• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.13 no.4
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• pp.209-214
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• 1984

Friction factors and equivalent sand roughness of PVC pipe fittings have been studied by experiments in the Reynolds number range of $2,000\~70,000$. PVC pipe fittings studied are straight pipes, $90^{\circ}$ elbows and tees with 15, 25, and 40mm in norminal diameter, all manufactured in Korea with KS mark approval. Equivalent relative roughness of PVC pipes obtained lies between smooth pipe and 0.002. The study shows that equivalent sand roughness of PVC pipes increasses in proportion of the square root of pipe diameter , and can be approximately abtained by multiplying 4 to the root mean square value measured by metal surface roughness tester. Loss coefficient of PVC $90^{\circ}$ elbows decreases slowly with increasing Reynolds number. Loss coeffiicent of tees is a function of ratio of flow rates and Reynolds number.

• 한국전산유체공학회:학술대회논문집
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• 2008.08a
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• pp.49.5-50
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• 2008

• Journal of Mechanical Science and Technology
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• v.15 no.11
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• pp.1533-1540
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• 2001

A high-temperature sodium stainless steel heat pipe was fabricated and its performance has been investigated. The working fluid was sodium and it was sealed inside a straight tube container made of stainless steel. The amount of sodium occupied approximately 20% of the total volume of the heat pipe and its weight was 65.7gram. The length of a stainless steel container is 1002mm and its outside diameter is 25.4mm. Performance tests were carried out in a room air condition under a free convective environment and the measured temperatures are presented. The start-up behavior of the heat pipe from a frozen state was investigated for various heat input values between 600W and 1205W. In steady state, axial temperature distributions of a heat pipe were measured and its heat transfer rates were estimated in the range of vapor temperature from 50$0^{\circ}C$ to 63$0^{\circ}C$. It is found that there are small temperature differences in the vapor core along the axial direction of a sodium heat pipe for the high operating temperatures. But for the range of low operating temperatures there are large temperature drops along the vapor core region of a sodium heat pipe, because a small vapor pressure drop makes a large temperature drop. The transition temperature was reached more rapidly in the cases of high heat input rate for the sodium heat pipe.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.9
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• pp.1866-1873
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• 2002

The pipe-cutting machine developed in this study is a portable device used to cut a steel pipe. The machine, which is attached to the steel pipe by magnetic force, is moving around the pip e using four wheels. It also works for straight cutting of a steel plate. For the higher precision and labor time reduction, the automation of a pipe-cutting process is needed. However, it is not easily achieved because of vibrations and the loss of track. It is also found that the problems of the automation arise from the coupling of the functional requirements for the pipe-cutting machine. So, it is very difficult io solve the problems by a conventional design method. To overcome the difficulties the new design process for the pipe-cutting machine is established by axiomatic approach in this paper. Based on the Independence Axiom design process, a new product is designed and manufactured. Finally, it is verified by experiments that the performance of the automatic pipe-cutting machine is improved

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.436-439
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• 2008

This paper is to research the heat transfer performance of the sintered pipe. Recently, oil prices is to be 127 $ per barrel, we expect higher costs this summer. We promote alternative fuels, after oil and gasoline prices reached record highs. The governments have made efforts to avoid future crisis by continuing the move toward renewable energy and energy saving. In this paper, we have fabricated a sintered pipe, the heat transfer performance of sintered pipe is achieved experimentally. The pipe is copper tube of outer diameter of 15.88 mm, the length of the pipe is 800 mm. Based on the experimental results, it is shown the overall heat transfer coefficient of sintered pipe is increased as compared with that of a straight pipe, is equal as compared with that of a spiral pipe. The overall heat transfer coefficient was $0.075{\sim}0.09\;kW/^{\circ}C$

• Journal of Ocean Engineering and Technology
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• v.23 no.1
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• pp.158-163
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• 2009

