• 한국물환경학회지
• /
• 제24권1호
• /
• pp.44-53
• /
• 2008

To recognize the spatial and temporal variability of water temperature and dissolved oxygen in the Youngsan reservoir formed after dike construction, water temperature and dissolved oxygen data have been observed and analyzed from April, 2002 until March, 2003. As the results, certain stratifications were not distinctly observed in the Youngsan reservoir during summer, which was estimated due to the drainage characteristic from the Youngsan water gates. The yearly variation of water temperature in the Youngsan reservoir is shown seasonally ups and downs by the heat exchange between the atmosphere and the reservoir. On the other hand, dissolved oxygen and water temperature in the Youngsan reservoir have been shown inversed proportional correlation. As the calculation results of residence time and water exchange rate, it is considered that the feature of oxygen distribution is determined by the drainage characteristics caused the shortest residence time during summer, which also disturbed the formation of stratification in the Youngsan reservoir.

• 스마트미디어저널
• /
• 제13권2호
• /
• pp.16-22
• /
• 2024

Greenhouse provides opportunities to have big yield effectively and efficiently. However, many resources are required, such as fertigation, a kind of solution of nutrient. Resources supply is essential to cultivate crops. Inadequate supply will hinder plant growth whereas the surplus results in waste. In this paper, we are especially interested in the fertigation supply. Further, excess fertigation leads to drainage which is difficult to purify and threatens the environment. To address this challenge, we aim to predict the desired amount of fertigation. To achieve this objective, we first establish a prototype to record the climate conditions inside a rose greenhouse using Internet of Things sensors. Simultaneously, the desired fertigation amount is obtained with the help of weight scale and historical data of fertigation supply and drainage. Second, a method is proposed to predict the desired fertigation by taking the sensors' data as input, with a time-series model. Extensive experimental results suggest the potential of our objective and method. To be specific, our method achieves an average MAE 0.032 in the validation datasets.

• 한국농공학회지
• /
• 제34권4호
• /
• pp.59-68
• /
• 1992

A Study was made to improve soil and water temperature and mechanized farming for a wetted paddy under the influence of artesian groundwater located at Samcheon-Dong, Chuncheon City, Kangweon Province. Half perforated PVC drainage pipes were installed in the test paddy to observe temperature change of water and soil. The temperature of the water in the paddy and soil itself raised significantly after the installation of the half perforated PVC pipes. A subsequent improvement of growth and yield of rice on the paddy was achieved. Harvesting operation was also improved with firm ground condition so that cutting and threshing could be done simultaneously within the paddy plot. Following results were obtained from the study. 1.Temperature of the water in a paddy under the influence of artesian groundwater was not changed notably although air temperature was fluctuated during the crop period. Soil temperature was mostly affected by the artesian groundwater. However, the half perforated PVC pipe drainage system made it possible to raise temperature of water and soil remarkably up to the level of optimum farming. 2.Total precipitation was 534.Omm during the crop period of the paddy for 118 days from May 26 to September 20 in 1992. Due to heavy rainfalls of 105.6mm and 109.8mm occurred on August 7 and August 27.1992, respectively, the rate of the artesian groundwater increased to 35 litter per minute with two to three days of time lag. 3.Average rate of the artesian groundwater was 28 litter per minute from the one year of observation. The rate varied by 0.7 to 1.3 times of average during the observation period. Peak rate of the artesian groundwater decreased to 14.5 litter per minute when daily precipitation maintained at the amount of 20 to 30mm for a long time period. Contrarily, it showed a tendency to increase to 35 to 40 litter per minute when heavier precipitation of 50 to l00mm occurred in a short period of three to five days. 4.Growth and yield of Yemyung variety of rice planted on the paddy that was facilitated with a drainage system with half perforated PVC pipes were confirmed at a normal level, while paddy without this perporated drainage system showed abnormal growth with low yield.

• 한국수소및신에너지학회논문집
• /
• 제25권5호
• /
• pp.516-524
• /
• 2014

Proper discharge of nitrogen gas and water condensate is required in a conventional fuel cell system for performance, stability and durability of fuel cell stacks. Present study covers the development of integrated unit and its functioning logic for simultaneous nitrogen gas purge and water condensate drainage in a fuel cell vehicle system. Configuration of condensate drainage pipe, purge valve and level sensor is considered and optimized in physical integration. As a key factor, discharge time is considered and optimized based on the test result of constant-current operation with various operating temperature in logic development. Consequently, derived optimal values are applied and verified in actual vehicle drive mode test. Increase of system design flexibility, weight reduction and cost reduction are anticipated with this study. Additional study for physical and logical improvement is currently being implemented.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2000년도 봄 학술발표회 논문집
• /
• pp.685-692
• /
• 2000

Vertical drain used improvement soft clay is made of not only decreasing construction time but also increasing the ground strength during some decades. As, it is applied to improvement soft clay with vertical drain, it is designed by the result that is caused by oedemeter test ignored anisotropic of the ground related to consolidation conditions. When we are expected consolidation conditions, the most important factors is soil of compaction and water permeability. Above all, anisotropic of the ground permeability show the results which differ between vertical and radial drainage. Recently, We study for radial consolidation coefficient and permeability coefficient that utilized Rowe Cell Consolidation and permeability tester but, it dont use well because of not only a supply lack also difficulty of test. The paper experimented with searching anisotropic of the ground so there are Rowe Cell test, standard consolidation tester and modified standard consolidation test that have pohang's soft clay ground. Therefore, we find anisotropic of the ground and a tester of easy use more than before. We made a comparison test result between the devised tester and Rowe Cell tester, Also, we learned average degree of consolidation for partial penetrating vertical drains. We were found relations as effective stress-void and effective stress-permeability coefficient through those tests.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2010년도 추계 학술발표회
• /
• pp.969-978
• /
• 2010

