• 센서학회지
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• 제22권6호
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• pp.387-392
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• 2013

Camera rigs for shooting 3D video are classified as manual, motorized, or fully automatic. Even in an automatic camera rig, the process of Stereoscopic 3D (S3D) video capture is very complex and time-consuming. One of the key time-consuming operations is capturing the distance parameters, which are near distance, far distance, and convergence distance. Traditionally these distances are measured by tape measure or triangular indirect measurement methods. These two methods consume a long time for every scene in shot. In our study, a compact laser distance sensing system with long range distance sensitivity is developed. The system is small enough to be installed on top of a camera and the measuring accuracy is within 2% even at a range of 50 m. The shooting time of an automatic camera rig equipped with the laser distance sensing system can be reduced significantly to less than a minute.

• 한국정밀공학회지
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• 제12권8호
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• pp.73-85
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• 1995

The sensor system to measure the distance precisely from the center of the sensor system to the obstacle is needed to recognize the surrounding environments, and the sensor system is to be calibrated thoroughly to get the range information exactly. This study covers the calibration of the active range sensor which consists of camera and laser slit emitting device, and provides the equations to get the 3D range data. This can be possible by obtaining the extrinsic parameters of laser slit emitting device through image processing the slits measured during the constant distance intervals and the intrinsic parameters from the calibration of camera. The 3D range data equation derived from the simple geometric assumptions is proved to be applicable to the general cases using the calibration parameters. Also the exact 3D range data were obtained to the object from the real experiment.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.2170-2174
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• 2005

Selective Laser Sintering (SLS) is a useful rapid prototyping technique for the manufacture of three dimensional (3D) solid objects directly from a scanning data. A new approach called a Selective Multi-Laser Sintering (SMLS) system has been developed at Korea Institute Machinery & Materials (KIMM) as an industrial type SFFS. This SMLS machine is built with a frame, heaters, nitrogen supply part, laser system. This system uses the dual laser and 3D scanner made in $Solutionix^{TM}$ to improve the precision and speed for large objects. The three-dimensional solid objects are made of polyamide powder. The investigation on each part of SMLS system is performed to determine the proper theirs design and the effect of experimental parameters on making the 3D objects. The temperature of the system has a great influence on sintering the polymer. Because the stability of the powder temperature prevents the deformation of each layer, the controls of the temperature in both the system and the powders are very important during the process. Therefore, we simulated the temperature distribution of build room using the temperature analysis with ANSYS program. Selected radiant heater is used to raise temperature of powder to melting point temperature. The laser parameters such as scan spacing, scan speed, laser power and laser delay time affect the production the 3D objects too. The combination of the slow scan speed and the high laser power shows the good results without the layer curling. The work is under way to evaluate the effect of experimental parameters on process and to produce the various objects. We are going to experiment continuously to improve the size accuracy and surface roughness.

• 한국정밀공학회지
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• 제20권1호
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• pp.79-84
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• 2003

A light guide panel is an element of the LCD backlight module that is often used for the display of compact electronic devices. In this study, a laser marking system is proposed to fabricate light guide panel, which can replace other manufacturing methods such as silk printing, stamping, or v-cutting methods. The objective of this research is to evaluate the process parameters of the laser marking system. Light guide patterns were marked with a 50W $CO_2$ laser (CW) to understand the effects of average power and scanning speed on the geometry and quality of groove pattern. The width of the fabricated grooves increases with increasing laser power and decreasing scan speed. In order to analyze surface characteristics and optical properties (luminance, uniformity), SEM photography and BM7 (luminance measuring system) were used. As a result, the optimal conditions of the process parameters were determined.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.105.1-105.1
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• 2011

To enhance the performance of photovoltaic a-Si:H solar cells with a hybrid-type light absorbing structure of single crystal silicon nanoparticles (Si NPs) in a-Si:H matrix, single crystal Si NPs were produced by laser pyrolysis. The Si NPs were synthesized by $SiH_4$ gas decomposition using a $CO_2$ laser. The properties of Si NPs were controlled by process parameters such as $CO_2$ laser power, reactive gas pressure, and $H_2/SiH_4$ gas flows. The crystalline properties and sizes of Si NPs were analyzed by High Resolution Transmission Electron Microscopy (HRTEM). The sizes of Si NPs were controllable in the range of 5-15 nm in diameter and the effects of process parameters of laser pyrolysis were systematically investigated.

• Journal of Advanced Marine Engineering and Technology
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• 제32권4호
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• pp.570-577
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• 2008

Magnesium alloys are potentially useful as structural materials due to higher strength/weight ratio, heat conductivity and recyclability compared to other alloys. These alloys have attracted the interest of modern manufacturing such as the automobile, computer, communication and consumer electronic appliances industries. Hence welding techniques are required to be developed for these applications. Laser are known to be an excellent tool for them. This paper presents the laser weldability of AZ31 magnesium alloy with CW Nd:YAG laser. The low viscosity and surface tension of the melt pool make magnesium more difficult to weld than steel. As a result of this study, optimal process parameters could be obtained without weld defects. Also it was certain that cutting methods had influence on butt weldability.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 C
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• pp.1729-1731
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• 2003

Recently many solid-state laser systems were widely used in the medical applications. So it is necessary to study various optimal laser parameters for adopting new medical treatments. Alexandrite laser using switching mode power supply has designed and experimented to adjust a pulse repetition rate by PIC one-chip microprocessor. The fundamental results have been obtained during the first financial year in 2002. We will be able to find out the optimal hair removal characteristics by the repetitive experiments of Alexandrite laser as the parameters such as pulse repetition rate, pulse width, and pulse energy etc.

• Journal of Welding and Joining
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• 제29권6호
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• pp.82-87
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• 2011

In this study, we conducted laser welding by using remote scanner that is 5J32 aluminum alloy to observe the mechanical properties and optimize welding process parameters. As the control factors, laser incident angle, laser power and welding speed were set and as the result of weldablility, tensile shear tests were performed. ANOVA (Analysis of Variation) was also carried out to identify the influence of process variables on tensile shear strength. Strength estimation models were suggested using regression alnalysis and 2nd order polynomial model had the best estimation performance. In addition optimal welding condition was determined in terms with wedalility and productivity using objective function and fitness function. Final optimized welding condition was laser power was 4 kW, and welding speed was 4.6 m/min.

• 대한기계학회논문집A
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• 제34권11호
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• pp.1765-1771
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• 2010

MEMS 소자의 공정에서 가공된 비아 홀 품질은 소자의 성능에 가장 중요한 요소의 하나이다. Nd:$YVO_4$ 레이저로 가공한 비아 홀에 대한 레이저 미세가공의 일반적인 특징을 설명하고 그것의 측정에 대한 효율적인 최적화 방법을 소개한다. 본 논문의 최적화 방법은 직교다항식, 분산분석과 반응표면최적화는 최적 레이저 공정변수를 결정하고 주요 영향을 이해하는데 사용된다. 유의한 레이저 공정변수를 확인하고 이의 비아 홀 품질에 관한 영향을 고찰하였다. 레이저 공정변수의 최적 수준을 가지는 확인 실험은 최적화 방법의 유효성을 설명하기 위해 수행하였다.

• Journal of Welding and Joining
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• 제9권1호
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• pp.23-31
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• 1991

Laser beam weldability of zircaloy-4was investigated using a pulsed Nd: YAG laser of 200W average power. Mechanical properties of laser and GTA bead-on-plate welded zircaloy-4 test specimens were compared. The influence of plasma generated during laser welding was analyzed and optimum laser welding parameters were investigated.