• 한국농공학회논문집
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• 제60권2호
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• pp.121-132
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• 2018

Along with climate change, it is reported that the extreme climate events such as severe drought could cause difficulties of agricultural water supply. To minimize such damages, it is necessary to secure the agricultural water resources by using or saving the amount of irrigation water efficiently. The objectives of this study were to develop paddy water management scenarios and to evaluate their effectiveness on water saving. Three water management scenarios (a) deep irrigation with ponding depth of 20~80 mm (control, CT), (b) no/intermittent irrigation until paddy cracks (water management A, WM-A), and (c) intermittent irrigation with ponding depth under 20 mm (water management B, WM-B) were developed. Water saving effects were analyzed using monitored data from experimental paddy fields, and agricultural water supply was analyzed on a reservoir-scale using MASA model. The observed irrigation amounts were reduced by 21 % and 17 % for WM-A and WM-B compared to CT, respectively, and mainly occurred by the increase of effective rainfall. The simulation results showed that water management scenarios could reduce irrigation by 21~51 % and total inflow by 10~24 % compared to CT. The long-term simulated water level change of agricultural reservoir resulted in the decrease of dead level occurrence for WM-A and WM-B. The study results showed that WT-A and WT-B have more benefit than CT in the aspect of agricultural reservoir water supply.

• 산업경영시스템학회지
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• 제21권48호
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• pp.133-144
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• 1998

International capital movement has made progress at global liberalization of finance and foreign exchange, international monetary norm changing into floating exchange rate system, easiness of collection of information and trade at improvement of information communication technology from early of 1970's. Results of empirical test for relation between foreign exchange rate or various determination factors of foreign exchange rate and interest rate are followed by next sentences. First, according to relation between foreign exchange rate and interest rate, correlation for each of variables after OECD entrance is increased. But, long-term & short-term interest rate is affected by Hanbo & Kia's bankruptcy, continuous large scale corporates bankruptcy and crisis of foreign exchange. Therefore, financial instability is occured. If portfolio investment fund has been inflow as it is mollified by continuous shortage of foreign exchange and fall of country's credit rating, it is expected to have positive effect for long-term & short-term interest rate from appreciation of won against dollar. Second, results from relation between determination factor of foreign exchange rate and interest rate are followed by next sentences. If surplus of current account and goods account is continued, yield of corporate bond is to be stable. But, margin of surplus is expected to diminish after second quarter 98, and difference between external and domestic interest (after adjusting foreign exchange rate) is to be diminished. And if net inflows of foreign investor's fund (stock and bond) is diminished, it is to have negative effect for yield of corporate bond. According to foreign investor's investment movement of previous years, hedge fund were stayed at least during two years in Mexico. It means that sudden capital outflow is not to be happened at Korea. But if external factors from depreciation of yen and China's renminbi are instable, interest rate is expected to increase from capital's outflows. Third, if it is to decrease instability of foreign exchange rate from increase in surplus of future current account, credit rating's upwardness, stability of yen and renminbi, foreign exchange rate is expected to be stable. It is expected to have continuous stability from short-term interest rate to long-term interest rate in this empirical test.

• 한국환경과학회지
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• 제20권6호
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• pp.711-719
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• 2011

This study was conducted to estimate the distribution characteristics and budget of organic matter in the Lake Hapcheon. In the dry season, the concentration ranges of organic carbons were similar, but in the rainfall season, it showed about double concentrations. Changes of vertical water quality in the lake, there were no big differences with the concentration by the depth. However, it tends to be relatively high on the surface, a little low on the mid-depth and high in the lake bottom. DOC rate at TOC, it was lower than POC rate at inflow and DOC rate was higher than POC rate in the lake and discharging water. R-DOC accounted for more 80% of DOC rate in all investigated areas, therefore we judge that this R-DOC is to increase the organic carbon pollution gradually. As the result of the calculated organic carbon budget in the Lake Hapcheon, the amount of allochthonous, autochthonous and release were 3,552, 3,288, 228 tonC/year, respectively. the amount of discharge, decomposition and sedimentation were 504, 1,344, 5,520 tonC/year, respectively. According to this investigation, the changed amount of organic matter in the Lake Hapcheon recorded -300 tonC/year with the increase of 7,068 tonC/year and the decrease of 7,368 tonC/year.

