비점원오염은 여러가지가 있는데 그 중에서 농약에 의한 오염은 통제나 관리가 어려워서 효과적인 관리방법으로 IPM개념의 도입이 가장 적합하다고 판단되며, 미국에서 실제 적용 해본 결과 우리나라에서도 지형적 특성이나 농업형태에 따라 적용할 수 있는 가능성이 있으며 이 부분에 관한 연구가 필요하다. 농약이란 제거 또는 억제하고자 하는 생명체에 위해를 가하는 화학약품이기 때문에 다른 생명체에도 정도의 차이는 있으나 위해를 끼칠 수 있다. 이러한 농약성분들은 일정한 기간 약효를 나타내는 것이 특징인데,제품에 따라서는 자연분해가 느려서 생태계에 오랫동안 잔류하는데, 이 경우에 잔류농약이 사용목적외에 다른 생태계로 이동하여 피해를 입히고 인체의 건강에도 악영향을 미치게 된다. 이처럼 생태계뿐만 아니라 인체의 건강에 직접적으로 피해를 줄 수 있는 농약은 사용에 신중을 기하고, 되도록 사용량을 감소시켜야 하며, 환경친화형인 농약제품의 개발과 안전하고 손실이 적으며 효과적인 농약투입방법의 사용이 요구된다.

작물의 최대 수확을 위한 관개계획은 작물의 수분장력 스트래스와 삼투스트래스를 최소화 시킬 수 있도록 언제 얼마의 물을 어떤 속도로 공급해 줄 것인가를 결정하는 것이다. 이는 토양, 작물 및 대기의 여러 가지 요소를 측정하여 결정할 수 있다. 관개속도는 주로 토양의 투수계수에 의하여 결정되지만 관개시간과 양은 토양함수량과 경우에 따라서는 토양염도에 의하여 결정된다. Time Domain Reflectometry (TDR)는 한 개의 탐침으로 토양 함수량과 토양염도를 동시에 측정하는 새로운 기법이다. TDR의 측정원리와 상업용 TDR장비에 대하여 자세히 설명하였다. TDR 탐침의 간격, 직경 및 길이의 제한요소를 토양함수량과 전기전도도의 함수로 나타내었다. 토양 columm 및 현장에서의 TDR 전극 삽입과 케이블테스터의 신속한 분리기법과 토양층에 TDR 탐침을 영구히 설치하는 기법에 대하여 자세히 설명하였다.

This study was conducted to evaluate the relationships between the geotechnical properties and the CBR values of the subgrade materials used in the rural roal construction. A total of 77 Soil samples was investigated and tested from 45 agricultural and industrial sites in Kyungpook Province. The results obtained are as follows : 1. The maximum dry densities of the coarse grained soils are larger than those of the fine grained soils. The optimum moisture contents of the coarse grained soils are smaller than those of the fine grained scils. 2. The mean values of the medified CBR values of the soils classified by the USCS, are decreased in the order of GP-GM, SW-SM, GM, SC, SP-SM, ML, CL-ML. And, those classified by the AASHTO are decreased in the order of A-i-a, A-i-b, A-2-4, A-3, A-4, A-6, A-7-6. 3. As passing percentage of No.200 sieve is increased, the CBR Value of soils is decreased gradually. 4. As the optimum moisture contents of the soil is increased, the CBR values is decresed the maximum dry density of the soils increased, the CBR values increased. 5. The CBR values are decreased as Group-lndex(GI) are increased. And Activity(A) is showed no relation with the CBR values. 6. The relation ships between the modified CBR value and standand proctor compaction CBR value at 95% compaction ratio can he expressed as the following equation : Y(CERmod)= 2.3638 + 0.8922X(CBR25).

This study, a preliminary one to construction of standardized rural resources evaluation system, aimed at catching the valuing structure of rural and urban residents cn rural resources through interview. The questionnaire employed in our surveys was focussed on; opinion about the advantages and disadvantages of living in rural areas, usual impression on rural life style, viewpoint on preservation of cultural heritages and conservation of natural environments, priority item listing for improvement/development of rural village. Generally, regardless of interviewee's personal characteristics, the peaceful and comfortable life in the lovely/clean environment was indicated as a representative advantage of rural life. However, in minor aspects, there were recognizable differences by their living and thinking patterns, so, a deep and systematic study should be progressed to harmonize or integrate the pluralistic valuing trends on rural affairs in future. The valuing structure on rural resources from this study showed much more varieties according to age-and occupation-groups, while young generation strongly hold self-orii-ented and ambiguous thinking. Because this trend will grow more deeply and widely in future, the resoruces evaluation system for rural purposes should be established as a rational base for decision-making on rural development strategies.

This study was conducted to simulate long seres of synthetic monthly flows by multi-season first order Markov model with selection of best fitting frequency distribution, harmonic synthetic and harmonic regression models and to make a comparison of statistical parameters between observes and synthetic flows of five watersheds in Geum river system. The results obtained through this study can be summarized as follow. 1. Both gamma and two parameter lognormal distributions were found to be suitable ones for monthly flows in all watersheds by Kolmogorov-Smirnov test. 2. It was found that arithmetic mean values of synthetic monthly flows simulated by multi-season first order Markov model with gamma distribution are much closer to the results of the observed data in comparison with those of the other models in the applied watersheds. 3. The coefficients of variation, index of fluctuation for monthly flows simulated by multi-season first order Markov model with gamma distribution are appeared closer to those of the observed data in comparison with those of the other models in Geum river system. 4. Synthetic monthly flows were simulated over 100 years by multi-season first order Markov model with gamma distribution which is acknowledged as a suitable simulation modal in this study.

