• Journal of Energy Engineering
• /
• v.17 no.4
• /
• pp.204-211
• /
• 2008

Polyethylene(PE) pipes have been widely used as they are easy to construct and suitable for economical efficient when they are compared with metal pipelines. This paper studied the effect of various external loadings on stress and deflection of the buried PE pipes using Finite Element Method(FEM). For this purpose, stresses of buried PE pipes were calculated according to the loading condition such as pipe types(pipe diameter $50{\sim}400mm$), burial depths($0.6{\sim}1.2m$) and internal pressures($0.4{\sim}4bar$). As a result, it was founded the effect and relation with each of loading conditions under the buried condition.

• Journal of Animal Environmental Science
• /
• v.3 no.2
• /
• pp.87-95
• /
• 1997

This study was peformed to compare work routine time and performance of milking systems by measuring motion and time in milking procedure. Data were collected from thirteen dairy farms among which milking was done by bucket in two farms, by pipelines in three, by tandem parlors in four including one remodeled side-opening, by herringborn parlors in three and by a parallel milking parlor. Recording time and motion for milking parlor. Recording time and motion for milking procedure was performed by stopwatch and notebook computer. Work routine elements were recorded and calculated into cows milked per-man-hour(CMPH). The results are as follows : Average milking time per cow(MTPC) in bucket and pipeline milking systems usually installed in cow stall were 442.7 and 395.8 seconds, respectively. And average CMPH of bucket and pipeline milking system were 144.5, 303.3, 272.5 and 380.3 seconds, respectively. And CMPH of tandem, herringbone, parallel and modified side-opening systems were 24.9, 11.9, 13.2 and 9.5 heads, respectively. CMPH was the highest in the tandem milking system and the lowest in the bucket milking facilities. CMPH, when milked in a parlor resulted in high value compared with bucket or pipeline milking systems installed in cow stable. They showed considerably low CMPH compared with the results of other countries. The reason why so low CMPH could be derived from type and mechanization of facilities and equipment, operator's ability, number of operator, idle time and milking procedure.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.4
• /
• pp.2401-2406
• /
• 2015

Pipelines are used by large heavy industries to deliver various types of fluids. Since this is important to maintain the performance of large systems, it is necessary to accurately predict remaining life of the corroded pipeline. However, predicting the remaining life is difficult due to uncertainties in the associated variables, such as geometries, material properties, corrosion rate, etc. In this paper, a statistical method for predicting corrosion remaining life is proposed using Bayesian inference. To accomplish this, pipeline failure probability was calculated using prior information about pipeline failure pressure according to elapsed time, and the given experimental data based on Bayes' rule. The corrosion remaining life was calculated as the elapsed time with 10 % failure probability. Using 10 and 50 samples generated from random variables affecting the corrosion of the pipe, the pipeline failure probability was estimated, after which the estimated remaining useful life was compared with the assumed true remaining useful life.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.20 no.5
• /
• pp.58-65
• /
• 2016

Recent frequent occurrence of urban sinkhole serves as a momentum of the periodic inspection of sewer pipelines. Sewer inspection using a CCTV device needs a lot of time and efforts. Many of previous studies which reduce the laborious tasks are mainly interested in the developments of image processing S/W and inspection H/W. However there has been no attempt to find meaningful information from the existing CCTV images stored by the sewer maintenance manager. This study adopts a cross-correlation based image processing method and extracts location data of sewer inspection device from CCTV images. As a result of the analysis of time-location relation, it shows strong correlation between the device's stand times and the sewer damages. In case of using this method to investigate sewer inspection CCTV images, it will save the investigator's efforts and improve the sewer maintenance efficiency and reliability.

• Journal of the Korean Geotechnical Society
• /
• v.30 no.8
• /
• pp.39-47
• /
• 2014

Frost heaving and thawing settlement cause unexpected stress around buried pipelines, which results in deformation and permanent demage. A large scale laboratory test has been performed to observe deformation, stress, and temperature of a buried pipe during atmospheric temperature changes. From the experimental results, the stress concentrated around the buried pipe is inevitable and deformation is caused by the frost heaving. Even though backfill materials are sandy soils which are normally assumed to be non frost susceptible, it is revealed that frost demage can happen due to drainage condition, the level of ground water table, and water content.

