• Journal of Astronomy and Space Sciences
• /
• v.12 no.1
• /
• pp.90-101
• /
• 1995

We determined three dimensional precise WGS 84 corrdinates of two points in Bohyunsan Optical Astronomy Observatory using the GPS. One of the two points is the center on the top of pier for 1.8m telescope, and the other one is placed on the hill beside the dome of 1.8m telescope. We performed the simultaneous GPS observation at the KAO GPS station and Bohyunsan Obervatory for 5 days from December 18 to 22, 1993. We employed three Trimble 4000SST receivers for these observations. The observed data were processed by TRIMVEC-PLUS software of Trimble with the MBPS method and the Triple Difference L1/L2 ION free technique. Through this research, we determined WGS 83 latitude, longitude and height of 1.8m telescope in Bohyunsan Optical Astronomy Observatory with the values of $36^{circ}9'53".1943N\pm0."0018,\;128^{circ}58'35".6829E\pm0."0029,\;1162.47m\pm0.04m$, respectively.

• Proceedings of the Korean Vacuum Society Conference
• /
• 1999.07a
• /
• pp.110-110
• /
• 1999

Polyvinylidenefluoride (PVDF) is most used in piezoelectric polymer industry. Electrode effect on the electrical properties of PVDF has been investigated. al has been used due to fair adhesion for PVDF. Work function of metal plays an important role on the electrical properties of ferroelectrics for top and /or bottom electrode. However, Al has much lower work function than Pt or Au and so leakage current of Al/PVDF/Al may be large. Pt or Au has not been used for electrode of PVDF system due to poor adhesion. PVDF irradiated by Ar+ ion beam with O2 environment takes good adhesion to inert metal. Contact angle of PVDF to triple distilled water was reduced from 75$^{\circ}$ to 31$^{\circ}$ at 1$\times$1015 Ar+/cm2. Working pressure was 2.3$\times$10-4 Torr and base pressure was 5$\times$10-6 Torr. Pt was deposited by ion beam sputtering and thickness of pt film was about 1000$\AA$. in previous study, enhancing adhesion of Pt on PVDF was shown. in this study, effect of electrode on PVDF will be represented.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2000.11a
• /
• pp.21-24
• /
• 2000

Ferroelectric YMnO$_3$ thin films are excellent dielectric materials for high integrated ferroelectric random access memory (FRAM) with metal-ferroelectric-silicon field effect transistor (MFSFET) structure. In this study, YMnO$_3$ thin films were etched with C1$_2$/Ar gas chemistries in inductively coupled plasma (ICP). The maximum etch rate of YMnO$_3$ thin films is 285 $\AA$/min under C1$_2$/Ar of 10/0, 600 W/-200 V and 15 mTorr. The selectivities of YMnO$_3$ over CeO$_2$ and $Y_2$O$_3$ are 2.85, 1.72, respectively. The results of x-ray photoelectron spectroscopy (XPS) reflect that Y is removed dominantly by chemical reaction between Y and Cl, while Mn is removed more effective by Ar ion bombardment than chemical reaction. The results of secondary ion mass spectrometer (SIMS) were equal to these of XPS. The etch profile of the etched YMnO$_3$ film is approximately 65$^{\circ}$and free of residues at the sidewall.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.6 no.3
• /
• pp.431-438
• /
• 1996

Transmission electron microscopy has been used to investigate the microstructure of hot-pressed $TiB_{2}$. Thin foil specimens, prepared by conventional ion beam thinning, revealed many features which originated from the crystallographic anisotropy of hexagonal $TiB_{2}$. It was observed that in these specimens Fe-impurities are precipitated to form secondary Fe-rich phases at grain triple edges, in grain boundaries and sometimes in-grain. These Fe-rich precipitates were characterised by their coherence or semi-coherence to a favourably oriented grain at a grain triple edge or grain boundaries or to the matrix $TiB_{2}$ phase.

• Mass Spectrometry Letters
• /
• v.12 no.4
• /
• pp.126-130
• /
• 2021

The mass spectrometry (MS) provides the mass-to-charge ratios of atoms, molecules, stable/metastable complexes, and their fragments. I have taken a long journey with MS to address outstanding issues and problems by experiments and theory and gain insights into underlying principles in chemistry. By looking through the mass-to-charge ratio, I have studied thermochemical problems in silicon chemistry, the infrared multiphoton dissociation spectroscopy of organometallic intermediates, unimolecular dissociations of halotoluene radical cations, and the kinetics of association/dissociation of alkali halide triple ions with Lewis bases. Various MS platforms have been used to characterize non-covalent interactions between porphyrins and fullerenes and those between the group IIB ions and trioctylchalcogenides, and to examine the binding of the group IA, IIA and porphyrin ions to G-quadruplex DNA. Recently, I have focused on mass-balanced H/D isotope dipeptide tags for MS-based quantitative proteomics, a simple chemical modification method for MS-based lipase assay, and the kinetics and dynamics of energy-variable collision-induced dissociation of chemically modified peptides. Now, I see an important role of MS in global issues in the post-COVID era, as the society demands high standards for indoor air quality to contain the airborne-pathogen transmission as well as in-situ monitoring and tracking of carbon emissions to reduce global warming.

