• Title/Summary/Keyword: Bending

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Analytical and Experimental Study on the Quality Stability of Multi Roll Forming Process (멀티 롤 포밍 공정의 품질 안정성에 대한 해석 및 실험적 연구)

  • Son, Jae-Hwan;Han, Chang-Woo;Ryu, Kyung-Jin;Kang, Hae-Dong;Kim, Chul-Hong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.16 no.10
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    • pp.6977-6984
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    • 2015
  • It is faced with the necessity of multi roll forming process of the ball slide rail which is made by adding the separate manufacturing processes, piercing, bending, trimming, to the roll forming process of a continuous plastic deformation, to improve the quality. However, the vibration and noise of the press machine in this process leads to the quality degradation of slide rail manufactured in this process. In this study, the roll was designed considering the optimal strain rates by the roll forming program with finite element method. And to estimate the static stability of the multi process the Von-Mises stress and deformation on the press was calculated with a structural analysis program. Also, to avoid driving systems in the resonance region their natural frequencies in the 1st and 2nd mode were calculated through the modal analysis. To verify its dynamic stability improvement the magnitudes of noise and vibration in the existing and studied system were compared using a microphone and accelerometers. And the widths and surface roughnesses of the rails which had been produced in the existing and studied process were measured. Therefore, it is known that multi roll forming process is stable in the analytical and experimental study.

Usefulness Evaluation of Merchant Auxiliary Equipment of Body Type Changing Suitable for X-ray Table Integral Type (체형변화에 적합한 X-선 검사대 일체형 Merchant 보조장비의 유용성 평가)

  • Seoung, Youl-Hun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.14 no.6
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    • pp.2773-2779
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    • 2013
  • The purpose of this study was to evaluate of the usefulness and to develop new auxiliary equipment that can bending angle of the bone of the knee various depending on the thickness of the thigh of the human. The subjects agreed for research purposes and were selected from normal person who do not have past knee-related diseases and grouped thin group A and thick group B for the thigh. We set in order to obtain images in the axial direction of the bones of the knee, $35^{\circ}$ to increase by $5^{\circ}$ angle of knee flexion, $45^{\circ}$, to $55^{\circ}$, and we performed combinations of 9 tests by incident angle X-ray per each angle, $40^{\circ}$, $50^{\circ}$ and $60^{\circ}$. As a result, we have developed an Merchant auxillary equipment of X-ray table integral type in radiographic images which was easy to use and could take images of various integral knee joint angles adjusting different body types. Using the auxiliary equipment, in the case of X-ray incident angle $50^{\circ}$ and $60^{\circ}$ with the knee flexion angle of $40^{\circ}$ in group A, and in group B, Knee flexion angle of $45^{\circ}$ and $35^{\circ}$, the X-ray incident angle at $60^{\circ}$, excellent images were derived. Future, it would be very useful in the examination of patients with a variety of body types.

The quality improvement study on the crack of heat exchanger lubricating oil port in military aircraft (군용항공기 열교환기 윤활유 유입포트 균열개선 연구)

  • Park, Sung-Jae;Choi, Jae-Ho;Choi, Gil-Gyu;Lee, Dong-Ki
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.21 no.4
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    • pp.164-172
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    • 2020
  • The fuel oil/heat exchanger installed in military aircraft is a device that cools the lubricant oil supplied to other devices, such as an AMAD, and a hydraulic pump using the low temperature of the fuel is cracked at the AMAD lubricant inlet port. If a crack in the heat exchanger occurs, the lubricant oil supplied to other equipment is not cooled. Therefore, the flight can no longer be performed. In this study, non-destructive inspection and microscopic examination of the fracture surface of the oil port were performed to analyze the crack tendency. The oil pipe connected to the oil port is a titanium pipe, which is fastened with over torque and has been identified as the leading cause of heat exchanger oil port cracks. In addition, it was verified as the main reason for cracking by finite element analysis. The material and diameter of the pipe were changed to improve this defect, and the applied torque was adjusted. In addition, the bending value of the pipe was adjusted to minimize the fatigue accumulation due to pulsating pressure. As a result, no cracks occurred on the heat exchanger via the ground test after the installation of an improved pipe under the same conditions.

