• 대한치과교정학회지
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• 제46권3호
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• pp.129-136
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• 2016

Objective: To investigate the dimensional accuracy of digital dental models obtained from the dental cone-beam computed tomography (CBCT) scan of alginate impressions according to the time elapse when the impressions are stored under ambient conditions. Methods: Alginate impressions were obtained from 20 adults using 3 different alginate materials, 2 traditional alginate materials (Alginoplast and Cavex Impressional) and 1 extended-pour alginate material (Cavex ColorChange). The impressions were stored under ambient conditions, and scanned by CBCT immediately after the impressions were taken, and then at 1 hour intervals for 6 hours. After reconstructing three-dimensional digital dental models, the models were measured and the data were analyzed to determine dimensional changes according to the elapsed time. The changes within the measurement error were regarded as clinically acceptable in this study. Results: All measurements showed a decreasing tendency with an increase in the elapsed time after the impressions. Although the extended-pour alginate exhibited a less decreasing tendency than the other 2 materials, there were no statistically significant differences between the materials. Changes above the measurement error occurred between the time points of 3 and 4 hours after the impressions. Conclusions: The results of this study indicate that digital dental models can be obtained simply from a CBCT scan of alginate impressions without sending them to a remote laboratory. However, when the impressions are not stored under special conditions, they should be scanned immediately, or at least within 2 to 3 hours after the impressions are taken.

• 한국산학기술학회논문지
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• 제15권5호
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• pp.3007-3013
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• 2014

본 연구의 목적은 블루 LED 기반의 치과용 스캐너를 이용하여 제작된 3차원 디지털 모형의 정확도를 평가하는 것이다. 본 연구를 위하여 20개의 동일한 석고 모형 제작 후 블루 LED기반의 치과용 스캐너를 이용하여 석고 모형과 동일한 20개의 3차원 디지털 모형을 제작하였다. 정확도를 평가하기 위해 두 집단의 모형을 대상으로 6개의 계측 거리를 지정한 후 측정하였다. 통계분석은 비모수 검정법인 윌콕슨 순위 합 검정법을 이용하여 비교 분석하였다(제1종 오류수준=0.05). 비록 모든 부위에서 디지털 모형이 석고 모형보다 작은 것으로 분석되었으나(p<0.05), 임상적 허용 수치를 벗어나지 않았다.

• 대한소아치과학회지
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• 제51권1호
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• pp.55-65
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• 2024

This study aimed to assess the accuracy of tooth widths, intermolar widths, and arch lengths acquired through two intraoral scanners, including iTero Element Plus Series (Align Technology, Santa Clara, CA, USA) and Trios 4 (3Shape, Copenhagen, Denmark), specifically on mixed dentition. A total of 30 subjects were divided into 2 groups, each undergoing both alginate impressions and intraoral scanning using either the iTero or Trios scanner. The plaster models were measured with a caliper, while the digital models were measured virtually. In the iTero group, all tooth width measurements exhibited differences compared to the plaster values, except for maxillary left lateral incisors (p = 0.179), mandibular right (p = 0.285), and left (p = 0.073) central incisors. The Trios group did not display significant differences in any of the tooth width measurements. Intermolar width comparisons for both groups indicated differences, except for mandibular primary canine to primary canine values (p = 0.426) in the iTero group. Regarding arch length, the mandibular anterior, maxillary right, and left arch lengths in the iTero group demonstrated larger caliper values than those of iTero. Conversely, in the Trios group, all parameters showed smaller caliper values, especially in upper anterior, maxillary right, mandibular right, and mandibular left arch lengths with significance (p = 0.027, 0.007, 0.003, and 0.047, respectively). Despite the differences between the two groups, digital models might be clinically suitable alternatives for plaster models. Pediatric dentists should carefully assess these differences, as a comprehensive evaluation would result in precise orthodontic treatment planning and favorable outcomes for young patients with mixed dentition.

