• International Journal of Aeronautical and Space Sciences
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• v.6 no.2
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• pp.33-45
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• 2005

The 1/9-scale model of a fighter-type configuration was tested in the Micro-Craft 8ft ${\times}$ 12ft wind tunnel facility. An abrupt lift dump was found at a certain range of angle of attack under the pre-scheduled approach configuration. To avoid a probable unsatisfactory flight behavior due to the lift dump, various aerodynamic devices were suggested. Extensive tests applying the cutoff leading edge flaps, boundary layer fences, saw tooth and vortex generators were performed with flow visualization as well as force and moment measurements. Test results showed that the origin of the lift dump was caused by the secondary boundary layer flow separation generated from the strong interaction between wing and flap. Various solutions for avoiding the unfavorable feature were suggested with the merits and demerits.

• Korean Journal of Computational Design and Engineering
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• v.12 no.3
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• pp.171-181
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• 2007

Ubiquitous computing is a vision of our future computing lifestyle in which computer systems seamlessly integrate into our everyday lives, providing services and information in anywhere and anytime fashion. Augmented reality (AR) can naturally complement ubiquitous computing by providing an intuitive and collaborative visualization and simulation interface to a three-dimensional information space embedded within physical reality. This paper presents a service framework and its applications for providing context-aware u-car maintenance services using augmented reality, which can support a rich set of ubiquitous services and collaboration. It realizes bi-augmentation between physical and virtual spaces using augmented reality. It also offers a context processing module to acquire, interpret and disseminate context information. In particular, the context processing module considers user's preferences and security profile for providing private and customer-oriented services. The prototype system has been implemented to support 3D animation, TTS (Text-to-Speech), augmented manual, annotation, and pre- and post-augmentation services in ubiquitous car service environments.

• Korean Journal of Computational Design and Engineering
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• v.14 no.4
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• pp.271-280
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• 2009

An experience based training system concerning various fire situations which may result many casualties has been required to make rapid decision and improve the responsiveness. Recently, the necessity of virtual reality (VR) based training system which can replace a dangerous full-scale fire training and be easily adopted to the training or evaluation process is increasing. This study constructed tile virtual environment according to pre-defined scenarios, utilized the FDS(Fire Dynamics Simulator), three dimensional computational fire analysis program, to derive numerically simulated data on the propagation of fire. Finally, by visualizing the realistic fire and smoke behavior through virtual reality technique and implementing real-time interaction, we developed a VR-based fire training simulator. Also, in order to ensure the sense for tile real of a virtual world and reaI-time performance at the same time, we proposed appropriate data processing and space search algorithms, demonstrate d the value of proposed method through experiments.

• 한국가시화정보학회:학술대회논문집
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• 2002.11a
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• pp.49-50
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• 2002

In micro-channels, the electro-viscous effect is caused by the electrical double layer on pressure-driven liquid flow. Velocity fields of flow inside micro-channels were measured using micro-PIV system for investigating the electro-viscous effect. De-ionized water and aqueous NaCl solutions with four different concentrations were used as working fluid in a PDMS micro-channel of $100{\mu}m$ width and $66{\mu}m$ height. The pressure gradient, dP/dx, was determined from the pre-determined input flow rate Q of syringe pump. The mean velocity $u_m$ used for calculating Reynolds number was obtained from the PIV velocity field data. These are used to plot the pressure gradient as a function of Reynolds numbers. The pressure gradient far lower concentration solution $(10^{-5}\;M)$ was higher than that for the higher concentration solution. The increase of flow resistance was about $30\%\;and\;37.5\%$ at Re=0.02 and 0.06, respectively.

