• Title/Summary/Keyword: Laser

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Admittance Model-Based Nanodynamic Control of Diamond Turning Machine (어드미턴스 모델을 이용한 다이아몬드 터닝머시인의 초정밀진동제어)

  • Jeong, Sanghwa;Kim, Sangsuk
    • Journal of the Korean Society for Precision Engineering
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    • v.13 no.10
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    • pp.154-160
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    • 1996
  • The control of diamond turning is usually achieved through a laser-interferometer feedback of slide position. The limitation of this control scheme is that the feedback signal does not account for additional dynamics of the tool post and the material removal process. If the tool post is rigid and the material removal process is relatively static, then such a non-collocated position feedback control scheme may surfice. However, as the accuracy requirement gets tighter and desired surface cnotours become more complex, the need for a direct tool-tip sensing becomes inevitable. The physical constraints of the machining process prohibit any reasonable implementation of a tool-tip motion measurement. It is proposed that the measured force normal to the face of the workpiece can be filtered through an appropriate admittance transfer function to result in the estimated dapth of cut. This can be compared to the desired depth of cut to generate the adjustment control action in additn to position feedback control. In this work, the design methodology on the admittance model-based control with a conventional controller is presented. The recursive least-squares algorithm with forgetting factor is proposed to identify the parameters and update the cutting process in real time. The normal cutting forces are measured to identify the cutting dynamics in the real diamond turning process using the precision dynamoneter. Based on the parameter estimation of cutting dynamics and the admitance model-based nanodynamic control scheme, simulation results are shown.

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Antagonistic Potentiality of Actinomycete-Derived Extract with Anti-Biofilm, Antioxidant, and Cytotoxic Capabilities as a Natural Combating Strategy for Multidrug-Resistant ESKAPE Pathogens

  • Mohamed H. El-Sayed;Fahdah A. Alshammari;Mohammed H. Sharaf
    • Journal of Microbiology and Biotechnology
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    • v.33 no.1
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    • pp.61-74
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    • 2023
  • The global increase in multidrug-resistant (MDR) bacteria has inspired researchers to develop new strategies to overcome this problem. In this study, 23 morphologically different, soil-isolated actinomycete cultures were screened for their antibacterial ability against MDR isolates of ESKAPE pathogens. Among them, isolate BOGE18 exhibited a broad antibacterial spectrum, so it was selected and identified based on cultural, morphological, physiological, and biochemical characteristics. Chemotaxonomic analysis was also performed together with nucleotide sequencing of the 16S rRNA gene, which showed this strain to have identity with Streptomyces lienomycini. The ethyl acetate extract of the cell-free filtrate (CFF) of strain BOGE18 was evaluated for its antibacterial spectrum, and the minimum inhibitory concentration (MIC) ranged from 62.5 to 250 ㎍/ml. The recorded results from the in vitro anti-biofilm microtiter assay and confocal laser scanning microscopy (CLSM) of sub-MIC concentrations revealed a significant reduction in biofilm formation in a concentration-dependent manner. The extract also displayed significant scavenging activity, reaching 91.61 ± 4.1% and 85.06 ± 3.14% of 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), respectively. A promising cytotoxic ability against breast (MCF-7) and hepatocellular (HePG2) cancer cell lines was obtained from the extract with IC50 values of 47.15 ± 13.10 and 122.69 ± 9.12 ㎍/ml, respectively. Moreover, based on gas chromatography-mass spectrometry (GC-MS) analysis, nine known compounds were detected in the BOGE18 extract, suggesting their contribution to the multitude of biological activities recorded in this study. Overall, Streptomyces lienomycini BOGE18-derived extract is a good candidate for use in a natural combating strategy to prevent bacterial infection, especially by MDR pathogens.

Deriving the Role of Sign Facilities Recognized by Autonomous Vehicles (자율주행차량이 인식 가능한 표지 시설의 역할 도출)

  • Young-Jae JEON;Jin-Woo KIM;Chan-Oh KWON;Jun-Hyuk LEE
    • Journal of the Korean Association of Geographic Information Studies
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    • v.26 no.1
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    • pp.1-10
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    • 2023
  • With the advent of the 4th industrial revolution era, interest in autonomous driving technology is increasing. Accordingly it is necessary to seek safe driving by recognizing surrounding situations using sensors attached to autonomous vehicles along with the applicability of existing traffic facilities to autonomous driving lanes and the utilization of HD maps. In this study, in order to deduce the role of sensor only physical facilities which recognized through a laser scanner on an autonomous vehicle developed to improve road and traffic infrastructure, through comparative analysis with existing road facilities such as road signs, safety signs, and gaze guidance facilities. Sign facilities can promote driving safety by allowing autonomous vehicles to perform specific actions directly. In order to promote safe driving by recognizing sign facilities by using sensors for autonomous vehicles, it is necessary to prepare standards for installation, management, and use, and it is considered that management and supervision should be carried out continuously according to the standards.

