• Journal of Soil and Groundwater Environment
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• v.26 no.4
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• pp.27-43
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• 2021

Since climate factors, such as precipitation, temperature, etc., show repeated patterns every year, it can be said that future changes can be predicted by analyzing past climate data. As with groundwater, seasonal variations predominate. Therefore, when a drought occurs, the groundwater level is also lowered. Thus, a change in the groundwater level can represent a drought. Like precipitation, groundwater level changes also have a high correlation with drought, so many researchers use Standard Groundwater Level Index (SGI) to which the Standard Precipitation Index (SPI) method is applied to evaluate the severity of droughts and predict drought trends. However, due to the strong interferences caused by the recent increase in groundwater use, it is difficult to represent the droughts of regions or entire watersheds by only using groundwater level change data using the SPI or SGI methods, which analyze data from one representative observation station. Therefore, if the long-term groundwater level changes of all the provinces of a watershed are analyzed, the overall trend can be shown even if there is use interference. Thus, future groundwater level changes and droughts can be more accurately predicted. Therefore, in this study, it was confirmed that the groundwater level changes in the last 5 years compared with the monthly average groundwater level changes of the monitoring wells installed before 2015 appeared similar to the drought occurrence pattern. As a result of analyzing the correlation with the water storage yields of 3,423 agricultural reservoirs that do not immediately open their sluice gates in the cases of droughts or floods, it was confirmed that the correlation was higher than 56% in the natural state. Therefore, it was concluded that it is possible to re-evaluate agricultural droughts through long-term groundwater level change analyses.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.2B
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• pp.141-153
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• 2009

The occurrence causes of the extreme rainfall to happen in Korea can be distinguished with the typhoons and local downpours. The typhoon events attacked irregularly to induce the heavy rainfall, and the local downpour events mean a seasonal rain front and a local rainfall. Almost every year, the typhoons and local downpours that induced a heavy precipitation be generated extreme disasters like a flooding. Consequently, in this research, There were distinguished the causes of heavy rainfall events with the typhoons and the local downpours at Korea. Also, probability precipitation was computed according to the causes of the local downpour events. An evaluation of local downpours can be used for analysis of heavy rainfall event in short period like a flash flood. The methods of calculation of probability precipitation used the parametric frequency analysis and the Empirical Simulation Technique (EST). The correlation analysis was computed between annual maximum precipitation by local downpour events and sea surface temperature, moisture index for composition of input vectors. At the results of correlation analysis, there were revealed that the relations closely between annual maximum precipitation and sea surface temperature. Also, probability precipitation using EST are bigger than probability precipitation of frequency analysis on west-middle areas in Korea. Therefore, region of west-middle in Korea should prepare the extreme precipitation by local downpour events.

• Clinical and Experimental Pediatrics
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• v.48 no.3
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• pp.266-275
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• 2005

Purpose : Acute respiratory tract infections are the most common illnesses in children. The great majority of these infections involving lower respiratory tracts infections(LRTIs) are caused by respiratory viruses such as respiratory syncytial virus(RSV), parainfluenza virus(PIV), influenza virus (Flu), and adenovirus(ADV), etc. Our purpose was to determine seasonal epidemiology and clinical characteristic features of each viral infection. Methods : Nasopharyngeal aspirate(NPA)s were collected from 4,554 hospitalized children diagnosed as LRTIs on the first day of admission. The study period was from September 1998(Autumn) through May 2003(Spring). Respiratory viruses were detected in 881(19 percent) cases by isolation of the virus or by antigen detection method using indirect immunofluorescent staining. We reviewed the medical records of 837 cases retrospectively. Results : The identified pathogens were RSV in 485 cases(55 percent), PIV in 152 cases(17 percent), FluA in 114 cases(13 percent), ADV in 79 cases(9 percent) and FluB in 51 cases(6 percent). Outbreaks of RSV occurred every year, mostly in the November through December period and of PIV in the April through June period. LRTIs by FluA reached the highest level in January, 2002. FluB infection showed an outbreak in April, 2002. The clinical diagnoses of viral LRTIs were bronchiolitis in 395 cases(47 percent), pneumonia in 305 cases(36 percent), croup in 73 cases(9 percent) and tracheobronchitis in 64 cases(8 percent). Conclusion : Viruses are one of the major etiologic agents of acute LRTIs in chidren. Therefore, we must continue to study their seasonal occurrence and clinical features to focus on management, and also for reasons of prevention.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.2
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• pp.175-187
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• 1997

