• 한국산학기술학회논문지
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• 제17권10호
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• pp.21-26
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• 2016

산업체에서 널리 사용되고 있는 유도전동기의 회전자를 제작하기 위하여 rotor core slot에 Cu bar를 열박음(shrinkage fit)작업으로 고정한 후 bar 표면을 punch로 원주방향으로 순차적으로 1.5~3mm 압입(swaging)작업시 rotor core slot과 bar 접촉면에 작용하는 contact tangential force의 크기와 분포를 단순화된 2차원 plane strain 해석모델을 사용하여 각각의 압입조건에 대하여 평가하였으며 또한 생산성 향상을 고려한 rotor core slot 설계시 slot 형상에 따른 접촉력 분포를 평가하여 rotor core slot 설계시 필요한 정보를 제공하고자 수치해석적인 방법을 사용하여 parametric study를 수행하였다. 이러한 탄소성 수치해석 결과 1) rotor core 압입작업시 bar 접촉면에 작용하는 contact force는 소성변형이 먼저 발생하는 bar 상부에 크게 작용하며 2) 순차적인 rotor core 압입작업시 bar 접촉면에 작용하는 total contact force는 바로 인접한 bar에 대한 압입작업에 의해서만 영향을 받으며 그 영향으로 약 55% 정도 total contact force가 증가하며 3) 생산성을 고려하여 rotor core를 설계하는 경우에 contact force를 증가시키기 위해서는 core slot의 폭보다 길이를 길게 하는 것이 바람직하다는 사실을 알 수 있었다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제51권8호
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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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• 제36권7호
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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.

• 대한기계학회논문집B
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• 제24권6호
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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.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2000년도 종합학술발표회 논문집 Vol.10 No.1
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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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 추계학술대회 논문집 학회본부 C
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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.

• 한국통신학회논문지
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• 제22권6호
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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.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.2365-2372
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• 2011

BLDC 모터와 같은 동기전동기에서 소음과 진동의 원인이 되는 코깅토크는 전동기내의 비 균일 토크로서 전동기 시스템의 자기 에너지가 최소인 위치로 이동하려는 접선방향의 힘으로 부하전류와 상관없이 회전자 영구자석과 고정자 슬롯의 상호작용에 의해 발생한다. 이러한 코깅토크는 전동기의 소음과 진동의 주요 원인이 되므로 전동기 설계 시 반드시 고려해야 한다. 코깅토크는 영구자석이 부착된 회전자에 의하여 공극 중에 비교적 저차의 고조파 자속밀도와 고정자 철심 슬롯의 상호작용으로 발생한다는 점을 중시하여 본 논문에서는 실험계획법의 일종인 반응표면 법을 사용하여 코깅토크를 저감하는 방법에 대해 제시하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제33권2호
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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.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 춘계학술대회논문집 - 한국공작기계학회
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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.