• Journal of the korean society of oceanography
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• 제35권2호
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• pp.109-123
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• 2000

Depositional processes of fine-grained sediments were investigated on the basis of sediment transport vector analysis and identification of benthic foraminiferal assemblages in Yoja Bay, southern coast of Korea. The bay is a semi-enclosed embayment where extensive mud flats occur with a width up to about 4 km. Most surface sediments are poorly sorted (sorting values: 1.9-3.0 ${\phi}$) mud and silt (mean grain size: 6.0-8.7 ${\phi}$), except for the tidal inlets with basement rocks locally exposed. Grain-size distribution shows a fining tendency toward the basin center near the Yoja Island, implying a possible existence of turbidity maximum and relatively rapid settling of fine-grained sediments. The agglutinated foraminiferal taxa are dominant in the inner bay and decrease in abundance toward the mouth of the bay. Species diversities are higher in the outer bay, due to mixing of the offshore faunas with those of the bay. Four groups of benthic foraminiferal assemblages, identified by cluster analysis, represent the bay. Biofacies I and ll with relatively lower diversities are dominated by Ammobaculites exiguus and Ammonia beccarii, suggestive of influx of fresh water. In contrast, biofacies III and IV with relatively higher diversities include increased amounts of calcareous genus Elphidium and Quinquelocuzina, accounting for strong influence of sea water from the offshore. The fluvial discharge in summer floods appears to develop a bay-wide, clockwise lateral circulation in Yoja Bay, a typical of well-mixed estuaries. Accordingly, the foraminiferal assemblages of the surface sediments well show a sign of this circulation. The dominant inflow of the offshore water into the western part of the bay has resulted in more extensive muddy tidal flats compared to the eastern narrower counterpart.

• 한국전산유체공학회지
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• 제22권1호
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• pp.15-25
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• 2017

Swirl flow is often found in proximal coronary arteries, because the aortic valves can induce swirl flows in the coronary artery due to vortex formation. In addition, the curvature and tortuosity of arterial configurations can also produce swirl flows. The present study was performed to investigate fractional flow reserve alterations in a post-stenotic distal part due to the presence of pre-stenotic swirl flow by computational fluid dynamics analysis for virtual stenotic models by quantifying fractional flow reserve(FFR). Simplified stenotic coronary models were divided into those with and without pre-stenotic swirl flow. Various degrees of virtual stenosis were grouped into three grades: mild, moderate, and severe, with degree of stenosis of 0 ~ 40%, 50 ~ 60%, and 70 ~ 90%, respectively. In this study, three-dimensional computational hemodynamic simulations were performed under hyperemic conditions in virtual stenotic coronary models by coupling with a zero-dimensional lumped parameter model. The results showed that the influence of pre-stenotic swirl inflow is dominant on FFR alteration in mild stenosis, whereas stenosis is dominant on FFR alteration in moderate/severe stenosis. The decrease in FFR caused by swirl flow is more significant in mild stenosis than moderate/severe stenosis. Biomechanical modeling is useful for clinicians to provide insight for medical intervention strategies. This hemodynamic-based parameter study could play a critical role in the development of a non-invasive imaging-based strategy-support system for percutaneous transluminal angioplasty in cases of mild/moderate stenosis.

• 한국물환경학회지
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• 제20권5호
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• pp.422-431
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• 2004

Water quality modeling was performed for the purpose of diagnosis and prediction of water quality in Gyoung Choen reservoir, using EUTR05/WASP Build model. WASP Builder is capable of visual display in window and it has an advantage of updating and modification for data. Field data of 1992, Spring, Summer, and Fall, were used to calibrate model and these results were validated using data of 2000, Spring, Summer, and Fall. The reservoir was divided into 4 epilimnion segments. Water quality system for modeling were consist of BOD, Chlorophyll-a, DO, $NH_3-N$, $NO_3-N$, T-N, $PO_4-P$, T-P. The results of water quality modelling using EUTR05/WASP Builder, a range of the Correlation for calibration of BOD, T-N, T-P, and Chlorophyll-a according to three seasons are 0.63~0.90, 0.81~0.97, 0.75~0.98, and 0.77~0.98 respectively. And the correlation between simulated and observed values for verification of BOD, T-N, T-P, and Chlorophyll-a according to three seasons are 0.93, 0.94, 0.81, and 0.80 respectively. Among the pollutant sources for a basin of the Gyoung Choen reservoir, generated amount of livestock is the highest and BOD, T-N, T-P of generated loading percentage are 94%, 81%, and 95%. So, we suppose that inflow load amount will decrease 50% and increase 50% only livestock about current load amount. If increasing load amount of livestock 50% in segment 2 and 3, BOD, T-N, and T-P simulated increasing to range of $0.02~0.15mg/{\ell}$, $0.029~0.08mg/{\ell}$, $0.011~0.029mg/{\ell}$ in comparison with current water quality

• 한국수자원학회논문집
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• 제51권4호
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• pp.355-369
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• 2018

