• Journal of Biomedical Engineering Research
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• v.21 no.4
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• pp.403-409
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• 2000

This paper is about to simulate the defibrillation situations using 3D FE(finite element) thorax model and describes the effects of three clinical electrodes' positions and size and organ's resistivity used in simulation on the characteristics of current density distribution over myocardium. The model was constructed with a eillipsoidal cylinder for the thorax and the 2D Visible Human images for remains. And, the distributions of current density were computed by a commercial program ANSYS 5.4. The electrical shock of the AP(anterior-posterior ) electrode provided more current flows with heart than the others and that of the LL(lateral-lateral) electrode showed the most uniform current density distribution. However, the electrode size had little effect on the current density distribution. In the evaluation of model's sensitivity to tissue resistivity variation, the variation of the myocardium's resistivity most affected the minimum, average and maximum current densities.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.11
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• pp.1634-1641
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• 2003

In vivo digestion and metabolism trials were conducted with 10 wethers equipped with ruminal, abomasal, and ileal cannulae to evaluate digestion of ensiled broiler litter (EBL), deepstacked broiler litter (DBL), and composted broiler litter (CBL). Wethers were fed a low protein (6.3% CP) basal diet alone or supplemented to 10.3% CP with EBL, DBL, CBL or soybean meal (SBM). All diets were formulated to be isoenergetic (56% TDN, DM basis). Apparent digestibilities of DM, OM, and ADF were not affected (p<0.05) by diet, but digestibility of CP was improved (p<0.05) by N supplementation. Apparent digestibility of CP was lower (p<0.05) for diets supplemented with CBL and DBL than for diets supplemented with SBM and EBL. Ruminal $NH_3$ concentration was 20 to 24 mg/dl at 2 h after feeding litter-supplemented diets compared with 13 mg/dl for SBM. Abomasal N, $NH_3$ N, and nonammonia N flows were increased (p<0.05) by N supplementation, whereas microbial N flow was not influenced (p<0.05) by diet. Compared with SBM and EBL, undegraded dietary CP flow to the abomasum tended to be greater (p<0.1) when wethers were fed DBL and CBLsupplemented diets. Retention of N (g/d) also was greater (p<0.05) due to greater (p<0.05) N intake and lower (p<0.05) urinary N excretion when wethers were fed diets supplemented with litter (especially EBL) vs. SBM. Overall, characteristics of ruminal fermentation and digestion indicated that broiler litter N was utilized efficiently by wethers, but ensiling may be preferable to deepstacking or composting.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.6
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• pp.591-597
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• 2013

Because most existing non-Newtonian models are not suitable for application to the lattice Boltzmann method, theoretical and numerical studies in this regard remain challenging. In this study, the hydrokinetic (HK) model was modified and applied to a 3D sudden contraction-expansion channel flow, and the characteristics of the HK model flow were evaluated to generate non-trivial predictions in three-dimensional strong shear flows. The HK model is very efficient for application to the lattice Boltzmann method because it utilizes the shear rate and relaxation time. However, the simulation would be unstable in a high shear flow field because the local relaxation time sharply decreases with an increase in the shear rate in a strong shear flow field. In the HK model, it may become necessary to truncate the relaxation time and non-dimensional parameter to obtain stable numerical results.

• Journal of Korea Water Resources Association
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• v.52 no.2
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• pp.115-123
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• 2019

The effects of the Froude numbers on turbulent flow patterns downstream of a non-submerged spur dike were investigated in a laboratory flume. Three-dimensional velocities and water depths were measured using Acoustic Doppler Velocimetry and distance sensors under three Froude number conditions ($Fr_d=0.31$, 0.38, and 0.46). The results show that there are marginal differences in the velocity fields downstream of a spur dike due to the change of the Froude number. However, an increase of the Froude number was found to reduce cross-sectional area in the flow and to increase the strength of the jet-like flow. The jet-like flow was observed to displace the location of the maximum turbulence kinetic energy within a cross section toward the inner bank in the transverse direction.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.8
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• pp.1105-1111
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• 2010

The Korea Atomic Energy Research Institutes has been developing the SMART (System integrated Modular Advanced ReacTor), an environment-friendly nuclear reactor for the generation of electricity and to perform desalination. SMART reactors can be exposed to various external and internal loads caused by seismic and coolant flows. The CRDM(control rod drive mechanism), one of structures of the SMART, is a component which is adjusting inserting amount of a control rod, controlling output of reactor power and in an emergency situation, inserting a control rod to stop the reactor. The purpose of this research is performing the analysis of dynamic characteristic to ensure safety and integrity of structure of CRDM. This paper presents two FE-models, 3-D solid model and simplified Beam model of the CRDM in the coolant, and then compared the results of the dynamic characteristic about the two FE-models using a commercial Finite Element tool, ABAQUS CAE V6.8 and ANSYS V12. Beam 4 and beam 188 of simplified-model were also compared each other. And simplified model is updated for accuracy compare to 3-D solid.

