• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년 영문 학술대회
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• pp.391-398
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• 2008

LES analysis was conducted with in-house CFD code to investigate the turbulence evolution and interaction due to turbulence ring and splash plate in the gas generator. Though chemical reaction was not accounted for, the results can be useful in determining the turbulence characteristics generated by ring and plate. The calculation results show that the installation of turbulence ring can introduce additional turbulences and improve turbulent mixing in the downstream flow. However, the addition of splash plate in the downstream of TR brings totally different shape of perturbation energy and enstrophy distribution for turbulent mixing. This enhancement can be done by the formation of the intensively strong vorticity production and mixing behind the plate. Pressure drop was found to be a reasonable level of about 1% or less of initial pressure in all calculation cases. Also, calculation results revealed that the variation of TR shape and intrusion length did not change the characteristics of turbulent mixing in the chamber. Even though the effect of installation location of splash plate on the turbulent mixing is not investigated yet, calculation results conclude the addition of splash plate leads to the increase in turbulent mixing with an acceptable pressure drop.

• 한국산학기술학회논문지
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• 제13권5호
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• pp.2009-2014
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• 2012

기어의 파인 블랭킹에서 기능면으로 사용되는 전단면(잇 면)을 최대한 확보하기 위하여 다이 롤 높이(die roll height)의 최소화는 매우 중요하다. 본 논문에서는 파인 블랭킹 금형의 핵심 설계 요소인 V-링 위치와 다이 챔퍼(die chamfer) 형상에 따라 기어의 다이 롤 높이 변화를 고찰하기 위하여 V-링 거리와 다이 챔퍼 형상이 다른 여러가지 다이 편 및 가이드 플레이트 편으로 구성된 파인 블랭킹 금형 세트를 제작하여 실험하였다. 각 실험으로부터 시편을 채취하여 다이 롤 높이를 측정 분석한 결과 파인 블랭킹 기어의 다이 롤 높이는 각 모듈에서 다이 챔퍼 각도가 증가함에 따라 증가하고 V-링 거리가 증가함에 따라 증가됨을 알 수 있었다.

• 대한기계학회논문집A
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• 제32권9호
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• pp.733-739
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• 2008

The X-ring is a elastomer with X-shaped cross-section used as a mechanical seal or gasket. Such a X-ring was equipped in a groove and compressed between two or more parts, acts as a seal on the interface. This study aims to detect contact stress and deformed shape of a X-shaped ring shell under various compressive contact conditions. A contact stress analysis was carried out by finite element analysis. The effect of compression rates and thickness design variable was analyzed. X-ring kept up the double seal until a compression rate of 20%. The maximum stresses of the X-ring was occurred at the top and bottom corner. The maximum contact stress of X-ring was rapidly increased according with the compression rate. The X-rings with thickness design variable from 1.3 mm to 1.5 mm had comparative low stress levels.

• 콘크리트학회논문집
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• 제22권6호
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• pp.817-824
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• 2010

약 콘크리트 격납구조물은 구조적 안전성이 뛰어나고 경제적이므로 원자력발전소 격납건물, LNG 저장탱크 등에 널리 사용되고 있다. 격납구조물 중 지붕 돔의 형태는 구조적 안전성, 물량 및 시공 난이도에 큰 영향을 미치므로 최적의 두께와 곡률을 도출하고자 하는 노력이 필요하다. 한편 일반적으로 PSC 구조로 설계되는 링빔은 이러한 돔을 지지하여 벽체의 변형을 최소화시키는 역할을 하며, 단면 크기와 더불어 프리스트레스 수준을 적절히 결정하는 것이 설계의 핵심이 된다. 이 연구에서는 축대칭 회전쉘의 막이론을 적용하여 본설계 시의 유한요소해석에 앞서 돔과 링빔의 초기 형상이나 프리스트레스 수준을 효율적으로 결정할 수 있는 기법을 제안하였다. 이러한 기법을 국내에서 시공된 격납구조물의 돔과 링빔에 적용하여 분석하고 단면 형상이나 프리스트레싱 설계에 대한 개선 방안을 고찰하였다.

• Structural Engineering and Mechanics
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• 제15권2호
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• pp.249-267
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• 2003

In this study, circular plates subjected to general type of loads and supported on a two-parameter elastic foundation are analysed. The stiffness, elastic bedding and soil shear effect matrices of a fully compatible ring sector plate element, developed by Saygun (1974), are obtained numerically assuming variable thickness of the element. Ring sector soil finite element is also defined to determine the deflection of the soil surface outside the domain of the plate in order to establish the interaction between the plate and the soil. According to Vallabhan and Das (1991) the elastic bedding (C) and shear parameters ($C_T$) of the foundation are expressed depending on the elastic constants ($E_s$, $V_s$) and the thickness of compressible soil layer ($H_s$) and they are calculated with a suitable iterative procedure. Using ring sector elements presented in this paper, permits the generalization of the loading and the boundary conditions of the soil outside the plate.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.1712-1713
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• 2011

