• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2017년도 학술발표회
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• pp.166-166
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• 2017

현재 우리나라에서 많은 연구에 활용되고 있는 오염부하지속곡선(Load duration curve, LDC)은 단일 기준유량의 문제점을 개선하기 위해 전체 유량 범위를 고려한 수질오염총량관리제(Total Maximum Daily Loads, TMDL) 평가 기법으로 개발되었다(Choi et al., 2012). LDC를 이용해 목표수질 달성여부를 분석하기 위해서는 일유량자료를 바탕으로 유량지속곡선(Flow Duration Curve, FDC)의 작성이 선행되어야 하는데(Park and Oh, 2012), 365일 연속적으로 측정된 실측 자료를 이용하는 것이 가장 확실하고 정확한 방법이다. 그러나 현재 환경부에서는 총량관리 단위유역에서 8일 간격으로 실측 유량 및 수질 측정이 이루어지고 있고, 특히 주로 비강우 시에 측정이 이루어지고 있는 실정이기 때문에 고유량에 대한 모니터링 자료가 부족한 실정이다. 이 같은 이유로 많은 연구에서 불연속적인 평균 8일 간격 유량을 그대로 사용하거나 일유량자료를 확보하기 위해 다양한 방법을 이용하고 있다. 그러나 이러한 유량자료의 변동은 유랑지속곡선에 변화를 주고 결과적으로는 LDC를 이용한 목표수질 달성여부를 판단함에 있어 불확실성이 있다. 이에 본 연구의 목적은 환경부 총량측정망 8일유량자료와 이와 연계성이 있는 국토교통부 하천유량 측정망 일유량자료를 이용하여 각각의 LDC를 작성하고, 이러한 일유량과 8일유량 사용이 LDC를 이용하여 목표수질에 대한 오염부하 특성분석에 어떠한 영향을 미치는지 유량 조건별로 차이를 비교분석하는 데 있다.

• 한국농공학회논문집
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• 제57권1호
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• pp.69-78
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• 2015

The objective of this study was to investigate characteristics of irrigation return flow from paddy block in a reservoir irrigated district during growing seasons. The irrigation return flow was divided into three parts, quick return flow from irrigation canal (RFI), quick return flow from drainage canal (RFD), and delayed return flow (DRF). The RFI was calculated from water level and stage-discharge relationships at the ends of the irrigation canals. The DRF was estimated using measured infiltration amount from paddy fields of the irrigated district. A combined monitoring and modeling method was used to estimate the RFD by subtracting surface runoff from surface drainage. The paddy block irrigated from the Idong reservoir was selected to study the irrigation return flow components. The results showed that daily agricultural water supply (AWS), the RFI, and the RFD were $27.4mm\;day^{-1}$, $4.9mm\;day^{-1}$, and $19.8mm\;day^{-1}$, respectively in May, which were greater than other months (p<0.05). The return flow ratio of the RFI and the RFD were the greatest in July (34.6%) and May (72.3%), respectively. The daily AWS was closely correlated with the RFD (correlation coefficients of 0.76~0.86) in except for July with, while correlation coefficient with the RFI were 0.56 and 0.42 in June and July, respectively (p<0.01). The total irrigation return flow was 1,965 mm in 2011, and 1,588 mm in 2012, resulting in total return flow ratio of 84.6% and 79.1%, respectively. This results indicate that substantial amounts of agricultural water were returned to streams as irrigation return flow. Thus, irrigation return flow should be fully considered into the agricultural water resources planning in Korea.

