• 한국가스학회:학술대회논문집
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• 한국가스학회 2003년도 추계학술발표회 논문집
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• pp.107-113
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• 2003

• 한국가스학회:학술대회논문집
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• 한국가스학회 2005년도 추계학술발표회 논문집
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• pp.5-11
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• 2005

• 비파괴검사학회지
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• 제35권1호
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• pp.31-38
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• 2015

스마트 워터 그리드와 같은 지하매설 상수도 배관망을 구성할 때 누수 지점에 대한 지능적 탐지는 중요한 요소이다. 이런 지능형 배관망의 구성에는 많은 수의 누수탐지센서를 일정한 간격으로 설치하는 것이 필요하며 이들 센서에서 계측되는 신호를 분석해서 누수 유무 및 누수발생시 그 지점의 추정을 신속히 할 수 있어야 한다. 그래서 본 연구에서는 특히 두 지점에서 동시에 누수가 발생하는 경우에 대해 그 센서가 측정한 신호가 가지는 특성 및 두 누수지점 동시 추정 가능성을 심도있게 분석하였다. 즉, 센서간 거리가 315.6 m 인 100A 사이즈의 주철관 상수도 배관에 대해 두 지점 동시 누수시 각각의 개별 센서신호를 계측하였으며, 그 신호를 기반으로 주파수 특성 및 상호상관함수 등의 분석을 통해 두 지점의 누수탐지에 대해 기술하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권3호
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• pp.1086-1103
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• 2020

The automatic identification and classification of image-based weld defects is a difficult task due to the complex texture of the X-ray images of the weld defect. Several depth learning methods for automatically identifying welds were proposed and tested. In this work, four different depth convolutional neural networks were evaluated and compared on the 1631 image set. The concavity, undercut, bar defects, circular defects, unfused defects and incomplete penetration in the weld image 6 different types of defects are classified. Another contribution of this paper is to train a CNN model "RayNet" for the dataset from scratch. In the experiment part, the parameters of convolution operation are compared and analyzed, in which the experimental part performs a comparative analysis of various parameters in the convolution operation, compares the size of the input image, gives the classification results for each defect, and finally shows the partial feature map during feature extraction with the classification accuracy reaching 96.5%, which is 6.6% higher than the classification accuracy of other existing fine-tuned models, and even improves the classification accuracy compared with the traditional image processing methods, and also proves that the model trained from scratch also has a good performance on small-scale data sets. Our proposed method can assist the evaluators in classifying pipeline welding defects.

• 한국물환경학회지
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• 제23권1호
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• pp.103-110
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• 2007

An efficient operational strategy using expert system for metro water supply systems in case of emergency situations is developed in this study. The emergency situations of the water supply systems are classified into three categories : pipeline system accident, machinery and electric facility accident and water quality accident. A PC-based expert system is developed using CLIPS for Seoul metro water supply system, Phase 1 & 2 system and Phase 3 & 4 system. Broad professional knowledges and experiences from the experts in the water supply systems have been collected systematically to construct the knowledge base. Decision-making in case of an emergency is based upon the professional knowledge so that a rational and efficient operational management can be available even in the absence of experienced expert. Especially the expert model developed in this study also provides a guide for pumping operation in case of pipeline accident to confirm that the proper pressure to all nodes in the system is supplied. The pipe network simulator KYPIPE has been consecutively executed by trial and error fashion for each pipeline in the system. The results from KYPIPE were included in the knowledge base to supplement the knowledge of the field engineers.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권5호
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• pp.2433-2452
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• 2017

Recently, the pipeline-forwarding has been proposed as a new technique to resolve the end-to-end latency problem of the duty-cycle MAC protocols in Wireless Sensor Networks (WSNs). Some protocols based on this technique such as PMAC and PRI-MAC have shown an improvement not only in terms of reducing end-to-end latency but also in terms of reducing power consumption. In these protocols, however, the sensor nodes still waste a significant amount of energy for unnecessary idle listening during contention period of upstream nodes to check the channel activity. This paper proposes a new pipeline-forwarding duty-cycle MAC protocol, named RP-MAC (Reduced Pipelined duty-cycle MAC), which tries to reduce the waste of energy. By taking advantage of ACK mechanism and shortening the handshaking procedure, RP-MAC minimizes the time for checking the channel and therefore reduces the energy consumption due to unnecessary idle listening. When comparing RP-MAC with the existing solution PRI-MAC and RMAC, our QualNet-based simulation results show a significant improvement in term of energy consumption.