Inkjet technology have many merits in plenty of industrial applications. However, deposited droplet has a very critical issue that is coffee ring effect, for the application to an industrial manufacturing process. To remove the coffee ring effect, the effect of thermal treatment conditions on shapes of inkjet printed silver patterns were investigated in various surface condition. The surface changes were characterized by the contact angle measurement. Droplets from a 50 ${\mu}m$ nozzle were printed on the substrate after optimizing the ejection of individual droplets. Ink with a high boiling point of main solvent results in coffee ring effect. This result implies that the dominant factor that determines the shape of droplet is the drying conditions of main solvent of silver nanoparticle colloidal ink. As a results, selecting a proper thermal treatment conditions is very crucial for better shapes of inkjet printed silver nanoparticle colloidal patterns.

• 한국정밀공학회지
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• 제18권9호
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• pp.140-146
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• 2001

Seals in a universal joint bearing are important components reinforcing lubrication performance by holding lubricant and preventing infiltration of dust, moisture, etc.. There is a great difference in seal performance according to seal shape and bonding position. Therefore, in this study, as for both the lip type seal and the O-ring type seal, FE analysis is conducted using Mooned-Rivlin Model. The results show that O-ring type seal does not have any effect of misalignment angle compared with lib type seal, which is more profitable.

• Advances in nano research
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• 제10권2호
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• pp.129-138
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• 2021

In present article, utilizing the Love shell theory with volume fraction laws for the cylindrical shells vibrations provides a governing equation for the distribution of material composition of material. Isotopic materials are the constituents of these rings. The position of a ring support has been taken along the radial direction. The Rayleigh-Ritz method with three different fraction laws gives birth to the shell frequency equation. Moreover, the effect of height- and length-to-radius ratio and angular speed is investigated. The results are depicted for circumferential wave number, length- and height-radius ratios with three laws. It is found that the backward and forward frequencies of exponential fraction law are sandwich between polynomial and trigonometric laws. It is examined that the backward and forward frequencies increase and decrease on increasing the ratio of height- and length-to-radius ratio. As the position of ring is enhanced for clamped simply supported and simply supported-simply supported boundary conditions, the frequencies go up. At mid-point, all the frequencies are higher and after that the frequencies decreases. The frequencies are same at initial and final stage and rust itself a bell shape. The shell is stabilized by ring supports to increase the stiffness and strength. Comparison is made for non-rotating and rotating cylindrical shell for the efficiency of the model. The results generated by computer software MATLAB.

• 콘크리트학회논문집
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• 제11권4호
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• pp.129-136
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• 1999

For the prediction of concrete-steel bond ability in reinforced concrete, many countries establish specifications for the pullout test. But these methods hardly to consider many parameters such as strength, shape, diameter and location of steel, concrete restrict condition by loading plate, strength of concrete and cover depth etc, and it is difficult to solve concentration and disturbance of stress. The purpose of this study is to propose a New Ring Test method which can be rational quantity evaluations of bond splitting mechanism. For this purpose, pullout test was carried out to assess the effect of several variables on bond splitting properties between reinforcing bar and concrete. Key variables are concrete compressive strength, concrete cover, bar diameter and rib spacing. Failure mode was examined and maximum bond stress-slip relationships were presented to show the effect of above variables. As the result, it appropriately expressed general characteristics of bond splitting mechanism, and it proved capability for standard test method.

• 한국항공우주학회지
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• 제36권12호
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• pp.1171-1179
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• 2008

난류고리와 스플래쉬 판에 의한 난류 혼합과 난류 생성에 관한 연구를 위하여 LES 해석이 가능한 CFD 코드를 개발하였으며 이를 사용하여 LES 해석을 수행하였다. 계산 결과에 의하면 난류고리는 유동장에 매우 강한 난류를 생성하여 후류에서 난류 혼합을 촉진하는 역할을 담당하는 것으로 밝혀졌다. 한편 난류고리 후류 방향으로 스플래쉬 판을 설치하면 난류고리만을 설치한 경우와 매우 다른 형태의 난류 에너지와 엔스트로피 생성을 관찰할 수 있었다. 이 경우의 난류혼합은 판 뒤에 생성되는 매우 강하며 집중적인 난류의 생성에 의하여 이루어지며 압력강하는 초기 압력의 1% 수준으로 매우 낮았다. 또한 계산결과에 의하면 난류고리의 형상이나 돌출 길이 변화는 생성되는 난류의 특성에 매우 커다란 영향을 미치지 못하였다. 난류 혼합을 가장 효과적으로 이룰 수 있는 판의 위치에 관한 연구 는 진행하지 못하였으나 지금까지 계산결과에 의하면 스플래쉬 판이 설치되었을 때 압력 강하도 낮은 수준이며 난류 혼합이 가장 효과적임을 알 수 있었다.