• 한국전산유체공학회:학술대회논문집
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• 2005.10a
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• pp.67-74
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• 2005

Fluid flow and heat transfer in rectangular duct system are measured and computed by commercial software of Star-CD for comparison between them. Three rectangular systems are investigated in this study. Those are a rectangular duct with 90 degree bended elbow, a rectangular duct with two branchs, and a circular cylinder in a rectangular duct. But heat transfer is studied only for last system. These investigations show us that the numerical solutions predict satisfactorily design factors (K-factor for the elbowed duct, distributions of flow rates into each branch from a duct, and Nusselt number around circular cylinder) even though there are some disagreements in velocity profiles and turbulent kinetic energy.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.753-758
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• 2000

Heat engine and fluid machinery in the plant have to linked with various ducts network and the corresponding design have to be concerned about effectiveness and stability of system of plant. To optimum control and design system concerning stability, economization, operating effectiveness we have to exact analysis flow properties of a duct applying to fluid machinery, heat exchanger, cooling machine, air conditioning equipment. therefore, it is necessary to research the duct, heat transfer equipment, for increasing overall effectiveness of air conditioning system by suggesting basic data of the duct resulting from organic research. So we can contribute to technical development of the duct. In case of speeding up the flow rate of the duct, lots of wave velocity components are occurred the value of boundary layer resulting from developing the boundary layer at both walls of duct.

• Journal of the Society of Naval Architects of Korea
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• v.43 no.2 s.146
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• pp.236-245
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• 2006

The ventilation performance for the various venting duct arrays has been experimentally compared in the scaled model of the container hold. Most container ships have the ventilation duct system to remove effectively the condensing heat released from container refrigerator. The existing duct system is vertically installed and basically has the number of duct as many as the columns of reefer container stack. In this study, to make up for the weak points having stagnantly hot legions in the centered area of container hold for the present system, the horizontal upward jotting duct system was proposed and proved by temperature rising tests on the scaled model. In this paper, the expected flow regimes and the thermal and hydrodynamic analogies as well as the measured temperature distributions in a hold for various duct types and heat released rates are deeply discussed.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.375-380
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• 2006

Embedded Duct Ventilation System in Ondol is embedded supply duct in Ondol. This system allows heat up outside air to inside temperature with out using heat exchanger and electric heating coiling in winter season. In this research, we measured temperature of inside and surface of Ondol, supply duct, and supply air temperature incorporate embedded duct ventilation system in Ondol in model house($110m^2$) & one room($23m^2$)

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.05b
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• pp.99-104
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• 2011

Daylighting system is an alternative to the energy crisis and environment change. And it is possible improvement system of Architectural Space Environment. Accordingly, it is very useful system. Because Daylight Duct System of Daylighting System gives high performance for its price, distribution rate is very high. But Daylighting Duct System is hard to accurate control. Accordingly, it is difficult to maintain continuously Daylight Environment in Interior Spaces. Lighting Diffusion System has been developed that it is Applying the principle of Reflector and prism diffuser for maximize the efficiency of lighting of Daylight Duct Systems through this study. And then compare lighting performance of Existing System and new Lighting Diffusion System through producing a mock-up. Thus, this study was carried out for the purpose of verification for excellence. It is that installed Each Daylighting Duct System for performance evaluation in a laboratory of width 4m, length 10m, height 2.5m. And illuminance was measured at noon on winter solstice(December 22) under clean sky. The actual measurement result was in the following. Newly developed lighting Diffusion system was measured maximum illuminance 399, minimum illuminance 221, average illuminance 141. Synthetically, daylight factor, uniformity factor and illuminance distribution were improved more than existing system. As a result, it was confirmed that was improved lighting Environment in Interior Spaces.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.535-539
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• 2008

The machinery ventilation system in case of using the window nature ventilation is difficult due to strong outdoor wind pressure is common ventilation measure. increasing height and decreasing economical efficiency problem because of ventilation duct installation is rising and a measure is urgent. The purpose of this study is analysis required height according to each ventilation system and development of ventilation duct system to reducing height and model testing.

• Journal of KSNVE
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• v.4 no.2
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• pp.187-198
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• 1994

This study is to describe the effects of the duct termination conditions conditions upon the active noise attenuation system. The adaptive filtering algorithm using FIR filter is implemented for duct noise attenuation. To avoid the instability caused by the acoustic feedback, two methods are considered. One is to use a compensating FIR filter. The other is to utilize uni-directional detecting microphone and uni-directional control speaker. Experimental results show that the reflections of sound from duct terminations greatly reduce the performance of ANC system. The directionality of detecting microphone and control speaker is a major factor to decide ANC performance. When there are some reflections from both duct terminations, the noise attenuation using finite FIR filter is not enough to model the duct plant. Especially, the reflection from the upstream termination reduces the noise attenuation in the frequencies related to the distance between control speaker and upstream termination. The performance of the noise attenuation is found to be largely enhanced by using uni-directional coupler, both on detecting microphone and control speaker, even if the duct system has an arbitrary termination conditions.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.523-528
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• 2008

The accurate distribution of flow rate has been a very important part to control the air change rate since introduction of house ventilation system. An inappropriate selection of fan due to incorrect prediction of pressure loss in duct brings energy loss. In the previous study the pressure loss of general spiral duct was measured and database was constructed for finding correct loss factors in fitting upper stream. The purpose of this study is to compare and investigate the error range of flow rate by applying T-Method to bilateral symmetry and asymmetry layout of duct. The results of this study are as following. It is demanded to decide accurate size under duct design for house ventilation system. Because the small amount of Flow rate was considered at that time. The error range was 3.17% on case1 and 3.52% on case2. The error range difference was 0.35%.

• The KSFM Journal of Fluid Machinery
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• v.14 no.4
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• pp.45-51
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• 2011

The kimchi refrigerator is the electronic home appliance which is used for the maturing and a custody of the kimchi. In this paper, performance improvement of fan and duct system for kimchi refrigerator has been studied by using a commercial CFD code. In order to achieve a improved fan performance, three-dimensional computational fluid dynamics and the Design of Experiments method have been applied. Additionally, to know the optimized duct inlet shape with the optimized fan, the overall performances were calculated with various duct inlet shapes. The final fan and duct system for kimchi refrigerator showed improved performance in efficiency and total head compared with the existing model.

• The KSFM Journal of Fluid Machinery
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• v.19 no.1
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• pp.18-23
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• 2016

A HVAC(Heating Ventilation and Air Conditioning) is adapted to increase the comfort of the cabin environment for train. The train HVAC duct system has very long duct and many outlets due to the shape of a train set. the duct cross section shape is limited by a roof structure and equipments. Therefore, the pressure distribution and flow uniformity is an important performance indicator for the duct system. In this study, the existing blow down type HVAC duct system for a train was supplemented to improve the flow uniformity by applying a design method combining design of experiment (DOE) with numerical analysis. The design variables and the test sets were selected and the performance for each test set was evaluated using CFD(Computational Fluid Dynamics). The influence of each design variable on the system performance was analysed based on the results of the performance evaluation on the test sets. Furthermore, the optimized model, whose the flow uniformity was improved was produced using the direct optimization(gradient-based method). Finally, the performance of the optimized model was evaluated using numerical analysis, and it was confirmed that its flow uniformity has indeed improved.