• Title/Summary/Keyword: Focal Position

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Reconstruction of extensive jaw defects induced by keratocystic odontogenic tumor via patient-customized devices

  • Park, Seok-Yong;Shin, Young-Jo;Kim, Chul-Hoon;Kim, Bok-Joo
    • Maxillofacial Plastic and Reconstructive Surgery
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    • v.37
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    • pp.37.1-37.4
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    • 2015
  • Keratocystic odontogenic tumors can occur in any area of the maxilla or mandible. According to their size, location, and relations with surrounding structures, they are treated by cyst enucleation or enucleation after either marsupialization or decompression. Enucleation is performed when cysts are not large and when only minor damage to adjacent anatomical structures is expected. Although marsupialization and decompression follow the same basic bone-regeneration principle, which is to say, by reducing the pressure within the cyst, the former leaves a large defect after healing due to the large fistula necessary to induce the conversion of the cyst-lining epithelia to oral epithelia; the latter leaves only a relatively small defect, because of the continuous washing carried out by means of a tube inserted into a small hole in the cyst. In the latter case too, a decompressor appropriate for the focal position is required, owing to the importance of maintaining the device and controlling for oral hygiene. We report herein decompression treatment with a patient-customized device for an extensive cyst in the anterior region of the mandible.

Heat Treatment Characteristics of Press Blanking Die by Using High Power Diode Laser (고출력 다이오드 레이저를 이용한 프레스 전단금형의 경화특성)

  • Hwang, Hyun-Tae;So, Sang-Woo;Hwang, Jae-Hyun;Kim, Jong-Do
    • Journal of the Korean Society for Heat Treatment
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    • v.23 no.5
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    • pp.257-262
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    • 2010
  • Recently, metal molding has become essential not only for automobile parts, but also mass production, and has greatly influenced production costs as well as the quality of products. Its surface has been treated by carburizing, nitriding and induction hardening, but these existing treatments cause considerable deformation and increase the expense of postprocessing after treatment; furthermore, these treatments cannot be easily applied to parts that requiring the hardening of only a certain section. This is because the treatment cannot heat the material homogeneously, nor can it heat all of it. Laser surface treatment was developed to overcome these disadvantages, and, when the laser beam is irradiated on the surface and laser speed is appropriate, the laser focal position is rapidly heated and the thermal energy of surface penetrates the material after irradiation, finally imbuing it with a new mechanical characteristic by the process of self-quenching. This research estimates the material characteristic after efficient and functional surface treatment using HPDL, which is more efficient than the existing CW Nd:YAG laser heat source.

Heat Treatment Characteristics of a Press Draw Mold by Using High Power Diode Laser (고출력 다이오드 레이저를 이용한 프레스 드로우금형의 열처리 특성)

  • Hwang, Hyun-Tae;So, Sang-Woo;Kim, Jung-Do;Kim, Young-Kuk;Kim, Byeong-Hun
    • Journal of the Korean Society for Heat Treatment
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    • v.22 no.6
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    • pp.339-344
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    • 2009
  • Recently, Laser surface treatment technologies have been used to improve wear charactenitics and fatigue resistance of metal molding. When the laser beam is irradiated on the surface and laser speed is appropriate, the laser focal position is rapidly heated and the thermal energy of surface penetrates the material after irradiation, finally imbuing it with a new mechanical characteristic by the process of self-quenching. This research estimates the material characteristic after efficient and functional surface treatment using HPDL, which is more efficient than the existing CW Nd:YAG laser heat source. To estimate this, microstructural changes and hardness characteristics of three parts (the surface treatment part, heat affect zone, and parental material) are observed with the change of laser beam speed and surface temperature. Moreover, the depth of the hardened area is observed with the change of the laser beam speed and temperature. From the results of the experiments, it has been shown that the maximum hardness is approximately 788Hv when the heat treatment temperature and the travel speed are $1150^{\circ}$ and 2 mm/sec, respectively.

System for Measuring the Welding Profile Using Vision and Structured Light (비전센서와 구조화빔을 이용한 용접 형상 측정 시스템)

  • Kim, Chang-Hyeon;Choe, Tae-Yong;Lee, Ju-Jang;Seo, Jeong;Park, Gyeong-Taek;Gang, Hui-Sin
    • Proceedings of the Korean Society of Laser Processing Conference
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    • 2005.11a
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    • pp.50-56
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    • 2005
  • The robot systems are widely used in the many industrial field as well as welding manufacturing. The essential tasks to operate the welding robot are the acquisition of the position and/or shape of the parent metal. For the seam tracking or the robot tracking, many kinds of contact and non-contact sensors are used. Recently, the vision is most popular. In this paper, the development of the system which measures the shape of the welding part is described. This system uses the line-type structured laser diode and the vision sensor. It includes the correction of radial distortion which is often found in the image taken by the camera with short focal length. The Direct Linear Transformation (DLT) method is used for the camera calibration. The three dimensional shape of the parent metal is obtained after simple linear transformation. Some demos are shown to describe the performance of the developed system.

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Prevention of Back Side Humping in Laser Welding of Al 5J32 Alloy by Using Laser Power Modulation (Al 5J32 합금의 레이저 용접에서 레이저출력 모듈레이션을 이용한 이면 험핑 비드의 안정화)

  • Ahn, Do-Chang;Kim, Cheol-Hee;Kim, Jae-Do
    • Journal of Welding and Joining
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    • v.29 no.4
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    • pp.80-84
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    • 2011
  • In the 5xxx series Al-Mg alloy, magnesium addition can increase the strength of aluminum alloy by solid solution strengthening but it has a relatively low melting and boiling temperature. During full -penetration laser welding of the Al-Mg alloys, its low boiling point and high vapor pressure brings about the spiky humping bead on the bottom side. Under back-side shielding, the spiking of back bead can be reduced but it restraints the process flexibility. In this study, a square pulse waveform modulation was employed to stabilize keyhole and back bead surface without back-side shielding. By using an experimental design, the bead shapes were evaluated for various process parameters such as the focal position, welding velocity and waveform parameters and the smooth back bead shape could be achieved.

