• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.21 no.11
• /
• pp.983-990
• /
• 2011

This paper investigates active noise control(ANC) of a rectangular cavity using single channel filtered-x least mean square(FXLMS) algorithms to globally reduce the interior noise. To obtain the global reduction of the interior noise, multichannel active control should be incorporated in general. We, however, examined firstly the optimal location of the secondary source that produces a global reduction of the interior noise field using single channel control. We then investigated the frequency characteristics of the reduction to yield the effective frequency band of the active control system. It follows that the secondary source should be located as close to the primary source as possible in order to obtain the global reduction.

• RED RIBBON
• /
• s.54
• /
• pp.10-11
• /
• 2003

얼마 전 성추행 당한 사병이 그 고통을 견디다 못해 자살한 사건이 있었다. 군대라는 밀폐된 공간에서 성범죄가 자행된다는 사실에 온 국민은 경악을 금치못했다. 인권의 사각지대라는 멍에를 벗기 위해 노력하던 군은 또 다시 성범죄라는 큰 짐을 떠안게 되었다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.3 no.3
• /
• pp.197-205
• /
• 1991

A numerical study has been performed to investigate two dimensional natural convection heat transfer in a rectangular enclosure with heat sources of constant temperature at the bottom. Calculations were made for various dimensionless heat source lengths, W/L=0.1-0.5, and positions of heat sources at $Gr=2.57{\times}10^6$, Pr=0.71 and Ks/Kf=28.98. For various positions of heat sources, the maximum local Nusselt numbers generally show X=0.81-0.85 at the bottom and X=0.23 at the top. For various dimensionless heat source lengths, the maximum local Nusselt numbers at the bottom show W/L=0.4 for one heat source, W/L=0.2 for two heat sources with fixed centers, W/L=0.5 for two heat sources with moved centers. Finally the maximum heat transfer at the bottom exhibits in condition of W/L=0.4 for two heat sources with moved centers.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2011.10a
• /
• pp.287-288
• /
• 2011

• Solar Energy
• /
• v.17 no.3
• /
• pp.67-73
• /
• 1997

In order to development of a new wall structure type thermal diode for energy saving, the numerical studies have been performed for natural convection across an rectangular enclosure with the various lengthes of the heat source and sink plate. The governing equations for the two-dimensional, laminar, natural convection process in an enclosure are discretized by the control volume approach which insures the conservative characteristics to be satisfied in the calculation domain, and solved by a elliptic SIMPLE algorithm. The momentum and energy equations are coupled through the buoyancy term.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.10 no.1
• /
• pp.95-107
• /
• 1998

Natural convection and radiation heat transfer in a square enclosure containing absorbing, emitting, and isotopically scattering(participating) media is studied numerically using the finite volume method. Various numerical methods are employed to analyze the radiative heat transfer. However, it is very difficult to choose the proper method. In present study, a finite volume method(FVM) and a discrete ordinates method(DOM) are compared in rectangular enclosure. The SIMPLER algorithm is used to solve the momentum and energy equations. Thermal and flow characteristics are investigated according to the variation of radiation parameters such as optical thickness and scattering albedo. The result shows that the accuracy and the computing time of FVM are better than those of DOM in regular geometry.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.25 no.5
• /
• pp.619-626
• /
• 2001

The present experimental and numerical study investigate flow and natural convection heat transfer characteristics of a composed rectangular-parallelogrammic enclosure with a guide vane. The governing equations for the two-dimensional, laminar, natural convection process in an enclosure are discretized by the control volume approach which insures the conservative characteristics to be satisfied in the calculation domain, and solved by a modified SIMPLE algorithm. The momentum and energy equations are coupled through the buoyancy term. In this results of experimental study, the natural convection heat transfer characteristics was well coincided with conclusions of other earlier experimental researches and numerical analysis.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.7 no.2
• /
• pp.287-297
• /
• 1995

In this study, the geometry consists of a two-dimensional rectangular enclosure with localized heating from below. The size and the location of the heater on the floor has been varied, and one of the vertical walls remains at a low temperature simulating a cold window. The governing equations for momentum, energy and continuity, which are coupled with turbulent equations have been solved using a finite volume method. A low Reynolds number $k-{\varepsilon}$ model has been incorporated to solve the turbulent kinetic energy and the dissipation rate. The heat transfer characteristics and the thermal environmental characteristics of the room have been obtained for various system parameters in a room with a partially heated floor.

• Journal of the Korean Society of Industry Convergence
• /
• v.7 no.4
• /
• pp.391-397
• /
• 2004

This paper presented results of experimental and numerical work for natural convection in a square enclosure by using PIV technique. 2D PIV technique and liquid crystal are employed for velocity and temperature measurement in water. The numerical method used this work is a CFD corde, STAR-CD. The experimental work are compared with these of numerical results.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.23 no.1
• /
• pp.104-113
• /
• 1999

A hybrid spatial differencing scheme for the discrete ordinates method is proposed to predict radiative heat transfer in two-dimensional rectangular enclosures. Since this scheme takes the advantages of the diamond scheme and step scheme and includes the characteristics of medium, more accurate and stable results can be obtained. In its development several spatial differencing schemes are examined to address the effect of numerical smearing (or false scattering). Predictions from the proposed hybrid scheme are compared to those of other schemes for transparent, purely absorbing, purely scattering, or absorbing-emitting-isotropically scattering media. It is found that the proposed scheme predicts stable and less smeared results than others.