• 제목/요약/키워드: BALANCE BEAM

검색결과 87건 처리시간 0.022초

AFM에서의 정량적 힘 측정을 위한 마이크로 캔틸레버의 강성 교정 (Accurate Determination of Spring Constants of Micro Cantilevers for Quantified Force Metrology in AFM)

  • 김민석;최재혁;김종호;박연규
    • 한국정밀공학회지
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    • 제24권6호
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    • pp.96-104
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    • 2007
  • Calibration of the spring constants of atomic force microscopy (AFM) cantilevers is one of the issues in biomechanics and nanomechanies for quantified force metrology at pieo- or nano Newton level. In this paper, we present an AFM cantilever calibration system: the Nano Force Calibrator (NFC), which consists of a precision balance and a one-dimensional stage. Three types of AFM cantilevers (contact and tapping mode) with different shapes (beam and V) and spring constants (42, 1, 0.06 N $m^{-1}$) are investigated using the NFC. The calibration results show that the NFC can calibrate the micro cantilevers ranging from 0.01 ${\sim}$ 100 N $m^{-1}$ with relative uncertainties of less than 2%.

Improvement on the Free Spanning Analysis of Offshore Pipelines

  • Jung, Jong-Heon;Park, Han-Suk
    • International Journal of Ocean Engineering and Technology Speciallssue:Selected Papers
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    • 제3권1호
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    • pp.49-55
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    • 2000
  • Improvement was made on the free span analysis of the offshore pipelines. The effect of axial force (both tension and compressive force) can be explicitly applied to the current design code. The closed form solutions of beam-column equation were derived for the typical boundary conditions. The solutions can be used to find the natural frequencies of the span using the energy balance concept. The results can be applied to the current design code and will result more realistic calculation of free span lengths of offshore pipelines.

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Analysis on lateral vibration characteristics of the deep-sea mining pipe

  • Xiao, Linjing;Liu, Qiang
    • Structural Engineering and Mechanics
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    • 제83권6호
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    • pp.835-851
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    • 2022
  • This paper analyzes the variation law of the pipe lateral vibration characteristics, it was treated as a beam model, and was dispersed into several subunits based on the FEM. The corresponding stiffness and mass matrix of the pipe was deduced by using Hermite interpolation function, and the overall dynamic balance equation was established. The lateral vibration under different pipe lengths, thicknesses and towing speeds are solved by integral method. The results show that the pipe vibration trend decreases first and then increases, and the vibration value at the ore bin is larger than that at the pump set, and the value at the top is the largest, and the least value location can change with the length increase. Increasing length and thickness can reduce lateral vibration value, while increasing speed can increase the value. Neither the thickness nor the towing speed will change the location where the least value occurs. The vibration intensity will increase with the decrease of pipe length and thickness and the increase of towing speed.

Delamination analysis of multilayered beams with non-linear stress relaxation behavior

  • Victor I., Rizov
    • Coupled systems mechanics
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    • 제11권6호
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    • pp.543-556
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    • 2022
  • Delamination of multilayered inhomogeneous beam that exhibits non-linear relaxation behavior is analyzed in the present paper. The layers are inhomogeneous in the thickness direction. The dealamination crack is located symmetrically with respect to the mid-span. The relaxation is treated by applying a non-linear stress-straintime constitutive relation. The material properties which are involved in the constitutive relation are distributed continuously along the thickness direction of the layer. The delamination is analyzed by applying the J-integral approach. A time-dependent solution to the J-integral that accounts for the non-linear relaxation behavior is derived. The delamination is studied also in terms of the time-dependent strain energy release rate. The balance of the energy is analyzed in order to obtain a non-linear time-dependent solution to the strain energy release rate. The fact that the strain energy release rate is identical with the J-integral value proves the correctness of the non-linear solutions derived in the present paper. The variation of the J-integral value with time due to the non-linear relaxation behavior is evaluated by applying the solution derived.

수영 훈련이 뇌허혈 유발 흰쥐의 해마 치아이랑에서 뇌신경생성과 기능적 능력에 미치는 영향 (The Effects of Swim Training on Neurogenesis in the Hippocampal Dentate Gyrus and Functional Ability After Focal Ischemic Stroke in Rats)

