The investigation was initiated with data from 27 abandoned mines along with 12 locations in Kyongbuk abandoned mines. The analyses for soil pollution by heavy metal pollutants were conducted by using correlation analysis, cluster analysis, and principal component analysis. The correlation analysis indicated that Ni and pH were highly correlated compared to those of other heavy metal ions. The principal component analyses showed that the heavy metal ions might be classified into two catagories, such as antropogenic and lithogenic components. The cluster analysis was also clearly divided by two groups. The respective two groups might be Pb-Zn-Cd-Cu and As-Hg-Ni.

The present study is to investigate the effect of wave-structure interaction such as wave oscillation. The theoretical method is based upon the linear diffraction theory obtained by the boundary element method. The water depth and incident wave period in fluid region are assumed to be constant. To investigate the wave interaction due to offshore structures, the numerical program has been developed and the simulation has been carried out by varying the conditions of distance and width of offshore structures. This study can effectively be utilized for safety assessment to various breakwater systems and layout of offshore breakwater in the ocean and coastal field. It can give information for the safety to construct offshore structure and revetment in coastal region.

The risk assessment for heavy metal pollutions were analyzed by using statistical techniques including correlation and cluster analyses. The contamination data in this investigation obtained were from the Chungcheongnam-do abandoned mines. The descriptive statistical analysis showed that the values of Pb and Zn were relatively higher than other heavy metal values. The detection of heavy metals by distance from abandoned mines within 1,000m were mostly As, Cd, Pb, and Zn. It was noted, especially, that Zn was even detected at 4,000m The results of coefficient correlation showed that Zn to Cd was the highest values. The cluster and dendogram analyses were generated. The results showed the two clear groups by heavy metal characteristics.

The present study is to estimate the effect of wave height affecting at the front face of breakwater systems due to specification of submarine trench such as distance from breakwater to dredged area and width of dredge. The wave diffraction field, which is important hydraulic factor in the ocean, is considered to be two dimensional(2D) plane and the configuration of the submarine dredge on the sea bed designated by single horizontal long-rectangular pit system according to the various specific conditions of dredged locations. The numerical simulation is performed by using Green function based on the boundary integral equation and meshed at moving boundary conditions. The results of present numerical simulations are illustrated by applying the normal incidence. It is shown that the ratios of wave height at the front face of breakwater was varied by dependance of distant from breakwater to dredged area and width of dredge. It means that, when the navigation channel or pit breakwater is dredged on seabed, engineers have to consider the specification of dredge. This study can effectively be utilized for safety assessment to various breakwater systems in the ocean field and provided for safety construction of offshore structure.

An evaluation of the concrete strength has very important meaning in the maintenance and the structural safety. The reliability of ferroconcrete building is weakening and enlarging the life is strongly demanded due to the early deterioration of concrete. Like this social demand, concrete strength presumption is being indirectly executed using the result in parallel with the concrete pouring by material age. This data is usually different as concrete poured practically and the way of hardening and curing. Although existing concrete strength presumption formula is proposed, the material used and the concrete strength is different. And as a matter of remicon, the concrete strength varies according to the site and the way of curing. So the objective of this research is strength evaluation of the structural body concrete according to the concrete pouring and curing temperature change seasonally after using the system which evaluates the structural body concrete strength which is applied the transparent junction-separation mold that is presented. Also there is an objective to present the fundamental data for the constructional quality technique proposal of the structural body concrete developed in relation to field specimen and the strength evaluation method by non-breaking.

Fe(C) nanocapsules were prepared by the chemical vapor condensation(CVC) process using the pyrolysis of iron Their characterizations were studied by means of X-ray diffraction, X-ray photoelectron spectrometer and transmission electron microscopy. The long-chained Fe(C) nanocapsules hav-ing the mean size of under 70 nm could be obtained below in different gas flow rates. The particle size of the powders was increased with increasing decomposition temperature, but it was decreased with increasing CO gas flow rate. The Fe powders produced at consisted of three layers of phases, but it had two phase core-shell structure which consited of phase of core and graphite of shell at

Fe nanopowders were successfully synthesized by plasma arc discharge (PAD) process using Fe rod. The influence of chamber pressure on the microstructure was investigated by means of X-ray Diffraction (XRD), Field Emission Scanning Electron Microscope (FE-SEM), Transmission Electron Microscopy (TEM) and X-ray Photoelectron Spectroscopy (XPS). The prepared particles had nearly spherical shapes and consisted of metallic cores (a-Fe) and oxide shells (FeO), The powder size increased with increasing chamber pressure due to the higher dissolution and ejection rate of H and gas density in the molten metal.

