• The Journal of Korea Robotics Society
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• v.12 no.4
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• pp.385-394
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• 2017

Side scanning sonar (SSS) provides valuable information for robot navigation. However using the side scanning sonar images in the navigation was not fully studied. In this paper, we use range data, and side scanning sonar images from UnderWater Simulator (UWSim) and propose measurement models in a feature based simultaneous localization and mapping (SLAM) framework. The range data is obtained by echosounder and sidescanning sonar images from side scan sonar module for UWSim. For the feature, we used the A-KAZE feature for the SSS image matching and adjusting the relative robot pose by SSS bundle adjustment (BA) with Ceres solver. We use BA for the loop closure constraint of pose-graph SLAM. We used the Incremental Smoothing and Mapping (iSAM) to optimize the graph. The optimized trajectory was compared against the dead reckoning (DR).

• Journal of the Semiconductor & Display Technology
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• v.18 no.3
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• pp.72-76
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• 2019

A Q-switched diode-pumped neodymium-doped yttrium vanadate (YVO₄, λ =1064nm) laser was used for the direct patterning of indium tin oxide (ITO) films on glass substrate. During the laser direct patterning, the laser beam was incident on the two different directions of glass substrate and the laser ablated patterns were compared and analyzed. At a low scanning speed of laser beam, the larger laser etched lines were obtained by laser beam incident in reverse side of glass substrate. On the contrary, at a higher scanning speed, the larger etched pattern sizes were found in case of the beam incidence from front side of glass substrate. Furthermore, it was impossible to find no ablated patterns in some laser beam conditions for the laser beam from reverse side at a much higher scanning speed and repetition rate of laser beam. The laser beam is expected to be transferred and scattered through the glass substrate and the laser beam energy is thought to be also dispersed and much more influenced by the overlapping of each laser beam spot.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.2
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• pp.90-95
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• 2001

f-$\theta$len is one of the important parts in Laser Scanning Unit because it affects on the optical performance of Laser Scanning Unit dominantly. It is necessary to find out the relationship between the surface profile error of f-$\theta$lens and the beam profile focusing on the Organic Photo Conductive drum in order to analysis the beam profile problems such as appearance of side lobe and expansion of center lobe. In this research, a simulation process which relates the surface profile characteristics to the beam profile has been developed by CODE V. The simulated beam profile also have been compared with the measurement results.

• The Journal of Korean Medicine
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• v.21 no.4
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• pp.148-158
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• 2000

Objective : The purpose of this study was to investigate the back shape of school children using the phase-shifting scanning grating projection moire interferometer, which was developed by the Korea Advanced Institute of Science and Technology and is useful in evaluating three dimensional back shape. Methods : In this study the subjects consisted of 1,358 pupils [711 boys(52.36%), 647 girls(47.64%)] attending elementary and middle schools in Seoul. Their ages ranged from nine to fifteen and the average age was 12.2. With the phase-shifting scanning grating projection moire interferometer, the posterior view of the body were taken to see if there are correlations of moire fringe number, width difference between left and right, and correlation between differences in moire fringe number and width on both sides in the scapular, lumbar and gluteal regions. Results : The results were as follows : I. More frequent findings of fringe were observed on the right in all regions : in the scapular region, 309 boys(43.4%) and 156 girls(24.2%) had more fringe numbers on the right side; in the lumbar region, 68 boys(9.5%) and 11 girls(1.7%); and in the gluteal region, 160 boys(22.4%) and 63 girls(9.8%). Such tendency was striking especially in the scapular and lumbar regions, and in boys rather than in girls. In the scapula, 661 subjects(48.7%) with one moire fringe on either side need further attention and 110 subjects(8.I %) with two or more are required to do follow-up radiography for scoliosis. 2. In an analysis of width difference in the trunk, the left side is wider in all regions except for the gluteal region in boys : in the scapular region 21 boys(3.0%) and 103 girls(15.9%); in the lumbar region, 87 boys(12.2%) and 250 girls(38.6%); and in the gluteal region 197 girls(30.4%) had a wider left side and 45 boys(6.3%) showed a wider right side. 3. In correlation analysis of the number of moire fringe and width difference in each region, the side where more moire fringes were observed was significantly wider in the lumbar and gluteal regions, but not in the scapular region.(p<0.01) Conclusions : From these results, it is concluded that the back shape of elementary and middle school students in Seoul shows that the right side had more moire fringes; the left side was wider; and especially in the lumbar and gluteal regions the side where more moire fringes were observed was wider.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.8
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• pp.1622-1631
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• 1997

