• 플랜트 저널
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• 제7권1호
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• pp.56-63
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• 2011

The identifying cause of leakage problems on mechanical seal in a feed water pump of power plant have been difficult because of technical limits of domestic mechanical seal manufacturer and the various conditions of power plants. This paper can get a conclusion through the consideration study and experiment test of mechanical seal characteristics of feed water pump depending on oxygen treatment as follows. The oxygen treatment increase dissolved oxygen and cause a corrosion on the mechanical seal stationary ring composed of antimony as well as leakage problems. For solving leakage problems of seal, to eliminate dissolved oxygen in the cooling water of seal with hydrazine injection can prevent leakage problems of mechanical seal in feed water pump.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2001년도 춘계학술대회 논문집
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• pp.197-201
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• 2001

Measuring of the dissolved oxygen is widely used for the environmental control of natural waters, sewage waste treatment, medical and biochemical studies, soil husbandry, food and drug process control, and prevention of corrosion in boilers. Especially, a power plants need special management for preventing accidents from corrosion, therefore, it is essential to measure the concentration of dissolved oxygen in real-time. In this paper we present a method of measuring dissolved oxygen very accurately up to ppb units. This method, called polarographic method, is based on the measures of the electric current generated by the oxidation process in cathode and de-oxidation process in anode, assuming that the amount of the current is proportional to the density of dissolved oxygen.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 학술회의 논문집 정보 및 제어부문 B
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• pp.731-734
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• 2003

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, amplitude of stray current, point of source of stray current and so. In this paper, results of development about data logger apparatus for measurement stray current of subway and power line are presented.

• Structural Monitoring and Maintenance
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• 제5권2호
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• pp.313-323
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• 2018

The presence of water inside concrete structures is an essential condition for the deterioration of the structures. The free water in the concrete pores and micro-cracks is the culprit for the durability related problems, such as alkali-aggregate reaction, carbonation, freeze-thaw damage, and corrosion of steel reinforcement. To ensure the integrity and safe operation of the concrete structures, it is very important to monitor water seepage inside the concrete. This paper presents the experimental investigation of water seepage monitoring in a concrete slab using piezoelectric-based smart aggregates. In the experimental setup, an $800mm{\times}800mm{\times}100mm$ concrete slab was fabricated with 15 SAs distributed inside the slab. The water seepage process was monitored through interrogating the SA pairs. In each SA pair, one SA was used as actuator to emit harmonic sine wave, and the other was used as sensor to receive the transmitted stress wave. The amplitudes of the received signals were able to indicate the water seepage process inside the concrete slab.

• 한국주조공학회지
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• 제24권4호
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• pp.209-216
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• 2004

High silicon cast irons(HSCI) with the high acid resistance have been used for the prevention of acid corrosion occurring in various structures under acid conditions. However, the HSCI is only known as one of materials which have high acid resistance, but few work has dealt with this material in domestic. Therefore, in this study, the acid resistance of various cast irons with alloying elements and melting conditions have been examined, and studied the influences of the matrix structures, mechanical properties and morphologies of graphite. The results obtained in this study are as follows : In case of melting temperature, the mechanical properties of specimen manufactured with high temperature of $1650^{\circ}C$ showed higher value because the inclusion and impurity were removed. In case of pouring temperature, the mechanical properties of specimen fabricated below $1350^{\circ}C$ of pouring temperature showed higher value because the amount of gas absorption from atmosphere decreased during the solidification time. The corrosion rate decreased with increase in Si content. On the other hand, Mn addition appeared an opposite trend with Si.

• 한국방재학회 논문집
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• 제8권6호
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• pp.47-52
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• 2008

겨울철 도로의 결빙을 방지하기 위하여 염화물계 제설제가 많이 사용되고 있으며, 매년 사용량이 증가하고 있다. 이러한 제설제의 사용은 구조물의 부착강도 저하, 표면스케일링, 환경오염을 발생시킨다. 본 연구에서는 17년간 사용해 온 콘크리트 도로 시설물의 피해상황에 대하여 현장조사를 실시하였으며, 기존 제설제와 개발된 친환경 제설제의 부식 저항성에 대한 비교 실내실험을 수행하였다. 현장피해 조사결과에 따르면, 제한 염화물량의 침투 깊이는 평균 40 mm정도로 나타났고, 조사구간의 표면 염화물 농도는 $3.45kg/m^3$으로 조사되었으며, 이에 비해 탄산화 깊이는 매우 적었다. 한편, 친환경 제설제의 경우, 기존 염화물계 제설제에 비해 염화물 침투 깊이가 적었으며, 부식저항성도 높은 것으로 나타났다.

