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안대건(Dae Keon Ahn),김호찬(Ho Chan Kim),정해도(Hae Do Jeong),이석희(Seok Hee Lee) Korean Society for Precision Engineering 2004 한국정밀공학회지 Vol.21 No.9
SL(Stereolithography) part is made by piling up thin layers which causes the stair stepping effect at the surface of SL parts. The effect brings about excessive surface roughness and cuts down the merits of using SL part. Hence, additional post-machining finishing such as traditional grinding is required. But the traditional post-machining is detrimental to part geometry and time consuming. In this study, therefore, a paraffin coating and grinding post-machining is newly proposed to improve the surface quality of SL part. The paraffin which has suitable properties for the proposed post-machining is coated all over the part surface. By grinding the only over-coated paraffin based on boundary of the SL part surface, the surface roughness can be improved without any damage on the part. Also, it is verified that SL part finished by the proposed post-machining process can be applied for rapid tooling as pattern through manufacturing silicon rubber molding and casting test.
안대건(Dae Keon Ahn),송정일(Jeong Il Song),권순만(Soon Man Kwon),이석희(Seok Hee Lee) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.10
Rapid Prototyping (RP) processed parts are mainly fabricated by layered manufacturing (LM) process. Thus, high complex physical model can be easily fabricated, compared with the previous NC technology. However, steps called as stair step effect occur on the slope-sided surface of the part due to the LM process. The effect is crucial to surface quality of the RP parts and depends on surface angle. Hence, prediction of the surface roughness distribution by the change of surface angle for a part to be processed is essentially required on the process planning stage of the RP. This paper focuses on investigating the characteristics of surface roughness distribution of the part fabricated by FDM (Fused Deposition Modeling) which is dealt with major technology with SL (stereolithography) in RP. Especially, the basis of indeterminate and atypical distribution on inclined surface angle close to horizontal plane is examined.
안대건(Dae Keon Ahn),송정일(Jeong Il Song),권순만(Soon Man Kwon),이석희(Seok Hee Lee) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
Stereolithography(SL) technology utilizes layered manufacturing(LM) process, which fabricates 3D physical models by stacking 2D layers. Hence, 3D physical model can be manufactured without geometric restrictions. However, part deformation occurs by stacking the layers in overhanging area. Support structure is used to prevent the deformation. After finishing build process, the support is removed from the part. But support removal burrs remain on the surface of the part so that the surface quality becomes poor. As a result, the required cost and time increase in the post processing stage. Therefore, minimization of support contact area (SCA) is required. In this paper, a computation methodology of the SCA is presented as a preparatory research related with SCA minimization in stereolithography. The STL file is directly used to compute the SCA of the 3D model including free formed surface. By several examples, it is demonstrated that the proposed methodology can be effective.
유리섬유복합재의 드릴가공조건에 대한 박리지수와 표면조도 특성
이옥규 ( Ok Kyu Lee ),안대건 ( Dae Keon Ahn ),최진호 ( Jin Ho Choi ),권진회 ( Jin Hwe Kweon ) 한국복합재료학회 2013 Composites research Vol.26 No.6
본 논문에서는 유리섬유복합재(glass fiber reinforced plastic composites)의 드릴가공조건변화에 따른 박리 지수와 표면조도 특성이 분석되었다. 드릴 가공된 홀의 입출구에서 이미지 픽셀을 이용하여 박리지수를 산출할 수 있는 관계식이 유도되었으며, 복합재 시편을 제작하여 진동 및 열 영향을 최소화할 수 있는 가공조건에서 드릴가공을 수행하여 보다 신뢰성 있게 표면조도값을 얻기 위하여 6점평균표면조도측정 방식이 적용되었다. 실험 결과로부터 GFRP 드릴가공에서 박리지수는 이송속도 증가에 감소하고, 절삭속도 증가에도 미세하게 감소함을 볼 수 있었다. 또한 드릴가공된 홀 내부에서 표면조도는 이송속도가 증가할수록 증가하고, 절삭속도 변화에는 영향을 받지 않음이 파악되었다. Characteristics of delamination factor and surface roughness by drilling condition for glass fiber reinforced plastic (GFRP) composites were investigated in this paper. An expression to quantify the delamination factor was induced by using image pixels of the entry and the experimental drilling was accomplished by fabricating several GFRP specimens in condition of minimizing the effect of vibration and heat. A method for measuring 6 points average surface roughness was applied to acquire the more reliable roughness values. The experimental results showed that the delamination factor was decreased as the feed rate was increased and it was also slightly decreased as the cutting speed was increased. Also, it was investigated that the surface roughness at inner surface of drilled holes was increased as the feed rate was increased, whereas the roughness values were not affected by the cutting speed variation.
김호찬(Ho-Chan Kim),안대건(Dae-Keon Ahn),이석희(Seok-Hee Lee) 한국자동차공학회 2003 한국자동차공학회 지부 학술대회 논문집 Vol.- No.-
Better understanding and sharing information are getting important to manage interdisciplinary product development team in a globally-distributed company. This study propose a solution to implement RPD(Rapid Product Development) system, focusing on rapid production process, for better understanding between development team members in different place and easy sharing of product information. The system developed by this research shows that SOAP(Simple Object Access Protocol) operates in distributed environment more efficiently than other RPC(Remote Procedure Call) techniques and it does not respond sensitively to firewall. And SOAP is an excellent RPC and messaging technique to exchange structured data. Procedures developed with use of SOAP are worked together with web, and users can use remote services as an application program in their computer.
자유곡면으로부터 단면정보를 이용한 황삭계획에 관한 연구
안대건,최홍태,이석희 한국경영과학회 1994 한국경영과학회 학술대회논문집 Vol.- No.1
This study deals with roughing planning by cross sectional information generated from sculptured surfaces. Bicubic Bezier surface is adopted as sculptured surfaces in this paper. The system consists of 3 parts : (1) modeling sculptured surface, (2) reconstruction of cross-section in 2D coordinates, (3) determination of roughing tool path with structural data. The system is developed by using IBM-PC in the environment of Auto CAD R11, AutoLISP and MetaWare High C. The proposed system shows an efficient algorithm for roughing planning with cross sectional informaiton.