• Korean Journal of Remote Sensing
• /
• v.36 no.3
• /
• pp.461-474
• /
• 2020

Korea launched Geostationary Environmental Monitoring Satellite (GEMS), a UV/visible spectrometer that measure pollution gases on 18 February 2020. Because satellite retrieval is an ill-posed inverse solving process, the validation with ground-based measurements or other satellite measurements is essential to obtain reliable products. For this purpose, satellite-based OMI and OMPS total column ozone (TCO), and ground-based Pandora TCO in Busan and Seoul were selected for future GEMS validation. First of all, the goal of this study is to validate the ground ozone data using characteristics that satellite data provide coherent ozone measurements on a global basis, although satellite data have a larger error than the ground-based measurements. In the cross validation between Pandora and OMI TCO, we have found abnormal deviation in ozone time series from Pandora #29 observed in Seoul. This shows that it is possible to perform inverse validation of ground data using satellite data. Then OMPS TCO was compared with verified Pandora TCO. Both data shows a correlation coefficient of 0.97, an RMSE of less than 2 DU and the OMPS-Pandora relative mean difference of >4%. The result also shows the OMPS-Pandora relative mean difference with SZA, TCO, cross-track position and season have insignificant dependence on those variables.In addition, we showed that appropriate thresholds depending on the spatial resolution of each satellite sensor are required to eliminate the impact of the cloud on Pandora TCO.

• Korean Journal of Remote Sensing
• /
• v.36 no.5_1
• /
• pp.807-821
• /
• 2020

The objective of this study is to evaluate the applicability of representative spatio-temporal fusion models developed for the fusion of mid- and low-resolution satellite images in order to construct a set of time-series high-resolution images for crop monitoring. Particularly, the effects of the characteristics of input image pairs on the prediction performance are investigated by considering the principle of spatio-temporal fusion. An experiment on the fusion of multi-temporal Sentinel-2 and RapidEye images in agricultural fields was conducted to evaluate the prediction performance. Three representative fusion models, including Spatial and Temporal Adaptive Reflectance Fusion Model (STARFM), SParse-representation-based SpatioTemporal reflectance Fusion Model (SPSTFM), and Flexible Spatiotemporal DAta Fusion (FSDAF), were applied to this comparative experiment. The three spatio-temporal fusion models exhibited different prediction performance in terms of prediction errors and spatial similarity. However, regardless of the model types, the correlation between coarse resolution images acquired on the pair dates and the prediction date was more significant than the difference between the pair dates and the prediction date to improve the prediction performance. In addition, using vegetation index as input for spatio-temporal fusion showed better prediction performance by alleviating error propagation problems, compared with using fused reflectance values in the calculation of vegetation index. These experimental results can be used as basic information for both the selection of optimal image pairs and input types, and the development of an advanced model in spatio-temporal fusion for crop monitoring.

• Journal of Technology Innovation
• /
• v.27 no.4
• /
• pp.21-48
• /
• 2019

In the basic research field, quantitative expansion is carried out with active support from the government, but there is no research and policy data suggesting systematic investment plans or data-based financial requirements yet. Therefore, this study predicted future financial requirements of basic research support programs by using time series prediction model. In order to consider various factors including the characteristics of the basic research field, we selected the ARIMAX model which can reflect the effect of multi valuable factors rather than the ARIMA model which predicts the value of single factor over time. We compared the predictions of ARIMAX and ARIMA models for model suitability and found that the ARIMAX model improves the prediction error rate. Based on the ARIMAX model, we predicted the fiscal spending of basic research support programs for five years from 2017 to 2021. This study has significance in that it considers the financial requirements of the basic research support programs as a pilot research conducted by applying a time series model, which is a statistical approach, and multi-variate rather than single-variate. In addition, considering the policy trends that emphasize the importance of basic research investment such as 'the expansion of basic research budget twice', which is the current government's national policy task, it can be used as reference data in establishing basic research investment strategy.

• Environmental Analysis Health and Toxicology
• /
• v.29
• /
• pp.12.1-12.8
• /
• 2014

Objectives Cohort studies of associations between air pollution and health have used exposure prediction approaches to estimate individual-level concentrations. A common prediction method used in Korean cohort studies is ordinary kriging. In this study, performance of ordinary kriging models for long-term particulate matter less than or equal to $10{\mu}m$ in diameter ($PM_{10}$) concentrations in seven major Korean cities was investigated with a focus on spatial prediction ability. Methods We obtained hourly $PM_{10}$ data for 2010 at 226 urban-ambient monitoring sites in South Korea and computed annual average $PM_{10}$ concentrations at each site. Given the annual averages, we developed ordinary kriging prediction models for each of the seven major cities and for the entire country by using an exponential covariance reference model and a maximum likelihood estimation method. For model evaluation, cross-validation was performed and mean square error and R-squared ($R^2$) statistics were computed. Results Mean annual average $PM_{10}$ concentrations in the seven major cities ranged between 45.5 and $66.0{\mu}g/m^3$ (standard deviation=2.40 and $9.51{\mu}g/m^3$, respectively). Cross-validated $R^2$ values in Seoul and Busan were 0.31 and 0.23, respectively, whereas the other five cities had $R^2$ values of zero. The national model produced a higher cross-validated $R^2$ (0.36) than those for the city-specific models. Conclusions In general, the ordinary kriging models performed poorly for the seven major cities and the entire country of South Korea, but the model performance was better in the national model. To improve model performance, future studies should examine different prediction approaches that incorporate $PM_{10}$ source characteristics.

