• International Journal of CAD/CAM
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• 제9권1호
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• pp.71-77
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• 2010

Various applications, such as mesh composition and model repair, ask for a natural stitching for polygonal surfaces. Unlike the existing algorithms, we make full use of the information from the two feature lines to be stitched up, and present an accurate stitching method for polygonal surfaces, which minimizes the error between the feature lines. Given two directional polylines as the feature lines on polygonal surfaces, we modify the general placement method for points matching and arrive at a closed-form solution for optimal rotation and translation between the polylines. Following calculating out the stitching line, a local surface optimization method is designed and employed for postprocess in order to gain a natural blending of the stitching region.

• Journal of Ship and Ocean Technology
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• 제9권1호
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• pp.47-63
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• 2005

In the present study, we suggest a new method for designing complex ship hull forms with multiple domain B-spline surfaces accounting for their topological arrangement, where all subdomains are fully defined in terms of form parameters, e.g., positional, differential and integral descriptors. For the construction of complex hull forms, free-form elementary models such as forebody, afterbody and bulbs are united by Boolean operation and blending surfaces in compliance with the sectional area curve (SAC) of the whole ship. This new design process in this paper is called Sectional Area Curve-Balanced Parametric Design (SAC-BPD).

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2018년도 추계 학술논문 발표대회
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• pp.52-53
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• 2018

As a result of exposing the concrete at 1 and 6 atm in order to evaluate the salt resistance of the pressurized marine concrete, the pressure resulted in promoting the chloride ion penetration of the concrete. Particularly, the amount of water soluble chloride in the surface area tends to increase rapidly, and this cause is considered to be highly correlated with the size of the capillary pores of the concrete. On the other hand, the blending of blast furnace slag was effective to increse chloride attack resistibility even under the pressure.

• 전산구조공학
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• 제4권1호
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• pp.109-120
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• 1991

이 논문은 유한요소해석의 전처리를 위한 3차원 구조물의 가하학적 모델링 방법을 제안하였다. 여기서 제안한 모델링 체계에 의하면 구조물의 모델은 조절점, 곡선, 곡면 및 입체의 계층적 구성에 따라서 단계적으로 형성된다. 혼성함수와 경계표현법을 기본으로하는 여러가지 곡면 및 입체의 모델링 방법을 유한요소망 발생에 적합하도록 체계화하였으며, 모델합성 및 연산방법을 제시하였다. 이를 바탕으로 새로운 유한요소해석 전처리 프로그램을 개발하였다.

• Journal of Electrical Engineering and Technology
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• 제13권5호
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• pp.1996-2003
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• 2018

In this paper, the design and characteristic analysis of a novel single-phase hybrid switched reluctance motor (HSRM) for the purpose of replacing the universal motor in commercial blenders are presented. The proposed motor is easy to manufacture due to its simple yet robust structure with minimized power switches and no torque dead-zone. Moreover, the proposed HSRM is able to deliver a high starting torque as a requirement for blending hard food or even ice. The stator has permanent magnets (PMs) mounted on its inner surface and the rotor has a wide pole arc and salient poles that contribute to its high starting torque profile and the elimination of the torque dead-zone. Finite element method (FEM) is used to analyze the characteristic of the proposed motor. Finally, the prototype is manufactured and its performance is verified through experiments.

• Computers and Concrete
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• 제10권1호
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• pp.19-33
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• 2012

The performance of a concrete is significantly influenced by its mixture proportion and the coating thickness on aggregate surface. The concrete in this study is designed by estimating the blending ratio of aggregate using a densified mixture design algorithm (DMDA) based on an ideal grading curve and estimating the paste volume as the sum of the amount of paste needed to provide an assigned coating paste thickness. So as to obtain appropriate concrete amount, and thus can accurately estimate the property of concrete. Deduction of this mix design formula is simple and easy understanding, and meanwhile to obtain result is fast. This estimation model of mix design is expected to reward to industry and effectively upgrade concrete quality.

• 대한조선학회논문집
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• 제35권2호
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• pp.51-62
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• 1998

본 연구에서는 공동수조(Cavitation Tunnel) 실험용 모형프로펠러의 5축 가공을 위해 Windows NT와 PC 환경하에서 작동하는 CAD/CAM 시스템을 개발하였다. 본 시스템은 그 성격에 따라 크게 4가지의 모듈로 구성되어 있다. 먼저, 프로펠러 설계를 위해 기존에 사용하고 있던 텍스트 위주의 S/W(Text based S/W)를 그래픽화 하여 통합함으로써 설계의 효율을 향상시켰다. 설계의 결과로 출력되는 점 데이터는 NURBS(Non-Uniform Rational B-Spline) 방법을 이용하여 복합곡면 (Composite Surface)으로 모델링하였고 가공은 황삭, 중삭, 정삭 및 잔삭으로 수행하였다. 각각의 경우에 있어서 공구와 공작물의 충돌 및 간섭을 체크하여 공구경로를 산출하였으며 그것을 역기 구학 해석하여 NC 데이터로 변환하였다. 또한, 가공의 상태를 화면상에서 검증하기위해 공구 및 공작물을 그래픽화하여 NC 데이터를 검증할 수 있도록 하였다. 끝으로 5축 가공의 가공 효율을 최대화하기 본 연구에서는 공동수조 실험용 모형프로펠러의 5축 가공을 위해 Windows NT와 PC 환경하위해 실험을 통하여 최적의 절삭조건을 선정하고 이를 시스템내에 데이터베이스화 함으로써 설계부터 가공까지를 자동으로 수행할 수 있는 시스템으로 구축하였다.

