• Journal of Mechanical Science and Technology
• /
• 제19권9호
• /
• pp.1731-1741
• /
• 2005

In this paper, we studied about the effect of the open crack and a tip mass on the dynamic behavior of a cantilever pipe conveying fluid with a moving mass. The equation of motion is derived by using Lagrange's equation and analyzed by numerical method. The cantilever pipe is modelled by the Euler-Bernoulli beam theory. The crack section is represented by a local flexibility matrix connecting two undamaged pipe segments. The influences of the crack, the moving mass, the tip mass and its moment of inertia, the velocity of fluid, and the coupling of these factors on the vibration mode, the frequency, and the tip-displacement of the cantilever pipe are analytically clarified.

• 한국정밀공학회지
• /
• 제8권4호
• /
• pp.107-117
• /
• 1991

The dynamic stability problem of nonconservative system is one of the important problems. In this study, flexible missile with mass variation is regarded as a free Timoshenko beam subjected to a controlled follower force. The stability was studied numerically through the finite element method. Through the study, the obtained results are as follows: [1] Without force direction control (1) In the case of no mass reduction, the existence of concentrated mass increases critical follower force. (2) Mass reduction rate of the beam slightly effects on the change of critical follower force. [2] With force direction control (1) Shear deformation parameter S contributes insignificantly to the force at instability when $S{\geq}10^4$. (2) With mass variation, increase of concentrated mass increases critical follower force at instbility. (3) The type of promary instability is determined by the sensor location.

• 한국식생활문화학회지
• /
• 제30권1호
• /
• pp.54-63
• /
• 2015

This study was conducted to examine the effects of local food value perception on purchasing and experience in consumers. ${\chi}^2$-test, ANOVA, and linear regression analysis were conducted. The findings are summarized as follows: The most common place for buying agricultural products was 'hypermarkets' (41.7%), and the most important factor for purchasing local food was 'local government's certification products' (23.7%). The most important value recognition item for local food was 'I think that local food is a high-quality agricultural products'. (3.74 points), followed by 'I think that local food have a value of respect for customers' (3.61 points) and 'I have a faith for the local food'. (3.61 points) in that order. The main tourism experience activity was 'food experience' (49.0%), and information source of local food experience tourism was 'mass media (TV, newspapers, etc.)' (37.3%). As age increased, experience of local food also increased. The most effectual value recognition item for purchasing local food was 'I think that local food have a value of respect for customers'. The most effectual value recognition item for increasing intake experience of local food was 'I think that the local food is high-quality agricultural products'.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
• /
• pp.105.1-105.1
• /
• 2016

Many of the complex materials developed today derive their unique properties from the presence of multiple phases or from local variations in elemental concentration. Simply performing analysis of the bulk materials is not sufficient to achieve a true understanding of their physical and chemical natures. Secondary ion mass spectrometer (SIMS) has met with a great deal of success in material characterization. The basis of SIMS is the use of a focused ion beam to erode sample atoms from the selected region. The atoms undergo a charge exchange with their local environment, resulting in their conversion to positive and negative secondary ions. The mass spectrometric analysis of these secondary ions is a robust method capable of identifying elemental distribution from hydrogen to uranium with detectability of the parts per million (ppm) or parts per billion (ppb) in atomic range. Nano secondary ion mass spectrometer (Nano SIMS, Cameca Nano-SIMS 50) equipped with the reactive ion such as a cesium gun and duoplasmatron gun has a spatial resolution of 50 nm which is much smaller than other SIMS. Therefore, Nano SIMS is a very valuable tool to map the spatial distribution of elements on the surface of various materials In this talk, the surface imaging applications of Nano SIMS in KBSI will be presented.

• 대한기계학회논문집B
• /
• 제22권4호
• /
• pp.530-541
• /
• 1998

Heat transfer augmentation in a rib-roughened duct is affected by the rib configurations, such as rib height, angle of attack, shape, rib to rib pitch, and aspect ratio of a duct. These have been the main subjects in studying the average heat transfer and the friction loss of the fully developed flow. Investigating distributions of local heat transfer coefficients and flow patterns in a duct with the rib turbulators is necessary to find the characteristics of heat transfer augmentation and to decide the optimal configurations of ribs. In the present study the numerical analyses and the mass transfer experiments are performed to understand the flow through a rib roughened duct and the heat transfer characteristics with various angles of attack of ribs. A pair of counter-rotating secondary flow in a duct has a main effect on the lateral distributions of local mass transfer coefficients. Downwash of the rotating secondary flow, reattachment of main flow between ribs and the vortices near ribs and wall enhanced the mass transfer locally up to 8 times of that in case of the duct without ribs.

