• 대한기관식도과학회지
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• 제16권2호
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• pp.131-137
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• 2010

Background: Montgomery T-tube is widely used to maintain airway in many cases. Market-available tubes are not always fit to the trachea of each patient and need some modification such as trimming. Complications do happen in prolonged use like tracheostomy tubes. To overcome above limitations, we designed custom-made T-tube using CT data with the aid of 3D reconstruction software. Material and Method: Boundaries were extracted from neck CT data of normal person and processed by surface rendering methods. Real laryngotracheal model and tracheal inner surface-mimicking tube model were made with plaster and rubber. The main tube was designed by accumulation of circles or simple closed curves made from boundaries. Stomal tube was made by accumulation of squares due to limitation of software. Measurement data of tracheal lumen were used to custom-made T-tubes. Tracheal lumen residing portion (vertical limb) was made like circular cylinder or simple closed curved cylinder. Stomal portion (horizontal limb) was designed like square cylinder. Results: Custom made T-tube with cylindric vertical limb and horizontal limb of square cylinder was designed. Conclusion: CT data was helpful in making custom made T-tube with 3D reconstruction technique. If suitable materials are available, commercial T-tube can be printed out from 3D printers.

• Journal of Mechanical Science and Technology
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• 제19권12호
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• pp.2270-2280
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• 2005

An experimental study is performed for turbulent swirling flow behind a circular cylinder using 2-D PIV technique. The Reynolds number investigated are 10,000, 15,000, 20,000 and 25,000. The mean velocity vector, time mean axial velocity, turbulence intensity, kinetic energy and Reynolds shear stress behind the cylinder are measured before and behind the round cylinder along the test tube. A comparison is included with non swirl flow behind a circular and square cylinder. The recirculation zones are showed asymmetric profiles.

• 대한기계학회논문집B
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• 제24권11호
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• pp.1478-1485
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• 2000

An experimental study has been performed to investigated the forced convection heat transfer characteristics of 6 circular cylinders in staggered arrangement in a cross flow of air. The water scale deposited on condenser wall of power plant was used to investigate the effect of roughness of scaled surfaces. The relative roughness*average diameter of scale/cylinder diameter) was in a range of k/d=0.0066, 0.0111, 0.0167, 0.0222 and 0.0278. The cylinder spacings(L/d) varies from 1.5 to 4.0 where L denote the cylinder spacings along and normal to the upstream uniform flow direction. The Reynolds number was varied in a range of 10, 000$\leq$ Re $\leq$ 50,000. The local and mean Nusselt numbers were investigated as a function of scale roughness, the cylinder spacing and Reynolds number. The results are compared with those of clean cylinder and inline tube bank, subsequently the mean fouling resistance over the entire circumference was estimated from those results as a function of scale roughness, the cylinder spacing and Reynolds number.

• 산업기술연구
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• 제8권
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• pp.71-80
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• 1988

높은 전압으로 충전된 Capacitor를 순간적으로 원통형 coil에 방전하면 순간적으로 강한 전자장 impulse가 발생한다. 이때 coil를 둘러 싼 금속 tube는 radial 방향의 힘을 얻어 팽창한다. 본 논문은 이때 tube내의 전자장분포와 tube 벽의 움직임을 integral equation method를 사용하여 해석하였다.

• 설비공학논문집
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• 제19권11호
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• pp.743-750
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• 2007

In this study, ice slurry generator using air cylinder was designed and manufactured to investigate the heat transfer characteristic of the ice slurry generator. The ice slurry generator has the same shape as the shell-and-tube type heat exchanger. Refrigerant is flowing in the shell side and ethylene glycol solution in the tube side. The experiment was conducted on performance of ice slurry generator using air cylinder with standard condition and the results are plotted on the time scale. The experimental tests on the various concentration of ethylene glycol solution, the various solution velocity in the tube side and the various tube size have been carried. For the above experimental conditions, ice making characteristics of the ice slurry generator are evaluated in terms of the overall heat transfer coefficient. And the experimental results show that the overall heat transfer coefficient of the system is increased as the tube size and the concentration of ethylene glycol decreases.

• Journal of Electrochemical Science and Technology
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• 제15권1호
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• pp.190-197
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• 2024

A commercial PbO₂ mesh cylinder electrode was utilized as the anode for the electrochemical degradation of the textile effluent after the biological treatment with the titanium cylinder as the cathode in a self-made tube electrolyzer. The electrochemical performances of the PbO₂ electrode in tube electrolyzer under different initial pH, electrolyte flow rates, current densities and times of the electrochemical degradation were investigated. The experimental results illustrated that the PbO₂ electrode can reduce the chemical oxygen demand (COD) of the textile effluent from 94.0 mg L^-1 to 65.0 mg L^-1 with the current efficiency of 88.3%, the energy consumption of 27.7 kWh kg^-1 (per kilogram of degraded COD) and the carbon emissions of 18.0 kg CO₂ kg^-1 (per kilogram of degraded COD) under the optimal operating conditions. In addition, the COD of the textile effluent could be reduced from 94.0 mg L^-1 to 22.0 mg L^-1 after the fifth electrochemical degradation. Therefore, PbO₂ mesh cylinder electrode in the tube cylinder was promising for the electrochemical degradation of the textile effluent.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2004년도 추계학술대회 논문집
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• pp.5-9
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• 2004

