• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.06a
• /
• pp.347-347
• /
• 2008

본 연구에서는 별도의 소결과정 없이 상온에서 치밀한 복합체 후막의 제조가 가능한 Aerosol Deposition Method (ADM)를 이용하여 SOP를 실현시키기 위한 기판 재료로서 알루미나 기반의 알루미나-폴리이미드 복합체를 제조하고 그 특성에 대한 평가를 진행하였다. SEM 관찰결과 기공이 거의 없고 치밀한 구조의 복합체가 상온에서 성공적으로 형성되었음이 확인되었다. XRD 와 FT-IR 분석 결과 알루미나와 폴리이미드 모두가 복합체에 존재함을 확인할 수 있었다. 또한 XRD 분석결과 출발 원료에 폴리이미드 함량이 증가할수록 ADM으로 제조된 복합체 내부의 알루미나의 결정자 크기가 증가하는 결과를 보였다. 복합체의 알루미나 충진율을 확인하기 위한 간접적인 방법으로 복합체 후막을 연마하여 복합체 내부를 노출시킨 후 폴리이미드의 용매인 Methyl Ethyl Ketone으로 폴리이미드를 식각시켜 남아있는 알루미나 영역을 관찰한 SEM 분석결과 알루미나가 60% 이상 복합체의 대부분을 이루고 있다는 사실을 관찰할 수 있었다. 복합체의 미세구조를 확인하기 위하여 TEM 분석결과 기존에 보고된 ADM으로 제조된 알루미나 후막의 결정자 크기인 10~20 nm 보다 큰 100 nm 범위의 결정자 크기를 관찰 할 수 있었다. 유전특성평가 결과 유전율과 tan$\delta$는 1 MHz에서 각각 9.0, 0.0072로서 알루미나만을 원료로 성막시킨 후막의 유전 특성을 크게 떨어뜨리지 않으며 알루미나 후막과 유사한 결과를 보였다. 추후 복합체의 균일성 향상 및 고주파 영역의 유전 특성 향상을 통하여 세라믹의 취성 및 가공성이 개선된 3 차원 적층 기판재료로의 응용이 기대될 것으로 전망된다.

• Korean Journal of Plant Taxonomy
• /
• v.47 no.3
• /
• pp.222-235
• /
• 2017

A comparative study of the leaf epidermal micromorphology in the tribe Neillieae (Neillia: 4 species, 4 varieties; Physocarpus: 5 species; Stephanandra: 2 species) was carried out using scanning electron microscopy in order to evaluate the taxonomic and systematic implications of these characteristics. The leaves of the genera Neillia and Stephanandra were hypostomatic, whereas those of P. monogynus, P. opulifolius were amphistomatic. The range of the size of the stomata is $12.02-34.39{\times}10.76-27.13{\mu}m$; the smallest was found in N. thyrsiflora (average $13.98{\times}12.43{\mu}m$; $L{\times}W$), while the largest was measured in N. gracilis (average $26.82{\times}20.67{\mu}m$; $L{\times}W$). Paracytic stomata complexes are only found in N. affinis, and the anomocytic type was most commonly found. The papillate epidermal cell type was only observed on the abaxial surfaces of P. insularis. Platelet epicuticular waxes were found on the adaxial surfaces of N. affinis and S. tanakae. Four types (unicellular non-glandular, two- to five-armed, stellate, and glandular) of trichomes were found on the leaves. Stellates were observed in all species of Physocarpus except for P. insularis. Consequently, leaf epidermal micromorphological characteristics (e.g., the presence of papillate epidermal cells and stellate, and stomata complexes) may have high taxonomic and systematic value in Neillieae. Our results strongly support previous molecular phylogenetic and palynological hypotheses that Stephanandra and Neillia are a single genus and that Physocarpus insularis should be considered as a member of Spiraea.