• Journal of Biosystems Engineering
• /
• v.37 no.3
• /
• pp.177-183
• /
• 2012

Purpose: In near infrared spectroscopy, interactance configuration of a light source and a spectrometer probe can provide more information regarding fruit internal attributes, compared to reflectance and transmittance configuration. However, there is no through study on the parameters of interactance measurement setup. The objective of this study was to investigate the effect of the parameters on the estimation of soluble solids content (SSC) and firmness of muskmelons. Methods: Melon samples were taken from greenhouses at three different harvesting seasons. The prediction models were developed at three distances of 2, 5, and 8 cm between the light source and the spectrometer probe, three measurement points of 2, 3, and 6 evenly distributed on each sample, and different number of fruit samples for calibration models. The performance of the models was compared. Results: In the test at the three distances, the best results were found at a 5 cm distance. The coefficient of determination ($R_{cv}{^2}$) values of the cross-validation were 0.717 (standard error of prediction, SEP=$1.16^{\circ}Brix$) and 0.504 (SEP=4.31 N) for the estimation of SSC and firmness, respectively. The minimum measurement point required to fully represent the spectral characteristics of each fruit sample was 3. The highest $R_{cv}{^2}$ values were 0.736 (SEP=$0.87^{\circ}Brix$) and 0.644 (SEP=4.16 N) for the estimation of SSC and firmness, respectively. The performance of the models began to be saturated when 60 fruit samples were used for developing calibration models. The highest $R_{cv}{^2}$ of 0.713 (SEP=$0.88^{\circ}Brix$) and 0.750 (SEP=3.30 N) for the estimation of SSC and firmness, respectively, were achieved. Conclusions: The performance of the prediction models was quite different according to the condition of interactance measurement setup. In designing a fruit grading machine with interactance configuration, the parameters for interactance measurement setup should be chosen carefully.

• Analytical Science and Technology
• /
• v.18 no.1
• /
• pp.43-50
• /
• 2005

A number of carbonyl compounds including formaldehyde and acetaldehyde are well known for their toxicity and irritancy. Hence, acquisition of both qualitative and quantitative tool for their analysis is essential to resolve issues associated with malodor or indoor pollution. Using HPLC/UV method, we examined various aspects involved in the measurements of formaldehyde in environmental samples. The results of our analysis indicated that its detection was made as low as 0.5 ppb (assuming 5 L of sample volume), while its precision was maintained near 2% in terms of relative standard error (RSE). When the stability of calibration was checked by variability of slope values obtained over long-term period (e.g., one month), its values were found to remain constantly with RSE values of 3%. It was also found that liquid-phase reaction between formaldehyde and DNPH proceed very slowly to attain equilibrium (one and half hour), while requiring adequate amount of DNPH to form their derivatives. The overall results of our study thus suggest that there are a number of factors to consider for the accurate analysis of formaldehyde in ambient air.

• Journal of Environmental Impact Assessment
• /
• v.26 no.1
• /
• pp.11-26
• /
• 2017

Approximate empirical equations obtained by measuring overall noise levels at different distances have been used to evaluate environmental influence of the railway noise though the accurate prediction of noise levels is important. In this paper, a noise prediction model considering the frequency characteristics of noise sources and propagation was suggested to improve the accuracy of noise prediction. The railway noise source was assorted into track, wheel, traction and aerodynamic components and they were characterized with the source strength and speed coefficient at each octave-band frequency. Correction terms for the acoustic roughness and the track/bridge condition were introduced. The sound attenuation from a source to a receiver was calculated taking account of the geometrical divergence, atmospheric absorption, ground effect, diffraction at obstacles and directivity of source by applying ISO 9613-2. For obtaining the source strength and speed coefficients, the results of rolling noise model, numerical analysis and measurements of pass-by noise were analyzed. We compared the predicted and measured noise levels in various vehicles and tracks, and verified the accuracy of the present model. It is found that the present model gives less error than the conventional one, so that it can be applied to make the accurate prediction of railway noise effect and establish its countermeasures efficiently.

