3D 모델 기반 기하처리를 이용한 치아 임플란트 식립 계획 수립 및 유한요소분석

박형욱(Hyungwook Park),박철우(Chulwoo Park),박상진(Sangjin Park),김명수(Myung-Soo Kim),박형준(Hyungjun Park) (사)한국CDE학회 2012 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2012 No.2

치아 임플란트 시술의 성공률을 높이기 위해서는 시술 전 적절한 식립 계획을 수립하는 것이 매우 중요하다. 최근에는 의료영상 및 3D 데이터 기반 S/W가 시술계획 수립 과정에 널리 활용되고 있으나, 식립 위치와 방향 선정이 시술자 경험과 주관적 판단에 의존되어 상당한 편차가 존재한다. 본 논문에서는 식립 위치 근처에 존재하는 주변치아 및 구강에 따라 3D 모델의 기하학적 처리를 통해 임플란트 식립 위치 및 방향을 결정하고, 이를 유한요소분석을 통해 입증함으로써 보다 일관된 식립 계획을 수립하는 방안을 제시한다. 제안된 방안에서는 시술부위의 주변 치아들에 대해 PCA 알고리즘을 적용하여 얻어진 최소포함원기등(Minimum Enclosing Cylinder)을 이용하여 식립위치 및 방향을 결정한다. 시술부위 주변 원기둥의 윗면 중심점과 원기둥 반경을 고려하여 식립 위치를 결정하고, 주변 원기둥의 중심축에 가중치를 고려한 평균을 통해 식립 방향을 결정한다. 또한 시술부위 주변 원기둥들과 신경관 모델 간의 간섭을 고려하여 시술부위 원기둥의 최대 반경과 최대 길이를 추정한 후, 이를 임플란트 크기 및 유형 선정에 활용한다. 유한요소분석을 통해 식립 계획 정보의 적합성을 확인한 다음, 식립계획 정보를 토대로 식립보조도구(surgical stents)의 3D 모델을 생성한다. 최종적으로 3D 치아 임플란트 시술 시뮬레이션을 수행함으로써 제시된 방안이 치아 임플란트 시술용 교육컨텐츠에 유용하게 활용됨은 물론 식립계획 수립을 위한 유용한 정보를 제공할 수 있음을 보인다.

Tangible Augmented Prototyping of Digital Handheld Products

Hyungjun Park,Hee-Cheol Moon (사)한국CDE학회 2007 한국CAD/CAM학회 국제학술발표 논문집 Vol.2007 No.8

Adaptive B-spline volume representation of measured BRDF data for photorealistic rendering

Park, Hyungjun,Lee, Joo-Haeng Society for Computational Design and Engineering 2015 Journal of computational design and engineering Vol.2 No.1

Measured bidirectional reflectance distribution function (BRDF) data have been used to represent complex interaction between lights and surface materials for photorealistic rendering. However, their massive size makes it hard to adopt them in practical rendering applications. In this paper, we propose an adaptive method for B-spline volume representation of measured BRDF data. It basically performs approximate B-spline volume lofting, which decomposes the problem into three sub-problems of multiple B-spline curve fitting along u-, v-, and w-parametric directions. Especially, it makes the efficient use of knots in the multiple B-spline curve fitting and thereby accomplishes adaptive knot placement along each parametric direction of a resulting B-spline volume. The proposed method is quite useful to realize efficient data reduction while smoothing out the noises and keeping the overall features of BRDF data well. By applying the B-spline volume models of real materials for rendering, we show that the B-spline volume models are effective in preserving the features of material appearance and are suitable for representing BRDF data.

