• Journal of KIBIM
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• v.8 no.2
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• pp.41-50
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• 2018

The current study focused on the utilization of building information modeling (BIM) data in steel-frame structures, which help to reduce project durations because they employ prefabricated structural members that are assembled on-site. In addition, a business process model was proposed using BIM data collected during the preconstruction, structural steel fabrication, and on-site construction phases of an actual steel-frame project. The ultimate expectation is that BIM data support at each phase, as well as the increased understanding among project participants, will result in an increase in project management productivity. The results from the current study are summarized as follows: To implement a BIM capable of application to steel-frame projects and data utilization, existing theories were studied to develop the construction project steps, both generally into the preconstruction (A1), steel fabrication (A2), and on-site construction phases, (A3) and specifically into 19 BIM-applicable phases. Based on the derived BIM-applicable phases, the model elements of the BIM object were identified, and the shortcomings of existing steel-frame projects were ameliorated, resulting in an improved data flow model. Moreover, for the proposed BIM data flow to progress efficiently, the BIM specialist needs to be well-acquainted with the phase-specific three-dimensional (3D) model output, and the infrastructure to construct an error-free 3D model must be provided. Based on the actual construction example, the BIM data utilized steel-frame projects - via production reports, clash checks, two-dimensional (2D) drawings, four-dimensional (4D) simulations, and 3D scanning - to make cooperation and communication among participants easier.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.571-575
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• 2012

하구역에서의 대표적인 수리특성인 염수쐐기현상에 대한 정확한 이해는 하구역 수질 및 환경관리 측면에서 필수적인 사항이다. 본 연구에서는 정상염수쐐기 경계층 거동에 대한 실험적 연구결과와 3차원 전산유체역학 프로그램인 FLOW-3D를 이용한 수치모의 결과를 비교해봄으로써 염수쐐기현상에 대한 3차원 수치모형의 적용성을 살펴보았다. FLOW-3D를 이용하여 실험장치의 수로구간을 구성하고 경계조건으로 염수의 수위와 담수의 유량을 입력하였으며 밀도차를 두어 이층류가 발생하도록 모의하였다. 모의결과를 통해 시간평균농도와 표준편차를 무차원화하여 단면별 연직분포를 알아보고 각 단면을 중첩하여 경계층의 거동을 살펴보았으며 염수쐐기길이와 염수심을 무차원화하여 밀도프루드수의 변화에 따른 염수쐐기형상을 살펴보았다. 그리고 각 결과를 기 수행된 실험결과와 비교해 보았다.

• Nuclear Engineering and Technology
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• v.32 no.3
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• pp.214-226
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• 2000

In an effort to assess the performance of KAERI's coupled 3D kinetics - system T/H code, MARS/MASTER, Exercise III of the OECD main steam line break benchmark is solved. The analysis model of the reference plant, TMI-1 - a 2772 MWth B&W plant, consists of three major components: a core neutronics model involving 241$\times$28 neutronic nodes, a vessel 3D T/H model consisting of 374 hydrodynamic volumes, and a 1D system T/H model containing 157 hydrodynamic volumes. The results show that there is a significant amount of flow mixing occurring in the upper and lower plenum regions and the core power distribution evolves to a highly localized shape due to the presence of a stuck rod, as well as the asymmetric flow distribution. It is judged that MARS/MASTER properly captures these drastic 3-dimensional effects. Comparisons with other results submitted to OECD confirm the accuracy of the MARS/MASTER solution.

• Journal of Biomedical Engineering Research
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• v.18 no.2
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• pp.187-196
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• 1997

The three-dimensional flow analysis using the finite volume method is presented to compare the steady flow characteristics of blood with those of blood substitutes such as water and aqueous polymer solution in an idealized double branching model. The model is used to simlllate the region of the abdominal aorta near the celiac and superior mesenteric branches. Apparent viscosities of blood and the aqueous Separan solution are represented as a function of shear rate by the Carreau model, Water and aqueoiu Separan AP-273 500wppm solution are frequently used as blood substitutes in vitro experiments. Water is a typical Newtonian fluid and blood and Separan solution are non-Newtonian fluids. Flow phenomena such as velocity distribution, pressure variation and wall shear stress distribution of water, blood and polymer solution are quite different due to differences of the rheological characteristics of fluids. Flow phenomena of polymer solution are qualitatively similar to those of blood but the phenomena of water are quite different from those of blood and polymer solution. It is recommended that a lion-Newtonian fluid which exhibits very similar rheological behavior to blood be used in vitro experiments. A non-Newtonian fluid whose rheological characteristics are very similar to those of blood should be used to obtain the meaninylll hemodynamic data for blood flow in vitro experiment and by numerical analysis

• Journal of Korea Water Resources Association
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• v.45 no.2
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• pp.229-242
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• 2012

This study presents a physical habitat modeling of adult Zacco platypus in a reach of the Dalcheon Stream located downstream of the Goesaan Dam. CASiMiR model is used to estimate habitat suitability index based on the fuzzy logic. Results are compared with those from River2D model, which uses habitat preference curve for habitat suitability index. Hydraulic data simulated by River2D are used as input data for CASiMiR model after verification against field measurements. The result shows that the habitat suitability of the adult Zacco platypus is maximum around the riffle area located upstream of the bend. CASiMiR and River2D estimate the maximum weighted usable areas at the discharge rates of 7.23 $m^3/s$ and 9.0 $m^3/s$, respectively. Overall comparison of the two models employed in this study indicates that CASiMiR model overestimates the weighted usable area by 0.3~25.3% compared with River2D model in condition of drought flow (Q355), low flow (Q275), normal flow (Q185), and average-wet flow (Q95).

