• 한국표면공학회지
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• 제46권6호
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• pp.248-257
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• 2013

It is generally recognized that thin Pd-Cu alloy films fabricated by sputtering show a wide range of microstructures and properties, both of which are highly dependent on the sputtering conditions. In view of this, the present study aims to investigate the relationship between the performance of hydrogen separation membranes and the microstructure of Pd alloy films depending on sputtering deposition conditions such as substrate temperature, working pressure, and DC power. We fabricated thin and dense Pd-Cu alloy membranes by the micro-polishing of porous Ni support, an advanced Pd-Cu sputtered multi-deposition under the conditions of high substrate temperature / low working pressure / high DC power, and a followed by Cu-reflow heat-treatment. The result of a hydrogen permeation test indicated that the selectivity for $H_2/N_2$ was infinite because of the void-free and dense surface of the Pd alloy membranes, and the hydrogen permeability was 10.5 $ml{\cdot}cm^{-2}{\cdot}min^{-1}{\cdot}atm^{-1}$ for a 6 ${\mu}m$ membrane thickness.

• Journal of Periodontal and Implant Science
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• 제28권2호
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• pp.263-273
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• 1998

For histologic observation of the regenerated bone following guided tissue regeneration (GTR) using ePTFE membranes with calcium carbonate implant and autogenous bone graft, biopsies were collected from 2 patients during 5-year-postoperative surgical reentry. In both combined cases with guided tissue regeneration in conjunction with calcium carbonate implant and autogenous bone graft, significant bone fill and gain in probing attachment level was observed. In histologic examination, specimen in GTR case with calcium carbonate grafting was composed of a dense bone containing vascular channel with lamellar structure and viable bone cells in lacunae, however considerable calcium carbonate particles remained unresorbed and isolated from regenerated bone by the dense cellular and fibrous connective tissue. No formative cells could be seen in contact with remained calcium carbonate particles. In GTR case with autogenous bone grafting, specimen show was composed of a dense lamellar bone containing vascular channel, which showed normal alveolar bone architectures. The present observation indicate that guided tissue regeneration in conjunction with grafting, especially autogenous bone graft, has highly osteogenic potential, however resorbable calcium carbonate granules were not completely resorbed at 5 year postimplantation.

• 대한화장품학회지
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• 제39권1호
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• pp.47-54
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• 2013

알로에 겔이 분산된 W/O 에멀젼을 감압 건조하는 방법으로 분산상의 수분을 제거하여 알로에 겔 마이크로캡슐을 제조하였다. 마이크로캡슐은 미네랄오일로 세척하고 재현탁시켜 유화제를 제거한 후에도 안정적인 현탁액으로 유지되었으며, 내부가 균일하게 채워진 직경 6.6 ${\mu}m$ 이하인 구형 입자로 구성되어 있었다. 미네랄오일에 재현탁된 마이크로캡슐은 분율이 41% 이상에서 급격하게 점도가 증가하였고, 300 Pa 이상의 항복응력을 가진 전단유동화 특성을 나타내었으나, 틱소트로피는 뚜렷하게 관찰되지 않는 유변학적인 특성을 보였다. 오일에 현탁된 알로에 겔 마이크로캡슐의 분율이 높을수록 반고체의 특성이 증가하고 $105^{\circ}C$에서 15 min 동안 가열하여도 에멀젼의 안정성이 유지됨을 경시적으로 관찰하였다. 따라서 알로에 겔 마이크로캡슐 현탁 크림을 기본 제형으로 다양한 종류의 알로에 겔 화장품의 개발이 가능할 것으로 예상된다.