Benthic community structure was studied in Chinhae Bay during 3 years from June 1987 to May 1990, based on the samples from 12 stations on the seasonal, bimonthly or monthly basis (lim and Hong, 1994a, b). A total of 287 species was sampled with mean density of $1045.5\;ind./m^2$ and biomass of $98.48g/m^2$ during studyperiods. Of these species, there were 91 species of crustaceans $(31.7\%)$, 88 of polychaetes $(30.7\%)$, 56 of molluscs $(19.5\%)$, 22 of echinoderms and 30 of the micellaneous species. Polychaetes were density-dominant faunal group with a density of $824.7\;ind./m^2$, comprising of $18.6\%$ of the total density of the benthic animals. It was followed by molluscs with $14.62\;ind./m^2$ $($14.4\%\;of\;the\;total\;density)$ crustaceans with $50.5\;ind/m^2\;(4.6\%)$ and echinoderms with $13.4\;ind/m^2\;(4.6\%)$. Molluscs were the biomass-dominant faunal group with a mean biomass of $54.62\;g/m^2$. It was followed by polychaetes with $21.74\;g/m^2$ and echinoderms with $6.66\;g/m^2$. Based on community analysis, species richness, diversity and evenness showed decreasing trends toward the inner bay from outer stations, whereas dominance showed increasing. The three most dominant species Lumbrineris longifolia, Paraprionospio pinnata and Theora fragilis had densities over $40\%$ of the total density of benthic organisms in Chinhae Bay. Seasonal changes of benthic communities in the inner bay were high compared to those of the outer bay. It was mainly due to the occurrence of hypoxic condition in the inner area of the bay. Cluster analysis showed that the benthic community could be divided into four stational groups, that is, Group 1, the innermost area, which received the most heavy anthropogenic effects including seawage and waste water, Group II, the central area of the bay, Group III, the transitional area, Group IV, the mouth pan of the bay exposed to the open sea. The areal groups based on the environmental factors coincided with the zonal groups from the species composition. This fact suggests that the overall spatial distribution of macrobenthos in Chinhae Bay was controlled by the sediment organic carbon content of the bay.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.7 no.2
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• pp.51-59
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• 2002

The seasonal variation in species composition and abundance distribution of zooplankton was studied in the Seomjin river estuary along the salinity gradients. In this estuary, marine taxa predominated in all seasons and very limited number of freshwater species appeared. The total abundances showed a seasonal fluctuation. The highest total abundance appeared in spring with over 3,000 individuals/m$^3$. In summer, the high abundance was sustained although it decreased a little. The abundance was minimal in fall with about 500 individuals/m$^3$. When the study area was divided into three salinity regimes, oligohaline (salinity less than 5 psu), mesohaline (5${\sim}$18 psu), and polyhaline zone (over 18 psu), the zone of high abundance as well as the composition of zooplankton community in each salinity regime changed seasonally. In fall, marine copepods predominated in oligohaline zone while marine species other than crustaceans dominated in polyhaline zone. However, in winter copepods predominated in all area. In spring and summer, holozoic dinoflagellate Noctiluca scintillans dominated in higher salinity regimes. We listed major copepod species of each salinity regime for each season with the ranges of water temperatures (T) and salinities (S) of their occurrence. T, S's of maximum abundances of those major copepod species were also reported. The observed very wide tolerance ranges of major copepod species for salinity suggested that the concept of 'indicator species' should be used in quantitative context rather than qualitative.

• Journal of the Korean Society for Marine Environment & Energy
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• v.15 no.3
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• pp.257-262
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• 2012

