• 한국조명전기설비학회지:조명전기설비
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• 제5권2호
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• pp.37-48
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• 1991

본 연구에서는 Reynold수가 $0-10.52{\times}10^4$의 범위에서 유동공기중의 전로파괴의 특성을 연구하였다. 또한 일정한 입력전력에서 Reynold수의 조정에 의한 방전 Pattern의 변화를 연구하였다. 그리고 실험에 사용된 유로는 원통관이다. 측정부에서의 흐름은 완전히 발달한 층류로 이루어졌다. 본 연구에서 얻은 중요한 결과는 다음과 같다. 유동공기중의 전로파괴는 공기의 흐름장 이론에 의해 분석이 가능하며 전로파괴전압은 Reynold수가 $3{\times}10^2$-$4{\times}10^4$의 범위에서 거의 최대값을 나타낸다. 유동 공기중의 최대전로파괴전압은 정지시보다 평굼 6.3[kV]높게 나타났다. 방전 pattern은 Reynold수의 조정에 의하여 제어할 수 있었다.

• 한국광학회지
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• 제5권4호
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• pp.461-465
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• 1994

레이놀드 수에 따른 색소 젯트의 공간적인 편평도를 마이켈슨 간섭계를 이용하여 분석하였다. 레이놀드 수 600(유속 12m/s)일 때 색소 젯트의 편평도는 최적 조건을 보였다. 이러한 색소 젯트의 최적 조건하에서 종펌핑 Littman형 색소레이저 빔은 펌프 에너지 0.5-1.0mJ/pulse의 범위에서 단일 종모우드로 발진되었다. 이 때의 선폭은 470MHz이었고, 변환 효율과 빔 발산각은 각각 4.7%, 3mrad이었다.

• Steel and Composite Structures
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• 제42권3호
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• pp.389-396
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• 2022

This investigation in fluid mechanics surrounds around the variety of flow problems for different fluids along the stretching cylinder. Numerical procedure is carried out for the obtained resultant equations by Keller-Box technique. Numerical study of laminar, steady, viscous and incompressible two dimensional boundary layer flow of effects of suction and blowing on boundary layer slip flow of Casson fluid along permeable exponentially stretching cylinder has been carried out in the present draft. physical parameters i.e., Nusselt number and skin friction coefficient, suction parameter and the local Reynold number are investigated on velocity profile and elaborated through proper graphs and table.

• 대한조선학회논문집
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• 제46권6호
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• pp.569-577
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• 2009

As the scale factor of model propellers utilized in cavitation test is about 40, it is difficult to find out practical countermeasures against the small area erosions on the blade tip region throughout model erosion tests. In this study, a partial propeller blade model was used for the observation of cavitation pattern for the eroded propeller. A partial propeller blade model was manufactured from 0.7R to tip with expanded profile and with adjustable device of angle of attack. Reynold's number of a partial propeller blade model is 7 times larger than that of a model propeller. Also, anti-singing edge and application of countermeasures to partial propeller blade model which produced in large scale can be more practical than a model propeller. For the observation of cavitation at high Reynold's number, high speed cavitation tunnel was used. To find out the most severe erosive blade position during a revolution, cavitation observation tests were carried out at 5 blade angle positions.

• Advances in nano research
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• 제10권3호
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• pp.263-270
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• 2021

The present manuscript focuses the effects of suction on the flow of the dusty fluid along permeable exponentially stretching cylinder. Derived PDEs for this work are changed into ODEs by adopting right transformations. Numerical procedure is carried out for the obtained resultant equations by Shooting Technique in accordance with Runge-Kutta (RK-6) technique. Obtained results for the parameters namely, particle interaction parameter, suction parameter and Reynold number parameters are probed thoroughly. Some salient points are: (a) Fluid velocity decreases and the dust phase velocity rises for the higher values of particle interaction parameter; (b) more suction produces retarding velocities for both the phases; (c) high Reynold number slows down the fluid velocity while the speed of dust phase and (d) skin friction coefficient goes high for all these parameters.

