• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.5
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• pp.921-925
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• 2007

This paper investigates the information related to the radiated sounds during treatment using the extracorporeal shock wave lothotriptor(ESWL). First, we observe the vibration of the objects from the radiated sounds and extract the information about the change of the peak frequency from the relation between the vibration and the radiated sounds. Next, we observe the change of the peak frequency according to the position of the focus and demonstrate that it is more difficult to vibrate objects exactly at the focal point than above or below the focus of the ESWL device. Lastly, we analyze the relation between the cavitation and the radiated sounds and examine the benefiting condition for the object fragmentation.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.5
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• pp.161-172
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• 2018

This paper proposed the robot vision control method to track a moving rigid body target using the vision system model that can actively control camera parameters even if the relative position between the camera and the robot and the focal length and posture of the camera change. The proposed robotic vision control scheme uses a batch method that uses all the vision data acquired from each moving point of the robot. To process all acquired data, this robot vision control scheme is divided into two cases. One is to give an equal weight for all acquired data, the other is to give weighting for the recent data acquired near the target. Finally, using the two proposed robot vision control schemes, experiments were performed to estimate the positions of a moving rigid body target whose spatial positions are unknown but only the vision data values are known. The efficiency of each control scheme is evaluated by comparing the accuracy through the experimental results of each control scheme.

• Steel and Composite Structures
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• v.47 no.3
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• pp.315-337
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• 2023

The steel structure is an assembly of individual structural members joined together by connections. The connections are the focal point to transfer the forces which is susceptible to damage easily. It is challenging to replace the affected connection parts after an earthquake. Hence, steel plates are utilised as a structural fuse that absorbs connection forces and fails first. The objective of the present research is to develop a beam-column end plate connection with single and dual fuse and study the effect of single fuse, dual fuse and combined action of fuse and damper. In this research, seismic resilient beam-column end plate connection is developed in the form of structural fuse. The novel connection consists of one main fuse was placed horizontally and secondary fuse was placed vertically over main fuse. The specimens are fabricated with the variation in number of fuse (single and dual) and position of fuse (beam flange top and bottom). From the fabricated ten specimens five specimens were loaded monotonically and five cyclically. The experimental results are compared with Finite Element Analysis results of Arunkumar and Umamaheswari (2022). The results are critically assessed in the aspect of moment-rotation behaviour, strain in connection components, connection stiffness, energy dissipation characteristics and ductility. While comparing the performance of total five specimens, the connection with fuse exhibited superior performance than the conventional connection. An equation is proposed for the moment of resistance of end-plate connection without and with structural fuse.

• Imaging Science in Dentistry
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• v.33 no.2
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• pp.79-83
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• 2003

Purpose : To assess the relationship between the direction of the indicating rod of the radiographic stent for ideal prosthetic design and the actual possible path of implant fixture placement when residual ridge resorption is considered. Materials and Methods: The study materials consisted of 326 implant sites (male 214 cases and female 112 cases) from a total of 106 patients (male 65 patients and female 41 patients) who desired implant prostheses. Computed tomography of patients were taken and reformatted using ToothPix/sup (R)/ software. Bony defects, bony sclerosis, the change of the direction of indicating rod, and root proximity of the adjacent teeth were examined on the CT-derived images. Results: The rate of the irregular crestal cortex was relatively high on premolar and molar area of maxilla. Mandibular molar area showed relatively high rate of focal sclerosis on the area of implant fixture insertion. The position of the indicating rods were relatively acceptable on the molar areas of both jaws. However, the position of the indicating rods should be shifted to buccal side with lingual rotation of the apical end on maxillary anterior teeth and premolar area. Conclusion: Clinically determined rod direction and position of the indicating rod for implant placement was not always acceptable for insertion according to the reformatted CT images. The pre-operative treatment plan for implant should be determined carefully, considering the state of the alveolar bone using the reformatted CT images.

• Journal of Korean Ophthalmic Optics Society
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• v.9 no.2
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• pp.473-480
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• 2004

Recently, they are interested in the relation between night's vehicle accidents of drivers and the dynamic visual acuity at home and aboard. So, in this research, we tried to design an optical system of the inspection equipment to measure the dynamic visual acuity. A optotype standard did to Landolt's ring with 45mm of diameter and 9mm of gap to maintain the visual acuity of 1.0 in the 30m distance. An optical structure of the inspection equipment was composed of the sequence of an observer, a plus refraction lens system, a minus refraction lens system, and an optotype that was arranged to have characteristics that the size of the first virtual image of the optotype made by the minus refraction lens system grows bigger gradually according to the optotype movement to near distance from far distance, and also the first virtual image moves to the principle plane from the focal point of the plus refraction lens system as the size of the first virtual image arranged to the inside of focal distance of plus refraction lens system grows bigger gradually. As doing these processes, we completed the optical system of which characteristic is that the position of the final second virtual image moves to 3m from 50m as the size of the second virtual image made by the plus refraction lens system maintains to be regular.

