• 한국산학기술학회논문지
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• 제9권2호
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• pp.480-486
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• 2008

유한요소 해석을 수행하여 엘보우의 거동을 파악하였으며 해석 시 엘보우의 휨 각도와 엘보우계수를 주요변수로 사용하였다. 사용하중은 엘보우 축이 형성하는 평면 내에 작용하는 휨 모멘트를 사용하였으며 해석 결과를 이론적 정해 법으로 유도된 ASME 코드 식과 비교하였다. 또한 엘보우 단면의 응력상태와 유연도 특성을 이용하여 엘보우 단면의 타원변형으로 인한 엘보우의 기하학적 비선형 특성을 설명하였다.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 2000년도 춘계 학술발표회 논문집
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• pp.229-235
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• 2000

A study on the improvement of anti-abrasion nature of curved ducts for high-velocity gas-solid flow which are typically equipped in a coal-burned steam power plant has been investigated numerically and experimentally. To reduced the abrasion of pipe by particle, we have tried to form the vortex flow field in the region where flow changes its direction , modelled with two different shapes. 22.5$^{\circ}$and 90$^{\circ}$ elbows. the governing equations for three -dimensional , turbulent flow fields are discretized by FVM and solved bySIMPLE algorithm . From the numerical analysis, the new designed elbows for reducing abrasion have been developed. Numerical results are compared with the experimental abrasion data which are obtained from one of the operating coal burned steam power plants in Korea. Comparison of these results show that the developed elbows have much more durability than the original one.

• Journal of Advanced Marine Engineering and Technology
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• 제34권6호
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• pp.816-824
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• 2010

본 논문에서는 쓰레기 이송관로내의 물체에 작용하는 힘을 분석하고 그 물체의 운동방정식 확립하였다. 그 운동방정식은 1계 비선형 미분방정식이 되며 이것의 일반해를 이용하면 쓰레기 이송관로내 물체의 속도를 구할 수가 있다. 물체의 속도는 엘보우와 같은 쓰레기 이송관로의 곡선부에서 내벽의 충돌속도가 되므로 충돌시 물체의 운동에너지를 계산할 수 있고, 따라서 필요한 내벽의 충격강도를 알 수가 있다. 하나의 예로써 쓰레기 이송관로내 공기의 속도가 30m/sec일 때 물체의 속도를 계산하여 그래프로써 나타내었으며, 이것으로부터 물체가 내벽에 충돌할 때의 운동에너지를 계산할 수 있도록 하였다. 또한 용융주조 현무암 튜브를 철강파이프 내면에 보호벽으로 씌운 복합재료 파이프에 추를 자유낙하시켜 충격을 주는 방식으로 충격시험을 한 결과를 제시하였으며, 그 결과에 의하면 용융 주조 현무암 튜브는 쓰레기 이송관로의 내면 보호벽으로 충분한 충격강도를 가지는 것이 판명되었다.

• 한국재료학회지
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• 제24권2호
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• pp.87-92
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• 2014

The Notched Ring Test(NRT) has proven to be very useful in determining the slow crack growth behavior of polyethylene pressure pipes. In particular, the test is simple and an order of magnitude shorter in experimental times as compared to the currently used Notched Pipe Test(NPT), which makes this method attractive for use as the accelerated slow crack growth test. In addition, since the NRT specimen is taken directly from the pipe, having maintained the cross-section, processing induced artifacts that would affect the slow crack growth behavior are not altered. This makes the direct comparison to the slow crack growth specimen in pipe from more meaningful. In this study, for comparison with other available slow crack growth methods, including the NPT, the stress intensity factor equation for NRT specimen was developed and demonstrated of its accuracy within 3% of that obtained from the finite element analysis. The equation was derived using a flexure formula of curved beam bending along with numerically determined geometric factors. The accuracy of the equation was successfully tested on 63, 110, 140, 160, 250, and 400 mm nominal pipe diameters, with crack depth ranging from 15 % to 45 % of the pipe wall thickness, and for standard dimensional ratio(SDR) of 9, 11, and 13.6. Using this equation the slow crack results from 110SDR11 NRT specimen were compared to that from the NPT specimen, which demonstrated that the NRT specimen was equivalent to the NPT specimen in creating the slow crack, however in much shorter experimental times.

