• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2009년도 IWAIT
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• pp.784-789
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• 2009

We propose a novel method of procedurally generating climbing plants using L-systems. The goal of this research is to generate geometry for 3D-modelers, where procedurally generated content is used as a base for the final design. The algorithm is fast and efficiently simulates external tropisms such as gravitropism and heliotropism, as well pseudo-tropisms. The structure of the generated climbing plants is discretized into strings of particles expressed using L-systems. The tips of the plant extend the branches by adding particles in its path, forming internodes. A climbing heuristic has been developed that uses the environment as leverage when the plant is climbing, and effectively covers objects on which it grows. A fast method that sprouts leaves on the surface on which the plant is growing has also been developed, along with a heuristic that simulates the decrease in length, radius and leaf size.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.84.1-84.1
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• 2010

Since the discovery of the carbon nanotube(CNTs), they have attracted much attention because of unique properties that may impact many fields of science and technology. The considerable properties of CNTs include high surface area, outstanding thermal, electrical conductivity and mechanical stability. However, uniform deposition of Pt nanoparticles on carbon surface remains inaccessible territory because of the inert carbon surface. In this study, we prepared directly oriented CNTs on carbon paper as a catalyst support in cathode electrode. carbon surface was functionalized using aryl diazonium salt for increasing adhesion of Ni particles which is precursor for growing CNTs. For fabricate electrode, CNTs on carbon paper were grown by chemical vapor deposition using Ni catalyst and Pt nanoparticles were deposited on CNTs oriented carbon paper by polyol method. The performance was measured using Proton electrolyte Membrane Fuel Cell(PEMFC). The structure and morphology of the Pt nanoparticles on CNTs were characterized by Scanning electron Microscopy(SEM) and Transmission electron Microscopy (TEM). The average diameter of Pt nanoparticles was 3nm.

• Journal of Photoscience
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• 제10권2호
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• pp.199-202
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• 2003

The relationship between the morphology of nanostructured TiO$_2$ films and the photo-injected electron transport has been investigated using intensity-modulated photocurrent spectroscopy (IMPS). For this purpose, three different TiO$_2$ films with 5 ${\mu}{\textrm}{m}$ thickness are prepared: The rutile TiO$_2$ film with 500 nm-sized cluster-like spherical bundles composed of the individual needles (Tl), the rutile TiO$_2$ film made up of non-oriented, homogeneously distributed rod-shaped particles having a dimension of approximately 20${\times}$80 nm (T2), and the anatase TiO$_2$ film with 20 nm-sized spherically shaped particles (T3). Cross sectional scanning electron micrographs show that all of the TiO$_2$films have a quite different particle packing density: poorly packed Tl film, loosely packed T2 film and densely packed T3 film. The electron transport is found to be significantly influenced by film morphology. The effective electron diffusion coefficient D$_{eff}$ derived from the IMPS time constant is an order of magnitude lower for T2 than for T3, but the D$_{eff}$ for the Tl sample is much lower than T2. These differences in the rate of electron transport are ascribed to differences in the extent of interparticle connectivity associated with the particle packing density.ity.

• 한국응용과학기술학회지
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• 제35권2호
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• pp.350-356
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• 2018

수산화인회석은 생체적합성이 뛰어나기 때문에 생체재료로 사용되고 있다. 본 연구에서는 온도, 농도, pH를 조절하여 인산수소칼슘 중간체의 가수분해반응을 통해 c면이 배향된 수산화인회석을 합성하였다. 염기조건에서 전구체의 농도가 낮을 경우 막대 형태의 수산화인회석 결정이 모여 불규칙한 형태의 입자를 만들었고 농도가 높을 경우 수산화인회석결정의 c면이 노출된 판 형태의 입자를 만들었으며 이에 따라 입자의 제타전위 차가 3 mV가 되었다. 생성물의 물리화학적 특성은 XRD, SEM, FT-IR, 제타전위측정기를 통해 평가하였다.

• 한국식품과학회지
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• 제47권6호
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• pp.733-737
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• 2015

나노 $TiO_2$ 코팅 필름은 식품 포장재에서 많이 사용하는 PU와 PVB-cellulose 두 가지 바인더에 나노 콜로이달 $TiO_2$를 각각 3%와 5%의 농도로 혼합제조하여 OPP 필름에 코팅하였다. PVB 바인더로 코팅한 필름이 PU 바인더(3%와 5%)보다 불균일하게 필름에 코팅이 되었다. 그러나 청변현상 방지 실험과 광분해 실험에서는 필름 코팅 상태와 상관없이 선도 유지 효과가 나타났다. MB를 사용한 광분해성 효과 측정 실험에서 나노 $TiO_2$의 광촉매 반응으로 인해 초기 30분부터 MB가 분해되는 것을 확인하였고, 콩나물 포장재 내에서 혐기성 호흡으로 발생하는 이취인 acetaldehyde는 나노 $TiO_2$ 코팅 필름이 대조구에 비해 농도가 감소하는 것을 확인하였다. 따라서 개발된 나노 $TiO_2$ 코팅 필름으로 콩나물의 청변 현상과 이취 제거로 인해 콩나물의 보관 수명을 연장할 수 있었다.

