• 에너지공학
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• 제24권4호
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• pp.55-62
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• 2015

It is expected that the size of welding defect affects the mechanical performance of welded medium density polyethylene (MDPE) pipe joints. In this study, butt fusion welded MDPE pipe joints with a single spherical or planar defect of various sizes were studied using experimental crush testing and also by finite element method. The crush test showed that the mechanical performance of crush was not affected by the size and geometry of a single welding defect when the defect size was increased to 45% of the pipe's wall thickness. The simulation results indicated that the effect of the single welding defect on the Von Mises stress distribution near the defect explained the reason of the test results.

• 항공우주시스템공학회지
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• 제4권3호
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• pp.1-5
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• 2010

Understanding the crushing behaviour of aluminum honeycombs under dynamic loading is useful for crash simulations of vehicles and for design of impacting energy absorbers. In the study of honeycomb crushing under quasi-static, dynamic loading, the most important parameter is crush strength. Crush strength is indicated to energy absorption characteristic of aluminum honeycomb. In this study, Using Finite Element Analysis carried out crush strength of hexagonal aluminum honeycomb then the results was compared with Quasi-static test. Consequently, Crush strength is different in quasi-static loading and dynamic loading about 16%.

• 한국자동차공학회논문집
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• 제4권6호
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• pp.216-222
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• 1996

This paper presents a computational technique to predict roof crush resistance in early design stage of passenger car development. This technique use a simple F.E. model with nonlinear spring elements which represent plastic hinge behavior at weak areas. By assuming actual sections as equivalent simple sections, maximum bending moments which weak areas in major members can stand are theoretically calculated. Results from prediction of roof crush resistance are correlated well with test results.

• 대한기계학회논문집A
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• 제36권8호
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• pp.935-943
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• 2012

철도차량에서 있어서 충돌 시 철도차량의 전두부가 운전자 및 승객의 공간을 침투하는 위험성을 항상 내포하고 있다. 이러한 위험성을 줄이기 위해서, 철도차량의 충돌에 관한 연구들이 전세계적으로 활발히 진행 중에 있다. 2010 년에 미국연방법규인 CFR (Code of Federal Regulations)은 단부 구조물 (end frame)의 구성요소인 충돌 기둥 및 모서리 기둥에 대한 압괴조건을 추가하여 개정되었다. 본 연구에서는 충돌 기둥에 대해서 CFR 법규에 명시된 조건에 대해서 압괴해석 및 압괴시험을 수행하였고, 법규에서 근본적으로 고려한 충돌체와의 충돌해석을 수행하여 그 결과들을 비교하였다. 이를 통하여, 단부 구조물의 압괴특성과 충돌특성을 파악하고 해석의 신뢰성을 검토하여 다양한 단부 구조물의 개발에 있어서 압괴해석의 유용성을 확인하는데 그 목적이 있다.

• 국제물리치료학회지
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• 제3권1호
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• pp.345-355
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• 2012

This study purposed to examine the effect of low power laser on pain response and axonal regeneration. In order to prepare peripheral nerve injury models, we crushed the sciatic nerve of Sprague-Dawley rats and treated them with low power laser for 21 days. The rats were divided into 4 groups: normal group(n=10); control group(n=10) without any treatment after the induction of sciatic nerve crush injury; experimental group I(n=10) treated with low power laser(0.21$mJ/mm^2$) after the induction of sciatic nerve crush injury; and experimental group II(n=10) treated with low power laser(5.25$mJ/mm^2$) after the induction of sciatic nerve crush injury. We measured spontaneous pain behavior(paw withdrawal latency test) and mechanical allodynia(von Frey filament test) for evaluating pain behavioral response, and measured the sciatic function index for evaluating the functional recovery of peripheral nerve before the induction of sciatic nerve crush injury and on day 1, 7, 14 and 21 after the induction. After the experiment was completed, changes in the H & E stain and toluidine blue stain were examined histopathologically, and changes in MAG(myelin associated glycoprotein) and c-fos were examined immunohistologically. According to the results of this study, when low power laser was applied to rat models with sciatic nerve crush injury for 21 days and the results were examined through pain behavior evaluation and neurobehavioral, histopathological and immunohistological analyses, low power laser was found to affect pain response and axonal regeneration in both experimental group I and experimental group II. Moreover, the effect on pain response and axonal regeneration was more positive in experimental group I to which output 0.21$mJ/mm^2$ was applied than in experimental group II to which 5.25$mJ/mm^2$ was applied.

