• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.5
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• pp.1435-1442
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• 2014

This study presented numerical simulations of smooth-bed flows in the rectangular open-channel using the source code by OpenFOAM. For the analysis of the turbulent flow, Large Eddy Simulations were carried out and the dynamic sub-grid scale model proposed by Germano et al. (1991) is used to model the residual stress term. In order to analyze the coherent structure, the uw quadrant method proposed by Lu and Willmarth (1973) is used and the contribution rate and the fraction time of the instantaneous Reynolds stress are obtained in the Reynolds stress. The results by the present study are analyzed and compared with data from previous laboratory studies and direct numerical simulations. It is found that the contribution rate of the ejection events is larger than that of sweep events over the buffer layer in the open-channel flow over the smooth bed, however, the frequency of the sweep event is higher than that of the ejection events.

• Journal of Digital Contents Society
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• v.15 no.2
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• pp.197-207
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• 2014

Many people are now enjoying mobile games using various smartphone platforms. However, we have to develop games separately for each smart device platforms so far. Cocos2d-x, a game development framework is released to solve this problem. As a multiplatform version of the existing Cocos2d, Cocos2d-x can make one source code run on various platforms. It is an open software that is able to be used by everyone, and when using it, mobile games can be developed easily based on C++ and OpenGL. In this paper, we implemented a PC laboratory decorating game application, named ILove501, using Cocos2d-x. The 501 is a room number of our PC lab. ILove501 includes an educational feature of solving quizzes in order to highlight positive effects of game. For implementation of a multiplatform game, ILove501 was developed in Windows and iOS environment at the same time, and we verified the results of the execution by porting on a variety of devices such as Android, iPhone, iPad and Galaxy Tab.

• Geomechanics and Engineering
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• v.21 no.5
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• pp.401-411
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• 2020

The paper describes the influence of pile reinforcement on the stability of the slope behaviour, and the exploitation of the results of in situ measurements will be conducted. In the second part, a 2D numerical modelling will be conducted by using the finite element code PLAXIS2D; in order to validate the proposed modelling approach by comparing the numerical results with the measurements results carried out on the slides studied; to study the effect of positioning of piles as a function of the shear parameters of the supported soil on the behaviour of the soil. For various shear strength of the soil a row of pile position is found, at which the piles offer the maximum contribution to slope stability. The position of piles is found to influence the safety factor in granular soil whereas it shows a slight influence on the safety factor in coherent soil. The results also indicate that the ideal position for such stabilizing piles is in the middle height of the slope. Comparison of results of present study with literature from publication: indicated that to reach the maximum stability of slope, the pile must be installed with L_x/L ratio (0.37 to 0.62) and the inclination must be between 30° to 60°. Even, after a certain length of the pile, the increasing will be useless. The application of the present approach to such a problem is located at the section of PK 210+480 to 210+800 of the Algerian East-West Highway.

• Structural Engineering and Mechanics
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• v.66 no.5
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• pp.569-582
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• 2018

Effects of crack separation, bridge area, on the tensile behaviour of concrete are studied experimentally and numerically through the Brazilian tensile test. The physical data obtained from the Brazilian tests are used to calibrate the two-dimensional particle flow code based on discrete element method (DEM). Then some specially designed Brazilian disc specimens containing two parallel cracks are used to perform the physical tests in the laboratory and numerically simulated to make the suitable numerical models to be tested. The experimental and numerical results of the Brazilian disc specimens are compared to conclude the validity and applicability of these models used in this research. Validation of the simulated models can be easily checked with the results of Brazilian tests performed on non-persistent cracked physical models. The Brazilian discs used in this work have a diameter of 54 mm and contain two parallel centred cracks ($90^{\circ}$ to the horizontal) loaded indirectly under the compressive line loading. The lengths of cracks are considered as; 10 mm, 20 mm, 30 mm and 40 mm, respectively. The visually observed failure process gained through numerical Brazilian tests are found to be very similar to those obtained through the experimental tests. The fracture patterns demonstrated by DEM simulations are mostly affected by the crack separation but the tensile strength of bridge area is related to the fracture pattern and failure mechanism of the testing samples. It has also been shown that when the crack lengths are less than 30 mm, the tensile cracks may initiate from the cracks tips and propagate parallel to loading direction till coalesce with the other cracks tips while when the cracks lengths are more than 30 mm, these tensile cracks may propagate through the intact concrete itself rather than that of the bridge area.

• Journal of ILASS-Korea
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• v.21 no.4
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• pp.184-194
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• 2016

Many industrial processes require reliable temperature measurements in harsh environments with high temperature, dust, humidity, and pressure. However, commercially-available conventional temperature measurement devices are not suitable for use in such conditions. This study thus proposes a reliable, durable two-color radiation thermometer (RT) for harsh environments that was developed by selecting the appropriate components, designing a suitable mechanical structure, and compensating environmental factors such as absorption by particles and gases. The two-color RT has a simple, compactly-designed probe with a well-structured data acquisition system combined with efficient LabVIEW-based code. As a result, the RT can measure the temperature in real time, ranging from 300 to $900^{\circ}C$ in extremely harsh environments, such as that above the burden zone of a blast furnace. The error in the temperature measurements taken with the proposed two-color RT compared to that obtained using K-type thermocouple readouts was within 6.1 to $1.4^{\circ}C$ at a temperature range from 200 to $700^{\circ}C$. The effects of absorption by gases including $CO_2$, CO and $H_2O$ and the scattering by fine particles were calculated to find the transmittance of the two wavelength bands of operation through the path between the measured burden surface and the two-color probe. This method is applied to determine the transmittance of the short and long wavelength bands to be 0.31 and 0.51, respectively. Accordingly, the signals that were measured were corrected, and the true burden surface temperature was calculated. The proposed two-color RT and the correction method can be applied to measure temperatures in harsh environments where light-absorbing gases and scattering particles exist and optical components can be contaminated.

