• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.2
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• pp.99-105
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• 2011

The magnetic circuit analysis excluding flux loss and fringing effect often gives a result with unignorable error, when compared with real system. But, it is not easy to make a complete magnetic circuit model with the loss effects. This paper introduces a relatively simple method to build the model including the flux loss and fringing effect, in which the paths of leaked flux are simplified in terms of circular arcs and straight lines. After modification of the model, the error of about 36 % in maximum between the magnetic circuit analysis and FEM analysis is reduced to about 7 %.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.1
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• pp.19-25
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• 2003

As a test specimen. an aluminum extruded panel with a dimension of 640 mm$\times$740 mm$\times$40mm is considered. This plate has 9 mm thickness if mass is concerned. Based on the FEM modeling in rigidity. the specimen turns out to be 32 mm and 12 mm thickness In isotropic steel plate. Also, the characteristics of transmission loss on the honeycomb structure have been examined experimentally with reverberation chamber. A honeycomb structure follows mass law in above 800 Hz. In order to improve the noise transmission effect in lower frequency, extra damping treatment is suggested. As a conclusion. the examined honeycomb structure Is designed to Improve the bending rigidity, not for the noise reduction.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.6
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• pp.103-110
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• 1997

A performance prediction method is presented for single(double) suction centrifugal pumps with a review of loss correlations given in the previous open literature. Most of the loss analyses mentioned in the present study are one dimensional and this paper investigates several modeling schemes and shows that a fairly good prediction can be achieved by a proper selection of the most important flow parameters resulting from a mean streamline analysis. Predictions of the trends of total head- capacity and pump efficiency-capacity curves agree well with the experimental data in almost the full range of operating conditions. The prediction method developed through this study can serve as a tool to ensure good matching between parts and it can assist the understanding of the operational characteristics of general purpose centrifugal pumps.

• ETRI Journal
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• v.38 no.6
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• pp.1031-1041
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• 2016

This paper presents millimeter-wave (mmWave) propagation characteristics and channel model parameters including path loss, delay, and angular properties based on 28 GHz and 38 GHz field measurement data. We conducted measurement campaigns in both outdoor and indoor at the best potential hotspots. In particular, the model parameters are compared to sub-6 GHz parameters, and system design issues are considered for mmWave 5G Giga communications. For path loss modeling, we derived parameters for both the close-in free space model and the alpha-beta-gamma model. For multipath models, we extracted delay and angular dispersion characteristics including clustering results.

• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.2537-2540
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• 2001

The purpose of this study is to examine the calculated method of loss characteristics of full-bridge eletronic ballast for 250Watt HID lamps by approximated modeling. These lamps have the most emit effiency and color rendering. Especially, the majority of losses appear to the MOSFET do full-bridge, L of output terminal and driver IC, besides losses occur to the R in the ballast. These losses cause heating and breakage of MOSFET. When HID-lamp arrivals the steady-state, loss of ballast is measured 9% and analyzed value is 8% approximately. Accordingly it is not too much to say that greater part of losses is examined.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.987-989
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• 2005

Axi-periodic analysis using magnetic vector potential is formulated in time harmonic field and applied to the field analysis for the end region of large turbo generator in this paper. By using axi-periodic analysis, the effect of flux shield, one of the structure placed in the end region of large turbo generator to prevent stator end from thermal damage, is studied, and eddy current loss in the flux shield is estimated for operation conditions. 3D FEA is used for the verification of presented analysis method. Because 3D flux distribution can be calculated with 2D modeling, magnetic field showing 3D distribution can be effectively calculated by axi-periodic analysis comparing with 3D FEA.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.3
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• pp.243-247
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• 2005

The Different-volume- V-connection transformer is known as an electric power source that can supply 3-phase electric power and single-phase electric power at the same time. Usually, we use two single-phase transformers that have different volumes. In this paper, we propose the use of a 3-phase 5-leg transformer with the different-volume- V-connection. And, we examine the magnetic properties of the 5-leg core model with the different-volume- V-connection. The magnetic properties of cores with the different-volume- V-connection are compared with those with the delta-connection. In order to express the magnetic anisotropy of the core materials and to calculate the iron loss directly, the two-dimensional vector magnetic property is considered with the E&SS modeling in the simulation.

• Journal of Mechanical Science and Technology
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• v.14 no.8
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• pp.879-890
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• 2000

This study investigates the nonpremixed $H_2/CO$-air turbulent flames numerically. The turbulent combustion process is represented by a reaction progress variable model coupled with the presumed joint probability function. In the present study, the turbulent combustion model is applied to analyze the nonadiabatic flames by introducing additional variable in the transport equation of enthalpy and the radiative heat loss is calculated using a local, geometry independent model. Calculations are compared with experimental data in terms of temperature, and mass fraction of major species, radical, and NO. Numerical results indicate that the lower and higher fuel-jet velocity flames have the distinctly different flame structures and NO formation characteristics in the proximity of the outer core vortex zone. The present model correctly predicts the essential features of flame structure and the characteristics of NO formation in the bluff-body stabilized flames. The effects of nonequilibrium chemistry and radiative heat loss on the thermal NO formation are discussed in detail.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.243-247
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• 2004

Tile development of a porous iron-oxide coated sand filter system can be modelled with the analytical solution of tile transport equation in order to obtain the operating parameters and investigate the mechanism of arsenic removal. The adsorbed amount from the model simulation showed the limitation of adsorption removal during arsenic transport. A loss reaction term in the transport equation plays a role in the mass loss in column conditions, and then resulted into the better model fitting, particularly, for arsenate. Further, the competitive oxyanions delayed the breakthrough near MCL (10 $\mu$g/L) due to the competitive adsorption. This is the reason why arsenate can be strongly attracted in tile interface of an iron-oxide coated sand, and competing oxyanions can occupy the adsorption sites. Therefore, arsenic retention was regulated by non-equilibrium of arsenic adsorption in a porous iron-oxide coated sand media. The transport-limited process seemed to be affect the arsenic adsorption by coated sand.

• The Journal of the Korea Contents Association
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• v.5 no.3
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• pp.201-208
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• 2005

To guarantee the quality of service for user request, we should consider various kinds of things. The important thing of QoS is that response time of service is transparently suggested 'to network users. We can know the response time of service using the information of network latency, system latency, and software component latency, In this paper, we carried out the modeling of network latency and analyzed the effects of packets loss to the network latency, Also, we showed the effectiveness of modeling using the NS-2. This research can help to provide the effective methods in case of SLA(Service Level Agreement) agreement between service provider and user.