Many longitudinal pipes in ships are subject to considerable loads, caused by hull girder bending in the ships and/or thermal loads in some special pipes through which fluids with highly abnormal temperatures are conveyed. As these loads may cause failure in the pipes or their supporting structures, loops have been widely adopted to prevent such failure, based on the idea that they can lower the stress level in a pipe byabsorbing some portion of these loads. But as the loops also have some negative effects, such as causing extra manufacturing cost, deteriorating the function of the pipe, and occupying extra space, the number and dimensions of these loops need to be minimized. This research developed design formulas for pipe loops, modeling them as a spring element, for which the axial stiffness is calculated based on the beam theory, incorporating the flexibility effect of the straight portion of the pipe. The accuracy of the proposed design formulas was verified by comparing two results obtained from the proposed formulas and MSC/NASTRAN. This paper concludes with a sample application of the proposed formulas, showing their efficiency.

• Smart Structures and Systems
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• v.13 no.6
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• pp.1041-1063
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• 2014

This work introduces a two-module robotic pipe inspection system with ultrasonic NDE device to evaluate the integrity of pipe structures. The proposed robotic platform has high mobility. The two module mobile robot platform overcomes pipe obstacle structures such as elbow, or T-branch joints by cooperative maneuvers. Also, it can climb up the straight pipeline at a fast speed due to the wheel driven mechanism. For inspection of pipe structure, SH-waves generated by EMAT are applied with additional signal processing methods. A wavelet transform is implemented to extract a meaningful and specific signal from the superposed SH-wave signals. Intensity ratio which is normalized the defect signals intensity by the maximum intensity of directly transmitted signals in the wavelet transforms spectrum is applied to evaluate defects quantitatively. It is experimentally verified that the robotic ultrasonic inspection system with EMAT is capable of non-destructive inspection and evaluation of defects in pipe structure successfully by applying signal processing method based on wavelet transform.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.10
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• pp.1450-1456
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• 2003

Three-dimensional pipe flows with elbows, tees and headers in three different pipe systems are calculated to estimate the effect of asymmetry of axial velocity profile and swirl on measuring accuracy of an orifice flowmeter. It is evaluated how the pressure difference across the orifice is dependent on the upstream straight pipe length and how swirl intensity, swirl angle, and axial velocity distribution affect the measuring error of the orifice flowmeter. From the results, it is found that variation of the pressure difference across the orifice is negligible in case that maximum swirl angle is less than 2$^{\circ}$, and also that the pressure difference across the orifice is more sensitive to the asymmetry of axial velocity profile rather than the swirl intensity.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.12 s.243
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• pp.1574-1585
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• 2005

In this paper, a spectral element model is developed for the uniform straight pipelines conveying internal unsteady fluid. Four coupled pipe-dynamics equations are derived first by using the Hamilton's principle and the principles of fluid mechanics. The transverse displacement, the axial displacement, the fluid pressure and the fluid velocity are all considered as the dependent variables. The coupled pipe-dynamics equations are then linearized about the steady state values of the fluid pressure and velocity. As the final step, the spectral element model represented by the exact dynamic stiffness matrix, which is often called spectral element matrix, is formulated by using the frequency-domain solutions of the linearized pipe-dynamics equations. The FFT-based spectral dynamic analyses are conducted to evaluate the accuracy of the present spectral element model and also to investigate the structural dynamic characteristics and the internal fluid transients of an example pipeline system.

• The KSFM Journal of Fluid Machinery
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• v.13 no.3
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• pp.54-58
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• 2010

The pneumatic waste collection system, which is a complete solution for solving the waste collection problems, are constructed in many countries all over the world. However, research data for piping network design are insufficient. In this paper the pressure losses of the straight and curved pipes, pipe junctions are obtained using the numerical method in order to investigate the optimal pipe network design for the waste collection system. As an experimental result, the length of 1.8 meter is the reasonable for the radius of curvature of a curved pipe and the angle of 30 degree is suitable for confluent pipe.