• Interaction and multiscale mechanics
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• 제2권1호
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• pp.45-68
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• 2009

An aim of the study is to develop an efficient numerical simulation technique that can handle the two-scale analysis of fluid permeation filters fabricated by the partial sintering technique of small spherical ceramics. A solid-fluid mixture homogenization method is introduced to predict the mechanical characters such as rigidity and permeability of the porous ceramic filters from the micro-scale geometry and configuration of partially-sintered particles. An extended finite element (X-FE) discretization technique based on the enriched interpolations of respective characteristic functions at fluid-solid interfaces is proposed for the non-interface-fitted mesh solution of the micro-scale analysis that needs non-slip condition at the interface between solid and fluid phases of the unit cell. The homogenization and localization performances of the proposed method are shown in a typical two-dimensional benchmark problem whose model has a hole in center. Three-dimensional applications to the body-centered cubic (BCC) and face-centered cubic (FCC) unit cell models are also shown in the paper. The 3D application is prepared toward the computer-aided optimal design of ceramic filters. The accuracy and stability of the X-FEM based method are comparable to those of the standard interface-fitted FEM, and are superior to those of the voxel type FEM that is often used in such complex micro geometry cases.

• Biotechnology and Bioprocess Engineering:BBE
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• 제5권5호
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• pp.332-339
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• 2000

Experimental and theoretical works were performed for the separation of large polyelectrolytes such as DNA in the column packed with gel particles under an electric field. This paper shows how intraparticle convection effects the separation of DNAs in the column because DNAs quickly oriented through the pores in the field direction. Dimensionless transient mass balance equations were derived considering diffusion and electrophoretic convection. The separation criteria is theoretically studied using two different Peclet numbers in the fluid and solid phases and these criteria were verified uing two different DNAs by electrophoretic mobilities measured experimentally, showing how the separation position of DNAs varies in the column according to values of Pe(sub)f/Pe(sub)g of individual DNA. Governing equations are simultaneously solved by operator theoretic and characteristic methods to yield the column response.

• 한국세라믹학회지
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• 제33권9호
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• pp.985-994
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• 1996

The initiation and growth of $\alpha$-Al2O3/metal composites by the directed oxidation of molten commercial AlZnMg-alloy at 1223-1423K were investigated. Spontaneous bulk growth did not occur on the alloy alone. but the uniform initiation and growth of the composite were obtained by putting a thin layer of SiO2 particles on the surface of the alloy. Without SiO2 the external surface of the oxide layer was convered by MgO and MgAl2O4. But with the SiO2 reaction initiate the porous ZnO layers were found on the growth surface. The higher process temperature yielded a lower metal content. The oxidation product of $\alpha$-Al2O3 was found to be oriented with c-axis parallel to th growth direction. The growth rates increased with temperature and the apparent activation energy was 111.8 kJ/mol.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2015년도 춘계학술발표대회
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• pp.875-877
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• 2015

본 논문은 위치기반 동역학 방법에 사용되는 3D물체를 근사화하기 위한 방향성 파티클 배치방법을 소개한다. 물체 매쉬를 분할하고 각 분할된 내부에 파티클을 채우는 배치 방법을 사용하면 물체의 표면에 여러 개의 파티클을 무작위로 배차하는 기존 방법보다 방향성 파티클의 개수를 줄일 수 있다. 시뮬레이션 실험을 통해 본 논문에서 제안한 방법으로 배치한 파티클 구조가 기존 방법으로 배치한 파티클 구조에 비해 보다 빠르게 시뮬레이션을 계산할 수 있다는 것을 확인하였다.

• Applied Microscopy
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• 제24권3호
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• pp.46-54
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• 1994

오돈토글로썸 윤문 바이러스(ORSV)에 감염된 한국 자생춘란(Cymbidium goeringii) 초박절편의 전자현미경 관찰에서 ORSV 입자들은 집적되거나 환형상 평면구조로 다양한 크기의 불규칙적인 응집된 다발상들이 관찰되었다. 바이러스 입자들은 원형질체에서 다수 존재하였고, 세포벽과 원형질막 사이에서도 존재하였으며, 이들은 주로 응집된 평행상과 불규칙적인 산재된 형태로 관찰되었다. X-체 및 paramural body는 원형질막 주변에 존재하였고 액포와 유사한 낭상 구조체에 싸여있었다. 바이러스에 감염된 조직의 세포벽은 확장되어 있었다. ORSV에 감염된 세포내 엽록체는 불규칙적인 모습을 보였다. 미토콘드리아, 핵, 액포, 소포 및 기타 세포내 소기관들내에서는 바이러스 입자를 볼 수 없었다. 원형질연락사(plasmodesmata)는 다소 확장되고, 바이러스 입자들이 이들 원형질연락사 주변에 존재하였다.