• Korean Journal of Environmental Agriculture
• /
• v.34 no.3
• /
• pp.230-237
• /
• 2015

BACKGROUND: To identify the sources of inaccuracy in LC/MS/MS methods used in the routine quantitation of small molecules are described and discussed. METHODS AND RESULTS: Various UPLC coupled to triple quadrupole mass spectrometer and time of flight (TOF) were used to identify the potential sources of inaccuracy and inducing the pitfalls of qualification and quntitation during the veterinary drug residue analysis. Some of stable isotope labelled veterinary drugs, which were used as internal standards, presented "cross-talk", regardless of manufactures of mass spectrometer and types of spectrometer. Group of sulfonamides also presented inaccuracy qualification and quantitation due to the multi-residue analytical method with the same fragment ions at the close retention times. CONCLUSION: The phenomena of "cross-talk" occurring between subsequently monitored transition from stable isotope labelled and isotope non-labelled authentic chemical were identified. To prevent errors and achieve more accurate data during the analysis of small molecules by LC/MS/MS SRM method, Followings should be taken care of and kept checking; purity and concentration of stable isotope as an internal standard, prevention of carry-over during the separation in column, minimizing the ion suppression by matrix effect, identification of retention time, precursor ion and product ion, and full knowledge of data processing including smoothing and peak integration.

• Analytical Science and Technology
• /
• v.14 no.6
• /
• pp.486-493
• /
• 2001

The effect of SIMS analysis conditions such as mesh grid, offset voltage and ion species on the in-depth profile for bismuth titanate thin film was examined in terms of charging effect and detection limit. The results shows that the use of offset voltage -40 V reduces the charging effect and the detection limit. The employment of mesh grid in sample preparation leads to the reduction of the charging effect in small amount, but deteriorate the detection limit. Utilization of primary $O^-$ ion for SIMS analysis of bismuth titanate thin film showed almost the same effect as using offset voltage -40 V. However, it takes approximately triple acquisition time than using $O_2{^+}$ ion due to the poor beam current of the source in the experiment.

• Journal of the Korean Magnetic Resonance Society
• /
• v.10 no.2
• /
• pp.155-162
• /
• 2006

Angiogenin is unique among angiogenic molecules in that it is a member of the pancreatic ribonuclease superfamily and, in fact, is a ribonucleolytic enzyme. Its enzymatic activity is extremely weak compared to that of the digestive RNases but is critical for its capacity to induce neovascularization. In this study, we completed the backbone resonance assignment of bovine angiogenin using triple resonance NMR experiments of $^{15}N\;and/or\;^{13}C$ isotope labeled protein and investigated the chemical shift variation upon binding with inhibitor phosphate ion and determine the phosphate binding site.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2008.11a
• /
• pp.9-10
• /
• 2008

Triple layers structure of $SiO_2$/ZnS:Mn/ZnS was synthesized by using ion substitution and chemical precipitation method. Each layer thickness was controlled by adjusting the concentration of manganese (II) acetate ($Mn(CH_3COO)_2$) and tetraethyl orthosilicate (TEOS). The structure and morphology of prepared phosphors were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron probe microscopic analyzer (EPMA). Photoluminescence (PL) properties of ZnS with different layer thickness and amount of Mn activator were analyzed by PL spectrometer. PL emission intensity and PL stability were analyzed for evaluating effects of Mn activator.

• Bulletin of the Korean Chemical Society
• /
• v.2 no.3
• /
• pp.90-96
• /
• 1981

The significant structure theory of liquids has been successfully applied to the sodium ammonia solution. In applying the theory to sodium ammonia solution, we assumed there were four species in solution, i.e., sodium cation, solvated electron, triple ion, and free electron and equilibria existed between them. Based on these assumptions, we set up the model explaining the anomalous properties of sodium ammonia solution. The partition function for sodium ammonia solution is composed of the partition functions for the above four species and also for the Debye-Huckel excess free energy term. Agreements between calculated and experimental values of the thermodynamic quantities, such as molar volume, vapor pressure, partial molar enthalpy and entropy, and chemical potential as well as viscosity are quite satisfactory.