• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1975-1980
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• 2004

The three-dimensional flow in a turbine nozzle guide vane passage causes large secondary loss through the passage and increased heat transfer on the blade surface. In order to reduce or control these secondary flows, a linear cascade with a contoured endwall configuration was used and changes in the three-dimensional flow field were analyzed and discussed. Measurements of secondary flow velocity and total pressure loss within the passage have been performed by means of five-hole probes. The investigation was carried out at fixed exit Reynolds number of $4.0{\times}10^5$. The objective of this study is to document the development of the three-dimensional flow in a turbine nozzle guide vane cascade with modified endwall. The results show that the development of passage vortex and cross flow in the cascade composed of one flat and one contoured endwalls are affected by the flow acceleration which occurs in contoured endwall side. The overall loss is reduced near the flat endwall rather than contoured endwall.

• 복식문화연구
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• 제15권2호
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• pp.252-264
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• 2007

The purpose of this study was to compare two analytical methods classifying foot shape. The methods compared were cluster analysis method and foot index analysis method. This study defined the women's foot shape by these methods. 39 foot measurements which were automatically collected using the three dimensional foot scanner were analyzed. 203 Korean women in age 20s were participated in the anthropometric survey. Their foot shapes were classified into 5 foot types by cluster analysis: short & slim shape, flat shape, short & slender shape with slightly distorted toe, long and big shape, and short & wide shape. The foot measurements were also analyzed by the ratio of foot width and length. Five foot types that were classified by cluster analysis and three foot types that were classified by the foot index were compared. The comparison shows that cluster analysis precisely defined foot shapes. It was suggested that made-to-measure shoes making industry may adopt the foot shape analysis method utilizing cluster analysis.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제34권1호
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• pp.17-25
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• 2012

Purpose: Recently, a three dimensional approach to hard and soft tissues of the maxillofacial area has been widely used. This study was to evaluate the reproducibility and accuracy of a stereocamera compared to actual measurement methods using a digital caliper and digitizer. Methods: The stereoscopies of 7 head dummies with different sizes and shapes were obtained using a Di3D system (Dimensional Imaging, Glasgow, UK) after marking reference points on facial areas. From the obtained stereoscopy, 10 measurements representing the width, height and depth of each of the facial sections of the dummy were measured twice using a three dimensional reverse engineering software program (RapidForm$^{TM}$ 2006, Inus, Seoul, Korea). The x, y, and z coordinates of each of the three dimensional measurements were obtained and distances between two points were calculated. All procedures were repeated twice. The actual measurement method was performed twice, directly on dummies, using a digital caliper and values were compared with the previously determined values. Results: The results were as follows. In the ANOVA analysis, there were no significant statistical differences among the three measurement methods. In the Bonferroni analysis, with adjustments applied for multiple comparisons, there was no difference between actual measurement methods using a digitizer and a digital caliper. However, there was some difference between using a stereocamera and actual measurement methods using a digitizer and a digital caliper in values of $Ex_{Rt}-Ex_{Lt}$, $En_{Rt}-En_{Lt}$, $Ala_{Rt}-Ala_{Lt}$, $Ch_{Rt}-Ch_{Lt}$, G-Pg', $Ala_{Rt}$-Prn, $Ala_{Rt}$-Prn. The mean value for technical error in measurement (TEM) in Di3D (0.98 mm) was slightly higher than for a digital caliper (0.17 mm) and a digitizer (0.30 mm). In an intraclass correlation coefficient (ICC) there were no significant differences among the three measurement methods, but the Di3D system with the stereocamera showed relatively lower reproducibility compared to actual measurement methods using a digitizer and a digital caliper. Conclusion: These results indicate that some complementary measures may be needed to improve accuracy and reproducibility in the Di3D system with stereocamera.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제21권2호
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• pp.174-188
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• 1999