• 소성∙가공
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• 제3권1호
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• pp.23-37
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• 1994

The upper bound element technique(UBET) is used to analyze the final stage of the axisymmetric forward extrusion. Kinematically admissible velocity field involving curved surface of velocity discontinuity is assumed. The required power to arise the piping defect is obtained and is compared with Aviture's solution a the same condition. Conditions for inception of the cavity and development of the pipe are predicted. The internal radius of the pipe and critical length of billet are also determined. Experiments are carried out for extrusion with lead specimens to investigate the piping phenomena. The theoretically predicted results showed reasonably good agreement with the experimental observation.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.427-428
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• 2009

The authors investigated anomalous nanoporous structures of aluminum oxides during the Al anodization process. We implemented two-steps anodizing process for the electrolyte of oxalic acid. As increasing DC voltages, lattice constants are proportionally increased. For the curved surface, the surface electric field was distorted so that the nanoporous pipe channel changed to a cone-type shape. We confirmed the periodicity by using the FFT(Fast Fourier Transform) analysis.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2794-2797
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• 2008

The pneumatic waste collection system, which is a complete solution for solving the waste collection problems, are constructed in many countries all over the world. However, research data for piping network design are insufficient. In this paper the pressure losses of the straight and curved pipes, pipe junctions are obtained using the numerical method in order to investigate the optimal pipe network design for the waste collection system.

• Wind and Structures
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• 제1권1호
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• pp.59-66
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• 1998

The vibrations of bodies subjected to fluid flow can cause modifications in the flow conditions, giving rise to interaction forces that depend primarily on displacements and velocities of the body in question. In this paper the linearized equations of motion for bodies of arbitrary prismatic or cylindrical cross-section in two-dimensional cross-flow are presented, considering the three degrees of freedom of the body cross-section. By restraining the rotational motion, equations applicable to circular tubes, pipes or cables are obtained. These equations can be used to determine stability limits for such structural systems when subjected to non uniform cross-flow, or to evaluate, under the quasi static assumption, their response to vortex or turbulent excitation. As a simple illustration, the stability of a pipe subjected to a bidimensional flow in the direction normal to the pipe axis is examined. It is shown that the approach is extremely powerful, allowing the evaluation of fluid-structure interaction in unidimensional structural systems, such as straight or curved pipes, cables, etc, by means of either a combined experimental-numerical scheme or through purely numerical methods.

• 한국터널지하공간학회 논문집
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• 제26권3호
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• pp.243-254
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• 2024

현재 국내 지역의 산업 발달로 인해 주요 도심은 물론 주변 도시 지역에도 건축물이 포화 상태이다. 이에 따라 사람들의 관심은 지하공간으로 쏠리게 되었고, 특히 도시개발에 있어서 터널은 광범위하게 활용되고 있다. 이에 따라 터널 및 터널굴착공법에 대한 연구가 활발히 진행되고 있다. 그러나 이수식 쉴드 TBM 사용 시 슬러지 배출관의 마모 및 파손 문제에 대한 연구는 부족한 실정이다. 따라서 본 논문에서는 기존 슬러지 배출관에 사용된 L자형 곡관을 T자형 곡관으로 변형하여 슬러지를 이동시켰다. 그 결과, L자형 곡관에 비하여 T자형 곡관이 슬러지 배출 시 곡관에 미치는 영향이 감소하는 것을 확인할 수 있었다. 이러한 결과를 바탕으로 이수식 쉴드 TBM 장비 사용 시 T자형 곡관을 사용하면 슬러지 배출관의 마모를 최소화할 수 있을 것으로 기대된다. 이는 결국 터널 공사 시 곡관 교체나 추가 용접에 따른 비용을 절감하는 등 경제적 이익으로 이어질 것으로 기대된다.

• Nuclear Engineering and Technology
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• 제55권10호
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• pp.3571-3580
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• 2023

The application of the induction bending process to pipe systems in various industrial fields is increasing. Recently, efforts have also been made to apply this bending process to nuclear power plants because it can innovatively reduce welded parts of the curved pipes, such as elbows. However, there have been no cases of the application of induction bending to the piping of nuclear power plants. In this study, the applicability of the P91 induction bending piping for the sodium-cooled fast reactor PGSFR was validated through high temperature low cycle fatigue tests and creep tests using P91 induction bending pipe specimens. The tests confirmed that the materials sufficiently satisfied the fatigue life and the creep rupture life requirements for P91 steel at 550 ℃ in the ASME B&PV Code, Sec. III, Div. 5. The results show that the effects of heating and bending by the induction bending process on the material properties were not significant and the induction bending process could be applicable to piping system of PGSFR well.