  • 김호성;김덕호;이정필;김영주;신영오;김상훈;권기욱;오재근
    • 한국전문물리치료학회지
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    • 제12권3호
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    • pp.11-21
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    • 2005
  • The present study was aimed at investigating the effect of swimming training on brain function after focal cerebral ischemia in rats. Therefore, this study was examined on neurogenesis in dentate gyrus of hippocampus using 5-bromo-2'-deoxyuridine (BrdU) to label proliferating cells and assessed the neurological response following focal cerebral ischemia in rats using neurological motor behavioral test. In an observer-blinded fashion, twenty male Sprague-Dawley (280~310 g, 7 weeks old) rats were divided into four groups: MCAO plus swimming group (ME, $n_1$=5), MCAO plus control group (MC, $n_2$=5), SHAM plus swimming group (SE, $n_3$=5), SHAM plus control group (SC, $n_4$=5). The results of this study were as follows: 1) The limb placing time before and after swimming in the ME group were significantly longer than the MC group (p<.05), the SE group were significantly longer than the SC group (p<.01). 2) The balance beam scores before and after swimming in the ME group was higher than the SE group, the MC group was higher than the SC group but was not significantly different (p>.001). 3) The foot fault index before and after swimming training in ME group was significantly lower (i.e., improved) than the MC group (p<.001) and the SE group (p<.001), the SE group was significantly lower (i.e., improved) than the SC group (p<.001). 4) The mean number of BrdU-positive cells in the dentate gyrus in the ME group was significantly higher than the MC group (p<.001) and the SE group (p<.01). The MC group and the SE group was significantly higher than the SC group (p<.001). 5) There was significantly correlation between limb placing time and number of BrdU-positive cells on swimming training, there was positive correlation (r=.807, p<.0001) and between foot fault index and BrdU-positive cells number, there was negative correlation (r=-.503, p<.05). However, between balance beam scores and BrdU-positive cells number, there was no correlation. In conclusion, the present study demonstrates that the role of swimming training improves behavioral motor function probably by enhancing cell proliferation in that hippocampus. This study provides a model for investigating the stroke rehabilitation that underlies neurogenesis and functional ability.

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EM Radioautographic Techniques에 관(關)한 연구(硏究) - Cork 방법(方法) - (An Improved Method for EM Radioautographic Techniques using Cork)

  • 김명국
    • Applied Microscopy
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    • 제10권1_2호
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    • pp.7-17
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    • 1980
  • Electron microscope radioautography introduced by Liquier-Milward (1956) is now used routinely in many laboratories. Most of the technical difficulties in specimen preparation have been overcome. This method is modified from loop method for improvement of EM radioautographic techniques. The advantages of this method are: 1. the use of single specimens on small corks and of a large wire loop, allows the experimenter to avoid the blemishes in the membrane; 2. the surfactant dioctyl sodium sulphosuccinate is added to diluted ILford L4, thus greatly prolonging the period of time over which good emulsion layers can be made; 3. corks can be handled in perspex holder which allows about 20 specimens to be developed simultaneously. The steps of the method comprise: 1. Cut ribbons of ultrathin sections of silver interference colour 2. Pick them up on formvar-coated 200 mesh grids 3. Prestaining of tissues 4. Coat the specimens with a thin layer of carbon by evaporation (30-60A) 5. Mount the specimens on corks (about 1cm apical diameter) using double-sided scotch tape 6. Emulsion coating; a. Take a 250m1 beaker, place it on the pan of a sliding weight balance and weigh it. Add 10 grams extra to the beam. Add pieces of ILford L4 emulsion to the beaker until the balance is swinging freely. Add the 20ml of distilled water that was previously measured out. b. Surfactant dioctyl sodium sulphosuccinate is added to diluted ILford L4. 7. Prepare a series of membranes of gelled emulsion with the wire loop and apply one to each cork-borne specimen. 8. Put the specimens away to expose by pushing the corks into short length of PVC tubing, each tube having a small hole in the side 9. Place the tubes in small boxes together with silica gel. 10. Exposure 11. Developer - Kodak Microdol X for 3 minutes 12. Fixer - A perspex holder can be manufactured which allows 20 specimens to be developed simultaneously. 12. Fixer - 30% sodium thiosulfate for 10 minutes 13. Examination with Siemens Elmiskop 1A electron microscope

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동력경운기 Plow System의 역학적 평행개선에 의한 연구 (Study on the Dynamic Balance of the Power-tiller Plow System)

  • 송현갑
    • Journal of Biosystems Engineering
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    • 제5권2호
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    • pp.26-39
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    • 1980
  • A study was investigated to find out the mechanical optimum conditions of power tiller-plow system on both paddy field and upland. Mathematical model was developed for the theoretical analysis of this system and the experimentation on the field was carried out with two different sizes of 5PS and 8PS power tiller equipped with rubber tire. 1) The relationship between the plowing depth and draft resistance of the power tiller-plow system was a quadratic function. 2) The minimum point of the specific draft resistance of the 5 PS plow was found at the smaller plowing depth than that of 8 PS plow, therefore we can find that the curved surface of 5PS plow bottom should be improved for the effective plowing operation. 3) As the improvement of the mechanical balance by the desirable change of the curved surface of plow bottom, the relative position of hitch point and dimension of plow beam would be realized, the 5 PS power tiller could be used to plow deeply (about 16-17cm). 4) The virtual acting point of the total draft resistance on the plow bottom approached to the land side as the plowing depth increased. 5) The resultant of vertical reaction force $R_2$ on the landside was increased with the plowing depth, while the vertical reaction force $R_1$ on the wheel was decreased as the slope angle of the body of power tiller increased. 6) For the effective plowing operations ; a) The slope angle of the body should be as small as possible. b) The diameter of the wheel should be as small possible. c) The horizontal and vertical distances $l_2, h_1$ between the wheel axis and plow bottom should be as large as possible. 7) To use the 5PS power tiller as the major unit of agricultural machinery, the curved surface of the 5 PS plower bottom and the mechanism of attachment between the power tiller and the plow should be changed as the indications of this study, and in addition to these, the new operation method of the field work should be developed.

