메쉬 모델에 대한 아이소메트릭 형상 보간 방법

백승엽(Seung-Yeob Baek),이건우(Kunwoo Lee) (사)한국CDE학회 2014 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2014 No.2

Computing the natural-looking interpolation of different shapes is a fundamental problem of computer graphics. It is proved by some researchers that such an interpolation can be achieved by pursuing the isometry. In this paper, a novel coordinate system that is invariant under isometries is defined. The coordinate system can easily be converted from the global vertex coordinates. Furthermore, the global coordinates can be efficiently recovered from the new coordinates by simply solving two sparse least-squares problems. Since the proposed coordinate system is invariant under isometries, then transformations such as global rigid transformations, articulated posture deformations, or any other isometric deformations, do not change the coordinate values. Therefore, shape interpolation can be done in this framework without being affected by the distortions caused by the isometry.

숙신산 알킬 하프-아마이드 유도체의 합성 및 해수에 대한 방청성능

백승엽(Seung-Yeob Baek),김영운(Young-Wun Kim),정근우(Keun-Wo Chung),유승현(Seung-Hyun Yoo),김남균(Nam-Kyun Kim) 한국청정기술학회 2011 청정기술 Vol.17 No.4

암모니움 디티오카바메이트계 이온성 액체의 합성 및 내마모성능 (Ⅰ)

백승엽(Seung-Yeob Baek),김남균(Nam-Kyun Kim),신지훈(Jihoon Shin),정근우(Keunwo Chung),김영운(Young-Wun Kim) 한국트라이볼로지학회 2014 한국윤활학회지(윤활학회지) Vol.30 No.6

The friction-reducing properties of lubricants containing ionic liquids based on ammonium dithiocarbamate are studied. The ionic liquids are produced through the following two steps: the synthesis of sodium alkyl dithiocarbamates via the substitution reaction of dialkylamine and carbon disulfide and their subsequent conversion into ammonium dithiocarbamate-based ionic liquids through an ion-exchange reaction with a quaternary alkyl ammonium halide salt. The structures of the ionic liquids are characterized by NMR spectroscopy and Fourier transform infrared spectroscopy. The isolated yields of the ionic liquids, which are viscous and pale yellow, are approximately 92%. The Brookfield viscosities and pour points of the ionic liquids are determined. Further, their wear resistances are measured through the four-ball wear test and the Schwingung Reibung Verschleiss (oscillation, friction, wear) test. The wear scar diameter of the lubricants containing 1 wt of the quaternary alkyl ammonium dithiocarbamate-based ionic liquids (0.475-0.631 mm) is significantly lower than that of the base oil (0.825 mm), proving that the ammonium dithiocarbamate-based ionic liquids have good frictionreducing characteristics. However, these friction-reducing characteristics fade significantly after long-term storage, owing to the degradation of the ionic liquids.

삼각형 메쉬 상에서의 미분 연산자와 그 응용

백승엽(Seung-Yeob Baek),감동욱(Dong-Uk Kam),이건우(Kunwoo Lee) (사)한국CDE학회 2014 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2014 No.8

Solving partial differential equations (PDEs) on a manifold setting is frequently faced problem in CAD, CAM and CAE. However, unlikely to a regular grid, solutions for those problems on a triangular mesh are not available in general, as there are no well-established intrinsic differential operators. Considering that a triangular mesh is a powerful tool for representing a highly-complicated geometry, this problem must be tackled for improving the capabilities of many geometry processing algorithms. In this paper, we introduce mathematically well-defined differential operators on a triangular mesh setup, and show some examples of their applications. Through this, it is expected that many CAD/CAM/CAE application will be benefited, as it provides a mathematically rigorous solution for a PDE problem which was not available before.