• 한국화재소방학회논문지
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• 제27권5호
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• pp.26-31
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• 2013

원전의 가압기 지지대에 사용되는 볼트는 설계 시 안전율 측면에서 충분한 경도의 볼트를 사용하지만, 현장실사를 통해 허용 경도 범위를 초과하는 볼트가 일부 확인되었다. 이러한 높은 경도의 볼트는 응력부식 및 재료의 파괴인성이 취약하고, 가압기는 부식에 취약한 환경이므로 이 부분에 대한 검토가 필요하다. 따라서 본 연구에서는 현장실사를 통해 원전 가압기 지지대에 사용되는 볼트의 경도를 측정하였고, 이를 통해 응력부식과 부재의 파괴인성에 의한 균열을 제한할 수 있는 최대 허용응력을 계산하였다. 또한 정상운전 및 사고운전 시 발생할 수 있는 지지대 볼트의 응력을 수치해석 프로그램인 ANSYS를 사용하여 예측하였고, 이 응력이 응력부식을 제한할 수 있는 최대 허용응력 내에 있는 지 검토하였다. 검토 결과 정상 및 사고운전 조건에서 볼트의 응력은 응력부식에 대해 허용응력 안전 기준치를 만족하는 것으로 나타났다. 그러나 향후 가압기 지지대의 구조물 체결방법을 체결 절차에 반영하여 정비 시 가압기의 건전성을 확보할 수 있도록 검토가 필요하다.

• Smart Structures and Systems
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• 제6권3호
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• pp.277-290
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• 2010

Internationally the load carrying capacity of bridges is decreasing due to material deterioration while at the same time increasing live loads mean that they are often exposed to stresses for which they were not designed. However there are limited resources available to ensure that these bridges are fit for purpose, meaning that new approaches to bridge maintenance are required that optimize both their service lives as well as maintenance costs. Wireless sensor networks (WSNs) provide a tool that could support such an optimized maintenance program. In many situations WSNs have advantages over conventional wired monitoring systems in terms of installation time and cost. In order to evaluate the potential of these systems two WSNs were installed starting in July 2007 on the Humber Bridge and on a nearby approach bridge. As part of a corrosion prevention strategy, a relative humidity and temperature monitoring system was installed in the north anchorage chambers of the main suspension bridge where the main cables of the bridge are anchored into the foundation. This system allows the Bridgemaster to check whether the maximum relative humidity threshold, above which corrosion of the steel wires might occur, is not crossed. A second WSN which monitors aspects of deterioration on a reinforced concrete bridge located on the approach to the main suspension bridge was also installed. Though both systems have provided useful data to the owners, there are still challenges that must be overcome in terms of monitoring corrosion of steel, measuring live loading and data management before WSNs can become an effective tool for bridge managers.

• 상하수도학회지
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• 제37권4호
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• pp.203-214
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• 2023

In this study, the physical properties and fracture characteristics according to the tensile load are evaluated on the materials of the polymeric filler and carbon fiber-based composite sleeve technique. The polymeric filler and the composite sleeve technique are applied to areas where the pipe body thickness is reduced due to corrosion in large-diameter water pipes. First, the tensile strength of the polymeric filler was 161.48~240.43 kg_f/cm², and the tensile strength of the polyurea polymeric filler was relatively higher than that of the epoxy. However, the tensile strength of the polymeric filler is relatively very low compared to ductile cast iron pipes(4,300 kg_f/cm²<) or steel pipes(4,100 kg_f/cm²). Second, the tensile strength of glass fiber, which is mainly used in composite sleeves, is 3,887.0 kg_f/cm², and that of carbon fiber is up to 5,922.5 kg_f/cm². The tensile strengths of glass and carbon fiber are higher than ductile cast iron pipe or steel pipe. Third, when reinforcing the hemispherical simulated corrosion shape of the ductile cast iron pipe and the steel pipe with a polymeric filler, there was an effect of increasing the ultimate tensile load by 1.04 to 1.06 times, but the ultimate load was 37.7 to 53.7% compared to the ductile cast iron or steel specimen without corrosion damage. It was found that the effect on the reinforcement of the corrosion damaged part was insignificant. Fourth, the composite sleeve using carbon fiber showed an ultimate load of 1.10(0.61T, 1,821.0 kg_f) and 1.02(0.60T, 2,290.7 kg_f) times higher than the ductile cast iron pipe(1,657.83 kg_f) and steel pipe(2,236.8 kg_f), respectively. When using a composite sleeve such as fiber, the corrosion damage part of large-diameter water pipes can be reinforced with same level as the original pipe, and the supply stability can be secured through accident prevention.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1996년도 제23회 학술대회
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• pp.47-52
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• 1996

본 연구에서는 각종 강구조물의 도장전 샌드블리스트 작업에 다른 공해를 방지하기 위해, 모래-물의 2상류를 분사할 수 있는 샌드블라스트 장치를 제작하여, 2상류 분사에 따른 마멸-부식(wear-corrosion)특성과 slurry erosion에 의한 anchor pattern 및 침식-마멸거동을 고찰하고, 물에 의한 강구조물의 부식방지를 위한 부식억제제가 강구조물의 도막에 미치는 방식특성을 구명함으로써 공해방지, 부식손상 및 산업의 국제경쟁력 향상에 기여하고자 한다.