• Journal of the KSME
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• v.18 no.3
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• pp.57-61
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• 1978

안전벨브설비의 기계적설계와 해석에관련된 가장 중요한 고려사항중의 하나는 설비내의 임계점을 찾아내고 그 점에서의 모우멘트를 계산하는 것이다. 만약 굽힘모우멘트를 적절히 계산하지 않으 연 기술기순에 포함된 하중 및 응력기준에 합격할 수 없을 것이다. 이 모우멘트를 결정하는데 최 소한도 본 부록의 2부에 설명된 다음 하중들을 포함함이 바람직하다. 1. 열팽창 2. 사하중 3. 지진 4. 벨브 송출로부터의 반작용력 5. 기타 기계적하중 안전밸브설비의 핵석에서 교차점, 엘보우, 변이점등을 포함한 모든 중요단면 및 기타 관련된 배 관, 용기및 배관설비와 상호작용하는 그들의 지지점들을 포함함이 바람직하다. 안전밸브설비와 그 에 관련된 배관을 직선 또는 곡선 요소들을 연결된 하나의 통합된 질량계로서 모형화하는 것이 가장 적절하다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.12
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• pp.1063-1071
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• 2008

This paper provides a failure pressure evaluation model for local wall-thinned elbows. In this study, parametric finite element analyses are performed on the elbows containing local wall-thinning defect at their intrados and extrados, and the failure pressures are obtained from the analysis results by applying a local failure criterion that was validated by real-scale pipe tests. An evaluation model including the effects of thinning depth, length, circumferential angle, thinning location, and elbow geometries on the failure pressure is derived based on the evaluated failure pressures. The proposed model agrees well with the results of finite element analyses and reasonably estimates the dependence of failure pressure on the wall-thinning dimensions and elbow geometries. Also, the comparison with experimental data demonstrates that the proposed evaluation model can accurately predict the failure pressure of local wall-thinned elbows.

• Journal of Welding and Joining
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• v.11 no.1
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• pp.21-32
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• 1993

A cracking failure of a austenitic stainless steel elbow in a naphtha cracking line in a petrochenmical plant occurred, resulting in leakage of organic compound flowing inside the elbow. Due to the failure, emergency shutdown of the plant was enforced to repair the troubled part of the line. The repair cost as well as production loss during the unscheduled plant shutdown has cost the company a great amount of financial loss. In this studies, a failure analysis of the cracked elbow was performed using NDT, chemical analysis, microstructural analysis including optical microscopy as well as scanning electron microscopy with EPMA, mechanical testings such as tensile testing, hardness testing and Charphy impact test fractography. The results indicated that several problems such as a welding defect and presence of a detrimental phase which was found to be relate to improper postforming heat treatment process was identified and the failure was concluded to be due to a low temperature embrittlement of the defect-containing elbows.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.13 no.1
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• pp.84-91
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• 2017

This paper is proposed to select the optimal finite element type in finite element analysis. Based on the NUREG reports, static analyses were performed using a commercial analysis program, $ABAQUS^{TM}$. In this study, we used a nonlinear kinematic hardening model proposed by Chaboche. The analysis result of solid elements by inputting the same material constants was different from the results of the NUREG report. This is resulted from the difference between shell element and solid element. Therefore, the material constants that have similar result to the experimental result were determined and compared according to element type. In case of using solid element for efficient finite element analysis, we confirmed that the use of C3D8I element type(incompatible mode 8-node linear brick element) leads the accurate result while reducing the analysis time.

• Journal of the Korean Society of Safety
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• v.18 no.3
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• pp.39-45
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• 2003

The failure mode of a pipe due to local wall thinning is increasingly more attention in the nuclear power plant industry. To assess the integrity of locally wall thinned pipe, it is necessary to perform many simulations under various conditions. Because the modeling for locally wall thinned elbow is more complicated than that of straight pipe the efficient modeling method for finite element analysis is necessary. In this study, the more simple efficient modeling method of three-dimensional finite element analysis for locally wall thinned elbow has been suggested and verified. And using the method, the failure mode of local wall thinned elbows that have different thinning lengths and circumferential angles is evaluated. From the results, we concluded that the collapse load of elbows has been decreased by the increase of wall thinning shape factors such as thinning lengths and circumferential angles.

