• 한국지능시스템학회논문지
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• 제14권7호
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• pp.871-877
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• 2004

본 논문은 맞춤형 신발제작을 위하여 신발에 필요한 화형제작용 데이터를 3차원 측정 장치를 통해 획득한 발의 형상을 인공지능 기법을 기반으로 하는 최적화된 형상을 복원하는 방법을 제시하고자 한다. 본 연구를 위해 개발된 시스템은 PC를 기반으로 하는 기존의 3차원측정 방식을 이용하여 상, 하, 좌, 우로 각각 장착된8대의 CCD 카메라와 4대의 laser를 통해 화형 및 발의 형상 데이터를 획득한다. 획득된 데이터들은 인공지능 기법을 이용한 영상처리 알고리즘으로 처리되며, 처리 결과는 기존의 지능 기법을 도입하지 않은 시스템에 비해 노이즈제거 특성이 향상되었고, 후처리과정을 간소화 할 수 있다. 따라서 본 논문에서는 3차원 측정을 위해 하드웨어적인 부분과 이를 제어하기 위한 소프트웨어 및 GUI로 전체 시스템을 구성하고, 본 논문에서는 데이터 처리용 소프트웨어에서 입력영상의 전처리 과정 중 영상의 이진화 단계에서 임계값을 결정하기 위하여 신경망을 사용하였으며, 이에 대한 결과를 제시하고자 한다.

• 대한치과기공학회지
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• 제46권1호
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• pp.8-14
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• 2024

Purpose: This study compares the deformation of traditional resin dentures to resin dentures printed with digital light processing (DLP). Methods: Eleven edentulous research models were developed. Ten of them were made with traditional resin dentures. The remaining one was prepared for scanning and 3D (three-dimensional) printing. Ten traditional resin dentures were made, with the remaining artificial teeth created using 3D software and a DLP printer. Traditional resin dentures, 3D printed resin denture artificial teeth, and a denture base with artificial teeth were all cleaned simultaneously in an ultrasonic cleaner for 3 minutes. Three groups were assigned four artificial tooth measurement points, which were then measured with digital calipers. The measured data was analyzed using descriptive statistics. The significance test was conducted using a nonparametric test Kruskal-Wallis test due to the small number of specimens (α=0.05). Results: The traditional resin dentures had the lowest strain rate at -0.04%, while the group that manufactured only artificial teeth had the highest strain rate at -0.09%. However, no statistically significant difference was observed between the 3 groups (p>0.05). Conclusion: During ultraviolet-type ultrasonic cleaning, traditional resin dentures (TD group) and denture base with artificial teeth made of DLP (DD group) demonstrated stable durability, whereas the artificial teeth made of DLP (AD group) with only artificial teeth did not show a good deformation rate.

• 항공우주기술
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• 제3권1호
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• pp.126-133
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• 2004

사진측량법(Photogrammetry)는 서로 다른 촬영각을 가지는 다수의 2차원 이미지로부터 대상물의 정밀한 3차원 형상을 얻어내는 기법이다. 본 연구에서는 사진측량법을 활용하여 다목적 실용위성 2호 비행모델 하부 탑재체 플랫폼(Low Payload Platform)의 고해상도 카메라 접합면에 대한 편평도(Flatness) 측정 작업을 수행하였으며, 정밀하게 교정된 2개의 스케일바(Scale Bar)를 사용하여 절대적인 길이 값을 3차원 모델에 부과함과 동시에 측정정확도를 계산하여 내었다. 또한 측정된 편평도 결과는 고해상도 카메라 납품 업체에서 제시한 편평도 요구조건과 비교되었다.

