• Journal of the Korean earth science society
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• v.29 no.1
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• pp.29-44
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• 2008

This study investigates the influence of the developing and decaying El $Ni{\tilde{n}}o$-Southern Oscillation (ENSO) on the relation between typhoon intensity and its formation. From the long-tenn data of 57 years ($1950{\sim}2006$), we first defined the developing El $Ni{\tilde{n}}o$ years and the neutral years. During the developing El Nino years, the typhoon intensity has a strong relationship with formation region of the tropical cyclone, which results in an increase of the accumulated cyclone energy and intensity of energy of typhoon. During the developing El $Ni{\tilde{n}}o$ year based on $Ni{\tilde{n}}o$ 3.4 SST, the locations for the formation of the category 4+5 typhoon move to the eastward region. The genesis potential function and the low-level cyclonic vorticity have an important role on the formation of strong tropical cyclones, which eventually develop as a typhoon class. In this study, the dynamic potential (DP) function (Gray, 1977) and EOF 1 and EOF 2 time series (RMM 1 and RMM 2) of real-time multivariate MJO (Wheeler and Hendon, 2004) are used to measure the genesis potential and the low-level cyclonic vorticity, respectively. To investigate the influence of the developing and decaying ENSO, we defined the Type I case of the decaying El $Ni{\tilde{n}}o$ that turnovers to La Nina, and the Type II case of the recovering years to the neutral condition. During the decaying El $Ni{\tilde{n}}o$ years as Type I, the locations of the strong DP, RMM 1 and RMM 2 move to the westward more prominently to induce retard of the strong typhoon developing.

• Journal of the Korean earth science society
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• v.33 no.1
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• pp.1-10
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• 2012

Analysis on high-resolution seismic and core data reveals that the sedimentary strata in Gyeonggi Bay consists of four sedimentary units (Unit I-IV, from top to bottom) formed during the late Quaternary period. Unit I is interpreted as sediments of tidal flat and channel-fill deposits, formed during the Holocene transgression. Unit II is divided into shallow-marine facies unit in offshore area and channelized fluvial to estuarine facies unit in nearshore sand ridge and tidal flat. Unit III is considered as tidal flat deposits with the uppermost severely weathered and oxydized layers. This unit is composed of shallow marine sedimentary successions formed during the MIS-5 highstand. The lowermost Unit IV rests on Mesozoic basement rocks, considered as the shallow marine and shelf deposits formed before the MIS-5 lowstand.

• Journal of the Korean earth science society
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• v.33 no.6
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• pp.534-543
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• 2012

The relationship between tectonic uplift and geophysical analysis of gravity anomalies and the in-situ stress fields in the Otway Ranges, SE Australia is addressed in this study to understand the nature and possible mechanism for the neotectonic movements. The uplift axis of the ranges is coincident with the regional Bouguer gravity highs whereas thick Tertiary sedimentary successions are highly correlated with the gravity lows along the basin rift geometry. This result suggests that the gravity highs are separated by the thick Tertiary sedimentary successions. Regional structural trends associated with faults and foldings of the deformed surfaces are consistent with the prevailing NW-SE $S_{Hmax}$ trend in this part of the continent. The anomalously positive correlation between topography and Bouguer gravity fields suggests possibly a lithospheric flexural deformation mode at a long wavelength (order of $10^2$ kms) in the region. It also suggests that the reactivation of pre-existing lithospheric structures driven by plate boundary forces plays a key role in this mode.

