• Journal of the Korean Society of Marine Environment & Safety
• /
• v.29 no.4
• /
• pp.297-306
• /
• 2023

Saemangeum Lake is the largest artificial lake in Korea. The continuous deterioration of lake water quality necessitates the introduction of novel water quality management strategies. Therefore, this study aims to identify the spatiotemporal water quality characteristics of Saemangeum Lake using data from the National Water Quality Measurement Network and provide basic information for water quality management. In the water quality parameters of Saemangeum Lake, water temperature and total phosphorous content were correlated, and salt, total nitrogen content, pH, and chemical oxygen demand were significantly correlated. Other parameters showed a low correlation. The spatial principal component analysis of Saemangeum Lake showed the characteristics of its four zones. The mid-to-downstream section of the river affected by freshwater inflow showed a high nutrient salt concentration, and the deep-water section of the drainage gate and the lake affected by seawater showed a high salt concentration. Two types of water qualities were observed in the intermediate water area where river water and outer sea water were mixed: waters with relatively low salt and high chemical oxygen demand, and waters with relatively low salt and high pH concentration. In the principal component analysis by time, the water quality was divided into four groups based on the observation month. Group I occurred during May and June in late spring and early summer, Group II was in early spring (March-April) and late autumn (November-December), Group III was in winter (January-February), and Group IV was in summer (July-October) during high temperatures. The water quality characteristics of Saemangeum Lake were found to be affected by the inflow of the upper Mangyeong and Dongjin rivers, and the seawater through the Garuk and Shinshi gates installed in the Saemangeum Embankment. In order to achieve the target water quality of Saemangeum Lake, it is necessary to establish water quality management measures for Saemangeum Lake along with pollution source management measures in the upper basin.

• Korean Journal of Environmental Biology
• /
• v.37 no.3
• /
• pp.406-425
• /
• 2019

To observe the seasonal fluctuation of the meiobenthic fauna community around the coastal area of Jeju island, 20 stations were selected and seasonal surveys were conducted. Three-replicate meiobenthic samples were collected from each station in April, July, and November 2017; February, May, August, and November 2018; and February in 2019, in a total of eight months from 2017 to 2019. The total density of meiobenthos at each station ranged from 733 to 2,505 ind. 10 cm^-2. The month in which the highest habitat density appeared in most stations was April 2017 and the month in which the lowest habitat density was seen was February 2019. Nematodes were the most dominant faunal group among the representative 13 meiofaunal groups at all stations. The subdominant groups were benthic harpacticoid copepods and nauplius. The nematode/copepod (N/C) ratio, reflecting the health indices within the ecosystem, varied from 0.02 to 87.40 over the entire season and the average station values ranged from 2.00 to 16.80. The lowest N/C ratio value was found in April 2017 (0.02) and the highest N/C ratio was found at Station 11 in February 2019, which was 87.40, indicating the highest level of pollution. Seasonal and regional meiobenthos community structure similarity was divided into three groups through group analysis and multi-dimensional scaling (MDS) analysis, which showed that the meiobenthos community structure was affected by seasonal variations, rather than by regional differences.

• Journal of the Korean earth science society
• /
• v.22 no.3
• /
• pp.237-247
• /
• 2001

The concentrations of gaseous mercury (Hg) determined between two different time periods of the late 1980s and the late 1990s were compared to account for the effects of changes between source/sink relationships of atmospheric Hg in an urban area. The Hg concentration levels were different remarkably between the two time periods due possibly to changes in source/sink relationships. The results showed that the Hg levels in the former period were measured to be 14.4${\pm}$9.56ngm$^{-3}$ (N = 2714), whereas those of the latter period were characterized by approximately three-fold decreased values of 5.34${\pm}$3.92 ngm$^{-3}$ (N=2576). Using two independent measurement data sets, we examined the patterns of Hg distribution at different time scales. When analyzed over 24 hour scale, these data sets exhibited two distinctive distribution patterns. The former period showed enhanced concentration levels during daytime, while the latter period showed relative depletion during daytime. The patterns of the two data sets were also examined over seasonal scale. The results of two different time periods consistently showed the occurrences of maximum seasonal values during winter. The former period was characterized by seasonal patterns of fuel consumption with excessive Hg levels during winter. Conversely, no distinctive trend was apparent for the latter period with slight changes in concentration levels across seasons. In order to analyze the factors affecting Hg distributions between two different periods, we conducted both correlation and factor analysis on both all data sets and on seasonally divided data groups. The results of these analyses consistently indicate that the Hg concentration levels for two different time periods are regulated by distinctive source processes that are characteristic of each period.

• Spatial Information Research
• /
• v.20 no.5
• /
• pp.1-13
• /
• 2012

This study intends to evaluate the seasonal flow direction of carbon dioxide in Northeast Asia by using GOSAT, the first Greenhouse Observing SATellite, in an attempt to overcome costly, laborious and time consuming ground observation which has been frequently pointed out in existing studies. For this purpose, missing values were supplemented by applying the Kriging interpolation and the overall flow direction of carbon dioxide was determined through anisotoropy semi-variogram. As a result, it was found that the overall spatial distribution of carbon dioxide in Northeast Asia varies depending on the latitude, and that carbon dioxide mainly flows southeast or east in spring, autumn and winter, but northeast or north in summer. Similar to the flow of monsoons in Northeast Asia, these results show that carbon dioxide flows mainly from the west to the east, which proves that carbon dioxide discharged from China is influencing even the Korean Peninsula and Japan. However, as the flow of carbon dioxide varies depending on a variety of factors such as artificial sources, plant respiration, and the absorption and discharge of the ocean, follow-up studies are requested to evaluate such variables and the correlations.