Structural Performance and Behavior of Concrete Floating Container Terminal by Live Load Distributions (활하중 분포에 따른 콘크리트 부유식 컨테이너 터미널의 구조성능 및 거동)

  • Lee, Du-Ho;Jeong, Yun-Ju;You, Young-Jun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.19 no.1
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    • pp.72-80
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    • 2015
  • In this study, comparative analysis has been performed with regard to a bending stress and deformation at bottom slab of a concrete floating container terminal by live load distributions. In addition, a structural performance and behavior of the floating structure is considered using a numerical analysis. Through reviewed structural performance of a floating structure by live load distribution, the structure presented tensile behavior by two live load cases (A, B, D-type). Then, the other live load cases (C, E, F, G, H, I, J-type) shows compressive behavior. Especially, immoderately compressive stress was generated on bottom slab at specific load distribution. but, that should be decreased through controling buoyancy pre-flexion. Through reviewed structural behavior, slopes of structure by four live load cases (B, E, F, H-type) were exceeded in design criteria of mega-float. It should be estimated that it get out of the load case at loading container. In all, the present study can be considered as a benchmark of a floating container terminal in the absence of analysis and will be used to guide-line about serviceability of concrete floating container terminal.

Analytical Study of Ultimate Behavior of Steel Cable-stayed Bridges (완성계 강사장교의 극한 거동의 해석적 연구)

  • Kim, Seungjun;Im, Seok-Been;Lee, Kee-Sei;Kang, Young-Jong
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.32 no.2A
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    • pp.85-95
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    • 2012
  • This paper presents an investigation on the ultimate behavior of steel cable-stayed bridges using nonlinear finite element analysis method. Cable-stayed bridges exhibit various geometric nonlinearities as well as material nonlinearities, so rational nonlinear finite element analysis should be performed for investigation of the ultimate behavior. In this study, ultimate behavior of steel cable-stayed bridges was studied using rational ultimate analysis method. Nonlinear equivalent truss element and nonlinear frame element were used for modeling the cable, girder and mast. Moreover, refined plastic hinge method was adopted for considering the material nonlinearity of steel members. In this study, the 2-step analysis method was used. Before live load analysis, initial shape analysis was performed in order to consider the dead load condition. For investigation of the ultimate behavior of steel cable-stayed bridges, analysis models which span length is 920.0 m were used. Radiating type and fan type were considered as the cable-arrangement types. With various quantitative evidences such as load-displacement curves, deformed shapes, locations of the yield point or region, bending moment distribution and so on, the ultimate behavior of steel cable-stayed bridges was investigated and described in this paper.

Correlation Analysis Between Lumbar Scoliosis of X-ray and HIVD of L-spine MRI in LBP Patients who Visit Korean Medicine Hospital (한방병원에 요통으로 내원한 환자에서 X-ray상 요추측만과 MRI상 HIVD와의 연관성 분석)

