• Water for future
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• v.8 no.2
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• pp.53-53
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• 1975

한 유역의 수계망조직은 그 유역의 기상학적 및 지상학적 특성의 복합효과에 의하여 형성되는 것이며 유역의 주요수문량인 유량은 이들 하천형태학적 특성에 의하여 큰 영향을 받게된다. 따라서 본 연구에서는 한강유역의 하천형태학적 특성을 양적으로 분석한 후 이들 형태학적 특성을 유역의 유출특성과 상관시켰다. 유출특성으로 선정한 유량은 이수목적을 위한 분석대상이 되는 일 평균 유량과 수질오염통제의 기준이 되는 7일 10년 유량(7-day 10-year low flow)으로서 다음과 같은 절차에 의하여 하천형태학적 특성인자와 상관시켰다.

• Journal of Korea Water Resources Association
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• v.45 no.10
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• pp.969-981
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• 2012

In this study, we analysed hydrologic variability in quantity and onset of annual maximum flow and low flow by impacts of the different phases of ENSO (El Ni$\tilde{n}$o Southern Oscillation) over the Han River Basin. The results show that annual maximum flow has increased statistically significant about 48.3% of all over the watershed. The onset of annual maximum flow was delayed in the west of the Han River basins and in the east of the basins was likely to be rapid onset. Also, this study shows that 7-day low flow was deceased statistically significant about 26.0% of the total area in the Han River Basin, and onset of 7-day low flow tends to be faster in the upper-middle basins of the Han River. The onset of annual maximum flow shows similar pattern during the CT (Cold tongue)/WP (Warm-pool) El Ni$\tilde{n}$o years, but annual maximum flow appeared less in 89.0% of all basins during the CT El Ni$\tilde{n}$o years. In addition, the onset of 7-day low flow tended to be faster about 17 days on average during the WP El Ni$\tilde{n}$o years, and 72.7% of the basins show significant increase during the CT El Ni$\tilde{n}$o years. Consequently, it was found that the different phases of CT/WP El Ni$\tilde{n}$o have effects on sensitivity to variability in quantity and onset of water resources over the Han River Basin. We expect that the present diagnostic study on hydrological variability during different phases of ENSO will provide useful information for long-term prediction and water resources management.

• Journal of Korea Water Resources Association
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• v.41 no.7
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• pp.711-723
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• 2008

In this study, Hydrologic regime alterations(magnitude, magnitude and duration of annual extreme, frequency and duration of high and low pulse, rate and frequency of water condition changes, Range of Variability Approach) were analyzed by using Indicators of Hydrologic Alterations at the 11 major multi-purpose dam. The analysis result of the magnitude of monthly water conditions during drought season, inflow was $6.38m^3/sec{\sim}39.84m^3/sec$ and outflow was $20.36m^3/sec{\sim}49.43m^3/sec$, was increased $1.84%{\sim}200.98%$. The analysis result of the magnitude of monthly water conditions during flood season, inflow was from $79.06m^3/sec{\sim}137.12m^3/sec$ and outflow was from $65.32m^3/sec{\sim}80.16m^3/sec$, was decreased from $18.19%{\sim}40.39%$. The analysis result of the magnitude and duration of annual extreme, 1-day minimum was increased $82.86%{\sim}2,950%$, but 1-day maximum was decreased $34.78%{\sim}83.96%$. The analysis result of the frequency and duration of high and low pulse, low pulse count was decreased $29.67%{\sim}99.07%$ and high pulse count was also decreased $4.6%{\sim}92.35%$ after dam operation. Hydrograph rise rate was decreased $15.84%{\sim}79.31%$ and fall rate was $1.97%{\sim}107.10%$. RVA of 1-day minimum was increased $0.60{\sim}2.67$, also RVA of 1-day maximum was decreased $0.50{\sim}1.00$.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.214-218
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• 2008

