• Korean Journal of Computational Design and Engineering
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• v.10 no.6
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• pp.444-454
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• 2005

Recently, the requirements of multi-resolution models of a solid model, which represent an object at multiple levels of feature detail, are increasing for engineering tasks such as analysis, network-based collaborative design, and virtual prototyping and manufacturing. The research on this area has focused on several topics: topological frameworks for representing multi-resolution solid models, criteria for the level of detail (LOD), and generation of valid models after rearrangement of features. As a solution to the feature rearrangement problem, the new concept of the effective zone of a feature is introduced in the former part of the paper. In this paper, we propose a feature-based non-manifold modeling system to provide multi-resolution models of a feature-based solid or non-manifold model on the basis of the effective feature zones. To facilitate the implementation, we introduce the class of the multi-resolution feature whose attributes contain all necessary information to build a multi-resolution solid model and extract LOD models from it. In addition, two methods are introduced to accelerate the extraction of LOD models from the multi-resolution modeling database: the one is using an NMT model, known as a merged set, to represent multi-resolution models, and the other is storing differences between adjacent LOD models to accelerate the transition to the other LOD. We also suggest the volume of the feature, regardless of feature type, as a criterion for the LOD. This criterion can be used in a wide range of applications, since there is no distinction between additive and subtractive features unlike the previous method.

• The korean journal of orthodontics
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• v.46 no.5
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• pp.280-289
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• 2016

Objective: The aim of this study was to analyze tooth movement and arch width changes in maxillary dentition following nonextraction treatment with orthodontic mini-implant (OMI) anchorage in Class II division 1 malocclusions. Methods: Seventeen adult patients diagnosed with Angle's Class II division 1 malocclusion were treated by nonextraction with OMIs as anchorage for distalization of whole maxillary dentition. Three-dimensional virtual maxillary models were superimposed with the best-fit method at the pretreatment and post-treatment stages. Linear, angular, and arch width variables were measured using Rapidform 2006 software, and analyzed by the paired t -test. Results: All maxillary teeth showed statistically significant movement posteriorly (p < 0.05). There were no significant changes in the vertical position of the maxillary teeth, except that the second molars were extruded (0.86 mm, p < 0.01). The maxillary first and second molars were rotated distal-in ($4.5^{\circ}$, p < 0.001; $3.0^{\circ}$, p < 0.05, respectively). The intersecond molar width increased slightly (0.1 mm, p > 0.05) and the intercanine, interfirst premolar, intersecond premolar, and interfirst molar widths increased significantly (2.2 mm, p < 0.01; 2.2 mm, p < 0.05; 1.9 mm, p < 0.01; 2.0 mm, p < 0.01; respectively). Conclusions: Nonextraction treatment with OMI anchorage for Class II division 1 malocclusions could retract the whole maxillary dentition to achieve a Class I canine and molar relationship without a change in the vertical position of the teeth; however, the second molars were significantly extruded. Simultaneously, the maxillary arch was shown to be expanded with distal-in rotation of the molars.

• Journal of Korea Game Society
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• v.16 no.4
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• pp.69-78
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• 2016

With the development of game technology, the realistic game graphics, interface technology, and various content services with immersion are being required in the content area. NUI has been developed through CLI and GUI. Unlike the conventional methods, it is an interface that could be the intuitive and realistic interface for human as a natural action realized. we propose a boxing simulation game using leap motion of it. Providing a realistic 3D experimental environment through VR headsets game, we also propose a method that can be calculated the scores if the user-controlled interface (fist) could be to punch the target (sandbag) of the internal in accordance with changes of the angle of target impact with the physical characteristics.

• Journal of the Korean Geographical Society
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• v.48 no.6
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• pp.994-1008
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• 2013

In this paper, we describe two exploratory examples in the use of Augmented Reality (AR) for geographical visualization regarding refinement of visual content in geography textbooks and learning motivation of geography students. Currently, teaching and learning materials with AR technology and their utilization in the geography classroom have become a new topic in geographical research themes, and this trend has increased. Adequate development and utilization of geographical materials is an important starting point for smart education research in geography. This paper describes the system and software, and the implication of marker AR applications for teaching and learning geography in the classroom. For the AR applications to be utilized in geography education, two marker based AR examples, virtual globe and visualization of topographical features, are presented and their utilization aspects are discussed. Finally, from the discussion stated in this paper, it can be inferred that AR is useful for exploring geographical materials, and marker based AR will contribute to progress in spatial science and geographical education research.

• Journal of information and communication convergence engineering
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• v.9 no.1
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• pp.83-88
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• 2011

Abstract. Image segmentation is always a challenging task in computer vision as well as in pattern recognition. Nowadays, this method has great importance in the field of stereo vision. The disparity information extracting from the binocular image pairs has essential relevance in the fields like Stereoscopic (3D) Imaging Systems, Virtual Reality and 3D Graphics. The term 'disparity' represents the horizontal shift between left camera image and right camera image. Till now, many methods are proposed to visualize or estimate the disparity. In this paper, we present a new technique to visualize the horizontal disparity between two stereo images based on image segmentation method. The process of comparing left camera image with right camera image is popularly known as 'Stereo-Matching'. This method is used in the field of stereo vision for many years and it has large contribution in generating depth and disparity maps. Correlation based stereo-matching are used most of the times to visualize the disparity. Although, for few stereo image pairs it is easy to estimate the horizontal disparity but in case of some other stereo images it becomes quite difficult to distinguish the disparity. Therefore, in order to visualize the horizontal disparity between any stereo image pairs in more robust way, a novel stereo-matching algorithm is proposed which is named as "Quadtree Segmentation of Pixels Disparity Estimation (QSPDE)".

