• Title, Summary, Keyword: STL

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Three-dimensional analysis of artificial teeth position according to three type complete mandibular denture before and after polymerization (세 가지 방식으로 제작한 하악 총의치의 중합 전후에 따른 인공치아 위치 3차원 분석)

  • Park, Jin-Young;Kim, Dong-Yeon;Kim, Won-Soo;Lee, Gwang-Young;Jeong, Il-Do;Bae, So-Yeon;Kim, Ji-Hwan;Kim, Woong-Chul
    • The Journal of Korean Academy of Dental Technology
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    • v.40 no.4
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    • pp.217-224
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    • 2018
  • Purpose: The aim of this study was to evaluate accuracy of three type complete mandibular denture of before and after polymerization. Methods: Mandibular edentulous model was selected as the master model. 15 study models were made by Type IV stone. Wax complete mandibular dentures were produced by the denture base and artificial teeth. Before and after curing, STL files were obtained using a blue scanner. By superimposing the digitized complete mandibular denture data(after curing) with the CAD-reference(before curing) three-dimensionally, visual fit-discrepancies were drawn by calculating the root mean square (RMS) and visualized on a color-difference map. Each calculated RMS-value was statistically analyzed by 1-way analysis of variance(ANOVA) (${\alpha}=.05$). Results: Mean(SD) RMS-values was OM group $88.98(6.10){\mu}m$, BM group $82.35(13.46){\mu}m$, BDM group $77.83(9.46){\mu}m$. The results of the 1-way ANOVA showed no statistically significant differences in the RMS values of the Three groups for the material (P > .241). Conclusion : Deformation of artificial teeth position was observed in all groups after resin polymerization. But the values, all group were within the clinically acceptable range. The values of BDM group showed the least deformation than the other two groups.

Hip Range of Motion Estimation using CT-derived 3D Models (CT기반 3차원 모델을 이용한 고관절 운동범위 예측)

  • Lee, Yeon Soo
    • Journal of the Korean Society of Radiology
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    • v.12 no.1
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    • pp.115-122
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    • 2018
  • The success of the total hip arthroplasty is revealed as initial stability, range of motion, and long term pain, etc. Depending upon choice of implantation options such as femoral neck offset, diameter of the femoral head, the lateral opening tilt. Especially the impingement between femoral head component and acetabular cup limits the range of motion of the hip. In this sense, estimation or evaluation of the range of motion before and after the total hip arthroplasty is important. This study provides the details of a computer simulation technique for the hip range of motion of intact hip as well as arthroplasty. The suggested method defines the hip rotation center and rotation axes for flexion and abduction, respectively. The simulation uses CT-based reconstructed 3D models and an STL treating software. The abduction angle of the hip is defined as the superolateral rotation angle from sagittal plane. The flexion angle of the hip is defined as the superoanterior angle from the coronal plane. The maximum abduction angle is found as the maximum rotation angle by which the femoral head can rotate superolaterally about the anterior-posterior axis without impingement. The maximum flexion angle is found as the maximum rotation angle by which the femoral head can rotate superoanteriorly about the medial-lateral axis without impingement. Compared to the normal hip, the total hip replacement hip showed decreased abduction by 60 degrees and decreased flexion by 4 degrees. This measured value implies that the proposed measurement technique can make surgeons find a modification of increase in the femoral neck offset or femoral head, to secure larger range of motion.

A Convergence Study on the 5-axis Machining Technology using the DICOM Image of the Humerus Bone (위팔뼈 의료용 디지털 영상 및 통신 표준 영상을 이용한 5축 가공기술의 융합적 연구)

  • Yoon, Jae-Ho;Ji, Tae-Jeong;Yoon, Joon;Kim, Hyeong-Gyun
    • Journal of the Korea Convergence Society
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    • v.8 no.11
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    • pp.115-121
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    • 2017
  • The present study aimed to obtain basic knowledge of a customized artificial joint based on the convergence research of Digital Imaging and Communications in Medicine(DICOM) and 5-axis machining technology. In the case of the research method, three-dimensional modeling was generated based on the medical image of the humerus bone, and the shape was machined using a chemical wood material. Then, the anatomical characteristics and the modeling machining computation times were compared. The results showed that the Stereolithography (STL) modeling required twice more time for semi-finishing and 10 times more time for finishing compared to the Initial Graphics Exchange Specification(IGES) modeling. For the 5-axis machining humerus bone, the anatomical structures of the anatomic neck, greater tubercle, lesser tubercle, and intertubercular groove were similar to those in the three-dimensional medical image. In the future, the convergence machining technology, where 5-axis machining of various structures(e.g., the surgical neck undercut of the humerus bone) is performed as described above, can be efficiently applied to the manufacture of a customized joint that pursues the precise model of a human body.