• Clean Technology
• /
• v.22 no.4
• /
• pp.308-315
• /
• 2016

$SiO_x/ZnO$ composites were prepared from sol-gel method for excellent cycle life characteristics. The composites were coated by PVC as a carbon precursor. ZnO removal to create a void space therein was able to buffer the volume change during charge and discharge. To determine the crystal structure and the shape of the synthesized composite, XRD, SEM, TEM analysis was performed. The carbon contents in the composites were confirmed by TGA. The pore structure and pore size distribution of the composite was measured with the BET specific surface area analysis and BJH pore size distribution. Enhanced electric conductivity by carbon addition was determined from powder resistance measurement. Electrochemical properties were measured with the AC impedance and the charge and discharge cycle life characteristics. When carbon was coated on the $SiO_x/ZnO$ sample, the electrical conductivity and the discharge capacity were increased. After removal of ZnO with HCl the surface area of the sample was increased, but the discharge capacity was decreased. $SiO_x/ZnO$ sample without acarbon coating showed very low discharge capacity, and after carbon coating the sample showed high discharge capacity. For cycle life characteristics, $C-SiO_x/ZnO$ composite (Zn : Si : C = 1 : 1 : 8) with a capacity of $815mAh\;g^{-1}$ at 50 cycle and 0.2 C has higher capacity than existing graphite-based anode materials.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.11a
• /
• pp.224-224
• /
• 2008

고주파용 집적회로 기판소재로의 응용을 위해 세라믹 특유의 취성을 개선한 $Al_2O_3$-polyimide 복합체 후막을 에어로졸데포지션법을 이용해 제조하고 그 특성을 평가하였다. 그 결과 기공이 거의 없이 치밀한 구조를 갖는 $Al_2O_3$-polyimide 복합체 후막이 구리 및 유리 기판 상에 성막 되었음이 SEM 및 EDS을 통해 확인되었다. 상용 $Al_2O_3$ 출발 파우더를 사용한 복합체 제조시 1 MHz에서 유전율은 6.7, 유전 손실률은 0.026 이었다. 유전특성의 향상을 위하여 에어로졸데포지션법으로 성막된 $Al_2O_3$-polyimide 복합체 후막의 후속 열처리 결과 유전손실율이 0.026에서 0.007로 감소하였다. 또한 집적회로 기판소재로의 응용을 위한 저온화 제조공정 확립을 위하여 $Al_2O_3$ 출발 파우더의 공정 전 열처리 후 상온에서 성막한 경우에도 어떠한 후속 열처리 없이 유전손실률이 0.007로 감소하였다.

• Proceedings of the Korean Ceranic Society Conference
• /
• 2003.10a
• /
• pp.156.2-156
• /
• 2003

• Journal of the Korean Ceramic Society
• /
• v.33 no.12
• /
• pp.1365-1372
• /
• 1996

In order to obtain a transparent and dimer-free Ormosil embedded with orgainc dye variations of gel struc-ture and optical properties were studied as a functiion of the change of gel composition. The Ormosils which have good optical property were produced in the 90/10 ratio of TEOS/PDMS and the structural variations of the gel were achived by the change of ratio of HCl/TEOS. As the ratio of HCl/TEOS was increased pore size of the Ormosil enlarged and porosity increased. Increasing HCl concentration led to gradually lower trans-mittance values. In the xerogel doped with the organic dye Rhodamine 6G perchlorate a dimer peak near 500nm was observed with the increase of the ratio of HCl/TEOS

• Korean Chemical Engineering Research
• /
• v.53 no.3
• /
• pp.357-363
• /
• 2015

The development of the environment-friendly tire that meets the standard requirements according to tire labeling system can be improved through using highly homogeneous silica immobilized zinc oxide nanoparticles. In this study, a considerable amount of nanoporous silica was essentially added into nano zinc oxide to improve the physiochemical properties of the formed composite. The introduction of nanoporous silica materials in the composite facilitates the improvement of the wear-resistance and increases the elasticity of the tread. Therefore, the introduction of nanoporous silica can replace carbon black as filler in the formation of composites with desirable properties for conventional green tire. Herein, mesoporous silica immobilized zinc oxide nanoparticle with desirable properties for rubber compounds was investigated. Composites with homogeneous dispersion were obtained in the absence of dispersants. The dispersion stability was controlled through varying the molar ratio, ageing time and mixing order of the reactants. A superior dispersion was achieved in the sample obtained using 0.03 mol of zinc precursor as it had the smallest grain size (50.5 nm) and then immobilized in silica aged for 10 days. Moreover, the specific surface area of this sample was the highest ($649m^2/g$).

