• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2000.11a
• /
• pp.363-366
• /
• 2000

In this study, SrBi$_2$Ta$_2$$O_{9}$ (SBT) thin films were etched at different Cl$_2$gas mixing ratio in Cl$_2$/Ar. The maximum etch rate of SBT was 883 $\AA$/min in Cl$_2$(20%)/Ar(80%). The result indicates that physical sputtering of charged particles is dominant to chemical reaction in etching SBT thin films. To evaluate the changes of morphology and crystallinity on the near surface of etched SBT, atomic force microscopy (AFM) and x-ray diffraction (XRD) were used. The rms values of etched samples in Ar only or Cl$_2$ only plasma were higher than that of as-deposited, Cl$_2$/Ar Plasma. The SBT (105) crystalinity of the etched samples decreased in Af only or Cla only plasma, but maintain constant in ClyAr plasma. This can be illustrated by a decrease of Bi content or nonvolatile etching products (Sr-Cl and Ta-Cl), resulting in the changes of stoichiometry on the etched surface of the SBT thin films. The decrease of Bi content and nonvolatile etch products were revealed by x-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS).).

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09a
• /
• pp.487-488
• /
• 2006

Novel bisphenol-based wholly aromatic poly(ether sulfone-ketone) copolymer containing pendant sulfonate groups were prepared by direct aromatic nucleophilic substitution polycondensation of 4,4-difluorobenzophenone, 2,2'-disodiumsulfonyl-4,4'-fluorophenylsulfone (40mole% of bisphenol A) and bisphenol A. Polymerization proceeded quantitatively to high molecular weight in N-methyl-2-pyrrolidinone at $180^{\circ}C$. Organic-inorganic composite membranes were obtained by mixing organic polymers with hydrophilic $SiO_2$ (ca. 20nm) obtained by sol-gel process. The polymer and a series of composite membranes were studied by FT-IR, $^1HNMR$, differential scanning calorimetry (DSC) and thermal stability. The proton conductivity as a function of temperature decreased as $SiO_2$ content increased, but methanol permeability decreased. The nano composite membranes were found to posse all requisite properties; Ion exchange capacity (1.2meq./g), glass transition temperatures $(164-183\;^{\circ}C)$, and low affinity towards methanol $(4.63-1.08{\times}10^{-7}\;cm^2/S)$.

• Transactions on Electrical and Electronic Materials
• /
• v.14 no.2
• /
• pp.67-70
• /
• 2013

In this study, we changed the input parameters (gas mixing ratio, RF power, DC bias voltage, and process pressure), and then monitored the effect on TiN etch rate and selectivity with $SiO_2$. When the RF power, DC-bias voltage, and process pressure were fixed at 700 W, - 150 V, and 15 mTorr, the etch rate of TiN increased with increasing $CF_4$ content from 0 to 20 % in $CF_4$/Ar plasma. The TiN etch rate reached maximum at 20% $CF_4$ addition. As RF power, DC bias voltage, and process pressure increased, all ranges of etch rates for TiN thin films showed increasing trends. The analysis of x-ray photoelectron spectroscopy (XPS) was carried out to investigate the chemical reactions between the surfaces of TiN and etch species. Based on experimental data, ion-assisted chemical etching was proposed as the main etch mechanism for TiN thin films in $CF_4$/Ar plasma.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.24 no.6
• /
• pp.445-448
• /
• 2011

In this study, the etching characteristics of $Al_2O_3$ thin films were investigated using an ICP (inductively coupled plasma) of $BCl_3$/Ar gas mixture. The etch rate of $Al_2O_3$ thin films as well as the $SiO_2/Al_2O_3$ etch selectivity were measured as functions of $BCl_3$/Ar mixing ratio (0~100% Ar) at a constant gas pressure (10 mTorr), total gas flow rate (40 sccm), input power (800 W) and bias power (100 W). The behavior of the $Al_2O_3$ etch rate was shown to be quite typical for ion-assisted etch processes with a dominant chemical etch pathway. To analyze the etching mechanism using DLP (double langmuir probe), OES (optical emission spectroscopy) and surface analysis using XPS (x-ray photoelectron spectroscopy) were carried out.

• Journal of Korean Society of Water and Wastewater
• /
• v.13 no.1
• /
• pp.51-60
• /
• 1999

An intermittently-aerated, intermittently-decanted single-reactor process (KIDEA process : KIST intermittently decanted extended aeration process) was applied for nitrogen removal from wastewater. Synthetic wastewater with chemical oxygen demand (COD): nitrogen (N) ratio of approximately 5.25: 1 was used. The average COD removal efficiency reached above 95%, and under optimal conditions nitrogen removal efficiency also reached above 90%. This process consisted of 72 minute aeration, 48 minute settling and 24 minute effluent decanting with continuous feeding of influent wastewater from the bottom of the reactor, and did not require a separate anoxic mixing-phase. In this process, nitritation ($1^{st}$ step of nitrification) was induced but nitratation($2^{nd}$ step of nitrification) was suppressed. Main factors responsible for the accumulation of nitrite ion in the experimental condition were free ammonium and dissolved oxygen. This condition of nitrite build-up accelerated by continuous feed flow in the bottom of the KIDEA reactor because of high concentration of ammonia nitrogen in the influent. This research provides one of answers to control nitrate build-up.

