• Journal of the Korean Society for Nondestructive Testing
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• v.23 no.3
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• pp.227-236
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• 2003

Leaks in underground pipelines can cause social, environmental and economical problems. One of relevant countermeasures against leaks is to find and repair of leak points of the pipes. Leak noise is a good source to identify the location of leak points of the pipelines. Although there have been several methods to detect the leak location with leak noise, such as listening rods, hydrophones or ground microphones, they have not been so efficient tools. In this paper, acoustic emission (AE) sensors and accelermeters are used to detect leak locations which could provide all easier and move efficient method. Filtering, signal processing and algorithm of raw input data from sensors for the detection of leak location are described. A 120m-long pipeline system for experiment is installed and the results with the system show that the algorithm with the AE sensors and accelerometers offers accurate pinpointing of leaks. Theoretical analysis of sound wave propagation speed of water in underground pipes, which is critically important in leak locating, is also described.

• Journal of Energy Engineering
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• v.28 no.1
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• pp.22-29
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• 2019

A heat pump system using wasted heat from thermal effluent to supply the heating energy can reduce energy consumption and emissions of greenhouse gases by greenhouse facilities nearby. The Jeju National University consortium constructed a heat pump system using the thermal effluent from the Jeju thermal power plant of KOMIPO to provide with cool or hot water to greenhouse facilities located 3 km from the power station. In this paper, the system configuration of the heat pump system was summarized, and the results of operations for demonstration of a heating performance carried out during the winter season in 2018 were investigated. The preoperational tests proved that the water temperature drop through the pipeline transporting extracted heat was less than $2^{\circ}C$. The COP (coefficient of performance) of the heat pump was higher than 4.0, and hot water with the maximum temperature of $50^{\circ}C$ could be supplied to greenhouse facilities by utilizing wasted heat from thermal effluent.

• Journal of Internet of Things and Convergence
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• v.8 no.5
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• pp.11-16
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• 2022

As an interest in the development of artificial intelligence(AI) technology in the water supply sector increases, we have developed an AI algorithm that can predict improvement decision-making ratings through repetitive learning using the data of pipe condition evaluation results, and present the most reliable prediction model through a verification process. We have developed the algorithm that can predict pipe ratings by pre-processing 12 indirect evaluation items based on the 2020 Han River Basin's basic plan and applying the AI algorithm to update weighting factors through backpropagation. This method ensured that the concordance rate between the direct evaluation result value and the calculated result value through repetitive learning and verification was more than 90%. As a result of the algorithm accuracy verification process, it was confirmed that all water pipe type data were evenly distributed, and the more learning data, the higher prediction accuracy. If data from all across the country is collected, the reliability of the prediction technique for pipe ratings using AI algorithm will be improved, and therefore, it is expected that the AI algorithm will play a role in supporting decision-making in the objective evaluation of the condition of aging pipes.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.4
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• pp.437-442
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• 2010

Flow-accelerated corrosion (FAC) leads to thinning of steel pipe walls that are exposed to flowing water or wet steam. From experience, it is seen that FAC damage to piping at fossil and nuclear plants can result in outages that require expensive repairs and can affect plant reliability and safety. CHECWORKS have been utilized in domestic nuclear plants as a predictive tool to assist FAC engineers in planning inspections and evaluating the inspection data so that piping failures caused by FAC can be prevented. However, CHECWORKS may be occasionally ignore local susceptible portions when predicting FAC damage in a group of pipelines after constructing a database for all the secondary side piping in nuclear plants. This paper describes the methodologies that can complement CHECWORKS and the verifications of CHECWORKS prediction results using numerical analysis. FAC susceptible locations determined using CHECWORKS for two pipeline groups of a nuclear plant was compared with determined using the numerical-analysis-based FLUENT.

• Journal of the Korean Association of Geographic Information Studies
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• v.9 no.2
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• pp.11-19
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• 2006

Sewerage is the system that improves the quality of human life and prevents many disasters such as floods. However the investigators in Korea only have been concerned about the sewer system, so the sewage treatment plant stays in the basic level like mapping. For example, only one attribute can be recognized in the linear object. Because of this limitation, it makes difficult to manage the linear attribute regarding to the sewage pipe plan. And it is impossible to control a partial (point type, line type) attribute changes of the linear object. We will therefore present the applicable method for the attribute changes of the linear object like the sewage pipe plans. For this reason, this paper is designed on the basis of Dynamic Segmentation(DS). DS has the advantage of giving the attribute value to the exact place in the linear object. As a result of using DS, the variety environment changes around the sewage pipes are applied to the building sewerage data. This also makes it possible to get a precise estimation for the maximum dirty water amount.