• Journal of the Korean Academic Society of Industrial Cluster
• /
• v.2 no.1
• /
• pp.14-27
• /
• 2008

Ousters have become a key focus of interest and analysis over the last decade or so, informed by the work of the Harvard business economist Michael Porter. Recent research, however, suggests that the classic Porterian conception of clusters needs to be rethought. In particular, the idea that clusters are geogaphically bounded and integrated units whose primary link to the outside world is through the export of goods and services to global markets is highly Questionable, if not untenable. Relational approaches to clusters and regional development stress the importance of the wider networks and 'pipelines' through which knowledge is exchanged with key partners and collaborators located outside of the particular cluster in question. Rather than the main external links being those between leading firms and global markets, firms may engage in a range of global relations with collaborators and suppliers. This paper address the challenge of rethinking clusters in the light of the recent emphasis on global networks md connections, drawing on experience from m old industrial region in Western Europe Scotland. In assessing cluster experiences and initiatives in Scotland, I examine the development of the oil and gas and electronics clusters. In conclusion, I suggest that cluster initiatives me only likely to generate lasting benefits for the region in question if there is significant local ownership md control of key industries and clusters.

• The Bulletin of The Korean Astronomical Society
• /
• v.36 no.2
• /
• pp.129.1-129.1
• /
• 2011

We have applied an advanced multi-aperture indexing photometry and sophisticated de-trending method to existing Taiwanese-American Occultation Survey (TAOS) data sets. TAOS, a wide-field ($3^{\circ}{\times}3^{\circ}$) and rapid photometry (5Hz) survey, is designed to detect small objects in the Kuiper Belt. Since TAOS has fast and multiple exposures per zipper mode image, point spread function (PSF) varies in a given image. Selecting appropriate aperture among various size apertures allows us to reflect these variations in each light curve. The survey data turned out to contain various trends such as telescope vibration, CCD noise, and unstable local weather. We select multiple sets of stars using a hierarchical clustering algorithm in such a way that the light curves in each cluster show strong correlations between them. We then determine a primary trend (PT) per cluster using a weighted sum of the normalized light curves, and we use the constructed PTs to remove trends in individual light curves. After removing the trend, we can get each synthetic light curve of star that has much higher signal-to-noise ratio. We compare the efficiency of the synthetic light curves with the efficiency of light curves made by previous existing photometry pipelines. Our photometric method is able to restore subtle brightness variation that tends to be missed in conventional aperture photometric methods, and can be applied to other wide-field surveys suffering from PSF variations and trends. We are developing an analysis package for the next generation TAOS survey (TAOS II) based on the current experiments.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.17 no.1
• /
• pp.34-41
• /
• 2018

A flange joint is a pipe connection used to prevent the leakage of high-pressure fluids by inserting a gasket and tightening the bolts. Among several kinds of gaskets available, metal ring type joint gaskets are most widely used in conditions that require high-temperature and high-pressure fluid flow, such as oil pipelines, gas pipes, pumps, valve joints, etc. The purpose of this study is to investigate the contact pressure and stress characteristics closely related to the sealing performance of Class 900 flange joints used in high temperature and high pressure environments. The dimensions of flange joints with five different nominal pipe sizes were determined with reference to those specified in ASME 16.5. The metal ring gaskets inserted in the joints were octagonal and oval gaskets. The bolt tensile forces calculated from the tightening torques were input as the bolt pretension loads in order to determine the contact pressure and stress levels after fastening. Loading was composed of three steps, including the fastening step, and different amounts of applied pressures were used in each analysis to investigate the effect of fluid pressure on the contact force of the joints. A general-purpose software, ANSYS 17.2, was used for the analysis.

• Journal of the Korean Magnetics Society
• /
• v.24 no.6
• /
• pp.171-178
• /
• 2014

Remote Field Eddy Current Testing (RFECT), one of the ways which is a nondestructive testing using electromagnetic fields, can make up for Magnetic Flux Leakage (MFL) weaknesses and general Eddy Current Testing (ECT) weaknesses which is an occurrence of a huge friction force or disadvantage of detecting defects on the outer wall. So many of institutes and laboratories have studied on RFECT for the past 50 years. But There is a lack of discussion about a study on eddy current and magnetic field distributions in a pipe wall and designing of RFECT exciter coil. In this paper, eddy current and magnetic field distributions in a pipe wall and influence of altering variables are analyzed. Also, the optimal design algorithm about the RFECT Exciter coil are proposed, and influence on defect signals caused by alteration of its shape is analyzed.

• Journal of the Society of Naval Architects of Korea
• /
• v.57 no.4
• /
• pp.191-197
• /
• 2020

Pipe routing is a important part of the whole design process in the shipbuilding industry. It has a lot of constraints and many tasks that should be considered together. Also, the result of this stage affects follow-up works in a wide scope. Therefore, this part requires skilled designers and a lot of time. This study aims to reduce the workload and time during the design process by automating the pipe route design on initial stage. In this study, the reinforcement learning was used for pipe auto-routing. Reinforcement learning has the advantage of dynamically selecting routes, unlike existing algorithms. Therefore, it is suitable for the pipe routing design in ship design process which is frequently modified. At last, the effectiveness of this study was verified by comparing pipelines which were designed by piping designer and reinforcement learning results.