• Bulletin of the Korean Chemical Society
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• v.23 no.10
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• pp.1394-1398
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• 2002

A novel copper(II) membrane electrode based on diphenylisocyanate bis(acetylacetone) ethylenediimine (DIBAE), as a new hexadentates Schiff's base was prepared. The electrode exhibited a Nernstian response for Cu$^{2+}$ ions over a wide concentration range (1.0 ${\times}$ 10$^{-1}$ to 1.0 ${\times}$ l0$^{-6}$ M) with a limit of detection of 6.0 ${\times}$ 10$^{-7}$ M (39 ppb). The sensor shows a fast response time (15s) and the membrane can be used for more than 4 months without observing any major deviation. The electrode revealed very good selectivity with respect to many cations including alkali, alkaline earth, transition and heavy metal ions. The proposed sensor could be used in a pH range of 3.0-7.5. It was applied to the direct potentiometric determination of copper in black tea, and in wastewater of copper electroplating samples. The electrode was also used in potentiometric titration of the copper(II) ion with EDTA.

• Journal of Astronomy and Space Sciences
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• v.30 no.4
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• pp.269-277
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• 2013

In this study, we present results of precise orbital geodetic parameter estimation using satellite laser ranging (SLR) observations for the International Laser Ranging Service (ILRS) associate analysis center (AAC). Using normal point observations of LAGEOS-1, LAGEOS-2, ETALON-1, and ETALON-2 in SLR consolidated laser ranging data format, the NASA/GSFC GEODYN II and SOLVE software programs were utilized for precise orbit determination (POD) and finding solutions of a terrestrial reference frame (TRF) and Earth orientation parameters (EOPs). For POD, a weekly-based orbit determination strategy was employed to process SLR observations taken from 20 weeks in 2013. For solutions of TRF and EOPs, loosely constrained scheme was used to integrate POD results of four geodetic SLR satellites. The coordinates of 11 ILRS core sites were determined and daily polar motion and polar motion rates were estimated. The root mean square (RMS) value of post-fit residuals was used for orbit quality assessment, and both the stability of TRF and the precision of EOPs by external comparison were analyzed for verification of our solutions. Results of post-fit residuals show that the RMS of the orbits of LAGEOS-1 and LAGEOS-2 are 1.20 and 1.12 cm, and those of ETALON-1 and ETALON-2 are 1.02 and 1.11 cm, respectively. The stability analysis of TRF shows that the mean value of 3D stability of the coordinates of 11 ILRS core sites is 7.0 mm. An external comparison, with respect to International Earth rotation and Reference systems Service (IERS) 08 C04 results, shows that standard deviations of polar motion $X_P$ and $Y_P$ are 0.754 milliarcseconds (mas) and 0.576 mas, respectively. Our results of precise orbital and geodetic parameter estimation are reasonable and help advance research at ILRS AAC.

• Journal of The Korean Astronomical Society
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• v.32 no.2
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• pp.109-117
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• 1999

UBVI CCD photometry has been obtained for a region around the Wolf-Rayet star WR 12. We found two young stellar associations in the observed field: the nearer one comprises the field members of Vela OBI association at d = 1.8kpc, while the farther one is the young open cluster Bochum 7 (Bo 7) at d = 4.8kpc. The stars associated with Bo 7 showed no central concentration which suggests that Bo 7 is not a young open cluster but simply a local concentration in the density of young stars belonging to the OB association (Vel OB3). These two associations have similar ages but remarkably different mass function slopes ($\Gamma$ = -2.1 $\pm$ 0.3 for Vel OBI and -1.0 $\pm$ 0.3 for Bo 7). The stars in Vel OBI shows an evident age spread (${\Delta}T\~ 9Myr$). We also found two strong H$\alpha$ emission stars - WR 12 and $\sharp$1066 - from narrow band H$\alpha$ photometry.

• Journal of The Korean Astronomical Society
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• v.53 no.2
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• pp.35-42
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• 2020

We analyze high dispersion emission lines of the symbiotic nova AG Pegasi, observed in 1998, 2001, and 2002. The Hα and Hβ lines show three components, two narrow and one underlying broad line components, but most other lines, such as H_I, He_I, and He_II lines, show two blue- and red-shifted components only. A recent study by Lee & Hyung (2018) suggested that the double Gaussian lines emitted from a bipolar conical shell are likely to form Raman scattering lines observed in 1998. In this study, we show that the bipolar cone with an opening angle of 74°, which expands at a velocity of 70 km s^-1 along the polar axis of the white dwarf, can accommodate the observed double line profiles in 1998, 2001, and 2002. We conclude that the emission zone of the bipolar conical shell, which formed along the bipolar axis of the white dwarf due to the collimation by the accretion disk, is responsible for the double Gaussian profiles.

