• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1996년도 춘계학술대회논문집; 부산수산대학교, 10 May 1996
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• pp.130-135
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• 1996

This paper presents a proof-concept investigation on the active vibration control of two hybrid smart structures (HSSs). The first one is consisting of a piezoelectric film (PF) actuator and an electro-rheological fluid(ERF) actuator, and the other is featured by a piezoceramic (PZT) actuator and a shape memory alloy (SMA) actuator. For the PF/ERF hybrid smart structure, both the increment of the damping ratios and the suppression of the tip deflections are evaluated in order to demonstrate control effectiveness of the PF actuator and ERF actuator and the hybrid actuation. For the PZT/SMA hybrid smart structure, the PZT actuator takes account of the high frequency excitation, while the SMA actuator exerts large vibration control force. The experimental results exhibit superior abilities of the hybrid actuation systems to tailor elastodynamic responses of the HSS rather than a single class of actuation system alone.

• ETRI Journal
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• 제33권1호
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• pp.13-17
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• 2011

A highly miniaturized on-chip $180^{\circ}$ hybrid employing periodic ground strip structure (PGSS) was realized on a silicon radio frequency integrated circuit. The PGSS was placed at the interface between $SiO_2$ film and silicon substrate, and it was electrically connected to top-side ground planes through the contacts. Owing to the short wavelength characteristic of the transmission line employing the PGSS, the on-chip $180^{\circ}$ hybrid was highly miniaturized. Concretely, the on-chip $180^{\circ}$ hybrid exhibited good radio frequency performances from 37 GHz to 55 GHz, and it was 0.325 $mm^2$, which is 19.3% of a conventional $180^{\circ}$ hybrid. The miniaturization technique proposed in this work can be also used in other fields including compound semiconducting devices, such as high electron mobility transistors, diamond field effect transistors, and light emitting diodes.

• Macromolecular Research
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• 제10권4호
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• pp.194-203
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• 2002

In resin infusion process(RIP), the fiber and the resin are in contact with each other for an impregnation step and often results in flow-induced defects such as poor fiber wetting and void formation. Resin flow characteristics in transverse direction and process modeling for woven fabric were studied, and the process modeling was applied to the manufacturing of hybrid composite materials. This study also considered the compressibility of woven fabrics in a series of compression force, and it was fitted well to an elastic model equation. Void formation was varied with the processing conditions in the stage of manufacturing composites using RIP. It was concluded from this study that proper combination of pressure build-up and dynamic heating condition makes important factor for flow-induced composite processing.

• International Journal of Fluid Machinery and Systems
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• 제3권2호
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• pp.150-159
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• 2010

Laidback fan shaped film-cooling hole is formulated numerically and optimized with the help of three-dimensional numerical analysis, surrogate methods, and the multi-objective evolutionary algorithm. As Pareto optimal front produces a set of optimal solutions, the trends of objective functions with design variables are predicted by hybrid multi-objective evolutionary algorithm. The problem is defined by four geometric design variables, the injection angle of the hole, the lateral expansion angle of the diffuser, the forward expansion angle of the hole, and the ratio of the length to the diameter of the hole, to maximize the film-cooling effectiveness compromising with the aerodynamic loss. The objective function values are numerically evaluated through Reynolds- averaged Navier-Stokes analysis at the designs that are selected through the Latin hypercube sampling method. Using these numerical simulation results, the Response Surface Approximation model are constructed for each objective function and a hybrid multi-objective evolutionary algorithm is applied to obtain the Pareto optimal front. The clustered points from Pareto optimal front were evaluated by flow analysis. These designs give enhanced objective function values in comparison with the experimental designs.

• 한국해양공학회지
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• 제23권3호
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• pp.35-39
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• 2009

The main objective of this study was to investigate fiber reinforced composite materials (FRCM) with electromagnetic shielding characteristics using aluminum (Al) film and copper (Cu) meshes. This study investigated the electromagnetic interference (EMI) shielding effectiveness (SE) of fiber reinforced composites filled with Al film, Cu meshes, and nano carbon black as hybrid conductive fillers to provide the electromagnetic shielding property of the fiber reinforced composites. The coaxial transmission line method of ASTM D 4935-89 was used to measure the EMI shielding effectiveness of composites in the frequency range of 300 MHz to 1.5 GHz. The variations of SE of FRCM with Al film, fine Cu, and general Cu meshes are described. The results indicate that the FRCM having Al film exhibited up to 75 dB of SE at 1.5 GHz.

