• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.7
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• pp.770-778
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• 2023

Sea surface wind is an important variable for elucidating the atmospheric-ocean interactions and predicting the dangerous weather conditions caused by oceans. Accurate sea surface wind data are required for making correct predictions; however, there are limited observational datasets for oceans. Therefore, this study aimed to obtain long-period high-resolution sea surface wind data. First, the ERA5 reanalysis wind field, which can be used for a long period at a high resolution, was regridded and synthesized using the asymmetric typhoon wind field calculated via the Generalized Asymmetric Holland Model of the numerical model named ADvanced CIRCulation model. The accuracy of the asymmetric typhoon synthesized wind field was evaluated using data obtained from Korea Meteorological Administration and Japan Meteorological Administration. As a result of the evaluation, it was found that the asymmetric typhoon synthetic wind field reproduce observations relatively well, compared with ERA5 reanalysis wind field and symmetric typhoon synthetic wind field calculated by the Holland model. The sea surface wind data produced in this study are expected to be useful for obtaining storm surge data and conducting frequency analysis of storm surges and sea surface winds in the future.

• Korean Journal of Remote Sensing
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• v.38 no.6_1
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• pp.1069-1080
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• 2022

The tropospheric ozone is a pollutant that causes a great deal of damage to humans and ecosystems worldwide. In the event that ozone moves downwind from its source, a localized problem becomes a regional and global problem. To enhance ozone monitoring efficiency, geostationary satellites with continuous diurnal observations have been developed. The objective of this study is to derive the Tropospheric Ozone Movement Vector (TOMV) by employing continuous observations of tropospheric ozone from geostationary satellites for the first time in the world. In the absence of Geostationary Environmental Monitoring Satellite (GEMS) tropospheric ozone observation data, the GEOS-Chem model calculated values were used as synthetic data. Comparing TOMV with GEOS-Chem, the TOMV algorithm overestimated wind speed, but it correctly calculated wind direction represented by pollution movement. The ozone influx can also be calculated using the calculated ozone movement speed and direction multiplied by the observed ozone concentration. As an alternative to a backward trajectory method, this approach will provide better forecasting and analysis by monitoring tropospheric ozone inflow characteristics on a continuous basis. However, if the boundary of the ozone distribution is unclear, motion detection may not be accurate. In spite of this, the TOMV method may prove useful for monitoring and forecasting pollution based on geostationary environmental satellites in the future.

• Korean Journal of Remote Sensing
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• v.36 no.2_2
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• pp.351-363
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• 2020

It is well known that alluvial sediment located in coastal region has been easily affected by geohazard like ground subsidence, marine or meteorological disasters which threaten invaluable lives and properties. The subsidence is a sinking of the ground due to underground material movement that mostly related to soil compaction by water extraction. Thus, continuous monitoring is essential to protect possible damage from the ground subsidence in the coastal region. Radar interferometric application has been widely used to estimate surface displacement from phase information of synthetic aperture radar (SAR). Thanks to advanced SAR technique like the Small BAseline Subset (SBAS), a time-series of surface displacement could be successfully calculated with a large amount of SAR observations (>20). Because the ALOS-2 PALSAR-2 L-band observations maintain higher coherence compared with other shorter wavelength like X- or C-band, it has been regarded as one of the best resources for Earth science. However, the number of ALOS-2 PALSAR-2 observations might be not enough for the SBAS application due to its global monitoring observation scenario. Unfortunately, the number of the ALOS-2 PALSAR-2 Stripmap images in area of our interest, Busan which located in the Southeastern Korea, is only 11 which is insufficient to apply the SBAS time-series analysis. Although it is common that the radar interferometry utilizes multiple SAR images collected from same acquisition mode, it has been reported that the ALOS-2 PALSAR-2 Stripmap-ScanSAR interferometric application could be possible under specific acquisition mode. In case that we can apply the Stripmap-ScanSAR interferometry with the other 18 ScanSAR observations over Busan, an enhanced time-series surface displacement with better temporal resolution could be estimated. In this study, we evaluated feasibility of the ALOS-2 PALSAR-2 Stripmap-ScanSAR interferometric application using Gamma software considering differences of chirp bandwidth and pulse repetition frequency (PRF) between two acquisition modes. In addition, we analyzed the interferograms with respect to spectral shift of radar carrier frequency and common band filtering. Even though it shows similar level of coherence regardless of spectral shift in the radar carrier frequency, we found periodic spectral noises in azimuth direction and significant degradation of coherence in azimuth direction after common band filtering. Therefore, the characteristics of spectral bandwidth in the range and azimuth direction should be considered cautiously for the ALOS-2 PALSAR-2 Stripmap-ScanSAR interferometry.

