• 한국농공학회논문집
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• 제48권2호
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• pp.45-55
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• 2006

This study analyze the hydrologic conditions and the effects of selected runoff characteristics as an attempt to estimate the optimal dredge amount for Asan Lake in Korea. The runoff feature was calculated by utilizing the water balance simulation from DIROM (Daily Irrigation Reservoir Operation Model), which allowed changes in landuse to be quantified using remote sensing for 14 years. The distribution of prospective sediment deposits was been tallied based on the changes in landuse, and quantity of incoming sediment estimated. From these findings, we were then able to simulate the fluctuation of water level, gauging the pumping days not already in use, to determine the frequency of the distribution for around the. requirement annual water storage and the changing water level. The optimal dredge amount was calculated on the basis of the distribution of frequency, taking into account the design criteria for agricultural water with the 10-year frequency of resistant capacity.

• 한국농공학회지
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• 제17권4호
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• pp.4001-4008
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• 1975

The economic evaluation of the feasibility of expanding fully irrgated agriculture in the Ogseo project must consider preproject yields of rice under rainfed and partially irrigated paddy cultivation in order to assess incremental incomes from irrigation. Statistical data on yields available from official sources and field surveys conducted in the project area do not specify whether given unit yields refer to actually cropped or potentially cropped lands. This latter factor obviously affects any evaluation of marginal benefits to be derived from irrigation as the extent of rainfed areas actually cropped varies from year to year according to rain fall at the critical growth periods for low land rice. Although less dependent on direct rainfall, yields from partially irrigated lands are also highly affected by seasonal rainfalls. In this paper on attempt has been made to determine average yield under rainfed and partially irrigated conditions by relating yields to a available water. For rainfed paddy cultivation, the analysis discriminates between effects of rain deficiencies during transplanting and subsquent growth periods. For partially irrigated paddy cultivation, seasonal rainfalls have been considered, implying sufficient storage capacity for supplementary irrigation. The average yield of rainfed paddy has been calculated as 2.11 t/ha and that of partially irrigated paddy as 2.8 t/ha. Assuming even division between these two water supply patterns of areas not fully irrigated, a composite yield of 2.46 t/ha is oftained. This figure will be adopted as the basis for the on-going studies and project evaluation.

• 기술사
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• 제1권1호
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• pp.18-25
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• 1968

Higher yield in rice paddies is greatly dependent on adequately balanced and timely supply of water. A majority of rice paddy in Korea is generally irrigated by rainfall, but in many cases it has to be supplemented by artificial irrigation for optimum rice culture. Although the water requirement of rice plant is for higher Than that of athec crops, submerged condition of rice paddy is not Necessarily required. The moisture requirement of rice plant varies with its growing stages, and it is possible to increase the irrigation efficiency through reduction of water loss due to percolation in rice paddies. An experimental plots were set up by means of sandomized block design with three duplication; (a) All time submerged, (b) Economically controlled, and (c) Extremely controlled. Three different irrigation periods Were (a) Initial sage, (b) Inter-stage, and (c) Yast stage. The topsoil of the three plots were excavated to the depth of 30 cm and then compacted with clay of 6 cm thickness. There after, they were piled up with the excavated top soils, leveled and cored with clay of 6 cm thickness around footpath in order to prevent leakage. The results obtained from the experiments are as follows, 1. There is no difference among the three experiments plots in terms of physical and chemical conditions, soil properties, and other characteristics. 2. Culm length and ear length are not affected by different irrigation methods. 3. There is no difference in the mature rate and 1, 000 grain weight of rice for the three plots. 4. The control plot which was irrigated every three days shows an increased yield over the all the time submerged plot by 17.8 percent. 5. The clay lined plot whose water holding capacity was held 5 days long, needs only to be irrigated every 7 days. 6. The clay lined plot shows an increased yield over the untreated plot ; over all-the-time submerged plot by 18 percent ; extremely controlled plot by 18 percent, and economically controlled plot by 33 percent. 7. It may be saved in water requirement about one Thirds.

