• Journal of Korean Society of Water and Wastewater
• /
• v.37 no.6
• /
• pp.347-361
• /
• 2023

Water utilities are making various efforts to reduce water losses from water networks, and an essential part of them is to recognize the moment when a pipe burst occurs during operation quickly. Several physics-based methods and data-driven analysis are applied using real-time flow and pressure data measured through a SCADA system or smart meters, and methodologies based on machining learning are currently widely studied. Water utilities should apply various approaches together to increase pipe burst detection. The most intuitive and explainable water balance method and its procedure were presented in this study, and the applicability and detection performance were evaluated by applying this approach to water supply pipelines. Based on these results, water utilities can establish a mass balance-based pipe burst detection system, give a guideline for installing new flow meters, and set the detection parameters with expected performance. The performance of the water balance analysis method is affected by the water network operation conditions, the characteristics of the installed flow meter, and event data, so there is a limit to the general use of the results in all sites. Therefore, water utilities should accumulate experience by applying the water balance method in more fields.

• Smart Structures and Systems
• /
• v.21 no.6
• /
• pp.761-776
• /
• 2018

Guided wave testing is a reliable and safe method for pipeline inspection. In general, guided wave testing employs a circumferential array of piezoelectric transducers to clamp on the pipe circumference. The sensitivity of the operation depends on many factors, including transducer distribution across the circumferential array. This paper presents the sensitivity analysis of transducer array for the circumferential characteristics of guided waves in a pipe using finite element modelling and experimental studies. Various cases are investigated for the outputs of guided waves in the numerical simulations, including the number of transducers per array, transducer excitation variability and variations in transducer spacing. The effect of the dimensions of simulated notches in the pipe is also investigated for different arrangements of the transducer array. The results from the finite element numerical simulations are then compared with the related experimental results. Results show that the numerical outputs agree well with the experimental data, and the guided wave mode T(0,1) presents high sensitivity to the notch size in the circumferential direction, but low sensitivity to the notch size in the axial direction.

• Smart Structures and Systems
• /
• v.30 no.2
• /
• pp.173-181
• /
• 2022

The current paper presents a technique to detect crack in non-uniform cantilever-type pipe beams, that have step changes in the properties of their cross sections, restrained by a translational and rotational spring with a tip mass at the free end. An equation for estimating the natural frequencies for the non-uniform beams is derived using the boundary and continuity conditions, and an equivalent bending stiffness for cracked beam is applied to calculate the natural frequencies of the cracked beam. An experimental study for a step-changed non-uniform cantilever-type pipe beam restrained by bolts with a tip mass is carried out to verify the proposed method. The translational and rotational spring constants are updated using the neural network technique to the results of the experiment for intact case in order to establish a baseline model for the subsequent crack detection. Then, several numerical simulations for the specimen are carried out using the derived equation for estimating the natural frequencies of the cracked beam to construct a set of training patterns of a neural network. The crack locations and sizes are identified using the trained neural network for the 5 damage cases. It is found that the crack locations and sizes are reasonably well estimated from a practical point of view. And it is considered that the usefulness of the proposed method for structural health monitoring of the step-changed non-uniform cantilever-type pipe beam-like structures elastically restrained in the ground and have a tip mass at the free end could be verified.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2005.04a
• /
• pp.416-421
• /
• 2005

Concrete are brittle materials and they are which come to brittle fracture rapidly by progress of cracks. Therefore, what the time for repairing the damage portion is understands importantly by such cracks. When they happened the glass pipe similar to concrete was used. Such a glass pipe can insert repair material in an inside, or can use it by switch. They are interested in the crack monitoring of structure using FM radio sensor and PZT sensor. In this study, the monitoring to a crack was studied using FM radio sensor and PZT sensor. Therefore, the purpose of this study is the fundamental research which detects damages of main members using the compound sensor which consisted of the radio sensors of resistance, PZT, and FM system.

• Smart Structures and Systems
• /
• v.3 no.3
• /
• pp.357-372
• /
• 2007

Parametric density concept is proposed for a long-range pipeline health monitoring. This concept is designed to obtain the attenuation of ultrasonic guided waves propagating in underwater pipelines without complicated calculation of attenuation dispersion curves. For the study, three different pipe materials such as aluminum, cast iron, and steel are considered, ten different transporting fluids are assumed, and four different geometric pipe dimensions are adopted. It is shown that the attenuation values based on the parametric density concept reasonably match with the attenuation values obtained from dispersion curves; hence, its efficiency is proved. With this concept, field engineers or inspectors associated with long-range pipeline health monitoring would take the advantage of easier capturing wave attenuation value, which is a critical variable to decide sensor location or sensors interval.

