency of architectural modeling and quantity Estimation work.