Geostatistical assessment of warm-season precipitation observations in Korea based on the composite precipitation and satellite water vapor data

Park, Sojung,Park, Seon Ki,Lee, Jeung Whan,Park, Yunho Copernicus GmbH 2018 Hydrology and earth system sciences Vol.22 No.6

<P><p><strong>Abstract.</strong> Among the meteorological disasters, heavy rainfalls cause the second largest damage in Korea, following typhoons. To manage the potential disasters due to heavy rainfalls, understanding the observational characteristics of precipitation is of utmost importance. In this study, we investigate the spatial and temporal characteristics of warm-season precipitation in Korea, according to the precipitation types, by conducting the geostatistical analyses such as an autocorrelogram, Moran's <span class='inline-formula'><i>I</i></span> and general <span class='inline-formula'><i>G</i></span> on the composite (radar<span class='thinspace'></span><span class='inline-formula'>+</span><span class='thinspace'></span>station) precipitation data. The <span class='inline-formula'><i>e</i></span>-folding distance of precipitation ranges from 15 to 35<span class='thinspace'></span>km, depending on the spatial distribution, rather than intensity, of precipitation, whereas the <span class='inline-formula'><i>e</i></span>-folding time ranges from 1 to 2<span class='thinspace'></span>h. The directional analyses revealed that the warm-season precipitation systems in Korea, especially those with a high precipitation amount, have high spatial autocorrelations in the southwest-northeast and west-east directions, in association with the frontal rainfalls, convection bands, etc. Furthermore, the cluster versus dispersion patterns and the hot versus cold spots are analyzed through Moran's <span class='inline-formula'><i>I</i></span> and general <span class='inline-formula'><i>G</i></span>, respectively. Water vapor, represented by the brightness temperature, from three Himawari-8 water vapor bands also shows similar characteristics with precipitation but with strong spatial correlation over a much longer distance (<span class='inline-formula'>∼</span><span class='thinspace'></span>100<span class='thinspace'></span>km), possibly due to the continuity of water vapor. We found that, under the <span class='inline-formula'><i>e</i></span>-folding-based standard, the current observation network of Korea is sufficient to capture the characteristics of most precipitation systems; however, under a strict standard (e.g., autocorrelation of 0.6), a higher-resolution observation network is essentially required - especially in local areas with frequent heavy rainfalls - depending on the directional features of precipitation systems. Establishing such an observation network based on the characteristics of precipitation enables us to improve monitoring, tracking, and prediction skills of high-impact weather phenomena as well as to enhance the utilization of numerical weather prediction.</p> </P>

Spatiotemporal Distribution of Dissolved Heavy Metals in Gyeonggi Bay, Korea

Sojung Park,최만식,Dongjun Jang,조동진,Kyunggue Park,Hyojin Lee,Junsik Woo,Taeha Kim,Jongkyu Park 한국해양과학기술원 2020 Ocean science journal Vol.55 No.1

In this study, we investigated the spatial and temporal distribution of heavy metals and nutrients in Gyeonggi Bay, Korea, to determine their present status and seasonal variability, and to identify their sources. Two surveys (May and August 2017) covering the entire Gyeonggi Bay (15 sites) and twelve surveys over four seasons (February, May, August, and November of 2016–2018) covering the Incheon Special Management Area (7 sites) were carried out to collect surface seawaters. Three surveys (January, April, and August of 2015) were also performed to collect seawater samples at Shihwa Lake (16 sites). Although the concentration gradients of nutrient type heavy metals (e.g. copper, nickel, zinc, and cadmium) corresponded to patterns of salinity in both dry and wet seasons, there was little seasonal variability over the three years studied. However, there was evidence that heavy metals were released during mixing with freshwaters in the wet season, likely from river outflow or direct coastal inputs such as effluents from Shihwa Lake. For nutrients, whereas the conservative mixing of dissolved inorganic nitrogen and the release of dissolved inorganic phosphate and dissolved silica were observed in the wet season, the concentrations of organic particles (e.g., chlorophyll-a, particulate organic carbon, and particulate organic nitrogen) had an inverse relationship with salinity in the dry season (May). Scavenged metals (e.g., manganese and cobalt) had non-freshwater coastal sources, such as benthic remobilization from suboxic sediments, and exhibited seasonal variation; they progressively increased in concentration from winter to spring and summer, and dropped to their minimum levels in the fall, which was presumably related to variation in microbial activity in sediments. Based on their relationship with salinity, heavy metals were deduced to be derived from coastal sources such as effluents from Shihwa Lake and freshwater from the Han River.

