• 센서학회지
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• 제29권4호
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• pp.255-260
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• 2020

In this study, we developed a method of improving the surface-enhanced Raman spectroscopy (SERS) response characteristics by depositing a nanoporous Ag metal thin film through cluster source sputtering after forming a pyramidal texture structure on the Si substrate surface. A reactive ion etching (RIE) system with a metal mesh inside the system was used to form a pyramidal texture structure on the Si surface without following a complicated photolithography process, unlike in case of the conventional RIE system. The size of the texture structure increased with the RIE process time. However, after a process time of 60 min, the size of the structure did not increase but tended to saturate. When the RF power increased from 200 to 250 W, the size of the pyramidal texture structure increased from 0.45 to 0.8 ㎛. The SERS response characteristics were measured by depositing approximately 1.5 ㎛ of nanoporous Ag metal thin film through cluster sputtering on the formed texture structure by varying the RIE process conditions. The Raman signal strength of the nanoporous Ag metal thin film deposited on the Si substrate with the texture structure was higher than that deposited on the general silicon substrate by up to 19%. The Raman response characteristics were influenced by the pyramid size and the number of pyramids per unit area but appeared to be influenced more by the number of pyramids per unit area. Therefore, further studies are required in this regard.

• 전자공학회논문지
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• 제53권6호
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• pp.37-45
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• 2016

개구면 결합 마이크로스트립 패치 안테나(aperture coupled microstrip patch antenna; ACMPA)를 단위 소자로 가지는 H-평면 5소자 선형 배열 안테나의 기판 크기 변화가 방사 특성에 미치는 영향에 대하여 연구하였다. 단일 ACMPA 와 ACMPA를 단위 안테나로 가지는 H-평면 5소자 선형 배열 안테나의 전방방사 이득이 최대가 되는 패치 중심에서 E 평면 방향의 기판 가장자리까지의 길이($d_E$)와 H 평면 방향의 기판 가장자리까지의 길이($d_H$)는 서로 같음을 볼 수 있었다. 또한 선형 배열 안테나와 단일 ACMPA의 전방방사 이득이 최소가 되는 $d_E$ 와 $d_H$도 거의 같음을 볼 수 있었다. H-평면 선형 배열 안테나의 기판 크기에 따른 전방방사 이득의 변화는 $d_E$에 의해서 큰 영향을 받음을 볼 수 있었다. H-평면 선형 배열 안테나의 방사 이득이 최적화된 기판 크기는 선형 배열 안테나를 구성하는 단위 안테나의 전방방사 이득이 최적화된 기판 크기로부터 도출할 수 있음을 볼 수 있었다.

• 한국해양환경ㆍ에너지학회지
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• 제12권2호
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• pp.91-95
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• 2009

저서성 미세조류의 성장에 미치는 부착기질의 영향을 알기 위해 서로 다른 크기의 glass bead를 첨가하여 저서성 미세조류 Nitzschia sp.(진해만 클론)의 성장을 조사하였다. 연구에 사용된 glass bead의 크기는 0.09-0.15 mm(G1), 0.25-0.50 mm(G2), 0.75-1.00 mm(G3) 그리고 1.25-1.65 mm(G4)이며, glass bead를 첨가하지 않는 대조구도 설정하였다. Nitzschia sp.의 가장 높은 성장속도(0.37/day)와 최대세포밀도($9,232{\pm}840$ cells/mL)는 가장 작은 크기의 glass bead를 첨가한 G1에서 나타났다. 그리고 성징속도와 최대세포밀도는 glass bead 크기의 증가와 함께 감소하였다(G4의 성장속도와 최대세포밀도는 각각 0.24/day와 $6,397{\pm}524$ cells/mL였다). 더욱이 대조구의 성장속도는 실험구 G1에서 G3의 성장속도보다 상당히 낮았다. 이 결과에서 Nitzschia sp.와 같은 저서성 미세조류를 위한 부착기질은 성장속도 뿐만 아니라 세포밀도에도 큰 영향을 주는 것으로 나타났다. 따라서 부착미세조류의 생리실험을 위해서는 예비실험으로 부착기질의 유무 및 대상 종에 적합한 부착입자의 크기의 고려가 필요할 것으로 보인다.

• 제어로봇시스템학회논문지
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• 제14권4호
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• pp.348-352
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• 2008

Deformation of the shadow mask is one of the problems encountered during the deposition of organic materials for manufacturing large size organic light emitting diode (OLED). The larger the glass substrate, the larger the shadow mask becomes. As the size of the shadow mask increases, its deformation becomes more severe, thereby making it difficult to deposit organic materials in a precise pattern on a substrate. In this paper, a new method for reducing drooping of the shadow mask for large size OLED vapor depositions is proposed. The proposed shadow mask with cross stripe wires has higher stiffness than the pure shadow mask, which results in reducing drooping of the shadow mask. A commercial FEM program, ANSYS, is used for the evaluation of the proposed shadow mask. The analysis showed that the shadow mask with cross stripe wires have an effect on reducing drooping about 18.6% or more.

