간헐폭기 BNR공정의 시뮬레이션 및 검증

유동진 ( Dong Jin Yoo ),장덕 ( Duk Chang ),남경식 ( Kyoung Sik Nam ),신형수 ( Hyung Soo Shin ) 한국물환경학회 ( 구 한국수질보전학회 ) 2005 공동 추계학술발표회 Vol.2005 No.-

음함수 곡면기법과 영역 분할법을 이용한 대형 폴리곤 모델의 홀 메움에 관한 연구

유동진(Dong-Jin Yoo) Korean Society for Precision Engineering 2006 한국정밀공학회지 Vol.23 No.1

In order to fill the holes with complex shapes in the large polygon model, a new approach which is based on the implicit surface interpolation method combined with domain decomposition method is presented. In the present study, a surface is constructed by creating smooth implicit surface from the incomplete polygon model through which the surface should pass. In the method an implicit surface is defined by a radial basis function, a continuous scalar-valued function over the domain R³. The generated surface is the set of all points at which this scalar function takes on the value zero and is created by placing zero-valued constraints at the vertices of the polygon model. In this paper the well-known domain decomposition method is used in order to treat the large polygon model. The global domain of interest is divided into smaller domains where the problem can be solved locally. LU decomposition method is used to solve a set of small local problems and their local solutions are combined together using the weighting coefficients to obtain a global solution. In order to show the validity of the present study, various hole fillings are carried out for the large and complex polygon model of arbitrary topology.

적응적 영역분할법을 이용한 임의의 점군으로부터의 형상 재구성

유동진(Dong-Jin Yoo) Korean Society for Precision Engineering 2006 한국정밀공학회지 Vol.23 No.8

In this paper a new shape reconstruction method that allows us to construct surface models from very large sets of points is presented. In this method the global domain of interest is divided into smaller domains where the problem can be solved locally. These local solutions of subdivided domains are blended together according to weighting coefficients to obtain a global solution using partition of unity function. The suggested approach gives us considerable flexibility in the choice of local shape functions which depend on the local shape complexity and desired accuracy. At each domain, a quadratic polynomial function is created that fits the points in the domain. If the approximation is not accurate enough, other higher order functions including cubic polynomial function and RBF(Radial Basis Function) are used. This adaptive selection of local shape functions offers robust and efficient solution to a great variety of shape reconstruction problems.

거리장을 이용한 삼각망의 옵셋팅

유동진(Dong-Jin Yoo) Korean Society for Precision Engineering 2007 한국정밀공학회지 Vol.24 No.9

A new method which uses distance fields scheme and marching cube algorithm is proposed in order to get an accurate offset model of arbitrary shapes composed of triangular net. In the method, the space bounding the triangular net is divided into smaller cells. For the efficient calculation of distance fields, valid cells which will generate a portion of offset model are selected previously by the suggested detection algorithm. These valid cells are divided again into much smaller voxels which assure required accuracy. At each voxel distance fields are created by calculating the minimum distances between corner points of voxels and triangular net. After generating the whole distance fields, the offset surface were constructed by using the conventional marching cube algorithm together with mesh smoothing scheme. The effectiveness and validity of this new offset method was demonstrated by performing numerical experiments for the various types of triangular net.

임의의 점 군 데이터로부터 쾌속조형을 위한 입력데이터의 자동생성

유동진(Dong-Jin Yoo) Korean Society for Precision Engineering 2007 한국정밀공학회지 Vol.24 No.11

In order to generate the input data for rapid prototyping, a new approach which is based on the implicit surface interpolation method is presented. In the method a surface is reconstructed by creating smooth implicit surface from unorganized cloud of points through which the surface should pass. In the method an implicit surface is defined by the adaptive local shape functions including quadratic polynomial function, cubic polynomial function and RBF(Radial Basis Function). By the reconstruction of a surface, various types of error in raw STL file including degenerated triangles, undesirable holes with complex shapes and overlaps between triangles can be eliminated automatically. In order to get the slicing data for rapid prototyping an efficient intersection algorithm between implicit surface and plane is developed. For the direct usage for rapid prototyping, a robust transformation algorithm for the generation of complete STL data of solid type is also suggested.

삼각망의 형상 변형

유동진(Dong-Jin Yoo) Korean Society for Precision Engineering 2007 한국정밀공학회지 Vol.24 No.11

A new approach based on mean value coordinate combined with Laplacian coordinate is proposed for shape deformation of a large polygon model composed of triangular net. In the method, the spherical mean value coordinates for closed control meshes is introduced to describe a vertex in the triangle meshes to be deformed. Furthermore, the well known quardratic least square method for the Laplacian coordinates is employed in order to deform the control meshes. Because the mean value coordinates are continuous and smooth on the interior of control meshes, deforming operation of control meshes change the shape of polygon model while preserving the intrinsic surface detail. The effectiveness and validity of this novel approach was demonstrated by using it to deform large and complex polygon models with arbitrary topologies.