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레이저빔을 이용한 솔더범프 적층 공정 (Solder Bump Deposition Using a Laser Beam)

  • 최원석;김재운;김종형;김주한
    • 대한기계학회논문집A
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    • 제36권1호
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    • pp.37-42
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    • 2012
  • LIFT(Laser-Induced-Forward-Transfer) 공정은 선택적으로 마이크로 크기의 물질을 이동시키는데 사용할 수 있는 레이저 공정이다. 본 연구에서 이 공정은 전자부품의 마이크로 시스템 패키징을 위한 솔더볼의 적층을 위해 적용되었다. 레이저 펄스에 의해 국부적으로 녹은 솔더 페이스트는 단단한 기저부분에 이동적층되었다. 솔더 크림층을 지닌 박판유리플레이트가 도우너 필름으로 사용되었고 1070nm 파장의 IR 레이저 펄스를 조사하여 리셉터에 마이크로 솔더를 이동적층하였다. 물질 및 에너지 평형 방정식 등이 솔더 페이스 드롭의 모양과 온도 분포를 분석하기 위해 적용되었다. 실제 실험에서 얻어진 이동적층된 솔더 범프는 30~40 ${\mu}m$ 의 직경과 50 ${\mu}m$ 의 두께를 가진 것으로 측정되었다. 본 공정의 한계 및 적용에 대해서도 논의한다.

인간 열환경 지수(HumanThermal Sensation)를 이용한 조경계획 및 디자인 방법 (Landscape Planning and Design Methods with Human Thermal Sensation)

  • 박수국
    • 한국조경학회지
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    • 제40권1호
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    • pp.1-11
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    • 2012
  • 이 연구는 인간 에너지 균형 모델에서 출발한 인간 열환경 지수 분석 방법을 이용하여 캐나다 BC주에 있는 나나이모시 상업지구안 좁은 길과 경상남도 창원시 중심상업지구에 있는 소공원을 연구 대상지로 2009년 여름철 열환경을 분석한 것이다. 기후 입력 자료는 기온, 상대습도, 풍속, 태양 및 지구 복사에너지이었으며, 그 결과 인간 열환경 지수에 가장 크게 영향을 미치는 요소들은 태양 직사광선, 건물시계지수 그리고 풍속이었다. 음지는 약간 더운 정도의 열환경을 조성하는 것으로 나타나 매우 덥게 나타난 양지에 비해 훨씬 좋은 열환경을 조성하는 것으로 나타났다. 나나이모 연구 대상지에 있는 좁은 길들은 주변의 넓은 장소들에 비해 주변 건축물에서 나오는 태양 반사광선과 지구 복사에너지들이 더 많이 영향을 미쳐 훨씬 덥게 나타났다. 낮은 풍속에 의해서 인체에서 방출되는 현열과 잠열의 양이 현저히 줄어듦으로서 더 더운 열환경이 조성되는 것으로 나타났다. 기후요소를 조경에 접목하기 위해서, 인간 열환경 지수 분석 방법을 이용하는 것은 열환경적으로 쾌적한 옥외 공간조성에 영향을 미칠 것이며, 도시 열섬 완화와 기후변화 연구에도 잘 이용될 수 있을 것이다.

Prediction of vibration and noise from steel/composite bridges based on receptance and statistical energy analysis

  • Liu, Quanmin;Liu, Linya;Chen, Huapeng;Zhou, Yunlai;Lei, Xiaoyan
    • Steel and Composite Structures
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    • 제37권3호
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    • pp.291-306
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    • 2020
  • The noise from the elevated lines of rail transit has become a growing problem. This paper presents a new method for the rapid prediction of the structure-borne noise from steel or composite bridges, based on the receptance and Statistical Energy Analysis (SEA), which is essential to the study of the generation mechanism and the design of a low-noise bridge. First, the vertical track-bridge coupled vibration equations in the frequency domain are constructed by simplifying the rail and the bridge as an infinite Timoshenko beam and a finite Euler-Bernoulli beam respectively. Second, all wheel/rail forces acting upon the track are computed by taking a moving wheel-rail roughness spectrum as the excitation to the train-track-bridge system. The displacements of rail and bridge are obtained by substituting wheel/rail forces into the track-bridge coupled vibration equations, and all spring forces on the bridge are calculated by multiplying the stiffness by the deformation of each spring. Then, the input power to the bridge in the SEA model is derived from spring forces and the bridge receptance. The vibration response of the bridge is derived from the solution to the power balance equations of the bridge, and then the structure-borne noise from the bridge is obtained. Finally, a tri-span continuous steel-concrete composite bridge is taken as a numerical example, and the theoretical calculations in terms of the vibration and noise induced by a passing train agree well with the field measurements, verifying the method. The influence of various factors on wheel/rail and spring forces is investigated to simplify the train-track-bridge interaction calculation for predicting the vibration and noise from steel or composite bridges.