• Atmosphere
• /
• v.18 no.3
• /
• pp.183-197
• /
• 2008

The purpose of this study is to summarize tropical cyclone activity in 2007. 24 tropical cyclones of tropical storm (TS) intensity or higher formed in the western North Pacific and the South China Sea in 2007. The total number is less than the thirty-year (1971~2000) average frequency of 26.7. Out of twenty four tropical cyclones, 14 TCs reached typhoon (TY) intensity, while the rest 10 only reached severe tropical storm (STS) and tropical storm (TS) intensity - four STS and six TS storms. The tropical cyclone season in 2007 began in April with the formation of KONG-REY (0701). From April to May, two TCs formed in the western North Pacific in response to enhanced convective activity there. From June to July, convective activity turned inactive over the sea around the Philippines and in the South China Sea, and the subtropical high was weak over the south of Japan. MAN-YI (0704) and USAGI (0705) moved northwestward and hit Japan, bringing serious damage to the country. After August, convective activity became enhanced over the sea east of the Philippines, and the subtropical high turned strong over the sea south of Japan. Many TCs, which formed over the sea east of the Philippines and in the South China Sea, moved westward and hit China and Vietnam. PABUK (0706), WUTIP (0707), SEPAT (0708), WIPHA (0712), LEKIMA (0714) and KROSA (0715) brought serious damage to some countries including China, the Philippines and Vietnam. On the other hand, FITOW (0709) and NARI (0711) moved northward, bringing serious damage to Japan and Korea. After HAIYAN (0716), all four TCs except FAXAI (0720) formed over the sea east of $140^{\circ}E$. Three typhoons among them affected Republic of Korea, MAN-YI (0704), USAGI (0705) and NARI (0711). Particularly, NARI (0711) moved northward and made landfall at Goheng Peninsula ($34.5^{\circ}N$, $127.4^{\circ}E$) in 1815 KST 16 September. Due to $11^{th}$ typhoon NARI, strong wind and record-breaking rainfall amount was observed in Jeju Island. It was reported that the daily precipitation was 420.0 mm at Jeju city, Jeju Island on 16 September the highest daily rainfall since Jeju began keeping records in 1927. This typhoon hit the southern part of the Korean peninsula and Jeju Island. 18 people lost their lives, 14,170 people were evacuated and US$ 1.6 billion property damage was occurred.

• Clinical and Experimental Pediatrics
• /
• v.50 no.9
• /
• pp.896-900
• /
• 2007

Purpose : The aim of this study was to investigate the speech problems in benign rolandic epilepsy (BRE) according to the seizure focus in EEG and semiology. Methods : Twenty three patients [right origin (13 patients) or left side (10 patients)] who met the BRE criteria by International League Against Epilepsy (ILAE) were prospectively enrolled. We excluded the patients who had abnormal MRI or showed both side spikes in EEG. Computerized Speech Lab was used to assess the speech characteristics of the patients. Results : The error pattern of laryngeal articulation in BRE was exclusively substitution of stop consonants, these errors showed more frequent in the left group (16.0% vs 25.5%). Voice onset time (VOT) of stop consonants and Total duration (TD) of word in both groups were prolonged than normal control group, especially in left group (P<0.05). The first formant of vowel /o/ and second formant of /e/ were significantly decreased in left group (P<0.05). The right group scored wider on pitch range ($192.9{\pm}54.0Hz$) and energy range in spontaneous speech ($14.2{\pm}6.4db$) than the left group ($233.3{\pm}12.5Hz$, $19.4{\pm}9.3db$, respectively, P>0.05). Duration of counting (5 to 9) in left group slower than right group ($8.6{\pm}1.7$ vs $7.9{\pm}1.8sec$). Conclusion : Our data suggested that interictal spikes and seizures in either centrotemporal sides, especially left side group, may induce speech problems. We recommend the logopedic and phoniatric evaluations of speech in BRE patients.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.18 no.4
• /
• pp.308-315
• /
• 2012

Hebei Spirit Oil Spill that happened in 2007 had prompted the need of revisiting the coastal safety. In response to this, Korea had made an effort to implement VTS in every coastline in the country. There are a lot of theoretical studies on VTS function nowadays, but coastal VTS are less frequently studied. In this paper, performance analysis results and accident prevention activities of Jindo Coastal VTS center were summarized and the Coastal VTS function are investigated. Jindo Coastal VTS covers relatively wide area and various places with various maritime traffic characteristics are the major navigation vessels, which means that it is important to control these vessels. Since the probability of accidents due to human error is relatively high in coastal area due to negligence tendency of crews during coastal area navigation, coastal VTS has to provide sufficient assistance to navigating vessels. Like most harbour VTS, Coastal VTS provides not only main information service, navigational assistance and traffic organization services but also various services related with advanced search-and-rescue assistance, marine national security, maritime crime prevention, oil spill response, traffic services for non-service vessel, and safety supervision for water leisure boats.