• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 춘계학술대회 논문집
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• pp.767-770
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• 2000

A novel process is newly developed for building RP(Rapid Prototyping) parts using a sheet lamination technique. The build process of existing sheet lamination type RP machines consists of the following steps : feeding, lamination and cutting. In this process, the laminated part of an object is often scratched by a cutter or damaged by a laser beam due to the cutting operation preceded by lamination, In addition, decubing of the unused portion from the laminated block is difficult. In the new process, cutting operation is performed before lamination. The cutting operation takes place while a paper sheet is firmly attached on the plate using electrostatic force. Then liquid glue is applied to the calculated region of the given contour for lamination. The process aims to manufacture a $2k RP machine, what we call the Freeform Mater I, that can use A4 or latter-size used papers. A prototype machine that demonstrates the design concept is built and further research issues are discussed.

• Bulletin of the Korean Chemical Society
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• 제33권2호
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• pp.613-619
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• 2012

We applied several machine learning methods for developing QSAR models for prediction of acute toxicity to fathead minnow. The multiple linear regression (MLR) and artificial neural network (ANN) method were applied to predict 96 h $LC_{50}$ (median lethal concentration) of 555 chemical compounds. Molecular descriptors based on 2D chemical structure were calculated by PreADMET program. The recursive partitioning (RP) model was used for grouping of mode of actions as reactive or narcosis, followed by MLR method of chemicals within the same mode of action. The MLR, ANN, and two RP-MLR models possessed correlation coefficients ($R^2$) as 0.553, 0.618, 0.632, and 0.605 on test set, respectively. The consensus model of ANN and two RP-MLR models was used as the best model on training set and showed good predictivity ($R^2$=0.663) on the test set.

• International Journal of CAD/CAM
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• 제3권1_2호
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• pp.85-95
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• 2003

During the design of dies and molds, the cavity of the object is obtained by subtracting it from a surrounding rectangular block. This box is subsequently split into two halves by the parting surface. Similar problems also occur in some RP processes such as LOM, SGC, SLS and 3DP where the machine produces a block inside which the prototype is buried. Determining the orientation of the object inside the box and the corresponding parting surface taking appropriate constraints into account have been addressed by several researchers. However, given the parting surface, the problem of splitting the box development of a software package called OptiLOM (now a module of an RP software Magics 8.0), the authors realized non-triviality of this problem since the loop can spread over as many as 5 faces of the box. In this paper, the authors have tried to bring out the importance of this problem and have presented their algorithm to solve it.

• International Journal of CAD/CAM
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• 제6권1호
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• pp.183-192
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• 2006

A CAD/CAM system has been developed for rapid prototyping (RP) of microfluidic devices based on excimer laser micromachining. The system comprises of two complementary softwares. One, the CAM tool, creates part programs from CAD models. The other, the Simulator Tool, uses a part program to generate the laser tool path and the 2D and 3D graphical representation of the machined microstructure. The CAM tool's algorithms use the 3D geometry of a microstructure, defined as an STL file exported from a CAD system, and process parameters (laser fluence, pulse repetition frequency, number of shots per area, wall angle), to automatically generate Numerical Control (NC) part programs for the machine controller. The performance of the system has been verified and demonstrated by machining a particle transportation device. The CAM tool simplifies part programming and replaces the tedious trial-and-error approach to creating programs. The simulator tool accepts manual or computer generated part programs, and displays the tool path and the machined structure. This enables error checking and editing of the program before machining, and development of programs for complex microstructures. Combined, the tools provide a user-friendly CAD/CAM system environment for rapid prototyping of microfluidic devices.

• 동력기계공학회지
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• 제12권2호
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• pp.29-34
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• 2008

Bellows is widely used in many industrial fields as it provides a relatively simple means of absorbing mechanical shock, vibration and thermal deformation with flexibility. In this study, the inherent dynamic characteristics of curved bellows are numerically studied according to the variation of angle, curvature and crest density, etc. For these numerical studies, a parametric finite element modelling program of curved bellows is constructed using ANSYS APDL. The validity of numerical results obtained from ANSYS software is experimentally verified using the test model made by RP machine SLA 5000.

