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Configuration of GNSS CORS Network(EAREF) for Earth Observations in the East-Asia Region (동아시아지역의 GNSS CORS 지구관측 네트워크(EAREF) 구성에 관한 연구)

  • Lee, Young-Jin;Jung, Kwang-Ho;Lee, Myeong-Jun
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.30 no.2
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    • pp.199-210
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    • 2012
  • This paper is designed to put forth a proposal for configuration of an optimized observation network based on GNSS CORS with a view to continued monitoring of crustal deformation in the East-Asian region. For this purpose, a comprehensive analysis of the results of the testing of various forms of GNSS CORS observation network tentatively constructed based on the Asia-Pacific IGS station has confirmed that geometrically arranged minimum five and ten or more reference points and an EAREF, constructed with a baseline length no longer than 2,500km, can produce an optimum outcome. And an EAREF-applied analysis on the effects of the Great Eastern Japan Earthquake of March 2011 shows that there were conspicuous positional movements in Japan and Korea while there was no significant movement in other regions.

STUDY ON RADIOGRAPHIC EVALUATION OF MARGINAL BONE LOSS AROUND OSSEOINTEGRATED IMPLANT AFTER FUNCTIONAL LOADING (기능적 부하 후 임플란트 주변의 골 흡수에 대한 방사선학적 연구)

  • Choi, Su-Jin;Chee, Young-Deok;Koh, Se-Wook
    • Journal of the Korean Association of Oral and Maxillofacial Surgeons
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    • v.35 no.4
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    • pp.240-247
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    • 2009
  • Purpose: The purpose of this study was to evaluate marginal bone loss to the bone crest functionally loaded for up to eighteen months and also with regard to other variables of interest. Material and Methods: 135 endosseous implants(GS II, Osstem, South Korea) were placed in 35 patients. The design of GS II implant is straight with the microthread. Radiographic examinations were conducted at baseline (implant loading) and 3, 6, 9, 12 and 18 months after loading. Marginal bone level measurement was made from the reference point to the lowest observed point of contact of the marginal bone with the fixture. The reference point of the fixture was the border between the blasted surface and machined surface of the fixture. Results: Implants were on function for a mean 12.7 months(range, 3?18 months). For the 56 maxillary and 79 mandibular implants, mean marginal bone loss was 0.68 mm and 0.70 mm. Implants placed maxillary posterior area displayed more crestal bone loss than the other position. The difference between mesial and distal bone levels was statistically significant (p<0.05) with respective means of 0.51 mm and 0.62 mm. Also, The difference between bone graft group and no-bone graft group was statistically significant(p<0.05) with respective means of 0.38 mm and 0.66 mm. But no statistically significant influence of sex, type of surgery(one or two stage surgery), the implant length was observed(p>0.05). Conclusion: This study indicates the amount of marginal bone loss around implant has maintained a relative stable during follow-up periods.

An Evaluative Study on Forehead Morphology of Individuals with Normal Occlusion and Position of Maxillary Incisor in Accordance to Forehead Morphology (정상교합자의 이마형태와 그에 따른 상악 전치의 위치 평가)

  • Lee, Su-Yong;Lee, Jin-Woo;Cha, Kyung-Suk;Jung, Dong-Hwa;Lee, Sang-Min
    • Journal of Dental Rehabilitation and Applied Science
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    • v.29 no.3
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    • pp.236-248
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    • 2013
  • In this study, 37 subjects with normal facial shape and normal occlusion are classified and reference value for such classification was investigated. Difference in position of maxillary incisor was studied according to the cl assification. Moreover, by investigating correlation between factors affecting forehead morphology and positio n of maxillary incisor, following results have been obtained. 1. Morphology of forehead can be classified as angular type, round type, straight type, and concave type. 2. There were no specific reference value for evaluation of forehead morphology but possibilities of evaluating forehead morphology using S value and forehead length (Tri-Gla) still remain. 3. There were no correlation between forehead morphology and position of maxillary incisor. 4. Forehead inclination and Andrew analysis show statistically significant negative correlation. That is, as forehead inclination increases, maxillary incisor is positioned posteriorly and this relationship can be shown as following equation, Andrew analysis = -0.39*Forehead inclination.

Distribution of Vascular Canal at Lateral Wall of Maxillary Sinus in Korean Population Using Computed Tomography (컴퓨터단층촬영을 이용한 한국인의 상악동 측벽의 혈행 분포)