In this study, a laboratory model test on utilization of recycled aggregates and crushed stone as vertical drains to use alternative material of sand in soft ground is performed. The vertical and horizontal coefficient of permeability of the recycled aggregates and crushed stone showed largely 1.2~4.0 times and 3.0~3.3 times greater than sand, respectively. Therefore, it showed enough to be an alternative material to the sand which had been being used as the vertical and horizontal drainage material before. The variations of pore water pressure with time showed constantly regardless of the load in all vertical drainage materials. When water level drops suddenly, the pore water pressure of the recycled aggregate and crushed aggregate is reduced to nearly zero. Therefore, it was applicable to the field because discharge capacity was similarity to that of sand. The settlement in crushed aggregates and recycled aggregate decreases gradually with the load increase. When water level drops suddenly, earth pressure in all drains materials was evaluated the equivalent drainage capacity similarity to sand because it show approaching the nearly zero.

• Geomechanics and Engineering
• /
• 제13권2호
• /
• pp.285-300
• /
• 2017

Shallow coal resources are increasingly depleted, the mining has entered the deep stage. Due to "High stress, high gas, strong adsorption and low permeability" of coal seam, the gas drainage has become more difficult and the probability of coal and gas outburst accident increases. Based on the flow solid coupling theory of coal seam gas, the coupling model about stress and gas seepage of coal seam was set up by solid module and Darcy module in Comsol Multiphysics. The gas extraction effects were researched after applying hydraulic technology to increase permeability. The results showed that the effective influence radius increases with the expanded borehole radius and drainage time, decreases with initial gas pressure. The relationship between the effective influence radius and various factors presents in the form: $y=a+{\frac{b}{\left(1+{(\frac{x}{x_0})^p}\right)}}$. The effective influence radius with multiple boreholes is obviously larger than that of the single hole. According to the actual coal seam and gas geological conditions, appropriate layout way was selected to achieve the best effect. The field application results are consistent with the simulation results. It is found that the horizontal stress plays a very important role in coal seam drainage effect. The stress distribution change around the drilling hole will lead to the changes in porosity of coal seam, further resulting in permeability evolution and finally gas pressure distribution varies.

• 농업과학연구
• /
• 제37권1호
• /
• pp.97-104
• /
• 2010

In this study, a laboratory model test on utilization of recycled aggregates and crushed stone as vertical drains to use alternative material of sand in soft ground is performed. The vertical and horizontal coefficient of permeability of the recycled aggregates and crushed stone showed largely 1.2~4.0 times and 3.0~3.3 times greater than sand, respectively. Therefore, it showed enough to be an alternative material to the sand which had been being used as the vertical and horizontal drainage material before. The variations of pore water pressure with time showed constantly regardless of the load in all vertical drainage materials. When water level drops suddenly, the pore water pressure of the recycled aggregate and crushed aggregate is reduced to nearly zero. Therefore, it was applicable to the field because discharge capacity was similarity to that of sand. The settlement in crushed aggregates and recycled aggregate decreases gradually with the load increase. When water level drops suddenly, earth pressure in all drains materials was evaluated the equivalent drainage capacity similarity to sand because it show approaching the nearly zero.

• 한국지반공학회논문집
• /
• 제19권1호
• /
• pp.131-142
• /
• 2003

본 논문은 점성토 지반에 동전기 공법을 적용할 때 지반내에서 발생하는 현상과 그 특성을 고려하여 전기삼투 현상을 예측하고자 하였다. 이를 위하여 납으로 오염된 카올린에 대해 실내실험을 수행하여, 동전기 처리 동안 변화하는 시료의 전압, 전류, 제타포텐셜, pH분포 등의 물리 화학적 현상 간 상관성을 고려한 전기삼투 유한차분 수치 해석 프로그램을 개발하여 실험 결과와 비교하고 각 현상을 검토하였다. 그 결과, 전기삼투 흐름은 점토의 화학적 특성과 전기적 특성 변화에 매우 민감하였다. 간극수의 이온 농도가 증가하면 흐름속도는 감소하였으며, 시간에 따라 배수량은 감소하였다.

• Advances in pediatric surgery
• /
• 제17권1호
• /
• pp.51-57
• /
• 2011

Use of laparoscopic appendectomy (LA) for perforated appendicitis (PA) in children remains controversial because of the development of postoperative intra-abdominal abscess formation. We developed the irrigation method for the prevention of abscess formation after LA performed for PA in children with severe panperitonitis. We called it 'the shaking irrigation'. The object of this study was to analyze the efficacy of this irrigation method. All cases of PA with severe panperitonitis in children that underwent LA with massive shaking irrigation and drainage between June 2003 and December 2007 were studied retrospectively. We included only PA with panperitonitis and large amounts of purulent ascites throughout the abdomen as well as an inflamed small bowel with ileus. Thirty-four children were involved in this study. The mean patient age was eight years. The mean amount of irrigation fluid was 8.2 L (range: 4-15 L), The mean operative time was 89.5 min. The mean length of the hospital stay was 5.1 days. There were no postoperative intra-abdominal abscesses. There was no conversion to open surgery. In conclusion, Use of LA in PA with severe panperitonitis in children is safe and effective. Massive shaking irrigation and abdominal drainage appears to prevent intra-abdominal abscesses after LA for PA with panperitonitis.