• Analytical Science and Technology
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• v.13 no.6
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• pp.705-711
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• 2000

We have studied the structural characterization, surface morphology and electrical properties for boron dopped polyacene anode material from phenolic resin for lithium secondary battery. The boron dopped anode material were characterized as boron contents of 5, 10, 15 and 20%, respectively. From the X-ray results, the all kinds of compounds were observed for the diffraction patterns for typical amorphous carbons. The SEM morphology showed formation of semi spherical granule for the boron dopped compounds. As the result of the electrical charge/discharge and impedance data, the 10 and 15% boron dopped materials showed good properties on the ions and electron transfer effect of battery.

• Polymer(Korea)
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• v.29 no.5
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• pp.445-450
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• 2005

Hyaluronic acid-based beads were prepared in order to develop a biomedical material for augumentation. Hyaluronic acid was crosslinked by 1,3-butadiene diepoxide in a suspension state maintained by rapid mixing of soybeen oil and hyaluronic acid solution. The particle size, surface area and swelling ratio were measured to investigate the physical properties of the synthesized beads and the bead surface was examined by scanning electron microscopy. The beads were formed in the range of $5-12vol\%$ concentration of crosslinking agent, which showed monodisperse size distribution. Both BET surface area and swelling ratio decreased as the concentration of either hyaluronic acid or crosslinking agent increased, and crosslinking temperature decreased. Bead size could be effectively controlled by mixing speed without affecting other physical property.

• Journal of the Korean Ceramic Society
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• v.41 no.1
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• pp.36-40
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• 2004

$SnO_2$ thin films were deposited on a $SiO_2$/Si substrate with the flow of Ar and $O_2$ of 25 sccm by RF-magnetron sputtering method. the post-annealing was conducted at $500^{\circ}C$ in atmosphere of dry air and $N_2$ were changed fairly, while those annealed in dry air resembled as-deposited films. This may be attributed to the desorption of adsorbed oxygen and the extraction of lattice oxygen during annealing. Resistivity of films annealed in $N_2$ was increased over 5 times than that of as-deposited films. It can be explained that the increment of resistivity may result from the discontinuous conduction path with change of microstructures after annealing in $N_2$.

• Journal of KSNVE
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• v.9 no.3
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• pp.621-628
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• 1999

The fundamental dynamic properties of the planar electric charged particle are investigated experimentally. The experiment is conducted using electric charged spheres(4 table tennis balls with conductive surfaces) suspended by insulating strings to cancel the gravitational force. The measurements of the equilibrium angles and the natural frequencies of oscillation agree well with the analytical predictions with some error, respectively.

• Journal of the Korean institute of surface engineering
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• v.16 no.4
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• pp.160-172
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• 1983

티오요소류, 폴리에테르류, 염료와 같은 유기화합물이 첨가된 황산동 전기도금욕에서 석출된 구리의 광택, 평활력효과를 무첨가욕과 기존 광택제가 첨가된 도금욕에서와 각각 비교하여 이들 유기첨가제가 구리의 석출상태와 음극분극에 미치는 영향을 Hull cell 실험과 현미경관찰, 전기화학적 측정방법에 의해 고찰하였다. 황산동 전기도금욕에서 thiourea, 2-mercapto-2-imidazoline, 1-acetyl-2-thiourea와 같은 유기 황화합물은 비교적 고전류 밀도 범위에서 결정성장이 억제되고 입자가 미세한 구리석출을 일으켜 양호한 광택효과와 평활력을 가져오나, 특히 저전류밀도에서는 해로운 줄무늬가 발생한다는 점에서 많은 개선의 여지가 필요하다. 그러나 이들 유기 황화합물에 1,3-dioxolane polymer와 소량의 염소 이온을 혼합 첨가할 것 같으며 넓은 전류밀도 범위에서 양호한 광택과 평활력이 있는 동석출을 얻을 수 있었다.