• Proceedings of the Korea Society for Simulation Conference
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• 2003.11a
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• pp.201-206
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• 2003

In clinical practice, CT Angiography is a powerful technique for the visualziation of blood flow in arterial vessels throughout the body. However CT Angiography images of blood vessels anywhere in the body may be fuzzy if the patient moves during the exam. In this paper, we propose a novel technique for removing global motion artifacts in the 3D space. The proposed methods are based on the two key ideas as follows. First, the method involves the extraction of a set of feature points by using a 3D edge detection technique based on image gradient of the mask volume where enhanced vessels cannot be expected to appear, Second, the corresponding set of feature points in the contrast volume are determined by correlation-based registration. The proposed method has been successfully applied to pre- and post-contrast CTA brain dataset. Since the registration for motion correction estimates correlation between feature points extracted from skull area in mask and contrast volume, it offers an accelerated technique to accurately visualize blood vessels of the brain.

• Electronics and Telecommunications Trends
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• v.34 no.1
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• pp.98-110
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• 2019

Machine learning has been applied to medical imaging and has shown an excellent recognition rate. Recently, there has been much interest in preventive medicine. If data are accessible, machine learning packages can be used easily in digital healthcare fields. However, it is necessary to prepare the data in advance, and model evaluation and tuning are required to construct a reliable model. On average, these processes take more than 80% of the total effort required. In this study, we describe the basic concepts of machine learning, pre-processing and visualization of datasets, feature engineering for reliable models, model evaluation and tuning, and the latest trends in popular machine learning frameworks. Finally, we survey a explainable machine learning analysis tool and will discuss the future direction of machine learning.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.579-586
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• 2009

4D simulation integrates the 3 dimensional model of a building with the construction schedule, and it leads to the possibility of virtually checking the construction process and the building itself in advance. However, the existing problem of 4D simulation is the difference between the demands of architects, engineers, and construction site workers in 4D simulation. This study suggests the possible way to enhance the availability of 4D simulation, considering more the practical demands from the construction site. In order to conduct this study, we build a 3D BIM model of a business-residential complex and link the model with the pre-defined construction schedule in order to make a 4D simulation. This study concludes with the optimized 4D simulation methodology based on BIM model considering the demands in perspective of the construction site. It would contribute to the harmonic collaboration among architects, engineers, and labors in the construction site when using 4D simulation based on BIM model.

• Journal of KIBIM
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• v.13 no.1
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• pp.13-21
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• 2023

The purpose of this study is to establish a system that manages the safety of buildings efficiently by finding the correlation of elements related to the safety of buildings and intuitively visualizing them. Data were collected using the data of small-scale buildings managed by public institutions and the government, and an effective analysis visualization environment was established through pre-processing. We selected safety-vulnerable factors such as the structure of the building and completion date to find the relationship, and established a model to prioritize management to find vulnerable buildings.

• School Mathematics
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• v.15 no.4
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• pp.785-799
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• 2013

The researchers developed the teaching-learning materials for 9th grade mathematically gifted students in terms of the hypothesis that the students would have opportunity for problem solving and develop various mathematical thinking through the mathematical modeling lessons. The researchers analyzed what mathematical thinking abilities were shown on each stage of modeling process through the application of the materials. Organization of information ability appears in the real-world exploratory stage. Intuition insight ability, spatialization/visualization ability, mathematical reasoning ability and reflective thinking ability appears in the pre-mathematical model development stage. Mathematical abstraction ability, spatialization/visualization ability, mathematical reasoning ability and reflective thinking ability appears in the mathematical model development stage. Generalization and application ability and reflective thinking ability appears in the model application stage. The developed modeling assignments have provided the opportunities for mathematically-gifted students' mathematical thinking ability to develop and expand.

• Proceedings of the Korea Contents Association Conference
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• 2009.05a
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• pp.283-288
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• 2009

Semantic service can be defined as the service providing search API or reasoning API based on ontology and Web Services. It performs a pre-defined task by exploiting URI, classes, and properties. This study introduces a semantic service composition method based on a semantic broker referring ontology and management information of semantic services stored in a semantic service manager with requirements of the user. The requirements consist of input instances, an output class, a visualization type, semantic service names, and property names. This composition method provides dynamically generated semantic service pipelines including composit semantic services. The user can execute the pipelines provided by the semantic broker to find a meaningful semantic pipeline. After all, this study contributes to develop a system supporting human service planners who want to find composit semantic services among distributed semantic services.