An experimental study is performed turbulent swirling flow behind a crcular cylinder using 2-D PIV technique. The Reynolds number investigated is 15,000. The mean velocity vector, time mean axial velocity, turbulence intensity, kinetic energy and Reynolds shear stress behind the cylinder are measured before and behind the cylinder along the test tube.

• 대한기계학회논문집B
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• 제28권2호
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• pp.174-180
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• 2004

Failure of tube bundles due to excessive flow-induced vibrations continues to affect the performance of nuclear power plant Early experimental studies concentrated on rigid structures and later investigators dealt with elastic structures because of their importance in many engineering fields. On the other hand, much less numerical work has been carried out, because of the numerical complexity associated with the problem. Conventional approaches usually decoupled the flow solution from the structural problem. The present numerical study proposes the methodology in analyzing the fluidelastic instability occurring in tube bundles by coupling the Computational fluid Dynamics (C%) with the tube equation of motions. The motion of the structures is modeled by a spring-damper-mass system that allows transnational motion in two directions (a two-degree-of-freedom system). The fluid motion and the cylinder response are solved in an iterative way, so that the interaction between the fluid and the structure can be accounted for property. The aim of the present work is to predict the fluidelstic instability of tube bundles and the associated phenomena, such as the response of the cylinder, the unsteady lift and drag on the cylinder, the vortex shedding frequency.

• 한국가스학회지
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• 제22권2호
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• pp.72-77
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• 2018

본 연구에서는 볼밸브와 긴 실린더 튜브로 구성된 LPG 충전장치의 강도안전성에 대한 FEM 해석결과를 제시하고 있다. LPG 충전장치의 강도안전성 해석을 위해 1.7~3.5mm의 벽면 두께를 갖는 볼밸브와 긴 실린더 튜브에 0.5~3.5MPa의 가스압력을 공급하였다. 1.7mm 벽면 두께를 갖는 볼밸브에 3.5MPa의 가스압력을 공급하였을 때 발생한 von Mises 최대응력은 25.4MPa이고, 이 값은 황동소재 항복강도의 25.9%에 해당한다. 그리고 1.7mm 벽면 두께를 갖는 긴 실린더 튜브에 3.5MPa의 가스압력을 공급하였을 때 발생한 von Mises 최대응력은 23.7MPa이고, 이 값은 동일한 조건으로 해석한 볼밸브에 비해 6.7%나 더 안전한 것으로 나타났다. 긴 실린더 튜브의 벽면 두께를 2.0mm로 증가시켰을 경우 발생한 von Mises 최대응력 20.2MPa은 1.7mm의 벽면 두께를 갖는 같은 실린더 튜브에 비해 14.8%나 더 안전하였다. 따라서 본 연구에서는 볼밸브와 실린더 튜브의 강도안전성을 확보하기 위해서는 벽면의 두께를 1.7~2.0mm 정도로 최적화된 LPG 충전장치가 바람직하다.

• 태양에너지
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• 제7권2호
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• pp.86-97
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• 1987

Natural convection in the annulus between a horizontal conducting tube and a cylinder with spacers has been studied by 2-dimensional numerical method with finite difference techniques. The effects of Rayleigh number, conductivities of conducting tube and spacer, and position of spacers were studied analytically. In case of vertical spacers, the maximum local Nusselt number appears at ${\theta}{\approx}50^{\circ}$ in a conducting tube and ${\theta}{\approx}30^{\circ}$ in an outer cylinder, The local Nusselt numbers show positive values on the lower spacer, but negative values on the surface of the upper spacer. In case of horizontal spacers, the flow over the spacer is more active than that of under the spacer as the Rayleigh number increases. The maximum local Nusselt appeares at ${\theta}=180^{\circ}$ in a conducting tube and at ${\theta}=0^{\circ}$ in an outer cylinder. The local Nusselt numbers show positive values on the upward surface, but negative values on the downward surface of spacer. As the dimensionless conductivity increases, the mean Nusselt number remarkably increases at $K_w/K_f<48$ and show almost even at $K_w/K_f{\ge}48$. The mean Nusselt number of a conducting tube with vertical spacers is 5.12 percent less and with horizontal spacers is 11.33 percent less than that of a conducting tube without spacer at $Ra=10^4$, Pr = 0.7 and $K_w/K_f=48$.