• Journal of Mechanical Science and Technology
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• v.19 no.8
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• pp.1582-1596
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• 2005

Groundwater flow and behavior have to be investigated based on heterogeneous subsurface formation since the homogeneity assumption of this formation is not valid. Over the past twenty years, stochastic approach and Monte Carlo technique have been utilized very efficiently to understand the groundwater flow behavior. However, these techniques require lots of computational and numerical efforts according to the various researchers' comments. Therefore, utilizing new techniques with much less computational efforts such as Artificial Neural Network (ANN) in the prediction of the stochastic behavior for the groundwater based on heterogeneous subsurface formation is highly appreciated. The current paper introduces the ANN technique to investigate and predict the stochastic behavior of a well draw down in a confined aquifer based on subsurface heterogeneous hydraulic conductivity. Several ANN models are developed in this research to predict the unsteady two dimensional well draw down and its stochastic characteristics in a confined aquifer. The results of this study showed that ANN method with less computational efforts was very efficiently capable of simulating and predicting the stochastic behavior of the well draw down resulted from the continuous constant pumping in the middle of a confined aquifer with subsurface heterogeneous hydraulic conductivity.

• Korean Journal of Organic Agriculture
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• v.19 no.spc
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• pp.92-95
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• 2011

The initial investment of rice cultivation by mechanical technique was high. This was only due to the cost of planting machine. We analysed the overall cost (without machine cost) and benefits of the two methods, it manifested that the mechanical method is very much beneficial over traditional rice cultivation technique. We observed that the requirement of soil, irrigation water, number of seeds etc. decreased in mechanical cultivation technique while net income increase by 13.07% with 80% government subsidy. Furthermore, the initial rooting was quicker, growth and development of pot raised seedlings was better than the traditional technique. Hence, this technique can give better return to the farmers with the help of government subsidy.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2001.10a
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• pp.246-251
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• 2001

This study is aimed to develop system that can export height automatically with Hierarchical Delaunay Triangulation and finally provide profile of hydraulic channel using 3D terrain geometry model. In this study, by using the object-oriented technique, we developed the traverse and cross-section design system of agricultural facilities, which maintain a consistency in the irrigation design process. This system can design the traverse and cross-section profile for the line type facilities. The results of this study, as for the design based on geography, after carrying out the modeling by using TIN of which employs Delaunays algorithm, it was found that the latitudinal design of the facility is feasible. And, as for the formulation of TIN, we obtained more precise result from using contour, stream, and road data rather than using the contour by itself.

• Journal of Korean Neurosurgical Society
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• v.29 no.6
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• pp.826-831
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• 2000

The major indication of endoscope in neurosurgical field is intraventricular procedures. Recently, it can be used selectively in the intraaxial mass lesion associated cavity. For example, cystic mass, with liquefied necrosis, and blood clot can be approached with this technique. The authors present its usage in brain abscess ruptured into lateral ventricle. The neuroendoscope was introduced into abscess cavity through stereotactic guidance, the pus was then removed through continuous irrigation and suction under direct video visualization. The intraventricular pus was also cleaned through gentle, direct endoscopic irrigation and suction. The postoperative clinical course was uneventful. Brief overview is given for this intraaxial neuroendoscopic procedure.

• Journal of Korea Water Resources Association
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• v.42 no.4
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• pp.281-295
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• 2009

This study estimates the value of irrigation water in Korea using an economic programming model that is constructed with all the resource endowment constraints, technology restrictions and policy variables. The variability and uncertainty of water resource endowment are incorporated into the model through the chance-constrained technique. Solving the profit maximization problems with gradually reduced water endowments, we derive a series of shadow values of irrigation water. It has been found that uncertainty in water supply raises the damage from water loss, and the marginal damage increases in water loss.

• Environmental Engineering Research
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• v.11 no.4
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• pp.194-200
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• 2006

Recently, the population growth, industrial and agricultural development are rapidly undergoing in the Lower Rio Grande Valley (LRGV) in Texas. The Lower Rio Grande Valley (LRGV) composed of the 4 counties and three of them are interesting for Non-point and point source pollutant modeling: Starr, Cameron, and Hidalgo. Especially, the LRGV is an intensively irrigation region, and Texas A&M University Agriculture Program and the New Mexico State University College of Agriculture applied irrigation district program, projects in GIS and Hydrology based agricultural water management systems and assessment of prioritized protecting stream network, water quality and rehabilitation based on water saving potential in Rio Grande River. In the LRGV region, where point and non-point sources of pollution may be a big concern, because increasing fertilizers and pesticides use and population cause. This project objective seeks to determine the accumulation of non-point and point source and discuss the main impacts of agriculture and environmental concern with water quality related to pesticides, fertilizer, and nutrients within LRGV region. The GIS technique is widely used and developed for the assessment of non-point source pollution in LRGV region. This project shows the losses in $kg/km^2/yr$ of BOD (Biological Oxygen Demand), TN (total Nitrogen) and TP (total phosphorus) in the runoff from the surface of LRGV. Especially, farmers in Cameron County consume a lot of fertilizer and pesticide to improve crop yield net profit. Then, this region can be created as larger nonpoint source area for nutrients and the intensity of runoff by excess irrigation water. And many sediment and used irrigation water with including high nutrients can be discharged into Rio Grade River.

