• Journal of Welding and Joining
• /
• 제28권1호
• /
• pp.72-76
• /
• 2010

Irregular fluctuation of penetration depth in CW single mode fiber laser welding is analyzed statistically and chaotically. Among various chaos theories, one of the basic concept referred as Lyapunov exponent is applied to the analysis to quantify the irregularity of penetration. Especially, maximal Lyapunov exponent (MLE) is known as the representative value indicating chaotic degree of the system dynamics. MLE calculation method of experimental data is applied to longitudinal spiking defect in fiber laser weld. Laser power modulation is suggested as a remedy then the computed MLE value is compared to CW case. It is shown that the adoption of chaos theory, MLE computation, can be used as a measurement standard to prove the validity of the solutions to prevent the unexpected chaotic behavior of weld through this work.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2014년도 추계학술대회 논문집
• /
• pp.167-169
• /
• 2014

Spray combustion has been used in many industrial fields, for instance, such as diesel engines, gas turbines and industrial furnaces, and furthermore various measurement techniques have been applied to elucidate the phenomenon of spray combustion. In order to measure simultaneously the droplet velocity and the droplet size of spray, Phase Doppler Anemometry (PDA) was frequently used in spray combustion. However, the measurement error is occurred due to existence of flame, which is considered as influencing the precision of measurement. Therefore, the purpose of this study is experimentally to conduct the systematic evaluation on the measurement error when PDA measurement is applied to combustion field.

• 센서학회지
• /
• 제14권5호
• /
• pp.313-321
• /
• 2005

Spray combustion has been used in many industrial fields, for instance, such as diesel engines, gas turbines and industrial furnaces, and furthermore various measurement techniques have been applied to elucidate the phenomenon of spray combustion. In order to measure simultaneously the droplet velocity and the droplet size of spray, phase doppler anemometry (PDA) was frequently used in spray combustion. However, the measurement error is occurred due to existence of flame, which is considered as influencing the precision of measurement. Therefore, the purpose of this study is experimentally to conduct the systematic evaluation on the measurement error when PDA measurement is applied to combustion field.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2003년도 ICCAS
• /
• pp.1225-1230
• /
• 2003

In this study, Real-time estimation and compensation procedure are developed for the laser interferometer. This system is designed with homodyne quadrature-phase detection method using the Laser interferometer. The errors in this system are due to noise, disturbance and undefined model dynamics. DSP(Digital Signal Processor) is applied for real time compensation of these errors. This estimator and compensation is verified with measurement test.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2004년도 추계학술대회 논문집
• /
• pp.106-109
• /
• 2004

In this project, we have developed the eye-safe LRF system of 1.54 ${\mu}{\textrm}{m}$ wavelength using OPO. The maximum measured distance was 3.7km in outdoor experiment. We used Nd：YAG (1064nm) as a laser medium. It was applied BBO to construct the system. We also developed a time-counter for the range finder using a method of TOF (time of flight). The counter-clock used at the time counter was 320MHz making resolution within $\pm$1m. Start and stop signals were detected by two channel systems using PIN and APD. The LRF's repetition rate was 4 times per minute. The energy was measured to be over 9mJ. And, pulse-duration was 23ns. Resolution was $\pm$2m at the distance measurement using a target.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 2001년도 춘계학술대회 논문집(한국공작기계학회)
• /
• pp.137-142
• /
• 2001

Since recent production system becomes that of the small quantity, large volume with high quality production, accurate and high speed inspection system is required. In such situation, noncontact 3D measurement system which utilized CCD cameras is useful technique in terms of system cost, speed of data acquisition, measuring accuracy and application. However, it has low accuracy compared with contact 3D measurement system because of the camera distortion, non uniformity of laser distribution and so on. For those reasons, in this paper precision enhancement method is studied considering radial camera distortion, and laser distribution. A distortion correction method is applied even to the standard lens. The laser slit beam trajectory is determined by 3 method: based of the Gaussian function signal approximation, the median method, the center of gravity method and the peak point of the Gaussian function method.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2007년도 심포지엄 논문집 정보 및 제어부문
• /
• pp.373-376
• /
• 2007

As a part of automatic car parking, this paper have devised the distance measurement algorism using stereo vision system which measure between object and parking lot. In this simulation, laser pointer is used for detecting edge of designated object and real distance is measured by searching the position of laser pointer and measuring the distance. Which are 1 / 1.5 / 2 / 2.5 / 3m and adjusted correction had applied in order for use in car parking system.

• Corrosion Science and Technology
• /
• 제10권4호
• /
• pp.151-155
• /
• 2011

The iron oxide particles could be resulted from the corrosion of the circulating water system of a power plant. Because it may be one of the trouble materials which affect the power generation efficiency due to the deposition on steam generator tube and turbine blade, the continuous observation of its concentration is very important. The laser induced break-down detection (LIBD) technology was applied to monitor continuously the concentration of corrosion products with the detection limit of ppb level. The measurement system consists of a Nd:YAG pulsed laser, a polarizing beam splitter, a flow-type sample cell, an acoustic emission sensor, a high speed data acquisition board, a personal computer, etc.. The performance test results confirmed that this technology can be effective to monitor the corrosion product concentration of the circulating water system of a power plant.

• 비파괴검사학회지
• /
• 제32권4호
• /
• pp.388-392
• /
• 2012

본 연구에서는 표면파의 음향비선형 특성 측정을 위해 선 배열 레이저 빔을 이용하여 협대역의 표면파를 발생시키고 레이저 TWM(Two-Wave Mixing) 방식으로 수신하는 완전 비접촉 측정 방법이 도입되었다. 이 기술은 알루미늄 합금의 소성변형과 음향비선형 특성과의 상관성을 조사하는데 적용되었다. 그 결과, 재료의 소성변형에 따라 음향 비선형성이 비례적으로 증가하는 것으로 나타났으며, 이는 접촉식 PZT 탐촉자 수신 방법으로 측정한 결과와 동일한 경향이다.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
• /
• pp.570-571
• /
• 2005

In this paper, we introduced a LIF measurement method and summarized the theoretical side. When an altered wavelength of laser and electric power, lamp applied electric power, we measured the relative density of the metastable state in mercury after observing a laser induced fluorescence signal of 404.8nm and 546.2nm, and confirmed the horizontal distribution of plasma density in the discharge lamp. The results confirmed the resonance phenomenon regarding the energy level of atoms along a wavelength change, and also confirmed that the largest fluorescent signal in 436nm, and that the density of atoms in 546.2nm ($6^3S_1\rightarrow6^3P_2$) were larger than 404.8nm ($6^3S_1\rightarrow6^3P_1$). According to the increase of lamp applied electric power, plasma density increased, too. When increased with laser electric power, the L1F signal reached a saturation state in more than 2.6mJ. When partial plasma density distribution along a horizontal axis was measured using the laser induced fluorescence method, the density decreased by recombination away from the center.