Earticle

본 연구의 목적은 증강현실 기술을 기반으로 상악 우측 중절치의 치아 형태 조각의 반복 실습이 가능한 콘텐츠를 개발하는 것이다. 치아 형태의 단계별 실습을 위해, 1단계부터 16단계까지의 단계별 실습스토리 보드에 의한 근심, 원 심, 협면, 설면의 특징을 반영한 단계별 치아 조각 형태를 삼차원 모델링 하였다. 이 자료가 학습자의 모바일 기기 화면 상에 출력될 수 있도록 단계별 이미지 마커를 인식하여, 증강현실 어플리케이션으로 사용할 수 있도록 제작하였다. 이를 통해 학습자는 치아 형태 조각 연습을 반복적으로 수행해 완성도 높은 상악 우측 중절치를 조각할 수 있었다. 이 콘텐츠 를 이용하여 치아 형태학 강의실 수업과 치의학 입문자의 실습이 함께 연계되어 치아 형태 조각 능력 향상에 기여하고자 한다.

This purpose of this study is to develop content that enables repetitive carving practice of the maxillary right central incisor (MRCI) based on augmented reality (AR). For a step-by-step practice of achieving the tooth shape, after creation of the storyboard from the square box shape in step 1 to the completed MRCI block in step 16, three-dimensional (3D) modeling data reflecting the characteristics of the mesial, distal, lingual, and labial surface of the MRCI were generated. An application was built in which 3D modeling data were output on the screen of the learner’s mobile device, and image markers suitable for 3D modeling in steps 1 to 16 of the MRCI model were respectively generated. Using this information, the learner could carve a high-quality MRCI by repeatedly performing the tooth shape carving exercises. With AR, we intend to contribute to improved tooth morphology carving skills by linking the theory and practical techniques for a beginners in dentistry.

Objective To evaluate the relationship between femoral muscle volume (FMV) and physiological outcomes after trans-femoral amputations (TFAs) affecting overall locomotor function in patients.Methods Seven individuals who underwent TFA and had been using a prosthesis participated in this cross-sectional study. Gait and balance were assessed using clinical tests, such as 10-m walk test, 6-minute walk test, Berg Balance Scale, and automatic balance system. Respiratory gas analysis was performed to check oxygen consumption rate. Five participants were evaluated for bilateral FMV by MR imaging and FMV was reconstructed using three-dimentional remodeling.Results In five participants, significant differences were found between the non-involved and involved sides in femur length, total FMV, and functional muscle volume (all p<0.01) in all groups except for the hip adductor volume. The %mean difference between the non-involved and involved sides was 30% for femur length, 52.55% for hip flexor volume, 26.55% for hip adductor volume, 51.86% for hip extensor volume, and 60.21% for knee extensor volume. The hip flexor volume to hip extensor volume ratio in the involved limb and oxygen consumption rate during comfortable gait were negatively correlated (r=-0.96, p=0.04).Conclusion In individuals who underwent unilateral TFA, hip girdle muscle imbalance in the involved limbs may be associated with oxygen consumption rate while using a prosthesis.

This research presents a three-dimensional modeling technique for a flexible sheet. A relative coordinate formulation is used to represent the kinematics of the sheet. The three-dimensional flexible sheet is modeled by multi-rigid bodies interconnected by out-of-plane joints and plate force elements. A parent node is designated as a master body and is connected to the ground by a floating joint to cover the rigid motion of the flexible sheet in space. Since the in-plane deformation of a sheet such as a paper and a film is relatively small, compared to out-of-plane deformation, only the out-of-plane deformation is accounted for in this research. The recursive formulation has been adopted to solve the equations of motion efficiently. An example is presented to show the validity of the proposed method.

To extend the application of digital technology to the replication of artifacts, meticulous details of the process and the diversity of three-dimensional (3D) printing output materials need to be supplemented. Thus, in this study, a bronze mirror with Hwangbichangcheon inscription was digitalized by 3D scanning, converted into a voxel model, and virtual conservation treatment was performed using a haptic device. Furthermore, the digital mold of the bronze mirror completed by Boolean modeling was printed using a 3D sand-printer. Such contactless replication based on digital technology reflects the stability, precision, expressivity, collectivity, durability, and economic feasibility of artifacts. Its application can be further extended to cultural products as well as such areas as education, exhibition, and research. It is expected to be in high demand for metal artifacts that require casting. If empirical studies through experimental research on casting are supplemented in the future, it could extend the application of digital technology-based contactless replication methods.