• Journal of Biosystems Engineering
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• 제33권1호
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• pp.1-6
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• 2008

The output of the Stirling engine is influenced by the regenerator effectiveness. The regenerator effectiveness is influenced by heat transfer and flow friction loss of the regenerator matrix. In this paper, in order to provide basic data for the design of regenerator matrix, characteristics of flow friction loss were investigated by a packed method of matrix in the oscillating flow as the same condition of operation in a Stirling engine. As matrices, two different wire screens were used. The results are summarized as follows; 1. With the wire screen of No. 50 as regenerator matrices, pressure drop of working fluid of the oscillating flow is shown as 3 times higher than that of one directional flow, not too much influenced by the number of packed meshes. 2. With the wire screen of No. 100 as regenerator matrices, pressure drop of working fluid of the oscillating flow is shown as 2.5 times on the average higher than that of one directional flow, not too much influenced by the number of packed meshes. 3. Under one directional flow which used regenerator matrices with both 200, 240, and 280 wire screens of No. 50 and 320, 370, and 420 wire screens of No. 100, the relationship between the friction factor and Reynold No. is shown as the following formula. $$f=\frac{0.00326639}{Re\iota}-1.29106{\times}10^{-4}$$ 4. Under oscillating flow which used regenerator matrices with both 200, 240, and 280 wire screens of No. 50 and 320, 370, and 420 wire screens of No. 100, the relationship between the friction factor and Reynold No. is shown as the following formula. $$f_r=\frac{0.000918567}{Re\iota}+1.86101{\times}10^{-5}$$ 5. The pressure drop is shown as high in proportion as the number of meshes has been higher, and the number of packed wire screens as matrices increases.

• 대한토목학회논문집
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• 제14권3호
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• pp.669-678
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• 1994

침지여상에 폐수를 부하하여 간접포기 강제순환 방식으로 처리하는 system에 대하여 그 유기물 제거 특성을 실험적으로 연구했다. 실험은 침지여상에 네트링(random형(型) plastic media), 입체철망(module형(型) plastic media) 및 잔자갈의 특성이 다른 세가지 media를 충전하고, pH, 수온(水溫)을 고정한 상태에서 $BOD_5$ 용적부하와 순화비를 변동하여 실시하므로서 여재(media) 종류가 $BOD_5$ 제거효율에 미치는 특성을 규명했다.

• Journal of applied mathematics & informatics
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• 제12권1_2호
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• pp.267-279
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• 2003

The present investigation deals with the application of Adomian's decomposition method to blood flow through a constricted artery in the presence of an external transverse magnetic field which is applied uniformly. The blood flowing through the tube is assumed to be Newtonian in character. The expressions for the two-term approximation to the solution of stream function, axial velocity component and wall shear stress are obtained in this analysis. The numerical solutions of the wall shear stress for different values of Reynold number and Hartmann number are shown graphically. The solution of this theoretical result for a particular Hart-mann number is compared with the integral method solution of Morgan and Young［17］.

• Advances in nano research
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• 제10권4호
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• pp.349-357
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• 2021

In present study, the numerical investigations are carried out for effects of suction and blowing on boundary layer slip flow of casson nano fluid along permeable stretching cylinder in an exponential manner. The modeled PDEs are changed into nonlinear ODEs through appropriate nonlinear transformations. Change in physical quantities like friction coefficient, Nusselt and Sherwood numbers with variation of the aforementioned parameters are also examined and their numerical values are listed in the form of tables. Effects of Reynold number, suction parameter, Prandtl number, Lewis number, Brownian motion parameter and thermophoresis parameter are seen graphically with temperature profile.

• 동력기계공학회지
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• 제10권3호
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• pp.17-22
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• 2006

Surface modifications like rib-roughening and displaced insert devices like the twisted tape are commonly used in applications such as compact heat exchangers and cooling systems. In this paper, regionally averaged heat transfer distributions in square channels with twisted tape inserts and with twisted tape inserts plus interrupted ribs are respectively investigated. The square ribs are arranged to follow the trace of the twisted tape and along the flow direction defined as axial interrupted ribs. Each wall of the square channel is composed of isolated aluminum sections. Regionally averaged Nusselt number and channel averaged Nusselt number in turbulent air flows are presented for Reynold numbers from 8,900 to 29,000. We have obtained the following conclusions from the experimental study: 1) The local Nusselt number in the two-sided heated case is higher than that in the four-sided heated condition. 2) In the 4 heating wall channel with twisted tape inserts, Nusselt number based on bottom wall temperature is enhanced by 1.2 - 1.6 times if adding the axial interrupted ribs on the bottom wall only. 3) The twisted tape with interrupted ribs under the two-sided heating condition produces the highest heat transfer coefficient.