• Journal of the Korean Vacuum Society
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• v.11 no.2
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• pp.113-118
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• 2002

We developed engineering methods to control gas flow in a plasma reactor in order to achieve good etch depth uniformity for large area GaAs etching. Finite difference numerical method was found quite useful for simulation of gas flow distribution in the reactor for dry etching of GaAs. The experimental results in $BCl_3/N_2/SF_6/He$ ICP plasmas confirmed that the simulated data fitted very well with real data. It is noticed that a focus ring could help improve both gas flow and etch uniformity for 150 mm diameter GaAs plasma etch processing. The simulation results showed that optimization of clamp configuration could decrease gas flow uniformity as low as $\pm$ 1.5% on an 100 mm(4 inch) GaAs wafer and $\pm$ 3% for a 150 m(6 inch) wafer with the fixed reactor and electrode, respectively. Comparison between simulated gas flow uniformity and real etch depth distribution data concluded that control of gas flow distribution in the chamber would be significantly important in order or achieve excellent dry etch uniformity of large area GaAs wafers.

• Journal of Korean Society for Atmospheric Environment
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• v.16 no.2
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• pp.191-198
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• 2000

For a characterization of the pretreated waste automotive catalyst the following analysis techniques were applied : EA(Elemental Analysis) BET(Brunaure-Emmett-Teller) and ICP-AES(Inductively Coupled Plasma-Atomic Emission Spectrometry). The combustion activity of waste automotive catalyst was investigated for methanol acetaldehyde and toluene as model VOCs in a fixed bed reactor. carbon deposit amount was decreased with increasing catalyst showed a good catalytic activity for VOCs combustion at 40$0^{\circ}C$. Catalytic activity for methanol acetaldehyde and toluence combustion was very excellent and decreased with mileage. The catalytic activity of a waste automotive catalyst for methanol combustion increased after acid treatment. The acid effect of catalytic activity was summarized as follows: HNO3>HCI>H2SO4>CH3COOH. The waste automotive catalyst regenerated by the pretreatment method might have a excellent catalytic activity for VOCs combustion.

• Journal of the Korean Vacuum Society
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• v.4 no.2
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• pp.210-216
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• 1995

최근에 연구되고 있는 저온, 저압 플라즈마를 이용한 식각기술 중 차세대 반도체 metallization 공정에 응용될 수 있는 가장 적합한 기술이라 사료되는 유도 결합형 플라즈마(Inductively Coupled Plasma : ICP)를 이용한 RF 스퍼터 식각 반응로를 제작하고 이에 대한 특성을 조사하였다. 유도용 주파수로서 13.56 MHz를 사용하였으며 유도결합을 일으키기 위해 3.5회의 나선형 평판형 코일을 사용함으로써 비교적 대면적에 균일한 고밀도 플라즈마를 얻을 수 있었다. 또한 기판에 독립적인 13.56MHz RF power를 가해 DC 바이어스를 인가함으로써 기판으로 입사하는 하전입자들의 에너지를 조절하여 기판에의 손상을 최소화하며 SiO2의 스퍼터 식각 속도를 극대화할 수 있었다. 따라서 이러한 특성을 갖는 유도 결합형 플라즈마 식각장치를 차세대 반도체의 RF스퍼터 식각 공정에 응용할 수 있으리라 사료된다.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.5
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• pp.819-825
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• 2000

The physico-chemical characteristics and the combustion activities of a waste automotive catalyst were carried out in this study. The physico-chemical characteristics of waste automotive catalyst was examined by EA(Elemental analysis), ICP-AES (Inductively coupled plasma-atomic emission spectrophotometer), and XRD(X-ray diffraction) analysis. Carbon deposit amount was higher in front brick than rear brick of catalyst, and increased with mileage. The content of Pt. Pd and Rh in waste automotive catalyst was different from the car manufacturing company. The combustion activities of waste automotive catalyst were investigated for acetaldehyde as a model VOC in a fixed bed reactor at atmospheric pressure. The catalytic activity of rear brick for acetaldehyde combustion was better than front brick of waste automotive catalyst. The catalytic activity of waste automotive catalyst for acetaldehyde combustion decreased with mileage. The linear relationship between catalytic activity and mileage was negative and has a very excellent correlation. Finally, the waste automotive catalyst has a good catalytic activity for acetaldehyde combustion. and can be used to control of small emission source.