• Journal of Magnetics
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• 제20권1호
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• pp.40-46
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• 2015

This study investigated the accuracy of magnetic resonance angiography (MRA) and computed tomography angiography (CTA) in terms of reflecting the actual vascular length. Three-dimensional time of flight (3D TOF) MRA, 3D contrast-enhanced (CE) MRA, volume-rendering after CTA and maximum intensity projection were investigated using a flow model phantom with a diameter of 2.11 mm and area of $0.26cm^2$. 1.5 and 3.0 Tesla devices were used for 3D TOF MRA and 3D CE MRA. CTA was investigated using 16 and 64 channel CT scanners, and the images were transmitted and reconstructed by volume-rendering and maximum intensity projection, followed by conduit length measurement as described above. The smallest 3D TOF MRA measure was $2.51{\pm}0.12mm$ with a flow velocity of 40 cm/s using the 3.0 Tesla apparatus, and $2.57{\pm}0.07mm$ with a velocity of 71.5 cm/s using the 1.5 Tesla apparatus; both images were magnified from the actual measurement of 2.11 mm. The measurement with the 16 channel CT scanner was smaller ($3.83{\pm}0.37mm$) than the reconstructed image on maximum intensity projection. The images from CTA from examination apparatus and reconstruction technique were all larger than the actual measurement.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제42권
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• pp.17.1-17.11
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• 2020

Background: To evaluate the facial asymmetry, three-dimensional computed tomography (3D-CT) has been used widely. This study proposed a method to quantify facial asymmetry based on 3D-CT. Methods: The normal standard group consisted of twenty-five male subjects who had a balanced face and normal occlusion. Five anatomical landmarks were selected as reference points and ten anatomical landmarks were selected as measurement points to evaluate facial asymmetry. The formula of facial asymmetry index was designed by using the distances between the landmarks. The index value on a specific landmark indicated zero when the landmarks were located on the three-dimensional symmetric position. As the asymmetry of landmarks increased, the value of facial asymmetry index increased. For ten anatomical landmarks, the mean value of facial asymmetry index on each landmark was obtained in the normal standard group. Facial asymmetry index was applied to the patients who had undergone orthognathic surgery. Preoperative facial asymmetry and postoperative improvement were evaluated. Results: The reference facial asymmetry index on each landmark in the normal standard group was from 1.77 to 3.38. A polygonal chart was drawn to visualize the degree of asymmetry. In three patients who had undergone orthognathic surgery, it was checked that the method of facial asymmetry index showed the preoperative facial asymmetry and the postoperative improvement well. Conclusions: The current new facial asymmetry index could efficiently quantify the degree of facial asymmetry from 3D-CT. This method could be used as an evaluation standard for facial asymmetry analysis.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2018년도 춘계학술대회
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• pp.612-614
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• 2018

현재 사진으로 모델링데이터를 획득 할 수 있는 기술이 등장하고 있다. 다양한 조형물, 건축 및 캐릭터에 대한 3D 모델링 제작은 많은 시간을 투자하여 제작되고 있다. 콘텐츠산업에서도 많이 활용되고 있는 3D 모델링 제작방식은 정확한 측정 도구 없이 스케치된 도면을 중심으로 제작자의 직감적 감각을 이용하여 모델링데이터를 생성하고 있는 것도 사실이다. 최근에는 사진정보의 조합으로 조형물의 정확한 3차원 데이터를 생성하고 재구성하여 기존 디자인의 변형이나 수정이 용이하게 할 수 있는 기술이 발달하고 있다. 본 논문은 대상물에 대한 여러 장의 사진 데이터를 활용하여 정밀한 3차원 모델링 데이터를 생성하는 방법을 연구하고 이를 활용할 수 있는 방안을 제안한다.

• 대한치과기공학회지
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• 제44권4호
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• pp.126-131
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• 2022

Purpose: The purpose of this study is to evaluate the quality of dental fixed prostheses fabricated by 3DP (three-dimensional printing). Methods: Ten main models were prepared for the study. Ten specimens were printed by 3DP (3DP group). Ten specimens were fabricated by the lost wax technique and casting method to complete the control group (LWC group). The marginal fit was measured for 20 specimens. The measurement of marginal fit was performed using the silicon replica technique. Finally, the marginal fit of 10 specimens from each group was calculated. An independent sample t-test was run to see if the calculated averages for the two groups were mutually significant (α=0.05). Results: According to the experimental results, the mean marginal fit of the 3DP group was 71.9 ㎛, and the LWC group was 55.3 ㎛. The means of the two groups were found to be significantly different (p<0.001) in the results of the independent sample t-test. Conclusion: The marginal fit of fixed dental prostheses produced by 3DP technology was examined with values greater than those fabricated by traditional technology. However, as it appeared to be a value within the range of clinically acceptable range recommended by numerous studies, it was determined that clinical application would be feasible.

