• Proceedings of the Korean Radioactive Waste Society Conference
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• 2018.05a
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• pp.57-57
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• 2018

The electrorefining process is generally composed of two recovery steps in pyroprocessing - the deposit of uranium onto a solid cathode and the recovery of the remaining uranium and TRU elements simultaneously by a liquid cadmium cathode. The liquid cathode processing is necessary to separate cadmium from the actinide elements since the actinide deposits are dissolved or precipitated in a liquid cathode. Distillation process was employed for the cathode processing. It is very important to avoid a splattering of cadmium during evaporation due to the high vapor pressure. In this study, a multi-layer porous round cover was proposed and examined to develop a splatter shield for the Cd distillation crucible. Cadmium vapor can be released through the holes of the shield, whereas liquid drops can be collected in the multiple hemisphere. The collected drops flow on the round surface of the cover and flow down into the crucible. The crucible cover was fabricated and tested in the Cd distiller. The cover was made with three stainless steel round plates with a diameter of 33.50 mm. The distance between the hemispheres and the diameter of the holes are 10 and 1 mm, respectively. About 40 grams of Cd and about 4 grams of Bi was distilled at a reduced pressure for two hours at $470^{\circ}C$. After the Cd distillation experiment, cadmium was not detected and more than 90 % of Bi remained in the ICP-OES analysis. Therefore the crucible cover can be a candidate for the splatter shield of the Cd distillation crucible. Further development of the crucible cover is necessary for the decision of the optimum cover geometry and the operating conditions of the Cd distiller.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.12
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• pp.924-928
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• 2010

In this study, $HfAlO_3$ thin films using gate insulator of MOSFET were etched in inductively coupled plasma. The etch characteristics of the $HfAlO_3$ thin films has been investigated by varying $O_2/BCl_3$/Ar gas mixing ratio, a RF power, a DC bias voltage and a process pressure. As the $O_2$ concentration increases further, $HfAlO_3$ was redeposited. As increasing RF power and DC bias voltage, etch rates of the $HfAlO_3$ thin films increased. Whereas, as decreasing of the process pressure, etch rates of the $HfAlO_3$ thin films increased. The chemical reaction on the surface of the etched the $HfAlO_3$ thin films was investigated with X-ray photoelectron spectroscopy (XPS). These peaks moved a binding energy. This chemical shift indicates that there are chemical reactions between the $HfAlO_3$ thin films and radicals and the resulting etch by-products remain on the surface.

• Progress in Superconductivity and Cryogenics
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• v.13 no.4
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• pp.30-35
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• 2011

This paper describes experimental study and performance improvement of 2 stage Gifford-McMahon (G-M) type pulse tube cryocooler for cryopump. The objective of this study is to improve the efficiency of 2 stage pulse tube cryocooler for substituting 2 stage G-M cryocooler used in cryopump. The target cooling capacities are 5 W at 20 K and 35 W at 80 K for the $1^{st}$ and the $2^{nd}$ stage, respectively. These values are good cooling capacities for vacuum level in medium size ICP 200 cryopump. Design of the 2 stage pulse tube cryocooler is conducted by FZKPTR(Forschungs Zentrum Karlsruhe Pulse Tube Refrigerator) program. In order to improve the performance of 2 stage pulse tube cryocooler, U-type pulse tube cryocooler is fabricated and connecting tubes are minimized for reducing dead volumes and pressure losses. Also, to get larger capacities, orifice valves and double inlet valves are optimized and the compressor of 6 kW is used. On the latest unit, the lowest temperatures of 2 stage pulse tube cryocooler are 42 K ($1^{st}$ stage) and 8.3 K ($2^{nd}$ stage) and the cooling capacities are 40 W at 82.9 K ($1^{st}$ stage) and 10 W at 20.5 K ($2^{nd}$ stage) with 6.0 kW of compressor input power. This pulse tube cryocooler is suited for commercial medium size cryopump. In performance test of cryopump with 2 stage pulse tube cryocooler, pumping speed for gaseous nitrogen is 4,300 L/s and the ultimate vacuum pressure is $7.5{\times}10^{-10}$ mbar.

• Journal of Korean Neurosurgical Society
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• v.44 no.3
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• pp.141-145
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• 2008

Objective : Barbiturate coma therapy (BCT) has been known to be an useful method to control increased intracranial pressure (IICP) refractory to medical and surgical treatments. We have used BCT for patients with severe IICP during the past 10 years, and analyzed our results with review of literatures. Methods : We analyzed 92 semicomatose or comatose patients with Glasgow coma scale (GCS) of 7 or less with severe IICP due to cerebral edema secondary to parenchymal damages irrespective of their causes. Forty patients who had received BCT with ICP monitoring from January 1997 to December 2006 were included in BCT group, and fifty-two patients who had been managed without BCT from January 1991 to December 1995 were divided into control group. We compared outcomes with Glasgow outcome scale (GOS) and survival rate between the two groups. Results : Good outcome (GOS=4 and 5) rates at 3-month after insult were 27.5% and 5.8% in BCT and control group, respectively (p<0.01). One-year survival rates were 35.9% and 12.5% in BCT and control group, respectively (p<0.01). In BCT group, the mean age of good outcome patients ($37.1{\pm}14.9$) was significantly lower than that of poor outcome patients ($48.1{\pm}13.5$) (p<0.05). Conclusion : With our 10-year experience, we suggest that BCT is an effective treatment method for severe IICP patients for better survival and GOS, especially for younger patients.

