• Proceedings of the KSR Conference
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• 2010.06a
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• pp.664-670
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• 2010

The study on mechanical behavior of the structure at the site includes experimental method and numerical analysis method. Experimental method is categorized into true-scale test and laboratory model test. A laboratory model test is to monitor the failure mechanism with a model simulated similar with a real ground so as to identify the quantitative result, while a true-scale model test is the approach which enables to identify the potential problems that may occur with a simulated construction situation similar with a real site circumstance. Thus this study was intended to carry out the experimental test of non open-cut excavation by pipe roof method which is mostly common in domestic sites. as well as was aimed at identifying the ground behavior occurred during pipe penetration using laboratory model test. Appropriate reduced-scale model was selected, taking into account of domestic geological characteristics and operation characteristics of traditional and high-speed rail trains and the qualitative evaluation of displacement was carried out based on a certain ground loss volume depending on excavation after categorizing trackbed settlement pattern by depth of top soil.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.574-579
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• 2011

In this study, we suggested a design modification method to reduce the vibration of an air conditioner for railway vehicles and increase the durability of its pipe lines. Through experimental vibrational mode analyses and structural modifications on the air conditioning system, vibration reduction scheme was suggested and evaluated its effectiveness by empirical modal analysis. The derived design idea was applied to a real air conditioning system and the expected improvement was obtained.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.3
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• pp.1270-1274
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• 2012

The pipe laid underground more than three decades ago are already starting to reveal the problem like corrosion. There have been many studies to design robotic system for a cost-effective revival of old pipes. And the ability to inspect in the pipes, the ability to treat and repaint the pipes and the fault-tolerant robotic system are well known important factors for the robotic system. It's real hard part to manage the underground pipes for companies because it needs high technical and too much money. According to this reasons, in this paper, we had design an in-pipe robotic system having abilities to inspect outworn pipes, to treat and paint old pipes. This new robot system is pressing wall type robot, and it has a good carrying power for working.

• The KSFM Journal of Fluid Machinery
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• v.10 no.4
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• pp.55-60
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• 2007

This paper describes an evaluation method of pressure drop in a circular pipe of waste collection piping system. Accurate pressure drop in a piping system is very important to determine the capacity of turbo blower, which is one of the main elements in the system. Three-dimensional Navier-Stokes analysis is introduced to analyze the pressure drop in the piping system. Organic waste is selected and modeled using the result of site survey performed in an apartment area. Evaluation method of pressure drop used In the present numerical simulation is performed in the shortened pipe line prior to the calculation of the real system. Throughout the numerical simulation, pressure drop in a waste pipe is obtained and compared to the value determined by analytical method. The pressure drop obtained by numerical simulation has a good agreement with that of the analytic method. It is noted that present evaluation method is effective to determine a pressure drop in the piping system. Detailed flow characteristics inside the pipe line are also analyzed and discussed.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.8
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• pp.733-740
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• 2011

This paper deals with the process to identify the transient exciting force generated from a rotary compressor. The compressor was assumed to be a rigid body. The equation of motion of a rigid compressor supported by three mounts was derived with 6 degree-of-freedom. The exciting forces at the center of mass of the compressor were estimated from the acceleration data measured at compressor shell. Compressor-pipe system was modeled numerically. The accelerations of compressor and pipe were predicted numerically by using the estimated exciting force. A new shape of pipe model was proposed to reduce the vibration. In the prediction by the method in this paper, the maximum acceleration of the pipe could be reduced by 53.7 % at the steady-state and by 12 % at the transient process. In the real experiments, the maximum acceleration of the pipe was reduced by 54.2 % at steady-state and 14.7 % at the transient process. It was verified that the numerical results showed good agreement with experimental results.

