• 환경위생공학
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• 제14권4호
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• pp.137-142
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• 1999

Current semiconductor industry factories are relying on the end-of-pipe treatment technology for waste water treatment and thus they mostly suffer from severe industrial water shortage. As a result in order to solve those waste and industrial water problems, there requires to be changed to the Clean Technology, that is Pollution Prevention Technology. Through above strategic actions with the Clean Technology, we shall strength more powerful and logical environmental pollution prevention system than those in the past. By changing the end-of-pipe treatment technology for waste water treatment and thus they mostly suffer from severe industrial water problems, there requires to be changed to the Clean Technology, that is Pollution Prevention Technology. Through above strategic actions with the Clean Technology, we shall strength more powerful and logical environmental pollution prevention system than those in the past. By changing the end-of-pipe treatment technology with physical, chemical and biological treatment methods as a mixed stream basis for treating of semiconductor waste stream into clean technology with pollution prevention technology as a waste segregation basis, we can bet 20 to 30% investment reduction as compared with end-of-pipe treatment technology.The results for water quality analysis were as follows : 1. Water quality analysis of the before treatment : pH : 9~10.5, Conductivity : $300~7,000{\mu}s/cm$, TDS : more then $3,000mg/{\ell}$, COD : $200~250mg/{\ell}$, SS : $500~600mg/{\ell}$, n-H : $8.3mg/{\ell}$ 2. Water quality analysis of the after treatment : pH : 6.5~7.5, Conductivity : 0.059, TDS : $40{\mu}s/cm$, COD : $20mg/{\ell}$, SS : $5mg/{\ell}$ n-H : $0.6mg/{\ell}$

• Earthquakes and Structures
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• 제22권4호
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• pp.431-437
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• 2022

One of the best choice for transportation of oil and gas at the end of rivers or seas is concrete pipelines. In this article, a concrete pipe at the end of river is assumed under the earthquake load. The Classic shell theory is applied for the modelling and the corresponding motion equations are derived by energy method. An external force induced by fluid around the pipe is asssumed in the final motion equations. For the solution of motion equations, the differential quadrature method (DQM) and Newmark method are applied for deriving the dynamic deflection of the pipe. The effects of various parameters including boundary conditions, fluid and length to thickness ratio are presented on the seismic response of the concrete pipe. The outcomes show that the clamped pipe has lower dynamic deflection with respect to simply pipe. In addition, with the effect of fluid, the dynamic defelction is increased significantly.

• Earthquakes and Structures
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• 제22권5호
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• pp.439-445
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• 2022

One of the best choice for transportation of oil and gas at the end of rivers or seas is concrete pipelines. In this article, a concrete pipe at the end of river is assumed under the earthquake load. The Classic shell theory is applied for the modelling and the corresponding motion equations are derived by energy method. An external force induced by fluid around the pipe is asssumed in the final motion equations. For the solution of motion equations, the differential quadrature method (DQM) and Newmark method are applied for deriving the dynamic deflection of the pipe. The effects of various parameters including boundary conditions, fluid and length to thickness ratio are presented on the seismic response of the concrete pipe. The outcomes show that the clamped pipe has lower dynamic deflection with respect to simply pipe. In addition, with the effect of fluid, the dynamic defelction is increased significantly.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.353-354
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• 2006

The automatic inspection system is developed for the formed end part of automotive fuel pipe. The developed system has functions of outer diameter and formed end length measurement by LVDT(linear variable differential transformer) together with burr cleaning of automotive fuel pipe. The measured data are managed and controlled in real time by embedded SPC(statistical process control) program. The system is composed of mechanical part, electronic part and developed software system. These three parts operate automatically by mutual communication with each other. The developed system showed good results in finding inferior goods and efficiency improvement of the fuel pipe production line. It also eliminated the unreliable manual inspection processes and improved the confidence of product quality.

• Corrosion Science and Technology
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• 제19권4호
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• pp.189-195
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• 2020

Two air vents situated on a heat transport pipe in district heating system were exposed to the same environment for 10 years. However, one air vent was more corroded than the other. It also had a hole on the top of the front-end pipe. Comparative analysis was performed for these air vents to identify the cause of corrosion and establish countermeasures. Through experimental observation of the damaged part and analyses of powders sampled from air vents, it was found that corrosion was initiated at the top of the front-end pipe. It then spread to the bottom. Energy dispersive X-ray spectroscopy results showed that potassium and chlorine were measured from the corroded product in the damaged air vent derived from rainwater and insulation, respectively. The temperature of the damaged air vent was maintained at 75 ~ 120 ℃ by heating water. Rainwater-soaked insulation around the front-end pipe had been hydrolyzed. Therefore, the damaged air vent was exposed to an environment in which corrosion under insulation could be facilitated. In addition, ion chromatography and inductively coupled plasma measurements indicated that the matrix of the damaged front-end pipe contained a higher manganese content which might have promoted corrosion under insulation.

