• The Journal of Engineering Geology
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• v.15 no.3
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• pp.303-307
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• 2005

Severe drawdown of Groundwater level(CWL) is observed from the analysis of the relationship between precipitation and CWL data during dry seasons in Ssangchun watershed. For Ssangchun watershed, the correlation was the strongest when we apply 70 day Moving Average(MA) for Groundwater dam Operation Index(COI) calculation. To determine the critical infiltration, which is the spatially averaged maximum daily infiltration, a certain value is fixed as the maximum infiltration and precipitation data is modified. COI is recalculated after the data modification and the correlation between COI and GWL is checked. The critical infiltration is determined when the best correlation is obtained after we repeat the above procedure with different fixed values. The critical infiltration is 40m for Ssangchun watershed. The correlation between CWL and COI is higher when we consider critical infiltration than we neglected it.

• Journal of The Korean Society of Grassland and Forage Science
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• v.13 no.2
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• pp.93-98
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• 1993

To determine the effects of potassium($K_2O$) fertilization level(0, 100, 200 and 300 kg/ha/year) on the growth, dry matter(DM) yield, nutritive value and nitrate nitrogen($NO_3$-N) concentration of grasses grown under shading condition, this experiment was carried out in Grassland Div., LES, 1989. The plants were sampled on different growing seasons (spring, summer and autumn) and growth stages (grazing and soiling), respectively. Shade was controlled artificially ca. 45-50%, and the level of nitrogen fertilization was 200 kg/ha/year in all treatments. Higher DM was produced in spring 1, 453 kg at grazing and 2, 364 kg/ha at soiling stage, and DM production was increased with increasing level of $K_2O$. In this experiment, the optimum amount of $K_2O$ fertilizer was 200 kg/ha. The neutral detergent fiber, acid detergent fiber, DM digestibility, and relative feed value of grasses were not affected by $K_2O$ fertilization, regardless of growing season and growth stage. The $NO_3$-N concentration of grasses grown in spring was very low (ca. 1.0%), regardless of growth stage and $K_2O$ level. However, $NO_3$-N concentration was very high in summer and autumn season, also $NO_3$-N was decreased significantly with increasing level of $K_2O$ fertilization (P<0.05). Application of $K_2O$ fertilizer, therefore, is thoughs to be desirable for reducing $NO_3$-N concentration of grasses, especially in summer and autumn season. So annual split fertilization of $K_2O$ could be recommended on woodland pasture.

• Journal of Korean Society on Water Environment
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• v.28 no.1
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• pp.10-17
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• 2012

The middle and lower reaches of the Kum River system become stagnant in dry seasons with florishing of phytoplankton. In this study primary productivity of phytoplankton were measured by the C-14 uptake method and the P-I model method at seven main stream sites of the Kum River from the Daechung Dam outet to the river mouth. Nutrients (TN, TP, DIP, TIN) concentrations were measured in the mainstream and tributaries and compared with the variation of assimilation number. The range of primary productivity was $40{\sim}4,558mgC{\cdot}m^{-2}{\cdot}day^{-1}$ and it was higher than those of lentic ecosystems in Korea. Average TN and TP were $4.1mgN{\cdot}L^{-1}$, $70.6mgP{\cdot}m^{-3}$, respectively. Tributaries showed higher nutrient concentrations than the main stream. After two major tributaries merged with the discharging water of the Daechung Dam phyotplankton biomass and productivity increased drastically and remained at the similar eutrophic level through the downstream reach to the river mouth. Both dissolved phosphorus and nitrogen concentrations showed positive correlation with assimilation number of phytoplankton. In conclusion phytoplankton productivity is at the level of eutrophic water and it was higher than usual lentic habitats. Nutrient concentrations are critical factors in controlling productivity in the lower reach of the Kum River.

• Journal of Wetlands Research
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• v.11 no.3
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• pp.89-103
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• 2009

The Philippines is abundant with rich natural resources such as water. Because of rapid urbanization in the country, most of the water bodies are polluted as a result of domestic, agricultural and industrial activities. The Environmental Management Bureau (EMB) is the main government arm responsible for monitoring and inspection of affected water bodies. Only water bodies with at least four sampling events during dry and wet seasons were included in the assessment of water bodies that passed the DAO 90-34 water quality criteria. Water bodies were monitored for dissolved oxygen (DO), biochemical oxygen demand (BOD), total suspended solids (TSS), and total dissolved solids (TDS), heavy metals, fecal coliform contamination and nitrates. High pollutant concentrations from domestic, agricultural, industrial and nonpoint sources were observed from monitoring events due to inadequate sewage services and treatment facilities in the country. The objective of this paper was to present and evaluate the quality of the water bodies in the Philippines.