하천의 유황특성을 평가 하는 것은 하천생태계의 인위적인 변형을 이해하고 예측하는데 중요한 역할을 한다. 본 연구에서는 댐 건설에 따른 하류하천의 영향을 분석하고자 수문변화 지표모형을 이용하여 용수 전용댐인 영천댐을 대상으로 댐 건설전 후의 유황변동을 분석하였다. 분석결과는 다음과 같다. (1) 월 평균유량은 갈수기와 홍수기 모두 댐건설 후 감소하였다. (2) 연 극치유량의 크기와 기간 분석결과, 댐 건설전 후의 1일 최소유량은 $3.48\;m^3/sec$와 $0.89\;m^3/sec$ 이였으며, 1일 최대유량은 $833.1\;m^3/sec$와 $672.1\;m^3/sec$ 이었다. (3) 연극치 유량의 발생시기 분석결과, 최소유량의 Julian Day는 댐 건설전 180 일(6월), 댐 건설 후 257 일(9월)이었으며, 최대유량의 Julian Day는 댐 건설전 209 일(7월), 댐 건설 후는 217 일(8월)에 발생하였다. (4) 홍수맥파의 빈도와 기간의 분석결과, 저맥파(Low Pulse)의 발생횟수는 댐 건설전 3회, 지속기간은 23 일, 댐 건설 후에는 7회, 지속기간 61 일 이었으며, 고맥파(High Pulse)의 발생횟수는 댐 건설 전 4회 지속기간은 2 일, 댐 건설후에는 2회 1.2 일로 분석되었다. (5) 변화율과 빈도의 분석결과, 상승율은 댐 건설 전, 후의 각각 39.27 %와 19.36 %로 댐 건설 전에 수문변동이 크게 발생하였으며, 감소율은 각각 -15.85 %와 -8.16 %로 분석되었다. (6) 분산정도를 변동계수로 분석하였으며, 1일 최소 최대유량은 0.9054에서 0.6314와 1.0440에서 0.9617로 모두 감소하였으며, 연 극치유량 발생시기는 댐 건설전 후 최소유량은 0.269에서 0.282, 최대유량은 0.069에서 0.153으로 댐건설이후 변동계수가 증가하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.101-101
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• 2021

본 연구에서는 금강 유역(9,645.5 km²)을 대상으로 SWAT(Soil and Water Assessment Tool)을 이용하여 장기간 지하수 양수와 산림 성장이 수문에 미치는 영향을 평가하였다. 1976년부터 2015년까지 40년의 지하수 이용량(GU)과 산림 성장(FG) 자료를 10년 단위(1980s; 1976~1985, 1990s; 1986~1995, 2000s; 1996~2005, 2010s; 2006~2015)로 구축하고, SWAT 입력자료와 증발산량 매개변수로 사용하여 연대별 지하수 양수와 산림 생장을 반영하였다. 금강 유역 내 위치한 2개의 다목적댐과 3개의 다기능 보에서 관측된 일별 유량으로 2006년부터 2015까지 10년을 검·보정하여 모델의 적용성을 검증하였다. 5지점에 대한 검보정 결과, NSE는 0.76에서 0.79, R²는 0.78에서 0.81, RMSE는 0.55 mm/day에서 1.96 mm/day, PBIAS는 -5.48%에서 8.56%로 통계적으로 유의한 수준으로 분석되었다. 적용성을 검증한 SWAT에 각 연대에 맞는 GU와 FG 정보를 입력하여 수문을 모의하였으며, 두 요인이 물순환에 미치는 영향을 평가하기 위하여 기상조건은 2010s로 고정하였다. 모의결과, GU와 FG 변화가 주는 영향으로 유역 출구의 총유출량은 7.8%(60.7 mm/year) 감소하였으며, 1980s과 2010s에서 각각 775.0 mm/year, 714.3 mm/year의 값을 보였다. 물순환 분석 결과, 지표유출, 중간유출, 기저유출, 침투량, 토양수분은 감소하는 경향을 보였고, 증발산량과 지하수 충전량(GWR)은 증가하는 경향을 보였다. GU의 증가로 인한 지하수위의 지속적인 감소가 GWR이 증가하는 원인으로 판단하였으며, 강우 기간에 포장용수량 이상의 토양수가 빠르게 흘러 지하수 충전량을 증가시켰다고 추론하였다. 또한, 유황 곡선을 분석한 결과, 유량이 지하수 양수와 산림 생장에 영향을 받은 지역에서 시간 흐름에 따라 감소하였고, 저유량 구간에서 상대적으로 많이 감소하였다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.6B
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• pp.579-587
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• 2010