• Progress in Medical Physics
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• v.28 no.3
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• pp.77-82
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• 2017

We proposed the objective ROC analysis method based on the setting of threshold value for evaluation of single photon emission computed tomography (SPECT) image. This proposed ROC analysis method uses the quantification computational threshold value to each signal on the SPECT image. The SPECT images for this study were acquired by using Monte Carlo n-particle extended simulation code (MCNPX, Ver. 2.6.0, Los Alamos National Laboratory, USA). The basic SPECT detectors and specific water phantom were realized in the simulation, and we could get the simulation results by the simulation operation. We tried to analyze the reconstructed images using threshold value application based objective ROC method. We can get the accuracy information of reconstructed region in the image. This proposed ROC technique can be helpful when we have to evaluate the weak signal for the NM image. In this study, the proposed threshold value based computational ROC analysis method can provide better objectivity than the conventional ROC analysis method.

• Tunnel and Underground Space
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• v.10 no.4
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• pp.506-515
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• 2000

A lot of underground construction projects have been conducted by economical, social and military purposes in Korea for the last three decades. As a result, magnificent amount of data were obtained from geological site investigations, laboratory and field tests, design and field monitoring. But up to now, these valuable informations were neither systematically stored nor utilized efficiently resulting in a great loss of time and money. In this study, a database system named GeoINFO was developed using Microsoft Access 97 for management of informations which can be obtained from underground construction. The developed database system is especially designed to cover three major types of underground facilities-tunnels, underground storages and rock slopes and has multi-layered tree structures for data input. The system also has a unique indexing system for efficient data search using Visual Basic code.

• Fire Science and Engineering
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• v.13 no.4
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• pp.20-29
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• 1999

This paper describes the smoke filling process of a fire field model based on a self-developed SMEP(Smoke Movement Estimating Program) code to the simulation of fire induced flows in the two types of atrium space containing a ceiling heat flux. The SMEP using PISO algorithm solves conservation equations for mass, momentum, energy and species, together with those for the modified k- epsilon turbulence model with buoyancy term. Compressibility is assumed and the perfect gas law is used. The results of the calculated upper-layer average temperature and smoke layer interface height has shown reasonable agreement compared with the zone models. The zone models used are the CFAST developed at the Building and Fire Research Laboratory NIST U.S.A. and the NBTC one-room of FIRECALC developed at CSIRO, Australia. The smoke layer interface heights that are important in fire safety were not as sensitive as the smoke layer temperature to the nature of ceiling heat flux condition.

• Journal of Biosystems Engineering
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• v.35 no.1
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• pp.15-20
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• 2010

Tractor PTO output and fuel consumption rate under the korean paddy and various paddy operations were measured and analyzed, in which all the measurements were accomplished by the OECD tractor test codes and the collected information will be utilized for defining tractor energy efficiency class and its test methods. Tractor PTO performance tests were conducted under full-load, part-load and various engine RPMs with part-load at the engine laboratory, while the paddy operations were dry land plowing, wet and dry land rotary tilling and wet land preparation under various soils. As a whole, the rated tractor outputs were ranged from 17% to 100% in the various tillage and land preparation operations, however, the loads for the paddy operations of 1,700 to 2,000 rpm were very close to the OECD tractor load distribution thus it would be appropriate to adopt OECD tractor test codes to measure energy consumption efficiency of tractor.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.7
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• pp.549-557
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• 2008

Despite of the laminar-turbulent transition region co-exist with fully turbulence region around the leading edge of an airfoil, still lots of researchers apply to fully turbulence models to predict aerodynamic characteristics. It is well known that fully turbulent model such as standard k-model couldn't predict the complex stall and the separation behavior on an airfoil accurately, it usually leads to over prediction of the aerodynamic characteristics such as lift and drag forces. So, we apply correlation based transition model to predict aerodynamic performance of the NREL (National Renewable Energy Laboratory) Phase IV wind turbine. And also, compare the computed results from transition model with experimental measurement and fully turbulence results. Results are presented for a range of wind speed, for a NREL Phase IV wind turbine rotor. Low speed shaft torque, power, root bending moment, aerodynamic coefficients of 2D airfoil and several flow field figures results included in this study. As a result, the low speed shaft torque predicted by transitional turbulence model is very good agree with the experimental measurement in whole operating conditions but fully turbulent model(${\kappa}-\;{\varepsilon}$) over predict the shaft torque after 7m/s. Root bending moment is also good agreement between the prediction and experiments for most of the operating conditions, especially with the transition model.