This study examined the applicability of digital technologies based on three-dimensional(3D) scanning, modeling, and printing to the restoration of damaged artifacts. First, 3D close-range scanning was utilized to make a high-resolution polygon mesh model of a roof-end tile with a missing part, and a 3D virtual restoration of the missing part was conducted using a haptic interface. Furthermore, the virtual restoration model was printed out with a 3D printer using the material extrusion method and a PLA filament. Then, the additive structure of the printed output with a scanning electron microscope was observed and its shape accuracy was analyzed through 3D deviation analysis. It was discovered that the 3D printing output of the missing part has high dimensional accuracy and layer thickness, thus fitting extremely well with the fracture surface of the original roof-end tile. The convergence of digital virtual restoration based on 3D scanning and 3D printing technology has helped in minimizing contact with the artifact and broadening the choice of restoration materials significantly. In the future, if the efficiency of the virtual restoration modeling process is improved and the material stability of the printed output for the purpose of restoration is sufficiently verified, the usability of 3D digital technologies in cultural heritage restoration will increase.

The Bigyeokjincheolloe (bomb shell), a scientific cultural heritage, has outstanding historical value for sustaining a gunpowder weapon of Joseon. In this study, the bomb shell was modeled through three-dimensional (3D) scanning centered on the external shape and γ-ray radiography-based on the internal shape. In particular, to improve the contrast in the radiographic image, optimization and image processing were performed. After these processes, the thickness of the inner wall (2.5 cm on average) and the positions of the three mold chaplets were clearly revealed. For exhibition purposes, the 3D model of the bomb shell was output to a 3D printer and the output was rendered realistic by coloring. In addition, the internal functional elements, such as Mokgok, fuse, mud, gunpowder, and caltrops, were reproduced through handwork. The results will contribute to the study of digital heritages in two ways. First, the internal and external shapes of the bomb shell were modeled by fusing two different technologies, namely, 3D scanning and γ-ray radiography. Second, the internal shape of the bomb shell was constructed from the original form data and the reproduction was utilized for museum exhibitions. The developed modeling approach will greatly expand the scope of museum exhibitions, from those centered on historical content to those centered on scientific content.

쌍극자 안테나는 방향성을 가지고 있으므로 지하에 매설된 선형 대상체의 주향에 따라 다른 반응을 보일 수 있다. 이런 분극 특성이 지표 레이다(GPR) 탐사 자료에 미치는 영향을 연구하려면 국내에서 주로 사용되는 전선형 쌍극자 안테나를 모델링 알고리듬에 모사해야 한다. 이를 위하여 시간영역 유한차분법에 저항 부하 방식의 송수신 안테나를 모사하는 3차원 모델링 알고리듬을 사용하였다. GPR 탐사시 수신 안테나에서 전위를 측정하는 과정을 모사하기 위하여 송신 안테나와 같은 형태로 수신 안테나를 만들었으며 상반성의 원리를 이용하여 송수신 안테나 모사방법의 타당성을 검토하였다. 안테나 방향과 탐사 대상체의 주향이 이루는 각도의 상대적인 변화와 전기적인 물성이 다른 대상체들의 회절반응을 비교하기 위하여 안테나 배열을 달리하여 수치계산을 수행하였다. 이를 위하여 반무한 공간 내에 전도체로서 쇠 파이프, 부도체로서 공동이 존재하는 지하구조를 설정하고, 다양한 안테나 방향에 대하여 3차원 모델링을 수행하여 그 결과를 비교, 고찰하였다. 쇠 파이프가 지하에 있을 때 안테나와 대상체의 주향이 평행한 경우에는 대상체에 의한 반사파만 존재하나, 서로 직교하는 경우에는 반사파 뒤에 wiggle이 수반되는 것을 볼 수 있었다. 지하에 쇠파이프와 공동이 같이 존재하는 경우, 두 대상체의 주향과 측선이 직교할 때의 반사파와 두 대상체의 주향과 측선이 45o를 이룰 때 반사파를 비교하면, 공동에 의한 반사파는 두 경우 모두 비슷하나, 쇠파이프는 주향이 안테나 방향과 평행하지 않는 경우에는 반사파의 크기가 줄어들었다. 그 결과, 안테나의 방향이 변화함에 따른 반사파의 에너지는 전도체의 경우가 부도체의 경우보다 훨씬 심하게 변화함을 확인하였다. 또한 다중 배열을 사용하는 경우, 한 측선에 관한 탐사 결과만으로도 측선과 대상체의 주향이 이루는 각도에 대한 정보의 획득이 가능함을 확인하였다.