자기조립단분자막을 위한 보편적이고 기능화된 긴 사슬 알킬티올 연결자의 제조

유동진 ( Dong Jin Yoo ),이경섭 ( Kyong Sub Lee ),김애란 ( Ae Rhan Kim ),남기석 ( Kee Suk Nahm ) 한국화학공학회 2011 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.49 No.3

In this research, the preparation processes for making a series of ω-mercapto alkylamine 1 and ω-mercapto alkanoic acid 2 useful for studying of the self-assembled monolayer(SAM) are described. The preparation methods of the first goal materials, ω-mercapto alkylamines 1 were carried out as follows: First, ω-phthalimide alkanol 3 was synthesized from commercially available potassium phthalimide derivatives and ω-bromoalkanol in DMF at 80℃ via substitution reaction. After refluxing ω-phthalimide alkanol 3 with hydrazine hydrate in ethanol followed by treating with c-HCl, ω-aminoalkanol 4 was obtained in 76~98% yield, accompanied with side-product 5. Bromination of hydroxyl moiety of ω-aminoalkanol 4 using aqueous hydrobromic acid furnished ω-bromoamine 6 in 34~97% yields. Substitution reaction 6 with thiourea in 95% ethanol gave ω-aminoalkanthiuronium 7, which was treated with aqueous strong base and aqueous strong sulfuric acid gave desired products, ω-mercapto alkylamines 1 through overall 5 steps. The second target material, ω-mercapto alkanoic acid 2 was prepared via 2 steps. ω-bromo alkanoic acid was reacted with thiourea to give ω-thiourea alkanoic acid 7 in 69-85%, which was treated with aqueous strong base and strong acid to furnish ω-mercapto alkanoic acid 2 in 50~98%. The fabricated long-chain alkylthiol(LCAT) can be used as linkers to immobilize protein, enzyme and various kinds of biomolecules on the surface of metallic materials(Au, Pt, Ti) by SAM, and can be useful chemical tools for the application study on the surface modification of metallic materials.

삼각망의 3차원 형상 모핑

유동진(Dong-Jin Yoo) Korean Society for Precision Engineering 2008 한국정밀공학회지 Vol.25 No.1

Shape morphing is the process of transforming a source shape, through intermediate shapes, into a target shape. Two main problems to be considered in three dimensional shape morphing are vertex correspondence and path interpolation. In this paper, an approach which uses the linear interpolation of the Laplacian coordinates of the source and target meshes is introduced for the determination of more plausible path when two topologically identical shapes are morphed. When two shapes to be morphed are different in shape and topology, a new method which combines shape deformation theory based on Laplacian coordinate and mean value coordinate with distance field theory is proposed for the efficient treatment of vertex correspondence and path interpolation problems. The validity and effectiveness of the suggested method was demonstrated by using it to morph large and complex polygon models including male and female whole body models.

셀 분할을 이용한 거리장의 효율적 계산

유동진(Dong-Jin Yoo) Korean Society for Precision Engineering 2008 한국정밀공학회지 Vol.25 No.3

A new approach based on cone prism intersection method combined with sorting algorithm is proposed for the fast and robust signed distance field computation. In the method, the space bounding the geometric model composed of triangular net is divided into multiple smaller cells. For the efficient calculation of distance fields, valid points among the triangular net which will generate minimum distances with current cell are selected by checking the intersection between current cell and cone prism generated at each point. The method is simple to implement and able to achieve an order of magnitude improvement in the computation time as compared to earlier approaches. Further the method is robust in handling the traditional sign problems. The validity of the suggested method was demonstrated by providing numerous examples including Boolean operation, shape deformation and morphing of complex geometric models.

이중원호근사법을 이용한 자유형상곡선의 오프셋 계산에 관한 연구

유동진(Dong-Jin Yoo) Korean Society for Precision Engineering 2005 한국정밀공학회지 Vol.22 No.8

In this study a general method for computing offsets of free form curves is presented. In the method arbitrary free form curve is approximated with point series considering required tolerance. The point series are offset precisely using the normal vectors computed at each point and loop removal is carried out by the newly suggested algorithm. The resulting offset points are transformed to lines and arcs using the biarc approximation method. Tangent vectors for approximation of discrete points data are calculated by traditional local interpolation scheme. In order to show the validity and generality of the proposed method , various offsettings are carried our for the base curves with complex shapes.