• ETRI Journal
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• 제25권6호
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• pp.423-436
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• 2003

This paper describes our design of a contents distribution framework that supports transparent distribution of digital contents on the Internet as well as copyright protection of participants in the contents distribution value chain. Copyright protection must ensure that participants in the distribution channel get the royalties due to them and that purchasers use the contents according to usage rules. It must also prevent illegal draining of digital contents. To design a contents distribution framework satisfying the above requirements, we first present four digital contents distribution models. On the basis of the suggested distribution models, we designed a contract system for distribution of royalties among participants in the contents distribution channel, a license mechanism for enforcement of contents usage to purchasers, and both a packaging mechanism and a secure client system for prevention of illegal draining of digital contents.

• 한국안전학회지
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• 제22권3호
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• pp.81-87
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• 2007

In this study digital human models of ship construction tasks using modeling & simulation were constructed and human models' activities through human activity analysis were evaluated. Human Factors experts analyzed the actual workers' tasks using the same technique used in human activity analysis at the same time. The main objective of this study is to check a possibility of applying digital human modeling technique to ship construction tasks that are mostly non-standardized(not uniformed) whereas most applications of digital human modeling technique have been applied to standardized tasks. We evaluated postures of both real workers and digital humans by RULA. It turned out that the final scores of RULA evaluation on real workers are the same as the RULA scores for digital humans. However, there were differences of RULA detail scores between real workers and digital humans in the several processes related with the wrist twist and deviations. Those differences are considered to be resulted from the error in the on-site measuring worker's body dimension which could be reduced by accurate tools to correct data for body dimension and digital real drawings for facilities. The results showed possibility of application of digital human modeling and ergonomic analysis on informal work operations as well as formal operations in the shipbuilding industry.

• 대한치과기공학회지
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• 제36권1호
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• pp.17-23
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• 2014

Purpose: The purpose of this study was to analyze and compare the relative accuracy of digitized stone models of lower full arch, using two different scanning system. Methods: Replica stone models(N=20) were produced from lower arch acrylic model. Twenty digital models were made with the white light and blue LED($Medit^{(R)}$, Korea) scanner. Two-dimensional distance between the landmarks were measured on the Delcam $CopyCAD^{(R)}$(Delcam plc, UK). Independent samples t-test was applied for comparison of the groups. All statistical analyses were performed using the SPSS software package(Statistical Package for Social Sciences for Windows, version 12.0). Results: The absolute disagreement between measurements made directly on the two different scanner-based dental digital models was 0.02~0.04mm, and was not statistically significant(P>0.05). Conclusion: The precision of the blue LED optical scanner was comparable with the digitization device, and relative accuracy was similar. However, there still is room for improvement and further standardization of dental CAD technologies.

• 디지털산업정보학회논문지
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• 제20권1호
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• pp.31-45
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• 2024

The purpose of this study is to explain employment factors in the software field. For it, the Graduates Occupational Mobility Survey by the Korea employment information service is used. This paper proposes employment models in the software field using machine learning. Then, it explains employment factors of the models using explainable artificial intelligence. The models focus on both university graduates and vocational college graduates. Our works explain and interpret both black box model and glass box model. The SHAP and EBM explanation are used to interpret black box model and glass box model, respectively. The results describes that positive employment impact factors are major, vocational education and training, employment preparation setting semester, and intern experience in the employment models. This study provides a job preparation guide to universitiy and vocational college students that want to work in software field.

