• 대한두경부종양학회:학술대회논문집
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• 1999.12a
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• pp.259.1-259.1
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• 1999

• The Journal of Korean Academy of Prosthodontics
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• v.57 no.2
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• pp.102-109
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• 2019

Purpose: The purpose of this study was to evaluate the accuracy of three types of intraoral scanners and the accuracy of the single abutment and bridge abutment model. Materials and methods: In this study, a single abutment, and a bridge abutment with missing first molar was fabricated and set as the reference model. The reference model was scanned with an industrial three-dimensional scanner and set as reference scan data. The reference model was scanned five times using the three intraoral scanners (CS3600, CS3500, and EZIS PO). This was set as the evaluation scan data. In the three-dimensional analysis (Geomagic control X), the divided abutment region was selected and analyzed to verify the scan accuracy of the abutment. Statistical analysis was performed using SPSS software (${\alpha}=.05$). The accuracy of intraoral scanners was compared using the Kruskal-Wallis test and post-test was performed using the Pairwise test. The accuracy difference between the single abutment model and the bridge abutment model was analyzed by the Mann-Whitney U test. Results: The accuracy according to the intraoral scanner was significantly different (P < .05). The trueness of the single abutment model and the bridge abutment model showed a statistically significant difference and showed better trueness in the single abutment (P < .05). There was no significant difference in the precision (P = .616). Conclusion: As a result of comparing the accuracy of single and bridge abutments, the error of abutment scan increased with increasing scan area, and the accuracy of bridge abutment model was clinically acceptable in three types of intraoral scanners.

• Progress in Medical Physics
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• v.12 no.2
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• pp.185-191
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• 2001

The virtual compensator which are realized using a multileaf collimator(MLC) and three-dimensional radiation therapy Planning(3D RTP) system was designed. And the feasibility study of the virtual compensator was done to verify that it can do the function of the conventional compensator properly. As a model for the design of compensator, styrofoam phantom and mini water phantom were prepared to simulate the missing tissue area and the calculated dose distribution was produced through the 3D RTP system. The fluence maps which are basic materials for the design of virtual compensator were produced based on the dose distribution and the MLC leaf sequence file was made for the realization of the produced fluence map. Ma's algorithm were applied to design the MLC leaf sequence and all the design tools were programmed with IDL5.4. To verify the feasibility of the designed virtual compensator, the results of irradiation with or without a virtual compensator were analyzed by comparing the irradiated films inserted into the mini water phantom. The higher dose area produced due to the missing tissue was removed and intended regular dose distribution was achieved when the virtual compensator was applied.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04a
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• pp.739-741
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• 2002

좌심실의 파라미터는 심장의 기능을 분석하기 위해 측정되는 정량적인 표현으로, 특히 지역적 파라미터인 두께와 두께의 변화는 심판 기능을 분석하기에 적합한 파라미터이다. 본 연구에서는 이러한 좌심실의 지역적 파라미터를 측정하고, 이를 위해 사용되는 삼자원적 방법을 개선하여 구현함으로써 기존의 폭정 방법의 제약을 극복하고자 하였다. 또한, 측정 결과를 가시화하여 직관적인 분석이 가능하도록 하고, 이를 시스템에 구축하여 임상에서 직접적으로 활용할 수 있도록 하였다.

• Proceedings of the Korean Information Science Society Conference
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• 2001.04b
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• pp.595-597
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• 2001

본 논문에서는 가속도 센서에 의해 사고를 검지하고 사고 전후의 영상정보를 저장하는 차량용 사고분석장치를 설계하였으며 이를 위한 사고 분석 시뮬레이터를 윈도우 기반에서 OpenGL 3차원 그래픽 라이브러리를 사용하여 구현하였다. 이는 알고리즘부와 디스플레이부로 구성되며, 알고리즘부에서는 도로 영상에 대한 영상처리를 수행한다. 여기서 개선된 역우너 근법에 의해 전처리된 영상을 필터링하여 차선을 검지하고, 검지된 차선을 이용하여 차선 파라미터들을 추출하며, 디스플레이부에서 추출된 파라미터들을 입력받아서 OpenGL 라이브러리 함수를 사용하여 사고를 3차원으로 재현한다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.12
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• pp.1048-1053
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• 2015

Ablative materials in a thermal protection system for atmospheric re-entry suffers from the most severe heat fluxes and temperatures, which induces surface recession in the thickness direction. In this paper, a 0.4MW arc-heated wind tunnel is operated to test for ablative materials, and a non-contact three-dimensional surface measuring system is used to evaluate the different surface characteristics of them. In particular, by postprocessing the three-dimensional image data, the surface roughness and recession of ablative materials can be calculated before and after the wind tunnel test. Moreover, the surface properties are analyzed quantitatively by comparing volume and mass losses of the test specimens.

