• Tribology and Lubricants
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• 제27권5호
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• pp.240-248
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• 2011

Mechanical face seal installed in primary heat transport pump used for heavy water reactor prevents leakage of working fluid using thin working fluid film between primary seal ring and mating ring. If the leakage of working fluid exceeds the allowable volume, serious accident can be happened by the trouble of primary heat transport pump. The thinner fluid film exists between primary seal ring and mating ring, the less working fluid leaks out. On the other hand, if the thickness of fluid film is not enough, the life of mechanical face seal will be reduced by friction and wear. Therefore appropriate design is necessary to maximize the performance and life of mechanical face seal. In this study, numerical analysis using finite volume method was conducted to investigate the performance of mechanical face seals which have same deep straight groove and 11 different net coning values. As results, equilibrium clearance between primary seal ring and mating ring, leakage volume of working fluid, friction torque on sealing surface and stiffness of working fluid film were obtained. With increasing net coning value, equilibrium clearance and leakage volume increase, and friction torque and stiffness of fluid film decrease.

• 산업기술연구
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• 제22권A호
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• pp.29-36
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• 2002

A damage detection algorithm using vibration modes is applied to the ring structures and the modal behaviors of the slightly asymmetric rings are examined. Mode shape change, MSER(modal strain energy ratio) and MCR(modal curvature ratio) are investigated to identify the locations of faults or damages The above fault detection parameters are calculated and compared by the finite element analysis on rings with designed local damages. Damages are modeled as a reduced stiffness in the analysis The results show that MSER and MCR can be proper parameters to detect local damages in the ring structures.

• 한국안전학회지
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• 제19권4호
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• pp.101-108
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• 2004

In this study, open conical shells with ring and stringers are analyzed A versatile 4-node shell element which is useful for the analysis of conical shell structures is used and 3-D beam element is used for stiffeners. An improved flat shell element is established by the combined use of the addition of non-conforming displacement modes and the substitute shear strain fields. The proposed element has six degrees of freedom per node and permits an easy connection to other types(beam element) of finite elements. Optimum location and optimum section properties of ring and stinger are obtained. It is shown thai the thickness of conical shell can be reduced about $20\~50\%$ by appropriate location of stiffeners.

• Tribology and Lubricants
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• 제20권6호
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• pp.314-321
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• 2004

Thermal distortion of non-contacting mechanical seals with inclined rubbing surfaces is affected by friction heat between seal ring and seal seat. The circulation fluid along the inclined rubbing surfaces maintains cooling friction heat and lubrication between the sealing surfaces of mechanical seal with an inclined surface. Mechanical seals with inclined sealing surfaces may be useful for reducing the frictional heating and power loss because of the introduction of cooling fluids to the sealing gap between seal ring and seal seat. From the FEM computed result shows that the thermal behavior and von Mises stress of sealing faces with an inclined angle 60 are much reduced in comparison of the conventional mechanical face seal with rectangular sealing surfaces.

• 대한기계학회논문집A
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• 제25권4호
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• pp.602-609
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• 2001

This paper is concerned with the orthotropic problem of diaphragm-type air springs which consist of rubber linings, nylon reinforced rubber composite and bead ring. The analysis is carried out with a finite element method developed to consider the orthotropic properties, geometric nonlinearity using four-node degenerated shell element with reduced integration. Physical stabilization scheme is used to control the zeroenergy mode of the element. The analysis includes an inflation analysis and a lateral analysis of an air spring for the deformed shape and the spring load with respect to the vertical and l ateral deflection. Numerical results demonstrate the variation of the outer diameter, the fold height, the vertical force and the lateral force with respect to the inflation pressure and the lateral deflection.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집A
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• pp.274-279
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• 2000

This paper is concerned with the orthotropic problem of diaphragm-type air springs which consist of rubber linings, nylon reinforced rubber composite and bead ring. The analysis is carried out with a finite element method developed to consider the orthotropic properties, geometric nonlinearity using four-node degenerated shell element with reduced integration. Physical stabilization scheme is used to control the zero-energy modes of the element. An inflation analysis and a lateral deformation analysis of an air spring are carried out. Numerical analysis results demonstrate the variation of the outer diameter, the fold height, the vertical force and the lateral force.

