• Journal of Environmental Science International
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• v.17 no.3
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• pp.269-273
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• 2008

The objective of this study was to evaluate the relationship between nutrients and phytoplankton. This study was done by the comparison to two costal areas Mokpo, which inflow fresh water, and Wando. In August, salinity of the sea water decreased by 3.5-4.5%o in Mokpo coastal area, but was not nearly decreased in Wando coastal area. This suggests a lot of fresh water inflow in Mokpo coastal area. DIN and DIP were decreased by water temperature increasing in Wando. However, in Mokpo, DIN and DIP were increased greatly during the summer season. Nitrogen was limited to a 10 NIP ratio especially during the summer season in Wando coastal area while phosphorus in Mokpo coastal area was limited with over 28 N/P ratio in all the seasons. Coefficient of determination$(r^2)$ between DIP and Chl.-a was 0.91 in Mokpo coastal area. On the other hand, Coefficient of determination$(r^2)$ between Chl.-a and DIN, DIP were 0.93 and 0.89, respectively, in Wando coastal area. These results suggest DIP in Mokpo and DIN and DIP in Wando might be limited at the increase of phytoplankton.

• Journal of Environmental Health Sciences
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• v.38 no.6
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• pp.460-471
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• 2012

Objectives: Due to global warming resulting from climate change, there has been increasing interest in the relationship between temperature and mortality. These temperature-related deaths depend on diverse conditions related to a given place and person, as well as on time. This study examined changes in the impact of high temperatures on death in summer, using the effect and burden of elevated temperatures on deaths in Seoul and Daegu. Methods: A Poisson regression model was used to estimate short-term temperature effects on mortality. Temperature-related risks were divided into three time periods of equal length (1996-2000, 2001-2005, and 2006-2010). In addition, in order to compare the impact of high temperatures on deaths, this study calculated the proportion of attributable deaths to population, which simultaneously considers the threshold and the slope above the threshold. Results: The effect and burden of high temperatures on deaths is high in Daegu. However, the impact (i.e. the effect and burden) of elevated summer temperatures on deaths has declined over the past 15 years. Sensitivity analyses using alternative thresholds show the robustness of these findings. Conclusion: This study suggests that the attributable burden of high temperatures on deaths to be more plausible than relative risk or threshold for comparing the health impact of high temperatures across populations. Moreover, these results contain important implications for the development or the adjustment of present and future strategies and policies for controlling the temperature-related health burden on populations.

• Journal of Aquaculture
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• v.9 no.1
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• pp.65-71
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• 1996

To estimate the variation of food organisms on the corrugated PVC sheets, we analysed the chlorophyll a and. pheopigments of the benthic microalgae on the sheets from the oyster culture ponds. We estimated the standing crops as the amounts of chlorophyll a, and the physiological state of cells as the pheopigments level in the benthic microalgae. The amount of chlorophyll a was increased by immersion time in winter but the peak was observed every two weeks in summer, while the ratio of pheopigments was highest in summer but the low level was observed in spring and autumn. These seasonal variation were well coincided with the natural spawning season and the good microalgae nutritional valance.

• Ocean and Polar Research
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• v.29 no.2
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• pp.113-121
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• 2007

The sound wave in the sea propagates under the effect of water depth, sound speed structure, sea surface roughness, bottom roughness, and acoustic properties of bottom sediment. In shallow water, the bottom sediments are distributed very variously with place and the sound speed structure varying with time and space. In order to investigate the seasonal propagation characteristics of low-frequency sound wave in the Yellow Sea, propagation experiments were conducted along a track in the middle part of the Yellow Sea in spring, summer, and autumn. In this paper we consider seasonal variations of the sound speed profile and propagation loss based on the measurement results. Also we quantitatively investigate variation of bottom loss by dividing the propagation loss into three components: spreading loss, absorption loss, and bottom loss. As a result, the propagation losses measured in summer were larger than the losses in spring and autumn, and the propagation losses measured in autumn were smaller than the losses in spring. The spreading loss and the absorption loss did not show seasonal variations, but the bottom loss showed seasonal variations. So it was thought that the seasonal variation of the propagation loss was due to the seasonal change of the bottom loss and the seasonal variation of the bottom loss was due to the change of the sound speed profile by season.

• Journal of the Korea Institute of Military Science and Technology
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• v.21 no.3
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• pp.306-314
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• 2018

In maritime environment, it is necessary to understand the characteristics of sunglint since it may degrade the target detection performance of the infrared sensor mounted weapons. In this paper, sunglint in LWIR band is modeled using the slope distribution of the sea surface, and is verified by comparing the radiance of a simulated result with that of the real world. According to the simulation, sunglint is critical when the solar zenith angle is over $60^{\circ}$. The peak radiance of sunglint grows as the solar zenith angle increases until it reaches $83^{\circ}$ and has a large difference depending on the solar zenith angle when the wind speed is small. Finally, seasonal and temporal characteristics of sunglint effects are analyzed. In summer, sunglint is dominant in the horizon near the solar azimuth right after sunrise and before sunset. However, in winter, the influence of sunglint lasts even during the daytime since the elevation of the sun is much lower than in summer.

