• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.145-145
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• 2000

M-CeO2 (M : noble metal) catalysts have been widely studied as three-way catalysts and methanol synthesis catalysts. Ceria is thought to play a number of roles in these catalysts. The Ce(IV)/Ce(III) redox pair may store/release gases under oxidizing/reducing conditions, extending the operational window. Additionally, metal-ceria interactions lead to several effects, including the dispersion of the active components and promoting the activation of molecules such as CO or NO. Pd is a promising component to current TWC formulations and behaves particularly well when compared with Pt and Rh-based catalysts for low-temperature oxidation of Co and hydrocarbon. However the effect of Pd-ceria interactions on the physicochemical properties of Pd and the redox properties of Ce is not elucidated yet. In order to know exactly about the metal-ceria interactions, the model study are expecting to give a better environment, resulting in the wide use of the surface science tools. The substrate was Si(100) wafer, on which Ta metal was sputtered as a thickness of 100nm. The CeO2 thin film of 30nm was deposited by using the magnetron sputtering. Spin coating and magnetron sputtering methods were used to make the Pd thin film layer. The prepared sample was investigated by in-situ XPS, AES, SEM and AFM analysis.

• Bulletin of the Korean Chemical Society
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• v.15 no.9
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• pp.752-758
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• 1994

Several one-electron reduction products of ${\gamma}$(1,2)-[$H_nSiV_2W_{10}O_{40}]^{(6-n)-}$ were separated by precipitating or coprecipitating with diamagnetic host compounds at different pH. Mono-and diprotonated species, 1 and 2, in powder samples exhibit aPR spectra characteristic of a mononuclear oxovanadium species, indicating that the unpaired electron is trapped at one vanadium atom. The EPR spectrum of the unprotonated species 0 shows 15 parallel lines, indicating that the unpaired electron interacts equally with two vanadium atoms. While different species were precipitated depending upon the pH of the solution and the charge of the host anion, only one species 1' was formed in the frozen solutions at pH 3.2-4.7. The EPR spectrum of 1' indicates that the unpaired electron is trapped at one vanadium atom and 1/16 of the spin density is delocalized onto the second vanadium atom. The species 1' is probably another form of the monoprotonated species. The EPR spectra show that some of 2 transform into 1 and some of 0 transform into 1' in the solid state at low temperatures. It is suggested that proton transfer between the heteropolyanion and water molecues in the solid state is involved in these transformations.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.23 no.6
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• pp.87-107
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• 2020

The purpose of this study is to present the basic data for maintenance and management of river ecosystem by surveying and analysing the kinds and their characteristics of vascular plants in Bukcheon stream, Gyeongju-si, South Korea. The numbers of vascular plants were summarized as 428 taxa including 92 families, 265 genera, 3 subspecies, 24 varieties, 6 forms, 5 hybrids and 5 cultivars. Among the identified taxa, there were 90 planted species. The endangered wild species was Cicuta virosa, and the rare plants were 5 taxa including Prunus × yedoensis, Juniperus chinensis L. var. sargentii and so on. The Korean endemic plants were 5 taxa Populus × tomentiglandulosa, Salix koriyanagi, Lespedeza maritima, Forsythia koreana and Aster pseudoglehni. The specific plants by floristic region were 26 taxa including 2 taxa of grade V, 3 taxa of grade IV, 2 taxa of grade III, 8 taxa of grade II and 11 taxa of grade I. The naturalized plants were 81 taxa including Euphorbia maculata, Erigeron strigosus, Vulpia myuros and so on. The invasive alien plants were 7 taxa including Humulus scandens, Rumex acetosella, Ambrosia artemisiifolia, Ambrosia trifida, Lactuca seriola, Symphyotrichum pilosum and Paspalum distichum.

• Journal of Chest Surgery
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• v.39 no.3 s.260
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• pp.194-200
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• 2006

Background: Thoracoabdominal aortic replacement is an extensive operation that opens both the pleural cavity and abdominal cavity, which has high mortality and morbidity rate. The authors have reported 9 cases of the thoracoabdominal aortic replacement in 2001. Since 2003 we have applied the deep hypothermic circulatory arrest to the Crawford type I and II thoracoabdominal aortic replacement. Therefore, we analysed the effect of the changes in operative techniques. Material and Method: Between 1996 and 2005, we have performed 20 cases of thoracoabdominal aortic replacement. The underlying diseases were 8 cases of atherosclerotic aneurysm with 4 cases of ruptured aneurysm and 12 cases of aortic dissection with 10 cases of a previous operations. According to Crawford classification, there were 2 cases of type I, 7 cases of type II, 1 case of type III, 7 cases of type IV, and 3 cases of type V. We compaired the results of the patients who underwent thoracoabdmoninal replacement before 2001 which already has been reported and after then. Result: Before 2001 we have performed 9 cases of thoracoabdominal replacement and 5 patients were died of the operation. All three patients with type I and II were died. There was no case of thoracoabdominal replacement between 2001 and 2002, but after 2003 we have performed 11 cases of thoracoabdominal replacement which involved 1 case of type I, 5 cases of type II, 1 case of type III, 2 cases of type IV and 2 cases of type V. There was no mortality and no fetal complications. Conclusion: The deep hypothermic circulatory arrest is a safe method of extended thoracoabdominal aortic replacement.