• Journal of the Korean Society of Groundwater Environment
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• v.5 no.2
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• pp.116-121
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• 1998

For the application of study on pollution and conservation of environment determination of 33 elemental concetrations in different sediment samples were carried out using instrumental neutron activation analysis (INAA). For verification and evaluation of the analytical method, three standard reference materials (two NIST SRMs and one NRCC CRM) were chosen and the accuracy and precision of the analysis were estimated by comparison to the certified values. Under the optimum condition, the analytical procedure to apply a practical sample was estimated. Neutron irradiation of sample was done at the irradiation facilities (neutron flux, 1-3${\times}$10$\^$13/n/$\textrm{cm}^2$$.$s) of the TRIGA MARK-III and HANARO research reactor in the Korea Atomic Energy Research Institute. In addition, analysis of two IAEA's sediment was performed according to the pre-established analytical method. The analytical results of elements such as Al, As, Co, Cr, Fe, Sb and Zn by INAA were intercompared with those of WD-XRF, ICP-MS and AAS, and are relatively agreed with each other.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.12S
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• pp.1187-1194
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• 2003

A BCl$_3$/Ne plasma chemistry was used to etch Ga-based (GaAs, AIGaAs, GaSb) and In-based (InGaP, InP, InAs and InGaAsP) compound semiconductors in a Planar Inductively Coupled Plasma (ICP) reactor. The addition of the Ne instead of Ar can minimize electrical and optical damage during dry etching of III-V semiconductors due to its light mass compared to that of Ar All of the materials exhibited a maximum etch rate at BCl$_3$ to Ne ratios of 0.25-0.5. Under all conditions, the Ga-based materials etched at significantly higher rates than the In-based materials, due to relatively high volatilities of their trichloride etch products (boiling point CaCl$_3$ : 201 $^{\circ}C$, AsCl$_3$ : 130 $^{\circ}C$, PCl$_3$: 76 $^{\circ}C$) compared to InCl$_3$ (boiling point : 600 $^{\circ}C$). We obtained low root-mean-square(RMS) roughness of the etched sulfate of both AIGaAs and GaAs, which is quite comparable to the unetched control samples. Excellent etch anisotropy ( > 85$^{\circ}$) of the GaAs and AIGaAs in our PICP BCl$_3$/Ne etching relies on some degree of sidewall passivation by redeposition of etch products and photoresist from the mask. However, the surfaces of In-based materials are somewhat degraded during the BCl$_3$/Ne etching due to the low volatility of InCl$_{x}$./.

• Korean Chemical Engineering Research
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• v.49 no.6
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• pp.739-744
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• 2011

Activated carbon SCR(CSCR) catalyst that is used to remove $NO_x$ in exhaust gas including boron discharged from the production process of liquid crystal display(LCD) shows deactivation when boron is deposited to block the pores within the catalyst or to cover its active sites. The spent carbon catalyst is regenerated by washing with various surfactants, drying and calcination. For comparison of the physical and chemical properties before and after the regeneration with the variables, type of surfactants and calcination condition, element analysis by ICP, $N_{2}$ adsorption were conducted. $DeNO_{x}$ in SCR with $NH_3$ was carried out in a fixed bed reactor at $120^{\circ}C$. The activated carbon catalyst regenerated through washing with a non-ionic surfactant in $H_{2}O$ at $90^{\circ}C$ and calcination under $N_{2}$ gas at $550^{\circ}C$ shows similar level of surface area and $NO_x$ removal efficiency with those of fresh catalyst.