• The Korean Journal of Applied Statistics
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• v.24 no.6
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• pp.1129-1138
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• 2011

Small area estimation has received significant intention in recent years due to a growing demand for reliable local area statistics. Traditional area-specific direct estimates based solely on sample survey data in the areas of interest do not provide adequate small area precision; however, design-based indirect local area estimators borrow strength from sample observations of related areas to increase the effective sample size. Design-based indirect estimation methods such as synthetic and composite estimators are considered to adjust local area unemployment rate estimates in the Korean Economically Active Population Survey. This study suggests an efficient alternative to minimize the cost to construct the unemployment rate of a local area through simulation under the condition that we can maintain a certain level of CV for the estimates. We obtained the results that the composite estimators using a sample size greater than 10 are more stable and significant at the level of CV 25% in our design scheme.

• Journal of Chest Surgery
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• v.22 no.4
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• pp.525-547
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• 1989

Hemorrhagic tendency observed in open heart surgery patients has been attributed, among other causes, to increased fibrinolytic activity during extracorporeal circulation. But the exact mechanism of enhanced fibrinolytic activity which occurs during extracorporeal circulation is still unknown. So, we studied and compared the changes of parameters of fibrinolytic and protein C system according to time obtained from the plasma of 31 adult open heart surgery patients[EGG group] and 10 adult general thoracic surgery patients[control group], in order to confirm the hypothesis that the activated protein C system might affect the fibrinolytic system during extracorporeal circulation. In ECC group, the nature of the enhanced fibrinolytic activity that evolved during extracorporeal circulation was characterized by significant increase in fibrin degradation products[P < 0.01] and significant decrease in plasminogen and alpha2-antiplasmin[P < 0.05, P < 0.01] in spite of adequate amount of heparin administration. These changes were most pronounced in the early phase of extracorporeal circulation and normalized after termination of extracorporeal circulation. The results of these observations were the same after volume correction with the value of hematocrit. The change of volume corrected protein C ratio during extracorporeal circulation revealed similar pattern to those of plasminogen and alpha2-antiplasmin [P < 0.01], but volume corrected ratio of free protein S showed significant increase after the commencement of extracorporeal circulation then decreased after extracorporeal circulation. Although the above mentioned changes occur similarly in both bubble type oxygenator-used and membrane oxygenator-used patients groups, but the degree of decrease was more severe in membrane oxygenator-used patients group [P < 0.01] and showed much slower recovery to reach to the preextracorporeal circulation level. These results confirm the hypothesis that the enhanced fibrinolysis during extracorporeal circulation might be caused by the activation of protein C system and the activation is possibly linked to the appearance of thrombin from contact activation of blood after wide exposure to the synthetic surfaces of extracorporeal circuit. Key words: Extracorporeal circulation, Enhanced fibrinolysis, Protein C system.

• Korean Journal of Materials Research
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• v.18 no.11
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• pp.583-591
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• 2008

In this study, two series of CNT/$TiO_2$ electrodes were prepared. The decrease of surface area compared with that of the pristine carbon nanotubes (CNTs) indicated the blocking of micropores on the surface of the CNTs; was further supported by scanning electron microscopy (SEM) and field emission SEM (FE-SEM) observations. The X-ray diffraction (XRD) results showed that the CNT/$TiO_2$ composites contained a mix of anatase and rutile forms of $TiO_2$ particles when the precursor was $TiO_2$ powder, whereas when the precursor was Ti ($OC_4H_7$) (TNB), the composites contained only the typical single and clear anatase $TiO_2$ particles. The energy dispersive X-ray spectroscopy (EDX) spectra showed the presence of C, O and Ti peaks for all samples. It was found that catalytic decomposition of methylene blue (MB) solution could be attributed to synthetic effects between the $TiO_2$ photocatalysis and electro-assisted CNTs network, and that photoelectrocatalytic oxidation increased with an increase of CNT composition. It was also found that the photoelectrocatalytic oxidation efficiency for MB is higher than that of photocatalytic oxidation. Moreover, the CNT/$TiO_2$ composites catalyst prepared by the impregnation method demonstrates higher photoelectrocatalytic activity than the mechanical mixture with the same CNT content.

• The Journal of Engineering Geology
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• v.27 no.3
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• pp.305-312
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• 2017

The most effective way to distinguish subsurface interfaces that produce various geophysical responses is through the integration of multiple geophysical methods, with each method detecting both a complementary and unique set of distinct physical properties relating to the subsurface. In this study, shallow seismic reflection (SSR) and ground penetrating radar (GPR) surveys were conducted at the Cheongju-Gadeok site of the Korea National Groundwater Monitoring Network to map the water table, which was measured at 12 m depth during the geophysical surveys. The water table proved to be a good target reflector in both datasets, as the abrupt transition from the overlying unsaturated weathered rock to the underlying saturated weathered rock yielded large acoustic impedance and dielectric constant contrasts. The two datasets were depth converted and integrated into a single section, with the SSR and GPR surveys conducted to ensure subsurface imaging at approximately the same wavelength. The GPR data provided detailed information on the upper ~15 m of the section, whereas the SSR data imaged structures at depths of 10-45 m. The integrated section thus captured the full depth coverage of the sandy clay, water table, weathered rock, soft rock, and hard rock structures, which correlated well with local drillcore and water table observations. Incorporation of these two geophysical datasets yielded a synthetic section that resembled a simplified aquifer model, with the best-fitting seismic velocity, dielectric constant, and porosity of the saturated weathered layer being $v_{seismic}=1000m/s$, ${\varepsilon}_r=16$, and ${\phi}=0.32$, respectively.