• Tunnel and Underground Space
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• v.31 no.1
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• pp.66-81
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• 2021

The effects of directional fracture tensor components and first invariant of fracture tensor on deformation moduli and shear moduli of fractured rock masses is analyzed based on regression analysis performed between 3-D fracture tensor parameters and deformability of DFN blocks. Using one or two deterministic joint sets, a total of 224 3-D discrete fracture network (DFN) cube blocks were generated with various configurations of deterministic density and probabilistic size distribution. The fracture tensor parameters were calculated for each generated DFN systems. Also, deformability moduli with respect to three perpendicular direction of the DFN cube blocks were estimated based on distinct element method. The larger the first invariant of fracture tensor, the smaller the values for the deformability moduli of the DFN blocks. These deformability properties present an asymptotic pattern above the certain threshold. It is found that power-law function describes the relationship between the directional deformability moduli and the corresponding fracture tensor components estimated in same direction.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05b
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• pp.665-670
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• 1998

삼차원 해륙풍 모델과 라그랑지안 입자확산모델을 이용하여 해안지역에 위치한 원전으로부터 정상운전시 장기적으로 연속 방출되는 방사성 물질의 대기확산 평가방법론을 개발하였다. 개발된 방법론을 적용하여 월성원전 부지를 대상으로 풍향, 풍속 및 운량에 따라 범주화된 각 종관기상 상태에 대해 가을철 방사성 물질 대기확산 특성을 분석하였다. 분석 결과, 방사성 물질의 계절 또는 연중 핑균적인 대기확산인자의 분포는 종관바람 둥과 같은 주풍의 발생빈도에 영향을 받을 뿐만 아니라, 해륙풍 등과 같은 국지 대기순환의 특성에 따라서도 그 분포특성이 결정됨을 알 수 있었다.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05d
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• pp.107-112
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• 1996

원전의 환경방사선 영향평가(정상시/사고시)의 정확도 및 신뢰도를 제고하기 위해서는 보다 체계적이고 과학적으로 방사성 물질의 대기중 이동을 모사·예측할 수 있는 체제가 정립되어야 한다. 해안 지역에서 빈번히 발생하는 해륙풍이 대기확산에 미치는 영향을 규명하고, 대기확산모델의 바람장 자료로 이용되는 월성원전 주변지역의 해륙풍 데이터베이스를 구축하기 위한 일환으로 삼차원 상세 해륙풍 모델을 개발하였다. 봄철 약한 북풍의 지균풍이 부는 맑은 날에 대하여 해륙풍 모델을 수행시켜 월성원전 지역의 해륙풍 특성을 분석하고 해륙풍 모델결과와 관측결과를 비교하였다.

• Journal of Dental Rehabilitation and Applied Science
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• v.31 no.4
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• pp.316-328
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• 2015

Purpose: The objects of this study was to evaluate the accuracy of the dental stone casts made from alginate impressions according to storage condition and stone pouring time. Materials and Methods: Each of upper and lower impressions of dental model was taken. The dental stone models were made immediately, 10, 30, 60, 180, 360 minutes after the impressions were taken at each storage condition. 3D models were constructed by scanning the stone model using 3D laser scanner. With Reference points, positioned on digital models, linear measurements of the dimensional change were compared by 3D metrology software, 3D average models were made and superimposition to identify the specific site of dimensional change and to measure surface deviation (mm). Results: Dental stone models which were made immediately after taking the impression showed the smallest linear dimensional change. As the stone pouring time was prolonged, the linear dimensional change was increased. More than 180 minutes after impression taking, linear dimensional change and surface distortion increased in the posterior molar region, regardless of the storage condition. Conclusion: For the optimum accuracy of the dental stone casts, alginate impression should be poured as soon as possible. If there were a need for storing, a humidor with 100% relative humidity must be used and be stored less than 180 minutes to fabricate the accurate dental model.