• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1893-1896
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• 2005

Cutting force and face roughness have the largest influence on precision of a structure or processing efficiency in cutting processing. Thus cutting force model and face roughness model are necessary for this interpretation. In this paper, tool path model and face roughness model which consider the blade number of a tool and a revolution speed of tool and workpiece in the worm processing using side milling cutter are presented. This model was used to forcast the cusp. Experimental results show that the predicted cusp coincides with experimental one.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.05a
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• pp.236-239
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• 2003

The spent fuel slitting device is an equipment developed in order to feed UO$_2$pellet to the dry pulverizing/mixing device. In this study, we have compared and analyzed the handling method of the slitting and that of the pellet and hull, processing time, separating time for 20kgHM, the number of blades, on the existing slitting device using in DUPIC, and spent fuel management technology research and test facility. Also, we have compared and analyzed about an advantage and weak point, designing and producing, processing, establishment, operation, maintenance about the vertical and horizontal slitting device. Based on these results, we have developed the vertical slitting device. By using the results, we have enhanced the slitting processing time(over 40%)in comparison with DUPIC device, and it will is effectively applied to available data for designing and producing of the hot test facility.

• 유체기계공업학회:학술대회논문집
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• 1998.12a
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• pp.57-63
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• 1998

The performance of a centrifugal fan depends on the dimensional parameters of impeller, such as the inlet and exit diameter, area ratio, relative flow angles to the blade, and number of blades. These design parameters, however, are inter-related, so it is very difficult to identify the effect of each parameter to the fan performance. In this experimental study the effect of the design parameters on the performance of a small centrifugal impeller being used for vacuum cleaners are investigated. Total 30 shrouded impellers with 120mm diameter were tested and the results were non-dimensionalized to compare their performance.

• 한국전산유체공학회:학술대회논문집
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• 2001.10a
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• pp.58-62
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• 2001

Aparallel computing environment was constructed based on Windows 2000 operating system. This cluster was configured using Fast-Ethernet system to hold up together the clients within a network domain. For the parallel computation, MPI implements for Windows such as MPICH.NT.1.2.2 and MP-MPICHNT.1.2 were used with Compaq Visual Fortran compiler which produce a well optimized executives for x86 systems. The evaluation of this cluster performance was carried out using a preconditioned Navier-Stokes code for the 2D analysis of a compressible and viscous flow around a compressor blade. The parallel performance was examined in comparison with those of Linux clusters studied previously by changing a number of processors, problem size and MPI libraries. The result from the test problems presents that parallel performance of the low cost Fast-Ethernet Windows cluster is superior to that of a Linux cluster of similar configuration and is comparable to that of a Myrinet cluster.

• 한국전산유체공학회:학술대회논문집
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• 2001.05a
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• pp.121-126
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• 2001

An accelerating flow field through a compressor cascade is studied numerically by unsteady computational simulation. The two-dimensional Navier-Stokes equations for compressible flow is used for the study of unsteady high incidence angle flow, with preconditioning scheme to cover the wide range of Mach number and $\kappa-\omega$ model for the turbulent viscous flow analysis. A DCA(double circular arc) compressor blade is accelerated artificially in this study to understand the unsteady effect by comparing the present results with the existing steady-state experimental and computational results. Also, the accelerating flow field during the starting phase of gas turbine is studied with actual experimental data for the understanding of flow field and performance characteristics at off-design condition.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1066_1067
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• 2009

Wind power is one of most promising renewable energy. The output capacity of large wind turbine has been increased for off-shore application. Number of installation of small wind turbine also has been increased for the stand-alone and off-grid application of remote area and recently small wind turbine equipped with lamp on the pole is used for street lamp. Maximum wind energy must be extracted by wind turbine within rated wind speed. Power must be controlled to protect the system such as blade, generator, and power system above the rated wind speed. In this paper, small wind power system of 800W rating for battery charging is implemented and output power control by furling system is verified at wind tunnel test.

• Transactions of the Korean Society of Mechanical Engineers
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• v.7 no.2
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• pp.153-160
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• 1983

The flows in an axial flow turbomachine are calculated numerically in the two sets of flow surfaces of H-S and B-B surfaces assuming that the flow is axisymmetric. The calculation is performed by regarding the governing equations as the quasi-Poisson's equations and using the finite element method for the flow regions divided into triangular elements. The results of numerical calculation agree comparatively well with the experimental results and it has been found that the distribution of an axial velocity component at the rotor exit is not necessarily uniform under the influences of the inlet guide vanes and the front shape of the hub even if the rotor is designed by the free-vortex theory. Also it has been found that the existence of the optimum value of the blade number can be estimated from the results of calculation of deviation angles at rotor exit if we consider the viscous flow-loss, and that the flows of B-B surfaces are affected very sensitively by the degree of satisfaction of Kutta condition.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.4
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• pp.464-471
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• 2011

We tried to analyze sound field of the interior of housing installed with an impeller using the Boundary Element Method (BEM) with the Kirchhoff-Helmholtz integral equation. In order to increase the accuracy of our analysis, reverse engineering technology, which has been developed in recent years. We measured and treated geometrical data with 3D scanning of the practical research object. After modeling by the reverse engineering, we analyzed variation of the BPF as adding vibration frequency and variation of the sound field of the interior of housing by changing the number of impeller blades. We also tried an analysis of free degree variation. Then, we proposed the analysis accuracy and noise reducing method by analysis result.

• International Journal of Aeronautical and Space Sciences
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• v.8 no.2
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• pp.44-53
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• 2007

A three-dimensional viscous flow solver has been developed for the prediction of the aerodynamic performance of hovering helicopter rotor blades using unstructured hybrid meshes. The flow solver utilized a vertex-centered finite-volume scheme that is based on the Roe's flux-difference splitting with an implicit Jacobi/Gauss-Seidel time integration. The eddy viscosity are estimated by the Spalart- Allmaras one-equation turbulence model. Calculations were performed at three operating conditions with varying tip Mach number and collective pitch setting for the Caradonna-Tung rotor in hover. Additional computations are made for the UH-60A rotor in hover. Reasonable agreements were obtained between the present results and the experiment in both blade loading and overall rotor performance. It was demonstrated that the present vertex-centered flow solver is an efficient and accurate tool for the assessment of rotor performance in hover.

• ALGAE
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• v.30 no.3
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• pp.207-216
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• 2015

Caloglossa species occurs in freshwater streams around Southest Asia. We report it from 2 different riverine sites in Kerala, India. Tetrasporangiate plants were observed in field collections from the Periyar River and Chalakkudy River. The Chalakkudy isolate did not reproduce in culture but the Periyar isolate developed abundant tetrasporangial sori in culture. Many spores were discharged and most were abortive, but some germinated normally, sporelings forming male gametophytes with numerous spermatangial sori and females with many procarps, viable carposporophytes and some nonfunctional (no carpospores) pseudocystocarps. Some carpospores germinated forming new tetrasporophytes. Molecular evidence (28S rDNA and rbcL) placed the Indian specimens close to C. beccarii and C. fluviatilis. Considering the freshwater habitat and morphology of vegetative thalli (blade shape, rhizoid arrangement, and number of rhizoid filament per cell), the Indian specimens should be assigned to C. beccarii.