• Journal of Korean Ophthalmic Optics Society
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• v.18 no.4
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• pp.495-501
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• 2013

Purpose: This study was to develop golf range finder which could measure exact distance from golfer to flag by using telescope and biprism. Methods: Golf range finder was made that included telescope and biprism which could move in the telescope, and an accuracy of the range finder was analyzed in distance range 20~200 m. Results: An equation was made for measuring distance which was related at position of biprism, and we could measure distance successfully by using developed golf range finder. Biprism of 2 ${\Delta}$ was useful to measure in short distance but it had bad accuracy in long distance, and 0.5 ${\Delta}$ was more useful in long distance. Image got worse when the biprism approch to focal point of objective lens for measurement in long distance, so we developed multi-layer biprism to prevent the weak point. Conclusions: Image stabilization by biprism for measuring distance was confirmed. Even if hand was moving, the distance could be measured well by using biprism, and we could find that the induced equation for distance measurement was useful. We found that multi-layer biprism, which is was new developed, was more useful than general biprism when the biprism approched to focal point of objective lens for measurement in long distance.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1516-1519
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• 2004

A tele-operated robot should be used to maintain and inspect nuclear power plants to reduce the radiation exposure to the human operators. During an overhaul of the nuclear power plants in Korea, a ROV(Remotely Operated Vehicle) may enter a cold-leg connected to the reactor to examine the state of the thermal sleeve and it's position in the safety injection nozzle. To measure the positions of the thermal sleeve or scratches from the video images captured during the examination, the camera parameters should be identified. However, the focal length of the CCD camera could be increased to a close up of the target and the aspect ratio and the center of the image could also be varied with capturing devices. So, it is desired to self-calibrated the intrinsic parameters of the camera and capturing device with the video images captured during the examination. In the video image of the safety injection nozzle, two or more circular grooves around the nozzle are shown as ellipse contours. In this paper, we propose a camera self-calibration method using a single image containing two circular grooves which are the greatest circles of the cylindrical nozzle whose radius and distance are known.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.12
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• pp.1923-1932
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• 2013

In order to solve the problem of severely distorted images from a wide-angle camera, we propose a calibration method which corrects a radial distortion in wide-angle images by estimation and validation of camera model. First, we estimate a camera model consisting of intrinsic and extrinsic parameters from calibration patterns, where intrinsic parameters are the focal length, the principal point and so on, and extrinsic parameters are the relative position and orientation of calibration pattern from a camera. Next we validate the estimated camera model by re-extracting corner points by inversing the model to images. Finally we correct the distortion of the image using the validated camera model. We confirm that the proposed method can correct the distortion more than 80% by the calibration experiments using the lattice shaped pattern images captured from a general web camera and a wide-angle camera.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.4
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• pp.447-459
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• 2013

Many problems need to be solved before vision systems can actually be applied in industry, such as the precision of the kinematics model of the robot control algorithm based on visual information, active compensation of the camera's focal length and orientation during the movement of the robot, and understanding the mapping of the physical 3-D space into 2-D camera coordinates. An algorithm is proposed to enable robot to move actively even if the relative positions between the camera and the robot is unknown. To solve the correction problem, this study proposes vision system model with six camera parameters. To develop the robot vision control algorithm, the N-R and EKF methods are applied to the vision system model. Finally, the position accuracy and processing time of the two algorithms developed based based on the EKF and the N-R methods are compared experimentally by making the robot perform slender bar placement task.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.21 no.1
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• pp.33-39
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• 2011

The present study was carried out to investigate the potential acute toxicity of methylcyclohexane (MCH) by a single oral dose in female rats. The test chemical was administered once by gavage to female rats at dose levels 0, 1,250, 2,500, and 5,000 mg/kg. Mortalities, clinical findings, and body weight changes were monitored for the 14-day period following the administration. At the end of 14-day observation period, all animals were sacrificed and complete gross postmortem and histopathological examinations were performed. Treatment-related clinical signs, as evidenced by depression, soft feces, decreased locomotion activity, solid perineal region, crouching position, and anorexia were observed in all treatment groups in a dose-dependent manner. At the dose level of 5,000 mg/kg, decreased or suppressed body weight gain was found during the study period. At the scheduled necropsy, one case of congestion of the intestine and an increase in the weights of liver and kidney were observed in the 5,000 mg/kg group. Histopathological examinations exhibited an increased incidence of glomerular atrophy, congestion/hemorrhage, and focal degeneration/necrosis in the liver and an increased incidence of congestion, and inflammatory cell infiltration in the kidney. On the basis of the results, it was concluded that a single oral administration of MCH resulted in some adverse effects on clinical sign, body weight gain, and organ weight and histopathology in the liver and kidney in female rats. In the experimental conditions, the minimal lethal dose ($LD_{10}$) of MCH was greater than 5,000 mg/kg.