• Advances in nano research
• /
• 제9권4호
• /
• pp.221-235
• /
• 2020

The following composition establishes a nonlocal strain gradient plate model that is essentially related to mass sensors laying on Winkler-Pasternak medium for the vibrational analysis from graphene sheets. To achieve a seemingly accurate study of graphene sheets, the posited theorem actually accommodates two parameters of scale in relation to the gradient of the strain as well as non-local results. Model graphene sheets are known to have double variant shear deformation plate theory without factors from shear correction. By using the principle of Hamilton, to acquire the governing equations of a non-local strain gradient graphene layer on an elastic substrate, Galerkin's method is therefore used to explicate the equations that govern various partition conditions. The influence of diverse factors like the magnetic field as well as the elastic foundation on graphene sheet's vibration characteristics, the number of nanoparticles, nonlocal parameter, nanoparticle mass as well as the length scale parameter had been evaluated.

• 대한기계학회논문집
• /
• 제19권4호
• /
• pp.1071-1082
• /
• 1995

Numerical analyses have been performed to obtain the absorption heat and mass transfer coefficients and the absorption mass flux from a falling film of the LiBr aqueous solution which is cooled by cooling air. Heat flux at the wall is specified in terms of the heat transfer coefficient of cooling air and the cooling air temperature. Effects of operating conditions, such as the heat transfer coefficient, the cooling air temperature, the system pressure and the solution inlet concentration have been investigated in view of the local absorption mass flux and the total mass transfer rate. Effects of film thickness and film Reynolds number on the heat and mass transfer coefficients have been also estimated. Analyses for the constant wall temperature condition have been also carried out to examine the reliability of present numerical method by comparing with previous investigations.

• 천문학회지
• /
• 제25권1호
• /
• pp.11-21
• /
• 1992

Applying mass model to disk galaxy NGC 300, since the observed rotation curve of NGC 300 is flatter than Toomre's mass model n = 1, two cases are used; obtaining parameters $a^n$ and $b^n$ from the polynomial fitting of the observed rotation curve (case A) and from the least square fitting between the observed rotation curve and model rotation curve (case B). In any case, n bas a fixed value of 1. Brandt's mass model is also discussed. which has a shape parameter n = 1.4. Calculated total mass and total mass to luminosity ratio are $3.3{\times}10^{10}M_{\odot}$, l2.1 for case A and $2.8{\times}10^{10}M_{\odot}$, 10.3 for case B. In case of Brandt's model, the values are $4.2{\times}10^{10}M_{\odot}$ and 15.4. The rise in the local mass to luminosity ratio in the outer part of NGC 300 implies existence of massive halo. Other dynamical properties are also discussed.

• International Journal of Precision Engineering and Manufacturing
• /
• 제9권3호
• /
• pp.33-39
• /
• 2008

The effects of a double crack and tip masses on the dynamic behavior of cantilever beams with a moving mass are studied using numerical methods. The cantilever beams are modeled by applying Euler-Bernoulli beam theory. The cracked sections are represented by a local flexibility matrix connecting three undamaged beam segments. The influences of the crack, moving mass, and tip mass, and the coupling of these factors on the vibration mode and the frequencies of the double-cracked cantilever beams are determined analytically. The methodology provides a basis for analyzing the dynamic behavior of a beam with an arbitrary number of cracks and a moving mass.

• 디자인학연구
• /
• 제18권2호
• /
• pp.303-314
• /
• 2005

본 연구는 강원도 인제군 향토축제의 활성화와 목공예산업의 동반 육성을 궁극적인 목적으로 하고 있으며, 이에 따라 'DESIGN HOSPITAL' 의 운영, '퍼즐(Puzzle)식 레이저 목재상감 기법'을 접목시킨 모듈화 생산공정 구축을 통한 지역고유성을 상징하는 목공예 관광기념품의 디자인 개발 및 축제와 연계한 생산 유통계획을 수립하여 제시하였다. 연구방법으로서 문화컨텐츠화를 목표로 추진된 타 시 군 지역축제의 관광기념품 개발 성공사례를 분석, 벤치마킹을 통해 인제군의 여건에 적합한 관광문화상품 개발계획을 수립하고자 하였다. 연구결과는 다음과 같다. 우선, 가칭 '문화상품 DESIGN HOSPITAL'의 운용으로 생산업체에 디자인 아웃소싱을 실시, 디자인 전문 브레인을 무상 공급하여 인력난 해소 및 단기간의 제품개발 능력을 확보할 수 있도록 하였다. 이를 토대로 첨단 디지털 제작기술의 도입 및 활용에 의한 대량맞춤(Mass Customization) 생산을 적용하여 축제의 특성에 적합한 문화상품 생산유연성을 확보 가능토록 했으며, 차별화 된 마케팅 전략, 관광기념품 공모전을 통한 제품의 디자인파워 제고, 캐릭터 개발 등의 세부계획 실천으로 관내 목공예업체의 수익성 제고와 지역 문화/경제의 발전 가능성을 동시에 획득할 수 있도록 최적안을 제시하고자 하였다.