• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.9 no.1
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• pp.14-22
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• 1997

The position of propeller fan from duct inlet is one of basic parameters for the design of propeller fan. To investigate the effect of its position on fan characteristics, the inlet flow fields and relative flow angles were measured by a 5-hole pitot tube. The experimental results indicate that the ratio of radial flow introduced from propeller circumference to total inlet flow increases with the increase of propeller distance from duct inlet. When fan operates without duct, the total flow rate and the radial flow ratio are higher than those of any other positions of propeller relative to duct inlet. The radial flow ratio decreases as a flow coefficient and the propeller distance decrease. Therefore the front flow fields can be adjusted in some extent by varying the propeller distance according to a fan loading. The inlet flow angles are decreasing a little as a rotational speed and the propeller distance decrease. In the present case it was judged that the deviation angle of outlet flow became negative owing to a flow separation near a trailing edge.

• Journal of the Korea Convergence Society
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• v.11 no.5
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• pp.159-164
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• 2020

In this study, the flow analysis of air in the inner side of vehicle due to the position on inlet port of air at car was carried out. Under the comfortable condition as the inlet port in which the air flows, it was possible to confirm that the inlets became the upper and middle sides or the forward side of the vehicle. If the air flow is not evenly distributed within the vehicle, the lower position of the vehicle is the lowest condition among all conditions. The results of this study will help to keep the inner state of the vehicle pleasant by adjusting the location of the inlet to suit the passenger's taste or situation. The design and analysis results of this study can be effectively applied at adjusting the location of the inlet at car. By applying the flow analysis according to the inlet port of air at car, this paper is seen as the convergence study that conforms to aesthetic design.

• Journal of Power System Engineering
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• v.17 no.1
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• pp.58-63
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• 2013

The aerodynamic performance of double inlet sirocco fan is strongly dependent upon the design factors of impeller and scroll. In this paper, the change of scroll size was adopted to investigate the aerodynamic performances of double inlet sirocco fan and indoor PAC. Especially, a scroll expansion angle and a cut-off clearance ratio were considered to change the scroll size. In addition, the installation depth between double inlet sirocco fan and indoor PAC was considered. As a result, the total pressure efficiency of double inlet sirocco fan shows about 62%~73% according to the change of scroll expansion angles. Moreover, the flowrate performance of indoor PAC is the best at the condition of a scroll expansion angle of 8°, an installation depth of 15 mm and a cut-off clearance ratio of 8%.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.456-459
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• 2008

The purpose of this paper is to examine the aerodynamic characteristics of three hypersonic configurations including pure liftbody configuration, pure waverider configuration and liftbody integrated with waverider configuration. Hypersonic forbodies were designed based on these configurations. For the purpose to integrate with ramjet or scramjet, all the forebodies were designed integrated with hypersonic inlet. To better understand the forebody performance, three dimensional flow field calculation of these hypersonic forebodies integrated with hypersonic inlet were conducted in the design and off design conditions. The computational results show that waverider offer an aerodynamic performance advantage in the terms of higher lift-drag ratios over the other two configurations. Liftbody offer good aerodynamic performance in subsonic region. The aerodynamic performance of the liftbody integrated with waverider configuration is not comparable to that of pure waverider in the terms of lift-drag ratios and is not comparable to that of pure liftbody in subsonic. But the liftbody integrated with waverider configuration exhibit good lateral-directional and longitudinal-directional stability characteristics. Both pure waverider and liftbody integrated with waverider configuration can provide relatively uniform flow for the inlet and offer good aerodynamic characteristics in the terms of recovery coefficient of total pressure and uniformity coefficient.

• Nuclear Engineering and Technology
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• v.53 no.1
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• pp.93-102
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• 2021

The analysis of the fluid flow characteristics in reactor pressure vessel is an important part of the hydraulic design of nuclear power plant, which is related to the structure design of reactor internals, the flow distribution at core inlet and the safety of nuclear power plant. The flow distribution and mixing characteristics in the pressurized reactor vessel for the 1000MWe advanced pressurized water reactor is analyzed by using Computational Fluid Dynamics (CFD) method in this study. The geometry model of the full-scaled reactor vessel is built, which includes the cold and hot legs, downcomer, lower plenum, core, upper plenum, top plenum, and is verified with some parameters in DCD. Under normal condition, it is found that the flow skirt, core plate holes and outlet pipe cause pressure loss. The maximum and minimum flow coefficient is 1.028 and 0.961 respectively, and the standard deviation is 0.019. Compared with other reactor type, it shows relatively uniform of the flow distribution at the core inlet. The coolant mixing coefficient is investigated with adding additional variables, showing that mass transfer of coolant occurs near the interface. The coolant mainly distributes in the 90° area of the corresponding core inlet, and mixes at the interface with the coolant from the adjacent cold leg. 0.1% of corresponding coolant is still distributed at the inlet of the outer-ring components, indicating wide range of mixing coefficient distribution.