  • Kim, Kil-Hwan;Choi, Young-Jun;Kwon, Ok-Jun;Joo, Young-Kuk;Song, Seung-Bae;Song, Gwang-Chan;Seo, Ji-Yeon;Choo, Won-Jung
    • The Journal of Churna Manual Medicine for Spine and Nerves
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    • v.11 no.1
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    • pp.41-51
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    • 2016
  • Objectives : This study is planned to classify Correlation between Cobbs Angle of Lumbar scoliosis and prevalence of Lumbar Intervertebral Disc. Methods : We Measured the lumbar scoliosis angle of the 114men and 91 women patients with lumbar pain in Bucheon Jaseng Korean Medicine Hospital. We use Cobb's angle method for measuring the lumbar scoliosis. And We use Magentic Resonance Imaging(MRI) for classifying the patient who has lumbar intervertebral disc or not. Results : 1.There was no statistical relation between the Cobbs angle and gender(P>0.05) 2.There was no statistical relation between the Cobbs angle and age(P>0.05) 3.There was significant relation between the direction of lumbar scoliosis and the direction of disc herniation(P<0.05) 4.There was no statistical relation between on the Cobbs angle and disc herniation. The more severe of lumbar scoliosis has not tendency of disc herniation. 5.There was no statistical relation between lumbar scoliosis Cobbs Angle on HIVD of L-spine patient and direction of disc herniation on horizontal plane. Conclusions : The direction of disc herniation has tendency of the opposite direction of lumbar scoliosis. When disc herniation, opposite side bending broad intervertebral foramen and reduce pressure.

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A comparative study to evaluate the effect crook sitting position and understanding of test in pulmonary function test on healthy individuals (건강한 성인에서 자세변화와 검사방법의 이해도가 폐기능검사 결과에 미치는 영향)

  • Yon, Jung-Min;Lee, Og-Kyoung
    • Journal of Digital Convergence
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    • v.15 no.5
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    • pp.263-269
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    • 2017
  • Pulmonary function test (PFT) is a test method to determine respiratory disease. In order to obtain accurate PFT results, it is absolutely necessary to induce the inspector and cooperate with the patient. This study was to observe the importance of understanding and posture of the patient in spirometry. In 2016, 110 healthy experimenter performed spirometry; 1) only heard the explanation, 2) watching video and inspector,s demonstration, 3) twisting legs and bending shoulder. FVC, $FEV_1$, $FEV_1/FVC$, $FEF_{25-75%}$, PEF were measured by spirometry. FVC, $FEV_1$, $FEV_1/FVC$, $FEF_{25-75%}$, PEF were significantly increased before and after the understanding the test method. There was a significant difference in FVC, $FEV_1$, and PEF in the false posture. Reproducibility was significantly different in the experimenter' comprehension and false posture. This study provides accurate understanding of the patient and correct posture should be maintained during the examination to obtain correct and reproducible results of PFT.

THE EFFECT OF PLASMA-TREATED POLYETHYLENE FIBER ON THE FLEXURAL STRENGTH OF COMPOSITE RESIN IN VARIOUS APPLIED PORTIONS (플라스마 처리된 폴리에틸렌 섬유의 적용 부위가 복합 레진의 굴곡 강도에 미치는 영향)

  • Oh, Yong-Jin;Oh, Nam-Shik;Lee, Keun-Woo
    • The Journal of Korean Academy of Prosthodontics
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    • v.35 no.2
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    • pp.401-412
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    • 1997
  • There has been many researches aimed at reinforcing the strength of resin, and these have led to the development and use of numerous materials in recent years. A case in point, is the recent development of plasma-treated polyethylene fiber which has been used mainly in fixed provisional restoration to reduce the incidence of fractures. This study aims at assessing whether plasma-treated polyethylene fiber as applied to composite resin is effective in increasing the flexural strength and how applied portions affect this. Twenty-four applied and eight unapplied composite resin bars were fabricated. Twenty-four applied specimens were divided into three groups. Plasma treated polyethylene fiber was applied to the groups each with different portions of composite resin. In the first group, plasma-treated polyethylene fiber was not applied. In the second group, fiber was applied to the compression side of composite resin. Fiber was applied to the tension side in the third group, while fiber was embedded in the tension side of the composite resin in the fourth group. Each specimen was tested by use of a three-point bending strength test with an instron testing machine, and the flexural strength was calculated. The following results were obtained. : 1. Under the conditions of this study, the third and fourth groups demonstrated a statistically greater flexural strength compared to the first and second groups. 2. But there was no statistically significant difference, not only between the first group and the second group, but also between the third group and the fourth group. Taken together, it can be concluded that plasma-treated polyethylene fiber applied to composite resin is an effective method in increasing flexural strength, and the best way of increasing the flexural strength is by application of plasma-treated polyethylene fiber to the tension side, or the embedding of same in composite resin. It must be mentioned however that this test used a static single-load test method. This method determined the maximum stresses that could be tolerated, but this might not be valid where the prediction of clinical failure is concerned. In order therefore to clinically utilize plasma-treated polyethylene fiber to reinforce the composite resin, it is suggested that a further study which considers the various loads be undertaken.

