• Proceedings of the Korean Nuclear Society Conference
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• 1997.05a
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• pp.400-405
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• 1997

산업 현장에서 널리 쓰이는 압축성 유체가 밸브 등을 통하여 원하지 않은 누설이 발생할 경우 그 배관의 외부 온도만을 측정하여 누설량을 개략적으로 구하는 방법을 보였다. 특히 배관라인등 유량 제한 요소가 없는 계통은 Fanno Line 방법을 적용하고 오리피스나 벤추리등 유량 제한 요소가 있을 경우는 노즐 모델링 방법을 적용하면 누설량을 구할수 있고 노즐모델링 방법으로 구한 누설량이 Fanno Line 방법으로 구한 누설량의 약 50%였다.

• Journal of Korean Society of Steel Construction
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• v.21 no.3
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• pp.203-210
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• 2009

If there are some construction works that affect the stability of buried pipelines, the pipelines should be moved to guarantee their safety. In this paper, modeling methods for analyzing the movement of pipelines were sought, and the step-by-step stress estimation method of moving pipelines was developed. Some factors affecting of pipeline response such as the element type, the element size, boundary modeling, and geometric non-linearity were quantitatively investigated. In addition, some conditions in which accuracy and effectiveness can be compromised in the analysis of long pipelines were identified. A neural network was used to estimate the pipeline stress. The inputs to the neural network included step-by-step displacements, and the output was the resulting stress at each movement step. After training the neural network, it can be used to estimate pipeline stresses at some sub-steps that are not included in the training. A Windows-based stress estimation program was developed.

• Journal of the Society of Naval Architects of Korea
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• v.31 no.3
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• pp.19-30
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• 1994

The modeling of a product data is becomming more and more important in engineering environment, especially for the development of CAD/CAM system as a basis of computer integrated manufacturing system. Model is a formalized representation of the real world, and modeling is the task to identify, abstract, and formalize the product information into an unambiguous representation. In this study, the piping system, one of typical product of ship outfitting system, is modeled. The STEP idea is followed to provide a common mechanism to represent the product information throughout the life-cycle, and the object oriented paradigm is used in the analysis and design of the model. The definitions given within this model are independent of the specific application domain so that the same methodology can be used for other purpose.

• 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.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2010.10a
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• pp.312-318
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• 2010

본 연구에서는 배관계에 가해진 압력으로 인하여 변형된 배관에 의하여 영향을 받는 브라켓에 대하여 여러 가지 형상으로 모델링하여 유한요소해석을 통하여 브라켓의 형상변화가 변형특성에 미치는 영향을 고찰 하였고, 배관시스템의 브라켓의 강도 안전성을 확보하기 위하여 산업공학에서 쓰였던 다구찌방법을 도입하여 최적화 설계를 하는 것이 본 연구의 목적이다.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05a
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• pp.221-226
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• 1998

과잉온도 차온(Overtemperature $\Delta$T) 및 과잉출력 차온(Overpower $\Delta$T)트립에 쓰이는 온도 측정계통 총 지연시간은 6초로 구성되며 RTD 우회배관 제거시 4.5초의 RTD 응답시간(일차지연 상수로 가정)과 1.5초의 순수지연시간(전자회로 지연시간 + 그립퍼 풀림시간등)으로 구성된다. 그러나 RTD우회배관 제거전 사고분석을 일차지연상수를 3.5초, 순수지연을 2.5초로 모델링하였으므로 Simulink를 통한 영향분석과 Rack 응답시험 계단파 입력신호의 타당성을 평가하였다. RTD 응답시간은 전형적인 1차 지연요소로 나타내며 계전기나 제어봉 Gripper Release 시간 등은 순수 지연으로 가정하고 분석을 수행하고 기타 지연/지상 필터를 발전소와 동일하게 모델링하여 분석하므로써 발전소에서 일어나는 과도현상을 묘사할 수 있다는 점을 고려할 때 RTD우회배관 제거후 응답시간 지연상수가 바뀌더라도 안전하다는 결론에 도달했다.

