• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 B
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• pp.1376-1378
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• 2004

When an underground pipeline runs parallel with DC traction systems, it suffers from DC traction interference. Because the train is fed by the substation through the overhead wire and return current back to the substation via the rails. If these return rails are poorly insulated from earth, DC current leak into the earth and can be picked up by nearby pipeline. It may bring about large-scale accidents even in cathodically protected systems. In this paper we analyze the cathodic protection systems of buried pipelines and DC traction stray current influence on it using the simulation software CatPro. We can discuss the problems and mitigation of DC traction interference for protected pipeline.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.220-222
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• 2007

With the wide spread of direct current (DC) electric railroads in Korea, the stray currents or leakage currents from negative return rails become a pending problem to the safety of nearby underground infrastructures. The most widely used mitigation method for this interference is the stray current drainage method, which connects the underground metallic structures to the rails with diodes (polarized drainage) or thyristor (forced drainage). Although this method inherently possesses some drawbacks, its cost effectiveness and efficiency to protect the interfered structures has been the main reason for the wide adoption. In this paper, we show the field test results for the application of stray current drainage system to a city gas pipeline paralleling a depot area of a metropolitan rapid transit system. The process for optimal positioning is briefly illustrated. The effectiveness of constant voltage, constant current, and constant potential drainage schemes was also described.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 D
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• pp.2729-2731
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• 2005

In present, most of metallic structures(gas pipeline, oil pipeline, water pipeline, etc) are running parallel with subway and power line in seoul. Moreover subway system and power line make a stray current due to electrical corrosion on metallic structures. The owner of metallic structures has a burden of responsibility for the protection of corrosion and the prevention against big accident such as gas explosion or soil pollution and so on. So, they have to measure and analyze the data about P/S(Pipe to Soil) potential due to stray current of subway system. In this paper, results of development about Real-time Wireless Remote Monitoring System for Stray Current of Subway System are presented.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 D
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• pp.2732-2734
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• 2005

In present, most of metallic structures(gas pipeline, oil pipeline, water pipeline, etc) are running parallel with subway and power line in seoul. Moreover subway system and power line make a stray current due to electrical corrosion on metallic structures. The owner of metallic structures has a burden of responsibility for the protection of corrosion and the prevention against big accident such as gas explosion or soil pollution and so on. So, they have to measure and analyze the data about P/S(Pipe to Soil) potential due to stray current of subway system. So, we have developed the Real-time Wireless Remote Monitoring System for Stray Current of Subway System. In this system, the permanent buried type reference electrode is necessary. In this paper, results of development about the permanent buried type reference electrode($Cu/CuSO_4$) are presented.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.273-275
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• 2005

The national need to establish a new stray current mitigation method to protect the underground metallic infrastructures in congested downtown area forced us to design and develop the distributed impressed current cathodic protection (DICCP) system. The main purpose of this system is to replace the stray current drainage bond methods, which is widely adopted by pipeline owners in Korea. Currently, forced drainage makes up about 85% of total drainage facilities installed in Korea because polarized drainage can neither drain perfectly the stray currents during normal operation of electric vehicle nor drain the reverse current during regenerative braking at all. The forced drainage, however, has been abused as an alternative cathodic protection system, which impresses currents from rails to the pipelines and accordingly uses the rails as anodes. As a result, it is necessary to consider a new method to both cathodically protect the pipelines and effectively drain the stray currents. In this paper, we describe the design parameters and installation schemes of DICCP system that can meet these demands.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 추계학술대회 논문집 전력기술부문
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• pp.382-384
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• 2003

In case of parallel running with underground gas pipeline and subway, stray current of subway makes a interference on gas pipeline. This interference is one of the reason of gas pipeline corrosion. So, the high speed response rectifier was developed in order to mitigate a interference. In this paper, the field test result of proposed rectifier is presented. The effect of an alternative in stead of the forced drainage system is also presented.

• Current Optics and Photonics
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• 제5권3호
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• pp.220-228
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• 2021

To improve the measurement accuracy of a solar-radiation observer instrument, aiming at the problem of multiorder-stray-light interference caused by the diffraction of the flat-field concave grating in the spectroscopic system, straylight suppression methods for different forms of optical traps are studied. According to the grating surface-scattering distribution-function model, the bidirectional scattering distribution function (BSDF) of a dust-polluted surface and the flat-field concave grating's transition area of the spectroscopic system is calculated, and a Lyot stop with blade baffle is designed to suppress this kind of stray light. For diffraction multiorder stray light, based on the theory of light-energy transmission, a design for precise positioning of the trench optical trap is proposed. The superiority of the method is verified through simulation and actual measurement. The simulation results show that in a spectroscopic system approximately 160 mm × 140 mm × 80 mm in size, the energy of the stray light is reduced by one order of magnitude by means of the trench optical trap and Lyot stop, and the number of beams is reduced from 5664 to 1040. The actual measurements show that the stray-light-suppression efficiency is about 69.4%, which is effective reduction of the amount of stray light.

• 한국가스학회지
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• 제12권1호
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• pp.19-24
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• 2008

산업화, 도시화에 따라 관리 주체가 다른 지중 금속시설물들이 크게 늘고 있으며 이러한 시설물의 보호를 위한 전기방식법, 특히 외부전원법의 적용이 전기방식에 대한 인식의 확산과 더불어 크게 증가하고 있다. 그러나 시스템의 설치를 위한 공간 확보의 어려움과 더불어 시설물 상호간의 표류전류 간섭 문제가 개별 관리주체로서는 해결할 수 없는 현안이 되고 있다. 이에 본 논문에서는 개별적으로 적용되던 전기방식 시스템 상호간의 간섭 사례를 현장 진단을 통하여 예시하고 이에 대한 대책으로 공용양극 외부전원 시스템을 설계, 현장 실증을 통하여 하나의 대안으로 제시하였다.

• Corrosion Science and Technology
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• 제19권4호
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• pp.211-223
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• 2020

The external corrosion of buried piping can be controlled using both coating and cathodic protection. Several factors are involved in the damage and deterioration of the coating on pipes. There are many detection methods for coating defects on pipes and the direct current voltage gradient (DCVG) method is one of the most powerful methods. However, the detection reliability of DCVG can be affected by interferences such as stray current, metal objects connected to rectifiers, and copper grids. Therefore, this study focused on the interference effects of rectifiers and a copper grid on the reliability of coating flaw detection. As the length of the interference pipe connected to the rectifier increased, the reliability decreased. In contrast, as the distance between the pipe and the copper grid increased, the reliability of the coating flaw detection increased. The detection results produced by the DCVG method were discussed using current and potential simulations for a pipe with a rectifier and copper grid interference in the soil.

• 한국산업융합학회 논문집
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• 제23권5호
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• pp.757-763
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• 2020

City gas buried pipes are managed by corrosion protection to prevent corrosion. In the case of the press-in section, the double pipe and the main pipe may cause corrosion under the influence of stray current, which can shorten the life of the pipes. In addition, if the insulator is filled in the press-in section, the press-in section itself is a single structure, and can be directly affected by external impact, and when the surrounding ground subsidence occurs, the stress may be concentrated, resulting in serious consequences. In this study, a serration-type shock absorber in the form of a sliding support was proposed as a new buried double piping construction method using EPS. The serration-type shock absorber can contribute to the improvement of the integrity of the buried double piping, as it can utilize the gas piping's own ductility and stress distribution characteristics with proper anti-corrosion management and shock-absorbing material properties by preventing contact inside the buried double pipe. However, for application to ground piping, there remains a task to supplement the vulnerability against fire due to the characteristics of EPS materials.