• 한국태양에너지학회:학술대회논문집
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• 2012.03a
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• pp.149-152
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• 2012

$Cu(In,Ga)Se_2$ (CIGS) is one of the most promising photovoltaic materials because of large conversion efficiency which has been achieved with an optimum Ga/(In+Ga) composition in $CuIn_{1-x}Ga_xSe_2$ (X~0.3). The Ga/(In+Ga) content is important to determine band gap, solar cell performances and carrier behaviors at grain boundary (GB). Effects of Ga/(In+Ga) content on physical properties of the CIGS layers have been extensively studied. In previous research, it is reported that GB is not recombination center of CIGS thin-film solar cells. However, GB recombination and electron-hole pair behavior studies are still lacking, especially influence of with different X on CIGS thin-films. We obtained the GB surface potential, local current and I-V characteristic of different X (00.7 while X~0.3 showed higher potential than 100 mV on GBs. Higher potential on GBs appears positive band bending. It can decrease recombination loss because of carrier separation. Therefore, we suggest recombination and electron-hole behaviors at GBs depending on composition of X.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.17 no.3
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• pp.129-137
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• 2005

In this study, we developed a model to simulate the interaction between sediment and the overlying water. The model deals with water-sediment interaction in terms of the sedimentation of organic detritus from the pelagic zone into the benthic zone and the release of nutrients occurring in the reverse direction. The model was tested and verified by comparing the predicted release rates of phosphorus from the sediment in Osaka Bay with actual observed values. The results accurately reproduced the seasonal change in release rates. The results well represented seasonal change of the release rates. A long-term prediction of water and sediment quality was performed for the period from 1950 to 1999. Nutrient loads from land and the boundary conditions of 3-D baroclinic flows were season-adjusted. The model accurately reproduced the changing trends in phosphorus, nitrogen, and COD concentrations in Osaka Bay over a long period of time.

• Asian-Australasian Journal of Animal Sciences
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• v.28 no.10
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• pp.1419-1426
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• 2015

This study aimed to investigate the effect of the ratio of non-fibrous carbohydrates to neutral detergent fibre (NFC/NDF) and undegraded dietary protein (UDP) on rumen fermentation and nitrogen metabolism in lambs. Four $Dorper{\times}thin-tailed$ Han crossbred lambs, averaging $62.3{\pm}1.9kg$ of body weight and 10 mo of age, were randomly assigned to four dietary treatments of combinations of two levels of NFC/NDF (1.0 and 1.7) and two levels of UDP (35% and 50% of crude protein [CP]). Duodenal nutrient flows were measured with dual markers of Yb and Co, and microbial N (MN) synthesis was estimated using $^{15}N$. High UDP decreased organic matter (OM) intake (p = 0.002) and CP intake (p = 0.005). Ruminal pH (p<0.001), ammonia nitrogen ($NH_3-N$; p = 0.008), and total volatile fatty acids (p<0.001) were affected by dietary NFC/NDF. The ruminal concentration of $NH_3-N$ was also affected by UDP (p<0.001). The duodenal flow of total MN (p = 0.007) was greater for lambs fed the high NFC/NDF diet. The amount of metabolisable N increased with increasing dietary NFC:NDF (p = 0.02) or UDP (p = 0.04). In conclusion, the diets with high NFC/NDF (1.7) and UDP (50% of CP) improved metabolisable N supply to lambs.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.6
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• pp.8-16
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• 2003

Aerodynamic characteristics over Micro Aerial Vehicle(MAV) in low Reynolds number regime are numerically studied using 3-D unsteady, incompressible Navier-Stokes flow solver with single partitioning method for multi-block grid. For more efficient computation of unsteady flows, this flow solver is parallel-implemented with MPl(Message Passing Interface) programming method. Firstly, MAV wing with not complex geometry is considered and then, we analyze aerodynamic characteristics over full MAV configuration varying the angle of attack. Present computational results show a better agreement with the experimental data by MACDL(Micro Aerodynamic Control and Design Lab.), Seoul National University. We can also find the conceptually designed MAV by MACDL has the static stability.

• Journal of Korea Water Resources Association
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• v.48 no.3
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• pp.233-243
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• 2015

The bimodal flocculation of cohesive sediments in water environments describes the aggregation and breakage process developing a bimodal floc size distribution with dense flocculi and floppy flocs. A two class population balance equation (TCPBE) was tested for simulating the bimodal flocculation by a model-data fitting analysis with two sets of experimental data (low and high turbulent flows) from 1-D flocculation-settling column tests. In contrast to the Single-Class PBE (SCPBE), the TCPBE could simulate interactions between flocculi and flocs and the flocculation mechanism by differential settling in a low turbulent flow. Also, the TCPBE could perform the same quality of simulation as the elaborate Multi-Class PBE (MCPBE), with a small number of floc size classes and differential equations. Thus, the TCPBE was proven to be the simplest model that is capable of simulating the bimodal flocculation of cohesive sediments in water environments and water, wastewater treatment systems.