• The KSFM Journal of Fluid Machinery
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• v.13 no.6
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• pp.36-41
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• 2010

Design, manufacture and calibration procedures of a venturi pipe flowmeter for airflow measurement in altitude engine test were discussed. Altitude engine test using venturi pipe was given as an example. The venturi was designed per the ISO standard of ISO5167, and was intented to include the entire airflow range in the test envelope of the gas turbine engine. Measurement uncertainty analysis was performed in the design procedure to investigate the effect of venturi geometry and sensor specification upon the measurement uncertainty. Manufacturing process was designed to minimize the deviation from the geometry of design. Calibration was performed to get the relationship between the discharge coefficient and the pipe Reynolds number. Then the uncertainty was assessed again using real data acquired during engine test. Through these procedures, it was possible to maintain the uncertainty of airflow measurement under 1 % for most of the operating envelope of the gas turbine engine. The discharge coefficient of the venturi pipe showed agreement with the value suggested in the ISO standard ISO5167-4 within 0.6 %.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.353-354
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• 2006

The automatic inspection system is developed for the formed end part of automotive fuel pipe. The developed system has functions of outer diameter and formed end length measurement by LVDT(linear variable differential transformer) together with burr cleaning of automotive fuel pipe. The measured data are managed and controlled in real time by embedded SPC(statistical process control) program. The system is composed of mechanical part, electronic part and developed software system. These three parts operate automatically by mutual communication with each other. The developed system showed good results in finding inferior goods and efficiency improvement of the fuel pipe production line. It also eliminated the unreliable manual inspection processes and improved the confidence of product quality.

• Magazine of the Korean Society of Agricultural Engineers
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• v.43 no.4
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• pp.69-78
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• 2001

In this study optimal analysis of pipe network was performed using linear and non linear analysis method for complex real pipe network system of Mungyeong water purification field system which consists of 70 nodes and 86 elements. From the examination result of total flow which is distributed to each pipe, it is found that KYPIPE2 Model supplies less amount than NLAM. It is known that dynamic water level and pressure head of KYPIPE2 Model and NLAM are nearly in accordance with each other from each method of the pipe network analyses, and appeared that both methods of analysis shows high reliable result since the distribution of dynamic water level for every node is the short range of EL. 205.0m~EL. 210.0m besides the pressed dynamic water level. The analysis results of pressure in the methods of pipe network analysis for KYPIPE2 Model and NLAM are similar and it is satisfactory result that the pressure distributions of the tab water design criterion of 5.0kgf/cm$^2$ besides the small part of highland.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.5
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• pp.640-647
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• 2004

In order to perform elastic-plastic fracture mechanical analyses, fracture resistance curves for concerned materials are required. The unloading compliance method and the DCPD(Direct Current Potential Drop) method have been widely used for measuring the crack length and the extension for a standard specimen fracture resistance curve test. However it is difficult to apply the unloading compliance method to a real pipe fracture resistance curve test. The objective of this paper is to propose the calibration equation between the normalized crack length and the normalized electric potential, and to apply to pipe fracture experiments. For these, finite element analyses were performed with various current input locations and crack front configurations. Also the 4-point bending jig was manufactured for a pipe test and the DCPD method was used to measure crack extensions and crack lengths for a pipe test. The calculated crack length by the DCPD method agreed with the measured crack length within 5% error.

• Journal of Korean Society of Water and Wastewater
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• v.10 no.4
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• pp.85-93
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• 1996

This study is to make a comparison between the node method and the pipeline method for the analysis of the water distribution systems. For these purposes, the two methods were applied to a pipeline system in series, an artificial distribution network and a real distribution network. The results are as follows. 1. The difference between the results of the two methods was increased with the increase of the hydraulic gradient and the length between two adjacent nodes. 2. When all pipe lengths between two adjacent nodes were larger than 200~300m and have the steep hydraulic gradient, it was found that the results of the two methods showed high differences. 3. The difference between the results of the two methods were negligible in the case of the real distribution system in which only 12% whole pipelines were longer than 30m and the longest pipe length was 850m.