• 한국통신학회논문지
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• 제29권8A호
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• pp.962-971
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• 2004

본 논문에서는 모드매칭법을 이용하여 구형 도파관 내부에 금속의 Half cylinder에 의한 산란 특성을 해석하는 수치적 해석법을 제시하였고, Half cylinder의 반경 변화와 회전에 따른 산란 특성을 계산하였다. 또한, 제안된 방법이 일반산란계수법과 연계되었을 때 여러 개의 Half cylinder가 위치한 경우에도 적용 가능함을 보였다. 2 pole 필터의 계산 결과로부터 Half cylinder의 회전에 따라 공진 주파수의 조정이 가능함을 알 수 있었다. 계산 결과는 HFSS의 결과와 비교하여 잘 일치하였다. 본 논문에서 제시한 구조와 해석법은 튜닝 소자로 금속의 Half cylinder를 사용하는 도파관 관련 부품의 설계에 쉽게 이용될 수 있다.

• 대한기계학회논문집B
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• 제21권3호
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• pp.436-444
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• 1997

Three-dimensional conjugate heat transfer and particle deposition on a circular cylinder in the OVD process are numerically investigated. Flow and temperature fields are obtained by an iterative method, and thermophoretic particle deposition is simulated. Effects of the heat conduction in the cylinder, the rotation speed of the cylinder, and the traversing speed of torch on the deposition are studied. Effects of variable properties are also included. As the conductivity of the cylinder decreases, particle deposition rate and deposition efficiency greatly decrease due to the reduced temperature gradient. The rotation of the cylinder has no significant effect on the deposition due to the small diameter of the cylinder and low speed of rotation. Since the increase of the torch speed keeps the surface low temperature, the particle deposition increases with the traversing speed.

• 한국자동차공학회논문집
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• 제14권1호
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• pp.31-38
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• 2006

Cylinder liner rotation is a new concept for reducing piston assembly friction in the internal combustion engine. The purpose of cylinder liner rotation is to reduce the occurrence of boundary and mixed lubrication friction in the piston assembly. This paper reports the results of experiments to quantify the potential of the rotating liner engine. A GM Quad-4 SI engine was converted to single cylinder operation and modified for cylinder liner rotation. The hot motoring method was used to compare the friction loss between the baseline engine and the rotating liner engine. Additionally, tear-down tests were used to measure the contribution of each engine component to the total friction torque. The cycle-averaged motoring torque of the RLE represents a $23\~31\%$ friction reduction compared to the baseline engine for hot motoring tests. Through tear down tests, it was found that the piston assembly friction of the baseline engine is reduced from $90\%$ at 1200 rpm to $71\%$ at 2000 rpm through liner rotation.

• 한국해양공학회지
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• 제19권3호
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• pp.1-10
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• 2005

The effect of rotation on the unsteady laminar flaw past a circular cylinder is numerically investigated in the present study. The numerical solutions for the 2D Navier-Stokes equation obtained, using two different numerical methods. One is an accurate spectral method and the other is a finite volume method(FVM). First, the flaw around a stationary circular cylinder is investigated to understand the basic phenomenon of flaw separation and bluff body wake. Next, the flow characteristics of the laminar flow, past a rotating circular cylinder, are investigated, using a FVM developed in this study. By the effect of rotation, it is seen that values of lift increase, while the values of mean drag decrease. Further, the criteria of angular velocity, at which the Karman vorteces disappear, is also determined.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2004년도 학술대회지
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• pp.222-228
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• 2004

The effects of rotation on the unsteady laminar flow past a circular cylinder is numerically investigated in the present study. We obtained the numerical solutions for unsteady two-dimensional governing equation for the flow using two different numerical schemes. One is an accurate spectral method and another is finite volume method. Above all, the flow around a stationary circular cylinder is investigated to understand the basic phenomenon of flow separation, bluff body wake. Also, the validation of our own codes, expecially based on FVM, is carried out by the comparison of results obtained from our simulations using two different schemes and previous numerical and experimental studies. By the effect of rotation, the mean lift increases and drag deceases, which well represent the previous study.

