• 전기학회논문지
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• 제64권6호
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• pp.900-911
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• 2015

In this paper, 3D face recognition model is designed by using Polynomial based RBFNN(Radial Basis Function Neural Network) and PNN(Polynomial Neural Network). Also recognition rate is performed by this model. In existing 2D face recognition model, the degradation of recognition rate may occur in external environments such as face features using a brightness of the video. So 3D face recognition is performed by using 3D scanner for improving disadvantage of 2D face recognition. In the preprocessing part, obtained 3D face images for the variation of each pose are changed as front image by using pose compensation. The depth data of face image shape is extracted by using Multiple point signature. And whole area of face depth information is obtained by using the tip of a nose as a reference point. Parameter optimization is carried out with the aid of both ABC(Artificial Bee Colony) and PSO(Particle Swarm Optimization) for effective training and recognition. Experimental data for face recognition is built up by the face images of students and researchers in IC&CI Lab of Suwon University. By using the images of 3D face extracted in IC&CI Lab. the performance of 3D face recognition is evaluated and compared according to two types of models as well as point signature method based on two kinds of depth data information.

• 한국콘텐츠학회논문지
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• 제18권10호
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• pp.431-442
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• 2018

2차원 바코드인 QR코드는 사진, 동영상, 지도, 명함 등 다양한 정보를 더 편리하게 담아낼 수 있다. 현재 스마트 폰의 보급으로 QR코드는 다양한 인쇄 매체에 인쇄하여 연결된 인터넷 정보를 손쉽게 검색하는 수단으로 활용되고 있다. 그러나 QR코드는 정보보안이 용이하지 않아, 결재시스템에 활용하기에는 매우 제한적이다. 본 논문에서는 기존의 QR코드와 컬러 도안을 결합하여 새로운 코드를 설계하여, 제품 인증 시스템이 요구되는 분야에 활용할 수 있는 방안을 제안한다. 제안한 방법은 CMYK 컬러 모델로 인쇄된 정품은 전자기기에서 RGB 컬러 모델로 캡처되며, 이때 컬러의 왜곡이 발생하게 되는데, 이를 컬러 매트릭스를 통해 측정하고, 통계 특성에 기초한 정품 인증시스템을 제안한다. 다양한 종류의 컬러 코드를 통해 본 논문에서 제안한 방법이 제품 인증 시스템에 효과적으로 사용될 수 있음을 보인다.

• The Journal of Advanced Prosthodontics
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• 제10권5호
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• pp.367-373
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• 2018

PURPOSE. To evaluate the fit of a crown produced based on a 3D printed model and to investigate its clinical applicability. MATERIALS AND METHODS. A master die was fabricated with epoxy. Stone dies were fabricated from conventional impressions (Conventional stone die group: CS, n=10). Digital virtual dies were fabricated by making digital impressions (Digital Virtual die group: VD, n=10). 3D data obtained from the digital impression was used to fabricate 3D printed models (DLP die group: DD, n=10, PolyJet die group: PD, n=10). A total of 40 crowns were fabricated with a milling machine, based on CS, VD, DD and PD. The inner surface of all crowns was superimposed with the master die files by the "Best-fit alignment" method using the analysis software. One-way and 2-way ANOVA were performed to identify significant differences among the groups and areas and their interactive effects (${\alpha}=.05$). Tukey's HSD was used for post-hoc analysis. RESULTS. One-way ANOVA results revealed a significantly higher RMS value in the 3D printed models (DD and PD) than in the CS and DV. The RMS values of PD were the largest among the four groups. Statistically significant differences among groups (P<.001) and between areas (P<.001) were further revealed by 2-way ANOVA. CONCLUSION. Although the fit of crowns fabricated based on the 3D printed models (DD and PD) was inferior to that of crowns prepared with CS and DV, the values of all four groups were within the clinically acceptable range (<$120{\mu}m$).

