• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.9
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• pp.333-340
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• 2018

Recently, free-form buildings have been designed with complex shapes due to digitization of the construction industry. Exterior and interior components of free-form buildings have free cross sections and curved shapes. Therefore, structural members with curvature are frequently seen. In the modeling and stability evaluation of these structures, commercial programs using classical finite element analysis are not able to perform rapid shape modeling, resulting in a decrease in productivity. Therefore, in this study, pre- and post-processing modules were developed using a prior study to rapidly model the surface of a free-form building and to automatically generate frame structures that make up the cladding. The developed modules use a subdivision algorithm with spline curves. This algorithm is used to automatically generate analytical elements from the configuration information of NURBS curves. In addition, the deformation after analysis can be viewed more realistically. The modules can quickly construct complex curved surfaces. An analysis model of the frame structure was also automatically generated. Therefore, the modules could contribute to the productivity improvement of free-form building design.

• Korean Journal of Computational Design and Engineering
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• v.1 no.1
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• pp.65-75
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• 1996

This paper describes an automatic finite element(FE) mesh generation for three-dimensional structures consisting of free-form surfaces. This mesh generation process consists of three subprocesses: (a) definition of geometric model, i.e. analysis model, (b) generation of nodes, and (c) generation of elements. One of commercial solid modelers is employed for three-dimensional solid and shell structures. Node is generated if its distance from existing node points is similar to the node spacing function at the point. The node spacing function is well controlled by the fuzzy knowledge processing. The Delaunay method is introduced as a basic tool for element generation. Automatic generation of FE meshes for three-dimensional solid and shell structures holds great benefits for analyses. Practical performances of the present system are demonstrated through several mesh generations for three-dimensional complex geometry.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1994.04a
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• pp.272-272
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• 1994

신약개발에 있어서 대사연구는 약효의 species difference, 독성기전, 그리고 in vitro와 in vivo의 약효차이를 이해하는데 매우 중요한 역할을 담당하며 그 연구 영역을 넓혀가고 있다. 본 연구에서는 항혈전제로 개발 가능성이 있는 phosphodiesterase inhibitor인 KR30289의 rat과 rabbit에서 대사 연구를 통하여 약리효과의 상이점을 밝히고져 하였다. Mass analysis를 통하여 urinary 대사체의 구조를 규명한 결과 KR30289를 경구 투여 (1mg/kg)시 hydroxy derivative(M1)와 O-dealkylated derivative(M2)로 변환되어 urine으로 배설되었고 parent compound는 검출되지 않았다 M1과 M2 모두 free form, glucuronide conjugate, 그리고 sulfate conjugate 형태로 검출되었으나 rat과 rabbit 두 종간의 M1과 M2의 비율에서는 커다란 차이점을 보여주었다 rat의 경우 M2가 94% (free form : 14%, glucuronide conjugate 58%. sulfate conjugate, 22%)이었으며 rabbit에서는 M1이 54%로 상대적으로 많이 생성되었다(free form : 11%, glucuronide conjugate : 22%, sulfate conjugate 21%). 이와같이 두종간의 상이한 metabolic profile로 인하여 약리효과의 차이가 유발될수 있다고 추론된다.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.29A no.10
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• pp.8-16
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• 1992

Despite recent advances in electrical switch architectures, the practical switch performance is limited by both the technological and physical constraints of electrical device and wiring. Though an optical switch can have good features, optical devices are of poor quality. Therefore, we propose and study the switching architecture based on free-space optical interconnections and electrical logic devices. And an exchanging method using packets with a parallel form is introduced to solves the blocking problem of the switch that resulted from switching packets with a serial form. The free-space optical interconnections overcome the defects of electrical switch, such as, the complex connections of the wires. The proposed and demonstrated switch is nonblocking, simple and high performable. Other attractive features of the proposed switch include the guarantee of first-in first-out packet sequence. In this thesis, we also discuss the performance of proposed switch and show the experimental results of the 4$\times$4 switch.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.112-113
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• 2018

As the building becomes more sophisticated, indoors and outdoors exterior decoration of construction has been increased. However, it is very difficult to produce an FDM(Free-form Decorative Mold) that meets the requirements of quality, durability, and ease of installation, resulting in a high cost. Therefore, the objective of this study is basic research for economical production of FDM production technology while satisfying the above requirements. For this study, the authors analyze the details of the shape and requirements of the FDM, and the production details and processes that reflect the characteristics. The results of this study can utilize to develop algorithms for production and management of academically efficient FDM and can utilize to secure FDM production technology at commercial level.