Tangible AR interaction based on fingertip touch using small-sized non-square markers

Park, Hyungjun,Jung, Ho-Kyun,Park, Sang-Jin Society for Computational Design and Engineering 2014 Journal of computational design and engineering Vol.1 No.4

Although big-sized markers are good for accurate marker recognition and tracking, they are easily occluded by other objects and deteriorate natural visualization and level of immersion during user interaction in AR environments. In this paper, we propose an approach to exploiting the use of rectangular markers to support tangible AR interaction based on fingertip touch using small-sized markers. It basically adjusts the length, width, and interior area of rectangular markers to make them more suitably fit to longish objects like fingers. It also utilizes convex polygons to resolve the partial occlusion of a marker and properly enlarges the pattern area of a marker while adjusting its size without deteriorating the quality of marker detection. We obtained encouraging results from users that the approach can provide better natural visualization and higher level of immersion, and be accurate and tangible enough to support a pseudo feeling of touching virtual products with human hands or fingertips during design evaluation of digital handheld products.

Knowledge-Based CNC Torch Path Generation for Laser Cutting of Planar Shapes

Hyungjun Park,Dong-Gyu Ahn (사)한국CDE학회 2005 한국CAD/CAM학회 국제학술발표 논문집 Vol.2005 No.8

Simultaneous improvement of the dielectric constant and leakage currents of ZrO₂ dielectrics by incorporating a highly valent Ta⁵⁺ element

Park, Bo-Eun,Oh, Il-Kwon,Park, Jong Seo,Seo, Seunggi,Thompson, David,Kim, Hyungjun The Royal Society of Chemistry 2018 Journal of Materials Chemistry C Vol.6 No.36

<P>Dynamic random access memory (DRAM) is reaching the scaling limit owing to the requirements for a high capacitance density and low leakage current of metal-insulator-metal (MIM) capacitors. We investigated the Ta-doped ZrO2 dielectric as a novel high-<I>k</I> candidate, utilizing the precise control of Ta-doping concentration using the atomic layer deposition (ALD) supercycle process. We systematically studied the chemical composition and crystal structure of ALD Ta-doped ZrO2 and its effects on the electrical properties of MIM capacitors. It was shown that ZrO2 becomes more stoichiometric with the introduction of Ta, which is attributed to the suppression of oxygen vacancy (VO) formation. The change in the atomic arrangement due to the substitution of Zr with Ta and the reduction of VO enhances the crystallinity of the cubic phase and causes a decrease in the molar volume of the ZrO2 films. As a result of the change in the crystal structure along with the high dielectric polarizability of Ta, the dielectric constant of ALD Ta-doped ZrO2 increases by up to 80% compared to that of undoped ZrO2 films. Moreover, the reduction of the VO species suppresses the emission of the carriers, which lowers the leakage current density by two orders of magnitude in the Ta-doped ZrO2 films as compared to that in the undoped ZrO2 films. In general, the dielectric constant and leakage currents have a trade-off relationship in a single high-<I>k</I> dielectric system. Consequently, proper doping of Ta into ZrO2 using ALD is a promising solution to overcome the technical limits of conventional high-<I>k</I> dielectrics.</P>

A new approach for optimal single biarc fitting

Hyungjun Park(박형준) (사)한국CDE학회 2004 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2004 No.2

<i>In-Situ</i> Synchrotron X-Ray Scattering Study of Thin Film Growth by Atomic Layer Deposition

Park, Yong Jun,Lee, Dong Ryeol,Lee, Hyun Hwi,Lee, Han-Bo-Ram,Kim, Hyungjun,Park, Gye-Choon,Rhee, Shi-Woo,Baik, Sunggi American Scientific Publishers 2011 Journal of nanoscience and nanotechnology Vol.11 No.2

<P>We report an atomic layer deposition chamber for in-situ synchrotron X-ray scattering study of thin film growth. The chamber was designed for combined synchrotron X-ray reflectivity and two-dimensional grazing-incidence X-ray diffraction measurement to do a in-situ monitoring of ALD growth. We demonstrate ruthenium thermal ALD growth for the performance of the chamber. 10, 20, 30, 50, 70, 100, 150 and 250-cycled states are measured by X-ray scattering methods during ALD growth process. Growth rate is calculated from thickness values and the surface roughness of each state is estimated by X-ray reflectivity analysis. The crystal structure of initial growth state is observed by Grazing-incidence X-ray diffraction. These results indicate that in-situ X-ray scattering method is a promising analysis technique to investigate the initial physical morphology of ALD films.</P>