• Journal of the Korean Society for Nondestructive Testing
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• v.29 no.5
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• pp.442-449
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• 2009

An investigation has been made on the relationship between characteristics of torsional mode signal in MsS and SH mode signal in BEM modeling for the defect of stainless steel pipe. In order to compare torsional mode signal with SH mode signal of defect in stainless steel pipe, specimens were made by changing size of depth and width along to circumferential direction 360 degrees. All the defects was detected by torsional mode signal of MsS, especially according to the change of depth size, amplitude of signal was changed. But width change for the circumferential defects has no certain tendency. SH mode signal of BEM modeling shows similar results with torsional mode, with change makes amplitude variation of signal. In this paper, the characteristics of torsional mode and SH mode signals were found. It is possible to predict the circumferential defects for the pipe by SH mode modeling.

• Journal of the Korean Institute of Gas
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• v.2 no.1
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• pp.23-27
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• 1998

To protect the underground pipeline from the mechanical damage and to enhance the cathodic protection effect, the river sand has been backfilled traditionally around the buried pipeline. However, river sand became depleted and expensive. One has to seek for the economic alternative materials. Crashed stone is a good candidate for the backfill material. In this study, how much the particle size and shape of the crashed stone can effect on the gas pipeline coating was examined. A series of laboratory and field test was performed. In the Lab, the increasing loads were applied to the coated pipeline surrounded by the crashed stone, where no significant damage was observed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1996.04a
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• pp.215-220
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• 1996

원자력발전소의 주증기관은 증기발생기와 터빈을 연결하는 주요 계통으로서 여기서 발생하는 배관진동은 주요기기의 연결부, 밸브, 배관지지물과 건물 등에 복합적인 반복하중을 가하여 관련 지지물 및 구조물에 열화현상을 발생시켜 발전소의 안전운전에 심각한 영향을 초래할 가능성을 항상 내포하고 있다. 그럼에도 불구하고 배관진동 대책은 대부분 지지물을 추가로 설치하여 진동준위만 낮추고 있는 실정이다. 따라서 구체적인 배관진동의 예측, 측정 및 평가, 감쇠방안에 이르는 종합적이고 체계적인 연구가 요구되고 있다. 본 연구에서는 지지물의 열화현상 및 부분적인 파손으로 진동준위가 높아진 것으로 추정되는 원자력발전소 주증기관의 진동특성 및 요인을 분석하여 진동감쇠 방안을 도출하고 검증함으로써 배관 및 주변 구조물의 건전성을 확보하고 설비의 신뢰성을 확보하고자 하였다. 이를 위하여 주증기관을 모델링하여 해석하였으며, 발전소의 기동 및 정상운전시의 진동준위를 측정하였다. 또한 발전소의 정진기간중 일부 배관계에 대한 실험적 모우드 해석을 수행하였다. 여러가지 진동감쇠 방안을 검토하여 탄성지지 및 에너지 흡수효과를 동시에 발휘할 수 있는 특수 지지물(WEAR$_{TM}$)을 설치하는 방안을 도출하였으며, 현장에 설치한 후 배관의 진동상태를 확인함으로서 효과적인 방안임을 검증하였다.

• Journal of the Korean Institute of Gas
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• v.2 no.1
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• pp.40-46
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• 1998

Mathematical modeling on the corrosion of the steel casing and main pipe due to the protection current resulting from a cathodic protection system was carried out using boundary element method. The model is consisted of Laplace's equation with non-linear boundary conditions(Tafel equations) and the iterative technique to determine the miexed potential of the steel casing. The model is applied to the normal steel casing section as well as abnormal one with defects such as metal touch and insulation defects. From the modeling procedure, we can calculate the potential distributions and current density distributions of the system. The theoretical results of the qualitatiive corrosion aspect along the steel casing and main pipe agree well with the experimental results within the experimental conditions studied.