Distribution and Sources of Dissolved and Particulate Heavy Metals (Mn, Co, Ni, Cu, Zn, Cd, Pb) in Masan Bay, Korea

Sojung Park,최만식,Dongjun Jang,조동진,Kyunggue Park 한국해양과학기술원 2020 Ocean science journal Vol.55 No.1

In this study, we investigated the spatial and temporal distribution and sources of dissolved and particulate heavy metals in Masan Bay, an area that for a long time has been contaminated by waste from surrounding large industrial complexes and metropolitan cities. Surface seawater samples from 16 sites around inner Masan Bay and offshore were collected over four survey periods (October 2015 and June, August, and November 2016). The spatial gradients of dissolved and particulate heavy metal concentrations generally overwhelmed the temporal variability, with a sharp decrease in metal concentrations, as well as salinity, with distance from the innermost site near the river mouth toward offshore. This tendency was maintained throughout all four survey periods. With the exception of zone I (sites 1–4), the concentrations of dissolved and particulate heavy metals showed little spatial variability, although possible sources of heavy metals, such as wastewater treatment plants (WWTPs; Dukdong and Jinhae), were located in the area. The main sources of several heavy metals would be the river water itself, as well as the release processes of river particles. Metalenriched biological particles from river water and WWTP effluent were the main contributors to the particulate metal concentrations during June and August; however, during October and November, the particulate metal concentrations were supplied by detrital particles similar to sediment. The contamination index was calculated using metal concentrations in offshore samples as the background concentrations. Mn, Co, and Zn contamination in zone I ranged from grade 3 to 5, indicating moderate to strong pollution conditions.

Representation of Vegetation Effects on Snow-Covered Albedo in the Noah Land Surface Model with Multi-Physics Options

Sojung Park,Seungbum Hong,Seon K. Park 한국기상학회 2014 한국기상학회 학술대회 논문집 Vol.2014 No.10

Optimization of Multiple Physics Schemes and parameters using the micro-Genetic Algorithm in WRF model for Quantitative Precipitation Forecast in the Eastern Coastal Region of Korea

Sojung Park,Ebony Lee,Seung Yeon Lee,Ji Won Yoon,Seon Ki Park 한국기상학회 2019 한국기상학회 학술대회 논문집 Vol.2019 No.10

Precise Analysis On Peroxide-Selective Carbon Catalyst: Selective Electrochemical Oxygen Reduction Reaction

Sojung Park(박소정),Wooyul Kim(김우열) 대한환경공학회 2021 대한환경공학회 학술발표논문집 Vol.2021 No.11

Comparison of EGFR TKIs for Patients with Lung Cancer Harboring Different EGFR Mutation Types

( Sojung Park ),( Jung Hyun Chang ),( Sung Yong Lee ),( Dojin Kim ),( Yun Su Sim ),( Jeong-seon Ryu ),( Juwhan Choi ),( Su Hwan Lee ),( Yon Ju Ryu ),( Jin Hwa Lee ) 대한결핵 및 호흡기학회 2020 대한결핵 및 호흡기학회 추계학술대회 초록집 Vol.128 No.-