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2007년도 제28회 춘계학술대회논문집
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• pp.265-271
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• 2007

본 연구에서는 자체 설계한 소형 초음속 풍동을 이용하여 초음속 충동형 터빈의 유동 특성을 살펴보았다. 터빈 익렬 위치에 따른 초음속 터빈 내부의 유동 특성을 파악하고 확산 손실이 발생하는 특성을 알아보기 위해 터빈 익렬 위치를 조절해가며 2차원 초음속 노즐과 익렬을 조합하여 실험을 실시하였다. 터빈 익렬 내부의 유동 가시화를 위해 Z-type 슐리렌(Schlieren) 시스템을 사용하였으며 압력변환기와 압력스캐너를 이용하여 터빈 익렬 내부의 정압력과 익렬 후류의 전압력을 측정하였다. 이러한 일련의 실험을 통해 충격파를 포함한 복잡한 유동 형태와 유동박리, 충격파-경계층 상호작용 등을 관찰할 수 있었으며 터빈 익렬 위치에 따른 터빈 내부의 유동 특성을 파악할 수 있었다.

• 한국의류학회지
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• 제29권11호
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• pp.1507-1519
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• 2005

The purpose of this study was to compare two methods of measuring body surface area (BSA). The BSA of Korean adults was measured using both three-dimensional (3D) scanning and an alginate method. Two males (one overweight and one lean) and one overweight female participated as subjects. The results were as follows: First, the 3D scanned BSA of all three subjects was smaller than the BSA measured using the alginate method by as much as $6-14\%$. The difference in methods was greater in the overweight participants than in the lean subject. Second, the results comparing the BSA obtained using these two methods and the BSA estimated by 10 previously developed formulas, showed that the 3D scanned BSA was the smallest among the 12 BSAs. Third, in comparing the regional differences between these two methods, the regional BSA of the lean subject (male 2) did not show any significant difference, but the overweight subjects (male 1, female 1) showed a significant difference. Forth, the biggest difference in regional BSA obtained through these two methods was in the hand, for all three subjects. The 3D scanned hand surface area was smaller than the hand surface area measured by the alginate method by as much as $24-34\%$. Fifth, in the percentage of regional BSA, there was no significant difference in these two methods. The reasons for the underestimation in the 3D scanning might be because: 1) the 3D scanner can not recognize the folding and shading of body parts, such as the finger, toe, ear, armpit, crotch and breast, 2) 3D patching and smoothing processes depend on researchers. However, the 3D scanning method is applicable to the estimation of the entire BSA, if the surface area of the hands is known, and the participant is not overweight.

• The Journal of Advanced Prosthodontics
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• 제14권1호
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• pp.22-31
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• 2022

PURPOSE. The purpose of this study was to investigate the misfit and screw preload at the implant abutment connection of implant supported fixed dental prosthesis with cantilever (ICFDP) manufactured using different digital manufacturing techniques and to compare the screw preload before and after cyclic loading. MATERIALS AND METHODS. Mandibular jaw model with four intra-foraminal implants was scanned using digital scanner. Stereolithography file was used to design a framework with nonengaging (NE) abutments and 10 mm cantilever distal to one terminal implant. Five frameworks were constructed using combined digital-conventional techniques (CAD-cast), and five frameworks were constructed using three-dimensional printing (3DP). Additional CAD-cast framework was constructed in a way that ensures passive fit (PF) to use as control. Scanning electron microscope (SEM) measured the implant abutment connection misfit. Sixty screws were used on the corresponding frameworks. Screws were torqued and pre-cyclic loading reverse torque value (RTV) was recorded. Frameworks were subjected to 200,000 loading cycles with a loading point 9 mm from the center of terminal implants adjacent to the cantilever and post-cyclic loading RTVs were recorded. RESULTS. Microscopic readings showed significant differences between frameworks. PF demonstrated the lowest measurements of 16.04 (2.6) ㎛ while CAD-cast demonstrated the highest measurements of 29.2 (3.1) ㎛. In all groups, RTVs were significantly lower than the applied torque. Post-cyclic loading RTV was significantly lower than pre-cyclic loading RTV in PF and 3DP frameworks. Differences in RTVs between the three manufacturing techniques were insignificant. CONCLUSION. Although CAD-cast and three-dimensionally printed (3DP) both produce frameworks with clinically acceptable misfit, 3DP might not be the technique of choice for maintaining screw's preload stability under an aggressive loading situation.

