• 한국소음진동공학회논문집
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• 제23권4호
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• pp.338-346
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• 2013

Equations of motion of a rotating blade considering pre-twist angle, cross section taper and a concentrated mass are derived using the hybrid deformation variable modeling method. For the modeling of a concentrated mass which is located at an arbitrary position of the blade, a Dirac delta function is employed for the mass density function. The final equations for the vibration analysis are transformed into a dimensionless form using several dimensionless parameters. The effects of the dimensionless parameters on the vibration characteristics of the rotating blade are investigated through numerical analysis.

• 한국정밀공학회지
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• 제24권12호
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• pp.42-49
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• 2007

When micro holes are machined by EDM, machining characteristics of machined holes are changed according to the machining conditions. Typical machining conditions are the kind of dielectric fluids, capacitance and ultrasonic vibrations. They influence electrode wear, machining time, radial clearance and taper angle. In this paper, machined holes whose depths are 300, 500, $1000\;{\mu}m$ are observed for each machining conditions. Using deionized water as a dielectric fluid makes electrode wear small, machining time short, radial clearance large and taper angle small. High capacitance makes electrode wear high. Ultrasonic vibrations make electrode wear large, machining time short, radial clearance small and taper angle small. From the results of experiments, the optimal machining conditions were obtained to machine highly qualified micro holes.

• Structural Engineering and Mechanics
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• 제63권1호
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• pp.103-113
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• 2017

Free vibration analysis of plates is necessary for the field of structural engineering because of its wide applications in practical life. Free vibration of plates is largely dependent on its thickness, aspect ratios, and boundary conditions. Here we investigate the natural frequencies of simply supported tapered isotropic rectangular plates with internal cutouts using a nine node isoparametric element. The effect of rotary inertia on Eigenfrequencies was demonstrated by calculating with- and without rotary inertia. We found that rotary inertia has a significant effect on thick plates, while rotary inertia term can be ignored in thin plates. Based on comparison with literature data, we propose that the present formulation is capable of yielding highly accurate results. Internal cutouts at various positions in tapered rectangular simply supported plates were also studied. Novel data are also reported for skew taper plates.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2002년도 하계학술대회 및 세미나
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• pp.21-23
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• 2002

In millimeter wave applications, it is often necessary to use transitions between waveguide and planar circuits. Finline structures can be used effectively to this purpose. In multilayered case, it is necessary to analyze the structure with numerical method such as spectral domain immittance method. The design procedure uses tile cutoff frequency for each taper width. The dispersion data in a single layer are compared with those in literature. The performance of the designed finline taper is verified with the FEM simulation using HFSS.

• 한국전기전자재료학회논문지
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• 제13권12호
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• pp.1051-1057
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• 2000

A traveling-wave CPW(coplanar waveguide) electrode with abruptly broken input/output-taper for LiNbO$_3$optical modulator was designed and fabricated. The electrical characteristics of traveling-wave electrode on z-cut LiNbO$_3$crystal with SiO$_2$buffer layers were measured by network analyzer. To confirm the possibility of the electro-optic modulator electrode, detailed calculations of the impedance, microwave effective index and attenuation constants are presented as a function of the microwave electrode thickness, but the buffer layer thickness is fixed as 1${\mu}{\textrm}{m}$. These characteristics are discussed from the viewpoint of the device optimization and are expected to be design guides for the LiNbO$_3$modulator’s electrodes.

• 대한기계학회논문집
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• 제17권2호
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• pp.257-266
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• 1993

본 연구에서는 보강롤의 굽힘변형을 고려한 젠지미어 압연기의 롤변형 해석을 통해, 궈터웨이브의 발생을 시뮬레이션하고, 형상제어 수단들의 궈터웨이브 억제에 미 치는 영향을 분석하여 궈터웨이브 감소 방안을 수립하였고, 실제 현장 압연실험을 통 해 그 제어효과를 확인하였다.

• 산업경영시스템학회지
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• 제23권59호
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• pp.119-127
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• 2000

This paper describes the database for wire cutting electrodischarge conditions and variable taper wire-cut Machining. Electodischarge wire-cut machining is applicable to all materials that are fairly good electrical conductors, including metals, alloys, and most carbides. Thus it provides a relatively simple method for making holes of any desired cross section in materials that are too hard or brittle to be machined by most other methods. In conventional wire cutting CAM systems usually generate the NC code omitting electrodischarge conditions, so operator edits the NC code manually. But it is very inefficient. Therefore in this paper we propose a wire cutting CAM system including database for electrodischarge conditions. Proposed system consists of three steps: 1) Development of database for electrodischarge conditions 2) Development of CAM functions, Including 2D CAD modeling tools, file I/O functions, wire path genera tion functions and postprocessor. 3) Development of variable taper wire-cut machining module. The proposed system has been tested in the JinYoung precision Machine Co.,LTD. and found to be working satisfactorily.

• 한국광학회지
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• 제7권1호
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• pp.77-86
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• 1996

$Ti:LiNbO_3$ Mach-Zehnder 진행파형 광변조기의 CPW(coplanar waveguide) 전극구조, 특히 taper영역을 해석하기 위해서 SOR(successive over relaxation)법을 이용하였다. 변조기의 taper영역에서는 임피던스 정합, 즉 $Z_c 가 50\omega$이 만족되는 전극구조를 설계하였다. 변조기의 변조영역에서는 $Z_c=50\omega, n$$Z_c$ c/=50.OMEGA., n=2.26인 설계파라미터와, n$_{eff}$=2.2, Z$_{c}$=47.7.OMEGA.인 설계파라미터를 찾았다.

• Journal of the Optical Society of Korea
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• 제11권1호
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• pp.40-43
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• 2007

We propose a taper-underlaid spot-size converter (TU-SSC) with an offset which consists of two vertically stacked taper layers. The designed TU-SSC reduces coupling loss of a high index-contrast waveguide with $1.5%{\Delta}$ to a single mode fiber from 1.5 dB to 0.27 dB. We also considered the effects of mask misalignment in the fabrication process of TU-SSC, and optimized the design of TU-SSC so that the additional loss of TU-SSC for the mask misalignment of $3{\mu}m$ in the photo-lithography process was as low as 0.13 dB.

• 소음진동
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• 제9권3호
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• pp.607-612
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• 1999

일반적으로 보아 고유진동수는 주어진 보의 진동해석 및 동적 안정해석에서 대단히 중요한 역할을 한다. 그러나 보의 단면이 부재축에 따라 연속적으로 변할 때의 고유진동수 산정은 해석적 방법으로는 불가능하거나 대단히 복잡한 것이 보통이기 때문에 수치해석법을 이용하게 된다. 여기서는 유한요소법에 의하여 고유진동수를 산정하였으며 수치해석법의 결과를 일반화하기 위하여 taper ratio를 변수로 하는 회귀식을 제안하였다. 회귀식을 이용한 고유진동수의 추정치는 해석적 방법으로 얻어진 값 또는 수치해석 결과로부터 얻어진 값들과 비교적 잘 일치한다.