  • Song, Chi Bum;Kim, Chul Hwan
    • Maxillofacial Plastic and Reconstructive Surgery
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    • v.34 no.6
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    • pp.432-439
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    • 2012
  • Purpose: The aim of this study was to investigate the blood supply to the maxillary sinus in Koreans using computed tomography of the lateral wall of the sinus, and to analyze the data according to demographic data, and to compare our results with previously published research. Methods: One hundred and three patients (males 51, females 52) who visited the dental clinic were evaluated. We investigated the canals with cone-beam computed tomography, and measured the diameter and length from the bony notch of the vascular canal at the lateral wall of the sinus to each of the reference planes. Results: Most types of vascular canal were type I & II (total 72.2%) which were driving through inside the sinus wall. Type IV, V were frequently investigated in 1st premolar and 2nd molar. Mean height; from anterior nasal spine-posterior nasal spine plane to vascular canal was 5.56 mm in 1st premolar, 2.11 mm in 2nd premolar, 0.98 mm in 1st molar, 4.32 mm in 2nd molar; from the basal layer of the sinus was 4.93 mm in 1st premolar, 5.00 mm in 2nd premolar, 6.05 mm in 1st molar, 7.91 mm in 2nd molar; and from alveolar crest, 20.80 mm in 1st premolar, 16.57 mm in 2nd premolar, 14.01 mm in 1st molar, 16.17 mm in 2nd molar. The mean height of the vascular canal of each reference plane showed no significant difference between sex, site (left or right) and age. The mean diameters of the canals were 1.76 mm in male, and 1.50 mm in female. Diameter decreased with age, and tooth site (from 1st premolar to 2nd molar). Conclusion: These results show that the mean diameter of the vascular canal of the maxillary sinus varies according to age, sex, and tooth site, but that the mean height of canal had no significant difference based on these three factors.

Structural Performance Evaluation of Prestressed Concrete Trapezoidal Girders Using Socket Joint System (소켓연결 방식을 이용한 프리스트레스트 콘크리트 제형 거더의 구조성능 평가)

  • Shim, Won-Bo;Min, Kyung-Hwan;Choi, Hong-Sik
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.16 no.11
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    • pp.7244-7249
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    • 2015
  • In this study, in order to asses the structural performance of trapezoidal PSC girder using a socket joint system and it is possible to calculate the optimized cross-section of the web element tests were carried out for each specimens. we conducted a socket joint performance test, web bending and shear performance tests and all tests were performed at 4 point loading method. The initial crack load of socket joint specimen was significantly lower than the reference specimen but post peak behavior was no significant differences. And the length of the loop joint of the reinforcing bars had no significant effect on the maximum load. As a web shear tests, to obtain a maximum load of the specimen has a prestressing rod reinforced at tension side. As a web flexural tests, to obtain higher diagonal cracking load in specimen of reinforced using prestressing rod than reference specimen.

Assessment of Magnetic Field Mitigation and Electrical Environmental Effects for Commercially Operating 154kV Transmission Lines with Passive Loop

  • Lee, Byeong-Yoon;Myung, Sung-Ho;Ju, Mun-No;Cho, Yeun-Gyu;Lee, Dong-Il;Lim, Yun-Seog;Kim, Sang-Beom
    • Journal of Electrical Engineering and Technology
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    • v.9 no.3
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    • pp.991-996
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    • 2014
  • Power frequency magnetic field is still a critical problem for new construction of overhead power transmission lines in Korea because most people have been concerned about possibly carcinogenic effects of it. Although reference level of power frequency(60Hz) magnetic field has been set to 200uT in ICNIRP guidelines published in 2010, Korean government has no intention of adjusting 83.3uT specified by law in 2006 to this new reference level in consideration of people's concerns for the time being. Regardless of the current regulated magnetic field value, electric utility company has been trying to reduce magnetic field in the residential area in the vicinity of overhead power transmission lines to take into account of public concerns on the long-term effect of magnetic fields. In an effort to reduce magnetic field, engineering side has made considerable efforts to develop passive loop based, cost-effective mitigation technique of power frequency magnetic field more than ten years. In order to verify developed power frequency magnetic field mitigation technique based on passive loop, a horizontal type of passive loop was designed and installed for commercially operating 154kV overhead power transmission line for the first time in Korea. The measurement results before and after the installation of passive loop showed that magnetic field could be reduced to about 20%. The electrical environmental effects such as AN, RI and TVI were assessed before and after the installation of passive loop and these values were complied with the requirements specified by electric utility. It has been confirmed from the field test results that passive loop could be commercially and cost-effectively utilized to mitigate power frequency magnetic field.

Feasibility Study of Non Local Means Noise Reduction Algorithm with Improved Time Resolution in Light Microscopic Image (광학 현미경 영상 기반 시간 분해능이 향상된 비지역적 평균 노이즈 제거 알고리즘 가능성 연구)

  • Lee, Youngjin;Kim, Ji-Youn
    • Journal of the Korean Society of Radiology
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    • v.13 no.4
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    • pp.623-628
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    • 2019
  • The aim of this study was to design fast non local means (FNLM) noise reduction algorithm and to confirm its application feasibility in light microscopic image. For that aim, we acquired mouse first molar image and compared between previous widely used noise reduction algorithm and our proposed FNLM algorithm in acquired light microscopic image. Contrast to noise ratio, coefficient of variation, and no reference-based evaluation parameter such as natural image quality evaluator (NIQE) and blind/referenceless image spatial quality evaluator (BRISQUE) were used in this study. According to the result, our proposed FNLM noise reduction algorithm can achieve excellent result in all evaluation parameters. In particular, it was confirmed that the NIQE and BRISQUE evaluation parameters for analyzing the overall morphologcal image of the tooth were 1.14 and 1.12 times better than the original image, respectively. In conclusion, we demonstrated the usefulness and feasibility of FNLM noise reduction algorithm in light microscopic image of small animal tooth.