Since dipole antenna has directivity, GPR responses are dependent on the angle of direction of the antenna relative to the orientation of subsurface targets. Thin-wire dipole antennae mostly used in our country should be simulated in the modeling algorithm in order to investigate the antenna polarization characteristics. In this study, we have used the three-dimensional finite difference time-domain modeling algorithm with resistively-loaded transmitting and receiving antennae. To simulate the way that output voltages are recorded in GPR survey, the receiving antenna was modeled in the same manner as the transmitting antenna. We have investigated the validity of the simulation with the help of the reciprocity theorem. This paper discusses that the effects of the angle between the antenna and the strike of an object and the variation of the electrical properties of the targets on the GPR responses with three antenna configurations. The algorithm has been applied to a homogeneous half-space model containing a steel pipe as conductor and/or a void as insulator for multi-configuration of antennae. For the case of the buried steel pipe, single reflection event is visible when the direction of transmitting and receiving antennae are parallel to the strike of the pipe, while the reflection accompanies wiggle when the direction of two antennae are orthogonal to the strike of the pipe. When there exist both the steel pipe and the void, the reflection from the void are not sensitive to the orientation of the antenna while that from the steel pipe becomes weaker for the antenna configuration which is not parallel to the pipe. We, therefore, have concluded that the reflection energy from a conductor is much more sensitive to the orientation of antenna than from an insulator. This research confirms that the multi-configuration survey along single profile line provides the azimuthal information of the object.

시간영역에서 변위만을 이용하여 수행되는 3차원 변위근사 유한차분 탄성파 모델링에서 자유면 경계조건을 정확히 묘사하기 위한 방법으로 육면체 내부에 매질의 물성을 정의할 것을 제안한다. 매질의 물성과 변위를 모두 격자점에 정의하는 기존의 방법과는 달리, 매질의 물성을 육면체 내부에 정의할 경우 추가적인 자유면 경계조건을 사용하지 않고도 매질의 물성의 변화만으로 자유면에서 응력이 사라진다는 자유면 경계조건을 만족시킬 수 있다. 무한 균질 매질과 반무한 균질 매질에 대하여 수치적인 해와 해석적인 해를 비교함으로써 육면체 내부에 매질의 물성을 정의하는 3차원 유한차분 탄성파 모델링법의 정확성을 확인하였다. 송신원과 수진기의 위치가 서로 바뀐 경우에 대하여 수치적으로 구한 해들을 비교함으로써 육면체 내부에 매질의 물성을 정의하는 3차원 유한차분 탄성파 모델링 알고리듬이 상반원리 (reciprocity theorem)를 만족시킨다는 것을 알 수 있었다. 또한, 수평층 구조 및 단층구조에 대하여 합성탄성파 단면도 및 스냅단면도를 성공적으로 작성할 수 있었다.

We describe a 3-D time-domain, displacement-based, finite-difference elastic wave modeling algorithm that is constructed by defining the material properties within cubes. In the conventional displacement-based finite-difference method, both displacements and material properties are defined at the nodal points, whereas in our finite-difference algorithm, displacements are still assigned to the nodal points but material properties are defined within cubes. In this case, free-surface boundary conditions, which describe stress-free at the free surface, are naturally satisfied by the changes of material properties. Through numerical examples for infinite homogeneous and semi-infinite homogeneous models, we could examine the accuracy of the 3-D finite-difference elastic wave modeling algorithm. Some numerical examples showed that the 3-D finite-differenc elastic wave modeling algorithm satisfies the reciprocity theorem and successfully generates synthetic seismograms and snapshots.