• 대한치과보철학회지
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• 제53권2호
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• pp.111-119
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• 2015

목적: 인상재와 석고모형을 사용하지 않고 디지털 영상 만을 사용하여 제작된 수술가이드를 이용한 치과 임플란트 수술의 정확도를 평가하고자 하였다. 재료 및 방법: 상하악 부분 무치악 모델 6개 세트를 본 연구에 사용하였다. 모델을 환자 구강구조로 간주하고 부분 무치악 모델을 Trios 구강스캐너로 디지털 인상을 채득하였다. 수술가이드의 정확도 평가를 위해 제작된 Reference plate를 모델의 교합면에 고정한 상태로 CBCT를 촬영하였다. CBCT에서 얻은 영상과 디지털 인상에서 얻은 영상을 정합하고 정합한 영상에서 임플란트 식립위치를 진단하고 수술가이드를 디자인하였다. 제작된 수술가이드를 이용하여 부분 무치악 모델에서 임플란트를 식립하였다. 시술 후, 시술 전과 동일한 방법으로 CBCT를 촬영하여 시술 전 컴퓨터 소프트웨어에서 측정한 수치와 시술 후 CBCT촬영하여 소프트웨어상에서 측정한 시술 후 수치 사이 차이점을 비교하였다. 결과: 평균거리오차가 임플란트 상단 X축에서 0.27 mm, Y축에서 0.29 mm 였으며, 임플란트 하단(Apex)부위에서는 X축에서 0.11 mm, Y축에서 0.14 mm 평균각도오차가 X축에서 $0.26^{\circ}$, Y축에서 $0.26^{\circ}$ 였다. 평균수직오차는 +0.44 mm로 시술 전 계획한 높이보다 평균 0.44 mm 더 위로 임플란트가 식립되었다. 결론: 본 연구의 결과는 인상재와 석고모형을 사용하지 않고 디지털 영상 만을 사용하여 제작된 수술가이드를 사용하여 임플란트를 시술할 경우 계획한 임플란트 식립 위치와 방향으로 높은 정확도를 가지고 임플란트를 식립할 수 있음을 보여 주었다.

• 대한소아치과학회지
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• 제49권1호
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• pp.14-24
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• 2022

이 연구의 목적은 디지털 치열 모형에서 치아 폭경, 볼튼 비율, 수평 피개, 수직 피개를 포함한 교정적 측정의 타당성을 확인하는 것이다. 만 12 - 18세의 환자를 대상으로 세가지 형태의 치열 모형을 획득하였다. 기존의 석고 모형을 형성하였고, DOF freedom HD 모형 스캐너를 통해 디지털 모형으로 변환하였다. 그리고 CS3600 구강 스캐너로 디지털 모형을 형성하였다. 각 모형에서 측정 시행 후, 급내 상관 계수를 통해 계측의 신뢰성과 재현성을 확인하였으며, 대응 표본 t 검정을 사용하여 타당성을 평가하였다. 결과적으로 모든 군에서 급내 상관계수는 0.750을 초과하여 연구자 내 신뢰성과 연구자 간 재현성이 있음을 확인하였다. 모형 스캔한 군은 전체 및 전치 볼튼 비율, 수평 및 수직 피개에서 타당성을 보였다. 구강 스캔한 군은 전치 볼튼 비율, 수평 피개에서 타당성을 보였다. 구강 스캔한 디지털 모형을 이용한 계측은 인상 채득에 어려움이 있는 소아 청소년에게 고려할 수 있는 대안이다. 하지만 임상에서 이를 교정적 분석에 이용할 경우 오차를 고려한 적용이 필요하다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 가을학술발표대회논문집
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• pp.239-240
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• 2023

Construction site management involves overseeing tasks from the construction phase to the maintenance stage, and digitalization of construction sites is necessary for digital construction site management. In this study, we aim to conduct research on object recognition at construction sites using drones. Images of construction sites captured by drones are reconstructed into BIM (Building Information Modeling) models, and objects are recognized after partially rendering the models using artificial intelligence. For the photorealistic rendering of the BIM models, both traditional filtering techniques and the generative adversarial network (GAN) model were used, while the YOLO (You Only Look Once) model was employed for object recognition. This study is expected to provide insights into the research direction of digital construction site management and help assess the potential and future value of introducing artificial intelligence in the construction industry.