• Tuberculosis and Respiratory Diseases
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• v.43 no.2
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• pp.210-220
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• 1996

Background : Neutrophils or monocytes separated in vitro by the adherence to plastic surface are known to be activated by surface adherence itself and subsequent experimental data might be altered by surface adherence. In the process of surface adherence, adhesion molecules have a clear role in intracellular signal pathway of cellular activation. Human alveolar macrophages(HAM) are frequently purified by the adherence procedure after bronchoalveolar lavage. But the experimental data of many reports about alveolar macrophages have ignored the possibility of adhesion-induced cellular activation. Method : Bronchoalveolar lavage was performed in the person whose lung of either side was confirmed to be normal by chest CT. With the measurement of hydrogen peroxide release from adherent HAM to plastic surface and non-adherent HAM with or without additional stimulation of phorbol myristate acetate(PMA) or N-formyl-methionyl-leucyl-phenylalanine (fMLP), we observed the effect of the adherence to plastic surface. We also evaluated the effect of various biological surfaces on adhesion-induced activation of HAM. Then, to define the intracellular pathway of signal transduction, pretreatment with cycloheximide, pertussis toxin and anti-CD11/CD18 monoclonal antibody was done and we measured hydrogen peroxide in the culture supernatant of HAM. Results : 1) The adherence itself to plastic surface directly stimulated hydrogen peroxide release from human alveolar macrophages and chemical stimuli such as phorbol myristate acetate(PMA) or N-formyl-methionyl-leucyl-phenylalanine(fMLP) colud not increase hydrogen peroxide release in these adherent macrophages which is already activated. 2) PMA activated human alveolar macrophages irrespective of the state of adhesion. However, fMLP stimulated the release of hydrogen peroxide from the adherent macrophages, but not from the non-adherent macrophages. 3) HAM adherent to A549 cell(type II alveolar epithelium-like human cell line) monolayer released more hydrogen peroxide in response to both PMA and fMLP. This adherence-dependent effect of fMLP was blocked by pretreatment of macrophages with cycloheximide, pertussis toxin and anti-CD18 monoclonal antibody, Conclusion : These results suggest that the stimulatory effect of PMA and fMLP can not be found in adherent macrophage because of the activation of human alveolar macrophage by the adherence to plastic surface and the cells adhered to biologic surface such as alveolar epithelial cells are appropriately responsive to these stimuli. It is also likely that the effect of fMLP on the adherent macrophage requires new protein synthesis via G protein pathway and is dependent on the adhesion between alveolar macrophages and alveolar epithelial cells by virtue of CD11/CD18 adhesion molecules.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.2
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• pp.33-37
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• 2014

We have developed a novel passivation process employing a sacrificial gallium oxide process in order to recover the surface damage in AlGaN/GaN HFETs. Even with a conventional prepassivation process, surface damage during high temperature ohmic annealing cannot be avoided completely. Therefore, it is necessary to recover the damaged surface to avoid the characteristic degradation. In this work, a sacrificial gallium oxide process has been proposed in which the damaged surface after ohmic annealing was oxidized by oxygen plasma treatment and thereafter etched back using HCl. As a result, the leakage current was dramatically reduced and thus the subthreshold slope was significantly improved. In addition, the maximum drain current level was increased from 594 to 634 mA/mm. To verify the effects, the surface conditions were carefully investigated using X-ray photoelectron spectroscopy.

• Journal of the Society of Naval Architects of Korea
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• v.31 no.2
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• pp.45-56
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• 1994

A computationally efficient numerical method based on potential flow is developed for time-domain simulation of the nonlinear free-surface flows around a 2-dimensional hydrofoil. This numerical method, namely, spectral/boundary-element method, is a mixed one of the high-order spectral method and the boundary-element method in time-domain. The high-order spectral method is used to calculate the nonlinear evolution of free-surface, and the boundary-element method is used to calculate the effects of the hydrofoil and the shed vortex. As application examples, nonlinear free-surface flows around a 2-dimensional hydrofoil which starts from the rest and translates near the free-surface with or without harmonic oscillations are calculated. Nonlinear/unsteady results of free-surface waves and hydrodynamic farces are shown and discussed. Particularly, the results of steady-state which are obtained as a special case of the present unsteady solution are compared with others' calculated and experimental results, and good agreements are observed.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.118-118
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• 1999

