• 소음진동
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• 제8권1호
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• pp.49-56
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• 1998

Although the fundamental resonance frequency of a Helmholts resonator is mainly determined by the volume of the resonator and the size of the hole, it is also affected by the position of the hole and the shape of the resonator. In this study, the inertial end corrections and the fundamental resonance frequencies of concentric pipe resonators are estimated for various positions of the hole and shapes of the resonator by using the 3-D analysis. For an effective noise reduction in concentric pipe resonators with several holes, an optimal spatial hole-distribution is proposed based on the calculated transmission loss for various hole-distributions and sizes of holes.

• 상하수도학회지
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• 제21권6호
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• pp.717-726
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• 2007

Fully-grown flocs in a mixing tank of membrane filtration with dead-end membrane are ruptured while passing through a pump and the ruptured flocs are aggregated again in a Membrane-Feed-Pipe (MFP). To look at more details, this study tries to relate the reaggregation to a parameter of mixing intensity in MFP, i.e., G-value. The G-value is a function of Reynolds number, pipe diameter, friction factor and average velocity in MFP. To deal with polydispersity condition, we develop a representative particle size called in this study EDPD (Effective Diameter for Polydispersity condition in Dead-end filtration). The experimental results show that as the G-value increases, the EDPD decreases and also the cake resistance increases. Through comparison between EDPD and cake resistance, these results show that cake resistances are controlled by reaggregation phenomenon in MFP. The effect of detention time in MFP, however, does not affect the reaggregation of the broken flocs as G-values are increased.

• 한국소음진동공학회논문집
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• 제11권9호
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• pp.406-413
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• 2001

The current study depicts and experimental work of the impulsive wave discharged from the exit of several kinds of right-angle bend pipes, which are attached to the open end of a simple shock tube. The weak normal shock wave with Mach number from 1.02 to 1.20 is employed to obtain the impulsive wave propagating outside the exit of the pipe bends. The experimental data of the magnitude of the impulsive wave and its propagation directivity are analyzed to characterize the impulsive waves discharged from the right-angle bend pipes and compared with those from a straight pipe. The impulsive waves are visualized by a Schlieren optical system. A computation work using the two-dimensional, unsteady, compressible Euler equation is also carried out to represent the experimented impulsive waves. The results obtained show that a right-angle miter bend considerably reduces the magnitude of the impulsive wave and its directivity toward to the pipe axis, compared with the straight pipe. It is believed that the right angle miter bend pipe can play a role of passive control agianst the impulsive wave.

• 생물환경조절학회지
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• 제4권1호
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• pp.17-24
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• 1995

본 연구는 파이프하우스의 구조적 안전성을 검토하는데 필요한 기초자료를 구축하기 위하여 실시하였다. 지반에 매입된 파이프의 지점상태를 검토하여 적합한 구조해석 모델을 찾고, 파이프를 말뚝기초로 가정했을 때의 파이프의 지지력 및 인발 저항력을 구하기 위하여 모형 실험을 실시하였으며, 그 결과를 요약하면 다음과 같다. 1. 파이프하우스의 지점상태를 검토해본 결과 단동 하우스에서는 수평 및 연직하중 모두 고정으로, 연동하우스에서는 수평하중 재하시 힌지, 연직 하중 재하시 고정으로 해석하는 것이 실험치에 더 가까운 것으로 나타났다. 2. 지반에 매입된 파이프의 인발저항력은 파이프 직경 및 매입깊이에 따라 논의 연한지반에서는 35-54kg, 밭의 보통지반에서는 61-98kg, 단단한 지반에서는 108-120kg이상으로 나타났으며, 파이프와 흙사이의 주변마찰력은 1.51-4.76t/$m^2$정도의 범위를 보였다. 3. 파이프 직경 및 매입깊이에 따른 기초 지지력은 연한지반의 경우 35-76kg, 보통지반은 88-158kg, 단단한 지반은 131-305kg의 범위를 보였으며, 파이프의 선단지지력은 연한지반 0-22kg, 단단한 지반 22-140kg으로 나타났다. 4. 국내에서 많이 보급되어 있는 대표적인 파이프하우스의 경우, 적설심 30cm 까지는 파이프의 매입깊이가 30cm이면 지지력이 충분하지만 그 이상의 적설심에서는 지반의 종류에 따라 매입깊이를 증가시켜야 하고, 인발저항의 경우도 풍속 30㎧까지는 매입깊이 30cm이면 충분하지만 그 이상의 풍속에 대하여는 매입깊이를 증가시키거나 보강이 필요한 것으로 나타났다.