• 대한기계학회논문집A
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• 제40권11호
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• pp.913-918
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• 2016

자동차 엔진과 변속기 블록 등의 가공과정에서 잔류하는 기름때를 제거하기 위한 부품 세척장비는 정교한 제어장치 없이도 정확한 수류방향 절환이 원활히 이루지는 3 방향 절환밸브를 사용한다. 그러나, 밸브의 복잡한 유로 및 바텀플러그 형상으로 인해 유속변화가 심하게 발생하여 공동현상이 나타날 수 있다. 본 연구에서는 3 방향 절환밸브 내의 유동특성을 해석적으로 평가하였으며, 바텀플러그 하부에서 나타나는 공동현상을 공동화지표와 POC(Percent of cavitation)를 도입하여 정량화하였다. 공동현상의 저감을 위해 바텀플러그 형상을 매개변수화하고, 해석의 수렴성 개선과 해석시간을 단축시킬 수 있는 단순 유한요소모델을 이용하여 유동해석을 통한 형상최적설계를 실시하였다. 또한, 연구팀에서 보유하고 있는 유동시험설비와 ISA-RP75.23 규격에 맞게 제작된 시편을 이용하여 공동현상 가시화 실험을 실시하여 해석결과를 검증하였다.

• Industrial Engineering and Management Systems
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• 제1권1호
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• pp.87-92
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• 2002

A stochastic process {$A_n$, n = 1, 2, ...} is an arithmetic process (AP) if there exists some real number, d, so that {$A_n$ + (n-1)d, n =1, 2, ...} is a renewal process (RP). AP is a stochastically monotonic process and can be used for modeling a point process, i.e. point events occurring in a haphazard way in time (or space), especially with a trend. For example, the vents may be failures arising from a deteriorating machine; and such a series of failures id distributed haphazardly along a time continuum. In this paper, we discuss estimation procedures for an AP, similar to those for a geometric process (GP) proposed by Lam (1992). Two statistics are suggested for testing whether a given process is an AP. If this is so, we can estimate the parameters d, ${\mu}_{A1}$ and ${\sigma}^{2}_{A1}$ of the AP based on the techniques of simple linear regression, where ${\mu}_{A1}$ and ${\sigma}^2_{A1}$ are the mean and variance of the first random variable $A_1$ respectively. In this paper, the procedures are, for the most part, discussed in reliability terminology. Of course, the methods are valid in any area of application, in which case they should be interpreted accordingly.

• 한국산학기술학회논문지
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• 제11권6호
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• pp.2013-2020
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• 2010

본 연구에서는 기존의 전형적인 토스터가 갖는 개방된 출입구로 인한 열손실 발생, 이물질의 투입, 빵을 구운 정도를 확인할 수 없음에 대한 소비자 불만족 등의 문제점을 해결하기 위해 새로운 방식의 토스터인 폴더형 캡을 갖는 투명 토스터에 대한 모델링을 연구하였다. 먼저 1차 모델링을 수행하였으며, 이어서 RP제작을 통하여 모델링에 서 확인하지 못한 문제점을 수정 및 보완하여 2차 모델링을 수행하였다. 2차 모델링에서는 메커니즘분석을 통해 홀더 간섭을 확인하여 수정하였고, 이어서 3D 모델링, 어셈블리, 시뮬레이션 분석을 통하여 폴더형 캡의 기능을 갖는 투명 토스터를 최종 모델링하였다. 본 연구에서 사용한 3D 모델링 툴은 Pro/Engineer 4.0이며, 설계된 모델링은 폴더형 캡 의 기능을 갖추어 열손실을 최소화하고, 투명한 외부케이스로 구성되어 빵 굽는 과정을 육안으로 확인하게 함으로써 심미적 만족도를 향상시키는 기능을 갖춘 폴더형 캡의 투명 토스터이다.