• 한국정밀공학회지
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• 제23권4호
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• pp.183-190
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• 2006

Digital 3D Real Object Duplication System (RODS) consists of 3D Scanner and Solid Freeform Fabrication System (SFFS). It is a device to make three-dimensional objects directly from the drawing or the scanning data. In this research, we developed an office type SFFS based on Three Dimensional Printing Process and an industrial SFFS using Dual Laser. An office type SFFS applied sliding mode control with sliding perturbation observer (SMCSPO) algorithm for control of this system. And we measured process variables about droplet diameter measurement and powder bed formation etc. through experiments. In case of industrial type SFFS, in order to develop more elaborate and speedy system for large objects than existing SLS process, this study applies a new Selective Dual-Laser Sintering (SDLS) process and 3-axis Dynamic Focusing Scanner for scanning large area instead of the existing f lens. In this process, the temperature has a great influence on sintering of the polymer. Also the laser parameters are considered like that laser beam power, scan speed, and scan spacing. Now, this study is in progress to evaluate the effect of experimental parameters on the sintering process.

• 대한공간정보학회지
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• 제17권4호
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• pp.95-103
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• 2009

전세계적으로 다양한 관측 센서 및 자료처리 기술개발을 통하여 현실 세계에 대한 3차원 공간정보 구축에 관한 관심이 높아지고 있으며, 사생활 침해 논란에도 불구하고 도시지역 곳곳에 설치된 CCTV가 교통관리나 범죄 예방 및 재난 모니터링을 위한 핵심 관측장비로서 활용되고 있다. 도시지역의 안전 확보와 각종 재난 예방을 위해 기구축된 3차원 공간정보에 CCTV 영상이나 비디오 자료를 연계시켜 유사시 발생한 상황을 실시간적으로 인터렉티브하게 파악하고 모니터링할 수 있는 감시 시스템의 필요성이 제기되고 있다. 따라서, 본 연구에서는 웹 가시화의 국제표준인 X3D를 기반으로 3차원 공간정보와 비디오 융합을 통하여 인터넷 상에서 실시간으로 인터렉티브하게 가시화할 수 있는 프로토타입 시스템을 개발하여 그 활용가능성을 제시하고자 하였다.

• 한국운동역학회지
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• 제15권2호
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• pp.83-92
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• 2005

Computer-assisted motional analysis is a popular method in biomechanical studies. Validation of the specific system and its measurement are fundamental to its application in the areas. Because the accuracy and consistency of a particular system provide the researchers with critical information to assist in making judgements regarding the degree to which inferences can be drawn from measurement data. The purpose of this study was to assess the accuracy and consistency of the Kwon3D motion analysis system. Validation parameters were five lengths from eight landmarkers in combination with the DLT reconstruction error values, digitizing monitor resolutions, and numbers of control points. With the best setting, Kwon3D's estimations of 260cm, 200cm, 140cm, 100cm, and 20cm were $260.33{\pm}.688cm$, $199.98{\pm}.625cm$, $139.89{\pm}.537cm$, $99.75{\pm}.466cm$, $20.08{\pm}.114$, respectively. There was no significant DLT error value difference between two monitor resolutions, but 0.27cm significant difference in 260cm estimation. There were significant differences in 260cm and 200cm estimations between with 33-control-point DLT error and with 17-control-point DLT error, but no in 140cm, 100cm, and 20cm estimations. Test-retest results showed that Kwon3D measurements were highly consistent with reliability coefficients alpha of .9263 and above.