Background Epidermal growth factor receptor (EGFR) mutations in non-small-cell lung cancer predict sensitivity to EGFR tyrosine kinase inhibitors (TKIs). EGFR mutation types are associated with efficacy of EGFR TKIs. We investigated the clinical outcomes of erlotinib, gefitinib, and afatinib according to EGFR mutation type in patients with lung adenocarcinoma. Methods Between May 2010 and December 2018, we investigated 363 patients with advanced lung adenocarcinoma harboring EGFR mutations who received EGFR TKIs. Efficacies of EGFR TKIs such as response rate, progression-free survival (PFS), and overall survival (OS) were retrospectively evaluated according to exon 19 deletion (E19del), L858R point mutation (L858R) and uncommon mutations. Results The frequency of E19del was 48.2%, that of L858R was 42.4%, and that of uncommon mutations was 9.4%. E19del and L858R were associated with superior PFS and OS compared with uncommon mutations. Erlotinib showed significantly inferior OS than other TKIs (30.8 ± 3.3 in erlotinib vs. 48.4 ± 6.3 in gefitinib vs. 39.1 ± 4.3 in afatinib; P = 0.031) in patients with L858R. Gefitinib showed significantly inferior PFS (4.6 ± 1.1 in gefitinib vs. 10.6 ± 2.7 in erlotinib vs. 11.6 ± 2.7 in afatinib; P = 0.049) in patients with uncommon mutations. Conclusion Significant differences were found in clinical outcomes among EGFR TKIs depending on EGFR mutation type.

Does hunger for bonuses drive the dependence between claim frequency and severity?

Park, Sojung C.,Kim, Joseph H.T.,Ahn, Jae Youn Elsevier 2018 Insurance, mathematics & economics Vol.83 No.-

<P><B>Abstract</B></P> <P>Auto ratemaking models have traditionally assumed independence between claim frequency and severity. With the development of insurance claim models that can accommodate dependence between claim frequency and severity, a series of recent studies has revealed that the aforementioned dependence between frequency and severity exists for auto insurance claims, demonstrating the validity of such models. However, the underlying process that creates this dependence has received little attention in the literature. Thus, we show that a rational decision-making process of drivers known as bonus hunger can systemically induce dependence between the claim frequency and severity even when the ground-up loss frequency and severity are, in fact, independent. Our model, based on the random effect model coupled with the standard bonus–malus system, successfully explains the seemingly contradictory results from the existing literature of weak positive dependence, between the claim frequency and severity for liability claims, and moderately negative dependence for collision claims. Our findings show that the seemingly contradicting dependence structures reported in the literature may be neither accidental nor sample specific. Furthermore, the bonus-hunger process also implies that the level of the claim frequency-severity dependence varies across bonus–malus classes, suggesting that a uniform dependency structure may not be appropriate for auto ratemaking modeling.</P>

Effects of the Interannual Variability in the Growing Season of Deciduous Needleleaf Forest in Siberia on the Local Climate

Sojung Park,Hyeon-Ju Gim,Seon Ki Park 한국기상학회 2015 한국기상학회 학술대회 논문집 Vol.2015 No.10

Convergence characteristics of a domain decomposition scheme for approximation of quantum forces

Sojung Park,Jungim Yoon,위대현 한국물리학회 2013 Current Applied Physics Vol.13 No.7

We investigate the convergence characteristics of a domain decomposition scheme to approximately compute quantum forces in the context of semiclassical Bohmian mechanics. The study is empirical in nature. Errors in the approximate quantum forces are compiled while relevant parameters in the numerical scheme are systematically changed. The compiled errors are analyzed to extract underlying trends. Our analysis shows that the number of Bohmian particles used in discretization has relatively weak influence on the error, while the length scale of interaction among subdomains controls the error in most cases. More precisely, the overall numerical error decreases as the length scale of interaction among subdomains decreases, if the error due to the truncation of the tail of the probability density distribution is adequately controlled. Our results suggest that it may be necessary to develop an efficient method to effectively control the error due to the truncation of the tail. Further studies, especially rigorous mathematical ones, should follow to understand and improve the behavior of the scheme.