• Journal of the Korean institute of surface engineering
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• v.42 no.6
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• pp.256-259
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• 2009

The wafer surface temperature is an important parameter in the etching process which influences the reaction probabilities of incident species, the vapor pressure of etch products, and the re-deposition of reaction products on feature surfaces. In this study, we investigated all of the effects of substrate temperature on the etch rate of $ZrO_2$ thin film and selectivity of $ZrO_2$ thin film over $SiO_2$ thin film in inductively coupled plasma as functions of $Cl_2$ addition in $BCl_3$/Ar plasma, RF power and dc-bias voltage based on the substrate temperature in range of $10^{\circ}C$ to $80^{\circ}C$. The elements on the surface were analyzed by x-ray photoelectron spectroscopy (XPS).

• Journal of Korean Neurosurgical Society
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• v.45 no.4
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• pp.240-242
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• 2009

Oculomotor nerve palsy (ONP) with subarachnoid hemorrhage (SAH) occurs usually when oculomotor nerve is compressed by growing or budding of posterior communicating artery (PcoA) aneurysm. Midbrain injury, increased intracranial pressure (lCP), or uncal herniation may also cause it. We report herein a rare case of ONP associated with SAH which was caused by middle cerebral artery (MCA) bifurcation aneurysm rupture. A 58-year-old woman with clear consciousness suffered from headache and sudden onset of unilateral ONP. Computed tomography showed SAH caused by the rupture of MCA aneurysm. The unilateral ONP was not associated with midbrain injury, increased ICP, or uncal herniation. The patient was treated with coil embolization, and the signs of oculomotor nerve palsy completely resolved after a few days. We suggest that bloody jet flow from the rupture of distant aneurysm other than PcoA aneurysm may also be considered as a cause of sudden unilateral ONP in patients with SAH.

• Korean Journal of Chemical Engineering
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• v.35 no.12
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• pp.2452-2463
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• 2018

Surface treatment of sol-gel bioglass is required to increase its biomedical applications. In this study, a dielectric barrier discharge (DBD) plasma treatment in atmospheric pressure was performed on the surface of [$SiO_2-CaO-P_2O_5-B_2O_3$] sol-gel derived glass. The obtained bioglass was treated by plasma using discharge current 12 mA with an exposure period for 30 min. The type of discharge can be characterized by measuring the discharge current and applied potential waveform and the power dissipation. Apatite formation on the surface of the DBD-treated and untreated samples after soaking in simulated body fluid (SBF) at $37^{\circ}C$ is characterized by Fourier transform infrared spectroscopy (FTIR), X-Ray diffraction (XRD), inductively coupled plasma (ICP-OES) and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS). We observed a marked increase in the amount of apatite deposited on the surface of the treated plasma samples than those of the untreated ones, indicating that DBD plasma treatment is an efficient method and capable of modifying the surface of glass beside effectively transforming it into highly bioactive materials.

• Journal of the Korean institute of surface engineering
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• v.49 no.1
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• pp.98-103
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• 2016

The dry etching characteristics of SnO thin films were investigated using inductively coupled plasma (ICP) in Ar, $CF_4$, $Cl_2$ chemistries. the SnO thin films were deposited by reactive rf magnetron sputtering with Sn metal target. In order to study the etching rates of SnO, the processing factors of processing pressure, source power, bias power, and etching gas were controlled. The etching behavior of SnO films under various conditions was obtained and discussed by comparing to that of $SiO_2$ films. In our results, the etch rate of SnO film was obtained as 94nm/min. The etch rates were mainly affected by physical etching and the contribution of chemical etching to SnO films appeared relatively week.

• Korean Journal of Materials Research
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• v.31 no.3
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• pp.162-171
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• 2021

Dry etching of copper thin films is performed using high density plasma of ethylenediamine (EDA)/hexafluoroisopropanol (HFIP)/Ar gas mixture. The etch rates, etch selectivities and etch profiles of the copper thin films are improved by adding HFIP to EDA/Ar gas. As the EDA/HFIP concentration in EDA/HFIP/Ar increases, the etch rate of copper thin films decreases, whereas the etch profile is improved. In the EDA/HFIP/Ar gas mixture, the optimal ratio of EDA to HFIP is investigated. In addition, the etch parameters including ICP source power, dc-bias voltage, process pressure are varied to examine the etch characteristics. Optical emission spectroscopy results show that among all species, [CH], [CN] and [H] are the main species in the EDA/HFIP/Ar plasma. The X-ray photoelectron spectroscopy results indicate the formation of CuCN compound and C-N-H-containing polymers during the etching process, leading to a good etch profile. Finally, anisotropic etch profiles of the copper thin films patterned with 150 nm scale are obtained in EDA/HFIP/Ar gas mixture.

• Particle and aerosol research
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• v.11 no.4
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• pp.107-113
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• 2015

SBA-16 (Santa Barbara Amorphous) was synthesized over supported $TiCl_4/MgCl_2$. Due to its high surface area and excellent morphological performance, it was expected to form the bi-supported catalytic system and be used for ethylene polymerization. Polymerization of ethylene was carried out at atmospheric pressure using hexane as solvent and triethylaluminium as cocatalyst. ICP, FTIR, DSC, TG-DTA were used to characterize polyethylene and catalyst product. Optimum conditions for ethylene polymerization were found to be 100 mL hexane, Al/Ti molar ratio of 160 and 1 h polymerization at $60^{\circ}C$. The activity of 396.76 kg PE/mol Ti.h.atm was achieved. Melting point of the obtained polymer was in the range of $132-135^{\circ}C$ and the highest degree of crystallization was 46%.