• 한국차세대컴퓨팅학회논문지
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• 제14권6호
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• pp.66-74
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• 2018

최근 가상환경에서 몰입감을 늘리고 자유로운 상호작용을 제공하기 위한 손 제스처 인식에 대한 연구가 활발히 진행되고 있다. 그러나 기존의 연구는 특화된 센서나 장비를 요구하거나, 낮은 인식률을 보이고 있다. 본 논문은 정적 손 제스처와 동적 손 제스처 인식을 위해 카메라 이외의 별도의 센서나 장비 없이 딥러닝 기술을 사용한 손 제스처 인식 방법을 제안한다. 일련의 손 제스처 영상을 고주파 영상으로 변환한 후 손 제스처 RGB 영상들과 이에 대한 고주파 영상들 각각에 대해 덴스넷 3차원 합성곱 신경망을 통해 학습한다. 6개의 정적 손 제스처와 9개의 동적 손 제스처 인터페이스에 대해 실험한 결과 기존 덴스넷에 비해 4.6%의 성능이 향상된 평균 92.6%의 인식률을 보였다. 본 연구결과를 검증하기 위하여 3D 디펜스 게임을 구현한 결과 평균 34ms로 제스처 인식이 가능하여 가상현실 응용의 실시간 사용자 인터페이스로 사용가능함을 알 수 있었다.

• 한국지진공학회논문집
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• 제5권4호
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• pp.9-16
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• 2001

본 연구의 목적은 지진에 의한 비보강 조적조의 거동을 평가하는 것이다. 효율적인 평가를 위하여 유사동적해석법을 사용하였다. 저층의 비보강 조적조에 대하여 지진하중에 의한 지반-구조물의 상호작용에 따른 영향을 평가하기 위하여 단단한 지반에 놓여진 구조물과 연약한 지반에 좋여진 구조물을 비교하였다. 그 결과 연약한 지반위에 놓인 구조물의 층 전단력과 밑면 전단력이 상대적으로 증가하는 것으로 나타났다. 또한 현재 사용되고 있는 내진기준에 주어진 약산식에 따라 해석을 수행할 경우 연약한 지반에 놓인 건물이 경우 전단력을 과소평가 할 수 있는 것으로 나타났다.

• E2M - 전기 전자와 첨단 소재
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• 제10권10호
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• pp.983-988
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• 1997

We investigated the structural and dielectric properties of PZT(20/80)/PZT(80/20) heterolayered thin films that fabricated by the alkoxide-based Sol-Gel method. PZT(20/80)/PZT(80/20) heterolayered thin films were spin-coated on the Pt/Ti/SiO$_2$/Si substrate with PZT(20/80) film of tetragonal structure and PZT(80/20) film of rhombohedral structure by turns. Each layers were dried to remove the organic materials at 30$0^{\circ}C$ for 30min and sintered at $650^{\circ}C$ for 1hr. This procedure was repeated several times to form PZT(20/80)/PZT(80/20) heterolayered films and thickness of the film obtained by one-times of drying/sintering process was approximately 80-90nm. PZt-1, 3, 5 films with top layer of PZT(20/80) film of tetragonal structure showed fine grain structure and PZT-2, 4, 6 films with top layer of PZT(80/20) film of rhombohedral structure showed the dense grain microstructure without rosette-type. Dielectric constant and dielectric loss of the PZT-6 film were approximaterly 1385 and 3.3% respectively. Increasing the number of coatings remanent polarization was increased and coercive field was decreased and the values of the PZT-6 film were 8.13$\mu$C/cm$^2$and 12.5kV/cm respectively.

• 한국재료학회지
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• 제31권12호
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• pp.697-703
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• 2021

Aluminum nitride having a dense hexagonal structure is used as a high-temperature material because of its excellent heat resistance and high mechanical strength; its excellent piezoelectric properties are also attracting attention. The structure and residual stress of AlN thin films formed on glass substrate using TFT sputtering system are examined by XRD. The deposition conditions are nitrogen gas pressures of 1 × 10^-2, 6 × 10^-3, and 3 × 10^-3, substrate temperature of 523 K, and sputtering time of 120 min. The structure of the AlN thin film is columnar, having a c-axis, i.e., a <00·1> orientation, which is the normal direction of the glass substrate. An X-ray stress measurement method for crystalline thin films with orientation properties such as columnar structure is proposed and applied to the residual stress measurement of AlN thin films with orientation <00·1>. Strength of diffraction lines other than 00·2 diffraction is very weak. As a result of stress measurement using AlN powder sample as a comparative standard sample, tensile residual stress is obtained when the nitrogen gas pressure is low, but the gas pressure increases as the residual stress is shifts toward compression. At low gas pressure, the unit cell expands due to the incorporation of excess nitrogen atoms.