• Macromolecular Research
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• 제9권2호
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• pp.107-115
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• 2001

Poly(L-lactide-co-glycolide)(PLGA) was blended with poly[$\omega$-methacryloyloxyethyl phospho-rylcholine-co-ethylhexylmethacrylate (PMEH)] (PLGA/PMEH) to endow with new functionality i.e., to improve the cell-, tissue- and blood-compatibility. The characteristics of surface properties were investigated by measurement of contact angle goniometer, Fourier-transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR) and electron spectroscopy for chemical analysis (ESCA). NIH/3T3 fibroblast and bovine aortic endothelial cell were cultured on control and PLGA/PMEH surfaces for the evaluation of ceil attachment and proliferation in terms of surface functionality such as the concentration of phosphoryl-choline. Also, the behavior of platelet adhesion on PLGA/PMEH was observed in terms of the surface functionality. The contact angles on control and PLGA/PMEH surfaces decreased with increasing PMEH content from 75$^{\circ}$ to about 43$^{\circ}$. It was observed from the FTIR-ATR spectra that phosphorylcholine groups are gradually increased with increasing blended amount of MPC. The experimental P percent values from ESCA analysis were more 3.28∼7.4 times than that of the theoretical P percent for each blend films. These results clearly indicated that the MPC units were concentrated on the surface of PLGA/PMEH blend. The control and PLGA/PMEH films with 0.5 to 10.0 wt% concentration of PMEH were used to evaluate cell adhesion and growth in terms of phosphorylcholine functionality and wettability. Cell adhesion and growth on PLGA/PMEH surfaces were less active than those of control and both cell number decreased with increasing PMEH contents without the effect of surface wettability. It can be explained that the fibronectin adsorption decreased with an increase in the surface density of phosphorylcholine functional group. One can conclude the amount of the protein adsorption and the adhesion number of cells can be controlled and nonspecifically reduced by the introduction with phosphorylcholine group. Morphology of the adhered platelets on the PLGA/PMEH surface showed lower activating than control and the number of adhered platelets on the PLGA/PMEH sample decreased with increasing the phosphorylcholine contents. The amount of fibrinogen adsorbed on the PLGA/PMEH surface demonstrated that the phospholipid polar group played an important role in reducing protein adsorption on the surface. In conclusion, this surface modification technique might be effectively used PLGA film and scaffolds for controlling the adhesion and growth of cell and tissue, furthermore, blood compatibility of the PLGA was improved by blending of the MPC polymer for the application of tissue engineering fields.

• Korean Chemical Engineering Research
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• 제50권4호
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• pp.614-620
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• 2012

Poly (carbonate diol), isophrone diisocyanate와 dimethylol propionic acid로부터 제조된 폴리우레탄 prepolymer의 말단 NCO 기를 aniline으로 capping시켜 aniline terminated waterborne polyurethane dispersion (ATPUD)을 합성하였다. 이 ATPUD와 순수한 waterborne polyurethane dispersion (PUD)을 각각 전도성 고분자인 polystyrene sulfonate로 도핑된 poly (3,4-ethylenedioxythiophene)[PEDOT/PSS]과 블렌딩시켜 대전방지용 코팅 용액을 제조한 후, 이것을 polycarbonate 기재 위에 도포하여 코팅 도막을 형성하였다. PEDOT/PSS가 2.5 g 이하로 적당량 첨가된 경우에는 ATPUD로 제조된 코팅 도막의 표면저항 값은 $1.0{\times}10^{11}{\sim}2.5{\times}10^8{\Omega/cm^2$로 순수한 PUD로부터 제조된 코팅 도막의 $5.0{\times}10^{11}{\sim}6.3{\times}10^9{\Omega}/cm^2$ 보다 우수한 전기전도도를 나타내었다. 그러나 PEDOT/PSS가 3.0 g으로 과량 첨가된 경우에는 ATPUD로부터 제조된 코팅 도막과 PUD로부터 제조된 코팅 도막은 비슷한 전기전도도를 나타내었다.

• 대한화학회지
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• 제12권1호
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• pp.4-11
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• 1968

With the selected emulsifiers for the emulsion polymerization of methyl methacrylate, the HLB of the emulsifier in the reaction system has been studied on the effect of the ratio of tetra sodium-N-(1,2-dicarboxy ethyl)-N-octadecyl sulfosuccinamate(Aerosol 22) to polyethylene glycol nonyl phenyl ether (Noigen EA 160), and also sodium lauryl sulfate(Quolac EX-UB), Disodium-N-octadecyl sulfosuccinamate (Aerosol 18) and Aerosol 22 as emulsifiers having various hydrophilic groups in the molecules have been studied. Results are as follows; 1) The viscosity of the emulsions and the molecular weight of the polymers have maximum values at a constant HLB value of emulsifiers, but their stabilities show minimum point at the value with the titration with the three kinds of mono, bi, tri-valent electrolytes. These results are agreed on the theory of Greth & Wilson in which the properties of polymer emulsions depend upon the HLB system of emulsifiers. 2) The viscosity of the emulsions and the molecular weights of the produced polymers increase more in the case of blending of Aerosol 22 to Noigen EA-160 than of the separate using. 3) The coagulation effects of the divalent electrolytes($ex,\;Ca^{++},\;Zn^{++}$) are contrast to the effects of monovalent($ex,\;Na^+$) and trivalent($ex,\;Al^{+++}$) in the emulsions with Aerosol 18 or Aerosol 22 which have more than two hydrophilic groups. It seems that the stability of the O/W emulsions by electrolytes is directly related to the parameters of surface physical chemistry such as surface geometry of surface chemical constitution of polymer particles.