• Journal of the Korean Applied Science and Technology
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• v.36 no.3
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• pp.758-765
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• 2019

The purpose of the this study was to determine the comparative analysis of body muscle activities in plank exercise with and without thera-band. Twelve healthy adult males(age, $21.75{\pm}.57$ years; height, $173.33{\pm}1.34cm$; body mass, $65.92{\pm}1.64kg$; and BMI, $21.93{\pm}.46kg/m^2$) participated in this study as subjects. Plank exercises(full, elbow, side, and reverse plank) were performed with four different thera-band in without(WT), red color(RT), blue color(BT), and siver color(ST). We measured the muscle activities of the erector spinae(ES), deltoideus p. acromialis(DA), external oblique(EO), rectus abdominis(RA), rectus femoris(RF), latissimus dorsi(LD), pectoralis major(PM), and biceps femoris(BF). The research findings were as follows. ES and DA muscle activities were greatest during full plank performed with the WT(p<.05). EO, RA, RF, and PM muscle activities were greatest during full plank performed with the ST(p<.05). ES and DA muscle activities were greatest during elbow plank performed with the WT(p<.05). RF and PM muscle activities were greatest during elbow plank performed with the ST(p<.05). ES, EO, RA, RF, LD, PM, and BF muscle activities were greatest during side plank performed with the ST(p<.05). DA, EO, RA, RF, LD, PM, and BF muscle activities were greatest during reverse plank performed with the ST(p<.05). These results are expected to serve as reference materials for plank exercise applications in training programs for body muscle strengthening.

• Journal of the Korean Society of Safety
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• v.23 no.3
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• pp.17-24
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• 2008

Elbows with various shapes of local wall thinning were numerically analyzed by finite element method to get load-displacement curves and the maximum loads. Results were compared with the experimental data obtained by another study. Elastic-plastic analysis were carried out under the combined loading conditions of internal pressure and in-plane bending loads. Two types of bending loads were considered such as elbow opening mode and elbow closing mode. Also, two different wall thinning geometries were modeled. Wall thinning area located extrados or intrados of elbow inner surface was considered. Longitudinal and circumferential lengths of the thinning area and the thinned thickness were varied for analysis. The results showed that the maximum load of the wall-thinned elbow decreased with increasing of the circumferential thinning length and the thinned thickness in both of extrados and intrados thinning locations in both loading types. The maximum load obtained by the analysis were in good agreement with the experimentally measured maximum load with the same wall thinning type and dimensions. This supports accuracy of the analysis results obtained in this study.

• Clinics in Shoulder and Elbow
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• v.7 no.1
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• pp.35-40
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• 2004

Purpose: The aim of this study was to investigate effects of calcific lesion on shockwave therapy of the tennis elbow. Materials and Methods: twenty-four patients with refractory tennis elbow were treated with shock waves. The patients were evaluated by assessment of pain using visual analog scale (VAS) and simple elbow test (SET). Comparision of clinical outcomes for the patients with and without calcification in the extensor tendon and/or cortical irregularity of lateral condyle was tried to determine if this could be a possible prognostic factor in clinical settings. Overall clinical outcomes were evaluated by Roles and Maudsley score at 12 months after ESWT. Results: Significant improvement of symptoms were observed in 20 (83 %) patients at 12 months follow up according to Roles and Maudesley scores. The patients with calcification and/or cortical irregularity improved significantly better, when compared to the patients without calcification and/or cortical irregularity at follow up. Conclusion: This study suggests that shock waves therapy could be considered as effective and noninvasive treatment modality for refractory tennis elbow. Also calcific deposit in extensor tendon and/or cortical irregularity of the lateral epicondyle was seem to be good prognostic factor for shock wave therapy for tennis elbow

• Transactions of Materials Processing
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• v.26 no.1
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• pp.11-17
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• 2017

In this study, process analysis of elbow-shaped tubes using a mandrel has been performed. To reach the final shape within the dimensional tolerance, the process analysis has been performed at various processing parameters such as tube dimensions, the curved cutting surface and the radius of curvature. The area outside the boundary of the target shape was expressed as a quantitative index to analyze the formability. The validation experiments have also been performed in order to increase the reliability of the process analysis. For the processing of elbow-shaped tubes, it is preferable to make the angle of the portion where the punch touches the tube smaller than the opposite angle. And the convex cutting surface is advantageous due to the increased contacts between the punch and the tube ends during the bending process. Elbow tube having larger radius of curvature shows higher dimensional accuracy due to the relatively uniform strain distribution.

• Journal of the Korean Society of Safety
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• v.20 no.1 s.69
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• pp.55-61
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• 2005

The purpose of this study is to investigate the effect of circumferential location of local wall thinning defect on the collapse behavior of an elbow. Thus, the present study conducts three-dimensional finite element analysis on the 90-degree elbow containing a local wall thinning at intrados, crown and extrados of bend region and evaluates the collapse moment of wall thinned elbow under various thinning shapes and loading conditions. Combined internal pressure and bending moment are considered as an applied load. The internal pressure of $0\~20MPa$ and both closing and opening mode bending are employed. The results of analysis show that the reduction in collapse moment of the elbow by local wall thinning is more significant for a defect locating at crown than for a defect locating at intrados or at extrados. Also, the effect of internal pressure on the collapse moment of wall thinned elbow depends on the circumferential location of thinning defect and applied bending mode.