• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2003년도 추계학술대회 논문집
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• pp.45-46
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• 2003

The x-ray micro-imaging technique was employed to measure the size and velocity of micro-bubbles moving in an opaque tube simultaneously. Phase contrast images were obtained at interfaces of micro-bubbles between water and air due to different refractive index. Micro-bubbles of $20\~120{\mu}m$ diameter moving upward in an opaque tube $(\phi=2.7mm)$ were tested. For two different working fluids of tap water and DI water, the measured velocity of micro-bubbles is roughly proportional to the square of bubble size.

• Journal of Advanced Marine Engineering and Technology
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• 제33권7호
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• pp.987-993
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• 2009

An experimental study is performed to investigate unsteady mixed convection in a horizontal channel with a heat source. Particle image velocimetry (PIV) with thermo-sensitive liquid crystal (TLC) tracers is used for visualization and analysis. This method allows simultaneous measurement of velocity and temperature fields at a given instant of time. Quantitative data of the temperature and velocity are obtained by applying the color-image processing to a visualized image, and neural network is applied to the color-to-temperature calibration. It is found that the periodic flow of mixed convection in a cavity appears at very low Reynolds numbers (Re<0.4), and the period decreases with increasing Reynolds numbers and increases with increasing aspect ratio.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(5)
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• pp.51-54
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• 2002

As digital systems continue to use components with faster edge rate and clock speeds, transmission of the digital information can take place many troubles. The increasing requirement for controlled impedance PCBs becomes both a critical success factor and a design challenge. Especially, the noise sources in digital system include the noise in power supply, ground and packaging due to simultaneous switching of signal, signal reflections and distortions on single and multiple transmission lines. This paper simulates the tracks controlled impedance with the test coupon. So, it can saves the design time and supports the economical PCB design.

• Journal of Advanced Marine Engineering and Technology
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• 제28권2호
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• pp.263-268
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• 2004

The characteristics of Diesel spray droplets, such as the velocity and the diameter were simultaneously measured by using an improved Interferometric Laser Imaging for Droplet Sizing method. The experiments were carried out using an accumulator-type unit injector system and a constant-volume vessel. Two dimensional cross-section photographs of sprays were also taken using a double-pulsed Nd- YAG laser sheet and a linear array CCD camera. As a result, interesting relations between the droplets diameter and the velocity were found.

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2000년도 추계학술대회 논문집
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• pp.304-305
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• 2000

대기 중 오존 농도의 증가가 빈번하여 짐에 따라 오존을 유발시키는 전구물질인 탄화수소의 관리에 대한 관심이 최근 크게 늘고 있다. 따라서 점점 많은 실험실에서 오존 전구물질에 대한 측정이 이루어지고 있거나 준비를 하고 있다. 오존 전구물질은 매우 많은 탄화수소로 구성되어 있어 복잡한 혼합성분으로 대기중에 존재하며, 농도 또한 매우 미량(low ppb)으로 낮아서 매우 까다로운 VOC 분석법을 요구한다. 그러므로 매우 많은 분석오차 요인이 측정과정에서 관여되어 있으며, 이로 인하여 측정 정확도의 관리, 유지가 어렵다. (중략)

• Journal of Advanced Marine Engineering and Technology
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• 제27권3호
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• pp.395-404
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• 2003

Quantitative data of the temperature and velocity were obtained simultaneously by using liquid crystal tracer. PIV(Particle Image Velocimety) based on a grey-level cross-correlation method was used for visualizing and analysis of the flow field. The temperature gradient was obtained by applying the color-image processing to a visualized image, and a neural-network a1gorithm was applied to the color-to-temperature calibration. This simultaneous measurement was applied to the Rayleigh-Bernard convection. This paper describes the method, and presents the quantitative visualization of Rayleigh-Bernard convection and the effect of aspect ratio and viscosity. Also the experimental results were compared with the numerical results.

• 대한기계학회논문집
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• 제10권5호
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• pp.601-610
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• 1986

본 연구에서는 음향학적 고찰로써 최근 디지를 처리기술의 발달에 따른 근접 한 2점의 음압으로 부터 테니스 라켓의 공기입자속도를 근사적으로 구하기 위하여 두 개의 마이크로폰을 이용하여 계산된 음향인텐시티는 구물의 오무드 해석법에 의해 구 해진 테니스 라켓의 동적 특성과 비교 검토함으로써 진동과 음의 발생기구를 구명하고 측정계의 비접촉에 의한 테니스 라켓의 동적 거동을 규명하였다.

• 한국통신학회논문지
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• 제12권3호
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• pp.200-203
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• 1987

방송위성을 이용하여 시각을 비교하는 방법을 제시하였다. 한국표준연구소와 일본전파연구소가 각기 보유하고 있는 원자시계의 시각비교 실험을 BS-2a을 이용하여 수행하였다. 그리고 본 실험에서는 미해군관측소(USNO)의 이동원자시계를 이용하여 시각비교 오차를 $0.1_mu$s이내로 보정하였다.

• 한국통신학회논문지
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• 제21권6호
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• pp.1596-1603
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• 1996

A single body type of fiber-optic current and voltae sensor using a rare earth doped YIG and a bismuth silicon oxide single crystsl is proposed, which is used for simultaneous measurement of the AC electric current and AC electric voltage over the trasmission lines. Experimental results showed that the fiber-optic current sensor has the maximum 7.5% error within the current range of 0A to 400A, and the fiber-optic voltage sensor has the maximum 0.87% error within the current range of 0V to 400V. The output waveforms of proposed fiber-optic sensor system has a good agreement with output waveforms of conductor current and voltage. Experimental results proved that the output of fiber-optic current sensor is not affected by the electric voltage applied to the fiber-optic voltage sensor, and also, that the output of fiber-optic voltage sensor is not affected by the electric current applied to the fiber-optic current sensor.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 춘계학술대회 논문집 기술교육전문연구회
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• pp.132-135
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• 2003

The use of the midnight power faces the crisis of the load peak-cut problem. Which appears at the simultaneous start of the midnight power system. We suggest a control method which uses the characteristics of boiler system. The system used that method consists of 6 heaters and are designed for the load distribution on each heater. Proposed method can take the balance of load during full time of midnight power supplied. The system is composed of measurement part and heater controller. Taking the data of the experience as a reason, the algorithm make the midnight power distribute. Experimental results show the validity of the method and the system proposed.