A Study of the Optimal Displacement Analysis Algorithm for Retaining Wall Displacement Measurement System Based on 2D LiDAR Sensor (2D LiDAR 센서 기반 흙막이 벽체 변위 계측 시스템의 최적 변위 분석 알고리즘 연구)

  • Kim, Jun-Sang;Lee, Gil-yong;Yoou, Geon hee;Kim, Young Suk
    • Korean Journal of Construction Engineering and Management
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    • v.24 no.2
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    • pp.70-78
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    • 2023
  • Inclinometer has several problems of 1)difficulty installing inclinometer casing, 2) measuring 2D local lateral displacement of retaining wall, 3) measurement by manpower. To solve such problems, a 2D LiDAR sensor-based retaining wall displacement measurement system was developed in previous studies. The purpose of this study is to select a displacement analysis algorithm to be applied in the retaining wall displacement measurement system. As a result of the displacement analysis algorithm selection, the M3C2 (Multiple Model to Model Cloud Comparison) algorithm with a displacement estimation error of 2mm was selected as the displacement analysis algorithm. If the M3C2 algorithm is applied in the system and the reliability of the displacement analysis result is secured through several field experiments. Convenient management of the displacement for the retaining wall is possible in comparison with the current measurement management.

Evaluation of trueness and precision of removable partial denture metal frameworks manufactured with digital technology and different materials

  • Leonardo Ciocca;Mattia Maltauro;Elena Pierantozzi;Lorenzo Breschi;Angela Montanari;Laura Anderlucci;Roberto Meneghello
    • The Journal of Advanced Prosthodontics
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    • v.15 no.2
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    • pp.55-62
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    • 2023
  • PURPOSE. The aim of this study is to evaluate the accuracy of removable partial denture (RPD) frameworks produced using different digital protocols. MATERIALS AND METHODS. 80 frameworks for RPDs were produced using CAD-CAM technology and divided into four groups of twenty (n = 20): Group 1, Titanium frameworks manufactured by digital metal laser sintering (DMLS); Group 2, Co-Cr frameworks manufactured by DMLS; Group 3, Polyamide PA12 castable resin manufactured by multi-jet fusion (MJF); and Group 4, Metal (Co-Cr) casting by using lost-wax technique. After the digital acquisition, eight specific areas were selected in order to measure the Δ-error value at the intaglio surface of RPD. The minimum value required for point sampling density (0.4 mm) was derived from the sensitivity analysis. The obtained Δ-error mean value was used for comparisons: 1. between different manufacturing processes; 2. between different manufacturing techniques in the same area of interest (AOI); and 3. between different AOI of the same group. RESULTS. The Δ-error mean value of each group ranged between -0.002 (Ti) and 0.041 (Co-Cr) mm. The Pearson's Chi-squared test revealed significant differences considering all groups paired two by two, except for group 3 and 4. The multiple comparison test documented a significant difference for each AOI among group 1, 3, and 4. The multiple comparison test showed significant differences among almost all different AOIs of each group. CONCLUSION. All Δ-mean error values of all digital protocols for manufacturing RPD frameworks optimally fit within the clinical tolerance limit of trueness and precision.

Calibration of Borehole Roughness Measurement System for Large Diameter Drilled Shafts in Water (수중에서 적용가능한 대구경 현장타설말뚝의 굴착공 벽면거칠기 측정장치의 보정에 관한 연구)

  • Park, Bong-Geun;Nam, Moon-S.;Choi, Yong-Kyu
    • Journal of the Korean Geotechnical Society
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    • v.25 no.8
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    • pp.5-21
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    • 2009
  • Based on recent studies on rock socketed drilled shafts, it was found that the side resistance of rock socketed drilled shafts is affected by unconfined compressive strength of rock, socket roughness, rock types and joints, and initial normal stress. Especially, the socket roughness is affected by rock types and joints, drilling methods, and diameters. Since existing roughness measurement systems could be conducted only in the air, a new roughness measurement system, which can measure rock socket roughness in the air and also in the water, is needed. However, the development of new roughness measurement system fur civil engineers has been faced with difficulties of electrical applications. In this study, the laboratory verification system far BKS-LRPS (Backyoung-KyungSung Laser Roughness Profiling System) was developed, which can be applied both in the water and air. Based on the laboratory verification, it was found that the improved BKS-LRPS could define effective measurement distances for the conditions reflecting the apparatus and in-situ situations.