• 한국시뮬레이션학회논문지
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• 제14권4호
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• pp.69-76
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• 2005

To investigate the characteristics of the sound-pipe on the top of King Song-Dok bell, using computer simulation, the throat impedance was evaluated for the straight pipe and conical pipes with varying taper angles. When sound propagates in a rigid walled, unflanged circular pipe with wavelength larger than radius, the acoustic motion is planar, much as in a bar. The incident sound waves are reflected at the end of pipe and some of them are transmitted. The reflection coefficient and radiation impedance of the sound-pipe of King Song-Dok bell were calculated, and the results demonstrated that the high frequency sound is radiated through the sound-pipe. It behaves like a frequency filter.

• 한국막학회:학술대회논문집
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• 한국막학회 1991년도 추계 총회 및 학술발표회
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• pp.49-50
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• 1991

최근 산업폐수의 수질오염에 대한 국민적 관심이 높아지면서 정부의 배출수 수질기준강화 및 배출부과금의 인상 등으로 기업의 폐수처리에 관한 인식이 상당히 달라졌다. 기존의 폐수처리는 각공정에서 발생되는 폐수는 종합적으로 수집하여 처리하는 소위 END OF PIPE 처리방법이 대부분이며 산화/환원, 응집/침전, 미생물분해, 여과 등이 주로 사용되고 있다. 그러나 END OF PIPE 처리방식에서는 소량이지만 처리가 어렵거나 독성이 강한 물질이 일부분의 공정에서 발생되어도 분리처리되지 않고 전체적으로 합쳐지므로 처리시설이 복잡하고 규모도 커진다. 따라서 최근의 폐수처리는 각 생산공정에서 발생되는 폐수를 소규모의 처리시설로 처리하기 어려운 소량의 오염물질을 제거하거나 유효성분일 경우 회수하여 재활용하는 방향으로 연구가 진행되고 있다.

• 대한기계학회논문집A
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• 제33권7호
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• pp.664-672
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• 2009

Nozzle in nuclear power plant is connected to pipe using safe end. Dissimilar metal weld between nozzle and safe end is followed by similar metal weld between safe end and pipe. And thus residual stress in dissimilar metal weld can be affected by similar metal weld. Similar metal weld impose bending stress on dissimilar metal weld, which is according to the length of safe end. In this study, simple nozzle model which covers various radius to thickness ratios was proposed to quantify residual stress in dissimilar metal weld based on finite element analyses. As a result, short length of safe end was proved to be more effective to mitigate residual stress in dissimilar metal weld and critical effective length of safe end is provided according to the radius to thickness ratio.

• 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.

• 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 : $0.6mg/{\ell}$

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2006년도 춘계 학술발표회 논문집
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• pp.1334-1339
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• 2006

Dynamic response of buried pipelines both in the axial and the transverse directions on concrete pipe and steel pipe, FRP pipe were investigated through a forced vibration analysis. The dynamic behavior of the buried pipelines for the forced vibration is found to exhibit two different forms, a transient response and a steady state response, depending on the time before and after the transfer of a seismic wave on the end of the buried pipeline. The former is identified by a slight change in its behavior before the sinusoidal-shaped seismic wave travels along the whole length of the pipeline whereas the latter by the complete form of a sinusoidal wave when the wave travels throughout the pipeline. The transient response becomes insignificant as the wave speed increases. From the results of the dynamic responses at the many points of the pipeline, we have found that the responses appeared to be dependent critically on the boundary end conditions. Such effects are found to be most prominent especially for the maximum values of the displacement and the strain and its position.