• Smart Structures and Systems
• /
• v.19 no.5
• /
• pp.473-485
• /
• 2017

Ratcheting behavior of $90^{\circ}$ elbow piping subject to internal pressure 20 MPa and reversed bending 20 kN was investigated using experimental method. The maximum ratcheting strain was found in the circumferential direction of intrados. Ratcheting strain at flanks was also very large. Moreover, the effect of temperature on ratcheting strain of $90^{\circ}$ elbow piping was studied through finite element analysis, and the results were compared with room condition ($25^{\circ}$). The results revealed that ratcheting strain of $90^{\circ}$ elbow piping increased with increasing temperature. Ratcheting boundary of $90^{\circ}$ elbow piping was determined by Chaboche model combined with C-TDF method. The results revealed that there was no relationship between the dimensionless form of ratcheting boundary and temperature.

• Proceedings of the Korean Society of Computer Information Conference
• /
• 2015.07a
• /
• pp.327-328
• /
• 2015

본 논문은 지하공동구에서의 출입자의 통제를 위해 스마트폰을 이용한 출입관리시스템을 제안한다. 제안하는 시스템은 지하공동구 자동개폐기의 MCU를 통해 온습도, 개폐기의 상태, 출입자의 기록 등 다양한 정보를 취득하여 관리한다. 이때 취득한 정보는 블루투스4.0 모듈을 통해 ECB 암호화 방식을 사용하여 스마트폰에 전송한다. 본 논문에서 제안하는 출입관리시스템은 기존 물리적인 키에 의존하던 출입 방식을 대체하여 신뢰성 있는 보안 및 체계적인 관리가 가능할 것으로 기대한다.

• International journal of advanced smart convergence
• /
• v.10 no.2
• /
• pp.15-20
• /
• 2021

We constructed an air-lifted seawater propulsion system for decreasing fuel consumption of the ships. The system has a form of pipes which can be easily installed on the sides of the ship. Seawater mixed with air, will rise along within the pipe, and will be discharged downward. If the directions of inlet / outlet of the pipe are designed properly, a propulsive energy can be obtained. We tested the system with a model ship in Jangsa port at Sokcho-city with a water depth of 2.5 meters. The system was supplied regulated air at 6 bars during the 3 tests. The model ship was moving forward at a rate of 0.18 meters per second. In case of large ships equipped zfrom clean energy.

• The Journal of the Korea Contents Association
• /
• v.9 no.12
• /
• pp.477-484
• /
• 2009

It is important for the strategy of service to provide the weather information in the environment that the smart clothing has been changed focusing on the consumer center. Recently, the various applications of smart clothing concept have been presented by researchers and developers. Among them, the smart clothing based on the sensors is most likely to gain the highest demand rate in the market. In this paper, we proposed the life weather index monitoring system using the wearable based smart cap. By wearing the proposed smart cap, the weather status is gathered and its signals are transmitted to the connected UMPC. It can be easily monitored in real time. To provide the life weather index according to the sensors, the weather index was analyzed in terms of 6 factors, such as, the heat index, the food poisoning index, the discomfort index, the ultraviolet index, the water pipe freeze possibility index, and the windchill temperature index. Ultimately, this paper suggests empirical application to verify the adequacy and the validity with the life weather index monitoring system. Accordingly, the satisfaction and the quality of services will be improved the smart clothing.

• Journal of Convergence for Information Technology
• /
• v.9 no.7
• /
• pp.78-84
• /
• 2019

The purpose of this study is to introduce the concept of the Smart Sewer System and to analyze the economic ripple effect when smart sewer is built all over Korea. The research method is the input-output model based on the assumption that the smart sewerage will be constructed throughout the Korea from 2021 to 2040. Estimation results show that the production-induced effect reaches 343.73 trillion Korean won, the added value-induced effect is 155.867 trillion Korean won, and the employment-induced effect is estimated by 25,118,470, indicating that the smart sewer project leads to being considerably large in the nation-wide economy. In addition, the increase of social welfare by smart sewer is expected to be realized through the improvement of both the environment improvement and the national health. Therefore, the smart sewer project should be implemented without delay by planning a concrete road map and putting it into effect with a budget.