• 한국농공학회논문집
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• 제63권3호
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• pp.1-12
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• 2021

Optimal water management is to efficiently and equally supply an appropriate amount of water by using irrigation facilities. Therefore, it is necessary to evaluate water supply capacity through distribution simulation between the designed distribution rate and re-distributed rate according to the changed farming conditions. In this study, we recalculated the agricultural water supply amount of Geumcheon main canal, which beneficiary area was reduced due to the development of Gwangju-Jeonnam innovation city, and we constructed a canal network using the SWMM model to simulate the change in supply rate of each main canal according to the re-distributed rate. Even though the supply amount of the Geumcheon main canal was reduced from 1.20 m³/s to 0.90 m³/s, it showed a similar supply rate to the current, and the reduced quantity could be supplied to the rest of the main canal. As a result, the arrival time at the ends of all main canal, except for the Geumcheon main canal, decreased from 1 to 3 hours, and the supply rate increased from 4 to 17.0% at the main canal located at the end of the beneficiary area of Naju reservoir.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2022년도 학술발표회
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• pp.516-516
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• 2022

Agricultural reservoirs are critical water resources structures to ensure continuous water supplies for rice cultivation in Korea. Climate change has increased the risk of reservoir failure by exacerbating discrepancies in upstream runoff generation, downstream irrigation water demands, and evaporation losses. In this study, the variations in water balance components of 400 major reservoirs during 1973-2017 were examined to identify the reservoirs with reliable storage capacities and resilience. A conceptual lumped hydrological model was used to transform the incident rainfall into the inflows entering the reservoirs and the paddy water balance model was used to estimate the irrigation water demand. Historical climate data analysis showed a sharp warming gradient during the last 45 years that was particularly evident in the central and southern regions of the country, which were also the main agricultural areas with high reservoir density. We noted a country-wide progressive increase in average annual cumulative rainfall, but the forcing mechanism of the rainfall increment and its spatial-temporal trends were not fully understood. Climate warming resulted in a significant increase in irrigation water demand, while heavy rains increased runoff generation in the reservoir watersheds. Most reservoirs had reliable storage capacities to meet the demands of a 10-year return frequency drought but the resilience of reservoirs gradually declined over time. This suggests that the recovery time of reservoirs from the failure state had increased which also signifies that the duration of the dry season has been prolonged while the wet season has become shorter and/or more intense. The watershed-irrigated area ratio (W-I_ratio) was critical and the results showed that a slight disruption in reservoir water balance under the influence of future climate change would seriously compromise the performance of reservoirs with W-I_ratio< 5.

• 물과 미래
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• 제10권1호
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• pp.20-24
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• 1977

43,000 shallow water wells have been installed as a part of all weather irrigation water supply project executed during 1969 to 1970 in all over Korea penninsula in order to solve water shortage problem of farming land by developing shallow ground water reserved in unconsolidated materials. But after 3 years later it was reported that 34% of the wells were abandoned by the reasons of artificial and natural defects. 48 wells distributed uniformly in the penninsula are selected to determine their well loss constants, relation between well loss and specific capacity, and tophographic classification of the well loss on the shallow water well. The results show that average well loss consatnt and the value of $CQ^2/S_w$ is ranged from $5.95{\times}10^{-5}\;to\;3.65{\times}10^{-8}Day^2M^{-5}$ and from 35.5% to maximum 68.48% respectvely and that relation between specific capacity and well loss constant can be approximately formulated as $C=0.61S_p2.246$ However this result indicates that most wells installed in this time have too high value of well loss constant $CQ^2/S_w$ in comparison with properly deseigned well. The most favorable and producable water bearing formation among unconsolidated deposits such as sand & gravel, boulderly gravel, clayey boulderly gravel, and sand formation in Korea is sand formation deposited in center of valley.