• Journal of Microbiology and Biotechnology
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• v.10 no.5
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• pp.612-619
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• 2000

To investigate the biochemical properties of V. mimicus metalloprotease, whose gene was isolated previously from Vibrio mimicus ATCC33653, overexpression and purification were attempted. The 1.9 kb of open reading frame was amplified by PCR from pVMC193 plasmid which ligated the VMC gene with pUC19 and introduced into Escherichia coli BL21 (DE3) using the overexpression vector, pET22b (+). The overexpressed metalloprotease (VMC) was purified with Ni-NTA column chromatography and characterized with various protease inhibitors, pHs, temperatures, and substrates. The purified VMC showed the proteolytic activity against gelatin, soluble and insoluble collagens, and synthetic peptides. Unlike the observations made with all metalloproteases originated from other Vibrio sp., the VMC did not hydrolyze the casein. The proteolytic activity was critically decreased when the VMC was treated with metal chelating reagents, such as EDTA, 2,2-bipyridine, and 1, 10-phenanthroline. In particular, the 71 kDa VMC exhibited the hemagglutinating activity against human erythrocyte. As the purified VMC was treated with $CuCl_2$ and $NiCl_2$ for the chemical modification of metal binding, the proteolytic activity and hemagglutinating activity were profoundly influenced. The multialignment analysis made on the reported Vibrio metalloproteases showed the difference of amino acid sequence similarity between the two distinctive classes of Vibrio metalloproteases.

• Journal of Astronomy and Space Sciences
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• v.28 no.1
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• pp.55-62
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• 2011

The precise orbit determination (POD) of low earth orbiter (LEO) has complied with its required positioning accuracy by the double-differencing of observations between International GNSS Service (IGS) and LEO to eliminate the common clock error of the global positioning system (GPS) satellites and receiver. Using this method, we also have achieved the 1 m positioning accuracy of Korea Multi-Purpose Satellite (KOMPSAT)-2. However double-differencing POD has huge load of processing the global network of lots of ground stations because LEO turns around the Earth with rapid velocity. And both the centimeter accuracy and the near real time (NRT) processing have been needed in the LEO POD applications--atmospheric sounding or urgent image processing--as well as the surveying. An alternative to differential GPS for high accuracy NRT POD is precise point positioning (PPP) to use measurements from one satellite receiver only, to replace the broadcast navigation message with precise post processed values from IGS, and to have phase measurements of dual frequency GPS receiver. PPP can obtain positioning accuracy comparable to that of differential positioning. KOMPSAT-5 has a precise dual frequency GPS flight receiver (integrated GPS and occultation receiver, IGOR) to satisfy the accuracy requirements of 20 cm positioning accuracy for highly precise synthetic aperture radar image processing and to collect GPS radio occultation measurements for atmospheric sounding. In this paper we obtained about 3-5 cm positioning accuracies using the real GPS data of the Gravity Recover and Climate Experiment (GRACE) satellites loaded the Blackjack receiver, a predecessor of IGOR. And it is important to reduce the latency of orbit determination processing in the NRT POD. This latency is determined as the volume of GPS measurements. Thus changing the sampling intervals, we show their latency to able to reduce without the precision degradation as the assessment of their precision.

• Publications of The Korean Astronomical Society
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• v.14 no.1
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• pp.33-37
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• 1999

We have constructed a synthetic spectrum of the 2.5 micron $C_2H$ bands and compared them with diminutive structures in the near-infrared spectra of Comets P/Halley and West (1976 VI). We found that the Q branches of the $C_2H$ bands coincide with two small emission peaks in the spectra of the comets. We undertook Monte Carlo simulations using observed emission intensities of $C_2$ and possibly $C_2H$ in Comet P/Halley in order to derive a lifetime range of $C_2H$ and a production rate at the time of observations of P/Halley. We obtained a $C_2H$ production rate of $1\times10^{27}\;sec^{-1}$ for P/Halley on December 20, 1985, assuming the 2.5 micron features are due to $C_2H$. We derived a very short lifetime (<100 seconds) of $C_2H$ at 1AU heliocentric distance, assuming that the only parent molecule for $C_2H$ and $C_2$ is $C_2H$. Using this short lifetime we were unable to fit our $C_2$ distribution model to $C_2$ distribution curves observed by O'Dell et al.(1988), because our curve shows a steep slope compared with the observed one. We conclude that there must be significant additional source(s) for $C_2H$ and $C_2$ other than $C_2H_2$.