• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.10
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• pp.21-26
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• 2016

This study evaluates the magnitudes and distributions of contact tangential forces with the swaging depth of punch acting at the contact surfaces between a rotor core slot and a Cu bar during a sequential rotor core swaging process. The effects of the core slot shape on the magnitudes and distributions of the total contact forces were investigated to improve the productivity of the rotor core swaging process. Parametric elastic-plastic numerical analyses were performed using simplified two-dimensional cyclic symmetric plane strain models to evaluate the contact force distributions at the contact surfaces. The numerical analysis results show that the total contact tangential forces increased by about 55% with the adjacent Cu bar swaging process. The length of the core slot is a dominant factor in the core slot design as result of the increased total contact tangential forces during the swaging process of the rotor core.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.8
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• pp.375-381
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• 2002

A rigorous analysis of a broad wall slot array is presented. The slot is longitudinal and offset from the center line in the rectangular waveguide. Pertinent integral equations are developed, taking into account finite wall thickness. The mothed of moment with entire basis function is used to solve a pair of coupled-integral equations, derived from the electromagnetic boundary conditions using modified Green's function, to find the tangential electric field on the upper and lower surfaces of the slot. Numerical results for resonant length and scattering parameters of the slots are Presented over a range of offset. Computed results are compared with experimental result.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.7
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• pp.869-875
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• 2012

In the past decades, extensive studies on convection heat transfer on internal flow have been conducted by using high specific surface area, by increasing heat transfer coefficient and swirl flow, and by improving the transport properties. In this study, we applied a tangential slot swirl generator to improve heat transfer in a horizontal circular copper tube. The Al-Mg particles (approximately $100{\mu}m$ to $130{\mu}m$) were employed for this experimental work. The copper tube was heated uniformly by winding a heating coil with a resistance of 9 ohm per meter for heat transfer. Using Al-Mg particles, experiments were performed in the Reynolds number range of 5,000 to 13,130, with and without swirl. Experimental data transfers or comparisons between Nusselt numbers with and without swirl along the test tube and Reynolds numbers are presented. The Nusselt number is improved by increasing Reynolds numbers or swirl intensities along the test tube.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.6
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• pp.870-879
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• 2000

An experimental investigation is conducted to improve a slot film cooling system which can be used for the cooling of gas turbine combustor liner. The tangential slots are constructed of discrete holes with different injection types which are the parallel, vertical, and combined to the slot lip. The investigation is focused on the coolant supply systems of normal-, parallel-, and counter-flow paths to the mainstream direction. A naphthalene sublimation technique has been employed to measure the local heat/mass transfer coefficients in a slot with various injection types and coolant feeding directions. The velocity distributions at the exit of slot lip for the parallel and vertical injection types are fairly uniform with mild periodical patterns with respect to the hole positions. However, the combined injection type increases the nonuniformity of flow distribution with the period equaling twice that of hole-to-hole pitch due to splitting and merging of the ejected flows. The secondary flow at the lip exit has uniform velocity distributions for the parallel and vertical injection types, which are similar to the results of a two-dimensional slot injection. In the results of local heat/mass transfer coefficient, the best cooling performance inside the slot is obtained with the vertical injection type among the three different injection types due to the effect of jet impingement. The lateral distributions of Sh with the parallel- and counter-flow paths are more uniform than the normal flow path. The averaged Sh with the injection holes are $2{\sim}5$ times higher than that of a smooth two-dimensional slot path.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2000.11a
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• pp.416-419
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• 2000

A narrow slot in the broad wall of a rectangular waveguide is analysed using a Spatial Network Method[1] which takes account of the waveguide wall thickness. In essence, SNM is used to solve arbitrary shape and materials constant, derived from maxwell's equations to find the tangential electric fields on the upper and lower surfaces of the slot. In this paper, applying to the offset and length[2] which yield a zero equivalent shunt susceptance, analysing single and 4 array slot antenna. The current of the transient analysis shows each the times. Analysed result of SNM is verified by the method of moment and HFSS.

