• Journal of Energy Engineering
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• v.27 no.4
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• pp.98-102
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• 2018

In order to improve the durability of components in the vehicle engine room, an experiment to improve the air cooling effect of components by installing a cooling duct using intake air aiming at four components, such as generator, battery, ECU and power steel oil, Respectively, experimental results show that the overall component temperature has been reduced, and the reduced temperature difference is in the order of generator, ECU, power steel oil and battery. In order to improve the temperature difference due to these components, it is necessary to optimize the design through the flow analysis in the duct in the future.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.11
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• pp.770-775
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• 2007

Although these days application of heat recovery ventilation and improved kitchen ventilation system came into wide use in mixed-use residential buildings and exclusive residences, there are not enough ventilation systems except the local ventilation of kitchens and rest rooms. It is very important part to regulate and distribute correct air flow rate for controlling air change rate. The purpose of this study is to investigate the application of distributor at house ventilation system by comparing a duct system with out distributor and with distributor. The results of this study are as follows. (1) When using distributor though the size of duct diameter is reduced rapidly, the pressure loss doesn't rise largely. The pressure loss without distributor is 4.08 mmAq, the pressure loss with distributor 4.10 mmAq. (2) To use distributor can reduce materials of duct and secure enough ceiling space by reducing duct diameter. (3) Diameters and air flow paths of distributor on the design stage are important part for accurate air flow rate.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.42 no.3 s.303
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• pp.81-90
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• 2005

When we transmit signals, which are quantized by the vector quantizer (VQ), through noisy channels, the overall performance of the coding system is very dependent on the employed quantization scheme and the channel error effect. In order to design an optimal coding system, the source and channel coding scheme should be jointly optimized as in the channel-optimized VQ. As a suboptimal approach, we may consider the robust VQ (RVQ). In RVQ, we consider developing an index assignment function for mapping the output of quantizers to channel symbols so that the effect of the channel errors is minimized. Recently, a VQ, which can reduce the encoding complexity and is called the sample-adaptive product quantizer (SAPQ), has been proposed. SAPQ has very similar quantizer structure as to the product quantizer (PQ). However, the quantization performance can be better than PQ. Further, the encoding complexity and the memory requirement for the codebooks are lower than the regular full-search VQ case. In this paper, SAPQ is employed in order to design an RVQ to channel errors by reducing the vector dimension. Discussions on the codebook structure of SAPQ and experiments are introduced in an aspect of robustness to noisy channels.

• 연구논문집
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• s.29
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• pp.39-48
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• 1999

This paper deals with the lobby pressurization for smoke control in building fires. A computer program and related modeling technique are presented. The pressure difference between a lobby and a fire area is not able to be same among building floors because an injection fan can not be installed in each floor. The most remote area from the injection fan has therefore the smallest pressure difference if flow areas are not different through all floors. An adjacent floor from the injection fan has possibly too large pressure difference because the most remote lobby must also meet the required pressure difference over the fire area. Moreover this problem will lead to a larger capacity of the fan. It is showed that the fan capacity can be decreased by adjusting the flow area of air supply duct in each floor.

• 한국전산유체공학회:학술대회논문집
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• 2002.10a
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• pp.121-126
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• 2002

Aircraft propulsion systems often use diffusing S-duct to convey air flow from the wing or fuselage intake to the engine compressor, Well designed S-duct should incur minimal total pressure losses and deliver nearly uniform flow with small transverse velocity components at the engine compressor entrance. Reduced total pressure recovery lowers propulsion efficiency and nonuniform flow conditions at the engine face lower engine stall limits. In this study, S-duct which has maximum total pressure recovery and nearly uniform flow profiles at the compressure intake should be found using design optimization methods with 3-dimensional Wavier-Stokes analyses.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.99-104
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• 2006

Accurate flow rate distribution has been become a very important part for controling of air change rate since the introduction of house ventilation system. An inappropriate selection of fan due to Incorrect prediction of friction loss makes waste energy. The purpose of this study is to recognize applicability of T-Method at house ventilation system by comparing experiment with T-method, The result of this study is as follows Flow rate is small amount in a house, so duct size must be accurate. And duct design with Equal Friction Loss Method presented large error range. Equal friction loss method is not fit to applicate small amount air flow rate. T-Method predicts accurate flow rate comparatively in a house ventilation system. Error range was 3.5%.

• Fire Science and Engineering
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• v.31 no.1
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• pp.1-9
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• 2017

This study conducted Testing, Adjusting, and Balancing (TAB), which is a type of field performance evaluation experiment of a zone smoke-control system, at a railway underground transit passage installed with a zone smoke- control system to find problems and improvements for ensuring performance. TAB for the smoke control system was classified into several procedures, such as design data review, duct leakage test, field measurement of the airflow rate, velocity of the fan and duct, and a smoke test. Through the duct leakage test, the system leakage ratio was examined to prove the duct sealing. The iImprovement of the smoke control airflow problems due to the lack of fan static pressure loss was the secured performance. The performance of the smoke control fan was secured by improvements of the smoke control airflow rate problems caused by the loss of static pressure in the intake duct. The smoke test in the smoke control zone confirmed that the damper operating schedule subject was influenced by natural wind or train wind.

• Magazine of korean Tunnelling and Underground Space Association
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• v.13 no.5
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• pp.50-59
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• 2011

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.597-602
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• 2012

Flame deflector is an important plan item for protecting propulsion system model, test facility, and life. This study suggests the way of flame deflector design in test facility evaluating performance of 75 ton and 300ton PSM. The flame deflector height was designed as 30m using a slope way in establishment location of facility. The flame deflector suitability was considered according to the shape of open and closed type. Also the cooling duct was made as modeling in accordance with core and side injection type.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.5
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• pp.497-503
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• 2016

In this study, we formulate an acoustical topology optimization problem to optimally design a partition layout inside the expansion chamber of a muffler. The lower-limit insertion loss value at a target frequency is constrained, and the partition volume is selected as an object function. In this study, we calculate the insertion loss outside the duct, while to determine the noise-attenuation performance, we use the insertion loss value calculated inside the duct or transmission loss value obtained in a previous study. We employ the finite-element model for acoustical analysis, and we determine the transmission of an incident acoustic wave through each finite element using the functions of design variables that change continuously between "0" and "1." The rigid body elements, which totally reflect incident waves, build up partitions. Finally, we compare optimal topologies that depend on the target frequency and the allowed lower-limit value of insertion loss.