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Mechanical Properties and 3D CAD Images of the Appearance of Knitted Fabric with Acetate/Polyester Composite Yarn by Different Yarn Twisting Methods (연사방법에 따른 아세테이트/폴리에스터 복합사 편성물의 역학적 특성 및 3D CAD System에 의한 외관특성)

  • Kim, So-Jin;Jeon, Dong-Won;Park, Young-Hwan
    • Textile Coloration and Finishing
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    • v.18 no.1
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    • pp.33-43
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    • 2006
  • The purpose of this study was to eximine the effect of different yam twisting methods on mechanical properties and 3D CAD images of plain knitted fabrics made of composite yarns. Six yams were used in this study: four different composite yams of the six consist of acetate and functional polyester (Poly-m) with the ratio of 70:30, and the rest two are the original acetate $100\%$ yam and the poly-m $100\%$ yarn. The four kinds of composite yarns were processed in combinations of twisting processes such as interlacing, false twisting, two for one twisting, combined twisting and single covering, and the two original yams were knitted without any twisting process. Sixteen mechanical properties of all the six knitted fabrics, knitted under the same knitting conditions, were measured by KES-FB system with the outer knit condition. The results were as follows; 1) When the sample applied with the false twisting process at the temperature as high as $220^{\circ}C$, ENT, B, HB, G and RC values of samples increased which leads to increasing dimensional stability. 2) To gain the high bending and shear properties in the single covering process, selecting the core yarn with such properties is the most important factor. 3) Interlacing process effected to increase RC value. 4) False twisting process after interlacing process gave bulkiness and un-interlaced part in yam was increased SMD value. The SMD value of the kilted fabric of the composite yarn, which was put through the combined twist process, was higher than those of which simple process such as the two for one twist or the single covering process applied. In order to achieve the silk-like surface feel of knitted fabric, the sin91e covering process is recommended. 5) Examining the simulation images of the knifed fabrics of composite yarn, which were generated by the 3D CAD system based on the mechanical properties of the fabric, led that appearance could be changed as different twisting methods were applied.

A Study on the Finite Element Analysis and Management Criteria by Applying UPRS Method in the Subway Station (기존 지하철정거장 비개착공법 적용시 유한요소 해석과 관리기준에 관한 연구)

  • Cho, Byeong Joon
    • Journal of Korean Society of Disaster and Security
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    • v.12 no.4
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    • pp.43-52
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    • 2019
  • To analyze the influence on the stability, resulting from application of upgrade pipe roof structure (UPRS) method to the structure existed under subway Station, physical properties of a ground, elasticity and elasto-plastic theories, including displacement analysis of finite elements, stress analysis of finite elements, displacement caused by steel pipe propulsion and internal excavation, and stress change in a steel pipe, were introduced. Then, the influence on structural stability when applying the UPRS method was compared and reviewed based on the construction management standard of the Ministry Land, Infrastructure and Transport and foreign sources, using numerical analysis with a model which assumes that each microelement divided into a structurally stable point consists of the connection of finite points. As a result of the finite element analysis, 7.21 mm maximum displacement, 1/3,950 angular displacement, 70.28 MPa bending compressive stress of steel pipe structure constructed with UPRS (non-excavation) method and 477.38 MPa maximum shear strength were within their allowable standards (25.00 mm, 1/500, 210.00 MPa and 120.00 MPa, respectively), and therefore, the results showed that the design and construction are stable.