• Transactions of the Korean Society of Automotive Engineers
• /
• v.7 no.6
• /
• pp.1-7
• /
• 1999

In this study, the prediction method of coolant flow rates has been developed and applied to an engine and vehicle cooling system. The flow rate passing through each component of the system is very important parameter to evaluate the heat transfer process form the combustion gas to the coolant and the heat rejection process form the radiator /heater to the ambient air. However, the present study reveals that the measurement using the flowmeter fails to give practical flow rates due to its additive resistance. In contrast, the present method which uses the parallel and serial relationship of flow resistance proved to be a good tool to predict the real flow rates. It can be also used to design the cooling system in the incipient stage of engine/vehicle development . The procedure was coded to the computer program so as to use it flexibly and, in the future, to expand it into an independent design tool of the whole cooling system including the heat release and rejection.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.52 no.4
• /
• pp.173-178
• /
• 2003

In this paper, we studied the physical and electrical characteristics of $\textrm{WSi}_{x}$ thin film with respect to the adoption of the DCS (dichlorosiliane) post flow and the variation of deposition temperature. XRD measurements show that as deposited thin film has a hexagonal structure regardless of deposition Process. However, we find that the phase of thin film has changed to a tetragonal structure after the heat treatment at $680^{\circ}C$. Adoption of DCS post flow and increment of deposition temperature result in the increments of Si/W composition ratio. These conditions also result in the increment of sheet resistance by the amount 3.0~4.2$\Omega$/$\square$, but give the tendency in the decrement of stress by 0.27~0.3 E10dyne/$\textrm{cm}^2$. We also find that the contact resistance of word line and bit line interconnection was decreased by the amount 5.33~16.43$\mu$$\Omega$-$\textrm{cm}^2$, when applying DCS post flow and increasing deposition temperature.

• Journal of Biomedical Engineering Research
• /
• v.36 no.6
• /
• pp.264-270
• /
• 2015

A mock circulatory loop system has been developed to construct a simulator for trainees in cardiopulmonary bypass systems or to simulate a test environment for cardiac-assist devices. This paper proposes a computerized mock circulatory loop system whose node is modularized by using a servo control flow regulator to simulate dynamic change of the hemodynamic status. To observe the effect of time-varying resistance, one with hemodynamic properties, the proposed system replicates the planned cross-sectional areas of the outlet of a ventricular assist device in terms of voltage input of a servo valve. The experiment is performed (1) for steady-input commands of selected area sizes and (2) for dynamic commands such as monotonous increase and decrease, and oscillatory functions of the voltage input, and a computer program based on LabVIEW (National Instruments, Austin, USA) processes every measured data and control command to the servo valve. The results show that the pressure and flow at the target points with respect to time-varying resistance match intuitive estimation: the pressure at the outlet and the pressure drop between both sides of the valve increased and the flow at the outlet decreased for increased resistance.

• Korean Journal of Materials Research
• /
• v.1 no.3
• /
• pp.132-138
• /
• 1991

A comparision was made on the influence of BPSG flow temperatures on the electrical properties in submicron CMOS DRAMs containing two BPSG layers. Three different combinations of BPSG flow temperature such as $850^{\circ}C/850^{\circ}C,\;850^{\circ}C/900^{\circ}C,\;and\;900^{\circ}C/900^{\circ}C$ were employed and analyzed in terms of threshold, breakdown and isolation voltage along with sheet resistance and contact resistance. In case of $900^{\circ}C/900^{\circ}C$ flow, the threshold voltage of NMOS was decreased rapidly in channel length less than $0.8\mu\textrm{m}$ with no noticeable change in PMOS and a drastic decrease in breakdown voltages of NMOS and PMOS was observed in channel length less than and equal to $0.7\mu\textrm{m}$ and $0.8\mu\textrm{m}$, respectively. Little changes in threshold and breakdown voltages of NMOS and PMOS, however, were shown down to channel length of $0.6\mu\textrm{m}$ in case of $850^{\circ}C/850^{\circ}C$ flow. The isolation voltage was increased with decreasing BPSG flow temperature. A significant increase in the sheet resistance and contact resistance was noticeable with decreasing BPSG flow temperature from $900^{\circ}C$ to $850^{\circ}C$. All these observations were rationalized in terms of dopant diffusion and activation upon BPSG flow temperature. Some suggestions for improving contact resistance were made.

• The Korean Journal of Community Living Science
• /
• v.24 no.3
• /
• pp.391-397
• /
• 2013

This study was conducted to define the characteristics of the fan according to the bed depth of rough rice for the silo used in South Korea. In this study, the characteristics like air flow resistance and air flow rate of the fan were investigated for an independent blowing system with 1 fan and the serial blowing system with 2 fans. In the experiment, the depth of rough rice was determined by 0, 1, 2, 3.2 and 4.5 m for an independent blowing system and the depth of rough rice was 4.5 m for the serial blowing system. The air flow resistances of the blowing fan and the suction fan in an independent blowing system were 55 mmAq and 88 mmAq respectively. In addition, the air flow resistance of the serial blowing system was 61% lower than the blowing fan and 28% lower than the suction fan of the independent blowing system. The air flow rates of the blowing fan and the suction fan in the serial blowing system were 516 $m^3/min$, 570 $m^3/min$, respectively. The former was 22% higher than the blowing fan while the latter was 29% higher than the suction fan in the independence blowing system. In other words, the serial blowing system was superior to the independent blowing system in blowing characteristics because the air flow rate was lower and air flow resistance was higher than the independent blowing system. However, the fan power consumption of the serial blowing system was more than 100% comparing with the independent blowing system.