• Journal of ILASS-Korea
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• v.26 no.2
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• pp.96-103
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• 2021

In order to improve the overall efficiency and meet the emission regulations of boiler systems, the heat exchanging methods between inlet air and exhaust gas have been used in boiler systems, named as the waste-heat-recovery condensing boiler. Recently, to further improve the overall efficiency and to reduce the NOx emission simultaneously, the concept of the water injection into the inlet air is introduced. This study suggests the models for the optimized design parameters of water injection for waste-heat-recovery condensing boilers and performs the analysis regarding the water injection amount and droplet sizes for the optimized water injection. At first, the required amount of the water injection was estimated based on the 1^st law of thermodynamics under the assumption of complete evaporation of the injected water. The result showed that the higher the inlet air and exhaust gas temperature into the heat exchanger, the larger the amount of injected water is needed. Then two droplet evaporation models were proposed to analyze the required droplet size of water injection for full evaporation of injected water: one is the evaporation model of droplet in the inlet air and the other is that on the wall of heat exchanger. Based on the results of two models, the maximum allowable droplet sizes of water injection were estimated in various boiler operating conditions with respect to the residence time of the inlet air in the heat exchanger.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.10
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• pp.1294-1299
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• 2000

The combustion characteristics have been investigated to develop the 50 kW-class gas turbine combustor. The combustor design program was developed and applied to design this combustor. The combustion air which has the temperature of 45, 200, $300^{\circ}C$ were supplied to combustor for elucidating the effect of inlet air temperature on CO, NOx emissions and flame temperature. The exit temperature and NO were increased and CO was decreased with increasing inlet air temperature. Also, the effect of equivalence ratio was considered to verify the combustor performance. The emissions of CO and NO with inlet air temperature can be analyzed qualitatively by measuring the temperature inside the combustor. The combustion performance with fuel schedule was evaluated to get the informations of the starting and part loading process of gas turbine. The combustion was stable above the equivalence ratio of 0.18. The pattern factor which is the important parameter of combustor performance was satisfied with the design criterion. Consequently the combustor was proved to meet the performance goal required for the target gas turbine system.

• Journal of Mechanical Science and Technology
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• v.20 no.10
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• pp.1590-1606
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• 2006

Slider bearings are widely applied in mechanical systems, where the design needs cover increased load capacity, lowered friction and power consumption and creative designs. This work is governed to perform a parametric characterization, by generating a novel structure on the upper slider surface, which can formally be expressed in micro-machined wavy-form, where the individual and combined influences of various structural design parameters and boundary conditions, on the performance records, are also evaluated. Computations put forward that the contribution of the wave amplitude on power loss values is highly dependent on the level of inlet pressure; higher amplitudes are determined to increase power loss in the lowest inlet pressure case of 1.01, whereas the contrary outcome is determined in the higher inlet pressure cases of 3.01 & 5.01. Designing the slider bearing system, based on optimal load capacity, produced the optimum wave number ranges as 10-45, 7-11 and 5-8 for the pad inclinations of $5^{\circ},\;4^{\circ}$ and $3^{\circ}$ respectively.

• Journal of the Semiconductor & Display Technology
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• v.20 no.4
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• pp.134-140
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• 2021

This study investigates the flow efficiency and temperature based on flow path shape. Five models are designed to the no flow path, one flow path, two flow path, three flow path, add inlet flow path and add interior space gradient. Results show that two flow model(add inlet flow path and add interior space gradient), It was confirmed that model(add inlet flow path) is the optimal shape for coolant heat transfer, and model(add interior space gradient) is the optimal shape for coolant flow, demonstrates optimal design among the five models. The results of this study can be utilized to efficiently control the coolant flow through various types of flow paths.

• Journal of Energy Engineering
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• v.22 no.2
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• pp.226-236
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• 2013

The heat distribution and internal flow from the efficiency of actual reformer and specification variation, using the computer simulation and experiment about the steam methane reforming reaction which uses the high temperature reformer. Reaction model from steam refoemer uses the steam response model developed by Xu & Froment.As result we supposed the chemical react Steam Reforming(SR), Water Gas Shift(WGS), and Direct Steam Reforming(DSR) from the inner high temperature reformer dominates the response has dissimilar response. According to result of steam methane reforming reaction exam using high temperature reformer, we figured out when Steam Carbon Ratio(SCR) increase, number of hydrogen yield increases but methane decreases. When comparing and examining between design with one inlet and two inlet, result came out one inlet design is more outstanding at thermal distribution and internal flow, hydrogen yield in one inlet design than two inlet design.