• Nuclear Engineering and Technology
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• v.42 no.1
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• pp.79-88
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• 2010

Spent $UO_2$ nuclear fuel discharged from a nuclear power plant (NPP) contains fission products, U, Pu, and other actinides. Due to neutron capture by $^{238}U$ in the rim region and a temperature gradient between the center and the rim of a fuel pellet, a considerable increase in the concentration of fission products, Pu, and other actinides are expected in the pellet periphery of high burnup fuel. The characterization of the radial profiles of the various isotopic concentrations is our main concern. For an analysis, spent nuclear fuels originating from the Yeonggwang-2 pressurized water reactor (PWR) were chosen as the test specimens. In this work, the distributions of some actinide isotopes were measured from center to rim of the spent fuel specimens by a radiation shielded laser ablation inductively coupled plasma mass spectrometer (LA-ICP-MS) system. Sampling was performed along the diameter of the specimen by reducing the sampling intervals from 500 ${\mu}m$ in the center to 100 ${\mu}m$ in the pellet periphery region. It was observed that the isotopic concentration ratios for minor actinides in the center of the specimen remain almost constant and increase near the pellet periphery due to the rim effect apart from the $^{236}U$ to $^{235}U$ ratio, which remains approximately constant. In addition, the distributions of local burnup were derived from the measured isotope ratios by applying the relationship between burnup and isotopic ratio for plutonium and minor actinides calculated by the ORIGEN2 code.

• Applied Chemistry for Engineering
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• v.27 no.2
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• pp.165-170
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• 2016

In this study, we investigated the cause of the decrease in activities of $VO_x/TiO_2$ SCR catalyst used for the burner reactor at a scale of $150000Nm^3/hr$ using X-ray diffraction (XRD), brunauer-emmett-teller (BET), atomic emission spectroscopy inductively coupled plasma (AES ICP), $H_2$ temperature programmed reduction ($H_2$-TPR), and $NH_3$ temperature programmed desorption ($NH_3$-TPD) analysis. Since the crystallization of the $VO_x$ and phase transition of $TiO_2$ did not occur, it was concluded that the catalyst was not deactivated by the thermal effect. In addition, from the elemental analysis showing that a large quantity of calcium was detected but not sulfur, the deactivation process of the $VO_x/TiO_2$ SCR catalyst was mainly caused by Ca but not by $SO_2$. The calcium was also found to decrease the catalytic activity by means of reducing $NH_3$ adsorption.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.245-245
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• 2012

Syntheses of oxide supported metal catalysts by wet-chemical routes have been well known for their use in heterogeneous catalysis. However, uniform deposition of metal nanoparticles with controlled size and shape on the support with high reproducibility is still a challenge for catalyst preparation. Among various synthesis methods, arc plasma deposition (APD) of metal nanoparticles or thin films on oxide supports has received great interest recently, due to its high reproducibility and large-scale production, and used for their application in catalysis. In this work, Au and Pt nanoparticles with size of 1-2 nm have been deposited on titania powder by APD. The size of metal nanoparticles was controlled by number of shots of metal deposition and APD conditions. These catalytic materials were characterized by x-ray diffraction (XRD), inductively coupled plasma (ICP-AES), CO-chemisorption and transmission electron microscopy (TEM). Catalytic activity of the materials was measured by CO oxidation using oxygen, as a model reaction, in a micro-flow reactor at atmospheric pressure. We found that Au/$TiO_2$ is reactive, showing 100% conversion at $110^{\circ}C$, while Pt/$TiO_2$ shows 100% conversion at $200^{\circ}C$. High activity of metal nanoparticles suggests that APD can be used for large scale synthesis of active nanocatalysts. We will discuss the effect of the structure and metal-oxide interactions of the catalysts on catalytic activity.