Note on Augmented Reality-based Tangible Interaction using a Finger Fixture

Park Hyungjun,Hee-Cheol Moon (사)한국CDE학회 2010 한국CAD/CAM학회 국제학술발표 논문집 Vol.2010 No.8

In this paper, we propose an augmented reality (AR) based tangible interaction using a finger fixture for virtual evaluation of digital handheld products. To realize tangible interaction between a user and a product in a computer-vision based AR environment, we use two types of tangible objects: a product-type object and a finger fixture. The product-type object is used to acquire the position and orientation of the product, and the finger fixture is used to recognize the position of a finger tip. The two objects are fabricated by rapid prototyping (RP) technology and AR markers are attached to them. The finger fixture is designed to satisfy various requirements with an ultimate goal that the user holding the finger fixture in his or her index finger can create HMI events by touching specified regions (buttons or sliders) of the product-type object with the finger tip. After performing the design evaluation of several handheld products using the proposed AR-based tangible interaction, we received highly encouraging feedback from users since the proposed interaction is intuitive and tangible enough to provide a feeling like manipulating products with human hands.

Phase-controlled synthesis of SnO_x thin films by atomic layer deposition and post-treatment

Park, Bo-Eun,Park, Jaehong,Lee, Sangyoon,Lee, Sanghun,Kim, Woo-Hee,Kim, Hyungjun Elsevier 2019 APPLIED SURFACE SCIENCE - Vol.480 No.-

<P><B>Abstract</B></P> <P>Tin oxide (SnO<SUB>x</SUB>) is a promising oxide semiconductor due to the distinct properties of n-type SnO<SUB>2</SUB> and p-type SnO based on its stoichiometry. However, the stoichiometry control of SnO<SUB>x</SUB> remains challenging due to the thermodynamic instability of SnO. In the study, we focus on establishing the controllable stoichiometry of SnO<SUB>x</SUB> via atomic layer deposition (ALD) and subsequent treatment. The controllable synthesis of SnO<SUB>2</SUB> and SnO is investigated by multiple analyses involving the chemical composition, crystal structure, and band structure. The ALD SnO<SUB>x</SUB> is composed mostly of Sn<SUP>4+</SUP> O bonds with intrinsic oxygen vacancies and is transformed into crystalline SnO<SUB>2</SUB> phase via post-annealing. The refractive index (~1.8) and optical bandgap energy (~3.6 eV) of ALD SnO<SUB>x</SUB> correspond to those of SnO<SUB>2</SUB>. Post-deposition treatment with H<SUB>2</SUB> plasma enables the effective transformation of SnO<SUB>2</SUB> into SnO due to the easy penetration of H<SUP>+</SUP> ion into the film and de-bonding of SnO via ion bombardment. The transformed SnO exhibits a significant amount of Sn<SUP>2+</SUP> O bonds with a refractive index of 2.8 and optical bandgap energy of ~2.9 eV. Specifically, the transformed SnO exhibits promise as an oxide semiconductor because it exhibits excellent stability with respect to re-oxidation into SnO<SUB>2</SUB> or further reduction into Sn metal. The present study advances practical applications that require a stable p-n junction through n-type SnO<SUB>2</SUB> and p-type SnO in various forms of device architectures.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Formation of SnO<SUB>2</SUB> and SnO was controlled by atomic layer deposition and post-process. </LI> <LI> Chemical composition, crystal structure, and band structure of SnO<SUB>x</SUB> were analyzed. </LI> <LI> As-deposited SnO<SUB>x</SUB> exhibits typical characteristics of SnO<SUB>2</SUB>. </LI> <LI> Post-deposition treatment with H<SUB>2</SUB> plasma effectively transforms SnO<SUB>2</SUB> into SnO. </LI> <LI> Transformed SnO is stable against re-oxidation or reduction during post-process. </LI> </UL> </P>