기후변화 영향으로 미래의 유출량은 변화할 것이다. 미래 유출량의 변화는 수자원시설에 유입량을 변화시켜 발전량에 영향을 미친다. 본 연구는 기후변화로 인한 유출변화에 따른 북한 수자원시설 발전량을 평가하였다. 수자원시설에 대한 발전량은 물의 에너지에 의해 수차 발전기를 회전시켜 전력을 발생시킨다. 즉, 물의 위치에너지를 운동에너지로 바꾸고 운동에너지를 다시 전기에너지로 변화시키는 것이다. 본 연구의 평가 결과, 북한 수자원시설 발전량은 현재보다 2011년부터 2040년까지 감소하였고, 2041년부터 2100년까지는 증가하였다. 또한, 기존 북한 수자원시설의 발전량은 미래에 감소하거나 현재와 비슷하게 나타났다. 신규 북한 수자원시설의 발전량은 단기적으로는 감소하지만, 중장기 미래에는 증가하는 것으로 나타났다. 기존 북한 수자원시설은 기후변화 영향에 취약하고, 신규 북한 수자원시설은 기후변화 영향에 유리하게 입지하고 있는 것으로 판단된다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제20권3호
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• pp.41-50
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• 2015

Hydrogeologic environment of the Mega City such as Seoul, suffers from rapid changes caused by urbanization, construction of underground subway or buildings, and contaminant loading by diverse anthropogenic activities. Understanding the present condition of groundwater environment and water budget is necessary to prevent natural and manmade disasters and to prepare for sustainable water resource management of urban environment. In this study, regional groundwater flow and water budget status of Seoul was analyzed using numerical simulation. Modeling result indicated that groundwater level distribution of Seoul generally followed the topography, but the significant decreases in groundwater level were observed around the subway network. Steady-state water balance analysis showed groundwater recharge by rainfall and leakage from the water supply network was about 550,495 m³/day. Surface water inflow and baseflow rate via Han River and major streams accounted for 799,689 m³/day and 1,103,906 m³/day, respectively. Groundwater usage was 60,945 m³/day, and the total groundwater leakage along the subway lines amounted to 114,746 m³/day. Modeling results revealed that the subway could decrease net groundwater baseflow by 40%. Our study result demonstrated that the subway system can have a significant influence on the groundwater environment of Seoul.

• 환경영향평가
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• 제21권2호
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• pp.229-238
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• 2012

This research was to examine the physiochemical factors and the attached diatoms of ecological wetland in Paju from August 2010 to May 2011. As a result of physicohemical water quality assessment, the water temperature did not fluctuate much due to ample riparian vegetation and aquatic plants growing at the site. Due to the effect of Han River Estuary, site 4, 5 and 6 had high electricity conductivity. The BOD concentration was high at site 2, 3, and 4 caused by decrease in water quantity and inflow of polluted water. At all sites, T-N and T-P concentrations ranged from eutrophic to hypertrophic status. At the downstream, the T-N and T-P concentrations decreased by inhabiting aquatic plant. Total of 98 taxa of attached diatoms were found. As for dominant taxa, Achnanthes convergens, A. minutissima, Gomphonema gracile, G. parvulum, Melosira varians, Navicula seminulum, N. minima, N. pseudolanceolata, Nitzschia amphibia, N. palea, Surirella minuta and Synedra ulna var. fragilariodes appeared. The result of biological assessment of water quality rated the sites B(suboptimal)~D(poor) during seasons of low water temperature, Fall and Winter, with DAIpo ranging 24.1~68.2 and TDI of 48.4~85.6. During Spring and Summer, all sites were rated D(poor) with DAIpo lower than or equal to 40, and TDI above or equal to 70. The biological assessment of water quality at the research site showed inferior TDI result compared to that of DAIpo.

• 한국수정란이식학회지
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• 제33권2호
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• pp.61-68
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• 2018

The major focus of this study is to analyze the expression of bovine MMPs and to monitor their activity during the estrus cycle and pregnancy. During pregnancy, MMP-2 expression was detectable around 30 days but became insignificant by 60 days, then started to increase again around 90 days and reached the maximum at 250 days. The activity of MMP-2 protein changed in accordance with its expression level. As expected, the level of TIMP-2 exhibited a reverse pattern. About MMP-9, high level expression was observed as early as 30 days and gradually increase until 90 days. Then started to decrease after 250 days. Again, the sites of MMP-9 expression were similar to those of MMP-2. On the other hand, expression of TIMP-3 remained low until 90 days but showed a small and temporal increase around 250 days. In summary, expression of different MMPs were differentially regulated during estrus cycle and pregnancy. While the expression of MMP-2 was high in estrus cycle, MMP-9 slowly takes over with the progression of pregnancy. These results indicated that the luteal tissue perform distinct functions during pregnancy and estrus. Perhaps the activity of MMP-2 is required for the structural remodeling of luteum, resulting the suppression of P4 inflow from blood. On the other hand, steady maintenance of MMP-9 throughout luteal development is important for the activation of cell proliferation, maturation and angiogenesis.