• Journal of Ecology and Environment
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• v.33 no.1
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• pp.59-65
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• 2010

Because seagrass production significantly contributes to the biodiversity and production of coastal and estuarine ecosystems, accurate estimation of seagrass productivity is a critical step toward understanding the ecological roles of seagrass in these ecosystems. To develop an accurate and effective method of measuring seagrass productivity, we estimated leaf productivity of eelgrass (Zostera marina) on the southern coast of Korea using three methods, the conventional leaf marking method, the elongation-mass method (Short '87 method), and the plastochrone method. In each season, shoots were pierced through the bundle sheath using a hypodermic needle and were collected after 2-4 weeks had elapsed to estimate their productivity. The leaf elongation and the leaf plastochrone intervals varied significantly among seasons. On an annual basis, the conventional leaf marking method showed the lowest leaf productivity estimates compared to the elongation-mass method and the plastochrone method, suggesting that the conventional leaf marking method underestimated leaf productivity as it ignored leaf maturation processes and new leaf growth within the sheath. Since the elongation-mass method considered leaf maturation processes, this method produced higher leaf productivity estimates than the conventional leaf marking method. On an annual basis, the plastochrone method produced the highest leaf productivity estimates. Below-ground productivity, which can be easily estimated using the plastochrone method, ranged between 3.29 and 5.73 (mg dry weight $shoot^{-1}\;day^{-1}$) and accounted for about 17.8% to 30.3% of total productivity. Because of the high contributions of below-ground productivity to total seagrass production, we suggest that the plastochrone method is an effective and simple technique for assessing both above- and below-ground productivities.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.2
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• pp.955-961
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• 2013

This study aimed for the scientific approach of Korean traditional house, so called Hanok, by analyses of structural elements and thermal environmental performance. Hanok is a very unique vernacular architectural style of the Middle East Asia that fits with climate conditions of the Korean Peninsular, designed to withstand high temperature and humidity in summer and cold and dry in winter seasons. In order to evaluate thermal environment of Hanok, its sectional structure such as floor, wall, roof structure and Ondol which is Korean traditional floor heating system, was built in 3D, as well as heat transfer mechanism of its composing elements was analyzed through 3 dimensional steady state analysis. The results of the thermal environmental performance of Hanok will be used as a basic datum of design guidelines for accomplishing ecologic housing fitted with local climate.

• Atmosphere
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• v.28 no.1
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• pp.85-97
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• 2018

This study evaluates the performance of the Weather Research and Forecasting (WRF) model in reproducing the present-day (1981~2005) precipitation over Far East Asia and South Korea. The WRF model is configured with 25-km horizontal resolution within the context of the COordinated Regional climate Downscaling Experiment (CORDEX) - East Asia Phase 2. The initial and lateral boundary forcing for the WRF simulation are derived from European Centre for Medium-Range Weather Forecast Interim reanalysis. According to our results, WRF model shows a reasonable performance to reproduce the features of precipitation, such as seasonal climatology, annual and inter-annual variabilities, seasonal march of monsoon rainfall and extreme precipitation. In spite of such model's ability to simulate major features of precipitation, systematic biases are found in the downscaled simulation in some sub-regions and seasons. In particular, the WRF model systematically tends to overestimate (underestimate) precipitation over Far East Asia (South Korea), and relatively large biases are evident during the summer season. In terms of inter-annual variability, WRF shows an overall smaller (larger) standard deviation in the Far East Asia (South Korea) compared to observation. In addition, WRF overestimates the frequency and amount of weak precipitation, but underestimates those of heavy precipitation. Also, the number of wet days, the precipitation intensity above the 95 percentile, and consecutive wet days (consecutive dry days) are overestimated (underestimated) over eastern (western) part of South Korea. The results of this study can be used as reference data when providing information about projections of fine-scale climate change over East Asia.