An optical measurement method of three dimensional surface profiles which is named the slit beam projection is suggested and practically implemented. This method is intended especially for noncontact and fast digitization of sculptured surfaces for CAD modeling and die manufacturing. Its basic principles are based on geometric optics. Deatiled optical principles and an sub-pixel image processing technique to enhance the measuring resolutions are described in this study. The measuring performances of the slit beam projection are presented and discussed to demonstrate that an actual measuring accuracy of below .+-. 0.2mm can be achived over the whole measuring range(500mm*300mm*200mm)

안테나에서 방사되는 전자기파의 반사 에너지는 지하 매질과 대상체 사이의 물성 차이에 따 른 경계조건 뿐만 아니라, 안테나의 방향과 대상체의 주향과의 관계에 따라 달라진다. 이와 같은 물성 차이 와 방향성에 따른 GPR 반응을 쌍극자 안테나를 고려한 3차원 시간영역 유한차분 알고리듬을 사용하여 수 치 계산하였다. 사용된 선형 쌍극자 안테나의 길이는 0.74m로, 공기 중에서 주주파수는 200MHz이다. 전 기적인 물성이 다른 대상체들에 의한 회절반응을 비교하기 위하여 반무한 매질에 쇠파이프 또는 공동이 존 재하는 지하구조를 설정하였으며, 대상체의 형태에 따른 비교를 위하여 사각기둥과 원통형 대상체를 사용하 였다. 안테나의 방향과 대상체의 주향이 같은 경우와 직교하는 두 경우에 대해 입사파와 대상체에 의해 회 절된 파들을 각각 세 평면에 대한 스냅샷으로 가시화하여 비교 분석하였다. 공동의 경우 대상체의 형태와 안 테나의 방향 변화가 반사파에 영향을 거의 주지 않았다. 이에 반해 쇠파이프에 의한 반사파는 대상체의 형 태, 주향과 안테나의 방향과의 관계에 따라 양상이 크게 달라졌다. 즉, 안테나와 쇠파이프의 주향이 직교하 는 경우 원통형 매설체에는 반사파에 wiggle이 생겼다.

Reflection energies of electromagnetic waves radiating from a dipole antenna vary with not only boundary conditions between subsurface and an object but also antenna orientation relative to the strike of the target. To investigate GPR responses depending on the target property and geometry, we have conducted numerical simulation using the three-dimensional finite difference time-domain modeling algorithm considering a thin-wire dipole antenna. We used an antenna with 0.74m in length, and its main frequency in the air is 200MHz. We made a homogeneous half-space model containing a steel pipe or a void plastic pipe to compare the differences to the electromagnetic properties. We chose a cylinder or a box as the shapes of the objects, and two transmitting antenna orientations. We have visualized the main electric field distributions as a snapshot when the direction of the transmitting antenna was both parallel and perpendicular to the strike of the target. The reflection from the void pipe was not sensitive to either the orientation of the antenna or the shape of the pipe. For the case of buried steel pipe, however, reflection energy was sensitive to both its shape and the antenna direction relative to its strike. The reflection accompanied wiggles when the antenna orientation is orthogonal to the cylindrical steel pipe.

This paper summarizes the work on the development of a simulation program for modelling the process of machining quasi-three dimensional shape with the excimer laser beam on a constantly moving polymers. Relatively simple masks of rectangle, triangle and half circle shape are considered. The etching depth is calculated by considering the number of laser pulses irradiated on the specimen surface. It was found that similar shapes as experimental results can be obtained by choosing suitable parameters of moving velocity, moving distance and mask sizes.