통상적으로 사용되는 두부 계측 방사선기기를 이용하여 12개 건조 두개골의 중요한 방사선학적 계측점에 금속구를 위치시킨 후 정모와 측모 두부 방사선사진상을 촬영하고, 이를 바탕으로 얻어진 3차원 두부 방사선사진이 어느 정도의 정확도와 정밀도를 가지고 있는지 알아 보고자 하였다. 또한 이러한 입체 영상을 얻을수 있는 프로그램으로 실제 두명의 악변형증 환자에게 적용시켜 다음과 같은 결과를 얻었다. 1. Nasion relator 를 이용하여 두부위치를 고정한 상태에서 각각 촬영된 정모와 측모 두부 방사선사진으로 3차원 두부 방사선사진을 작성해 본 결과, 촬영시 두부의 위치적 변화에 따른 계측치의 차이는 $0.34{\pm}0.33mm$로 나타나 위치적 변화는 거의 없었다. 즉 동일한 두개골에 대한 3차원 계측치의 x, y, z 축상의 위치 편차가 거의 없었다. 2. 실계측치와 3차원 계측치의 차이는 평균 $1.47{\pm}1.45mm$ 크게 나타났으며 실측치에 대한 3차원 계측치의 확대율은 $100.24{\pm}4.68%$였으며, 차이가 평균보다 크게 나타난 일부 항목의 경우 측모 두부 방사선사진에서 정확한 위치를 잡아내기 어려웠던 계측점이 많았다. 즉, 3차원 계측거리가 실측치와 차이를 보이는 것은 방사선 사진촬영시 위치의 재현성과 관련된 것이라기 보다는 계측점의 식별이 더 크게 좌우된 것으로 보여진다. 3 정모와 측모 두부 방사선사진의 경우 필름과 평행한 시상면에 놓이지 않은 계측항목의 축소가 두드러졌으며 건조 두개골의 크기나 형태에 따라 필름간의 거리가 상이하였기 때문에 수평적, 수직적 확대율의 일관된 경향을 발견할 수 없었다. 실측치와의 차이는 정모 두부 방사선 사진이 $4.72{\pm}2.01mm$, 측모 두부 방사선사진이 $-5.22{\pm}3.36mm$로 나타났으며 수평 계측치보다 수직 계측치가 약간 더 실측치에 근접하는 것을 볼 수 있었다. 4. 실제 악교정수술 환자에게 적용해 본 결과, 계측항목의 수치적 분석보다는 악골자체의 이동량이나 변화의 정도, 비대칭의 분석등에 사용하는 것이 임상적으로 더 의의가 있으며 교정환자의 경우 정모와 측모 모두에서 명확히 나타나는 브라켓을 계측 기준점으로 할 경우 보다 정확한 계측을 할 수 있을 것으로 사료된다.

• 전자공학회논문지
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• 제53권4호
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• pp.117-128
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• 2016

대지의 접지 시스템 설치는 안전성과 전기 기기의 올바른 작동을 위해 필수적이며, 대지 파라미터, 특히 토양의 저항률은 대지 접지 시스템 설계에서 결정되어야 한다. 토양의 저항률을 측정하기 위한 가장 흔한 방법은 Wenner의 4전극 방법이 있으며, 이 방법은 1차원의 저항률을 얻기 위하여 가변 전극 간격을 갖는 큰 측정 세트가 요구되어 번거롭고, 시간소모가 많으며 비용이 많이 든다. 전기 저항 단층촬영법은 저비용이며 빠른 측정이 가능하다는 장점 때문에 토양의 저항률 분포를 추정하기 위해 적용될 수 있다. 전기 저항 단층은 관심지역에 놓인 전극에서 얻은 측정데이터를 사용하여 토양 저항률 분포를 특성화한다. 이때 전기 단층 촬영법의 역문제는 비선형성이 강하여 저항률 분포를 추정하기 위하여 Tikhonov 조정 방법을 갖는 반복적 Gauss-Newton 방법을 사용한다. 다양한 시뮬레이션을 수행하여 3차원 토양의 저항률 분포를 추정하는데 전기 저항 단층 촬영법은 유용한 성능을 제공하고 있음을 확인하였다.

• Imaging Science in Dentistry
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• 제51권3호
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• pp.279-290
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• 2021

Purpose: Using images in the facial image comparison process poses a challenge for forensic experts due to limitations such as the presence of facial expressions. The aims of this study were to analyze how morphometric changes in the face during a spontaneous smile influence the facial image comparison process and to evaluate the reproducibility of measurements obtained by digital stereophotogrammetry in these situations. Materials and Methods: Three examiners used digital stereophotogrammetry to obtain 3-dimensional images of the faces of 10 female participants(aged between 23 and 45 years). Photographs of the participants' faces were captured with their faces at rest (group 1) and with a spontaneous smile (group 2), resulting in a total of 60 3-dimensional images. The digital stereophotogrammetry device obtained the images with a 3.5-ms capture time, which prevented undesirable movements of the participants. Linear measurements between facial landmarks were made, in units of millimeters, and the data were subjected to multivariate and univariate statistical analyses using Pirouette^® version 4.5 (InfoMetrix Inc., Woodinville, WA, USA) and Microsoft Excel^® (Microsoft Corp., Redmond, WA, USA), respectively. Results: The measurements that most strongly influenced the separation of the groups were related to the labial/buccal region. In general, the data showed low standard deviations, which differed by less than 10% from the measured mean values, demonstrating that the digital stereophotogrammetry technique was reproducible. Conclusion: The impact of spontaneous smiles on the facial image comparison process should be considered, and digital stereophotogrammetry provided good reproducibility.

