• Computational Structural Engineering
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• v.2 no.1
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• pp.65-70
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• 1989

An analytical study was conducted using the Galerkin technique to determine behaviour of thin fibrereinforced and laminated composite pipes under soil pressure. Geometric nonlinearity and material linearity have been assumed. It is assumed that vertical and lateral soil pressure are proportional to the depth and lateral displacement of the pipe respectively. It is also assumed that radial shear stress is negligible because the ratio of thickness to the radius of pipe is very small. The above results are verified by the finite element analysis.

• Journal of the Korean Institute of Gas
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• v.2 no.2
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• pp.18-25
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• 1998

According to the requirements of ANSI B3l.8, the pipe thickness is determined with hoop stress resulted from internal pressure. And the other loads induced by soil, vehicle, thermal expansion, ground subsidence, etc shall be evaluated rationally. There are two ways of calculating stress of buried gas pipeline. The first is FEM. FEM can calculate the stress regardless of the complexity of pipeline shape and boundary conditions. But it needs high cost and long time. The second is the way to use equation. The reliable equations to calculate the stress of buried gas pipeline was developed and have been used in designing pipeline and evaluating pipeline safety, But these equation are very difficult to understand and use for non-specialist. For easy calculation of non-specialist, the new computer program to calculate stress of buried natural gas pipeline have been developed. The stress is calculated by the equations and extrapolation of the graph resulted from FEM. The full paper is consist of series I and II. In this paper, series I, the calculating equation of the program is explained in detail.

• 전기의세계
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• v.11
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• pp.56-61
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• 1963

현재 우리나라에서 사용하고 있는 접지전극은 30*30$cm^{2}$의 넓이와 0.7,0.9,1.0,2.0mm의 동판전극들이다. 인건비가 비싸고 전극 자료비가 우리나라에 비하여 싼 외국에서는 접지봉을 많이 사용하고 있다. 접지봉을 사용하면 인건비는 적게들지만 매설하기 위한 기계의 시설비와 같은 접지저항치를 얻기 위한 동량이 판전극 사용시보다 더욱 많이 필요하므로 우리나라 현사정에는 부적당하다. 본 연구의 목적은 소요접지저항을 얻는데 동판전극보다 더욱 경제적인 접지방식을 모색하여 이것과 동판전극방식과의 기술적, 경제적비교검토를 하는데 있다.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2002.05a
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• pp.403-406
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• 2002

가정용 및 산업용으로 사용되고 있는 천연가스는 70kg/cm1의 압력으로 지하에 매설되어 있는 API 5L X65재질의 배관을 통하여 공급되고 있다 생산기지에서 공급되는 압력이 70kg1cmr이지만 가스소비량에 따라 계절별 및 월별 가스 내압이 변화되고 있다. 하루에도 최대 2회정도 주기적으로 변화를 보이고 있다. 본 연구에서는 API 5L X65등급의 가스배관 모재 및 용접부에 일정한 형태의 가우지 결함을 가공하여 현재 사용중인 내압 조건과 유사한 내압변화를 재현하여 피로수명을 평가하였다.(중략)

• Proceedings of the Korean Magnestics Society Conference
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• 2002.12a
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• pp.118-119
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• 2002

실시간으로 매설된 송유관이나 가스관의 내부에 누설자속 (Magnetic Flux Leakage: MFL) 탐지용 피그를 통과시킴으로서 부식을 모니터한다[1]. NdFeB 자석과 같은 강한 영구자석으로 배관을 자화시키면 부식에 의한 결함 근처에서 자속이 누설되고, 그 MFL은 Hall 프로브나 유도코일에 의해 탐지된다. 자기이방성을 이용하여 응력에 의만 누설자속신호 변화를 계산할 수 있다. MFL 신호를 정밀하게 분석하기 위해서는 측정프로브의 측정속도와 내부압력응력과 같은 운용조건을 고려하여야 한다[2]. (중략)

• Journal of Energy Engineering
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• v.21 no.2
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• pp.144-151
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• 2012