• 한국생산제조학회지
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• 제18권4호
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• pp.348-354
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• 2009

In order to reduce the risk of roll over crash, one of the greatest risk events, National Highway Traffic Safety Administration(NHTSA) issued Notice of Proposed Rulemaking(NPRM) enhancing the safety standard on roof crush resistance, FMVSS No. 216 and changing some part of the test procedure. According to this NPRM, the boundary Gross Vehicle Weight Rating(GVWR) of the vehicles applied by this standard is extended from 2,722kg(6000 lb) to 4,536 kg(10000 lb) and the applied test force is increased from 1.5 times to 2.5 times of Unloaded Vehicle Weight (UVW). Also the current limit on the amount of roof crush, 127mm(5 inch), is replaced with a new requirement of maintaining enough headroom without touching the head of a seated 50% male dummy. In this paper, we carried out the rollover crash test on some domestic cars and investigated their safety due to the KMVSS No. 92 and the enhanced safety standard, FMVSS No. 216, respectively. The result shows that most of them can satisfy the new standards but further tests will be necessary, especially for heavier cars.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 추계학술대회 논문집
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• pp.318-318
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• 2009

The door stiffness is one of the important factors side impact. Generally, the researches have been conducted on the assembled door module. This study is to analysis the side impact characteristics for automotives door module. The impact characteristics have been determined by door module side impact test machine. To determine the initial, intermediate and peak crush resistances use the plot of load versus displacement and obtain the integral of the applied load with respect to the crush distances specified below for each door tested. The initial crush resistance is the average force required to deform the door through the initial 6 inches of crush. The intermediate crush resistance is the average force required to deform the door through the initial 12 inches of crush. The peak crush resistance will be directly obtained from the plot of load versus displacement since it is the largest force required to deform the door through the entire 18 inches crush distance. The data are used to determine if a specific vehicle or item of automotives equipment meets the minimum performance requirements of the subject Federal Motor Vehicle Safety Standard(FMVSS). FMVSS Static 214, Side impact protection, specifies performance requirements for protection of occupants in side impact crashes.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2006년도 추계학술발표논문집
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• pp.179-184
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• 2006

• 펄프종이기술
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• 제41권5호
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• pp.8-14
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• 2009

Corrugated fiberboard is a widely used packaging material because of its high compressive strength and stiffness despite light weight. Corrugated fiberboards with microflutes with height $\leq$ 1.5 mm, such as E, F or G, have been developed. As microflutes have a different geometry from other conventional flutes, they may behave differently in testing and require a new testing method. Therefore, we evaluated the flat crush resistance of corrugated fiberboard with microflutes according to the ISO and TAPPI standard test methods. In addition, the effects of specimen area and platen compression rate were examined. The goal of this study was to identify an appropriate method for flat crush test (FCT) of corrugated fiberboard with microflutes. When a test piece with a standard area was subjected to the FCT in accordance with ISO and TAPPI methods, microflute corrugated fiberboard demonstrated a different load-displacement curve. An area of 20 $cm^2$ was determined to be the most appropriate for FCTof microflute corrugated fiberboard.

• 대한기계학회논문집
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• 제17권10호
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• pp.2555-2562
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• 1993

In this paper, the axial crush of the rectangular STS304 tube is analyzed using DYNA3D, and 10 models are tested under quasi-static load. The deformed shapes of analysis and test are present, and the analysis results are compared with the results of quasi-static test. This paper describes that free rotational boundary condition causes a very similar deformed shapes to expermental results, and using the elastic buclking modes as initial imperfecion shapes, the deformed shapes are very close to the experimental shapes.