• 분석과학
• /
• 제14권6호
• /
• pp.486-493
• /
• 2001

본 연구는 SIMS를 이용한 bismuth titanate 박막의 깊이방향 분석에 있어서 mesh grid를 사용한 경우와 사용하지 않은 경우, offset voltage를 사용한 경우와 사용하지 않은 경우 등 분석조건에 따른 charging effect 그리고 검출한계의 특성을 검토하고자 하였다. 결과에 따르면 -40 V의 offset voltage를 사용하였을 경우는 charging effect의 감소는 물론 검출한계도 낮출 수 있었으나 mesh grid를 사용하였을 경우에는 charging effect는 다소 줄일 수 있었으나 반면 검출 한계는 오히려 높아졌다. O- 일차이온을 적용한 경우는 -40 V의 offset voltage를 사용하였을 때와 동일한 효과를 얻을 수 있었다.

• 한국기계가공학회지
• /
• 제20권2호
• /
• pp.1-7
• /
• 2021

A computer simulation was performed to study the effectiveness of temperature on the type of laser heat source in the context of the heterogeneous welding of aluminum and copper materials. Three different types of heat sources were used in the computer simulation: 1) Single Beam Straight Scan, 2) Single Beam Wobble Scan, and 3) Dual Beam Straight Scan. Among these sources, dual beam straight scan was found to be the most effective from the viewpoint of heat source control. Because the difference between the melting temperatures of copper and aluminum is approximately 400℃, a clear separation of heating temperature was required, and the dual beam straight scan provided superior controllability in this regard. When using the dual beam, the temperature of the 90:10 split was considerably easier to control than that of the 50:50 split. The optimal offset was calculated to be 4 mm off to the copper side, where the melting temperature and thermal conductivity were higher. In this manner, computer simulation was effectively used for determining the optimal laser beam hear source control without performing an actual laser welding experiment.

• 전자공학회논문지
• /
• 제52권2호
• /
• pp.83-88
• /
• 2015

본 논문에서는 $2mm{\times}2mm$ 크기를 가지며 빔의 위치가 다른 2가지 종류의 압저항형 가속도 센서를 설계하고 제작하여 감도 특성과 온도에 따른 옵셋 특성을 측정하고 비교하였다. 4빔 스프링 구조와 8빔 스프링 구조를 가지는 압저항형 가속도센서를 제작 하였으며, ANSYS 프로그램을 이용하여 공진주파수 특성과 스트레스 분포도를 분석하고 제작하였다. 제작된 가속도센서의 감도와 온도에 따른 옵셋 특성을 측정하고 서로 비교하였다. 감도는 4빔 스프링 구조가 $21.38{\mu}V/V/g$으로 더 우수한 특성을 보였으며 온도에 따른 옵셋 출력 전압은 4빔 스프링 구조가 $154.45ppm/^{\circ}C$으로 더 작게 변화하였다.

• Structural Engineering and Mechanics
• /
• 제30권1호
• /
• pp.21-36
• /
• 2008

The static response of a finite beam resting on a tensionless Pasternak foundation and subjected to a concentrated vertical load is assessed in this study. The concentrated vertical load may be applied at the center of the beam, or it may be offset from the center. The tensionless character of the foundation results in the creation of lift-off regions between the beam and the foundation. An analytical/ numerical solution is obtained from the governing equations of the contact and lift-off regions to determine the extent of the contact region. Although there is no nonlinear term in the equations, the problem shows a nonlinear character since the contact region is not known in advance. Due to that nonlinearity, the essentials of the problem (the coordinates of the lift-off points) are calculated numerically using the Newton-Raphson technique. The numerical results are presented in figures to illustrate the behaviours of the free-free and pinned-pinned beams under symmetric or asymmetric loading. The figures illustrate the effects of the shear foundation parameter and the symmetric and asymmetric loading options on the variation of the contact lengths and the displacement of the beam.

• Structural Engineering and Mechanics
• /
• 제57권6호
• /
• pp.989-1014
• /
• 2016

This paper deals with the analysis of the natural frequencies, mode shapes of an axially loaded beam system carrying ends consisting of non-concentrated tip masses and three spring-two mass sub-systems. The influence of system design and sub-system parameters on the combined system characteristics is the major part of this investigation. The effect of material properties, rotary inertia and shear deformation of the beam system is included. The end masses are elastically supported against rotation and translation at an offset point from the point of attachment. Sub-systems are attached to center of gravity eccentric points out of the beam span. The boundary conditions of the ordinary differential equation governing the lateral deflections and slope due to bending of the beam system including developed shear force frequency dependent terms, due to the sub.system suspension, have been formulated. Exact formulae for the modal frequencies and the modal shapes have been derived. Based on these formulae, detailed parametric studies are carried out. The geometrical and mechanical parameters of the system under study have been presented in non-dimensional analysis. The applied mathematical model is presented to cover wide range of mechanical, naval and structural engineering applications.