공간과 형태 디자인에 있어서 스터디모델은 완성될 공간이나 형태가 디자인되는 공간과 형태에 구체적인 시각적 매개체를 제공하며, 보다 근본적으로 디자인도면에 대한 상호 보완적 수단으로서 이용된다. 즉 스터디모델은 2차원적인 속성을 지니는 디자인 도면에 3차원적인 이해 수단을 추가적으로 부여한다. 따라서 디자인이 진행되는 동안 구체적인 공간의 형태와 공간구성을 디지털스터디모델을 이용하여 자유로운 각도에서 시각적으로 감지하며 공간과 형태를 분석하게 해준다. 일반적으로 유형적인 재료를 사용하여 제작되는 스터디모델은 디자인 과정에서 디자인 내용의 변경과 스터디모델의 용도에 따라서 여러 번 제작되어야 하며, 디자인도면과 모델의 관계는 공간의 지각과 이해를 통해서만 이루어진다. 이것은 디자인도면과 스터디모델 매체사이의 상호보완성이 동시에 이루어지지 않기 때문이다. 그러나 본 연구에서 제안된 3차원 디지털 디자인 프로세스를 이용하면, 즉각적인 시각적 표현과 더불어 디자인 단계에서 다양한 분석과 디지털 디자인모델 결과물들을 얻어낼 수 있게 된다. 결국 디자인계획과 디자인 구체화 단계에서 디지털디자인 프로세스를 활용할 경우 입체적 표현을 실시간으로 적용할 수 있으며, 3차원 디지털모델을 시각화하여 최종 디자인을 위한 공간과 형태의 다양한 분석이 가능하게 된다.

In space design or form design step, recognized necessity of digital design practical use. Also, deduced systematized analysis method that can use various function of CAD system actively. These method can promote the practical use because third dimensional digital design escapes plan and design process in concept that get presentation result after is completed, establishes role of effective and systematic digital design at planning and design of space or form. This uses by a design tool that ease designer's judgment and space and form analysis in architectural planning and design process that third dimension digital design is not part by a simplicity design tool. Share and takes advantage of digital design process method that is deduced in this study, need continuance of connection study for more effective and systematic digital design methodology deduction. Need public ownership of teaching material development and teaching method that can deliver extended third dimension digital design process.

이 연구에서는 해운대 석각을 대상으로 3차원 레이저 스캐닝 시스템을 적용하여 디지털복원 및 표면심도 모델링을 수행하였다. 먼저 석각의 3차원 디지털복원은 광대역 및 정밀 스캐너를 이용하여 점군 데이터를 획득하였고, 정합, 병합, 필터링, 폴리곤 메쉬, 도면화 작업 순으로 진행하였다. 특히 정밀 스캐닝 폴리곤은 광대역 폴리곤에 비해 글자의 필획, 음각깊이 및 선명도 등이 매우 뛰어났다. 표면심도 모델링은 폴리곤 분리, 기준축 설정, 기준점 선정, 등고선도 맵핑 및 폴리곤 병합을 통해 완성하였으며, 사진과 폴리곤 이미지에 비해 글자의 상대적 음각깊이(5~17㎜)와 윤곽이 매우 뚜렷하게 나타났다. 광대역 및 정밀 스캐닝을 병합한 디지털복원 기술을 통해 석각의 전체 형태와 미세형상을 신속하고 정확하게 복원하였고, 표면심도 모델링은 육안과 사진으로 불분명했던 부분을 가시적으로 표현해주었다. 앞으로 정기적인 모니터링을 통해 석각의 다양한 손상과 시간에 따른 주변 환경 변화를 수치적으로 분석할 수 있을 것으로 판단된다.

This study was focused on digital restoration and surface depth modeling applying the three-dimensional laser scanning system of the Haeundae Stone Inscription. Firstly, the three-dimensional digital restoration carried out acquiring of point cloud using wide range and precision scanner, thereafter registering, merging, filtering, polygon mesh and surveyed map drawing. In particular, stroke of letters, inscribed depth and definition appearing the precision scanning polygon was outstanding compared with ones of the wide range polygon. The surface depth modeling completed through separation from polygon, establishment of datum axis, selection of datum point, contour mapping and polygon merging. Also, relative inscribed depth (5~17㎜) and outline by the depth modeling was well-defined compared with photograph and polygon image of the inscription stone. The digital restoration technology merging wide range and precision scanning restored the total and detailed shape of the Stone Inscription quickly and accurately. In addition, the surface depth modeling visibly showed unclear parts from naked eye and photograph. In the future, various deteriorations and surrounding environ-ment change of the Stone Inscription will be numerically analyze by periodic monitoring.