Evaluation of RPL Glass Dosimeter Characteristics and Uncertainty Evaluation of Reading Correction Factors (유리선량계 특성평가 및 판독 보정인자에 대한 불확도 평가)

  • Seong-Yun Mok;Yeong-Rok Kang;Hyo-Jin Kim;Yong-Uk Kye;Hyun An
    • Journal of radiological science and technology
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    • v.46 no.3
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    • pp.219-229
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    • 2023
  • In this study, basic characteristics such as reproducibility, linearity, and directionality of RPL glass dosimeters were evaluated to improve the reliability of dose evaluation through RPL glass dosimeters, and uncertainty elements such as sensitivity by glass element and magazine slot sensitivity were evaluated. Using a mathematical model to calibrate the measured values of the RPL glass dosimeter, the measurement uncertainty was calculated assuming an example. As a result of the characteristic evaluation, the RPL glass dosimeter showed excellent performance with a standard deviation of ±1% (1 SD) for the reproducibility of the reading process, a coefficient of determination for linearity of 0.99997. And the read-out of the RPL glass dosimeter are affected by the circular rotation direction of the glass dosimeter during irradiation, fading according to the period after irradiation, the number of laser pulses of the reader, and response degradation due to repeated reading, it is judged that measurement uncertainty can be reduced by irradiation and reading in consideration of these factors. In addition, it was confirmed that the dose should be determined by calculating the correction factors for the sensitivity of each element and, the sensitivity of each reading magazine slot. It is believed that the reliability of dosimetry using glass dosimeters can be improved by using a mathematical model for correction of glass dosimeter readings and calculating measurement uncertainty.

Displacement Evaluation of Cable Supported Bridges Using Inclinometers (경사계를 이용한 케이블교량의 변위 산정)

  • Kong, Min Joon;Yun, Jung Hyun;Kang, Seong In;Gil, Heungbae
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.43 no.3
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    • pp.297-308
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    • 2023
  • Displacement of structures is the most important parameter for safety and performance assessment and is measured to use for diagnosis and maintenance of bridges. Usually LVDT, Laser and GNSS are used for displacement measurement but these measurement instruments have problems in terms of field condition and cost. Therefore, in this study, displacements were evaluated using rotational angle measured by inclinometers and the proposed algorithm was experimentally verified. As the result, vertical displacements of cable supported bridges with traffic and temperature load were properly evaluated through the proposed algorithm. Therefore it is considered that the proposed algorithm can be used for displacement measurement by vehicle load test and long term displacement monitoring.

Quantitative Analysis of 3D Printing Layered Shape according to the Flatness of Construction Surface (시공표면평탄에 따른 3D 프린팅 적층형상 정량분석)

  • Park, Jin Su;Kim, Kyung Taek
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.42 no.2
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    • pp.257-261
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    • 2022
  • Additive manufacturing (AM, also known as 3D printing) applied to the construction industry is implemented and verified for various effects since advantages such as high design freedom, improving worker safety, and predictable construction period. However, due to the low maturity compared to the existing technology, studies are underway to solve new problems that occur in the overall of AM technology. In this paper, we confirm the effect of low construction surface flatness on the stacked features in the process of on-site AM construction. In particular, unstable AM features are determined through quantitative analysis by laser scanning, and a construction strategy is proposed for the surface flattening.

Data Assimilation of Aeolus/ALADIN Horizontal Line-Of-Sight Wind in the Korean Integrated Model Forecast System (KIM 예보시스템에서의 Aeolus/ALADIN 수평시선 바람 자료동화)

  • Lee, Sihye;Kwon, In-Hyuk;Kang, Jeon-Ho;Chun, Hyoung-Wook;Seol, Kyung-Hee;Jeong, Han-Byeol;Kim, Won-Ho
    • Atmosphere
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    • v.32 no.1
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    • pp.27-37
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    • 2022
  • The Korean Integrated Model (KIM) forecast system was extended to assimilate Horizontal Line-Of-Sight (HLOS) wind observations from the Atmospheric Laser Doppler Instrument (ALADIN) on board the Atmospheric Dynamic Mission (ADM)-Aeolus satellite. Quality control procedures were developed to assess the HLOS wind data quality, and observation operators added to the KIM three-dimensional variational data assimilation system to support the new observed variables. In a global cycling experiment, assimilation of ALADIN observations led to reductions in average root-mean-square error of 2.1% and 1.3% for the zonal and meridional wind analyses when compared against European Centre for Medium-Range Weather Forecasts (ECMWF) Integrated Forecast System (IFS) analyses. Even though the observable variable is wind, the assimilation of ALADIN observation had an overall positive impact on the analyses of other variables, such as temperature and specific humidity. As a result, the KIM 72-hour wind forecast fields were improved in the Southern Hemisphere poleward of 30 degrees.