• Magazine of the Korean Society of Agricultural Engineers
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• v.29 no.3
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• pp.125-137
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• 1987

The purpose of this paper is to examine some difficulties in water management of agricultural reservoirs in Korea, for there are approximately more than 15,000 reservoirs which are now being utilized for the purpose of irrigation, along with the much amount of expenses and labors to be invested against droughts and floods periodically occurred. Recently, the effective use of water resources in the agricultural reservoirs with a single purpose, is becomming multiple according to the alterable environment of water use. Therefore, the task to allocate agricultural water rationally and economically must be solved for the multiple use of agricultural reservoirs. On the basis of the above statement, this study aims at suggesting the rational method of water management by introducing an optimal technique to allocate the water in an existing agricultural reservoir rationally, for the sake of maximizing the economic effect. To achieve this objective, a reservoir, called "0-Bongje" as a sample of the case study, is selected for an agricultural water development proiect of medium scale. As a model for the optimum allocation of water in the multi-purpose use of reservoirs a linear programming model is developed and analyzed. As a result, findings of the study are as follows : First, a linear programing model is developed for the optimum allocation of water in the multi-purpose use of agricultural reservoirs. By adopting the model in the case of reservoir called "O-Bongje," the optimum solution for such various objects as irrigation area, the amount of domestic water supply, the size of power generation, and the size of reservoir storage, etc., can be obtained. Second, by comparing the net benefits in each object under the changing condition of inflow into the reservoir, the factors which can most affect the yearly total net benefit can be drawn, and they are in the order of the amount of domestic water supply, irrigation area, and power generation. Third, the sensitivity analysis for the decision variable of irrigation which may have a first priority among the objects indicate that the effective method of water management can be rapidly suggested in accordance with a condition under the decreasing area of irrigation. Fourth, in the case of decision making on the water allocation policy in an existing multi-purpose reservoir, the rapid comparison of numerous alternatives can be possible by adopting the linear programming model. Besides, as the resources can be analyed in connection with various activities, it can be concluded that the linear programing model developed in this study is more quantitative than the traditional methods of analysis. Fifth, all the possible constraint equations, in using a linear programming model for adopting a water allocation problem in the agricultural reservoirs, are presented, and the method of analysis is also suggested in this study. Finally, as the linear programming model in this study is found comprehensive, the model can be adopted in any different kind of conditions of agricultural reservoirs for the purpose of analyzing optimum water allocation, if the economic and technical coefficients are known, and the decision variable is changed in accordance with the changing condition of irrigation area.

• Restorative Dentistry and Endodontics
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• v.24 no.3
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• pp.490-494
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• 1999

The aim of this in vitro study was to investigate the coronal leakage of obligate anaerobes into root canals obturated with two different techniques. 48 extracted human teeth with straight, single root canals were prepared with crown-down technique with Profile under copious irrigation until the master apical file was size 40. The teeth were divided randomly into experimental groups (40 teeth) and control groups (8 teeth). In the experimental groups, 20 teeth were obturated with lateral condensation and other 20 teeth were obturated with continuous wave technique with System B. Coronal leakage of two root canal filing technique was evaluated using anaerobic bacterial leakage model with Fusobacterium nucleatum(ATCC 25586) for 60 days. The results were as follows 1. The incidence of bacterial leakage of experimental groups was 65% in group 1 (lateral condensation) and 60% in group 2 (continuous wave technique with System B). This difference was not statistically significant (P>0.05). 2. There was no statistically significant difference(P>0.05) in leakage score between group 1 (lateral condensation) and group2 (continuous wave technique with System B).

• Clinical and Experimental Reproductive Medicine
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• v.15 no.1
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• pp.1-9
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• 1988

The contraception practice rate in Korea has steadily increased from 9% in 1964 to 72% in 1987. Accordingly, natural increase rate of population declined from 28.4 per 1,000 in 1964 to 12.4 per 1,000 in 1987. Notably in recent years, the acceptance of surgical contraception services has sharply increased in this country. Now the author analyzes various factors influencing successful vasectomy and vasovasostomy based on his experience in performing more than 8,000 vasectomies and 1,000 vasovasostomies during the past 25 years. These various factors consist of preoperative screening interview, surgical vasectomy technique, vas irrigation technique, open-ended vasectomy, complications from vasectomy, sperm granuloma formation, spermatogenesis and steroidogenesis after vasectomy, immunological consequences after vasectomy, prostatic diseases and vasectomy, late post-vasectomy syndrome, psychological effects after vasectomy, and success rates of vasovasostomy. Besides, the author makes more comments on the results of the clinical trials on new approaches to reversible vas occlusion technique with a new device of Intravasal Thread and to reversible suppression of spermatogenesis with long-acting sex hormones.

• Restorative Dentistry and Endodontics
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• v.24 no.2
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• pp.399-407
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• 1999

Apical extrusion of canal debris is occurred inadvertently during root canal preparation and this could produce interappointment discomfort or postinstrumentation pain. The purpose of this study was to investigate the influence of canal preparation methods on the apical extrusion of canal debris by means of comparing the amounts of apically extruded debris with several kinds of instrumentation methods. In the first experiment, 40 incisors were divided into four groups of 10 each. They were instrumented using one of the four techniques: Step-back, crown-down pressureless technique with stainless steel K-files, engine-driven instrumentation with Quantec series 2000, and Profile .04 taper series 29. Root canal irrigation was done with 2.52% sodium hypochlorite solution. In the second experiment, 80 incisors were divided into five groups of 16 each and instrumented using step-back, crown-down pressureless technique with stainless steel K-files, engine-driven instrumentation such as Quantec SC, Quantec LX, and Profile .04 taper series 29 No irrigation procedure was performed in this second experiment. Extruded debris from each tooth was collected in a container and weighed by the use of an electronic balance after desiccation. With or without canal irrigation, step-back technique produced significantly more amount of apical debris than the other groups (p<0.05). However, there was no significant difference among crown-down pressureless technique, engine-driven instrumentation with Quantec LX, Quantec SC, or Profile. Therefore, either by hand or engine-driven instrumentation, it is concluded that to minimize apical debris, techniques using reaming motion of files should be applied rather than filing motion.