• Proceedings of the Korean Institute of Landscape Architecture Conference
• /
• 2017.10a
• /
• pp.147-149
• /
• 2017

경수 용기재배는 뿌리분의 손상 없이 식재를 할 수 있어 이식 후 활착이 용이하고, 식재시기의 계절적 제약을 적게 받아 부적기 이식 시 하자를 현저히 줄일 수 있다. 용기재배 시 용기 내 토양온도는 토양의 물리화학반응과 식물의 생육 및 물과 양분의 흡수에 영향을 주는 중요한 토양환경요소의 하나이다. 목본성 식물 용기재배의 경우 제한된 근권부의 토양이 외부기온에 의해 불안정할 수 밖에 없다. 재배용기의 유형에 따른 지온의 변화를 측정한 결과 지중재배형의 용기가 단열성능이 큰 것으로 나타났다. 지상재배 방식의 용기 중에서는 Bag in Pot-루트 스커트 형의 용기가 단열성능이 큰 것으로 나타났으며, 이는 지중재배방식의 용기와 유사한 용기 내 지온 안정화 정도를 보이는 것으로 나타났다. 향후 후속 연구에서는 본 연구를 토대로 디자인 개발된 용기의 시제품을 제작하여 테스트하고, 재배농가에 적용가능성을 검토하고자 한다.

• 대한예방의학회:학술대회논문집
• /
• 2005.10a
• /
• pp.362-362
• /
• 2005

• Korean Journal of Microbiology
• /
• v.29 no.5
• /
• pp.339-343
• /
• 1991

Heterotrophic activity, total bacteria and salinity were determined seasonally in the estuary of Naktong River over half tidal cycle. Heterotrophic activity was determined by the uptake of [U- $^{14}$ C]glucose. Heterotrophic activity fluctuated with the tides and was decreased as salinity increased. Teh great activity occurred near low ebb tide at all seasons except summer. The main environmental factor affecting hetreotrophic activity was the salinity rather than water temperature in the estuary of Naktong River. In order to estimate the effect of salt, salt was added to estuarine water. Vmax for glucose of salt-added water was 17% and 77% of original estuarine water at station 1 and 2 respectively and slight increase was observed at station 3. Respiration rate and Kt+Sn for glucose of salt-added sample increased at all 3 stations. The increase of the Kt value implies the reduced affinity of bacterial population for glucose. The effects of salinity on the heterotrophic activity were more extensive in the upper region of estuary than at the mouth.

• Proceedings of the Korean Society for Agricultural Machinery Conference
• /
• 2002.07a
• /
• pp.169-175
• /
• 2002

저장 중 벼의 품질에 영향을 주는 해충 및 미생물의 발생과 성장속도는 곡온과 함수율이 가장 중요한 요인이다. 곡온은 기온의 계절적 변화에 따라 변하게 되며 저장고내의 위치에 따라 다르게 분포된다. 이러한 불 균일한 온도분포는 자연 대류현상을 유발하고 수분이동을 발생시켜, 함수율 증가와 응축현상을 초래하여 벼의 품질을 손상시키게 된다(Keum and Kim, 1991). 해충의 번식은 온도와 매우 밀접한 관계가 있는데 15$^{\circ}C$이하일 때는 매우 느리거나 나타나지 않고, 4$0^{\circ}C$이상일 때는 대개 생존할 수 없다. 그러나, 3$0^{\circ}C$에서는 최대로 번식하게 된다(Chang et al., 1993). (중략)

• Korean Management Science Review
• /
• v.1
• /
• pp.68-80
• /
• 1984

Box-Jenkins 시계열 분석법은 변수에 관한 정보가 부족하거나 너무 많은 변수가 영향을 미치고 있는 경우에도 과학적인 예측치를 구할 수 있는 단기예측 방법이다. Box-Jenkins 모형은 자동회귀 모형(Autoregressive Model), 이동평균 모형 (Moving average Model), 계절적 시계열 모형을 통합한 일반적인 모형이기 때문에 특별한 불안정성을 보이지 않는 경우에는 모두 모형화 할 수 있으며, 모형에 관계된 계수의 수를 최소화 하면서 만족스러운 모형을 찾을 수 있다. Box-Jenkins예측방법은 모형선정, 매개변수추정, 적합성 검정의 3단계를 반복으로 수행함으로써 최적모형에 이르게 하게 하고 있기 때문에 최소의 가능한 모형으로부터 시작하여 부적당한 부분을 제거시켜 나감으로써 시행착오의 과정을 최소화 할 수 있다. 일반 사용자가 Box-Jenkins 시계열 분석법을 쉽게 사용할 수 있도록 Box-Jenkins Package가 개발되었으며 여기서는 KAIST 전산 개발 센터에 설치된 Package를 소개하고 그 사용예를 보였다.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.6 no.3
• /
• pp.298-308
• /
• 1994

Ocean circulation in the Northeast Pacific Ocean is simulated using a high-resolution primitive equation numerical model with realistic bottom topography. The goal is to explain better the details of observed interannual variability of the circulation in the Gulf of Alaska. Our numerical model suggests that there is no seasonal shift in the Alaska gyre and that the interannual variability. reported earlier, is most likely the result of embedded mesoscale eddies in the dynamic topography. Such eddies have been observed in hydrographic. satellite-tracked drifters and altimeter data from the Gulf of Alaska.