• 한국초전도ㆍ저온공학회논문지
• /
• 제3권2호
• /
• pp.69-76
• /
• 2001

Unsteady components of the second-order axial velocity and temperature within a tapered pulse tube were obtained by using a novel hybrid method of solution which combines an analytical solution with a numerical solution. The effects of operating frequency, taper angle and cold eng temperature on the unsteady components of the second-order axial velocity and temperature were shown. The unsteady component of the second-order mass flux had the amplitude of the same order as the steady component when the velocities at the ends of the pulse tube have only first-order components.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2007년도 춘계학술대회 논문집
• /
• pp.57-58
• /
• 2007

• 소성∙가공
• /
• 제21권3호
• /
• pp.160-163
• /
• 2012

In this paper, a new approach to finite element analysis for tube swaging is presented. An analysis model is developed with emphasis on the pusher that imposes back pressure in order to keep the workpiece from slipping along the die-workpiece interface especially when tapered dies are used. A rigid-plastic finite element method is employed. The approach is to simulate the tube swaging process and the results are compared quantitatively with predictions, showing close agreement with each other.

• 한국정밀공학회지
• /
• 제10권1호
• /
• pp.114-125
• /
• 1993

Thermoelastoplastic analysis of a typical device consisting of fixed tube and movable case having an inital clearance in between, which is subjected to pressure and thermal load, has been carried out to examine the cause of malfunction mainly at high temperature condition, and to improve the design. Stresses, deformed shape, interface state and their effects on normal function of case are discussed by using finite element method. The extraction energy can be remarkably reduced by changing the configuration of tube from the present design (Parallel type) to the improved design (Tapered type). This effect has been proved by sustained cyclic function test.

• 대한토목학회논문집
• /
• 제5권2호
• /
• pp.35-39
• /
• 1985

얇은 관형단면(管形斷面)을 갖는 선형변단면부재(線型變斷面部材)를 포함(包含)하는 구조물(構造物)의 해석(解析)에 이용(利用)되는 강도(剛度)매트릭스를 정적분(定積分)을 사용(使用)하여 유도(誘導)하였다. "정형적분식(整形績分式)"으로 표현(表現)된 매트릭스 요소(要素)에 수치적(數値的) 불안정(不安定)을 주는 요인(要因)을 발견(發見)하고, 그 오차(誤差)를 살펴 보기 위하여 정적분(定積分)의 급수해(級數解)도 구(求)하였다. "정형적분식(整形績分式)"으로 규현(表現)된 정적분(定積分)의 사용범위(使用範圍)는 상대경사(相對傾斜)에 의(依)하여 규정(規定)하였다.

• 대한기계학회논문집B
• /
• 제24권4호
• /
• pp.608-613
• /
• 2000

The present study has proposed a novel aerosol CVD utilizing an internal jet in the conventional MCVD reactor for the purpose of enhancing the deposition efficiency(and rate) and the uniformity of deposited film. The use of impingement of high temperature jet through a thin inner tube ensures the reduction of non-uniform particle deposition zone as well as higher thermophoretic particle deposition. It is shown that significant improvements have been achieved for both aspects of deposition efficiency and uniformity. As jet temperatures increase, the tapered length is reduced and deposition efficiency is significantly increased.

• 대한기계학회논문집A
• /
• 제30권12호
• /
• pp.1618-1625
• /
• 2006

During the last two decades, several guidelines have been developed and used for assessing the integrity of a defective steam generator (SG) tube that is generally caused by stress corrosion cracking or wall-thinning phenomenon. However, as some of SG tubes are also failed due to fretting and so on, alternative failure estimation schemes are required for relevant defects. In this paper, parametric three-dimensional finite element (FE) analyses are carried out under internal pressure condition to simulate the failure behavior of SG tubes with different defect configurations; elliptical wear, tapered and flat wear type defects. Maximum pressures based on material strengths are obtained from more than a hundred FE results to predict the failure of SG tube. After investigating the effect of key parameters such as defect depth, defect length and wrap angle, simplified failure estimation equations are proposed in relation to the equivalent stress at the deepest point in wear region. Comparison of failure pressures predicted by the proposed estimation scheme with corresponding burst test data showed a good agreement.

• Journal of Advanced Marine Engineering and Technology
• /
• 제9권4호
• /
• pp.339-347
• /
• 1985

Precise measurement of flowrate is considered as an important measuring factor in mechanical and chemical experiment. Although there are many methods to measure flowrate, Float type flowmeter is widely used because of its easy attachment to piping and high measuring precision. To design the precise float type flowmeter, much design information such as tapered-tube dimensions, float size, float shape and float material is required. In this paper, fundamental design theory for float type flowmeter according to the given flowrate range is suggested and compensation coefficients of volumetric and weight flowrate for water, R-113 and air are calculated.

• 대한기계학회논문집
• /
• 제18권11호
• /
• pp.3057-3065
• /
• 1994

An experimental study has been made for heat transfer and particle deposition during the Modified Chemical Vapor Deposition process which is currently utilized to manufacture high quality optical waveguides. The distributions of tube wall temperatures, rates and efficiencies of particle deposition were measured. Results indicate that the temperature distributions of the tube wall in the axial direction yield the quasi-steady form in which temperature distributions fit in one curve if the relative distance from the moving torch is used as an axial coordinate. Due to the repeated heatings from the traversing torch, the wall temperatures are shown to reach the minimum ahead of torch and it is shown that the two torch formulation suggested by Park and Choi is valid to predict this minimum temperature. Measured wall temperatures, particle deposition efficiencies and tapered entry length are compared with the previous modelling results and shown to be in agreement.

• Composites Research
• /
• 제14권6호
• /
• pp.32-37
• /
• 2001

광섬유 센서의 복굴절 현상을 방지하기 위해 리코팅이나 유리 튜브를 이용하여 보호하는 방법이 있다. 하지만, 이와 같은 처리를 하였을 경우 센서의 변형률 전달성에 대한 검증이 아직 이루어지지 알았다. 본 연구에서는 세가지 형태(재킷이 벗겨진, 리코팅을 한, 유리 튜브로 보호한)의 광섬유 브래그 격자 센서를 제작하여 그라파이트/에폭시 복합재료 적층시편의 인장 실험을 통해 변형률 전달성을 검증하였다. 광섬유 센서는 삽입 적용하였고 표면에 부탁한 변형률 게이지와 값을 비교하였다. 그리고 변형률 구배가 존재하는 경사진 알루미늄 시편의 인장 실험을 통해 각 센서의 신호 특성을 비교하였다.