• Journal of the Korea Society for Simulation
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• v.25 no.1
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• pp.35-43
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• 2016

Increasing the proportion of an embedded system in automotive industry, test methods for evaluation and fault detection of the embedded system have been researched. HILS is a test method that is used in the development and test of complex real-time embedded systems. In this study, we defined the HILS method of the ECU, one of the embedded systems used in automobiles. Our method is to create a test model that can provide a virtual vehicle environment to the ECU on the basis of the actual vehicle data. The test model has reference information that can transmit the sensor signal and CAN Message into the ECU from HILS tester. In this study, the HILS can detect faults of the target ECU.

• Journal of the Korean Solar Energy Society
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• v.31 no.6
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• pp.8-22
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• 2011

Investigations on modeling methods of a CFD wind resource prediction program, WindSim for a ccurate predictions of wind speeds were performed with the field measurements. Meteorological Masts having heights of 40m and 50m were installed at two different sites in complex terrain. The wind speeds and direction were monitored from sensors installed on the masts and recorded for one year. Modeling parameters of WindSim input variables for accurate predictions of wind speeds were investigated by performing cross predictions of wind speeds at the masts using the measured data. Four parameters that most affect the wind speed prediction in WindSim including the size of a topographical map, cell sizes in x and y direction, height distribution factors, and the roughness lengths were studied to find out more suitable input parameters for better wind speed predictions. The parameters were then applied to WindSim to predict the wind speed of another location in complex terrain in Korea for validation. The predicted annual wind speeds were compared with the averaged measured data for one year from meteorological masts installed for this study, and the errors were within 6.9%. The results of the proposed practical study are believed to be very useful to give guidelines to wind engineers for more accurate prediction results and time-saving in predicting wind speed of complex terrain that will be used to predict annual energy production of a virtual wind farm in complex terrain.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.48 no.4
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• pp.86-93
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• 2011

The ship movement implies current position, wave, wind, and its other factors. We need to know exactly the location and the shape of the ship and control its motion because of these effects. In order to control the small ship according to the movement of the large ship, the position and shape of the ship should be given first. In this paper we propose the method with which we know the current status of the ship without dynamic equations of the ship. There are several methods to track the system such as optical, radio frequency, radar, camera, and infrared light. We propose the movement of the ship using the GPS absolute axis. But, the genuine error by the GPS itself and the movement of the ship cause the result of the GPS of not being accurate. This paper reduces the error of the location and the shape of the ship and gives the exact values of the ship movements even if the GPS implies some error itself.

• The Journal of the Convergence on Culture Technology
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• v.6 no.4
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• pp.165-170
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• 2020

In this study, after applying VR 360-degree video contents for intravenous infusion education, basic data on whether VR 360-degree video can be applied as educational content in the future is prepared by grasping the empathy and flow of nursing students in graduating grades. The VR 360 degree intravenous infusion educational content was developed in four-step process of planning, production, modification and completion. The design of this study was descriptive research, and the study period was from November 9 to November 22, 2019. The subjects of this study were 4th grade nursing students at a university, totaling 64 students. Nursing students watched VR 360 degree intravenous infusion educational content using HMD(head mounted display) under the safety management of the researcher. As a result of the study, the empathy of nursing students was 5.32±0.88 points and the flow was 6.02±0.84 points out of 7-point scale. The VR 360 degree intravenous infusion educational content developed in this study can be used as an educational medium in subjects and comparative departments, and it is necessary to specifically develop and verify teaching and learning methods in future studies.

• The Journal of Advanced Prosthodontics
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• v.7 no.6
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• pp.431-436
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• 2015

PURPOSE. The aim of this study was to evaluate occlusal contacts generated by 3 different biogeneric design modes (individual (BI), copy (BC), reference (BR)) of CEREC software and to assess the designs subjectively. MATERIALS AND METHODS. Ten pairs of maxillary and mandibular casts were obtained from full dentate individuals. Gypsum cast contacts were quantified with articulating paper and digital impressions were taken. Then, all ceramic crown preparation was performed on the left first molar teeth and digital impressions of prepared teeth were made. BI, BC, and BR crowns were designed. Occlusal images of designs including occlusal contacts were superimposed on the gypsum cast images and corresponding contacts were determined. Three designs were evaluated by the students. RESULTS. The results of the study revealed that there was significant difference among the number of contacts of gypsum cast and digital models (P<.05). The comparison of the percentage of virtual contacts of three crown designs which were identical to the contacts of original gypsum cast revealed that BI and BR designs showed significantly higher percentages of identical contacts compared with BC design (P<.05). Subjective assessment revealed that students generally found BI designs and BR designs natural regarding naturalness of fissure morphology and cusp shape and cusp tip position. For general occlusal morphology, student groups generally found BI design "too strong" or "perfect", BC design "too weak", and BR design "perfect". CONCLUSION. On a prepared tooth, three different biogeneric design modes of a CAD/CAM software reveals different crown designs regarding occlusal contacts and morphology.