• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.33 no.2C
• /
• pp.149-154
• /
• 2008

One of the criteria for designing good LD-STBC is maximizing the mutual information between the transmit and receive signals. In this paper, we propose a construction method of $2^k{\times}2^k$ LD-STBC by selecting the dispersion matrices among the representations of the non-abelian group $G_{m,r}$, of order $2^{k+2}$.

• International Journal of High-Rise Buildings
• /
• v.1 no.4
• /
• pp.301-310
• /
• 2012

Buildings, energy and the environment are key issues that the building professions and energy policy makers have to address, especially in the context of sustainable development. With more tall buildings constructed in China, the impact on energy consumption and carbon emission would be great from buildings (2% increase of carbon dioxide annually between 1971 and 2004). The imperative was to investigate the building energy performance of high-rise in different climate zones and identify the key design parameters that impose significantly influence on energy performance in sustainable building design. Design implications on glazing performance, sizing of the ventilation fans, renewable energy application on high-rise building design are addressed. Combination of effective sustainable building design strategies (e.g., building envelope improvement, daylight harvesting, advanced lighting design, displacement ventilation, chilled ceiling etc.) could contribute more than 25% of the total building energy consumption compared to the international building energy code.

• 한국전산유체공학회:학술대회논문집
• /
• 1999.05a
• /
• pp.199-204
• /
• 1999

Three dimensional numerical analysis for the turbulent reactive flow and radiative heat transfer in the walking beam type of a reheat furnace in POSCO has been carried out by the industrial code FLUENT. Computations an based on the conservation equations of mass, momentum, energy and species with the $k-{\varepsilon}$ turbulence model and mixture fraction/PDF(Probability Density Function) approach for the combustion rate. Radiative heat transfer is computed by the discrete ordinates radiation model in combination with the weighted-sum-of-gray-gas model for the absorption coefficient of gas medium. The predicted temperture distribution in the reheat furnace and energy flow fractions are in reasonable agreement with the measurement data.

• 한국전산유체공학회:학술대회논문집
• /
• 2003.08a
• /
• pp.158-163
• /
• 2003

This paper assesses the two-equation turbulence models available in a commercial code, FLUENT, for heat transfer in a turbulent heated pipe flow. In case of flow under $Re_D=10,000$, Standard $\kappa-\epsilon$ and Realizable $\kappa-\epsilon$ models overpredict the Nusselt number about $20\%$ compared with the experimental correlation, and RNG $\kappa-\epsilon$ model overpredicts about $30\%$ when the two-layer zonal method is employed. When wall function method is adopted, all $\kappa-\epsilon$ models show better predictions. Standard $\kappa-\omega$ and SST $\kappa-\omega$ models have the dependency on the first grid point ($0.3). As Reynolds number becomes high, the predictions of all $\kappa-\epsilon$ and $\kappa-\omega$ models are in a good agreement with the experimental correlation.

• Journal of computational fluids engineering
• /
• v.12 no.4
• /
• pp.38-43
• /
• 2007

Owing to the rapid progress in manufacturing technology of microscale devices, there are active research works in developing microscale propulsion systems. In this study, gas flows in nozzles with size of milli and sub-millimeter are investigated by using a CFD code based on the Navier-Stokes equations. The prediction results were compared with theoretical results of quasi-one-dimensional nozzle flow and experiment data. In general, theoretical values agree very well with the CFD results. However, theoretical values begin to deviate from the CFD and experimental data for relatively small Reynolds numbers and the nozzle shape with rectangular cross section. The primary reason for this discrepancy is due to the existence of the thick boundary layer at the wall in low Reynolds flows.

• Wind and Structures
• /
• v.13 no.6
• /
• pp.487-498
• /
• 2010

When designing structures to the wind action, the variation of the mean wind velocity and turbulence parameters with the height above the ground must be taken into account. This paper presents the numerical simulation results of atmospheric boundary layer (ABL) airflows, in a numerical domain with no obstacles and with a cubic building. The results of the flow characterization, obtained with the FLUENT CFD code were performed using the ${\kappa}-{\varepsilon}$ turbulence model with the MMK modification. The mean velocity and turbulence intensity profiles in the inflow boundary were defined in accordance with the Eurocode 1.4, for different conditions of aerodynamic roughness. The maintenance of the velocity and turbulence characteristics along the domain were evaluated in an empty domain for uniform incident flow and the ABL Eurocode velocity profiles. The pressure coefficients on a cubic building were calculated using these inflow conditions.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 1999.05a
• /
• pp.69-74
• /
• 1999

This paper aims to DNC application of car seat cushion die. DNC systems are consist of CAD(CATIA1, CAM(Z-MASTER, OMEGA) software and CNC milling machine. CAM software is purpose to G-code generation for CNC programming. Then CAM software and CNC milling machine are connect to RS-232-C cable for networking.

• Journal of the Korean Institute of Telematics and Electronics B
• /
• v.32B no.11
• /
• pp.153-162
• /
• 1995

When vector quantization is used in low rate image coding (e.g., R<0.5), the primary problem is the tremendous computational complexity which is required to search the whole codebook to find the closest codevector to an input vector. Since the number of code vectors in a vector quantizer is given by an exponential function of the dimension. i.e., L=2$^{nR}$ where Rn. To alleviate this problem, a multiple shell structure of hypercube feature maps (MSSHFM) is proposed. A binary HFM of k-dimension is composed of nodes at hypercube vertices and a multiple shell architecture is constructed by surrounding the k-dimensional hfm with a (k+1)-dimensional HFM. Such a multiple shell construction of nodes inherently has a complete tree structure in it and an efficient partial search scheme can be applied with drastically reduced computational complexity, computer simulations of still image coding were conducted and the validity of the proposed method has been verified.

• Journal of the Society of Naval Architects of Korea
• /
• v.36 no.4
• /
• pp.28-36
• /
• 1999

An efficient inverse design method based on the MGM(Modified Garabedian-McFadden) method has been developed. The 2-D Navier-Stokes equations are solved for obtaining the surface pressure distributions and coupled with the MGM method to perform the inverse design. The MGM method is a residual-correction technique, in which the residuals are the difference between the desired and the computed pressure distribution. The developed code was applied to several airfoil shapes and the propeller. It has been found that they are well converged to their targeting shapes.

• Steel and Composite Structures
• /
• v.12 no.2
• /
• pp.167-181
• /
• 2012

Ultra high performance cementitious composite material is applied to the design of multifunctional permanent form for bridge pier in this paper. The basic properties and calculating constitutive model of ultra high performance cementitious composite are introduced briefly. According to momental theory of thin-walled shell, the analytical solutions of structural behavior parameters including circumferential stress, longitudinal stress and shear stress are derived for UHPCC thin-walled circular tube. Based on relevant code of construction loads (MHURD of PPC 2008), the calculating parameter expression of construction loads for UHPCC thin-walled circular tube is presented. With geometrical dimensions of typical pier, the structural behavior parameters of UHPCC tube under construction loads are calculated. The effects of geometrical parameters of UHPCC tube on structural behavior are analyzed and the design advices for UHPCC tube are proposed. This paper shall provide a scientific reference for UHPCC permanent form design and UHPCC hybrid structure application.