• Journal of Korean Dental Science
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• 제15권1호
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• pp.19-30
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• 2022

Purpose: The purpose of the study was to assess the validity of three-dimensional (3D) facial scan taken with facial scanner and digital photo wrapping on the cone-beam computed tomography (CBCT). Materials and Methods: Twenty-five patients had their CBCT scan, two-dimensional (2D) standardized frontal photographs and 3D facial scan obtained on the same day. The facial scans were taken with a facial scanner in an upright position. The 2D standardized frontal photographs were taken at a fixed distance from patients using a camera fixed to a cephalometric apparatus. The 2D integrated facial models were created using digital photo wrapping of frontal photographs on the corresponding CBCT images. The 3D integrated facial models were created using the integration process of 3D facial scans on the CBCT images. On the integrated facial models, sixteen soft tissue landmarks were identified, and the vertical, horizontal, oblique and angular distances between soft tissue landmarks were compared among the 2D facial models and 3D facial models, and CBCT images. Result: The results showed no significant differences of linear and angular measurements among CBCT images, 2D and 3D facial models except for Se-Sn vertical linear measurement which showed significant difference for the 3D facial models. The Bland-Altman plots showed that all measurements were within the limit of agreement. For 3D facial model, all Bland-Altman plots showed that systematic bias was less than 2.0 mm and 2.0° except for Se-Sn linear vertical measurement. For 2D facial model, the Bland-Altman plots of 6 out of 11 of the angular measurements showed systematic bias of more than 2.0°. Conclusion: The facial scan taken with facial scanner showed a clinically acceptable performance. The digital 2D photo wrapping has limitations in clinical use compared to 3D facial scans.

• Clinics in Shoulder and Elbow
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• 제23권2호
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• pp.71-79
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• 2020

Background: The glenoid version of the shoulder joint correlates with the stability of the glenohumeral joint and the clinical results of total shoulder arthroplasty. We sought to analyze and compare the glenoid version measured by traditional axial two-dimensional (2D) computed tomography (CT) and three-dimensional (3D) reconstructed images at different levels. Methods: A total of 30 cases, including 15 male and 15 female patients, who underwent 3D shoulder CT imaging was randomly selected and matched by sex consecutively at one hospital. The angular difference between the scapular body axis and 2D CT slice axis was measured. The glenoid version was assessed at three levels (midpoint, upper one-third, and center of the lower circle of the glenoid) using Friedman's method in the axial plane with 2D CT images and at the same level of three different transverse planes using a 3D reconstructed image. Results: The mean difference between the scapular body axis on the 3D reconstructed image and the 2D CT slice axis was 38.4°. At the level of the midpoint of the glenoid, the measurements were 1.7°±4.9° on the 2D CT images and -1.8°±4.1° in the 3D reconstructed image. At the level of the center of the lower circle, the measurements were 2.7°±5.2° on the 2D CT images and -0.5°±4.8° in the 3D reconstructed image. A statistically significant difference was found between the 2D CT and 3D reconstructed images at all three levels. Conclusions: The glenoid version is measured differently between axial 2D CT and 3D reconstructed images at three levels. Use of 3D reconstructed imaging can provide a more accurate glenoid version profile relative to 2D CT. The glenoid version is measured differently at different levels.

• 새물리
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• 제68권11호
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• pp.1275-1280
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• 2018

We demonstrated transmission direct phase-measuring deflectometry (DPMD) with a specular phase object having discontinuous surfaces by using two displays and a two-dimensional array detector for display and by recording the distorted fringe patterns. Three-dimensional (3D) information was obtained by calculating the height map directly from the phase information. We developed a mathematical model of the phase-height relationship in transmission DPMD. Unlike normal transmission deflectometry, this method supports height measurement directly from the phase. Compared with other 3D measurement techniques such as interferometry, this method has the advantages of being inexpensive and easy to implement.

• 대한치과교정학회지
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• 제35권3호
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• pp.163-173
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• 2005

본 연구는 안면비대칭 환자에서 경조직의 비대칭 정도와 연조직 비대칭 정도의 차이를 3차원적으로 밝히고자 시행되었다. 안면비대칭으로 보이는 성인 남녀 34명을 대상으로 두경부 전산단층사진을 촬영하고 3차원 입체영상으로 재구성한 후 기준평면에 대해 비대칭을 나타내는 5개의 계측항목을 경조직에 설정하고, 이에 대응하는 연조직 계측항목을 각각 설정한 후 3차원 계측을 시행하고 경조직과 연조직의 계측항목간 차이를 비교하였다. 이부편위측과 반대측간의 계측치 차이를 비교한 결과, 경조직과 연조직 모두에서 좌우측 계측치간에 통계적으로 유의한 차이가 관찰되었으며 경조직과 연조직의 비대칭 계측항목을 비교한 결과, 6개의 계측항목 모두에서 통계적으로 유의한 차이를 나타내었다. 이부편위를 나타내는 chin deviation, 하악지와 하악골체를 나타내는 frontal ramal inclination difference, frontal corpus inclination difference 항목은 경조직의 비대칭 정도에 비하여 연조직 비대칭 정도가 작게 나타난 반면, 입술경사를 나타내는 lip cheilion height difference, lip canting은 maxillary height difference, occlusal plane canting보다 크게 나타나 입술부위의 비대칭 정도는 하부 경조직의 비대칭 정도보다 큰 것으로 나타났다. 안면비대칭자에서 경조직과 연조직간 비대칭 정도 차이를 규명한 본 연구 결과는 안면비대칭 평가 시 경조직 외에 연조직 계측항목을 이용한 비대칭 분석도 필요함을 시사하였다.