• Journal of the Korean earth science society
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• v.23 no.1
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• pp.72-86
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• 2002

The Middle to Late Cambrian Machari Formation in the Machari area, Yeongweol, Korea consists of 7 lithofacies and 3 facies associations, which are thought to be deposits of carbonate ramp (mid to outer ramp) to basin environment. These lithofacies are bedded lime mudstone, laminated lime mudstone, bioclastic/peloidal packstone to grainstone, poloidal/bioclastic wackestone, conglomerate, mottled lime mudstone, and shale. Bedded lime mudstone facies, a few cm thick lime mudstone alternating with shale layer, is believed to have been deposited by intermittent dilute turbidity currents. Laminated lime mudstone facies, alternating lime mudstone with laminated shale, is interpreted to have been formed by fine-grained turbidity currents. Bioclastic/peloidal packstone to grainstone facies was deposited by turbidity current and peloidal/bioclastic wackestone faceis was deposited by debris flow. Conglomerate facies is thought to be deposits of storm activities. Mottled lime mudstone facies is interpreted to have been formed by bioturbation. Shale facies is interpreted to have been formed by suspension settling. Seven lithofacies of the Machari Formation are divided into three facies associations. Facies association I consisted of bedded lime mudstone facies, mottled lime mudstone facies, conglomerate facies, and bioclastic/peloidal packstone to grainstone facies, is interpreted to have been deposited on the mid ramp. Facies assocaition II consisted of bedded lime mudstone facies, laminated lime mudstone facies, bioclastic/peloidal packstone to grainstone facies, and peloidal/bioclastic wackestone facies is thought to be deposits of the outer ramp. Facies association III consisted of laminated lime mudstone facies and shale facies is interpreted to have been formed on the basin environment.

• Journal of The Korean Astronomical Society
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• v.34 no.2
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• pp.67-80
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• 2001

Chemical evolution of galaxies can be understood by studying the spatial distribution of heavy elements. We selected two nearby galaxies, M31 and M33 and investigated spectrum of their HII regions: a) the elec-tron densities have been derived from the [S II] 6717/6731 ratio along with the most recent atomic constants (Hyung & Aller 1996); b) the electron temperatures were determinated from the Pagel's empirical method. Nebula Model (Hyung 1994) has been employed to predict the spectral line intensities which gives the proper chemical abundances. The model would predict the line intensities correctly only when various input parameters such as the effective central star temperatures, gravity log g, model atmosphere as well as the geometry and the nebula physical condition are appropriate. Thus, the determination of chemical abundances of O, S, N of the two nearby galaxies M31 and M33 has been done, which shows a radial dependance of O/H and N/H: decrease with the distance, or increasing electron temperature due to the elemental deficiency. Abundances of M31 appear to be enhanced than those of M33.

• Korean Journal of Remote Sensing
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• v.25 no.3
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• pp.215-223
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• 2009

The noise removal as a preprocessing was tried with various kinds of wavelet pairs. Wavelet transform for 2D images generally uses the same wavelets as basis functions in horizontal and vertical directions. A method with different wavelets was tried for each direction separately, which gives more precise interpretation of the classification. Total 486 pairs of wavelets from nine basis functions were tried to remove image noises. The classification accuracies before and after the noise removal were compared. Although all kinds of wavelet pairs showed the increased accuracies in classification, there were best and worst wavelet pairs depending on the data sets. Wavelet pairs with low energy percentage of LL band showed the high classification accuracy. A pattern was found in the results that very similar vertical accuracy was distributed for each horizontal ones. Since Haar is the shortest length filter, Haar could be a predictor wavelet to find the good wavelet pairs.