• 생물환경조절학회지
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• 제6권3호
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• pp.159-167
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• 1997

플러그육묘의 대량생산 보급에 대처하기 위하여는 정식기의 보급이 필요하다. 본 연구에 서는 국내보급중인 반자동정식기의 정식성능을 조사 분석하므로써 기계정식 작업시 최적작업조건 구명과 정식기 연구 개발의 기초 자료를 획득하고자 실시하였고, 정식시험을 실시한 결과를 요약하면 다음과 같다. 1. 호퍼의 크기는 정식자세와 정식율에 영향을 미치고, 진압이 불량한 정식육묘는 1일후 고사하므로 재관수가 필요하였다. 따라서 복토진압장치는 전후좌우 진압법이 좋으며, 2중관수장치에 의하여 정식시의 관수량을 늘려야할 것으로 생각되나 물통의 용량이 또한 커지게 되어 기계의 운전 조작이 어렵게 되므로 자동육묘공급 정식기는 공간문제와 1~2인 작업을 전제로 할 때 효율면에서 자동관수는 없는 것이 바람직할 것으로 사료된다. 2. 반자동정식기는 몇 가지의 구조적 개선이 필요하지만 현재로도 정식기계의 운전을 주행 속도 14m/min 이하, 정식깊이 2~3cm, 간격 30cm로 하고 고추 육묘는 128공의 45일 육묘, 배추는 128공의 25육묘를 사용하면 플러그육묘의 정식에 적합한 것으로 생각된다.

• 한국농공학회논문집
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• 제61권6호
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• pp.93-101
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• 2019

This study aims to analyze the influences of applications of two different evapotranspiration (ET) estimation methods on the irrigation water requirements (IWR) for paddy rice and water supply reliability of agricultural reservoirs. The modified Penman (MP), traditional method, and the Penman-Monteith (PM), the new adopted method, were applied on 149 reservoirs located in Honam province for this study. The weather date was used from 1987 to 2016, and analysed the trends of temperature and rainfall during rice growing season between past and current 10 years respectively. The increased average temperature and rainfall were observed from the current 10 years compared to the past years. This phenomena impacts on the results of ET and IWR estimations with decreased IWR obtained from high rainfall regions and increased ET obtained high temperature regions. For the comparisons of application results of two ET approaches, the PM method showed lower ET and IWR, and hence more reliable storage capacity of the reservoirs respect to water supply to paddy fields. The results also showed that the influences of different ET methods applications on the water supply reliability of reservoirs are negligible for the cases of over 3.7 watershed ratio and 670 mm unit reservoir storage, while significant variations of the results obtain from the applications between two ET approaches for the opposite cases. Further studies are necessary to consider various field conditions for practical applications of the PM method estimating ET in the fields of paddy farming.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2005년도 학술발표논문집
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• pp.260-265
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• 2005

The purpose of this study is to established a storage management method and operation standard for irrigation dams occupying the largest portion of small dams using storage management system. The system can be applied to seongju dam for effective management. The storage management method was established considering hydrology simulation and statistical analysis using the system. This method and operation standard are capable of analyzing additional available water, considering the water demand and supply of basin actually. It can improve the flood control capacity and water utilization efficiency by the flexible operation of storage space.

• 한국농공학회논문집
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• 제65권5호
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• pp.13-24
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• 2023

Due to recent climate change, the amount of rainfall during the summer season in South Korea has been decreasing, leading to an increase in areas affected by frequent droughts. Droughts have the characteristic of occurring over a wide area and being unpredictable in terms of their onset and end, necessitating proactive research to cope with them. In this study, we conducted an assessment of agricultural drought vulnerability in Taean-gun, Chungcheongnam-do, focusing on irrigation facilities and paddy fields. The assessment criteria were meteorological impact, drought occurrence status, supplementary water supply capacity, and drought response capability, with nine specific indicators selected. The drought response capability was analyzed by applying a scoring system as a key component of the agricultural drought vulnerability assessment, while the other indicators were quantified using an entropy weighting technique. The results of the assessment showed that Anmyeon-eup and Taean-eup were the safest areas, while Wonbuk-myeon, Nam-myeon, and Gonam-myeon were the most vulnerable. It is expected that the findings can be utilized to enhance understanding and proactive measures for coping with agricultural drought, and to determine the priority of drought response in different regions.