• 한국자동차공학회논문집
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• 제20권5호
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• pp.65-70
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• 2012

Torque fluctuation of engine generate gear rattle noise of transmission and many researches have been studied to decrease rattle noise by adjusting clutch damper system. So design optimization of clutch system is very important to decrease rattle noise and need knowing clutch dynamic torque at real vehicle driving condition. This makes it possible to measure clutch dynamic torque by using a small-size magnetic sensor. We install a small-size magnetic sensor on the input shaft of the transmission and measure the relative angular displacement between clutch hub and disc plate. We can obtain the clutch torque correspond to the angular displacement in the clutch torsional characteristics test. The object of this research is to measure clutch dynamic torque on real vehicle condition. Therefore, Clutch dynamic torque is very useful for investigating operating range of clutch according to engine torque and predicting the damping performance of torsional vibration on the powertrain.

• 한국광학회지
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• 제12권4호
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• pp.300-304
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• 2001

압전소자에 전압을 가했을 때 길이가 늘어나며 휘어지는 것을 측정하고 보정하는 방법을 제시한다. 압전소자에 부착된 거울에서 반사되는 레이저빔의 각도 변화를 $0.36\mu$rad의 불확도로 측정하여 압전소자가 휘는 각도와 방향을 알수 있는 장치를 구성하였다. 압전소자의 전극을 세부분을 분할하고 축전기를 직렬 연결하여 하나의 전원으로도 각 전극에 인가되는 전압을 달리 조절할 수 있었다. 압전소자가 휘어지는 크기와 방향에 따라 각 전극에 연결되는 축전기의 용량을 달리함으로써 보정 전에 비해 휨을 6.3%로 줄일수 있었다. 휨이 보정된 압전소를 광자감쇠공동의 길이 변조에 이용하였을 때 압전소자가 휘기 때문에 야기되었던 감쇠시간 요동이 효과적으로 제거되는 것을 확인하였다.

• 한국자동차공학회논문집
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• 제6권6호
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• pp.210-217
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• 1998

This paper describes the method for detection of the misfired cylinder using the pressure fluctuations occurred in the exhaust system on an MPI gasoline engine. If misfire is occurred in the cylinder of the gasoline engine, the power of engine gets lost, the fuel consumption and the exhaust emission are increased and the vibration is caused by unsteady torque. Therefore early detection and correction of misfire play a very important role in the proper performance and the exhaust emission. This paper suggests method of misfire detection which affect engine performance. The method is a comparison of average pressure index during the displacement period. Experimental results showed that the method using the pressure fluctuations in the exhaust system is proven to be effective in the detection of misfire on gasoline engine regardless loads and revolutions of the engine. In addition, this method, using the pressure fluctuations in exhaust system is easier than other methods and is not a need of additional reconstruction of engine.

• 한국해양공학회지
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• 제21권3호
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• pp.46-51
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• 2007

A multi-purpose environmental monitoring system has been developed as a commercially available standard using the technique of hetero-core spliced fiber optic sensors, for the purposes of monitoring large-scale structures and preserving natural environments. The monitoring system has been tested and evaluated in a possible outdoor condition, in view of the full-scale operation at actual sites to be monitored. Additionally, the developed system in this work conveniently provides us with various options of sensor modules intended for monitoring such physical quantities as displacement, distortion, pressure, binary states, and liquid adhesion. Two channels of optical fiber line were monitored in each channel, three displacement sensor modules were connected in series, in order to examine the performance to a pseudo-cracking experiment in the outdoor situation and to clarify temperature influences an the system, in terms of the coupling of optical connectors and the OTDR stability. The results from the pseudo-cracking experiment agreed with the actual cracks, by means of calculation, based an the detected displacement values and their geometrical arrangement of the used sensor modules. The temperature change, ranging from 10 to $20^{\circ}C$ resulting from the 10-days free running operation, was found to influence the system stability of ${\pm}10{\mu}m$, primarily due to the coupling instability of the used optical connectors. It was found that fusion splicing, rather than the use of connectors, reduced the fluctuation dawn to ${\pm}2{\mu}m$. The specification and performance of various option modules have been demonstrated to show the capability of inspecting various physical quantities by use of the single system, which would be suitable for multi-purpose environmental monitoring.

• Structural Engineering and Mechanics
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• 제62권5호
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• pp.619-629
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• 2017

This paper focuses on the study of complete dynamic modeling and maximum dynamic load carrying capacity computation of N-flexible links and N-flexible joints mobile manipulator undergoing large deformation. Nonlinear dynamic analysis relies on the Timoshenko theory of beams. In order to model the system completely and precisely, structural and joint flexibility, nonlinear strain-displacement relationship, payload, and non-holonomic constraints will be considered to. A finite element solution method based on mixed method is applied to model the shear deformation. This procedure is considerably more involved than displacement based element and shear deformation can be readily included without inducing the shear locking in the element. Another goal of this paper is to present a computational procedure for determination of the maximum dynamic load of geometrically nonlinear manipulators with structural and joint flexibility. An effective measure named as Moment-Height Stability (MHS) measure is applied to consider the dynamic stability of a wheeled mobile manipulator. Simulations are performed for mobile base manipulator with two flexible links and joints. The results represent that dynamic stability constraint is sensitive when calculating the maximum carrying load. Furthermore, by changing the trajectory of end effector, allowable load also changes. The effect of torsional spring parameter on the joint deformation is investigated in a parametric sensitivity study. The findings show that, by the increase of torsional stiffness, the behavior of system approaches to a system with rigid joints and allowable load of robot is also enhanced. A comparison is also made between the results obtained from small and large deformation models. Fluctuation range in obtained figures for angular displacement of links and end effector path is bigger for large deformation model. Experimental results are also provided to validate the theoretical model and these have good agreement with the simulated results.