• 한국환경보건학회:학술대회논문집
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• 한국환경보건학회 2004년도 International Conference Global Environmental Problems and their Health Consequences
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• pp.193-196
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• 2004

To evaluate the acute effects of fine particles on pulmonary function, a longitudinal study was conducted. This study was carried out for the schoolchildren (3rd and 6th grades) living in Beijing, China. Children were asked to record their daily levels of peak expiratory flow rate using portable peak flow meter (mini-Wright) for 40 days. The relationship between daily PEFR and fine particle levels was analyzed using a mixed linear regression models including gender, height, the presence of respiratory symptoms, and daily average temperature and relative humidity as extraneous variables. The total number of students participating in this longitudinal study was 87. Daily measured PEFR was in the range of $253{\sim}501L/min$. On the daily basis, a PEFR measured in the morning was shown to be lower than that measured in the evening (or afternoon). The daily mean concentrations of $PM_{10}$ and $PM_{2.5}$ over the study period were $180.2\;{\mu}g/m^3$ and $103.2\;{\mu}g/m^3$, respectively. The IQR (inter-quartile range) of $PM_{10}$ and $PM_{2.5}$ were $91.8\;{\mu}g/m^3$ and $58.0\;{\mu}g/m^3$. Daily mean PEFR was regressed with the 24-hour average $PM_{10}$ (or $PM_{2.5}$) levels, weather information such as air temperature and relative humidity, and individual characteristics including gender, height, and respiratory symptoms. The analysis showed that the increase of fine particle concentrations was negatively associated with the variability in PEFR. The IQR increments of $PM_{10}$ or $PM_{2.5}$ (at 1-day time lag) were also shown to be related with 1.54L/min (95% Confidence intervals -2.14, -0.94) and 1.56L/min (95% CI -2.16, -0.95) decline in PEFR.

• 한국치위생학회지
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• 제18권6호
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• pp.903-910
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• 2018

Objectives: The study aimed to identify the oral health factors that affect the nutritional status of the elderly. Methods: The study was conducted over ten months from September 2013 to June 2014, and included senior citizens who were supported by the visiting health service. The rate of saliva release, the number of remaining teeth, and the ability of the elderly to identify nutritional conditions were evaluated. Statistical analyses were performed using the t-test, ANOVA, and multiple linear regression using SAS 9.4 (SAS Institute Inc., Cary, NC, USA.). Results: The study participants had an average irritation saliva secretion rate of $2.26{\pm}1.11mg$ per minute. The higher the rate of saliva secretion, the higher the mini nutritional assessment (MNA) score (p<0.001). The average number of remaining teeth was $8.21{\pm}9.76$. The MNA scores were highest in groups with 11 or more remaining teeth (p=0.001). The factors that affected the nutritional condition of the elderly were their ability to perform activities of daily living, saliva flow rate, and number of remaining teeth. The highest correlation among them was that of the standardized regression coefficient was - 0.386 by activity daily living, followed by a 0.170 saliva secretion rate and 0.118 remaining teeth in daily life performance. Conclusions: Activities of daily living and rate of saliva secretion showed the highest correlations to nutritional status of the elderly.

• 한국수자원학회논문집
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• 제54권10호
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• pp.795-805
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• 2021

본 연구는 소양강댐 유역을 대상으로 LSTM 기반의 일유출량 추정 딥러닝 모형을 개발한 후, 모형구조 및 입력자료의 다양한 조합에 대한 모형의 정확도를 살폈다. 첫 12년(1997.1.1-2008.12.31) 동안의 유역평균 일강수량, 일기온, 일풍속 (이상 입력), 일평균 유량 (출력)으로 이루어진 데이터베이스를 기반으로 모형을 구축하였으며, 이후 12년(2009.1.1-2020.12.31) 동안의 자료를 사용하여 Nash-Sutcliffe Model Efficiency Coefficient (NSE)와 RMSE를 살폈다. 가장 높은 정확도를 보인 조합은 64개의 은닉유닛을 가진 LSTM 모형 구조에 가능한 모든 입력자료(12년치의 일강수량, 일기온, 일풍속)를 활용한 경우로서 검증기간의 NSE와 RMSE는 각각 0.862와 76.8 m³/s를 기록하였다. LSTM의 은닉유닛이500개를 초과하는 경우 과적합으로 인한 모형의 성능 저하가 나타나기 시작했으며, 1000개를 초과하는 경우 과적합 문제가 두드러졌다. 12년치의 일강수만 입력자료로 활용한 경우에도 매우 높은 성능(NSE=0.8~0.84)의 모형이 구축되었으며, 한 해의 자료만을 활용하여 학습한 경우에도 충분히 활용 가능한 정확도(NSE=0.63~0.85)를 가진 모형을 구축할 수 있었다. 특히 유량의 변동성이 큰 한 해의 자료만을 활용하여 모형을 학습한 경우 매우 높은 정확도(NSE=0.85)의 모형이 구축되었다. 학습자료가 중유량과 양극한의 유량을 모두 포함한 경우라면 5년 이상의 입력자료는 모형의 성능을 크게 개선시키지 못했다.