• Journal of Ocean Engineering and Technology
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• v.14 no.1
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• pp.95-101
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• 2000

In general, free form design depends on B-spline which is used for the generating hull lines in most of shipyards. But, nowadays, the NURBS method is applied to free form modeling method, which is able to more flexible transformation than B-Spline, and then became industrial standard in the various field. Therefore, this method has been considerably applied in new application fields which are required free form modelling. In this paper, the program called 2DSURF with 5 modules and developed for the generation of hull lines is described. It is examined whether the program can be applied to body lines, sheer lines, and half breadth lines.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.4
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• pp.455-461
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• 2010

Automated magnetic abrasive polishing which can be applied after machining of the mold on a machine tool without unloading is very effective for finishing a complicated injection mold surface. This study aims to realize one step polishing of free form surface with the same machine tool. For this purpose, magnetic flux density according to the change of curvature radii was simulated for selecting polishing conditions and experimental verification was performed with a complicated mold of aluminum alloy. As a result, it was seen by the simulation that the magnetic flux density at a gradual curvature of the mold was higher than at a steep curvature and the higher magnetic flux density produced the better surface roughness in the experimentation. The deviation for the surface roughness of the mold decreased on the whole and the uniform mold surface was obtained after the automated magnetic abrasive polishing.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.9
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• pp.745-751
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• 2016

This paper presents the acceleration and deceleration control of free-form surfaces. A rapid variation of acceleration (or Deceleration) drives the system into a machine shock, resulting in the inaccuracy of the path control of the NURBS curve. The pattern of acceleration control can be established using the curvature of the NURBS curve. The curvature can be easily calculated from the first and second derivative of the NURBS curve used in Taylor's expansion for NURBS interpolation. However, the derivatives are not used in the recursive method for NURBS interpolation. Hence, we attempted the difference-derivatives for calculating the NURBS curvature. Both, Taylor's expansion and the recursive method, are used jointly for controlling the acceleration in the same interpolation algorithm.

• Proceedings of the Korea Multimedia Society Conference
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• 2004.05a
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• pp.271-274
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• 2004

영상정합을 통한 의료영상 분석방법들 중 동일환자에 대한 선형적 다중모달리티 정합이 널리 이용되고 있다. 그러나 실제적으로 여러 종류의 환자영상 취득이 어렵거나 해부학적 영상정보가 손실되는 경우가 적지 않다 본 논문에서는 표준 형상을 가지는 정상인 해부학적 뇌영상에 대한 환자 기능적 뇌영상의 정합방법을 제안한다. 먼저 두 영상간 모멘트 정보 매칭 및 초기선형 변환을 수행하고, 3차원 B zier 함수 기반 free-form 변형기법을 이용한 비선형 정합을 수행하여 정합 영상간 형상 차이를 최소화한다 제안방법은 환자 기능영상의 해부학적 분석 뿐 아니라 시술전-시술중 영상정합을 통한 영상유도시술에도 확장 적용될 수 있다.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.12
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• pp.99-105
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• 1996

Increasing demands on precision machining of free-form surfaces have necessitated the tool to move not only with position error as small as possible, but also with smoothly varying feedrates. In this paper, linear, circular and spline interpolators were developed in reference-pulse type using PC. M-SAM and M-DAM were designed by the comparison and analysis of previous interpolation methods. Spline interpolator was designed to follow the free-form curves. To apply to the real cutting process, constant feedrate compensation and acceleration-deceleration compensation were conceived. Finally, its performance was tested using retrofitted milling machine. As a result, new interpolation algorithm is favorable in precision machining of free-form curves.