• 대한토목학회논문집
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• 제33권3호
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• pp.865-873
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• 2013

본 연구에서는 부식이나 보강재가 고려된 비균일한 두께를 가지는 파이프라인에 대하여 일정한 외압을 받을 때의 탄성 좌굴하중을 이론적으로 산정하였다. 길이가 매우 긴 원통형 쉘 구조물인 파이프라인을 단순한 링 구조물로 가정하였고, 고유함수를 유도하여 좌굴 임계하중을 산정하였다. 또한, 두께 변화와 두께가 감소된 구간의 범위에 따른 변수해석을 수행하였다. 이론식에 의해 산정된 좌굴 임계하중 결과를 유한요소해석 결과와 비교하여 검증하였고, 두 결과는 잘 일치함을 알 수 있었다.

• 호남수학학술지
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• 제28권4호
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• pp.499-511
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• 2006

It is well-known that every finitely generated torsion-free module over a principal ideal domain is free. This will be generalized. We deal with ideals of the finite, external direct product of certain rings. Finally, if M is a torsion-free, finitely generated module over a reduced, Noetherian ring A, then we prove that Ms is a projective module over As, where $S=A{\setminus}(A)$.

• 한국추진공학회지
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• 제4권3호
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• pp.64-73
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• 2000

본 체결부는 필라멘트 와인딩으로 제작된 연소관, 복합재 쐐기 그리고 알루미늄 내부 링으로 구성된다. 여기서 연소관은 헬리컬 층과 후프 층으로 이루어져 있다. 이러한 복합재 연소관의 성능 향상을 위해 체결부의 설계 변수에 따른 유한 요소 응력 해석이 수행되었다. 이때 접착 층을 난-소성 거동 재질로, 쐐기부와 알루미늄 링간의 접촉 상태는 ABAQUS의 접촉 표면 요소로 모사 되었다. 또한 해석 결과의 정확성을 입증하기 위해 내압에 의한 체결부 밀림 변위와 연소관 몸체의 원주 방향 변형도를 수압 시험과 비교하였다. 쐐기와 알루미늄 링간의 완벽 접착은 쐐기와 연소관간의 접착 층에 높은 전단 변형을 발생시켜 체결부 조기 파괴의 원인이 된다. 쐐기와 알루미늄 링간의 미 접착은 쐐기와 연소관사이의 접착 층 전단 응력을 감소시키는 반면 내부 알루미늄 링의 미끄러짐 거동으로 체결부 복합재의 반경 방향 변형을 증가시켜 파괴를 유발하였다. 그러나 쐐기부와 알루미늄 링간의 미접착 상태에서, 원주 방향 와인딩으로 체결부 지점을 보강한 경우, 알루미늄 링의 미끌어짐이 억제되어 체결부 지점의 복합재 원주 방향 변형값이 감소했다.

• 대한수학회보
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• 제54권2호
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• pp.559-571
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• 2017

We investigate modules M having the injective property relative to nonsingular modules. Such modules are called "$\mathcal{N}$-injective modules". It is shown that M is an $\mathcal{N}$-injective R-module if and only if the annihilator of $Z_2(R_R)$ in M is equal to the annihilator of $Z_2(R_R)$ in E(M). Every $\mathcal{N}$-injective R-module is injective precisely when R is a right nonsingular ring. We prove that the endomorphism ring of an $\mathcal{N}$-injective module has a von Neumann regular factor ring. Every (finitely generated, cyclic, free) R-module is $\mathcal{N}$-injective, if and only if $R^{(\mathbb{N})}$ is $\mathcal{N}$-injective, if and only if R is right t-semisimple. The $\mathcal{N}$-injective property is characterized for right extending rings, semilocal rings and rings of finite reduced rank. Using the $\mathcal{N}$-injective property, we determine the rings whose all nonsingular cyclic modules are injective.