• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.05a
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• pp.17-18
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• 2015

In manufacturing industry, image scanning technique has made enormous progress in past decades. 3D models have been also very important to continuously monitor the related spatial information for freeform buildings. The process of shape making of 3D scanning is as follows: mesh surface segmentation, NURBS surface generation, and parametric solid model generation. We will review the process and applying process. Especially in the construction industry, 3D data collection by laser scanning has become an high quality 3D models. Therefore, in this research, we have an effort to review construction of reverse design process for freeform envelope using 3D scanning. The technology enables many 3D shape engineering and design parameterization of reverse engineering in the construction site.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.585-586
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• 2010

• Journal of the Korean Society for Precision Engineering
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• v.23 no.12 s.189
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• pp.7-15
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• 2006

• Journal of the Korea Institute of Building Construction
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• v.18 no.1
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• pp.89-98
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• 2018

Recently, the importance of the construction technology of the free-formed buildings is becoming more significant, as the interest and demand for the free-formed buildings are increasing. However, it takes much time and cost during the construction of free-formed buildings because the current construction technique of freeform concrete segments is manufactured by a formwork. Therefore, in this study, we suggested a new manufacturing process based on the LOM-type 3D printer for freeform concrete segments that can shorten construction time and reduce cost when constructing freeform concrete segments, and we also verified the feasibility of production process through mock-up test. The result shows that the suggested process shortened 47.8% of production time and saved 56.2% of cost compared to the existing steel formwork method. In conclusion, it is expected that the production method of freeform concrete segments using 3D printer will contribute to the improvement of productivity of freeform concrete segments construction and the activation of new construction method for free-formed building construction.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.7
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• pp.3528-3537
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• 2013

Evaluation indices of the panelizing optimization for Architectural freeform surfaces are proposed for quantitative evaluation through the case studies on panelizing optimization and evaluation index for Architectural freeform surfaces. Proposed evaluation items are adherence to original design intent, production ease, and continuity. The evaluation index for adherence to original design intent is surfaces fitness, the evaluation indices for production ease are planarity, planar panel ratio, and the evaluation indices for continuity are tangent continuity, and divergence. Algorithms are also suggested to compute the proposed evaluation indices.

• Journal of Korean Association for Spatial Structures
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• v.11 no.3
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• pp.137-145
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• 2011

Due to architectural requirement, the attention of single layered freeform spatial structure is increasing nowadays. Because the node of single layered structure should resist the bending and axial forces simultaneously, it is necessary to develop a new proper type of node in detail. In this study, a new type of node for single layered freeform spatial structure was proposed. And the structural performance for the node was analytically evaluated using the commercial FEM software(ABACUS). As a result, a node prototype was selected and the proposed node showed good structural behaviors.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.2
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• pp.40.1-40.1
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• 2015

Off-axis reflective optical systems have attractive advantages relative to their on-axis or refractive counterparts, for example, zero chromatic aberration, no obstruction, and a wide field of view. For the efficient operation of off-axis reflective system, the surface accuracy of freeform mirrors should be higher than the order of wavelengths at which the reflective optical systems operate. Especially for applications in shorter wavelength regions, such as visible and ultraviolet, higher surface accuracy of freeform mirrors is required to minimize the light scattering. In this work, we propose the error compensation algorithm (ECA) for the correction of wavefront errors on freeform mirrors. The ECA converts a form error pattern into polynomial expression by fitting a least square method. The error pattern is measured by using an ultra-high accurate 3-D profilometer (UA3P, Panasonic Corp.). The measured data are fitted by two fitting models: Sag (Delta Z) data model and form (Z) data model. To evaluate fitting accuracy of these models, we compared the fitted error patterns with the measured error pattern.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.4
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• pp.954-964
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• 2015

In this research, an overlapped illumination model was newly proposed for designing a freeform LED lens with a uniform illuminance distribution on its illuminating plane. Based on the proposed model and conventional illumination models, freeform lenses were designed and their performances and tolerances were compared. As a result of the tolerance analysis about thickness change in lens, position, size change, central direction change of light emission and characteristic change in LED source. This proposed model and divergent illumination model are similar to the performance about central direction change of light emission in LED source. but the uniformity illumination value in this proposed model is more remarkably value than it in divergent illumination model about characteristic change in LED source.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.3 no.4
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• pp.280-284
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• 2002

This paper presents computer simulations of the stacking and transferring system for the fast freeform fabrication system. The stacking and transferring system is essential for the fast freeform fabrication system and its stable motion is very important for consistent stacking of the cut slices. The stacking and transferring system can be modeled as a pneumatic system. The system consists of air compressor, the control valve, and the cylinder. The governing parameters have been changed and the simulation results are shown to predict the time response of the system. The results show some parameters should be correctly tuned to obtain stable system response.

• Journal of the Korea Convergence Society
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• v.7 no.5
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• pp.175-180
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• 2016

The demand for accurate freeform apsheric surface is increasing to satisfy the optical performance. In this paper, we develop the algorithm for opto-mechatronics convergence, that reconstruct the surface 3D profiles from the curvarure data along two orthogonal directions. A synthetic freeform surface with 8.4 m diameter was simulated for the testing. The simulation results show that the reconstruction error is 0.065 nm PV(Peak-to-valley) and 0.013 nm RMS(Root mean square) residual difference. Finally the sensitivity to noise is diagnosed for probe position error, the simulation results proving that the suggested method is robust to position error.