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.25 no.5
• /
• pp.157-164
• /
• 2021

Recently, a number of studies have been conducted on photocatalysts and adsorbents that can remove harmful substances to improve environmental problems related to fine particles. In this study, a porous foam composites were fabricated using palm-based activated carbon having a large amount of micro-pores and foam concrete with a significantly larger total pore volume compared to general construction materials. To evaluate the adsorption potential of fine particles, the pore structure of the foam composites were analyzed. For the analysis of the pore structure of the foam composite, BET and Harkins-jura theory were applied from the measured nitrogen adsorption isotherm. From the results of the analysis, the specific surface area and micro-pore volume of the foam composite containing activated carbon increased significantly compared to Plain. As thereplacement of activated carbon increased, the specific surface area and micro-pore volume of the foam composite tended to increase. It seems that the foam composite has high adsorption performance for gaseous fine particle precursor such as nitrogen oxides.

• Korean Journal of Plant Taxonomy
• /
• v.46 no.2
• /
• pp.199-212
• /
• 2016

A comparative study of leaf epidermal microstructures in the tribe Sorbarieae (Adenostoma: 3 spp., Chamaebatiaria: 1 sp., Sorbaria: 11 spp., Spiraeanthus: 1 sp.) including related genera Gillenia (2 spp.) and Lyonothamnus (2 spp.) was carried out using scanning electron microscopy (SEM) in order to evaluate their significance in taxonomy. The leaves of Adenostoma, Chamaebatiaria, and Spiraeanthus were amphistomatic, whereas Gillenia, Lyonothamnus, and Sorbaria were hypostomatic. The size range of the guard cells is $7.84-48.7{\times}5.86-38.6{\mu}m$; the smallest one was found in Sorbaria tomentosa var. tomentosa ($7.84-11.8{\times}6.84-10.5{\mu}m$), while the largest measured example was Adenostoma fasciculatum var. obtusifolium ($30.3-48.7{\times}18.8-38.6{\mu}m$). Anomocytic stomata complex were the most frequent type (rarely cyclocytic), with usually both anomocytic and actinocytic types occurring in one leaf. On the surfaces, both the adaxial and abaxial anticlinal walls of the subsidiary cells vary (e.g., straight/curved, undulate, sinuate). Four types (unicellular non-glandular trichome, stellate, glandular trichome, pustular glandular trichome) of trichomes are found in the leaves. The epicuticular wax can be divided two types: membraneous platelets (Lyonothamnus) and platelets (Sorbaria arborea var. arborea, S. arborea var. subtomentosa, S. kirilowii, S. tomentosa var. tomentosa, Spiraeanthus schrenkianus). The trichome diversity (in particular, stellate, gland) and the existence of epicuticular wax may have taxonomic significance, although the leaf epidermal micromorphological characteristics do not provide synapomorphy in this tribe. These leaf micromorphological features are most likely better understood in the Sorbarieae when used in conjunction with external morphological characters.

• Korean Journal of Plant Taxonomy
• /
• v.31 no.3
• /
• pp.267-282
• /
• 2001

To examine the leaf epidermal microstructure of three genera (Scopolia s.s., Anisodus, AtroPanthe, including Przewalskia as an outgroup) in the genera Scopolia Jacq. s.l., leaves of 10 species (37 specimens) were investigated by the light microscopy (LM) and scanning electron microscopy (SEM). The stomata of studied taxa were 'amphistomatic type' and the size (guard cell) range was $18-64{\times}11-48{\mu}m$. The size of stomata is slightly differed from between the taxa; the smallest size of stomata were found in the monotypic genus, Przewalskia ($24-27{\times}16-17{\mu}m$), on the other hand the largest one was found in Anisodus carniolicoides ($62-64{\times}43-48{\mu}m$). The stomatal complex was mostly anomocytic (in Scopolia s.s., Anisodus taxa : A. luridus, A. carniolicoides, A. acutangulus) and sometimes anisocytic (in Anisodus tanguticus, Przewalskia, Atropanthe). The stomata is mostly crescent in shape, but rarely circular, especially in Przewalskia tangutica. The shapes of epidermal cells are similar in both adaxial and abaxial sides, and mostly undulate/sinuate polygonal anticlinal wall, but rarely arched in Przewalskia tangutica. The epicuticular wax was not well developed in most studied taxa, except Anisodus tanguticus which is well developed cuticular striae around the stomatal complex. The elongate-headed glandular trichomes were found in Scopolia s.s. and Przewalskia. While the taxa of Anisodus and Atropanthe have not any trichomes (i. e., glabrous), except Anisodus luridus, which has simple or sometimes branched (dendritic- type) non-glandular trichome. Finally, the systematic and ecological significance of the leaf micromorphological features (stomata complex, trichome, etc.) in identification and elucidation of Scopolia s.l. including Przewalskia, especially between or within the genera including among the species is also discussed.