• 농업과학연구
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• 제38권1호
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• pp.163-172
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• 2011

To provide the operation rule curve for suppling instream flow to urban stream from reservoir, the Soho reservoir with watershed area of 7.4 $km^2$ and total water storage of 2.58 $Mm^3$ was planned at the headwaters of the Daejeoncheon. Daily streamflow was simulated and using the simulated streamflow and desired instream flow, the operation rule curve by Senga method was drawn and evaluated through reservoir operation. Senga method is derived by accumulating the differences between streamflow and desired instream flow adversely. Water storages were simulated on a daily basis to supply urban instream flow from Soho reservoir, but the amount of supplying instream flow to urban stream was not nearly increased comparing with that of normal operation that does not used the rule curve. Thereafter the new simulation-based operation rule curve was derived and applied to supply instream flow from Soho reservoir. In normal operation, the amount of instream flow was shown to 15,000 $m^3$/d, but it was increased to 27,700 $m^3$/d in withdrawal limited operation using the new derived rule curve, in which the applicability of this rule curve was proved. Also comparing with the flow duration curves at station just before urban Daejeoncheon stream without and with upstream Soho reservoir, the 95th flow was decreased from 1.64 mm/d to 1.51 mm/d, and the 355th flow was increased from 0.17 mm/d to 0.30 mm/d. Monthly streamflows during October to March were increased from 10.6~24.1 mm to 24.1~34.0 mm with the increasing rate of 141~227%.

• 한국물환경학회지
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• 제28권6호
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• pp.890-895
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• 2012

Duration curves describe the percentage of time that a certain water quality (total/fecal coliform (=TC/FC)) or discharge is exceeded. The curves methodology are usually based on daily records and are useful in estimating how many days per year and event will be exceeded. The technique was further applied to estimated TC/FC loading to the Geumho River, using the daily mean flow rate and TC/FC concentration data during January, 2001 and December, 2011 for the Geumhogang6 (=Seongseo water level station) where an automated monitoring station is located in Gangchang-bridge. Low flow of the Seongseo (=11.1 cms) was equivalent to 75.3% on an exceedance probability scale. Load Duration curve for TC/FC loading at the Seongseo was constructed. Standard load duration curve was constructed with the water quality criteria for class III (TC/FC concentration = 5000/1000 CFU/ 100 mL). By plotting TC/FC observed load duration curve with standard load duration curve, it could be revealed that water quality do not meet the desired water quality for 68.8/11.2% on an exceedance probability scale. IF linear correlation between flow rate and coliform concentration is assumed, it can be interpreted that water quality exceed desired criteria when daily average flow rate is over 11.9/109.9 cms.

• 한국환경보건학회지
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• 제30권2호
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• pp.140-148
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• 2004