The mid-range streamflow forecast was performed using NWP(Numerical Weather Prediction) provided by KMA. The NWP consists of RDAPS for 48-hour forecast and GDAPS for 240-hour forecast. To enhance the accuracy of the NWP, QPM to downscale the original NWP and Quantile Mapping to adjust the systematic biases were applied to the original NWP output. The applicability of the suggested streamflow prediction system which was verified in Geum River basin. In the system, the streamflow simulation was computed through the long-term continuous SSARR model with the rainfall prediction input transform to the format required by SSARR. The RQPM of the 2-day rainfall prediction results for the period of Jan. 1~Jun. 20, 2006, showed reasonable predictability that the total RQPM precipitation amounts to 89.7% of the observed precipitation. The streamflow forecast associated with 2-day RQPM followed the observed hydrograph pattern with high accuracy even though there occurred missing forecast and false alarm in some rainfall events. However, predictability decrease in downstream station, e.g. Gyuam was found because of the difficulties in parameter calibration of rainfall-runoff model for controlled streamflow and reliability deduction of rating curve at gauge station with large cross section area. The 10-day precipitation prediction using GQPM shows significantly underestimation for the peak and total amounts, which affects streamflow prediction clearly. The improvement of GDAPS forecast using post-processing seems to have limitation and there needs efforts of stabilization or reform for the original NWP.

• Journal of Korea Water Resources Association
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• v.41 no.2
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• pp.163-172
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• 2008

Hydrologic regimes play a major role in determining the biotic composition, structure, and function of river ecosystem. In this study, hydrologic regimes were analyzed on down stream effects of the Young-Chun dam construction using the Indicators of Hydrologic Alterations(IHA). The analysis results were as follows ; (1) Monthly mean flows were decreased during drought and flood season on the pre and post dam, (2) Magnitude and Duration of Annual Exterm Conditions, annual minima 1-day means was $3.48m^3/sec$, $0.89m^3/sec$ and annual maxima 1-day mean was $833.1m^3/sec$, $672.1m^3/sec$ on the pre and post dam (3) Timing of Annual Exterm conditions, Julian date of the annual minima 1-day means was 180th(June) in the pre dam, 257th(September) in the post dam, Julian date of the annual maxima 1-day means was 209th(July) in the pre dam, 217th(August) in the post dam, (4) Frequency and Duration of High and Low Pulse, Low Puls counts and duration were 3 times and 23 days in the pre dam, High Pulse counts and duration were 4 times and 2 days in the pre dam. (5) Rate and Frequency of Water Condition Changes, rise rates was 39.27 %, 19.36 % and fall rates -15.85 %, -8.16 % in the pre and post dam, respectively (6) Coefficient of Variation, annual exteram water conditions were decreased from 0.9054 to 0.6314 and from 1.0440 to 0.9617, Timing of Annual Exterm conditions were incereased for minima flow from 0.269 to 0.282, for maxima form 0.069 to 0.153.

• Magazine of the Korean Society of Agricultural Engineers
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• v.32 no.3
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• pp.56-66
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• 1990