CVD방법에 의한 TiN 박막 형성에 있어서 ICP-CVD 방법이 대두되고 있다. 이것은 precursor에 대한 radical 형성, 식각된 패턴에서 양 벽의 self-shadowing 효과, 낮은 tress등으로 dense 한 박막을 얻을 수 있기 때문이다. TiN 박막은 Si 기판의 온도를 상온에서 50$0^{\circ}C$까지 유지하면서 TEMAT의 유량을 5-20sccm으로 변화시키면서 증착하였다. 증착 후 TiN 박막의 결정화에 따른 열처리는 Ar과 N2-가스분위기에서 in-situ로 증착하였다. 증착 후 TiN 박막증착 조건수립에 따른 플라즈마 특성진단은 전자의 온도와 밀도, 평균 전자밀도, 이온 에너지 분포, radical 분포, negative 이온분포 등으로 측정하였다. 플라즈마 변수에 따른 TiN 박막의 결정성과 상 변화는 XRD로 분석하였고, 조성비 및 TiN 박막의 원소화학적 상태, 결합에너지, 각 상에 따른 결합 에너지 천이정도, 초기 형성과정 및 반응기구 등은 RBS와 XPS로 조사하였다. TiN 박막의 표면상태, morphology 거칠기, TiN/Si(100)구조에서 계면상태 등은 SEM, AFM, 그리고 HRTEM으로 분석하였다. TiN 구조 박막의 비저항, carrier concentration 그리고 mobility 측정은 박막의 표면이 균일하고 bls-홀이 없는 것으로 하여 4-point probe 방법으로 측정하였다. 이들 분석으로부터 ICP-CVD 방법에 의하여 형성된 TiN 박막이 초고집적 반도체 소자의 contact barrier layer로서의 적용 가능성을 평가하였다.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2001.04a
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• pp.158-158
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• 2001

산업용 포장재의 주원료로서 이용되고 있는 국산골판지고지(KOCC)는 반복적인 재활용 으로 인하여 섬유장이 짧고 매우 각질화된 상태이며, 펄프 내 미세분 함량이 50%이상에 달 하고 있다. 또한 섬유의 표면이 인쇄잉크, stickies 및 각종 이물질로 오염됨에 따라, 섬유자 체가 보유하고 있는 섬유간 결합 능력이 저하된 상태이다. 국산 골판지 고지를 재활용한 골판지 원지의 생산 시 탈수성 및 강도 저하의 단점을 극 복하는 것은 생산성과 품질향상의 측면이외에 고지 재생을 촉진시킨다는 의미를 지니고 있다. 상기한 KOCC의 단점을 극복하는 방안으로 섬유분과 미세분의 적절한 분급을 통하여 초지 시 탈수저향을 감소시키고 더불어 종이의 강도를 개선하는 방안이 본 연구센터에 의해 고안되었다. 아울러 고온압착건조 처리를 활용한 종이의 물성 개선법이 국내에 이미 적용된 상태로 건조시간의 단축 및 종이의 제반물성을 개선시켜주게 되었다. 하지만 이미 열화된 KOCC에 고온압착건조 처리를 적용하여 밀도를 증가시킨다 할지라 도 천연의 UKP를 이용한 종이에 준 하는 강도를 얻는 데에 한계가 있었다. K KOCC 펄프의 섬유간 결합 능력을 개선시키기 위하여 본 연구에서는 Kneading처리와 지력증강제를 첨가를 함께 실시하는 방안을 검토하였으며, 고온압착건조된 골판지 원지의 표면에 코팅처리를 실시하여 그 효과를 분석하였다. 이를 통해 국산 골판지고지를 재활용한 골판지원지의 강도 극대화 방안을 탐색하고자 하였다.