To evaluate the acute effects of fine particles on pulmonary function, a longitudinal study was conducted. This study was carried out for the schoolchildren (3rd and 6th grades) living in Beijing, China. Each child was provided with a mini-Wright peak flow meter and a preformatted health symptom diary for 40 days, and was trained on their proper use. Participants were instructed to perform the peak flow test three times in standing position, three times a day (9 am, 12 pm, and 8 pm), and to record all the readings along with the symptoms (cold, cough, and asthmatic symptoms) experienced on that day. Daily measurement of fine particles (PM$_{10}$ and PM$_{2.5}$) was obtained in the comer of the playground of the participating elementary school for the same period of this longitudinal study. The relationship between daily peak expiratory flow rate (PEFR) and fine particle levels was analyzed using a mixed linear regression models including gender, height, the presence of respiratory symptoms, and daily average temperature and relative humidity as extraneous variables. The total number of students participating in this longitudinal study was 87. The range of daily measured PEFR was 253-501$\ell$/min. In general, the PEFR measured in the morning was lower than the PEFR measured in the evening (or afternoon) on the same day. The daily mean concentrations of PM$_{10}$ and PM$_{2.5}$ over the study period were 180.2$\mu\textrm{g}$/㎥ and 103.2$\mu\textrm{g}$/㎥, respectively. The IQR (inter-quartile range) of PM$_{10}$ and PM$_{2.5}$ were 91.8$\mu\textrm{g}$/㎥ and 58.0$\mu\textrm{g}$/㎥. During the study period, the national ambient air quality standard of 150$\mu\textrm{g}$/㎥ (for PM$_{10}$) was exceeded in 23 days (57.5%). The analysis showed that an increase of 1$\mu\textrm{g}$/㎥ of PM$_{10}$ corresponded to 0.59$\mu\textrm{g}$/㎥ increment of PM$_{2.5}$. Daily mean PEFR was regressed with the 24-hour average PM$_{10}$ (or PM$_{2.5}$) levels, weather information such as air temperature and relative humidity, and individual characteristics including gender, height, and respiratory symptoms. The analysis showed that the increase of fine particle concentrations was negatively associated with the variability in PEFR. The IQR increments of PM$_{10}$ or PM$_{2.5}$ (at 1-day time lag) were also shown to be related with 1.54 $\ell$/min (95% Confidence intervals: 0.94-2.14) and 1.56$\ell$/min (95% CI: 0.95-2.16) decline in PEFR.R.ine in PEFR.ine in PEFR.

• 한국물환경학회지
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• 제35권6호
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• pp.481-496
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• 2019

The Ministry of Environment has measured streamflow at eight-day intervals for the estimation of standard flow of the Total Maximum Daily Loads (TMDL) system. This study identified the availability of the partially measured the eight-day interval data for estimating standard flow and found the optimal extension techniques of standard flow. The study area was selected for the Nakbon-A watershed in the Nakdong River, and four streamflow record extension techniques of standard flow were considered: extension, percentile, drainagearea, and regional regression methods. The flow duration curve (FDC) using the eight-day interval streamflow data indicated very high Nash and Sutcliffe Efficiency (NSE) values above 90 % from FDC-II to FDC-VII compared to FDC-VIII, the standard FDC. This result demonstrates that FDC using daily data of three-six cumulative years could represent standard FDC fairly well. For the streamflow record extension techniques of standard flow, the percentile method was selected as the optimal alternative, showing the minimal difference from FDC-VIII. These results validate the availability of the eight-day interval streamflow data in the standard flow estimation and the application of extension techniques. It seems that these results could reduce the uncertainty of partially measured streamflow data for water quantity and quality management.

• 한국농공학회지
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• 제30권2호
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• pp.95-104
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• 1988

This study refers to the development of a hydrologic model simulating daily inflow and release rates for inigation reservoirs. A daily - based model is needed for adequate operation of an irrigation reservoir sufficing the water demand for paddy fields which is closely related to meteorological conditions. And the objective of this study is to develop a reservoir release rate model and then to calibrata the parameters. The release rates model considers daily water demands , water supply for transplanting, minmum release for maintaining canal flow, and maxirnun and regular flooding depth for determining effective rainfall on paddy fields. Each of the factors in the model was regarded as a lumped pararuter representing the average condition of a whole irrigated area. The water demand was estimated form the potential evapotranspiration by Penman method, the effective rainfall, and the infiltration on paddy fields. The release model was found to be capable of adequately simulating daily reservoir releases based on meteorological data.