• Journal of the Korean Society for Railway
• /
• v.3 no.2
• /
• pp.43-50
• /
• 2000

The corrugated panels are the prime candidate structure for the floor, roof and wall of Korean high speed train. The equivalent continuum modeling approach panels can be used for the efficient design and evaluation of their structural characteristics. The equivalent continuum models, derived from the true complex corrugated panels, should have the same structural behavior as the original structures have. This paper briefly reviews three representative continuum modeling methods: the static analysis method and two plate-models based on modal analysis methods (MAM). These methods are evaluated through some numerical examples by comparing the natural frequencies and static deflections. It is observed that the plate-model based on Rayleigh-Ritz method seems to provide the best results when used in conjunction with the cantilever-type boundary conditions. The equivalent elastic constants of various corrugated panels, depending on the changes in their configurations, are tabulated for efficient use in structural design.

• Journal of Korean Society of Disaster and Security
• /
• v.14 no.1
• /
• pp.1-8
• /
• 2021

A corrugated pipe is widely used in firefighting equipment and sprinkler pipes because of its elasticity, which is less damaged by deformation and convenient facilities. However, the corrugated shape of the wall results in complex internal turbulent flow, and it is difficult to predict the pressure drop, which is an important design factor for pipe flow. The pressure drop in the corrugated tube is a function of the shape factors of the pipe wall, such as groove height, length, and pitch. Existing studies have only shown a study of pressure drop due to length changes in the case of D-shaped tubes with less than 5 pitch (P) and height (K) of the rectangular grooves in the tube. In this work, we conduct a numerical study of pressure drop for P/Ks with length and height changes of 2.8, 3.5 and 4.67 with Re Numbers of 55,000, 70,000 and 85,000. The pressure drop in the corrugated tube was interpreted to decrease with smaller P/K. We show that the pressure drop is affected by the change in the groove aspect ratio, and the increase in the height of the groove increases the recirculation area, and the larger the Reynolds number, the greater the pressure drop.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.37 no.10
• /
• pp.1297-1303
• /
• 2013

A nonlinear finite element analysis is performed to evaluate the sealing capability and stress of dust covers for the ball joint of an automotive steering system. The analysis is performed for two types of dust covers: wrinkle type and pot type. The assembly condition and operation condition are analyzed, and the maximum stress and contact normal stress at the ribs are evaluated. It is confirmed that the sealing capability of both types is fairly good, but the wrinkle type is better than the pot type in terms of the maximum stress.

• Proceedings of the KAIS Fall Conference
• /
• 2010.11b
• /
• pp.813-816
• /
• 2010

본 논문에서는 자동차 배기계를 구성하고 있는 Flexible Tube의 형상에 따른 응력 해석 결과를 이용하여 피로 해석을 하였다. 아울러 Flexible Tube의 변위량이 크게 발생하는 것을 고려하여 기하학적 비선형 해석을 실시하였으며 Flexible Tube의 변형량은 끝단에서 6mm의 변위가 발생하도록 하였다. 본 연구에서 얻어진 결과는 다음과 같다. (1) Tube의 반경이 증가하면 피로한계 응력반복수는 선형적으로 감소한다. (2) 본 연구에서 사용된 tube중 주름의 반경이 1.7mm일때 피로 수명이 가장 긴 것을 알 수 있다.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.11 no.4
• /
• pp.1192-1196
• /
• 2010

As the space for installation of automotive exhaust system is limited, the space should be optimized with relation to the endurance and shape of the system. Geometric nonlinear analysis was used and deflection of bellows was assumed 6mm. Obtained results are as follows; (1) The Von-Mises stress of bellows is increased with increase of thickness or radius of bellows linearly. (2) As the principal stress varies according to the radius of convolution, it is necessary to decide the optimal radius of convolution.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.34 no.9
• /
• pp.1167-1173
• /
• 2010

Forming of a silencer case was studied using a virtual tryout method. First, the appropriate blank shape was determined by cutting off the undeformed part of the rectangular blank. Then drawbeads were designed such that the formation of wrinkles on the shoulders and pipe connection can be prevented. Finally, the shape bead was designed such that fracture and formation of wrinkles around the pipe connection can be avoided. The prototype of the silencer case was manufactured in accordance with the conditions of the virtual tryout process. By comparing the formability of the prototype with the results of finite element analysis, it was found that the forming of the prototype agreed well with the results of analysis.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2008.11a
• /
• pp.69-70
• /
• 2008

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
• /
• 2010.10a
• /
• pp.308-311
• /
• 2010

본 연구에서는 유한요소해석을 통하여 나선 주름모양 소방용 파이프를 모델링하여 각 모델간의 발생응력과 변형량을 상호간에 비교 검토하여 강도 안전성이 우수한 배관시스템의 설계 최적화를 하기 위함이 연구의 목적이다.

• The Journal of the Convergence on Culture Technology
• /
• v.4 no.3
• /
• pp.197-207
• /
• 2018

The radish skin and radish greens (mucheong) are an edible part of the radish. But they are removed before eating the radish and used as a byproduct or an animal feed material because of their tough and rough texture. This study was conducted to investigate the effect of supercritical heat-treated radish-extract on UV-induced Hos: HRM-2 wrinkled mouse animal model on anti-aging wrinkles. Supercritical heat-treated radish-extract was applied on the back of seven-weeks old HRM-2 mice. The effect of HRE on skin thickness, elasticity and wrinkle formation of the mice was observed by using UVB lamp to induce melanogenesis and wrinkle formation. As the result, increased depth of wrinkles was observed in the negative control group in comparison to the normal group. In contrast, decreased depth of wrinkles was observed in the radish-extract-free group compared to the negative control group. In the study of the effect of radish-extract on wrinkle-formation related gene expression and protein what protein expression, MMP-2 and MMP-2 gene expression significantly increased in the negative control group compared to the normal group. The gene expression reduced independence to the mass of radish-extract treated. Similar to quantitative results of mRNA expression, the expression of MMP-2 protein increased as a result of UVB-irradiation. The MMP-2 expression was inhibited in dependence to the mass of radish-extract treated. In conclusion, the supercritical heat-treated radish-extract has an effect on improving skin wrinkles not only when it is applied to the skin but also when orally ingested. Thus, it can be effectively used as a composition to health functional products. Thereafter, we can also conclude that radish, a food that does not show any side-effects even upon long-term intake, can reduce wrinkle formation as well as improve skin elasticity when taken regularly for a long period.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.23 no.10
• /
• pp.928-934
• /
• 2013

In this paper, the vibration characteristics of the trapezoidally corrugated plate are investigated by the analytical method. The corrugated plate is widely used as the structural elements because of its high stiffness and light weight. Because the corrugated plate is flexible in the corrugation direction and stiff in the transverse direction, it is treated as an equivalent orthotropic plate to analyze the corrugated plate simply. This equivalent plate must include both extensional and flexural effect to obtain the precise solution. The effective extensional and flexural stiffness of the equivalent plate are derived to consider these effects in the analysis. To demonstrate the validity of the proposed approach, the comparison is made with the previously published results and ANSYS solutions. Some numerical results are presented to check the effect of the geometric properties.