Use of measuring gauges for in vivo accuracy analysis of intraoral scanners: a pilot study

  • Iturrate, Mikel;Amezua, Xabier;Garikano, Xabier;Solaberrieta, Eneko
    • The Journal of Advanced Prosthodontics
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    • v.13 no.4
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    • pp.191-204
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    • 2021
  • PURPOSE. The purpose of this study is to present a methodology to evaluate the accuracy of intraoral scanners (IOS) used in vivo. MATERIALS AND METHODS. A specific feature-based gauge was designed, manufactured, and measured in a coordinate measuring machine (CMM), obtaining reference distances and angles. Then, 10 scans were taken by an IOS with the gauge in the patient's mouth and from the obtained stereolithography (STL) files, a total of 40 distances and 150 angles were measured and compared with the gauge's reference values. In order to provide a comparison, there were defined distance and angle groups in accordance with the increasing scanning area: from a short span area to a complete-arch scanning extension. Data was analyzed using software for statistical analysis. RESULTS. Deviations in measured distances showed that accuracy worsened as the scanning area increased: trueness varied from 0.018 ± 0.021 mm in a distance equivalent to the space spanning a four-unit bridge to 0.106 ± 0.08 mm in a space equivalent to a complete arch. Precision ranged from 0.015 ± 0.03 mm to 0.077 ± 0.073 mm in the same two areas. When analyzing angles, deviations did not show such a worsening pattern. In addition, deviations in angle measurement values were low and there were no calculated significant differences among angle groups. CONCLUSION. Currently, there is no standardized procedure to assess the accuracy of IOS in vivo, and the results show that the proposed methodology can contribute to this purpose. The deviations measured in the study show a worsening accuracy when increasing the length of the scanning area.

Analysis of the trueness and precision of complete denture bases manufactured using digital and analog technologies

  • Leonardo Ciocca;Mattia Maltauro;Valerio Cimini;Lorenzo Breschi;Angela Montanari;Laura Anderlucci;Roberto Meneghello
    • The Journal of Advanced Prosthodontics
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    • v.15 no.1
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    • pp.22-32
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    • 2023
  • PURPOSE. Digital technology has enabled improvements in the fitting accuracy of denture bases via milling techniques. The aim of this study was to evaluate the trueness and precision of digital and analog techniques for manufacturing complete dentures (CDs). MATERIALS AND METHODS. Sixty identical CDs were manufactured using different production protocols. Digital and analog technologies were compared using the reference geometric approach, and the Δ-error values of eight areas of interest (AOI) were calculated. For each AOI, a precise number of measurement points was selected according to sensitivity analyses to compare the Δ-error of trueness and precision between the original model and manufactured prosthesis. Three types of statistical analysis were performed: to calculate the intergroup cumulative difference among the three protocols, the intergroup among the AOIs, and the intragroup difference among AOIs. RESULTS. There was a statistically significant difference between the dentures made using the oversize process and injection molding process (P < .001), but no significant difference between the other two manufacturing methods (P = .1227). There was also a statistically significant difference between the dentures made using the monolithic process and the other two processes for all AOIs (P = .0061), but there was no significant difference between the other two processes (P = 1). Within each group, significant differences among the AOIs were observed. CONCLUSION. The monolithic process yielded better results, in terms of accuracy (trueness and precision), than the other groups, although all three processes led to dentures with Δ-error values well within the clinical tolerance limit.

Evaluation of Performance and No-reference-based Quality for CT Image with ADMIRE Iterative Reconstruction Parameters: A Pilot Study (ADMIRE 반복적 재구성 파라메터에 따른 CT 영상의 특성 및 무참조 기반 화질 평가: 선행연구)

  • Bo-Min Park;Yoo-Jin Seo;Seong-Hyeon Kang;Jina Shim;Hajin Kim;Sewon Lim;Youngjin Lee
    • Journal of radiological science and technology
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    • v.47 no.3
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    • pp.175-182
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    • 2024
  • Advanced modeled iterative reconstruction (ADMIRE) represents a repetitive reconstruction method that can adjust strength and kernel, each of which are known to affect computed tomography (CT) image quality. The aim of this study was to quantitatively analyze the noise and spatial resolution of CT images according to ADMIRE control factors. Patient images were obtained by applying ADMIRE strength 2 and 3, and kernel B40 and B59. For quantitative evaluations, the noise level, spatial resolution, and overall image quality were measured using coefficient of variation (COV), edge rise distance (ERD), and natural image quality evaluation (NIQE). The superior values for the average COV, ERD, and NIQE results were obtained for the ADMIRE reconstruction conditions of ADMIRE 2 + B40, ADMIRE 3 + B59, and ADMIRE3 + B59. NIQE, which represents the overall image quality based on no-reference, was about 6.04 when using ADMIRE 3 + B59, showing the best result among the reconstructed image acquisition conditions. The results of this study indicate that the ADMIRE strength and kernel chosen for use in ADMIRE reconstruction have a significant impact on CT image quality. This highlights the importance of adjusting to the control factors in consideration of the clinical environment.