This study was conducted to verify the performance of the solar water circulation apparatus that was installed in a semi-closed sea area of Tongyeong to improve the water quality through removing thermocline and oxygen depleted water mass, and to prevent the occurrence of red tides caused by eutrophication. From 8 weeks of experiments, we found that the thermocline in the semi-closed sea area has been removed gradually after installation of the apparatus. The initial temperature of surface and bottom was $27.9^{\circ}C$ and $23.8^{\circ}C$, respectively and it was changed to $22.1^{\circ}C$ in both depth. In case of DO concentration, there was a big gap between surface (5.49 mg/L) and bottom (2.61 mg/L) and was an oxygen depleted water mass in the bottom area at initial. However DO concentration in bottom layer has increased gradually after operation (6.19 mg/L) and the oxygen depleted water mass has removed. Due to the effects of seasonal variation and the operation of the solar water circulation apparatus for 8 weeks, COD concentration decreased from 5.61 mg/L to 2.36 mg/L in surface area, and from 6.08 mg/L to 1.73 mg/L in bottom area. Dissolved inorganic nitrogen concentration also decreased from 0.135 mg/L to 0.050 mg/L in surface area, and from 0.076 mg/L to 0.051 mg/L in bottom area. This research was conducted from July to September, and it might be possible that the variation of water quality was affected by both seasonal variation and the operation of the water circulation apparatus. Hence a further research is required to verify the performance of the water circulation apparatus itself and to monitor dissolved inorganic nitrogen and phosphorous concentrations as well as Chl-a.

• Korean Security Journal
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• no.61
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• pp.109-135
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• 2019

The purpose of this study is to investigate the occupational diseases(the number of medical treatment) of fire officials by using time-series analysis. The results of the study are as follows. First, the average rates of the occupational diseases of fire officials were as follows: ① internal diseases were the highest at 9.24% in December, the lowest at 7.76% in February, ② otolaryngologic diseases were the highest at 9.29% in December, the lowest at 6.74% in August, ③ dermatological diseases were the highest at 10.03% in July, the lowest at 7.35% in January and February, ④ surgical diseases were the highest at 10.38% in November, the lowest at 5.62% in February, ⑤ orthopedic diseases were the highest at 9.69% in March, the lowest at 7.52% in November, ⑥ neurosurgical diseases were the highest at 9.33% in April, the lowest at 6.82% in February, ⑦ neurological diseases were the highest at 9.47% in December, the lowest at 7.06% in October, and ⑧ mental health diseases were the highest at 9.93% in December, the lowest at 6.51% in May. Second, the seasonal decomposition of the disease occurrence of fire officials were described by assigning seasonal factor(S), trend factor(T), circulation factor(C) and irregular factor(R): ① internal diseases were 1.075(S) × 189.355(T·C) × 1.174(R) = 238.975(F), ② otolaryngologic diseases were 1.023(S) × 69.605(T·C) × 1.040(R) = 74.000(F), ③ dermatological diseases were 1.002(S) × 73.088(T·C) × 0.874(R) = 64.000(F), ④ surgical diseases were 1.099(S) × 27.229(T·C) × 0.669(R) = 20.000(F), ⑤ orthopedic diseases were 1.115(S) × 73.182(T·C) × 1.213(R) = 99.000(F), ⑥ neurosurgical diseases were 0.993(S) × 27.836(T·C) × 1.303(R) = 36.000(F), ⑦ neurological diseases were 1.029(S) × 62.417(T·C) × 1.152(R) = 74.000(F), and ⑧ mental health diseases were 1.210(S) × 8.781(T·C) × 1.035(R) = 11.000(F).

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.18 no.4
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• pp.214-226
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• 2013

To understand the changing patterns in phytoplankton communities, we conducted 12 surveys along the Nakdong River, its estuary, and adjacent coastal areas between January 2011 and October 2012 (during the period of barrage construction and sediment dredging). Monthly precipitation ranged from 0 to 502 mm during the survey period, and salinity ranged between 0.1 psu and 0.3 psu in the Nakdong River, regardless of the depth, indicating no seawater influence, while salinity showed large seasonal fluctuations in the estuarine and coastal station, ranging from 0.1 psu to 34.8 psu. A total of 402 phytoplankton species were identified, 178 species from the river and 331 species from the estuary and coastal areas. Phytoplankton standing crop increased in 2012 compared to that in 2011, and was found to be highest in the river, followed by the estuary and coastal areas. Among the top 20 species in frequency of occurrence and dominance, Stephanodiscus spp., Aulacoseira granulata, and Aulacoseira granulata var. angustissima and Pseudo-nitzschia spp. were important species along the river-estuary-coastal areas. Diatoms were the major taxonomic group inhabiting the Nakdong river-estuary-coastal areas. A comparison of seasonal dominant phytoplankton species revealed a slight decrease over the years, from 13 species in 2011 to 10 species in 2012. However, no significant difference was found in the diversity of phytoplankton species between the two survey years, although lightly greater diversity was observed in the coastal areas than in the river and estuary. Cluster analysis with community composition data revealed that the community structure varied significantly in 2011 depending on the time of survey, while in 2012, it hardly showed any variation and was simpler. An increase in the phytoplankton standing crop, fewer dominant species, and simpler community structure in 2012 compared to those in 2011 are probably due to the rapid environmental changes along the Nakdong River. To investigate these ecological relationships, it is necessary to conduct further studies focusing on integrated analyses of biocenosis, including phytoplankton with respect to the changes in nutrient distribution, variation of freshwater discharge, and effect area of freshwater in the Nakdong estuary and adjacent coastal areas.