• 대한치과교정학회지
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• 제47권2호
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• pp.108-117
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• 2017

Objective: To investigate the effects of frontal facial type (FFT) and sex on preferred chin projection (CP) in three-dimensional (3D) facial images. Methods: Six 3D facial images were acquired using a 3D facial scanner (euryprosopic [Eury-FFT], mesoprosopic [Meso-FFT], and leptoprosopic [Lepto-FFT] for each sex). After normal CP in each 3D facial image was set to $10^{\circ}$ of the facial profile angle (glabella-subnasale-pogonion), CPs were morphed by gradations of $2^{\circ}$ from normal (moderately protrusive [$6^{\circ}$], slightly protrusive [$8^{\circ}$], slightly retrusive [$12^{\circ}$], and moderately retrusive [$14^{\circ}$]). Seventy-five dental students (48 men and 27 women) were asked to rate the CPs ($6^{\circ}$, $8^{\circ}$, $10^{\circ}$, $12^{\circ}$, and $14^{\circ}$) from the most to least preferred in each 3D image. Statistical analyses included the Kolmogorov-Smirnov test, Kruskal-Wallis test, and Bonferroni correction. Results: No significant difference was observed in the distribution of preferred CP in the same FFT between male and female evaluators. In Meso-FFT, the normal CP was the most preferred without any sex difference. However, in Eury-FFT, the slightly protrusive CP was favored in male 3D images, but the normal CP was preferred in female 3D images. In Lepto-FFT, the normal CP was favored in male 3D images, whereas the slightly retrusive CP was favored in female 3D images. The mean preferred CP angle differed significantly according to FFT (Eury-FFT: male, $8.7^{\circ}$, female, $9.9^{\circ}$; Meso-FFT: male, $9.8^{\circ}$, female, $10.7^{\circ}$; Lepto-FFT: male, $10.8^{\circ}$, female, $11.4^{\circ}$; p < 0.001). Conclusions: Our findings might serve as guidelines for setting the preferred CP according to FFT and sex.

• 대한치과보철학회지
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• 제53권2호
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• pp.105-110
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• 2015

목적: 새롭게 개발된 인상채득이 가능한 치유지대주를 이용한 인상채득과 기존의 임프레션 코핑을 이용한 인상채득을 3차원적으로 비교함으로써 개발된 시스템의 정확성을 평가하였다. 재료 및 방법: 10명의 환자에서 구치부에 임플란트(SuperLine; Dentium, Seoul, Korea)를 식립 후 치유지대주(MyHealing; Raphabio Co., Seoul, Korea)를 연결하였다. 식립 3개월 후 보철물 제작을 위한 인상채득시 인상채득이 가능한 치유지대주를 이용한 transfer 방식과 기존의 인상용 코핑을 이용한 pick-up 방식으로 두 번 인상채득 후 각각 주모형을 제작하였다. 맞춤형 보철 지대주(Myplant; Raphabio Co., Seoul, Korea)를 제작하고 각각의 주모형에 체결 후 치과용 스캐너(Scanner S600; Zirkonzahn, South Tyrol, Italy)로 가상의 모형을 형성하였다. 3차원 분석 프로그램(Geomagic Qualify 12; Geomagic, Morrisville, NC, USA)을 이용하여 두 개의 가상의 모형을 중첩하여 지대주의 위치와 기울기의 차이를 분석하였다. 측정값은 Kruskal Wallis과 Mann-Whitney U test 방법을 통해 분석하였고, 유의수준은 0.05 로 설정하였다. 결과: 두 가지 인상법에 따른 지대주의 위치는 근원심 방향에서 0.032 mm, 협설측 방향에서 0.029 mm, 상하 방향에서 0.023 mm의 차이를 보였다. 기울기는 근원심 방향에서 $0.755^{\circ}$, 협설측 방향에서 $1.275^{\circ}$, 상하 방향에서 $0.420^{\circ}$의 차이를 보였다. 결론: 인상채득이 가능한 치유지대주를 이용한 인상채득 방식은 기존의 전통적인 인상용 코핑을 이용한 방식과 비교 시 0.032 mm 이내의 차이를 보였고 기존 논문과의 비교 시 유사한 수치이다.