To investigate the status of irrigation water use and the degree of repeated use of irrigation water, observations for water balance analysis were made during the irrigation periods in 1986 and 1987 crop year. The total area of studied site is 1,441 ha. The site is a major portion of Jedaecheon basin which is located in Bubuk-myeon, Miryang-gun, Gyeongnam Province. The studied area was subdivided into six small blocks. The water balance analysis for these subdivided blocks were carried out considering characteristics of each block. Obtained results are as follow: 1.In mountainous sloppy paddy area(less than 7% slope), the surface inflow was 5A mm/day in average that is one third of the surface inflow into plain paddy area ; 16.7 mm/day. 2.The surface inflows at the vegetative stage and the ripening stage were 15.5 mm/day and 10.4 mm/day, respectively. Those figures were larger than the actual consumptive use at respective same stages ; 13.3 mm/day and 9.2 mm/day, respectively. Whereas, the surface inflow at generative stage was 12.5 mm/day which was less than 14.0 mm/day ; the actual consumptive use. 3.The range of the variation of water storage term was 1 mm/day. This means that there were no change in depth of ponded water on paddy fields. The relationship between the variation of water storage(AS) and the variation of ground water table(H) could be expressed as follow: : AS=0.14H+0.26 4.The ground water inflow: into the transition region ; paddy fields which are located continuously from the mountainous area to the plain area, was larger than the out flow from this region, in general. Rowever, in the plain region where the ground water utilization was predominant, the ground water outflow from this region was larger than inflow: to this region. The relationship between the ground water flow(G2- G1) and the consumptive use in large paddy area(D1-D2) could be expressed as follow: (G2-G1) =0.95(D1-D2) -3.79

• Journal of Korea Water Resources Association
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• v.53 no.11
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• pp.985-997
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• 2020

SWAT (Soil and Water Assessment Tool)-MODFLOW (Modular Groundwater Flow) is a coupled model that linking semi-distributed watershed hydrology with fully-distributed groundwater behavior. In this study, the groundwater simulation results of SWAT and SWAT-MODFLOW were compared for Bokhacheon watershed in Namhan river basin. The models were calibrated and validated with 9 years (2009~2017) daily streamflow (Q) data of Heungcheon (HC) water level gauge station and the daily groundwater level observation data of Yulheon (YH). For SWAT, the groundwater parameters of GW_DELAY, GWQMN, and ALPHA_BF affecting baseflow and recession phase were treated. The SWAT results showed the coefficient of determination (R²) of 0.7 and Nash-Sutcliffe model efficiencies (NES_Q, NSE_inQ) for Q and 1/Q with 0.73 and -0.1 respectively. For SWAT-MODFLOW, the spatio-temporal aquifer hydraulic conductivity (K, m/day), specific storage (S_s, 1/m), and specific yield (S_y) were applied. The SWAT-MODFLOW showed R², NSE_Q, and NSE_inQ of 0.69, 0.74, and 0.51 respectively. The SWAT-MODFLOW considerably enhanced the low flow simulation with the help of aquifer physical information. The total streamflow of SWAT and SWAT-MODFLOW were 718.6 mm and 854.9 mm occupying baseflow of 342.9 mm and 423.5 mm respectively.

• Tuberculosis and Respiratory Diseases
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• v.47 no.1
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• pp.42-49
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• 1999

Background: In patients with chronic obstructive pulmonary disease(COPD). it is well known that hypoxemia increases the frequency of VPB, which is associated with the poor prognosis such as sudden death. The aim of this study is to evaluate the effect of short and long-term low flow oxygen therapy on the development of VPBs in patients with COPD by correcting the hypoxemia. Method: In 19 patients with COPD, oxygen saturation and VPB's were monitored by pulse oxymeter and 24-hour Holter EKG, with room air and oxygen saturation and VPB's were monitored on the 1st and on the 8th day during oxygen therapy with nasal prong (2L/min). Results : The arterial oxygen saturation was significantly higher on the 1st day of oxygen therapy compared with breathing room air, and was also higher on the 8th day of oxygen therapy than on the 1st day. We found that there was significant correlation between the lowest value of the arterial oxygen saturation and the mean value of the arterial oxygen saturation. The number of VPB's per hour was significantly lower on the 1st day of oxygen therapy compared with breathing room air, and also lower on the 8th day of oxygen therapy than on the 1st day. Our results showed positive correlation between the decrease in the frequency of VPB's and the increase in the lowest arterial oxygen saturation, even though correlation was not significant(p=0.056). Conclusion: With oxygen therapy, the arterial oxygen saturation was increased and the number of VPB's was decreased. Long-term oxygen therapy more than 7days, would be helpful to decrease the number of VPB' s in patients with COPD.