• KIEAE Journal
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• v.13 no.2
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• pp.3-12
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• 2013

Recently, New Han-ok is in prevail because it has many good qualities as a dwelling. But the New Han-ok dwellers' needs and satisfaction ratio on their houses are not investigated yet. So, surveys on satisfaction ratio for New Han-ok were carried out to know New Han-ok's existing conditions and inhabitant's responses on New Han-ok dwellings. Followings are results. 1) Dwellers response that it is cool in summer and it is cold in winter. So, design and construction method against cold is needed for New Han-ok. 2) Window is the most picking element of New Han-ok for house improvement. 3) Window opening is main control method for cooling in summer. Warming sources in winter are various such as electricity, gas, oil, wood, etc. 4) PVC window structure and glasses were used for New Han-ok's window system as well as wooden window structure and Han-gi. 5) Interviewees are generally satisfied with New Han-ok's exterior view and inner spaces. Almost no humidifier is used. These results could be used for improvement of Han-ok and basic material for New Han-ok design.

• Journal of Environmental Science International
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• v.27 no.3
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• pp.155-165
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• 2018

Observations were conducted in Uiseong Binggye-ri Ice Valley of Korea, where a low temperature talus is located. The talus temperature at Ice Hole near the lower end of the talus remained at $0^{\circ}C$ until summer or autumn and averaged $-0.3^{\circ}C$ over 2 years. The talus temperature at Warm Hole was much higher than the external air temperature during autumn and winter. The outflow of warm air at Warm Hole begins in the late summer of fall. The direction of airflow through the talus surface was determined by the relationship between talus temperature and external air temperature. Annual variations in talus temperature and air exchange between the talus and the external environment can be divided into four periods. It was found that the airflow directions at Warm Hole and Ice Hole were not necessarily opposites. The outflows from the talus at Ice Hole and Warm Hole can occur simultaneously.

• Korean Journal of Ecology and Environment
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• v.38 no.spc
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• pp.39-43
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• 2005

The dynamics of water quality with the storm events were analyzed in a small reservoir for irrigation, Lake Wangkung. Water quality of the inflowing stream fluctuated seasonally with the variation of flow rate. Thermal stratification was consistent from April to October below 2 m depths and anoxic layer was developed below 2 m depth in summer. The unique feature of temperature showed that thermal stratification was disrupted by a heavy rain event during monsoon, but hypolimnetic hypoxia were reestablished after a few days. Phosphorus and nitrogen increased immediately following storm events. The marked increase may be due to the input of P-rich storm runoff from the watershed. Internal phosphorus loading can be one of the explanations for TP increases in summer. When there was a storm, total populations of phytoplankton and zooplankton was reduced immediately following the storm, indicating possible flushing of algae and zooplankton. After a lag period of low-density the plankton population bloomed to a peak again within five days after the storm. Turbid water in lake became clear again which coincided with the time of the phytoplankton buildup. The results demonstrate that water quality is regulated greatly by rainfall intensity in Lake Wangkung.

• Korean Journal of Ecology and Environment
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• v.38 no.spc
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• pp.12-16
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• 2005

Seasonal change in cell number and biomass expressed as chlorophyll a of picophytoplankton community in surface waters was investigated in the north basin of Lake Biwa from September 2001 to November 2002. Two main peaks, in May and summer (from July to October), were observed by change of the cell density of picophytoplankton. It is considered that peak in May was due to water temperature rise and summer peak was attributed to mass-specific nutrient uptake by picophytoplankton. Horizontal distribution in cell number and biomass of picophytoplankton community in surface water of Lake Biwa was investigated at 56 stations on June 6 ${\sim}$ 7 2002. DIN and DIP concentrations were lower in the north basin than in the south basin. The cell density and chlorophyll a of picophytoplankton were distributed almost uniformly in all area. The contribution of picophytoplankton to total phytoplankton chlorophyll a was higher in the north basin than in the south basin. These results suggest that picophytoplankton is important as a primary producer in low nutrient periods and areas of Lake Biwa.

• Korean Journal of Ecology and Environment
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• v.44 no.4
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• pp.337-346
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• 2011

We investigated nutrient loading and trophic states in a coastal estuarine system in the Asan estuary by assessing phytoplankton biomass and using the trophic index (TRIX). The monthly and yearly nutrient loading (TN, TP) from freshwater discharge from the Asan and Sapgyo reservoirs into the estuary were estimated and analyzed with related factors. Monitoring data (physio-chemical and biological variables) collected at five estuary stations were used to assess trophic states. Descriptive statistics of total phytoplankton cells, chl a concentrations and primary productivity were also used to assess seasonal trophic status. N loading from freshwater ranged $1.0{\sim}1.3{\times}10^4$ ton yearly. The yearly P loading ranged between 350 and 400 ton during 2004~2006, increasing to 570 ton in 2007. Regression results suggest that DIN and DSi were correlated with freshwater discharge at the upper region. Based on phytoplankton biomass and total cell abundance, the trophic state of the estuary was found to be eutrophic during spring due to phytoplankton bloom. Primary productivity level was remarkably high, especially in summer coinciding with high nutrient loading. Pheopigments increased during warm seasons, i.e. summer and fall. Trophic index results indicate that the trophic state varied between mesotrophic and eutrophic in the estuary water body, especially in the upper region. The results suggest that phytoplankton production was regulated by nutrient loading from freshwater whereas biomass was affected by other properties than nutrient loading in the Asan Estuary ecosystem.