• The Journal of the Korea Contents Association
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• v.16 no.4
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• pp.614-623
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• 2016

Grid(pipe network) design is an important element of Smart Water Grid, which essential to estimate hydraulic parameters such as the pressure, friction factor, friction velocity, head loss and energy slope. Especially, friction velocity in a grid is an important factor in conjunction with energy gradient, friction coefficient, pressure and head loss. However, accurate estimation friction head loss, friction velocity and friction factor are very difficult. The empirical friction factor is still estimated by using theory and equation which were developed one hundred years ago. Therefore, in this paper, new equation from maximum velocity and friction velocity is developed by using integration relationship between Darcy-Weisbach's friction head loss equation and Schlichting equation and regression analysis. To prove the developed equation, smooth pipe data areis used. Proposed equation shows high accuracy compared to observed data. Study results are expected to be used in stability improvements and design in a grid.

• Corrosion Science and Technology
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• v.19 no.3
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• pp.122-130
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• 2020

In this study, a corrosion failure analysis of a heat transport pipe was conducted, as the result of a pinhole leak. Interestingly, the corrosion damage occurred externally in the pipeline, resulting in severe thickness reduction near the seam line. Also, while a stable magnetite protective film formed on the inner surface, the manganese oxide formation occurred only on the outer surface. The interior and exterior of the pipe were composed of ferrite and pearlite. The large manganese sulfide and alumina inclusions were found near the seam line. In addition, the manganese sulfide inclusions resulted in grooving corrosion, which progressed in the seam line leading to the reduction in the thickness, followed by the exposure of the alumina in the matrix to the outer surface. To note, the corrosion was accelerated by pits generated from the boundaries separating the inclusions from the matrix, which resulted in pinhole leaks and water loss.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.13 no.5
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• pp.452-459
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• 2020

The electric actuator receives the user's command input signal (open/closed/stop), checks the status of various sensors (valve position, rotational force, motor status, etc.)in the actuator, and controls the motor forward/reverse to open and close the valve. It is a device that outputs the current state of an actuator (valve) and is used in various fields such as dams, power plants, water and sewage facilities, and oil pipeline facilities. If an electric actuator is installed in a power plant and a problem occurs during operation, it can cause a large economic loss, so system reliability is vert important. In this study, in order to increase the safety of the electric actuator, the development of an electric actuator control device capable of setting the ON/OFF time in hardware was conducted to solve the reliability problem that may occur in software. In addition, the electric actuator control device development environment was developed using Xilinx's Spartan7 FPGA and Altium tool.

• Journal of the Korean GEO-environmental Society
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• v.16 no.6
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• pp.31-38
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• 2015

Recently, the participation on the development of the natural gas pipeline in Russia as well as the recent construction of the second Korean Antarctic research station, the Jangbogo station provide the research interests on the behavior of the permafrost ground. To investigate the effect of fines on the mechanical responses of frozen sands, unconfined compression tests were performed on the frozen sands with 0, 5, 10 and 15% of fine contents at -5, -10 and $-15^{\circ}C$. The poorly graded (SP) Joomunjin sand and kaolinite, silt with low plasticity (ML) were used for the preparation of the frozen soil specimens. The mechanical responses of the tested soils were investigated via unconfined compression tests in the temperature controlled laboratory and analyzed in terms of peak unconfined compressive strength and secant modulus at 50% of the peak strength. As the fine contents increase, the unfrozen water contents increase and thus the strength and stiffness of frozen soils decrease. The increment of the stiffness and strength due to the temperature decrease vary with the fine contents.

• Ocean Systems Engineering
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• v.8 no.4
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• pp.427-439
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• 2018

Floating Production Storage and Offloading (FPSO) units have the advantages of their ability to provide storage and offloading capabilities which are not available in other types of floating production systems. In addition, FPSOs also provide a large deck area and substantial topsides payload capacity. They are in use in a variety of water depths and environments around the world. It is a good solution for offshore oil and gas development in fields where there is lack of an export pipeline system to shore. However due to their inherently high motions in waves, they are limited in the types of risers they can host. The Low Motion FPSO (LM-FPSO) is a novel design that is developed to maintain the advantages of the conventional FPSOs while offering significantly lower motion responses. The LM-FPSO design generally consists of a box-shape hull with large storage capacity, a free-hanging solid ballast tank (SBT) located certain distance below the hull keel, a few groups of tendons arranged to connect the SBT to the hull, a mooring system for station keeping, and a riser system. The addition of SBT to the floater results in a significant increase in heave, roll and pitch natural periods, mainly through the mass and added mass of the SBT, which significantly reduces motions in the wave frequency range. Model tests were performed at the Korea Research Institute of Ships & Ocean Engineering (KRISO) in the fall of 2016. An analytical model of the basin model (MOM) was created in Orcaflex and calibrated against the basin-model. Good agreement is achieved between global performance results from MOM's predictions and basin model measurements. The model test measurements have further verified the superior motion response of LM-FPSO. In this paper, numerical results are presented to demonstrate the comparison and correlation of the MOM results with model test measurements. The verification of the superior motion response through model test measurements is also presented in this paper.