A district heating system produces thermal energy and supplies it to a large region. District heating systems can provide higher efficiencies and better pollution control than localized boilers. The heat generated by a district heating system is distributed to the customer via a network of insulated pipes. For the optimal operation of a district heating system, it is important to predict the distributions of pressure, flow rate and temperature of heating fluid within the network of pipes at various operating conditions. In this work, a mathematical modeling was performed to predict the dynamic hydraulic-thermal behaviors of heating fluid in the network of pipes for a district heating system. The mathematical model accounts for the conservations of mass, momentum and energy. In order to verify the validity of modeling, the modeling results were compared with the monitoring data of Gang-nam Branch of District Heating.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.4
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• pp.418-424
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• 2013

Both simulation and physical implementation are valuable tasks in sensor network routing protocols. In this paper, we propose an efficient underground utilities monitoring method within several constraints using wireless sensor network. First, in order to physically implement protocol of network which is applied, the distributed event-based simulation, which applies an existing nesC codes of sensor network routing protocols, is implemented and analyzed. Also, we have performed the simulation and analyzed the execution results for application model of routing protocols for monitoring underground utilities in the VIPTOS(Visual Ptolemy and TinyOS) environments which combine TOSSIM and Ptolemy II based on distributed event.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.4
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• pp.521-531
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• 2001

This paper presents the extraction scheme of the scattered waves by a target above the ground using the buried antenna in a lossy and dispersive medium. The half wave dipole antennas are used to transmit and to receive a signal. The transmission line model as a feeding model is considered to take into account the effect of transmission line in a real system. The ground is modeled by the 2nd order Debye approximation with the dispersion and loss. PLRC algorithm and DPML as absorbing boundary condition are utilized to apply the 2nd order Debye approximation to FDTD. To extract the scattered wave, in addition, we employed the delay time extraction algorithm. The simulations are conducted to observe the variation of magnitude in scattered wave and detection of target position according to the change of moisture content of the lossy medium.

• Journal of Ocean Engineering and Technology
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• v.33 no.2
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• pp.178-188
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• 2019

When burying underwater cables using robots, heading control is one of the key functions for the robots to improve task efficiency. This paper addresses the heading control issue for URI-T, an ROV for underwater construction tasks, including the burial and maintenance of cables or small diameter pipelines. Through modeling and identifying the heading motion of URI-T, the dynamic characteristics and input limitation are analyzed. Based on the identification results, a PD type controller with appropriate input treatment is designed for the heading control of URI-T. The performance of the heading controller was verified in water tank experiments. The field applicability of the proposed controller was also evaluated through the sea trial of URI-T at the East Sea, with a water depth of 500 m.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.204-204
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• 2023

2020년 상수도 통계에 따르면 전국 상수도 보급률은 약 99% 정도로 높은 수치를 기록하고 있으나 노후관으로 인한 관로파손 및 수질사고로 인해 효과적인 운영에는 많은 어려움이 존재한다. 이러한 문제를 해결하기 위해 기술진단 및 정밀안전진단 등 체계적인 유지관리 규정이 도입되었으며 적용되고 있으며, 이때 시스템의 정량적인 성능평가를 위해 간접평가와 직접평가로 구성된 점수평가법이 적용되었다. 간접평가는 지중에 매설된 관로를 대상으로 매설연도, 관경, 관로연장 등의 노후도인자를 통해 관의 노후도를 추정하고 간접평가 결과 3등급으로 판명되는 관로의 경우 객관적인 관의 상태를 평가하기 위해 시편채취 및 관로 내시진단 등의 직접평가가 수행된다. 하지만 관로의 직접평가는 간접평가결과 3등급의 모든 관로에 대해 수행하기에는 진단비용 및 시간 등 제약조건에 따라 모든 지점에 대한 직접평가 수행에는 한계가 있다. 따라서, 본 연구에서는 이러한 관로 성능평가 기법의 한계를 개선하기 위해 상수도시스템 통합평가 기술을 개발하였다. 개발한 기술은 머신러닝 기법을 적용하여 간접평가 및 직접평가 결과를 토대로 직접평가가 필요한 지점의 결과를 예측하였다. 이를 바탕으로 상수도시스템 평가성능 향상 및 보강 우선순위 선정 단계에서 의사결정권자의 판단에 도움이 될 것으로 판단된다.