• Proceedings of the KIEE Conference
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• 2000.11c
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• pp.591-593
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• 2000

A narrow slot in the broad wall of a rectangular waveguide is analysed using a Spatial Network Method[1] which takes account of the waveguide wall thickness. In essence, SNM is used to solve arbitrary shape and materials constant, derived from maxwell's equations to find the tangential electric fields on the upper and lower surfaces of the slot. In this paper, applying to the offset and length[2] which yield a zero equivalent shunt susceptance, analysing single and 4 array slot antenna. The current of the transient analysis shows each the times. Analysed result of SNM is verified by the method of moment and HFSS.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.6
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• pp.1251-1258
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• 1997

Generally, it is very important to study selective coupling between cavities of the filter structure using multimode cavity resonator. In this paper, we have manufactured 5-pole bandpass filter(BPF) using dual and triple-mode cavity resonator. To do so, we have derived the formulas for coupling coefficient about coupling between TE-modes from TM/TE-mode's tangential and lognitudinal field intensities each other. To implement the Chebyshev response, the intercabity slot combining dual-mode and triple-mode is designed to couple one H-field of TE-mode parallel to slot plate. In this paper, specially it is derived the formulas for T $E_{11p}$-mode from TE-modes, and determined after obtaining location and size of intercabity slot from the equation. In this ppaer, based on this result, we designed and implmented teh bandpass filter operated at the center frequency of 14.5GHz with a Chebyshev response. For the manufactured cavity filter, dual-mode and triple-mode cavity are resonted by two orthogonal T $E_{113}$-modes, and by two orthogonal T $E_{113}$-modes and one T $M_{012}$-mode, respecitively. The 2-stage 5-pole BPF proposed in this paper has the insertion loss of -2.32dB, the reflection loss of -15dB in the passband, and the out-or-rejection of -67dB.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2365-2372
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• 2011

The Cogging Torgue is non-uniform torgue in motor which causes noise and vibration to synchronous motors such as BLDC motor, and regardless of load current, is generated by the interaction between permanent magnet rotor and stator slot which is the force of tangential direction that tends to move into the position where the magnetic energy of motor system is minimal. such Cogging Torgue shall be considered in design stage since it is the main factor of motor's noise and vibration. Understanding that Cogging Torgue is generated by the interaction between relatively low stage harmonic flux density gab of permanent magnet rotor and steel slot of stator. This study proposes the method if reducing Cogging Torgue using response surface method which is a kind of design if experiment.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.2
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• pp.272-281
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• 2009

The effect of swirl on the flow characteristics in a sudden expansion tube was examined experimentally by using 3D PIV(particle image velocimetry) to capture the velocity profiles. The swirling flow of water through a sudden 1:2 axisymmetric expansion has previously been studied experimentally within a horizontal round tube. A kind of tangential slot is used as a swirl generator for swirling flow and a honey comb is used for without swirl flow. The work with the swirl and without swirl results are compared to each other at the same Reynolds number. Liquid crystal was employed to measure temperature profiles and heating coil used for heat transfer with and without swirl flow. And then the Nusselt number ratoes(Nu/Nudb) are calculated along the test section.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.52-57
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• 2000

STD11 is one of difficult-to-cut materials and its cutting characteristic data is not built enough. A bad cutting condition of it leads to low productivity of die and mould, so it is necessary to evaluate the machining characteristics of STD11. In this paper, the relations of the geometry of ball-end mill and mechanics of machining with it are studied. The helix angle of ball-end mill varies according to a location of elemental cutting edge in the cutting process are difficult to calculate accurately. To calculate instantaneous cutting forces, it is supposed that the tangential, radial and axial cutting force coefficients are functions of elemental cutting edge location. Elemental cutting forces in the x,y and z direction are calculated by coordinate transformation. The total cutting forces are calculated by integrating the elemental cutting forces of engaged cutting edge elements. This model is verified by slot and side cutting experiments of STD11 workpiece which was heat-treated to HRC45.