The magnetic Nd-Fe-B powders were prepared by a thermochemical method, consisting of the processes of spray-drying, debinding, milling, H-reduction, Ca-reduction, and washing. The optimum process conditions were studied by microstructural and thermal analysis. The resultant Nd-Fe-B powder was spherical with the size of 1 . Effects of the process parameters of each step on the microstructure of the powders were investigated, and their magnetic properties were evaluated

지구 온난화에 기인한 기후변화로 인해 산지에서의 토석류가 많이 발생하고 있으며, 최근 우리 나라 및 세계의 여러 나라에서 많은 피해가 발생되고 있다. 따라서, 토석류에 기인한 토사재해의 특성 및 발생량 등을 분석하여 토석류 방지대책에 적용하려는 노력이 대두되고 있으며, 이러한 방지대책을 설정하기 위해서는 계획 토석류의 분석이 필요하다. 본 연구는 집중호우와 세립사가 섞인 토사유동혼합체가 산지에서 유하할 때 토석류 계획을 세우기 위한 토석류의 거동을 분석한 것이다. 수치해석 모델은 질량보존 및 운동량 보존에 관한 방정식에 기초하여 유한차분법을 이용한다. 수치해석 모델을 적용하기 위하여 소단을 갖는 다양한 형태의 수로가 적용된다. 소단 길이가 작을수록 토석류가 하류단에 도착한 직후 유량과 유동심에서 서지가 발생하고, 소단 길이가 길어질수록 크게 감소한다. 토사농도의 경우 약 16초가 되는 지점에서 고저차가 큰 변곡점이 발생하며, 이는 토석류가 하류단에 도달한 직후에는 고농도의 토사가 고유량의 유체 혼합물과 섞여 하류로 흘러가기 때문에 피해를 가중시키게 된다. 공급유량이 증가한 상태에서는 소단길이가 짧아질수록 유량과 유동심의 곡선이 불안정한 상태를 나타냈고, 약 10초 이후에는 고유량과 고유동심의 분포를 갖는 fluctuation이 15초 가량 지속되는 것으로 나타난다. 이는 집중호우의 영향권에 있는 산지에서 토석류가 산지 하류부에 도달한 이후 어느 정도 시간이 지나도 토석류의 유량과 유동심이 감소하지 않고, 고저의 불안정한 상태로 하류부로 계속해서 유하한다는 것을 의미한다. 본 연구의 결과는 강우 변화에 따른 비탈면 하류단에서의 토사 유체 혼합물의 토석류에 의한 재해방지의 계획을 위한 좋은 정보를 제공하며, 사면 안정시의 대책에 필요한 계획 설정에 정보를 제공한다.

기후변화에 기인한 집중호의 영향으로 산지에서 토석류를 비롯한 토사재해가 해마다 발생하고 있다. 대분의 경우 토석류 등의 재해는 산지에서 일어나는 것으로 한정하기 쉬우나, 토석류와 산사태가 발생하여 인근의 하천에 유입되면 고농도의 탁수가 혼합된 것과 동일한 효과가 발생하여, 수질에 악영향을 미친다. 이와 마찬가지로 연안에 위치한 산지에서 토석류가 발생하면, 발생된 토석류는 바다와 연결된 하천을 따라서 바다로 유입되게 된다. 이와 같은 고농도의 토석류가 바다에 유입되면 주변의 수질은 오염되어 생태계에 악영향을 미친다. 본 연구에서는 바다와 연결된 강원도 오십천 유역의 산지를 연구대상지역으로 하여, 유역 내 산지에서 토석류가 발생하였을 때 이에 따른 토석류의 거동을 모의하였다. 바다와 연결된 하구를 원점으로 하여 10 km의 거리에 대해서 토석류의 유량과 토석류의 유동심을 모의 하였다. 산지유역의 상류부에서 토석류가 발달함에 따라 침식과 퇴적이 반복되어 일어나고 있다. 모의결과 하구에서의 토사유출량은 114,216 ㎥으로 나타났다. 이와 같은 연구를 발생시켜 실제현상에 대한 예측능력을 강화시킨다면 산지와 연결된 하구부 또는 하천에서의 토석류에 의한 2차 재해를 방지하는데 효과적일 것으로 판단된다.

Fuzzy algorithm of automatic control for dissolved oxygen(DO) concentration in the aeration tank of an activated sludge process is proposed. Among variables repirometry and air flowrate are selected as significant input factors and the relationship with DO is estimated using a multiple regression model. The DO concentration and the amount of repirometry are fuzzified and the fuzzy rule base are determined. Using the fuzzy algorithm, the change of amount of air flowrate are determined and the change of amount of DO is derived.