• Journal of Wetlands Research
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• v.17 no.4
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• pp.339-347
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• 2015

Differences in characteristics of flora and environmental factors of geomorphology, hydrology, water quality and soil were investigated in the shoreline of total 35 reservoirs according to their usages of waterpower generation, agricultural water supply, residential and industrial water supply and flood control in Korea. The number of plant species, floral structure and characteristics of species traits in the shoreline of reservoirs were different according to their usage. From the results of stepwise regression analysis, the total number of vascular plant species was increased at the environment of the higher flood frequency at the median water level and the longer exposure duration of the shoreline. The results of principal coordinates analysis and cluster analysis showed that the shoreline flora was classified as the 3 types of 1) flood control and residential and industrial water supply, 2) agricultural water supply and 3) waterpower generation reservoirs. The water level fluctuation, flood frequency at the median water level, lake water quality index and exposure duration of the shoreline were selected as important environmental factors affected on the characteristics of shoreline flora. The species richness of total flora and hydrophytes, especially submerged macrophytes, were much higher in the reservoirs for the purpose of the waterpower generation in which mesotrophic water quality and stable water levels were maintained. Annual or biennial ruderals were established on the ephemeral drawdown zone of flood control, residential and industrial water supply reservoirs which have oligotrophic or mesotrophic water quality and wide range of water level fluctuation. The floating hydrophytes were differentially dominated in the littoral zones of the agricultural water supply reservoirs with a mesotrophic or eutrophic water quality and a medium water level fluctuation. In conclusion environmental factors related to water level fluctuation and water quality were different and then the floral characteristics of shoreline were distinguishable according to usage of Korean reservoirs.

• Ocean and Polar Research
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• v.34 no.4
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• pp.395-401
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• 2012

Ten-year AVHRR sea surface temperature data obtained in the Yellow Sea are put into EOF analyses. Temperature variation is predominated by the first mode which is associated with the seasonal fluctuation of temperature with annual range decreasing with the bottom depth. Since such a strong annual signal may mask the upwind or downwind flows occurring intermittently during the winter, only the data obtained during this season are put into EOF analyses. Every winter shows similar results. The first mode, explaining more than 90% of total variance, appears to be a part of the seasonal variation of temperature mentioned above. In the second mode, the time coefficient is well correlated with northerly winds to which the responses of the trough and shallow coastal areas are opposite to each other. A simple theoretical consideration suggests the following physical explanation: The northerly wind stress anomaly creates an upwind (downwind) flow over the trough (coastal) areas, which then induces a temperature increase (decrease) by advection of heat, and vice versa for the southerly wind stress anomaly. Hence, this paper provides further evidence of the intermittent upwind or downwind flows occurring in the Yellow Sea every winter.

• Journal of the Korean earth science society
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• v.39 no.1
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• pp.1-22
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• 2018

Eight different data sets are examined in order to gain insight into the surface heat flux traits of the East Asian marginal seas. In the case of solar radiation of the East Sea (Japan Sea), Coordinated Ocean-ice Reference Experiments ver. 2 (CORE2) and the Objectively Analyzed Air-Sea Fluxes (OAFlux) are similar to the observed data at meteorological stations. A combination is sought by averaging these as well as the Climate Forecast System Reanalysis (CFSR) and the National Centers for Environmental Prediction (NCEP)-1 data to acquire more accurate surface heat flux for the East Asian marginal seas. According to the Combination Data, the annual averages of net heat flux of the East Sea, Yellow Sea, and East China Sea are -61.84, -22.42, and $-97.54Wm^{-2}$, respectively. The Kuroshio area to the south of Japan and the southern East Sea were found to have the largest upward annual mean net heat flux during winter, at -460- -300 and at $-370--300Wm^{-2}$, respectively. The long-term fluctuation (1984-2004) of the net heat flux shows a trend of increasing transport of heat from the ocean into the atmosphere throughout the study area.

