• Nuclear Engineering and Technology
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• v.32 no.1
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• pp.46-56
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• 2000

Numerical results are presented for the 2-dimensional turbulent transient heat transfer of the shell/tube heat exchanger with a step change of the inlet temperature in the primary side. Heat transfer boundary conditions outside the pipe are given partially by the convection heat transfer conditions and partially by insulated conditions. Calculation results were obtained by solving the unsteady two-dimensional elliptic forms for the Reynolds-averaged governing equations for the mass, momentum and energy. Finite-difference method was used to obtain discretization equations, and the SIMPLER solution algorithm was employed for the calculation procedure. Turbulent model used is the algebraic model proposed by Cebeci-Smith. Results presented include the time variant Nusselt number distribution, average temperature distribution and outlet temperatures for the various inlet temperatures and flow rates.

• Journal of Ocean Engineering and Technology
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• v.23 no.4
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• pp.85-90
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• 2009

Although most of existing hydration heat control methods show a certain degree of hydration heat control, generally, there are many problems as mentioned above. Therefore, our laboratory previously developed a hydration heat control method using an exposed heat pipe, which solves most of these problems and simultaneously displays excellent hydration heat control. Unfortunately, even this method had some problems such as the processing, transport, and assembly of heat pipes, and the surface treatment of a cut plane after pouring, and hardening concrete. Therefore, in this study, a hydration heat control method using an embedded pipe has been developed with the expectation that this method solves those problems in hydration heat control using an exposed heat pipe. As a result of the experiment, the peak temperature of ECHP and ICHP specimen about $4.5{\sim}6.5^{\circ}C$ than the OPC specimen and the probability of thermal cracked generated in ECHP and ICHP specimen decreased up to $13{\sim}20%$. Finally, it was confirmed in this study that the hydration heat control method using an embedded heat pipe is significantly more superior and cost effective than the existing method of an exposed one.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.9
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• pp.930-937
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• 2009

The estimation method of the fracture resistance curve for the pipe specimen was proposed using the load ratio method for the standard specimen. For this, the calculation method of the load - CMOD curve for the pipe specimen with the common format equation(CFE) was proposed by using data of the CT specimen. The proposed method agreed well with experimental data. The J-integral value and the crack extension were calculated from the estimated load - CMOD data. The fracture resistance curve was estimated from the calculated J-integral and the crack extension. From these results, it have been seen that the proposed method is reliable to estimate the J-R curve of the pipe specimen.

• 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.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.1
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• pp.109-117
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• 2012

This paper addresses influence on the flow field by varying the length of DPF Inlet pipe in 5 ways. Numerical analysis is carried out by using PIV and commercial code and as a result, PIV and commercial code shows correlation correspond to 87%. Furthermore, in the same velocity condition, as stable and high pressure value is shown when the Inlet pipe length is 20mm, particulate filtering rate can be increased.

• Solar Energy
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• v.9 no.1
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• pp.43-52
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• 1989

Heat transfer rate and heat flux from the condenser with internally triangular fins rotating heat pipe has been numerically studied by finite element method. The results of numerical and P.J. Martos' experimental showed good agreement and it was able to predict to the performance of a rotating heat pipe. By increasing fin half angle or fin height, heat transfer rate from condenser was increased slightly but heat flux was decreased. By increasing condenser radius or r.p.m. of rotating heat pipe, heat transfer rate and heat flux was increased rapidly. Heat transfer rate was rapidly increased with increasing fin numbers in case of few fm numbers but slowly increased at many fin numbers. So the optimum fin numbers were a half of maximum fin numbers which was able to install in the condenser of a rotating heat pipe.

• Journal of Environmental Health Sciences
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• v.33 no.1 s.94
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• pp.43-48
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• 2007

This study investigated the effects of pH, alkalinity, and chlorine ion which are important water quality impact factors to the corrosion in the simulated distribution system where the copper pipe is affixed. The result shows that pitting index was increased as the alkalinity and chloride ion increase in the distilled water, but there was no relation to pH. Actually the uniform corrosion rate was decreased as the pH increase with the laboratory tap water. In conclusion, it is necessary to control the pH which stands above minimum 7.5 to prevent pitting corrosion in the copper pipe. Consequently, comprehensive research about the effect of lime soda($Ca(OH)_2$) which was used as a coagulation additive in the water treatment plant to pipe corrosion must be accomplished additionally.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.11
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• pp.4075-4079
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• 2010

In this paper, structural analysis was conducted by ANSYS code for three dimensional finite element method to the pipe butt welding machine. Based on this numerical structural analysis, stress, strain and total deformation were obtained and the design change of the pipe butt welding machine was made along with improved productivity and shorten design period.

• Geomechanics and Engineering
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• v.24 no.4
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• pp.337-348
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• 2021

Brillouin Optical Frequency Domain Analysis (BOFDA) is a distributed fiber optic sensing (DFOS) technique that has unique advantages for performance monitoring of piles. However, the complicated production process and harsh operating environment of offshore PHC pipe piles make it difficult to apply this method to pile load testing. In this study, sensing cables were successfully pre-installed into an offshore PHC pipe pile directly for the first time and the BOFDA technique was used for in-situ monitoring of the pile under axial load. High-resolution strain and internal force distributions along the pile were obtained by the BOFDA sensing system. A finite element analysis incorporating the Degradation and Hardening Hyperbolic Model (DHHM) was carried out to evaluate and predict the performance of the pile, which provides an improved insight into the offshore pile-soil interaction mechanism.

• Advances in Energy Research
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• v.4 no.4
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• pp.299-323
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• 2016

Cylindrical parabolic solar concentrators of small concentration ratio are attractive options for working temperatures around $120^{\circ}C$. The heat gained can be utilized in many applications such as air conditioning, space heating, heating water and many others. These collectors can be easily manufactured and do not need to track the sun continuously. Using a heat pipe as a solar absorber makes the system more compact and easy to install. This study is devoted to modeling a system of cylindrical parabolic solar concentrators of small concentration ratio (around 5) fitted with a heat pipe absorber with a porous wick. The heat pipe is surrounded by evacuated glass tube to reduce thermal losses from the heat pipe. The liquid and vapor flow equations, energy equation, the internal and external boundary conditions were taken into consideration. The system of equations was solved and the numerical results were validated against available experimental and numerical results. The validated heat pipe model was inserted in an evacuated transparent glass tube as the absorber of the cylindrical parabolic collector. A calculation procedure was developed for the system, a computer program was developed and tested and numerical simulations were realized for the whole system. An experimental solar collector of small concentration, fitted with evacuated tube heat pipe absorber was constructed and instrumented. Experiments were realized with the concentrator axis along the E-W direction. Results of the instantaneous efficiency and heat gain were compared with numerical simulations realized under the same conditions and reasonably good agreement was found.