• 한국지반환경공학회 논문집
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• 제17권12호
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• pp.65-72
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• 2016

There are numerous factors that affect stress distribution in a buried pipe, such as the shape, size, and stiffness of the pipe, its burial depth, and the stiffness of the surrounding soil. In addition, the pipe can benefit from the soil arching effect to some extent, through which the overburden and surcharge pressure at the crown can be carried by the adjacent soil. As a result, the buried pipe needs to support only a portion of the load that is not transferred to the adjacent soil. This paper presents numerical efforts to investigate the stress distribution in the buried concrete pipe under various environmental conditions. To that end, a nonlinear elasto-plastic model for backfill materials was implemented into finite element software by a user-defined subroutine (user material, or UMAT) to more precisely analyze the soil behavior surrounding a buried concrete pipe subjected to surface loading. In addition, three different backfill materials with a native soil were selected to examine the material-specific stress distribution in pipe. The environmental conditions considering in this study the loading effect and void effects were investigated using finite element method. The simulation results provide information on how the pressures are redistributed, and how the buried concrete pipe behaves under various environmental conditions.

• Nuclear Engineering and Technology
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• 제49권7호
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• pp.1463-1471
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• 2017

In order to monitor the pipe thinning caused by flow-accelerated corrosion (FAC) that occurs in coolant piping systems, a shear horizontal ultrasonic pitch-catch waveguide technique was developed for accurate pipe wall thickness monitoring. A clamping device for dry coupling contact between the end of the waveguide and pipe surface was designed and fabricated. A computer program for multi-channel on-line monitoring of the pipe thickness at high temperature was also developed. Both a four-channel buffer rod pulse-echo type and a shear horizontal ultrasonic waveguide type for high-temperature thickness monitoring system were successfully installed to the test section of the FAC proof test facility. The overall measurement error can be estimated as ${\pm}10{\mu}m$ during a cycle from room temperature to $200^{\circ}C$.

• 한국산업융합학회 논문집
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• 제24권5호
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• pp.617-623
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• 2021

The objective of this study is to simulate valve flow coefficient and flow characteristics such as velocity and pressure distribution for butterfly valve. The size of the valve used in this study is 125A. The range of the valve opening angle was α=15°~70°, and it was changed by 5°. At the range of α=15°~30°, the valve flow coefficient K_𝜐 gradually increased, and after α=30°, it increased rapidly. In the range of α=20°~70°, the pressure change in the -2.9cm~+2.9cm region in the pipe greatly depended on the opening angle and the position within the pipe. However, after +2.9cm, the pressure at the rear end of the valve was shown to depend only on the opening angle. At α=20°, Vortex shedding occurred for the first time at time t=0.25sec and continuously occurred in rear end of the valve over time. After α=45°, in the flow pattern at the rear end of the valve, the upward flow at the lower end of the valve and the flow at the upper end met each other to form a mixed flow. This flow phenomenon was shown to form a more intense mixed flow in the rear end region as the opening angle increased. Vortex flow occurred for the first time at α=15°, and the opening angle increased, the occurrence and disappearance of this flow phenomenon occurred periodically according to the certain flow region. The pattern of the pressure distribution in the region at the rear end of the valve showed a tendency to agree well with the results of the vorticity distribution.

• Corrosion Science and Technology
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• 제7권5호
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• pp.265-268
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• 2008

Prestressed Concrete Cylinder Pipe(PCCP) had became one of the dominating kinds of pipes substituting for steel pipes because of its unique feature (high intensity, high pressure and high leakproofness). PCCP was produced firstly by Bonna company in France. By the end of 20th century, there were over 19000 km of this product installed in America. PCCP was introduced from Ameron company by Shandong Eletric Power Pipeline Engineering Company in 1988. As the statistical data in 2002, 700 km of PCCP had been applied in China, and the application trended towards rapid increase.Since prestressing wire would be corroded in environment, Several accidents due to the breakdown of pipe had happened. Consequently the external wall of pipe should be covered with protective coatings. There was a lack of technical study in corrosion and control of PCCP, because PCCP had been applied for a short time in China. in order to ensure the service life of PCCP, we have developed a kind of protective coating for concrete pipe, which had high intensity and anti-corrosive property with convenient applicability. The physical and chemical properties, painting technology and field application of this coating was introduced in the paper, at the same time, the future of external protective coating for PCCP was looked into.

• 한국환경과학회지
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• 제8권1호
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• pp.45-50
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• 1999

깨끗한 모래로 채워진 4개의 16갤론 크기 드럼통에 주물 파이프가 설치되었고 각 파이프에는 3개의 styrene butadiene rubber gasket(1개의 joint와 2개의 end caps)을 장치하였다. 각 파이프는 상수로 채워 내부의 압력을 약 40psi로 유지하였다. 첫 번째 드럼은 일정량의 휘발유로, 두 번째 드럼은 pyrene과 naphthalene을 포함한 휘발유로, 세 번째 드럼은 toluene으로 채워졌고, 네 번째 드럼은 대조군으로 사용되었다. 외부 오염물질의 이동에 의한 오염을 조사하기 위해 일정 간격으로 파이프 내의 물을 약 2년 간 조사하였다. 오염 물질이 투입된 3개의 드럼에서 약 100일 후부터 유기 오염 물질이 검출되었고 외부에 채워진 유기물이 고갈될 때까지 계속적으로 증가하는 추세를 보였다. 이미 오염된 물을 깨끗한 물로 청소한 후에도 오염된 gasket에 남아있는 유기물질이 유출되어 파이프 내의 물이 쉽게 오염되었으며 약 10일 후에는 청소 이전의 농도로 검출되어 gasket에 의한 오염이 오래 동안 지속되는 것으로 나타났다.