In order to investigate the characteristics of gravity drainage for geotextile, small-scale model tests for the geotextile chimney drain of earth dam which is a typical type of gravity drainage were carried out using 15 kinds of nonwoven and composite geotextiles. According to the results of this study, the drainage discharge of geotexgile drain generally increases with exponential function as hydraulic head increases and the increasing rate is greater in the coarser soil of dam material. It has a trend to increase when the construction slope of geotextile drain is steeper and the number of layers of geotextile is more. The relationship between the transmissivity of geotextile and the drainage discharge has positive correlation and the rate of increase is greater in the coarser soil. The geotextile products must be carefully selected in consideration of transmissivity of geotextile when the soil to be drained is coarser and the seepage flow is relatively high. Most of staple fiber nonwoven geotextile used in this study are found to be appropriate for drainage purpose. Among them, the composite geotextile the type of which geotextile is evaluated to be the most excellent material. But the geotextile of low permeability such as filament thermal bonded and filament spunbonded nowovens closely examined their transmissivity especially to be used for drainage function.

This paper presents the results of field experience from an experimental pavement construction on a low volume road using recycled concrete. The recycled concrete was prepared by replacing a half of coarse aggregate with recycled aggregate. Virgin natural sand was used as fine aggregate together a plasticizer and a fly ash (0.8% and 5% by wt. of cement, respectively). The load bearing capacity of the subbase made of recycled aggregate was acceptable. The length, thickness and width of the pavement were l00m, 20cm and 3m, respectively. From construction experience, it was found that workability and finishability of the recycled concrete mixture were relatively poor, but strengths were satisfactory. Flexural strength, compressive strength and elastic modulus at 28 days were 54Kg/$cm^2$, over 250Kg/$cm^2$, and 220,OOOKg/$cm^2$, respectively. The construction could be performed by hand without much difficulty. The surface was finished smoothly by wet fabric and only minor cracks were found on the surface.

This study wag performed to evaluate the engineering properties of permeable polymer concrete with stone dust and fly ash and unsaturated polyester resin. The following conclusions were drawn. 1. The highest strength was achieved by stone dust filled permeable polymer concrete, it was increased 17% by compressive strength, 188% by bending strength than that of the normal cement concrete, respectively. 2. The water permeability was in the range of 3.O76~4.152${\ell}/ cm{^2}/h$, and it was largely dependent upon the mix design. These concrete can be used to the structures which need water permeability. 3. The static modulus of elasticity was in the range of $1.15{\times} 10^5kg/cm^2$, which was approximately 53 56% of that of the normal cement concrete. 4. The poisson's number of permeable polymer concrete was in the range of 5.106~5.833, which was less than that of the normal cement concrete. 5. The dynamic modulus of elasticity was in the range of $1.29{\times} 10^5~1.5{\times} 10^5 kg/cm^2$, which was approximately less compared to that of the normal cement concrete. Stone dust filled permeable polymer concrete was showed higher dynamic modulus. The dynamic modulus of elasticity were increased approximately 7~13% than that of the static modulus. 6. The compressive strength, bending strength, elastic modulus, poisson's ratio, longitudinal strain and horizontal strain were decreased with the increase of poisson's number and water permeability at those concrete.

동일한 하천의 용전산소량(DO)을 예측하는 경우에도 사용하는 재포기계수$(K^2)$는 계산하는 공식에 따라 커다란 차이를 나타매며, 부적합한 공식의 사용에 의한 $(K^2)$의 계산은 하천의 수질관리 정책결정에 지장을 초래하므로 현장사정에 적합한 공식의 개발이 필요하다. 이러한 공식의 개발은 많은 현장측정 자료를 사용하도록 신뢰성이 높으나 현장측정은 소요되는 비용에 제약을 받기 때문에 신뢰성과 경제성을 동시에 고려한 표본의 크기의 적정규모를 산정하는 것이 필요하다. 본 연구에서는 Monte Carlo 방법에 의해 통계적으로 수출된 $(K^2)$를 사용해서, 주어진 자료에 의해 개발된 공식을 사용할 때 야기되는 오차가 $(K^2)$개수의 증가에 따라 얼마나 감소하는지를 널리 사용되는 공식 중에 Owen공식과 Churchill공식을 New Jersey에 있는 Passaic River에 적용시켜 검토하였다. 표본의 크기가 10에서 20으로 증가할 때 오차가 크게 감소하였으며 20을 넘어 증가시켰을 때에는 오차의 감소폭이 미미하였다. 초차의 감호형태와 단위측정당 소요되는 비용을 고려할 때 약 20정도의 표본의 크기가 적정수준의 규모에 판단된다. 이러한 적용사례의 결과는 회귀모델의 이론적 계산결과에 의한 오차 감소와 흡사하여 본 연구결과는 여러 가지(K2)공식과 광범위한 하천의 조건에 적용이 가능할 것이며, 본 연구에서 사용한 적정표본의 크기 산정방법은 회귀분석에 의해 실험식을 개발하는 다른 분야에도 적용이 가능하다.