• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2010년도 춘계학술대회 논문집
• /
• pp.709-710
• /
• 2010

• 한국미생물·생명공학회지
• /
• 제7권4호
• /
• pp.211-216
• /
• 1979

단세포 단백질의 합성이나 환성오니법에 의한 폐수처리 등에 응용되고 있는 Air-lift Fermentor (ALF)는 일반적인 기계식 교반 발효조에 비하여 산소전달 효과가 우수한 것으로 알려져 있다. 그러나 미생물의 성장반응에는 적절한 교반이 필요하므로 발효조 내에서는 높은 산소 농도와 함께 활발한 교반이 이루어져야 한다. 본 연구에서는 ALF 내에서의 산소전달에만 국한해오던 연구 방향에서 실제로 Methylomonas, sp를 이용한 methanol fermentation을 행하여 이 발효조의 기능을 조사하였다. 그 결과 교반은 활발히 일어나고 있으나 높은 농도의 산소를 얻기 위해서는 높은 압력하에서나 낮은 dilution rate에서 운전하여야 하는 것으로 나타났다.

• Journal of Mechanical Science and Technology
• /
• 제20권9호
• /
• pp.1492-1501
• /
• 2006

A transportation system of single wafer has been developed to be applied to semiconductor manufacturing process of the next generation. In this study, the experimental apparatus consists of two kinds of track, one is for propelling a wafer, so called control track, the other is for generating an air film to transfer a wafer, so called transfer track. The wafer transportation speed has been evaluated by the numerical and the experimental methods for three types of nozzle position a..ay (i.e., the front-, face- and rear-array) in an air levitation system. Test facility for 300mm wafer has been equipped with two control tracks and one transfer track of 1500mm length from the starting point to the stopping point. From the present results, it is found that the experimental values of the wafer transportation speed are well in agreement with the computed ones. Namely, the computed values of the maximum wafer transportation speed $V_{max}$ are slightly higher than the experimental ones by about $15{\times}20%$. The disparities in $V_{max}$ between the numerical and the experimental results become smaller as the air velocity increases. Also, at the same air flow rate, the order of wafer transportation speeds is : $V_{max}$ for the front-array > $V_{max}$ for the face-array > $V_{max}$ for the rear-array. However, the face-array is rather more stable than any other type of nozzle array to ensure safe transportation of a wafer.

• Biotechnology and Bioprocess Engineering:BBE
• /
• 제6권1호
• /
• pp.42-50
• /
• 2001

The activity of immobilized cell-support particle aggregates is influenced by physical and biochemical elements, mass transfer, and physiology. Accordingly, the mathematical model discussed in this study is capable of predicting the steady state and transient concentration profiles of the cell mass and substrate, plus the effects of the substrate and product inhibition in an immobilized cell-support aggregate. The overall mathematical model is comprised of material balance equations for the cell mass, major carbon source, dissolved oxygen, and non-biomass products in a bulk suspension along with a single particle model. A smaller bead size and higher substrate concentration at the surface of the particle, resulted in a higher supply of the substrate into the aggregate and consequently a higher biocatalyst activity.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
• /
• pp.372-372
• /
• 2012

We have studied a fabrication of Poly (3,4-ethylenedioxythiophene) (PEDOT) wire arrays and structures with various feature sizes from hundreds micrometers to tens nanometers. PEDOT is well-known as a conducting material, can be grown by a vapor pressure polymerization (VPP) method. The VPP technique is a bottom-up processing method that utilizes the organic arrangement of macromolecules to easily produce ordered aggregates. Also, liquid-bridge-mediated nanotransfer molding (LB-nTM), which was reported as a new direct patterning method recently, is based on the direct transfer of various materials from a mould to a substrate through a liquid bridge between them. The PEDOT nanowires grown by VPP method and transferred on a substrate to use LB-nTM method have been investigated by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Selected Area Electron Diffraction (SAED), X-Ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), and electrical properties.