• 한국염색가공학회지
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• 제27권2호
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• pp.126-131
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• 2015

Silica-polyurethane hybrid breathable films were prepared and their breathabilities were assessed. Appropriately aggregated silica was prepared through sol-gel reaction of water glass and its particle size ranged 360~500nm. The polyurethane dispersion was prepared by the reaction of isophorone diisocyanate(IPDI) as diisocyanate and polytetramethylene glycol(PTMG) and dimethylol propionic acid(DMPA) as polyol, particle size ranging 30~120nm. The reaction between isocyanate and hydroxyl group to form urethane bonding was checked by the intensity of the stretch peak of isocyanate at $2270cm^{-1}$ in the FT-IR. The silica was incorporated into polyurethane dispersion and casted into film. It was shown that the incorporated silica(1~5wt.%) increased water vapour permeability of the films by 30~100%, and decreased the hydrostatic pressure by 10~40%. From the results, it could be concluded that the appropriate hybridization of silica can increase the breathability of polyurethane dispersion film, while minimizing the loss of hydrostatic pressure.

• 한국표면공학회지
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• 제44권6호
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• pp.269-276
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• 2011

Phase evolution and tribological behavior of Cr-Mo-N multi compositional films with different interlayer were investigated. The films were deposited by hybrid PVD (Physical Vapor Deposition) system consisted of dc unbalanced magnetron (UBM) sputtering and arc ion plating (AIP) sources. A pure molybdenum (Mo) was used as sputtering target and also a pure Cr was used as AIP target to form the Cr-Mo-N films. Various growth planes were found, no textured surface, in all of the multi composition films. Maximum value of microhardness was measured in Cr-Mo-N film with Mo interlayer as 29 GPa. Composition film was mainly showed the aspect of the adhesive wear than CrN film. The friction coefficient was decreased from 0.6 for pure CrN coating to 0.35 for Cr-Mo-N film with Mo interlayer. This result may come from the formation of metal oxide tribo-layer which is known as solid lubricant during the wear test.

• 대한전자공학회논문지SD
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• 제44권11호
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• pp.20-25
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• 2007

SiOC 박막과 같은 유무기 하이브리드 실리카 물질에서의 열처리효과에 의한 결합구조의 변화와 유전상수에 관하여 연구하였다. 유무기 하이브리드 실리카 물질은 BTMSM과 산소의 혼합가스를 이용한 CVD방법에 의하여 증착되었다. 유무기 하이브리드 실리카 물질은 증착조건에 따라 3가지 유형으로 분류되었으며, 유전상수는 MIS 구조에 의하여 조사되었다. XPS 분석에 의하여 C 1s 스펙트라는 O2/BTMSM=1.5의 유량비를 갖는 박막에서 282.9 eV의 organometallic carbon 반응을 보여주는 피크를 나타내었다. organometallic carbon반응의 결과는 안정성 있는 크로스 링크 결합구조를 만들어내며, 하이브리드 특성을 갖는 이 박막에서 열처리 후 유전상수는 가장 낮았다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.136.1-136.1
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• 2015

In the present study, UHF (320 MHz) in combination with RF (13.56 MHz) plasmas was used for the synthesis of hydrogenated silicon nitride (SiNx:H) films by PECVD process at low temperature. RF/UHF hybrid plasmas were maintained at a fixed pressure of 410 mTorr in the N2/SiH4 and N2/SiH4/NH3 atmospheres. To investigate the radical generation and plasma formation and their control for the growth of the film, plasma diagnostic tools like vacuum ultraviolet absorption spectroscopy (VUVAS), optical emission spectroscopy (OES), and RF compensated Langmuir probe (LP) were utilized. Utilization of RF/UHF hybrid plasmas enables very high plasma densities ~ 1011 cm-3 with low electron temperature. Measurements using VUVAS reveal the UHF source is quite effective in the dissociation of the N2 gas to generate more active atomic N. It results in the enhancement of the Si-N bond concentration in the film. Consequently, the deposition rate has been significantly improved up to 2nm/s for the high rate synthesis of highly transparent (up to 90 %) SiNx:H film. The films properties such as optical transmittance and chemical composition are investigated using different analysis tools.

• 공업화학
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• 제23권1호
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• pp.53-58
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• 2012

투명한 플라스틱 필름의 표면경도를 향상시키기 위하여 유-무기 하이브리드 코팅 용액을 졸-겔 공정을 이용하여 합성하였다. 무기성분으로 콜로이드 실리카와 유기성분으로 PMMA, 유-무기 성분 간의 결합력을 향상시켜 하이브리드 코팅 층의 특성을 더욱 향상시키기 위하여 실란커플링제로서 vinyl trimethoxy silane (VTMS)과 [3-(metha cryloyloxy)] propyl trimethoxy silane (MAPTMS)를 이용하였고, 알콕시 실란의 종류, 콜로이드 실리카/PMMA의 함량비 등의 반응조건에 따라 콜로이드 실리카/PMMA 졸을 합성하였다. 이러한 졸을 PET 필름에 바코팅시키고, 열경화 시켜 하드코팅막을 제조하여 물리적 화학적 특성을 조사하였다. PMMA에 비해서 하이브리드 형태에서 코팅 막의 연필경도와 기재와의 부착력이 우수하였다.