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.18 no.4
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• pp.338-347
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• 2006

A small hydro-power plant using the seawater used as the cooling (circulated) water and discharged is under construction. The bigger size of the small hydro-power plant, the better in order to maximize the efficiency and the electric power. The optimal size, however, should be determined in the constraints of the channel un-disturbed range. The water level change should be checked in detail based on the hydraulic behaviour. In this study, the FLOW3D model, three-dimensional flow model, is setup using the flow measurement data in the effluent discharge channel and the flow pattern changes due to the small hydro-power plant construction are predicted by the model. The plant construction makes the increasing of the water level, and the water level in the upstream of the channel weir is increased 65 cm from 4.32 m to 4.97 m, in the condition of the design discharge $156m^3/s$ and the movable weir height of the hydro-power plant 3.8 m.

• Journal of Biosystems Engineering
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• v.32 no.5
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• pp.309-315
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• 2007

This study was performed to develop a simulation model of circulating concurrent-flow rice dryer. The simulation model consists of drying model, tempering model and crack prediction model. The drying and tempering models were developed based on mathematical analysis, and the crack prediction model was developed by thin layer drying tests. Rice drying tests were done with three replications by use of a pilot scale dryer of holding capacity of 700 kg. Experimental values for moisture content, rice temperature, rice crack, and drying energy were compared with predicted values by simulation model. The RMSEs of predicted moisture contents were ranged from 0.5807% (d.b.) to 1.1951% (d.b.). and the coefficients of determination were 0.9688 to 0.9812. The RMSEs of predicted rice temperatures at the exit of the drying chamber were 1.83 to $3.81^{\circ}C$ and the coefficients of determination were 0.8834 to 0.9482. The results for moisture contents and rice temperatures showed very good relationships between predicted values and experimental values. The RMSEs of predicted value of crack ratio were 0.4082 to 0.7967% and the coefficients of determination were 0.8742 to 0.9547.

• Journal of the Korean Institute of Navigation
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• v.24 no.3
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• pp.123-132
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• 2000

In order to improve the ship maneuverability, It is important to estimate precisely the hydrodynamic coefficients of added mass forces acting on a ship especially in shallow waters, and simple methods for predicting such hydrodynamic forces Is also very desirable. In the previous paper using 3-Dimension potential flow theory, it has been demonstrated that potential calculation is available to estimate added mass coefficients. The present work is aimed at the suggestion of the simplified formulas for predicting the translation and lateral motion of added mass coefficients in shallow water. So, 3-D potential flow theory is also used to calculate the added mass coefficients in deep and shallow waters for Series 60 model which has 5 different kinds of block coefficients (0.6-0.8), SR196 model and T/S HANNARA. After some series computation, simplified formulas for Predicting the added mass force in shallow waters is suggested based on the computation results of Series 60 model. The formulas consist of the combination of principal dimensions and the water depth; d/B, Cb, d/H. The predicted results are compared with the Computation results for SR196 model and T/S HANNARA. The precision of predicted results by simplified formulas are good enough for the practical use. (d/B : draft-Breadth ratio, d/H draft-Water depth ratio, Cb : Block coefficients).

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.56 no.3
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• pp.230-237
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• 2020

In order to design a diesel engine system and predict its performance, it is necessary to analyze the gas flow of the intake and exhaust system. A gas flow analysis in three-dimensional (3D) format needs a high-resolution workstation and enormous time for analysis. Therefore, the method of characteristics (MOC) was used for a gas flow analysis with a fast calculation time and a low-resolution workstation. An experiment was conducted on a single cylinder diesel engine to measure pressure in cylinder, intake pipe and exhaust pipe. The one-dimensional (1D) gas flow was analyzed under the same conditions as the experiment. The engine speed, valve timing and compression ratio were the same conditions and the intake pressure was inputted as the experimental results. Bent pipe such as an exhaust port that cannot be realized in 1D was omitted. As results of validation, the cylinder pressure showed accuracy, but the exhaust pipe pressure exhibited inaccuracy. This is considered as an error caused by the failure to implement a bent pipe such as an exhaust port. When analyzed in 3D, calculation time required 61 hours more based on a model of this study. In the future, we intend to implement a bent pipe that cannot be realized in 1D using 3D and prepare a method to supplement reliability by using 1D-3D coupling.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.8
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• pp.1046-1055
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• 2000

The flow and thermal phenomena in flat tubes of radiator are analyzed numerically. To predict the characteristics of heat transfer and pressure drop, the flow analysis program for three-dimensional complex geometry is developed, which adopted an non-staggered grid system and Cartesian velocities as dependent variables of the momentum equations. Using the developed program, the effect of tube specifications on the heat transfer characteristics is investigated for various flat tubes. From this study, the following results are obtained; (1) For the same hydraulic diameter($D_h{\doteq}5.2$mm), the Nusselt numbers of three basic modeis(D, J, and H-model) are 8.71, 8.92, and 10.58, respectively, and the pressure drops of D-, J-, and H-model are predicted as $-3.08{\times}10^{-2}\;Pa,\;-3.12{\times}10^{-2}\;Pa,\;and\; -3.98{\times}10^{-2}$ Pa, (2) In case of the same flat tube specification, the fins must be brazed at upper tube surface because the heat is more vividly transferred. Therefore, it is found that the H- model is the most effective tube as a heat exchanger and these results are used as a fundamental data for the design of tube.