Development of a Korean Speech Recognition Platform (ECHOS) (한국어 음성인식 플랫폼 (ECHOS) 개발)

  • Kwon Oh-Wook;Kwon Sukbong;Jang Gyucheol;Yun Sungrack;Kim Yong-Rae;Jang Kwang-Dong;Kim Hoi-Rin;Yoo Changdong;Kim Bong-Wan;Lee Yong-Ju
    • The Journal of the Acoustical Society of Korea
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    • v.24 no.8
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    • pp.498-504
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    • 2005
  • We introduce a Korean speech recognition platform (ECHOS) developed for education and research Purposes. ECHOS lowers the entry barrier to speech recognition research and can be used as a reference engine by providing elementary speech recognition modules. It has an easy simple object-oriented architecture, implemented in the C++ language with the standard template library. The input of the ECHOS is digital speech data sampled at 8 or 16 kHz. Its output is the 1-best recognition result. N-best recognition results, and a word graph. The recognition engine is composed of MFCC/PLP feature extraction, HMM-based acoustic modeling, n-gram language modeling, finite state network (FSN)- and lexical tree-based search algorithms. It can handle various tasks from isolated word recognition to large vocabulary continuous speech recognition. We compare the performance of ECHOS and hidden Markov model toolkit (HTK) for validation. In an FSN-based task. ECHOS shows similar word accuracy while the recognition time is doubled because of object-oriented implementation. For a 8000-word continuous speech recognition task, using the lexical tree search algorithm different from the algorithm used in HTK, it increases the word error rate by $40\%$ relatively but reduces the recognition time to half.

Development of Mathematics 3D-Printing Tools with Sage - For College Education - (Sage를 활용한 수학 3D 프린팅 웹 도구 개발 - 대학 수학교육을 중심으로 -)

  • Lee, Jae-Yoon;Lim, Yeong-Jun;Park, Kyung-Eun;Lee, Sang-Gu
    • Communications of Mathematical Education
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    • v.28 no.3
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    • pp.353-366
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    • 2014
  • Recently, the widespread usage of 3D-Printing has grown rapidly in popularity and development of a high level technology for 3D-Printing has become more necessary. Given these circumstances, effectively using mathematical knowledge is required. So, we have developed free web tools for 3D-Printing with Sage, for mathematical 3D modeling and have utilized them in college education, and everybody may access and utilize online anywhere at any time. In this paper, we introduce the development of our innovative 3D-Printing environment based on Calculus, Linear Algebra, which form the basis for mathematical modeling, and various 3D objects representing mathematical concept. By this process, our tools show the potential of solving real world problems using what students learn in university mathematics courses.

Vegetation Structure and Management Plan for Windbreak Forests along the West Coast in Korea (서해안 방풍림의 식생구조 및 관리 방안)

  • Kim, Hyun-Jun;Jeong, Seong-Hun;Hwang, Chang-Hyuk;Kim, Hyun;Choi, Soo-Min;Lee, Sang-Hyun
    • Journal of agriculture & life science
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    • v.46 no.1
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    • pp.71-81
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    • 2012
  • This study was conducted to get basic information about making windbreak forest around Saemanguem reclaimed lands by analyzing the vegetation structure of 8 windbreak forests along the west coast of Korea and considering the methods of structural improvement. The total plants existing in the study areas were 25 families 40genus 43 species, and every tree layer consisted of only one tree species, Pinus thunbergii. There were 2 windbreak stands consisted of a species, and 2 consisted of multiple layer with a species. While, 4 windbreak stands consist of various species with several species. To make ecological system and functions of windbreak forests stabler, TL, STL and SL should be together in the vertical point, moreover, TL should be appeared at the in side and SL should be planted at the out side in the horizontal point. It is considered that mixed stand forest might be suitable for increasing the windbreak forest's functions and decreasing damage caused by disease and insects.