The Developement of Secondary Optics Design Method for LED (LED 2차 광학 시스템의 설계법 개발)

  • Jung, Seung-Gyun;Seok, Dae-Il;Shin, Hwa-Young;Lee, Chang-Mo;Kim, Hoon
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.21 no.6
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    • pp.26-32
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    • 2007
  • Design methods of LED optic system includes point source assumption and imaginary focus approaches. However, these methods make significant error if the position of LED approachs that of optic system. This paper suggests a new design approach that LED is equally divided, light distribution of each division is predicted and confirmed through reverse tracing of light wave, and then each divided segment is separately designed, Using new design method, two kinds of example optic system were designed and light distribution and efficiency of the systems were evaluated.

Butt Welding Characteristics of Austenitic 304 Stainless Steel Using a Continuous Wave Nd:YAG Laser Beam (오스테나이트계 304 스테인리스강의 Nd:YAG 레이저 맞대기 용접특성)

  • Yoo, Young-Tae;Oh, Yong-Seok;Shin, Ho-Jun;Im, Kie-Gon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.28 no.2
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    • pp.165-173
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    • 2004
  • Laser beam welding is increasingly being used in welding of structural steels. The laser welding process is one of the most advanced manufacturing technologies owing to its high speed and deep penetration. The thermal cycles associated with laser welding are generally much faster than those involved in conventional arc welding processes, leading to a rather small weld zone. Experiments are performed for 304 stainless steel plates changing several process parameters such as laser power, welding speed, shielding gas flow rate, presence of surface pollution, with fixed or variable gap and misalignment between the similar and dissimilar plates, etc. The following conclusions can be drawn that laser power and welding speed have a pronounced effect on size and shape of the fusion zone. Increase in welding speed resulted in an increase in weld depth/ aspect ratio and hence a decrease in the fusion zone size. The penetration depth increased with the increase in laser power.

A Study on the Robot Vision Control Schemes of N-R and EKF Methods for Tracking the Moving Targets (이동 타겟 추적을 위한 N-R과 EKF방법의 로봇비젼제어기법에 관한 연구)

  • Hong, Sung-Mun;Jang, Wan-Shik;Kim, Jae-Meung
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.23 no.5
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    • pp.485-497
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    • 2014
  • This paper presents the robot vision control schemes based on the Newton-Raphson (N-R) and the Extended Kalman Filter (EKF) methods for the tracking of moving targets. The vision system model used in this study involves the six camera parameters. The difference is that refers to the uncertainty of the camera's orientation and focal length, and refers to the unknown relative position between the camera and the robot. Both N-R and EKF methods are employed towards the estimation of the six camera parameters. Based on the these six parameters estimated using three cameras, the robot's joint angles are computed with respect to the moving targets, using both N-R and EKF methods. The two robot vision control schemes are tested by tracking the moving target experimentally. Given the experimental results, the two robot control schemes are compared in order to evaluate their strengths and weaknesses.

A Study m Camera Calibration Using Artificial Neural Network (신경망을 이용한 카메라 보정에 관한 연구)

  • Jeon, Kyong-Pil;Woo, Dong-Min;Park, Dong-Chul
    • Proceedings of the KIEE Conference
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    • 1996.07b
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    • pp.1248-1250
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    • 1996
  • The objective of camera calibration is to obtain the correlation between camera image coordinate and 3-D real world coordinate. Most calibration methods are based on the camera model which consists of physical parameters of the camera like position, orientation, focal length, etc and in this case camera calibration means the process of computing those parameters. In this research, we suggest a new approach which must be very efficient because the artificial neural network(ANN) model implicitly contains all the physical parameters, some of which are very difficult to be estimated by the existing calibration methods. Implicit camera calibration which means the process of calibrating a camera without explicitly computing its physical parameters can be used for both 3-D measurement and generation of image coordinates. As training each calibration points having different height, we can find the perspective projection point. The point can be used for reconstruction 3-D real world coordinate having arbitrary height and image coordinate of arbitrary 3-D real world coordinate. Experimental comparison of our method with well-known Tsai's 2 stage method is made to verify the effectiveness of the proposed method.

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A Study on the Effect of Weighting Matrix of Robot Vision Control Algorithm in Robot Point Placement Task (점 배치 작업 시 제시된 로봇 비젼 제어알고리즘의 가중행렬의 영향에 관한 연구)

  • Son, Jae-Kyung;Jang, Wan-Shik;Sung, Yoon-Gyung
    • Journal of the Korean Society for Precision Engineering
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    • v.29 no.9
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    • pp.986-994
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    • 2012
  • This paper is concerned with the application of the vision control algorithm with weighting matrix in robot point placement task. The proposed vision control algorithm involves four models, which are the robot kinematic model, vision system model, the parameter estimation scheme and robot joint angle estimation scheme. This proposed algorithm is to make the robot move actively, even if relative position between camera and robot, and camera's focal length are unknown. The parameter estimation scheme and joint angle estimation scheme in this proposed algorithm have form of nonlinear equation. In particular, the joint angle estimation model includes several restrictive conditions. For this study, the weighting matrix which gave various weighting near the target was applied to the parameter estimation scheme. Then, this study is to investigate how this change of the weighting matrix will affect the presented vision control algorithm. Finally, the effect of the weighting matrix of robot vision control algorithm is demonstrated experimentally by performing the robot point placement.