• Horticultural Science & Technology
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• v.31 no.5
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• pp.523-530
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• 2013

This study investigated the influence of seasonal incidence and defoliation degree caused by Marssonina blotch (Diplocarpon mali Harada et Sawamura) on shoot growth and fruit quality of 'Fuji'/M.9 apple tree. The occurrence of marssonina blotch in Gunwi region was observed from the mid of July 2009, and percentage of defoliation was about 10% in the end of October. In 2010, that started in the early of June. By the end of September, percentage of defoliation was 20% and it reached 50% in late October. Secondary growth of terminal shoot in 2010 was three times as much as that in 2009. In 2009, the soluble solid contents and the red color (hunter a value) during fruit maturation increased to $13.8^{\circ}Brix$ and 16.2, respectively. In 2010, the soluble solid content during fruit maturation remained in the $12.1-12.6^{\circ}Brix$ range after early October, and the red color began to increase after the end of September when the percentage of defoliation was 20%. As for fruit quality by defoliation degree, the red color decreased when defoliation percentage of bourse shoot at the end of October was more than 30%. Fruit weight and soluble solids also decreased when defoliation percentage was more than 50%. Fruit length and diameter of over 30% defoliation treatments begun to decrease after the middle of August, compared with those of under 30% defoliation treatment. Photosynthetic rate of the leaves that was located at the secondary growth of bourse shoot was similar to that of leaves which was located at the middle of bourse shoot. However, the size and the soluble solid content of fruit were not affected by photosynthesis activities of bourse shoot leaves which was develop in the secondary shoot growth.

• Journal of The Geomorphological Association of Korea
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• v.20 no.3
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• pp.95-107
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• 2013

In order to examine the temperature regime responsible for periglacial processes, air and ground temperatures were monitored from October 2010 to May 2011 at a subalpine bare patch (1,710m asl) of Mt. Halla. Four thermistor sensor probes were installed at 55 cm above a ground surface and depths of 2 cm, 10 cm, and 20 cm, respectively. A mean air temperature is $-0.1^{\circ}C$, while mean ground temperatures are $1.8^{\circ}C$ at 2 cm, $2.6^{\circ}C$ at 10 cm and $3.2^{\circ}C$ at 20 cm deep. A mean monthly ground temperature at 2 cm deep demonstrates below $0^{\circ}C$ successively from January to March, while those at 10 cm and 20 cm deep show no sub-zero temperature. A total of 72 freeze-thaw cycle was observed in air temperature. However, the numbers in ground temperature reduced into 17 at 2 cm, 8 at 10 cm, and 3 at 20 cm deep. The cycles of air temperature and ground temperature at 2 cm deep mostly fluctuated diurnally, while those of ground temperature at 10 cm and 20 cm deep exhibited a several-daily oscillation. Snow cover over 55 cm high remained from January to early April, and it seemed to disappear completely on April 16. A seasonal frost of at least 2 cm thick was formed on late December and the isotherm of $0^{\circ}C$ descended slowly into 10 cm deep on late March to early April due to the insulating snow cover. It showed the maximum freezing depth of 20 cm on April 7 to 14 and then thawed rapidly so that the frozen ground did not longer after April 17. Periglacial processes are predominant during a freezing period than a thawing period when the ground surface is still covered with snow. The periglacial mass movement in the subalpine zone of Mt. Halla is mainly generated by frost creep in terms of the occurrence depth of diurnal freeze-thaw cycle and the maximum freezing depth of ground.