• 한국안전학회지
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• 제39권1호
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• pp.27-32
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• 2024

This study analyzed cases of hydrogen (H₂) and natural gas (CH₄) leakage from a hydrogen-blended natural gas pipeline to determine a range of leakage characteristics, including leakage type, pipe material, pipe diameter, pressure, and damage size. Based on the results of this analysis, five hydrogen-blended natural gas leakage scenarios were selected. The national vision for a carbon-neutral society by 2050 is a very important strategic objective and promotes environmentally sustainable economic development in the age of the climate crisis. Accordingly, zero-carbon and low-carbon policies are being promoted in various fields, including energy production, consumption, and industrial processes. Hydrogen-blended natural gas is eco-friendly and is considered an important step towards carbon neutrality, with various countries including the United States and several European countries conducting empirical research to further investigate its potential. In Korea, a national research project commenced in April 2023 to verify and demonstrate the life cycle safety of blending hydrogen into the natural gas network. The results of this study will provide important data for the analysis of the damage impacts caused by the leakage of hydrogen-blended natural gas, such as the diffusion of gas clouds, fires, and gas explosions.

• 에너지공학
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• 제17권3호
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• pp.139-144
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• 2008

최근 유가의 고공행진 때문에 한국은 해외 에너지 자원개발뿐만 아니라 에너지 소비를 줄이기 위한 국가적 정책으로 기존 설비의 에너지 효율을 증가시키는 방안을 모색하는 것이 필요한 시점이다. 따라서 본 연구는 이런 국가적 사안에 부합하고자 인천생산기지 고압 LNG 배관망에 대하여 수정유량방정식을 사용한 Newton Method로 접근하였고, 유창조절밸브(FCV)에 의해 지배적인 영향을 받는 것을 확인할 수 있었다. 또한, 고압펌프는 유량조절밸브 50%의 개도율에서 최고효율을 보여 주었고, 고압배관망 내에서 배관저항곡선은 LNG 헤드가 1,500m 이상이 되어야만 토출이 가능한 것을 보였다. 고압펌프의 운전점으로부터 운전비용을 산출하였고, 최고 효율시 운전비용과 비교하여 운전비용을 절감할 수 있는 금액을 산출하였다. 특히 일간 시간대별 운전비용 절감액뿐만 아니라 연간 일별 운전비용 절감액을 산출하였으며, 그 결과 고압배관망은 연간 138백만원을 절감할 수 있다. 이것은 연간 고압펌프 1기당 9,823천원을 절감할 수 있다는 것을 의미한다. 결론적으로 본 연구는 복잡한 고압 LNG 배관망에서 고압펌프의 운전특성과 운전비용 절감효과를 확인할 수 있었다. 또한 이것은 미시적으로 생산기지의 효율적 미래운영에 대한 기여와 더불어 거시적으로 국가 에너지 경쟁력 제고에 기여할 수 있을 것이다.

• 상하수도학회지
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• 제34권2호
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• pp.139-147
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• 2020

This paper suggests a nonlinear pressure consideration scheme through an unsteady pipe network analyzer for leakage detection with a portable pressure wave generator. In order to evaluate the performance of a proposal scheme, linear input pattern has been simulated and experiments had been carried out under both no leakage and one leakage conditions in a reservoir-pipeline-valve system. This method using portable pressure wave generator showed that a leakage can be detected from a reflection where a leakage is originated through time domain analysis. Meaningful similarity in pressure response between nonlinear input pattern and experimental results were found both no leakage and a leakage conditions.

• 한국가스학회지
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• 제15권1호
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• pp.54-59
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• 2011

일반적으로 유동헌팅현상은 대부분의 오리피스 유량계에서 관찰되나 유동헌팅의 크기는 각 계량 시스템에 따라 다르다. 이에, 실제 배관계통에서 배관경과 유동의 불안정성, 유동헌팅율간의 영향을 조사하고자 유량계 관경과 유량계 전후단 배관의 직경을 변경하면서 이에 따른 유동의 특성 변화와 헌팅율과의 관계에 대하여 1차원 배관망해석 모델을 구축하고 해석을 수행하였다. 결과적으로, 유량계 배관경과 전후단 배관경의 변화에 따른 차압변화량과 유동헌팅율의 영향을 분석하고 그 상관관계를 규명하였다.