• Clinical and Experimental Pediatrics
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• 제49권11호
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• pp.1202-1210
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• 2006

목 적 : Tei 지수는 전반적인 심기능을 양적으로 쉽게 측정할 수 있는 장점이 있으나 심박동수, 전부하, 후부하에 영향을 받을 수 있으며 같은 심장 cycle에서 측정하기 어려운 단점이 제시되고 있다. 이에 반해 modified Tei 지수는 TDI을 이용하여 같은 cycle 내에서 측정 가능하기 때문에 기존의 Tei 지수의 단점을 보완할 수 있는 새로운 방법으로 제시되고 있다. 방 법 : 가와사키병의 급성기 환아 48명을 두 군(modified Tei 지수가 0.37 미만인 24명을 1군, modified Tei 지수가 0.37 이상인 24명을 2군), 그리고 열이 없는 정상 소아 30명을 대조군인 3군으로 나누어 연구를 시행하였다. 혈액 검사, TDI, 고식적인 심초음파를 시행하였다. 수축기 심근 속도, 초기 이완기(E') 심근 속도, 그리고 후기 이완기(A') 심근 속도와 조직 이동을 심저, 심중간부, 심첨에서 측정하였다. Ejection fraction(EF), Tei 지수, modified Tei 지수를 계산하였다. 결 과 : 백혈구수와 CRP는 2군에서 대조군에 비해 유의하게 높았다. 좌심실 기저부 수축기 심근 조직 이동, 초기 이완기 및 후기 이완기 심근 조직 이동이 2군에서 대조군에 비해 유의하게 감소하였다. Modified Tei 지수와 심실 기저부의 수축기 심근조직 이동(r=0.331), 초기 이완기(E') 심근 조직 이동(r=0.296), 그리고 후기 이완기(A') 심근 조직 이동(r=0.266)이 음의 상관관계를 보였다. Modified Tei 지수가 증가할수록 ESR(r=0.561)과 CRP(r=0.427)가 유의하게 증가하는 양의 상관관계가 보였다. EF과 Tei 지수는 정상이었다. 결 론 : 가와사키병에서 TDI를 이용한 modified Tei 지수는 EF이나 Tei 지수로 구별되지 않았던 심기능 이상을 발견하는데 매우 도움이 되는 유용한 지표로 생각된다.

• 한국가시화정보학회지
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• 제9권4호
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• pp.28-34
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• 2011

A volumetric gear pump is often used in extensive industrial applications to provide both high pressure and sufficiently high flow rate by physical displacement of finite volume of fluid with each revolution. Template mesh function in commercial CFD software, PumpLinx, by which 3-D meshes in the complex region between rotor and housing can be readily generated was employed for 3-D flow simulations. For cavitation analysis full cavitation model was included in 3-D simulations. The results showed high pulsation in pressure and flowrate which is implicated in pump vibration and noise. A model test for cavitation visualization was conducted and the results showed good qualitative agreement with numerical prediction.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.171-171
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• 2010

An innovative design of a floating-buoy wave energy converter (WEC) using hydrostatic transmission (HST), named HSTWEC, is presented in this paper. The system is designed to convert ocean wave fluctuation into electricity by using the HST circuit and an electric generator. Based on the floating-buoy concept, the wave forces the sub-buoy to move up and down. Consequently, the electric power can be obtained from the generator in both the moving directions of the sub-buoy through the HST circuit as shown in Fig. 1. In order to investigate the HSTWEC operations, a mathematical model of the system is indispensible. In addition, the method to control the HSTWEC, including: pump displacement control, tension adjustment control and ballast weight control, is also discussed in this paper. Finally, the design concept as well as simulation results indicated that this HSTWEC design is an effective solution and possible to fabricate for wave energy generation.

• 천문학회보
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• 제39권2호
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• pp.101.1-101.1
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• 2014

The fluctuation of VLBI visibility phase can be occurred, predominantly caused by the irregular distribution and motion of water vapor in the atmosphere at high frequencies (>1GHz). This radio-seeing effect shows up on filled-aperture telescopes as an anomalous refraction (AR). This can be shown as if the antenna pointing-offset increases, in other words the apparent displacement of radio sources from its nominal position happens. We carried out the single-dish observations on KVN sites in order to check the effect of AR from 2010 to 2014. Orion KL, U Her, and R Leo were observed with 1second sampling time at 22.235GHz and 43.122GHz simultaneously. Each source was observed with the tracking mode for 30 minutes per a source. We analyzed the structure function, power spectrum and Allan variance of the data according to a day and a night, a season and observatories. Finally, we can infer that the AR effect depends on the atmospheric environment, especially tropospheric turbulence.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2010년 춘계학술대회논문집
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• pp.83-85
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• 2010

A hydraulic gear pump is widely used in many industrial applications to provide both high pressure and high flow rate by physical displacement of finite volume of fluid with each revolution. In this study, two dimensional fluid-structure interaction simulation of gear pump flow was carried out to examine detailed complex flow patterns and structural stress distribution on rotors by using a commercial software ADINA. The effect of rotor clearance size on the flow characteristics, specially the temporal variation of velocity and pressure field, which is a main source of flow noise, also was investigated.