• Korean Journal of Microbiology
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• v.24 no.3
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• pp.308-316
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• 1986

Vertical distribution of heterotrophic bacteria and physico-chemical characteristics were measuted in Kum River estuarine sediments. And interrelationship between heterotrophic bacterka and environmental factors was also studied. The type of sediment of Site 1 was silty clay, and sand at Site 2. Annual pH ranges were between 7.1 and 7.7 in the clay type sediment (Site 1) and 6.9-7.2 in the sand type sediment (Site 2). It was shown that organic matter contents were higher in the clay type sediment than those of sand type sediment. Redox potential values of sediments were decreased rapidly with depth at Site 1, but those of Sete 2 showed vertical fluctuation. Nitrogens(ammonia+amino acid-N, nitrate-N, nitrite-N) and phosphate in the clay type sediment showed higher values than those of sand type sediment. Annual distribution of heterotrophic bacteria were ranged $6.71{\times}10^4$ cells/g dry wt. $-2.50{\times}10^6$ cells/g dry wt. In the clay type sediment and $2.67{\times}10^3$ cells/g dry wt. $-1.94{\times}10^6$ cells/g dry wt. in the sand type sediment. Distribution of proteolytic, lipolytic, and amylolytic bacteria were decreased with the depth and the highest density was found in April and the lowest in January. Bacterial populations in sediments were closely correlated with such environmental factors as pH, redox potential, moisture content, organic matter contents, and inorganic nutrients such as nitrite-N and phosphate-P.

• Korean Journal of Remote Sensing
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• v.28 no.3
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• pp.267-276
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• 2012

Terminal lakes are widely distributed in the arid and semi-arid Gobi of Mongolia, and serves as important water resource for local people and livestock. However, such lakes are subject to great fluctuations in its size depending on climatic conditions and human water utilization. The Orog Lake is one such example that has shown remarkable fluctuation in recent years. In this study, we investigated the temporal changes of Orog Lake surface area by using 16-day MODIS 250 m NDVI products from 2000 to 2010. The results were compared with climate variability represented by monthly precipitation and temperature. Our results show that the Orog Lake gradually shrank for the period from 2000 to 2010, but with a significant range of seasonal and inter-annual variability. The lake area showed considerable seasonal variations, as it expanded in spring and fall, primarily due to snow melt and summer precipitation, respectively. Extreme drought period from 2000 to 2002 triggered the substantial reduction in lake area, leading to dry-up in year 2005, 2006, 2007, and 2009. After dry-up once occurred in 2005, the lake repeated reappearance and disappearance depending on seasonal and annual precipitation. Our findings implicate that the ground water fluctuated around the lake bottom level since 2005. This suggests the highly vulnerable nature of Orog lake, which greatly depends on future precipitation change.

• Journal of the Korean Wood Science and Technology
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• v.21 no.3
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• pp.45-52
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• 1993

Surveyed results on the slope of grain and the twist of sawn lumber of Pinus koraiensis, Larix leptolepis, and Pinus densiflora were summarized as follows: 1. The slope of grain of Pinus koraiensis has a Z-grain in the stem axis. The slope of grain was found to be the lowest at near to the pith and then constantly increased. At the height of 0.2m from the base of stem. a cross section of 35 annual rings was found to have a repeatedly increasing and decreasing slope of grain and then constantly decreased. At the height of 1.2m to 7.2m from the base of stem, the slope of grain increased conspicuously until the 10th annual ring, after which it increased near to the bark with repeatedly increasing and decreasing trends. 2. Pinus densiflora has a S-grain in the stem axis. The lowest slope of grain was found at near to the pith, and the highest in the 10 to 35 annual rings from the pith. 3. Larix leptolepis has a S-grain. At the height of 3.2m from the base of stem, the big fluctuation of the slope of grain was found without any particular trend. 4. The slope of grain and the twist between natural and reforested timber of Pinus koraiensis were found to be almost the same trend in viewpoint of the annual ring. The maximum slope of grain of imported Siberian timber of Pinus koraiensis was found at the 10 annual rings, which was quite similar to that of native species in Korea, but the big difference of the twist was found at 140 annual rings. 5. The twist was little at the mature wood of reforested Pinus koraiensis and Siberians and the duplicated part of mature and juvenile woods of those. On the contrary, the twist was great at the duplicated part of mature and juvenile woods of Pinus koraiensis. 6. The twist of Larix leptolepis showed the S-direction which coincided with that of slope of grain. The twist was greatest at the part of juvenile wood and little at the duplicated part of mature and juvenile woods, and little difference of twist was found between mature and juvenile woods. 7. Siberian larix having a minimum slope of grain showed the lowest twist, and the twist at the duplicated part of mature and juvenile woods showed a middle level of both mature and juvenile woods' portions.