• 한국가시화정보학회지
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• 제20권3호
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• pp.19-26
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• 2022

In droplet microfluidics, precise droplet manipulation is required in numerous applications. This study presents ultrasonic surface acoustic wave (USAW)-based microfluidic device for label-free droplet separation based on size. The proposed device is composed of a slanted-finger interdigital transducer on a piezoelectric substrate and a polydimethylsiloxane microchannel placed on the substrate. The microchannel is aligned in the cross-type configuration where the USAWs propagate in a perpendicular direction to the flow in the microchannel. When droplets are exposed to an acoustic field, they experience the USAW-induced acoustic radiation force (ARF), whose magnitude varies depending on the droplet size. We modeled the USAW-induced ARF based on ray acoustics and conducted a series of experiments to separate different-sized droplets. We found that the experimental results were in good agreement with the theoretical estimation. We believe that the proposed method will serve as a promising tool for size-based droplet separation in a label-free manner.

• ETRI Journal
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• 제15권2호
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• pp.11-25
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• 1993

Interface trap densities at gate oxide/silicon substrate ($SiO_2/Si$) interfaces of metal oxide semiconductor field-effect transistors (MOSFETs) were determined from the substrate bias dependence of the subthreshold slope measurement. This method enables the characterization of interface traps residing in the energy level between the midgap and that corresponding to the strong inversion of small size MOSFET. In consequence of the high accuracy of this method, the energy dependence of the interface trap density can be accurately determined. The application of this technique to a MOSFET showed good agreement with the result obtained through the high-frequency/quasi-static capacitance-voltage (C-V) technique for a MOS capacitor. Furthermore, the effective substrate dopant concentration obtained through this technique also showed good agreement with the result obtained through the body effect measurement.

• 전기학회논문지P
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• 제58권1호
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• pp.67-71
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• 2009

This research is a new structure of the semiconductor substrate heating apparatus in which the assembly and expansion are possible. The fast thermo-responsive according to the direct heating structure of the heating plate layer adhering closely to the floor side of a substrate and the fast heat loss minimization can be accomplished. Moreover, the contact area of the sheath heater, which is the heating plate layer built-in heating apparatus, is increased, so that it has more heating valid area. There is no problem with the deformation interpreted in the state where it assembles the block of a several of the simulation result structure, the safety, and the stress. In addition, it is confirmed that building a large-size heating block is possible since the temperature deflection of the manufactured plate is lower than the standard value.

• 한국세라믹학회지
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• 제47권6호
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• pp.479-484
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• 2010

Microstructural and mechanical properties of the TiN films deposited on Si substrates under various substrate bias voltages by a reactive magnetron sputtering have been studied. It was found that the crystallographic texture, microstructural morphology and mechanical property of the TiN films were strongly depended on the substrate bias voltage. TiN films deposited without bias exhibited a mixed (200)-(111) texture with a strong (200) texture, which subsequently changed to a strong (111) texture with increasing bias voltage. It is also observed that the crystallite size decreases with increasing bias voltage, which corresponds to the increasing diffraction peak width of XRD patterns. The average surface roughness was calculated from AFM images of the films; these results indicated that the average surface roughness was increased with an increase in the bias voltage of the coatings.

• 한국표면공학회지
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• 제28권4호
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• pp.225-235
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• 1995

To investigate the effects of pretreatment and substrate bias on the characteristics of the diamond thin films, the thin films were deposited on the p-type Si(100) wafer by MPECVD using mixtures of $H_2$, $CH_4$, and $O_2$ gases. Deposition was carried out at the substrate temperature of $900^{\circ}C$ and at the pressure of 40torr. The effect of the pretreatment on the film formation was the examined by using SiC and diamond powders as abrasive powders. Furthermore, the substrate bias effect on the formation of the diamond film was also examined. The highest nucleation density was observed for the pretreatment with 40~60$\mu\textrm{m}$ size of diamond powders and a negative bias potential(-50V). Many defects and(111) twins in the diamond films were observed.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권5호
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• pp.2346-2361
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• 2017

A major challenge in cloud infrastructure is the efficient allocation of virtual network elements on top of substrate network elements. Path algebra is a mathematical framework which allows the validation and convergence analysis of the mono-constraint or multi-constraint routing problems independently of the network topology or size. The present study proposes a new heuristic approach based on mathematical framework "paths algebra" to map virtual nodes and links to substrate nodes and paths in cloud. In this approach, we define a measure criterion to rank the substrate nodes, and map the virtual nodes to substrate nodes according to their ranks by using a greedy algorithm. In addition, considering multi-constraint routing in virtual link mapping stage, the used paths algebra framework allows a more flexible and extendable embedding. Obtained results of simulations show appropriate improvement in acceptance ratio of virtual networks and cost incurred by the infrastructure networks.