• 전기학회논문지
• /
• 제59권2호
• /
• pp.359-362
• /
• 2010

In this study, inverter logic circuits on a plastic substrate are built with two top-gate FETs in series on a single ZnO nanowire. The voltage transfer characteristics of the ZnO nanowire-based inverter logic circuit exhibit a clear inverting operation. The logic swing, gain and transition width of the inverter logic circuit is about 90 %, 1.03 and 1.2 V, respectively. The result of mechanical bending cycles of the inverter logic circuit on a plastic substrate shows that the stable performance is maintained even after many hundreds of bending cycles.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
• /
• pp.561-561
• /
• 2012

Graphene, two dimensional single layer of carbon atoms, has tremendous attention due to its superior property such as fast electron mobility, high thermal conductivity and optical transparency, and also found many applications such as field-effect transistors (FET), energy storage and conversion, optoelectronic device, electromechanical resonators and chemical sensors. Several techniques have been developed to form the graphene. Especially chemical vapor deposition (CVD) is a promising process for the large area graphene. For the electrically isolated devices, the graphene should be transfer to insulated substrate from Cu or Ni. However, transferred graphene has serious drawback due to remaining polymeric residue during transfer process which induces the poor device characteristics by impurity scattering and it interrupts the surface functionalization for the sensor application. In this study, we demonstrate the characteristics of solution-gated FET depending on the removal of polymeric residues. The solution-gated FET is operated by the modulation of the channel conductance by applying a gate potential from a reference electrode via the electrolyte, and it can be used as a chemical sensor. The removal process was achieved by several solvents during the transfer of CVD graphene from a copper foil to a substrate and additional annealing process with H2/Ar environments was carried out. We compare the properties of graphene by Raman spectroscopy, atomic force microscopy(AFM), and X-ray Photoelectron Spectroscopy (XPS) measurements. Effects of residual polymeric materials on the device performance of graphene FET will be discussed in detail.

• 한국재료학회지
• /
• 제28권11호
• /
• pp.627-632
• /
• 2018

Two dimensional(2D) crystals, composed of a single layer or a few atomic layers extracted from layered materials are attracting researchers' interest due to promising applications in the nanoelectromechanical systems. Worldwide researchers are preparing devices with suspended 2D materials to study their physical and electrical properties. However, during the fabrication process of 2D flakes on a target substrate, contamination occurs, which makes the measurement data less reliable. We propose a dry transfer method using poly-methyl methacrylate(PMMA) for the 2D flakes to transfer onto the targeted substrate. The PMMA is then removed from the device by an N-Methyl-2-pyrrolidone solution and a critical point dryer, which makes the suspended 2D flakes residue free. Our method provides a clean, reliable and controllable way of fabricating micrometer-sized suspended 2D nanosheets.

• Journal of Microbiology and Biotechnology
• /
• 제21권12호
• /
• pp.1257-1263
• /
• 2011

This paper is dedicated to the study on the external and internal mass transfers of glucose for succinic acid fermentation under substrate and product inhibitions using a bioreactor with stirred bed of immobilized Actinobacillus succinogenes cells. By means of the substrate mass balance for a single particle of biocatalysts, considering the kinetic model adapted for both inhibitory effects, specific mathematical models were developed for describing the profiles of the substrate concentration in the outer and inner regions of biocatalysts and for estimating the substrate mass flows in the liquid boundary layer surrounding the particle and inside the particle. The values of the mass flows were significantly influenced by the internal diffusion velocity and rate of the biochemical reaction of substrate consumption. These cumulated influences led to the appearance of a biological inactive region near the particle center, its magnitude varying from 0 to 5.3% of the overall volume of particles.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
• /
• pp.637-637
• /
• 2013

We develop single-crystal poly(3,4-ethylenedioxythiopene nanowires using liquid-bridge-mediated nanotransfer printing via vapor phase polymerization. This direct printing method can simultaneously enable the synthesis, alignment and patterning of the nanowires from molecular ink solutions. Twoor three-dimensional complex structures of various single-crystal organic nanowires were directly fabricated over a large area using many types of molecular inks. This method is capable of generating several optoelectronic devices. LB-nTM is based on the direct transfer of various materials from a mold to a substrate via a liquid bridge between them. To demonstrate its usefulness, we used LB-nTM to fabricate nanowire field-effect transistors and arrays of 6,13-bis (triisopropyl- silylethynyl) pentacene (TIPS-PEN) nanowire field-effect transistors.