• Interaction and multiscale mechanics
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• 제6권2호
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• pp.211-235
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• 2013

An incompressible smoothed particle hydrodynamics (ISPH) method based on the incremental pressure projection method is developed in this study. The Rayleigh-B$\acute{e}$nard convection in a square enclosure is used as a validation case and the results obtained by the proposed ISPH model are compared to the benchmark solutions. The comparison shows that the established ISPH method has a good performance in terms of accuracy. Subsequently, the proposed ISPH method is employed to simulate natural convection from a heated cylinder in a square enclosure. It shows that the predictions obtained by the ISPH method are in good agreements with the results obtained by previous studies using alternative numerical methods. A rotating and heated cylinder is also considered to study the effect of the rotation on the heat transfer process in the enclosure space. The numerical results show that for a square enclosure at, the addition of kinetic energy in the form of rotation does not enhance the heat transfer process. The method is also applied to simulate forced convection from a circular cylinder in an unbounded uniform flow. In terms of results, it turns out that the proposed ISPH model is capable to simulate heat transfer problems with the complex and moving boundaries.

• 대한기계학회논문집B
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• 제35권5호
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• pp.481-486
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• 2011

회전하는 실린더 주변의 액막 거동을 예측하는 것은 제철 산업에서 판재의 부식을 방지하기 위한 박막 코팅 과정에 매우 중요하게 적용될 수 있다. 판재 코팅에 사용할 박막을 만들기 위하여 실린더를 회전하는 경우, 실린더 주변 액막의 거동은 실린더 지름 및 회전 속도, 중력, 유체의 물성에 따라 영향을 받는다. 이러한 변수의 영향으로 실린더를 따라 상승하는 액막의 거동 특성 및 실린더 주변 액막 두께가 결정된다. 본 연구에서는 회전하는 실린더 주변 액막 거동에 대한 경계면을 갖는 이상유동에 대해 VOF 방법을 사용하여 수치해석하였다. 다양한 회전 속도, 실린더 지름, 유체 점성, 표면장력에 따른 액막 거동의 이상유동에 대한 수치해석을 통해 액막 두께를 예측할 수 있었다. 이를 통해, 회전 속도, 실린더 지름 및 유체 점성이 증가함에 따라 더 많은 액막을 상승시켜 두꺼운 액막을 형성하였으며, 이러한 액막 두께에 대한 수치해석 결과는 기존 실험 및 이론적 상관식과 일치하는 결과를 보였다.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2001년도 제34회 추계학술대회 개최
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• pp.151-158
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• 2001

This paper presents a method for evaluating the lubrication characteristics between the plunger and cylinder in a radial type plunger pump. A numerical analysis is carried out in order to obtain the pressure distribution and acting forces between the plunger and cylinder. The pressure distribution is also measured experimentally by using pressure transducer through the cam type test machine. The experimental pressure distribution result is compared with the numerical result which is estimated by the computer simulation. In conclusion, the acting forces to the plunger are expressed for the operating conditions such as clearance, supply pressure, rotation speed and viscosity of oil.

• 대한기계학회논문집
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• 제18권1호
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• pp.193-202
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• 1994

A study of heat transfer and particle deposition has been made numerically for outside vapor deposition process. Heat conduction through the two layer cylinder which consists of the target and the deposited layer is included together with heat transfer and gas jet flow onto the cylinder from the torch. Temperature and flow fields have been obtained by an iterative method and thermophoretic particle deposition has been studied. Of particlar interests are effects of the thickness of the deposited layer, the torch speed and the rotation speed of the cylinder on particle deposition flux and efficiency. Effects of buoyancy, variable properties and tube rotation are included.

• Journal of applied mathematics & informatics
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• 제22권1_2호
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• pp.67-82
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• 2006

In this paper, we present a finite difference method for the implementation of the rotation of a circular cylinder in the incompressible flow field by solving the two-dimensional unsteady Navier-Stokes equations. The approach is to use staggered grid method so that the accuracy and order of convergence of the associated algorithms can be maintained. The proposed method is easy to be implemented and is effective. A set of simulations for the flow dynamics is provided to show the computational results.