• Applied Microscopy
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• 제52권
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• pp.6.1-6.5
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• 2022

We examined the morphology of the fertilized egg and the fine structure of fertilized egg envelopes of Poropanchax normani belonging to the family Poeciliidae, also known as Norman's lampeye using light and electron microscopes. The fertilized eggs with narrow perivitelline space were found to be spherical and demersal, additionally containing small oil droplets in the vitelline membrane. Further, a bundle of adhesive filaments was observed to be present on one side of the fertilized egg. These filaments possessed remarkably high elasticity and were approximately 1-3mm in length. The size of the fertilized egg was determined to be about 1.49 ± 0.07mm (n=30). The outer surface appeared smooth, and adhesive filaments originating at different location of the surface of the envelope were found to be distributed around the egg envelope and were joined together to form a single long bundle in scanning electron microscopic observation. A peak-like structure formed of several straight wrinkles was observed around the micropyle. However, the complete structure of the micropyle could not be studied due to the depth at which it was located. Additionally, the total thickness of the egg envelope was ascertained to be approximately12.5-14.5㎛. The egg envelope consisted of two distinct layers, an outer electron dense layer and an inner lamellar layer, further consisting of 10 sublayers of varying thicknesses. Collectively, it was observed that the morphological characteristics of the fertilized egg, fine structures surrounding the micropyle, outer surface, adhesive structure consisting adhesive filaments, and sections of fertilized egg envelope displayed species specificity.

• Advanced Composite Materials
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• 제18권1호
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• pp.61-75
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• 2009

The effect of porous matrix on thermal fatigue behavior of 3D-orthogonally woven SiC/SiC composite was evaluated in comparison with that having relatively dense matrix. The porous matrix yields open air passages through its thickness which can be utilized for transpiration cooling. On the other hand, the latter matrix is so dense that the air passages are sealed. A quantity of the matrix was varied by changing the number of repetition cycles of the polymer impregnation pyrolysis (PIP). Strength degradation of composites under thermal cycling conditions was evaluated by the $1200^{\circ}C$/RT thermal cycles with a combination of burner heating and air cooling for 200 cycles. It was found that the SiC/SiC composite with the porous matrix revealed little degradation in strength during the thermal cycles, while the other sample showed a 25% decrease in strength. Finally it was demonstrated that the porous structure in 3D-SiC/SiC composite improved the thermal fatigue durability.

• Applied Microscopy
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• 제13권1호
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• pp.49-61
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• 1983

Protoplast releasing mechanisms from Trichoderma koningii, fine structures of the released protoplsts, and their regeneration mode were studied by scanning and transmission electron microscopy. Two types of protoplast releasing mechanisms were observed. In one mechanism, cytoplasm emerged through a cell wall pore developed by cell lytic enzymes and formed a spherical protoplast. In the other mechanism, as the cell wall became progressively thinner, the inner cytoplasm partially rounded to form nonspherical bodies which became spherical protoplasts after being released into the enzyme solution. But, these two types of protoplast releasing mechanisms did not seem to be. mutually exclusive but could occur on the same mycelium simultaneously. And it appeared that cytoplasm which did not become a protoplast by the first mechanism could from a protoplast by the second mechanism. The preparations contained two types of protoplasts, released from different sites of the mycelia. Those released from younger mycelia had dense cytoplasm and small vesicles. Those released from the older mycelia had less dense cytoplasm and larger vacuoles. In the case of regeneration, before producing normal mycelia, most of the protoplasts assumed aberrant tube and yeast-like-forms. Normal mycelia were produced at the end of the yeastlike-forms and sometimes in the middle of the aberrant tube.