• Economic and Environmental Geology
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• v.54 no.1
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• pp.77-89
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• 2021

In this study, a method has been proposed to improve the performance of hydraulic property estimation model developed by Jeong et al. (2020). In their study, low-dimensional features of the annual groundwater level (GWL) fluctuation patterns extracted based on a Denoising autoencoder (DAE) was used to develop a regression model for predicting hydraulic properties of an aquifer. However, low-dimensional features of the DAE are highly dependent on the precipitation pattern even if the GWL is monitored at the same location, causing uncertainty in hydraulic property estimation of the regression model. To solve the above problem, a process for generating the GWL fluctuation pattern for conditioning the precipitation is proposed based on a conditional variational autoencoder (CVAE). The CVAE trains a statistical relationship between GWL fluctuation and precipitation pattern. The actual GWL and precipitation data monitored on a total of 71 monitoring stations over 10 years in South Korea was applied to validate the effect of using CVAE. As a result, the trained CVAE model reasonably generated GWL fluctuation pattern with the conditioning of various precipitation patterns for all the monitoring locations. Based on the trained CVAE model, the low-dimensional features of the GWL fluctuation pattern without interference of different precipitation patterns were extracted for all monitoring stations, and they were compared to the features extracted based on the DAE. Consequently, it can be confirmed that the statistical consistency of the features extracted using CVAE is improved compared to DAE. Thus, we conclude that the proposed method may be useful in extracting a more accurate feature of GWL fluctuation pattern affected solely by hydraulic characteristics of the aquifer, which would be followed by the improved performance of the previously developed regression model.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2003.11a
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• pp.47-51
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• 2003

In this paper, we compared the thermal environment in the livingroom with panel heating system of Korea and Japan. The houses are two apartments and two single houses in Korea, and two apartments in Japan. The outdoor temperatures, indoor air temperatures, surface temperatures on floor and humidities were measured. The survey to the residents and recording of operation were also collected. The results were as follows.1. The Korean houses are warmer and drier(approximately 23$^{\circ}$C, 38%) than those of Japan.(approximately 20$^{\circ}$C, 57%). And indoor temperaures of Korean apartment are stabie. 2.The residents in Japan put on and off the switches of the heating system frequently.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2000.11a
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• pp.36-39
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• 2000

The Ministry of Construction and Transportation is going to establish 310 groundwater monitoring stations. 154 stations have been established and periodically managed since 1995. Most of stations have two monitoring boreholes which function is to monitor the unconsolidated and bedrock aquifer, and have the automatic monitoring equipment to observe groundwater level, temperature and hydraulic conductivity which are measured four times a day. Especially 44 stations are equipped with the Remote Terminal Unit. MOCT publish "an annual report of Groundwater monitoring stations" every year and everyone can get the monitoring data from Groundwater World web site(http://wamis.kowaco.or.kr/gww/)..kr/gww/).

• Proceedings of the Korean Geotechical Society Conference
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• 2002.03a
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• pp.165-172
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• 2002

We presents an hazard zonation mapping technique in karst terrain and its assessment. From the detailed engineering geological mapping. Controlling factors of sink hole and limestone cave formation were discussed and 4 main hazard factors affecting hazard potential are identified as follows: prerequisite hazard factor(distributions of pre-existing sink holes and cavities), geomorphological hazard factors(slope gradient, vegetation, and drainage pattern etc.) geological hazard factors(lithology, fracture patterns and geological structures etc.) and hydraulic conditions(hydraulic head, annual fluctuation of ground water table and composition of g/w water). From the construction of hazard zonation map along the Jecheon-Maepo area, and vertical cross-sectional hazard zonations specific tunnel site we suggest hazard zonation rating systems.