숙신산 알킬 에스테르 유도체의 합성 및 윤활특성

백승엽 ( Seung Yeob Baek ),김영운 ( Young Wun Kim ),정근우 ( Keun Wo Chung ),유승현 ( Seung Hyun Yoo ),박수진 ( Su Jin Park ) 한국공업화학회 2011 공업화학 Vol.22 No.2

폴리올 에스테르 등의 에스테르 윤활제는 생분해성 및 윤활성능이 우수하여 금속가공유 및 유압작동유등의 윤활기유로 많이 사용되고 있다. 본 연구에서는 윤활성 향상제로 사용하기 위하여 알킬 무수 숙신산과 여러 가지 지방 알콜과의 축합반응을 행하여 알킬 숙시네이트 유도체를 합성하였다. 합성된 알킬 숙시네이트 유도체의 구조는 1H-NMR 및 FT-IR 스펙트럼으로 분석하였으며 GC 크로마토그램을 통하여 화합물의 순도를 확인하였다. 또한, 합성 유도체의 기본물성으로 점도특성, 굴절률, 전산가, 유동점 등을 측정하였으며 응용물성으로 윤활특성을 SRV 시험기와 4-ball 마모 시험기로 마찰계수(COF) 및 마모흔 직경(SRV WSD 및 4-ball WSD)을 측정하여 평가하였다. 기본물성 평가결과, 점도 특성, 굴절률 및 유동점은 알킬 숙시네이트 유도체에 함유된 알킬기의 탄소수가 증가할수록 높아졌으며 전산가는 0.2~4 mgKOH/g를 나타내어 금속가공유 및 유압작동유의 윤활제로 사용가능함을 알 수 있었다. 윤활성능 평가 결과, SRV WSD 0.391~0.689 mm, SRV COF 값은 0.110~0.138, 4-ball WSD 값은 0.49~0.55 mm를 나타내어 에스테르의 구조에 따라 차이를 나타내었다. 특히, SRV 시험에서 비교물질로 사용된 폴리올 에스테르인 TMPTO와 윤활성능을 비교하였을 때 SRV WSD 결과, 알킬기에 따라 다른 차이를 나타냈지만 비교물질에 비해 비교적 우수한 값으로, SRV COF 결과, 알킬기에 대한 영향을 받지 않고 비교물질에 비해 약간 떨어지는 값을 나타내었다. In this paper, a series of alkyl succinic acid esters for base oil were synthesized by condensation reaction of succinic anhydride and fatty alcohol. The structures of the synthesized esters were confirmed by 1 H-NMR, FT-IR spectrum and GC analysis. Basic properties of esters such as kinematic viscosity (KV), refractive index (RI), total acid number (TAN) and pour points were measured and lubricating properties such as SRV wear scar diameter (SRV WSD), fraction coefficient (COF) and 4-ball wear (4-ball WSD) were also evaluated. As the results of basic properties, KV, RI and pour point of synthetic esters increased as the carbon chain of the esters increased. Measurement value of total acid number (TAN) was indicated between 0.2~4 mgKOH/g, and that metal working fluids and pressure working oils are acceptable to use as base oil. Also, lubricating properties of the esters showed as follows: 0.391~0.689 mm of SRV WSD, 0.110~0.138 of SRV COF and 0.49~0.55 mm of 4-ball WSD depended on the structure of the esters. In a comparison on the lubrication capacity of the SRV test based on polyester TMPTO, SRV WSD result showed that a better performance caused by the alkyl group. On the other hand, SRV COF test was not influenced of the alkyl group which the capacity of the lubricant was sightly diminished than the comparison material, regardless of the alkyl group.

국내 한의학 학술지에 발표된 탈모 실험 논문에 대한 고찰

백승엽 ( Seung Yeob Baek ),임채광 ( Chae Kwang Im ),김광중 ( Kwang Joong Kim ) 대구한의대학교 제한동의학술원 2014 東西醫學 Vol.39 No.4

We searched for the literature of alopecia experiments for the systemic analysis on the research situations of alopecia experiments published in the journal of oriental medicine to understand the search trend in the area of hair and alopecia. prepare the basis for the in erests and basis on hair and alopecia in be oriental medicine area and above that, to support for the applications in the clinics through this. As a result. we found 26 literatures on the experiments about the alopecia treatment and hair growth and performed a systemic analysis on it to came to the following conclusions. 1. In the classification by pathologic model. the literatures on the experimen s inducing alopecia on C57BL/6N mice by animal hair clipper and depilatory took the biggest portion with 9.2.