A 3-stages Active Microstrip Phased Array Antenn(AMPAA) is implemented using Injection-Locking Coupled Oscillators(ILCO). The AMPAA is a beam scanning active antenna with capability of electrical scanning by frequency varation of ILCO. The synchronization of resonance frequencies in array elements is occured by ILCO, and the ILCO amplifies the injection signal and functions as a phase shifter. The microstrip ptch is operated as a radiation element. The unilateral amplifier is a mutual coupling element of AMPAA, eliminates the reverse locking signal and controls the locking bandwidth of ILCO. The possibility of Monolithic Microwave Integrated Circuits(MMIC) of T/R module is proposed by simplified and integrated fabrication process of AMPAA. The 0.75.$lambda_{0}$ is fixed for a mutual coupling space to wide the scanning angle and minimize the multi-mode. The AMPAA has beam scanning angle of 31.4.deg., HPBW(Half Power Beam Widths) of 26.deg., directive gain of 13.64dB and side lobe of -16.5dB were measured, respectively.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.11
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• pp.2752-2761
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• 1993

The purpose of this study is to confirm the decreasing problems of residual bending strength, and the fracture machanism experimentally when CFRP composite laminates are subjected to Foreign Object Damage. Composite laminates used for this experiment are CFRP orthotropy laminated plates, which have two-interfaces [O/sub 6//sup o//90/sub 6//sup o/]sub sym/ and four-interfaces [O/sub 3//sup o//90/sub 6//sup o//O/sub 3//sup o]/sub sym/. When the specimen is subjected to transverse impact by a steel ball, the delamination area generated by impact damage is observed by using SAM(Scanning Acoustic Microscope). also, Thefracture surfaces obtained by three-point bending test were observed by using SEM (Scanning Electron Microscope). Then, fracture mechanism was investigated based on the observed delamination area and fracture surface. The results were summarized as follows; (1) It is found that for the specimen with more interface, the critical delamination energy is increased while delamination-development energy is decreased. (2) Residual bending strength of specimen A is greater than that of Specimen B within the impact range of impact energy 1. 65J (impacted-side compression) and 1. 45J (impacted-side tension). On the other hand, when the impact energy is beyond the above ranges, residual bending strength of specimen A is smaller than that of specimen B. (3) In specimen A and B, residual strength of CFRP plates subjected to impact damage is lower in the impacted-side compression than in the impacted-side tension. (4) In the case of impacted-side compression, fracture is propagated from the transverse crack generat-ed near impact point. On the other hand, fracture is developed toward the impact point from the edge of interface-B delamination in the case of impacted-side tension.

• The Journal of the Korean dental association
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• v.49 no.11
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• pp.660-669
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• 2011

Er: YAG laser irradiation utilizing the newly developed RCLase side-firing spiral tip was used for the cleansing of root canals following their bio-mechanical preparation with ProTaper Ni-Ti files. The distal and palatal roots of 20 freshly extracted molar teeth were instrumented to size F3 with ProTaper files. In the experimental group (10 teeth) the pulp chamber and the root canals were filled with EDTA 17% and the root canals were lased for 30 s using the Er: YAG laser irradiation at 600 mJ per pulse and a frequency of 12 Hz. In the control group (10 teeth) the root canals were not lased. Scanning electron microscope analysis showed clean wall surfaces of the lased root canals with open dentinal tubules, free of smear layer and debris. In the scanning electron microscope photographs of the walls of the non-lased root canals a considerable amount of debris could be detected. It appears that an efficient cleansing of the root canal system can be achieved by using the Er: YAG laser irradiation with the RCLase Side-firing Spiral Tip following bio-mechanical preparation of the root canal with Ni-Ti Taper files.

• Proceedings of the KIEE Conference
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• 1998.11c
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• pp.1001-1003
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• 1998

In this paper, $Ar^+$ ion laser etching process of single/poly crystalline silicon with $CCl_{2}F_{2}$ gas is studied for MEMS applications. To investigate the effects of process parameters, laser power, gas pressure, scanning speed were varied and multiple scanning was carried out to obtain high aspect ratio. In addition, scanning width was varied to observe the trench profile etched in repeating scanning cycle. From the etching of $2.6{\mu}m$ thick polycrystalline Si deposited on insulator, trench with flat bottom and vertical side wall was obtained and it is possible to apply this results for MEMS applications.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.10a
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• pp.603-604
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• 2010

In this paper, we analyses a testing methodology that allows for harmless auditing, define three testing modes.heavy, relaxed, and safe modes, and report our results from two experiments. In the first, we compared the coverage and side effects of the three scanning modes using Web applications chosen from the different vulnerable in a previous static verification effort.

• Journal of the Korean Society of Safety
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• v.16 no.4
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• pp.7-13
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• 2001

Wire electrical discharge machining experiments in conducted to investigate characteristics of acoustic emission (AE) and electrical discharge energy due to current peak (I$_{p}$), pulse on time($\tau$/on/). The AE signals are obtained with a sensor attached to workpiece side. Machining states are identified with scanning electron microscopy and residual stress analyzer. It is demonstrated that the residual stress provide reliable informations about the machining states. Moreover, machining states can be detected successfully using both the residual stress and AE count rate.e.