• 한국측량학회지
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• 제31권2호
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• pp.111-119
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• 2013

항공 라이다로부터 획득한 대용량의 3차원 점 데이터로부터 대상 물체의 윤곽정보를 추출하는 것은 데이터 처리 과정에서 필수적이며 기반적인 기술 중의 하나이다. 특히 인공 구조물인 건물은 복잡한 현대 도시를 구성하는 주요 구조물이며 그 형태가 명확하기에 윤곽 정보의 추출 과정이 더욱 중요하다 할 수 있다. 본 연구에서는 항공 라이다를 이용하여 얻어진 건물을 구성하는 3차원 점 데이터로부터 건물의 윤곽정보를 추출하기 위하여 점 데이터의 기하정보만을 이용한 확장 카이(${\chi}$-Chi) 알고리즘을 제안한다. 제안된 알고리즘은 임의의 점군을 델로니(Delaunay) 삼각망으로 구성하고 특정 조건을 만족하는 변(edge)를 제거하는 과정을 통하여 구현된다. 덧붙여, 전체적인 추출과정의 효율화를 위해서 델로니 삼각망의 구성을 스윕헐 알고리즘을 적용하여 수행하였다. 본 연구에서 제안하는 확장 카이 알고리즘의 성능을 확인하기 위하여 본 연구와 같은 목적으로 개발된 인케이싱 폴리곤 제작 알고리즘과 알파 쉐이프 알고리즘을 비교하였고 기 제작된 건물의 도화정보를 이용하여 윤곽정보 추출의 정확도를 비교하였다. 실험결과, 본 연구에서 제안한 알고리즘은 기존의 알고리즘들보다 윤곽정보 추출 속도 및 정확도가 향상됨을 확인하였다.

• The Journal of Advanced Prosthodontics
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• 제10권5호
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• pp.335-339
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• 2018

PURPOSE. The purpose of the present study was to compare scanning trueness and precision between an abutment impression and a stone model according to dental computer-aided design/computer-aided manufacturing (CAD/CAM) evaluation standards. MATERIALS AND METHODS. To evaluate trueness, the abutment impression and stone model were scanned to obtain the first 3-dimensional (3-D) stereolithography (STL) file. Next, the abutment impression or stone model was removed from the scanner and re-fixed on the table; scanning was then repeated so that 11 files were obtained for each scan type. To evaluate precision, the abutment impression or stone model was scanned to obtain the first 3-D STL file. Without moving it, scanning was performed 10 more times, so that 11 files were obtained for each scan type. By superimposing the first scanned STL file onto the other STL files one by one, 10 color-difference maps and reports were obtained; i.e., 10 experimental scans per type. The independent t-test was used to compare root mean square (RMS) data between the groups (${\alpha}=.05$). RESULTS. The $RMS{\pm}SD$ values of scanning trueness of the abutment impression and stone model were $22.4{\pm}4.4$ and $17.4{\pm}3.5{\mu}m$, respectively (P<.012). The $RMS{\pm}SD$ values of scanning precision of the abutment impression and stone model were $16.4{\pm}2.9$ and $14.6{\pm}1.6{\mu}m$, respectively (P=.108). CONCLUSION. There was a significant difference in scanning trueness between the abutment impression and stone model, as evaluated according to dental CAD/CAM standards. However, all scans showed high trueness and precision.