Surface roughness is an index which determines the quality of machined products and is influenced by the cutting parameters. In this study the average surface roughness Ra (value) for Aluminum after ball end milling operation has been measured. 84 experiments have been conducted varying cutter axis inclination angle (φ degree), spindle speed (S rpm), feed rate (fy mm/min), radial depth of cut (feed fx mm), axial depth of cut (t mm) in order to find Ra. This data has been divided into two sets on a random basis; 68 training data set and 16 testing data set. The training data set has been used to train different ANN and ANFIS models for Ra prediction. And testing data set has been used to validate the models. Better ANFIS model has been selected based on the minimum value of Root Mean Square Error (RMSE) which is constructed with three Gaussian membership functions (gaussmf) for each input variables and linear membership function for output. Similarly better ANN model has been selected based on the minimum value of Root Mean Square Error (RMSE) and Mean Absolute Percentage of Error (MAPE). The Selected ANFIS model has been compared with theoretical equation output, ANN and Response Surface Methodology (RSM). This comparison is done based on RMSE and MAPE. The comparison shows that selected ANFIS model gives better result for training and testing data. So, this ANFIS model can be used further for predicting surface roughness of Aluminum for three dimensional end milling operation.

In this paper, we introduce the 3D modeling of the coronal magnetic field in the solar active region by extrapolating from the 2D observational data numerically. First, we introduce a nonlinear force-free field (NLFFF) extrapolation code based on the MHD-like relaxation method implementing the cleaning a numerical error for Div B proposed by Dedner et al. 2002 and the multi-grid method. We are able to reconstruct the ideal force-free field, which was introduced by Low & Lou (1990), in high accuracy and achieve the faster speed in the high-resolution calculation (512^3 grids). Next we applied our NLFFF extrapolation to the solar active region NOAA 10930. First of all, we compare the 3D NLFFF with the flare ribbons of Ca II images observed by the Solar Optical Telescope (SOT) aboard on the Hinode. As a result, it was found that the location of the two foot-points of the magnetic field lines well correspond to the flare ribbon. The result indicates that the NLFFF well capture the 3D structure of magnetic field in the flaring region. We further report the stability of the magnetic field by estimating the twist value of the field line and finally suggest the flare onset mechanism.

In this study, artificial neural networks were used to determine the intensity of brightness in interior spaces. The illumination elements to illuminate indoor spaces were considered, not individually, but as a system. So, during the planned maintenance periods of an illumination system, after its design and installation, simple brightness level measurements must be taken. For a three-dimensional evaluation of the brightness level in indoor spaces in a speedy and accurate manner, the obtained brightness level measurement results and artificial neural network model were used. Upon estimation of the most suitable brightness level for indoor spaces by using the artificial neutral network model, the energy demands required by the illumination elements decreased. Consequently, in this study, with estimations of brightness levels, the extent to which the artificial neutral networks become successful was observed and more correct results have been obtained in terms of both economy and usage.

Objective : Three-dimensional (3D) printing in vascular surgery is trending and is useful for the visualisation of intracranial aneurysms for both surgeons and trainees. The 3D models give the surgeon time to practice before hand and plan the surgery accordingly. The aim of this study was to examine the effect of preoperative planning with 3D printing models of aneurysms in terms of surgical time and patient outcomes. Methods : Forty patients were prospectively enrolled in this study and divided into two groups : groups I and II. In group I, only the angiograms were studied before surgery. Solid 3D modelling was performed only for group II before the operation and was studied accordingly. All surgeries were performed by the same senior vascular neurosurgeon. Demographic data, surgical data, both preoperative and postoperative modified Rankin scale (mRS) scores, and Glasgow outcome scores (GOS) were evaluated. Results : The average time of surgery was shorter in group II, and the difference was statistically significant between the two groups (p<0.001). However, no major differences were found for the GOS, hospitalisation time, or mRS. Conclusion : This study is the first prospective study of the utility of 3D aneurysm models. We show that 3D models are useful in surgery preparation. In the near future, these models will be used widely to educate trainees and pre-plan surgical options for senior surgeons.