In vitro evaluation of the wear resistance of provisional resin materials fabricated by different methods (제작방법에 따른 임시 수복용 레진의 마모저항성에 관한 연구)

  • Ahn, Jong-Ju;Huh, Jung-Bo;Choi, Jae-Won
    • The Journal of Korean Academy of Prosthodontics
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    • v.57 no.2
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    • pp.110-117
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    • 2019
  • Purpose: This study was to evaluate the wear resistance of 3D printed, milled, and conventionally cured provisional resin materials. Materials and methods: Four types of resin materials made with different methods were examined: Stereolithography apparatus (SLA) 3D printed resin (S3P), digital light processing (DLP) 3D printed resin (D3P), milled resin (MIL), conventionally self-cured resin (CON). In the 3D printed resin specimens, the build orientation and layer thickness were set to $0^{\circ}$ and $100{\mu}m$, respectively. The specimens were tested in a 2-axis chewing simulator with the steatite as the antagonist under thermocycling condition (5 kg, 30,000 cycles, 0.8 Hz, $5^{\circ}C/55^{\circ}C$). Wear losses of the specimens were calculated using CAD software and scanning electron microscope (SEM) was used to investigate wear surface of the specimens. Statistical significance was determined using One-way ANOVA and Dunnett T3 analysis (${\alpha}=.05$). Results: Wear losses of the S3P, D3P, and MIL groups significantly smaller than those of the CON group (P < .05). There was no significant difference among S3P, D3P, and MIL group (P > .05). In the SEM observations, in the S3P and D3P groups, vertical cracks were observed in the sliding direction of the antagonist. In the MIL group, there was an overall uniform wear surface, whereas in the CON group, a distinct wear track and numerous bubbles were observed. Conclusion: Within the limits of this study, provisional resin materials made with 3D printing show adequate wear resistance for applications in dentistry.

Efficacy and Accuracy of Patient Specific Customize Bolus Using a 3-Dimensional Printer for Electron Beam Therapy (전자선 빔 치료 시 삼차원프린터를 이용하여 제작한 환자맞춤형 볼루스의 유용성 및 선량 정확도 평가)

  • Choi, Woo Keun;Chun, Jun Chul;Ju, Sang Gyu;Min, Byung Jun;Park, Su Yeon;Nam, Hee Rim;Hong, Chae-Seon;Kim, MinKyu;Koo, Bum Yong;Lim, Do Hoon
    • Progress in Medical Physics
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    • v.27 no.2
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    • pp.64-71
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    • 2016
  • We develop a manufacture procedure for the production of a patient specific customized bolus (PSCB) using a 3D printer (3DP). The dosimetric accuracy of the 3D-PSCB is evaluated for electron beam therapy. In order to cover the required planning target volume (PTV), we select the proper electron beam energy and the field size through initial dose calculation using a treatment planning system. The PSCB is delineated based on the initial dose distribution. The dose calculation is repeated after applying the PSCB. We iteratively fine-tune the PSCB shape until the plan quality is sufficient to meet the required clinical criteria. Then the contour data of the PSCB is transferred to an in-house conversion software through the DICOMRT protocol. This contour data is converted into the 3DP data format, STereoLithography data format and then printed using a 3DP. Two virtual patients, having concave and convex shapes, were generated with a virtual PTV and an organ at risk (OAR). Then, two corresponding electron treatment plans with and without a PSCB were generated to evaluate the dosimetric effect of the PSCB. The dosimetric characteristics and dose volume histograms for the PTV and OAR are compared in both plans. Film dosimetry is performed to verify the dosimetric accuracy of the 3D-PSCB. The calculated planar dose distribution is compared to that measured using film dosimetry taken from the beam central axis. We compare the percent depth dose curve and gamma analysis (the dose difference is 3%, and the distance to agreement is 3 mm) results. No significant difference in the PTV dose is observed in the plan with the PSCB compared to that without the PSCB. The maximum, minimum, and mean doses of the OAR in the plan with the PSCB were significantly reduced by 9.7%, 36.6%, and 28.3%, respectively, compared to those in the plan without the PSCB. By applying the PSCB, the OAR volumes receiving 90% and 80% of the prescribed dose were reduced from $14.40cm^3$ to $0.1cm^3$ and from $42.6cm^3$ to $3.7cm^3$, respectively, in comparison to that without using the PSCB. The gamma pass rates of the concave and convex plans were 95% and 98%, respectively. A new procedure of the fabrication of a PSCB is developed using a 3DP. We confirm the usefulness and dosimetric accuracy of the 3D-PSCB for the clinical use. Thus, rapidly advancing 3DP technology is able to ease and expand clinical implementation of the PSCB.