• Journal of Korean Society of Forest Science
• /
• v.106 no.4
• /
• pp.424-430
• /
• 2017

With its rapid velocity and wide deposition, debris flow is a natural disaster that causes loss of human life and destruction of facility. To design effective debris barriers, impact force of debris flow should be first considered. Debris flow velocity is one of the key features to estimate the impact force of debris flow. In this study, we conducted small-scale flume experiments to analyze flow characteristics of debris flow, and determine flow resistance coefficients with different slope gradients and sediment mixtures. Flow velocity significantly varied with flume slope and mixture type. Debris flow depth decreased as slope increased, but difference in depth between sediment mixtures was not significant. Among flow resistance coefficients, Chezy coefficient ($C_1$) showed not only relatively highest goodness of fit, but also constant value ($20.19m^{-1/2}\;s^{-1}$) regardless the scale of debris flow events. The overall results suggested that $C_1$ can be most appropriately used to estimate flow velocity, the key factor of assessing impact force, in wide range of debris flow scale.

• Journal of the Korea Convergence Society
• /
• v.11 no.9
• /
• pp.175-180
• /
• 2020

In this study, the freight vehicles were modelled and the flow analysis on the existence or non-existence of a cargo container and the wind deflector were carried out. Based on the driving speed of 100 km/hr, at all models A, B and C, the highest flow rate was shown between 58 m/s and 59 m/s at the top of the model shape. All models A, B and C showed the highest pressure of air resistance between 652Pa and 671Pa at the front of the model geometry. The maximum pressure of model A is considered to be the smallest, with the least flow resistance to speed compared to models B and C. Therefore, it can be seen that model A has an advantageous condition for air resistance in terms of fuel costs. Unlike model B which causes the rapid flow resistance at the cargo compartment, model C can be found to flow a little more smoothly on the streamlined wind deflector. So, the flow air at a streamlined shape is considered to be more advantageous in terms of air resistance than at angular shape. By applying the research analysis result on the air flow in driving according to a cargo container and the wind deflector, it is seen that this study is adequate at the practical efficient design and aesthetic convergence.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.28 no.2
• /
• pp.238-246
• /
• 2004

This paper reports an experimental study around a module about forced air flow by blower (35${\times}$35${\times}$6㎣) in a portable personal computer model(200${\times}$235${\times}$10㎣). Experimental report is to know three data to investigate thermal resistance, adiabatic wall temperature and visualized fluid flow around the module by combination of the moving number and the arrangement method of blower. The channel inlet flow velocity has been varied between 0.26, 0.52 and 0.78㎧, and input power ( $Q_{p}$) to the module is 4W. To investigate thermal resistance. the heated module is mounted on two boards(110${\times}$110${\times}$1.2㎣, k=20.73, 0.494W/ $m^{\circ}C$) in parallel-plate channel to forced air flow. The temperature distribution were visualized by heated module on acrylic board(k=0.262W/ $m^{\circ}C$) using liquid crystal film. Fluid flow around the module were visualized using particle image velocimetry system.

• Journal of Navigation and Port Research
• /
• v.34 no.6
• /
• pp.417-422
• /
• 2010

In this study, the resistance performances of barge are analyzed by model tests and computation using CFD to investigate the flow characteristics around a barge in still water. The model tests are carried out in infinite depth in Inha Technical College Circulation Tank to observe the resistance and the numerical simulations based on VOF(Volume of Fluid) method are performed to analyze the flow around the barge. We have selected two barge models to investigate the flow characteristics according to the different type of barges. The experiments are carried out with the models from 5kts to 10kts(designed speed 7kts) considering the effect of adverse and favorable current. The numerical simulations are performed to analyze the flow and resistance characteristics of barge in the full loaded condition with the target speed and compared with the experimental data to confirm the reliability of the numerical method. The result was that the difference of resistance with 25% occurred at low speed and EHP increased rapidly from 7kts.

• Journal of the Society of Naval Architects of Korea
• /
• v.48 no.6
• /
• pp.544-551
• /
• 2011

The internal flows of moonpool usually causes huge added resistance on drillships, and those are very complex to analyze. Therefore, not only experimental approaches but also numerical simulations are required for better investigations when dealing with the hydrodynamic problems of moonpool. In the present research, numerical simulations are used to find out why the resistance increases by moonpool on a running drillship. That is, the three-dimensional numerical simulations and model tests are carried out to examine the characteristics of internal flow and added resistance by changing the section of the moonpool in both longitudinal and transverse directions. Finally, based on the present studies, an optimized shape of the moonpool is suggested, which effectively reduces added resistance, and that is confirmed with three-dimensional numerical simulations and model tests.