메쉬 모델에 대한 아이소메트릭 형상 보간 방법

백승엽(Seung-Yeob Baek),이건우(Kunwoo Lee) (사)한국CDE학회 2014 한국CDE학회 논문집 Vol.19 No.2

Computing the natural-looking interpolation of different shapes is a fundamental problem of computer graphics. It is proved by some researchers that such an interpolation can be achieved by pursuing the isometry. In this paper, a novel coordinate system that is invariant under isometries is defined. The coordinate system can easily be converted from the global vertex coordinates. Furthermore, the global coordinates can be efficiently recovered from the new coordinates by simply solving two sparse least-squares problems. Since the proposed coordinate system is invariant under isometries, then transformations such as global rigid trans-formations, articulated posture deformations, or any other isometric deformations, do not change the coordinate values. Therefore, shape interpolation can be done in this framework without being affected by the distortions caused by the isometry.

삼각형 메쉬 상에서의 미분 연산자와 그 응용

백승엽(Seung-Yeob Baek),감동욱(Dong-Uk Kam),이건우(Kunwoo Lee) (사)한국CDE학회 2015 한국CDE학회 논문집 Vol.20 No.1

Solving partial differential equations (PDEs) on a manifold setting is frequently faced problem in CAD, CAM and CAE. However, unlikely to a regular grid, solutions for those problems on a triangular mesh are not available in general, as there are no well-established intrinsic differential operators. Considering that a triangular mesh is a powerful tool for representing a highlycomplicated geometry, this problem must be tackled for improving the capabilities of many geometry processing algorithms. In this paper, we introduce mathematically well-defined differential operators on a triangular mesh setup, and show some examples of their applications. Through this, it is expected that many CAD/CAM/CAE application will be benefited, as it provides a mathematically rigorous solution for a PDE problem which was not available before.

Shape Terra: 열지속특성을 응용한 CAD 피쳐 인식 도구

Ramy Harik,백승엽(Seung-Yeob Baek),Barend-Jan Van Bruchem,Michel Van Tooren (사)한국CDE학회 2015 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2015 No.동계

In many CAD/CAM/CAPP applications, recognizing geometric features is of ubiquitous need. Recognizing and analyzing geometric features in a mechanical part will augment manufacturing knowledge within the product development process. Although feature recognition is progressing steadily in many computer graphics applications, it is still an undiscovered area in mechanical design; we are still lacking a feasible solution for feature recognition that can be applied specifically to the CAD parts. In this paper, we will present Shape Terra; our recent advance in CAD feature recognition technology. Shape Terra identifies the typical mechanical features from a given CAD part by utilizing the findings of traditional heat transfer theory, which says that salient features tend to retain the heat more whereas flat surfaces tend to lose it faster. Furthermore, each feature is analyzed and assigned with its meaning, such as design parameters, manufacturability, and so on. Various CAD/CAM/CAPP applications will profit from such information.

Mesh상에서 측지선을 이용한 지역 매개화

김대욱(Dae-Wook Kim),백승엽(Seung-Yeob Baek),이건우(Kunwoo Lee) 대한기계학회 2014 대한기계학회 춘추학술대회 Vol.2014 No.11

As a 3D scanner technology is getting developed, it is adapted on various areas, especially human body scanning or face modeling. In the past, Non-rigid registration is used for 3D scanning; however, this process is slow because it needs feature points before matching a scanned model with a templet model. There are a plenty of researches on dense registration which uses a point-to-point matching method in meshes. Using geodesics on manifold, the point-to-point matching information is acquired easily.