• International Journal of Air-Conditioning and Refrigeration
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• v.15 no.1
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• pp.1-9
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• 2007

This study concerns the characteristics of helical flow in a concentric and eccentric annulus with a diameter ratio of 0.52 and 0.9, whose outer cylinders are stationary and inner ones are rotating. Pressure losses and skin friction coefficients have been measured for fully developed flows of water and 0.2% aqueous of sodium carboxymethyl cellulose (CMC), respectively, when the inner cylinder rotates at the speed of 0-500 rpm. The effect of rotation on the skin friction is significantly dependent on the flow regime. In all flow regimes, the skin friction coefficient is increased by the inner cylinder rotation. The change of skin friction coefficient corresponding to the variation of rotating speed is large for the laminar flow regime, whereas it becomes smaller as Re increases for the transitional flow regime and, then, it gradually approach to zero for the turbulent flow regime.

• The Korean Journal of Cytopathology
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• v.7 no.2
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• pp.185-191
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• 1996

Metastatic melanoma is often difficult to diagnose morphologically. However, the prognostic and therapeutic decision in cases of metastatic melanoma depends upon the morphologic documentation of the metastatic disease, which may rapidly and accurately be done by cytologic methods such as aspiration cytology of clinically suspicious lesion. Cytological features of 12 metastatic melanoma are described. Evaluation for melanin pigment, background composition, cytoplasmic vacuoles, intranuclear inclusions, bi- or multinucleated cells, eccentric nuclei, nucleoli, and degree of cellular cohesion were made. the presence of melanin pigment, prominent nucleoli, intranuclear cytoplasmic inclusions, lack of cell cohesion, and eccentric nuclei are the important and useful cytologic features in the diagnosis of metastatic melanoma. Bi or multinucleated cells, cytoplasmic vacuoles, and bloody background are also frequently found in smears from metastatic melanoma.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.2
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• pp.60.1-60.1
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• 2013

We study tidal disruption and subsequent mass fallback process for stars approaching supermassive black holes on bound orbits, by performing three dimensional Smoothed Particle Hydrodynamics simulations with a pseudo-Newtonian potential. We find that the mass fallback rate decays with the expected -5/3 power of time for parabolic orbits, albeit with a slight deviation due to the self-gravity of the stellar debris. For eccentric orbits, however, there is a critical value of the orbital eccentricity, significantly below which all of the stellar debris is bound to the supermassive black hole. All the mass therefore falls back to the supermassive black hole in a much shorter time than in the standard, parabolic case. The resultant mass fallback rate considerably exceeds the Eddington accretion rate and substantially differs from the -5/3 power of time. We also show that general relativistic precession is crucial for accretion disk formation via circularization of stellar debris from stars on moderately eccentric orbits.

• Journal of KSNVE
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• v.10 no.3
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• pp.401-409
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• 2000

Vibration of a BLDC motor is a coupled phenomenon between mechanical characteristics and magnetic origins through the motor air-gap. When a relative misalignment of rotor in the air-gap center exists on the assemblage it is considered to influence the motor system characteristics, depending on the degree of misalignment. The rotor-motor system used in a washing machine is modeled using FE-TM and a magnetic force of BLDC motor with radial rotor eccentricity is analyzed. And the transient whirl responses of a rotor system with relative misalignment in the motor air-gap are investigated considering mechanical origins and magnetic effects. Results show that rotor misalignment in the air-gap affect the vibration of the rotor-motor system.

• Journal of KSNVE
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• v.10 no.3
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• pp.536-550
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• 2000

Inversitgated in this study are the modal characteristics of the eccentric cylindrical shells with fluid-filled annulus. Theoretical method is developed to find the natural frequencies of the shell using the finite Fourier expansion and their results are compared with those of finite element method to verify the validation of the method developed. The effect of eccentricity on the modal characteristics of the shells is investigated using a finite element modeling.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1660-1663
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• 2005

Unwanted vibrations are inevitably induced in other directions when pure unidirectional vibration motion is desired for the vertical scratching mechanism. Pure vertical vibration motion of the scratching machine can be obtained by driving identical two motors with symmetrically positioned eccentric unbalance masses. The desired optimal condition for driving pure vertical vibration for the scratching machine is assumed to be the resonance condition in that direction. Imposing the flexibility of the scratching machine in the horizontal direction, we can find out the amount of horizontal vibration component while maintaining the resonance in vertical direction. The desired stiffness in horizontal direction which produces the minimum vibration in horizontal direction are defined which can be used as a guide line to design the supporting structure of the scratching machine.

• The Korean Journal of Applied Statistics
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• v.23 no.4
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• pp.777-781
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• 2010

Yates' continuity correction of the chi-squared test for testing the homogeneity of two binomial proportions in $2{\times}2$ contingency tables is developed to lower the value of the test statistic slightly. The effect of continuity correction is expected to decrease as the sample size increases. However, in extremely unbalanced $2{\times}2$ contingency tables, we find some cases where the effect of continuity correction is eccentric and is larger than expected. In such cases, we conclude that the chi-squared test with continuity correction should not be employed as a test statistic in both asymptotic tests and exact tests.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.12
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• pp.140-145
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• 2004

In this study, the design and analysis of a butterfly valve disk was performed to minimize the rubbing between the disk and the seat at opening and closing. The butterfly valve has double eccentric structure and the contact surface between the disk and the seat is a conical surface. At the instant of opening and closing the valve by the rotation of disk, the positions of zero contact point are changed. Also, if the cone surface is cut in the perpendicular direction to the rotation axis of the valve, the contour of cutting section is hyperbolic. Therefore minimum distance between the origin of the eccentric axis and the hyperbolic curve goes to the position of zero contact point. In order to consider the interferences between the disk and the seat, the thermal-structure coupled field analysis was performed by ANSYS.

• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.179-182
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• 2004

혈관의 협착으로 인만 혈류의 교란과 그로 인한 초음파 반향의 영향을 튜브에 편심 협착 (eccentric stenosis)을 부착하고 돼지 혈액을 이용해 실험실에서 연구했다. 상용화된 GE LOGIQ 700 Expert 시스템과 M12L 의 선형 트랜스듀서를 이용해 B-모드 영상을 얻은 후 편심 협착 상류 지점과 하류 지점의 초음파 영상을 비교하여 분석하였다. 분당 20 회와 40 회의 박동율과 혈류속도를 바꿔가며 혈류의 교란에 따른 혈액에서의 초음파 영상을 분석한 결과, 편심 협착으로 인한 혈류의 교란으로 적혈구 응집현상이 달라져 복잡한 초음파 반향 분포가 형성되었다. 비침습적 실시간 초음파 영상은 편심 협착으로 인한 혈류의 교란과 그로 인한 혈액의 적혈구 응집 현상을 이해하고 연구하는데 도움이 된다.

• 한국가시화정보학회:학술대회논문집
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• 2005.12a
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• pp.69-73
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• 2005

Three-dimensional density distributions of an impinging and eccentric flame have been analyzed numerically and experimentally by a combined optical system with a digital speckle tomography. The flame has been ignited by premixed butane/air from air holes and impinged vertically against a plate located at the upper side of tile burner nozzle. In order to compare with experimental data, computer synthesized phantoms of impinging and eccentric flames have been made and reconstructed by a developed three-dimensional multiplicative algebraic reconstruction technique (MART). A new scanning technique has been developed for the analysis of speckle displacements to investigate wall jet regions of the impinging flame including sharp variation of the flow direction and pressure gradient. The reconstructed temperatures have been compared with a temperature photography by an infrared camera and results of numerical analysis using a finite-element method.