• Journal of Mechanical Science and Technology
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• 제19권8호
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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.

• 한국유기농업학회지
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• 제19권spc호
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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.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2001년도 학술발표회 발표논문집
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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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• 제29권6호
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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.

• 한국수자원학회논문집
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• 제42권4호
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• pp.281-295
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• 2009

본고는 경제적 최적화모형인 확률제약 계획모형법을 이용하여, 농업용수 부존량 감소에 따른 농업이윤의 감소분을 계측하고 이를 통해 농업용수의 경제적 가치를 분석하고자 한다. 이를 위해 국가 전체 농업자원배분을 최적화 모형으로 구축하고, 농업용수를 포함하는 자원부존제약조건과, 각 상품의 가격이 형성되는 시장조건, 국제무역 및 관련정책변수의 영향들을 반영하고, 용수의 경우 그 이용량이 연도별로 불안정할 수 있다는 것까지 반영한다. 농업용수감소량이 농업부문 이윤에 미치는 영향을 시나리오를 주어 분석하면, 농업용수의 톤당 경제적 가치는 $303{\sim}1,093$원/$m^3$의 분포를 가지는 것으로 나타난다. 동일한 양의 용수량이 줄어들더라도 용수의 공급이 불안정할수록 경제적 가치 손실이 크며, 아울러 많은 양의 용수손실이 발생할수록 경제적 손실이 커 용수감소의 한계피해는 용수감소량의 증가 함수인 것으로 파악된다.

• Environmental Engineering Research
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• 제11권4호
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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.

• 한국농공학회지
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• 제29권3호
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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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• 제24권3호
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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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• 제15권1호
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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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• 제24권2호
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• pp.399-407
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• 1999

근관 형성중 잔사의 치근단 정출은 치근단 조직의 반응을 유발하여 동통과 부종을 일으키며 치유를 지연시킬 수 있다. 본 연구의 목적은 수종의 기구와 방법을 사용하여 근관을 형성하고 이에 따른 근관 잔사의 치근단 정출량을 비교함으로써 잔사의 정출을 최소화 할 수 있는 기구 조작법을 알아보고자 하는 것이다. 120개의 발거된 사람의 하악 절치에서 근관형성중 치근단으로 정출되는 잔사의 양을 비교하였다. 첫 번째 실험에서는 40개의 치아를 10개씩 4군으로 나누어 2.52% 치아염소산나트륨용액으로 근관을 세척하면서 다음의 4방법 중 하나를 이용하여 근관을 형성하였다. 수동 스테인레스 스틸 K-화일을 이용하여 step-back technique, crown-down pressureless technique으로 근관을 형성하였고 전동 니켈 티타늄 기구로는 Quantec SC series 2000과 Profile .04 taper series 29를 이용하여 근관을 형성하였다. 두 번째 실험에서는 80개의 치아를 16개씩 5군으로 나누고 근관 세척에 의한 잔사의 치근단 정출 영향을 배제하고자 근관 세척을 시행하지 않고 근관을 형성하였다. 이 때에는 첫 번째 실험의 방법중 Quantec SC series 2000 대신에 Quantec SC 및 Quantec LX를 이용하여 근관을 형성하였고 나머지는 첫 번째 실험과 동일하게 시행하였다. 각 치아로부터 정출되는 잔사를 용기에 모아 24 시간동안 건조시킨 후 전자 저울로 무게를 측정, 비교하여 다음과 같은 결과를 얻었다. 근관 세척을 시행한 경우와 시행하지 않은 경우 공히 step-back technique을 사용한 군에서는 다른 군에 비해 현저히 많은 량의 치근단 정출 잔사가 나타났다. 그러나, crown-down technique을 이용하여 근관 형성한 군과 수종의 Ni-Ti 파일을 이용하여 전동으로 근관 형성한 군들 사이에는 정출 잔사량에 유의한 차이가 나타나지 않았다. 따라서, 본 실험에 사용된 수동 및 전동 기구의 종류는 근관 잔사의 치근단 정출에 영향을 미치지 않는 것으로 생각되며, 근관잔사의 치근단 정출을 최소화하기 위해서는 수동 및 전동 기구 공히 step-back 방법에 의한 filing 동작보다는 crown-down technique의 reaming 동작을 사용하여 근관을 형성하는 것이 바람직하다고 사료된다.