• Nuclear Engineering and Technology
• /
• 제52권9호
• /
• pp.2064-2071
• /
• 2020

For proton pencil beam scanning (PBS) technology, the accuracy of the dose distribution in a patient is sensitive to the properties of the incident beam. However, mechanical deformation of the proton therapy facility may occur, and this could be an important factor affecting the proton dose distribution in patients. In this paper, we investigated the effect of deformation on an SC200 proton facility's beam isocenter properties. First, mechanical deformation of the PBS nozzle, L-shape plate, and gantry were simulated using a Finite Element code, ANSYS. Then, the impact of the mechanical deformation on the beam's isocenter properties was evaluated using empirical formulas. In addition, we considered the simplest case that could affect the properties of the incident beam (i.e. if only the bending magnet (BG3) has an error in its mounting alignment), and the effect of the beam optics offset on the isocenter characteristics was evaluated. The results showed that the deformation of the beam position in the X and Y direction was less than 0.27 mm, which meets the structural design requirements. Compared to the mechanical deformation of the L-shape plate, the deformation of the gantry had more influence on the beam's isocenter properties. When the error in the mounting alignment of the BG3 is equal to or more than 0.3 mm, the beam deformation at the isocenter exceeds the maximum accepted deformation limits. Generally speaking, for the current design of the SC200 scanning beam delivery system, the effects of mechanical deformation meet the maximum accepted beam deformation limits. In order to further study the effect of the incident beam optics on the isocenter properties, a fine-scale Monte Carlo model including factors relating to the PBS nozzle and the BG3 should be developed in future research.

• 수산해양기술연구
• /
• 제36권3호
• /
• pp.195-201
• /
• 2000

계량어군탐지기를 이용하여 저서어를 대상으로 에코적분을 행하는 경우, 적분범위의 하한을 결정하기 위해 설정하는 해저기준이나 해저오프셋은, 저서어 자원량추정의 중요한 요인 중의 하나이다. 해저부근의 어군에코의 해석으로부터 해저기준의 결정방법과 최적 오프셋에 관하여 고찰한 결과, 다음과 같은 결과를 보였다. 1) 적분층의 폭을 5m로 하여, 적분범위를 1샘플링씩 해저방향으로 이동하면서, 해저부근의 S$\sub$a5m/의 변화를 본 결과, 해저부근의 어군에코를 적분하기 위해서는, 적분범위의 하한을 가능한 해저까지 접근시켜야 한다. 2) 에코레벨의 역치로서 해저검출을 행한 경우, 역치가 클수록 해저 검출 불능횟수가 증가하고, 작을수록 해저 오검출 횟수가 늘어 났다. 3) 에코레벨의 최대변화점을 해저기준으로 한 해저검출법은, 그 정도가 매우 높았으며, 나아가 에코레벨의 변동에 대해 아주 안정한 해저기준 알고리 즘으로 적합하였다. 4) 이 해저검출 알고리즘에 의하면, 최적해저오프셋은 해저 기준으로부터 0.4ms이내였고, 이것은 펄스파형과 해저지형에 대한 음향빔에 의존한다.

• ETRI Journal
• /
• 제34권6호
• /
• pp.946-949
• /
• 2012

We present the optimization of a birefringence-enhanced-waveguide (BWG)-based polarization beam splitter (PBS) in a Mach-Zehnder interferometer (MZI) configuration and analyze the structure-dependent or polarization-dependent phase difference, using a delay-line MZI (DL-MZI). We fabricate the DL-MZI using silica-based planar lightwave circuit technology and, using the DL-MZI, demonstrate the ability to optimize a PBS by measuring the birefringence of the BWG and structure-dependent phase offset.

• 한국안전학회지
• /
• 제13권1호
• /
• pp.3-12
• /
• 1998

On the stability of the cantilever beam subjected to a follower force at the free end, the influences of the translational spring and the moment of inertia of a tip mass at the free end have been studied by numerical methods. The centroid of a tip mass is offset from the free end of a Beam and is located along its extended axis to vary the value of moment of inertia of a tip mass. It is proved that as the constants of a spring supporting the free end are augmented, the critical flutter loads of the above system decrease, whereas they increase without a tip mass.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2002년도 하계종합학술대회 논문집(1)
• /
• pp.455-458
• /
• 2002

Design methods are presented for an X-band traveling-wave slot array realized on a rectangular waveguide. An array of 21 longitudinal slots is realized on the broad wall of a rectangular waveguide. The squint of the antenna main beam is adjusted using the element spacing and the waveguide broad wall dimension. The excitation of the array is controlled by the slot offset from the waveguide center line Multiple I-plane steps are placed around last slot elements so that the second-order beam due to tile reflected wave Is minimized A waveguide-to-coaxial adapter Is designed for feeding the array antenna from a coaxial system. Results of the design show an outstanding performance of the antenna 17.1 dB gain. 36"beam 1111, and -21 dB maximum sidelobe level.evel.