• Economic and Environmental Geology
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• v.24 no.1
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• pp.1-8
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• 1991

North ore deposits of the Dunjeon gold mine is disseminated-stockworks deposits emplaced in Ordovician Dongjeom quartzite. Six types of fluid inclusions are recongnized in the stage I quartz. Among them polyphase inclusions(type-IV-A, B) are predominent in the lower part of stage I quartz crystals whereas liquid and gas inclusions(type I, II) are abundant in the upper part of the same quartz crystals. Liquid $CO_2$-bearing inclusions(type III-A, B)occur as pseudosecondary inclusions. Solid phases in polyphase inclusions are identified by using scanning electron microscopy combined with energy dispersive x-ray spectroscopy. The solid phases are as follows; halite, sylvite, hydrophyllite, quartz, muscovite, calcite, ankerite, K-Mg-Fe-Al-Si mineral, Ca-Fe-Si mineral, Mg-Al-Si mineral, two kinds of Fe-mineral and Cu-Fe mineral. Results of freezing and heating experiments of fluid inclusions and identification of daughter minerals in polyphase inclusions in the stage I quartz reveal that ore fluids were high saline system NaCl-KCl-$CaCl_2$-$H_2O$ in the earier stage and then evolved to rather simple system NaCl-$H_2O$ in the later stage, and temporally fluid mixing occured with system $CO_2$-$H_2O$. Homogenization temperatures and salinity of fluid inclusions in the stage I range from 290 to $454^{\circ}C$ and from 0.2 to 54.2 wt. % equivalent to NaCl.

• KSTLE International Journal
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• v.2 no.2
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• pp.120-126
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• 2001

Performance requirements for automatic transmission fluids have been changed reflecting the design changes of automatic transmissions. The major purpose of these design changes is concentrated upon improvements of both fuel economy and drivability. In order to formulate such high performance ATFs as satisfy those requirements, it is necessary to use high quality base oils like VHVI base oils and PAOs. In this study, the effect of base oils characteristics on ATF performance is investigated, mainly regarding differences in frictional characteristics with deterioration. Frictional characteristics are determined using the SAE No. 2 machine and ATFs are deteriorated under various controlled conditions. Moreover low-temperature fluidity, oxidation stability, and seal compatibility are also compared for four different ATFs. From the investigation, it was found that the use of Group III and IV base oils in ATFs gives several benefits with respect to low temperature viscosity, oxidation stability and SAE No.2 friction characteristics.

• Korean Journal of Head & Neck Oncology
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• v.26 no.2
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• pp.221-224
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• 2010

Papillary thyroid carcinoma frequently invades the lymph node, trachea, esophagus and perithyroid tissue. However, direct extension to posterior pharyngeal area is known to be rare. A 64-year-old male was referred to our clinic presenting as posterior pharyngeal mass during gastrofiberscopy. The neck CT scan showed soft tissue mass in retropharynx and lymph node in right level III with calcifications. We performed the total thyroidectomy with selective(level II, III, IV) and anterior compartment neck dissection. In operative findings, the right thyroid mass were connected to the retropharynx through the posterior portion of inferior constrictor muscle. Histopathologic findings revealed the papillary thyroid carcinoma extended to retropharynx. We report a unique case with a literature review.

• Journal of Astronomy and Space Sciences
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• v.11 no.1
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• pp.31-40
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• 1994

The IUE low dispersion spectra of AZ Cas have been analyzed for line identifications and energy distribution in ultraviolet region. Highly ionized atoms, SiIV and CIV are identified. We could infer a temperature range of the B star between 15,000K and 20,000K. The energy density distribution shows a hump between IUE short wavelength and long wavelength regions. Photometric and spectroscopic elements were revised based on the Florkowisk photeelectric observations and collected radial velocities. The temperature of both stars were reduced as 16,000K and 3,800K. The radii of both stars are $10 R_{\odot}\;and\;320R_{\odot}$. The eccentricity and longitude of periastron are 0.61 and $10.5^{\circ}$, respectively.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.81.4-82
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• 2017

We investigate velocity oscillations in the active region plage by using the high-spatial, high-spectral and high-temporal resolution spectral data acquired by the Interface Region Imaging Spectrograph (IRIS). From the Mn I $2801.907{\AA}$ (lower chromosphere), C II (lower transition region) and Si IV (middle transition region) lines, we measure the line of sight Doppler velocity at different atmospheric layers, and present results of wavelet analysis of the plage region with a range of periods from 2 to 8 minutes. In addition, we present correlations of the oscillations from the lower chromosphere to the middle transition region. Finally, we will discuss the regional dependence of the oscillation properties on physical properties such as temperature and magnetic field inclination.

• Korean Journal of Pharmacognosy
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• v.25 no.4 s.99
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• pp.328-335
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• 1994

The ether soluble fraction of the methanol extract from the fruits of Crataegus pinnatifida var. psilosa was applied to silica gel column chromatography, eluted step-gradiently with a mixture of dichloromethane and methanol, repeatedly, and five compounds were isolated. These compounds are identified as ursolic acid(I), corosolic acid(II) and euscapic acid (III), ${\beta}-sitosteryl-3-O-{\beta}-_D-glucopyranoside(IV)$ and hyperin(V).