• Environmental Engineering Research
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• v.16 no.3
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• pp.121-129
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• 2011

The completely mixed flow and plug flow (CAP) water quality model was developed for streams with discontinuous flows, a condition that often occurs in low base flow streams with in-stream hydraulic structures, especially during dry seasons. To consider the distinct physical properties of each reach effectively, the CAP model stream network can include both plug flow (PF) segments and completely mixed flow (CMF) segments. Many existing water quality models are capable of simulating various constituents and their interactions in surface water bodies. More complicated models do not necessarily produce more accurate results because of problems in data availability and uncertainties. Due to the complicated and even random nature of environmental forcing functions, it is not possible to construct an ideal model for every situation. Therefore, at present, many governmental level water quality standards and decisions are still based on lumped constituents, such as the carbonaceous biochemical oxygen demand (CBOD), the total nitrogen (TN) or the total phosphorus (TP). In these cases, a model dedicated to predicting the target concentration based on available data may provide as equally accurate results as a general purpose model. The CAP model assumes that its water quality constituents are independent of each other and thus can be applied for any constituent in waters that follow first order reaction kinetics. The CAP model was applied to the Geum River in Korea and tested for CBOD, TN, and TP concentrations. A trial and error method was used for parameter calibration using the field data. The results agreed well with QUAL2EU model predictions.

• Journal of The Korean Society of Grassland and Forage Science
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• v.16 no.1
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• pp.61-68
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• 1996

Hehage production, botanical composition and soil chemical characteristics were investigated Ween new pastures and old pastures during grazing seasons from May 1993 to October 1994, to find out the condition of pastures grazed by horses on Chdu. Dry matter yields between new pastures and old pastures were 8,757kglha and 7,486kglha respectively. Plant heights of new pastures were 17.4cm. compared with those of old pastures of 12.lcm. The botanical composition of new pastures was composed of grasses about 402, legumes 7~14%, others 18-30% and dead materials 18~ 25%. whiie there were grasses 12%, legumes 3~7%, others 65% and dead materials 15% in old pastures. The contents of crude protein, phosphoms and sodium were lower in old pastures(l3.30, 0.24 and 0.10% respectively) than those in new pastures(l5.47, 0.28 and 0.14% respectively). There was no difference in ADF, NDF, Ca, Mg and K content between the 2 kinds of pastures. The chemical characteristics of the 2 kinds of pastures was shown to be similar, except available phosphorus, comparing 8.18ppm in old pastures with 84.43ppm in new pastures. Although the herbage yield and the soil characteristics of old pastures were lower than those of new pastures, we suppose that the old pastures would be improved, if taken good care of by methods such as oversowing and sometimes applying fertilizer.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.8
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• pp.1098-1106
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• 2004

In a split-unit design, 12 Javan rusa (Cervus timorensis russa) stags (6 castrated and 6 entire) were used to investigate seasonal (winter, spring and summer) effects on intake, digestibility of food constituents, volatile fatty acid profile, and nitrogen retention, when given lucerne (Medicago sativa) or rhodes grass (Chloris guyana) hays. Entire stags ate 9% more dry matter (DM) than castrates (p<0.05). Both castrated and entire stags exhibited seasonal changes in DM intake, these being higher (p<0.05) in winter (62.3 g/kg $W^{0.75}$) than spring (56.9 g/kg $W^{0.75}$) or summer (55.3 g/kg $W^{0.75}$). Intakes of lucerne hay (211 g protein/kg DM) were significantly higher than of rhodes grass hay (49 g protein/kg DM) in all seasons (p<0.05). Digestibilities of DM (0.58), neutral detergent fibre (0.59) and acid detergent fibre (0.47) were similar between castrates and entires. DM digestibility was higher (p<0.0001) for lucerne (0.66) than rhodes grass (0.55), and was higher (p<0.05) in winter (0.60) than spring (0.58) or summer (0.57). The ruminal acetate concentrations were higher (p<0.001) in spring than summer (78 and 73 molar % respectively). Apparent digestibility of protein was significantly less (p<0.0001) for rhodes grass (0.37) than lucerne (0.75). N retention was positive for lucerne (15.2 g/d) but negative for rhodes grass (-2.8 g/d) (p<0.0001), and was higher (p<0.001) in summer (12.0 g/d) than spring (4.3 g/d) or winter (2.4 g/d). The tropical rusa deer exhibits seasonal variations in feed intake, food constituent digestibilities, VFA profile and N retention. Castration did not alter these traits. The results do not support the view that rusa deer can thrive on low-quality pastures. The productivity and commercial exploitation of rusa deer could be optimised if they are given high-protein feed during spring and summer.