• Electronics and Telecommunications Trends
• /
• v.34 no.5
• /
• pp.99-112
• /
• 2019

A quantum light source is an essential element for quantum information technology, including quantum communication, quantum sensor, and quantum computer. Quantum light sources including photon number state, entangled state, and squeezed state can be divided into two types according to the generation mechanism, namely single emitter and non-linear based systems. The single emitter platform contains atom/ion trap, solid-state defect/color center, two-dimensional material, and semiconductor quantum dot, which can emit deterministic photons. The non-linear based platform contains spontaneous parametric down-conversion and spontaneous four-wave mixing, which can emit probabilistic photon pairs. For each platform, we give an overview of the recent research trends of the generation, manipulation, and integration of single photon and entangled photon sources. The characteristics of quantum light sources are investigated for each platform. In addition, we briefly introduce quantum sensing, quantum communication, and quantum computing applications based on quantum light sources. We discuss the challenges and prospects of quantum light sources for quantum information technology.

• KEPCO Journal on Electric Power and Energy
• /
• v.7 no.2
• /
• pp.295-299
• /
• 2021

Recently, interest in maintenance has been increasing due to the enlargement and aging of infra structures. Therefore, a new paradigm is required to secure and improve the durability of structures differentiated from the past. Accordingly, research on smart concrete incorporating the concept of self-healing into concrete is being actively conducted. In this study, the crack healing performance and durability performance of self-healing concrete applied with a hydrogel containing biomineral-forming microorganisms were evaluated. As a result of evaluating the dispersion of the hydrogel in concrete, it was confirmed that the hydrogel was well distributed in concrete matrix with a dispersion coefficient of 0.35 to 0.46. The crack healing performance evaluation was verified by a water permeability test, and showed a recovery rate of 95% or more at the age of 28 days, confirming the applicability of self-healing concrete. The durability performance of self-healing concrete was evaluated in terms of resistance to penetration of chloride ion and freezing and thawing. Regardless of the mixing of the hydrogel, the same level of durability performance was shown for various compressive strength level. Therefore, it was confirmed that the microbial admixture did not affect concrete durability. In the future, long-term crack healing performance and durability verification studies should be supplemented.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2000.02a
• /
• pp.164-164
• /
• 2000

Since Au-Pt alloys have various atomic structures depending upon composition and annealing temperature, it is very interesting to investigate the electronic structures of alloys. We studied the changes of the electronic structure I the Au-Pt alloys by x-ray absorption near edge spectroscopy (XANES). Two kinds of Au-Pt alloy samples were prepared by arc melting methods and ion-beam-mixing technique. The Pt L2, 3-edge and Au L2, 3-edge X-ray absorption spectra (XPS) were measured with the electron yield mode detector at the 3C1 beam line of the Pohang Light Source (PLS). It was found that there was a substantial decrease in the area of the Pt L2, 3 white lines compared with that of pure Pt. The observed decrease in white line area was attributed to an increase in the number of pure Pt. The observed decrease in white line area was attributed to an increase in the number of 5d-electrons at the Pt site upon alloy formation. However, the Au L2, 3 edge spectra for Au-Pt alloys are all similar to that of pure Au. This implies that the 5d hole count of Au is not changed by alloy formation with Pt.

• Korean Journal of Materials Research
• /
• v.4 no.8
• /
• pp.934-944
• /
• 1994

Effects of residual chloride on thermal decomposition behaviour of a-stannic acid and physical properties of $SnO_{2}$ powder were observed. The powder was fabricated by hydroxide method; $\alpha$-stannic acid was precipitated by mixing acqueous solutions of $SnCl_{4}$ and $NH_{4}$OH . The precipitate was washed with $NH_{4}NO_{3}$ solution while washing was controlled to be of three grades to modify its residual chloride content. The precipitate was dried at $1100^{\circ}C$ ~ 24h and calcined in air at $500^{\circ}C$ ~ $1100^{\circ}C$ for one hour. Thermal decomposition behaviour of $\alpha$-stannic acid was examined by a DT-TGA and a FTIR. Chemical composition and physical properties of $SnO_{2}$ powder were observed by an AES, a BET and a TEM, respectively. With a reduction in chloride content, the relative crystallite size of $SnO_{2}$ powder slightly increased by a low-temperature-calcining. However, at a high calcining temperature(T), the reverse relation occured. It was suggested that chloride ion replaces part of lattice oxygen site of a-stannic acid. Also, chloride ion on the site was suggested to retard de-hydration as well as crystalization at a low T while to promote crystal growth of $SnO_{2}$ by forming oxygen vacancy at a high T.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.23 no.7
• /
• pp.113-119
• /
• 2019

Concrete structures built on reclaimed land are combined with chemical erosion such as chlorine and sulfate ions from seawater. Chloride attack deteriorates the performance of the structure by corroding reinforcing bars. In addition, the waste water treatment structure has a problem that the concrete is deteriorated by the sulfate generated inside. Therefore, in this study, the characteristics and chemical resistance of low heat cement concrete used in wastewater treatment structures constructed on reclaimed land were evaluated. As a result of the experiment, the target slump and air content were satisfied under all the mixing conditions. The slump of low heat cement (LHC) concrete was higher than that of ordinary portland cement (OPC) concrete, while the air content of LHC concrete was smaller than that of OPC concrete with the same mix proportion. As a result of compressive strength test, OPC concrete showed higher strength at younger age compared to 28 days. In contrast, LHC concrete exhibited higher strength than OPC concrete at the age of 56 days. As a result of chlorine ion penetration tests, LHC-B concrete showed chlorine ion penetration resistance performance of the "very low" level at the age of 56 days. As a result of chemical resistance evaluation, when the LHC concrete is applied without epoxy treatment, chemical resistance is improved by about 18% compared to OPC concrete. In testing chemical resistance, the epoxy coated concrete exhibited less than 5% strength reduction when compared to sound concrete.