• Journal of Korean Society on Water Environment
• /
• v.29 no.4
• /
• pp.504-513
• /
• 2013

Water quality trends for major tributaries (66 sites) in the Yeongsan River basin of Korea were examined for 12 parameters based on water quality data collected every month over a period of 12 months. The complex data matrix was treated with multivariate analysis such as PCA, FA and CA. PCA/FA identified four factors, which are responsible for the structure explaining 78.2% of the total variance. The first factor accounting 27.3% of the total variance was correlated with BOD, TN, TP, and TOC, and weighting values were allowed to these parameters for grade classification. CA rendered a dendrogram, where monitoring sites were grouped into 5 clusters. Cluster 2 corresponds to high pollution from domestic wastewater, wastewater treatment and run-off from livestock farms. For grade classification of tributaries, scores to 10 indexes were calculated considering the weighting values to 3 parameters as BOD, TN and TP which were categorized as the first factor after FA. The highest-polluted group included 10 tributaries such as Gwangjucheon, Jangsucheon, Daejeoncheon, Gamjungcheon, Yeongsancheon. The results indicate that grade classification method suggested in this study is useful in reliable classification of tributaries in the study area.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2011.05a
• /
• pp.212-216
• /
• 2011

현재 하천 건천화에 따른 수생태계 교란 및 수질악화 등의 근본적인 문제가 발생하고 있으며, 최근 정부의 저탄소 녹색성장기조에 따라 조성되고 있는 신도시, 소규모 및 대규모 택지개발사업의 경우는 환경 친화적인 단지조성 요구에 부응하기 위해 기존 도심하천의 복원 및 인공하천의 녹색성장을 고려한 친환경적 생태하천으로 조성하고자 하는 다양한 노력이 시도되고 있으나 안정적인 생태복원의 수원확보 방안을 마련하지 못해 실제 설계가 반영되지 못하고 있다. 또한, 조성하고자 하는 소하천 혹은 실개울 등의 수질보전 및 생태계 보호 등 하천이 본래의 기능을 유지할 수 있도록 생태하천유량을 확보하는 다양한 기술들이 개발되어 있지만, 공사 유형과 주변 환경에 적합한 생태하천유량 확보 방안을 선정할 수 있는 비구조적 대책마련이 부족한 실정이다. 이러한 실정과 문제점을 고려해 볼 때, 조성하고자 하는 도시 내 자연하천 및 인공하천 조성 등 수변환경을 고려한 단지조성에 맞는 생태하천유량 확보 방안 및 평가에 대한 연구가 단계적으로 이루어져야 할 것이다. 따라서 본 연구에서는 생태하천유량 확보와 하천수질 개선이 필요한 특정 지역 또는 다양한 유형의 공사 지구 내 하천이 정상적인 기능을 수행할 수 있도록 적용 가능한 생태하천유량 확보 방안들과 수리해석 모델인 HEC-RAS(River Analysis System), 생태하천유량 산정 모델인 PHABSIM(Physical HABitat SIMulation)을 연계한 물리서식처 평가 모듈을 개발하고, 이를 기초로 가중치부여매트릭스 평가(국토해양부, 2006) 기법을 적용한 최적의 생태하천유량 확보 방안과 수질개선 방안을 제시해 줄 수 있는 의사결정지원 시스템을 구축 하고자 한다. 본 연구에서 개발된 최적의 생태하천유량 확보 방안 도출을 위한 의사결정지원 시스템의 활용으로 필요유량은 물론, 기준을 만족하는 수질의 확보가 절실히 요구되는 중 소규모 하천에 실질적으로 적정수질의 생태하천유량을 확보함으로서 하천으로서의 역할을 위한 본 기능의 회복과 동시에 소하천, 도심하천 및 인공하천 등 중 소규모 수계의 수문순환을 정상화하여 하천의 지속 가능한 개발과 관리가 효율적으로 이루어지도록 하는데 이용될 수 있을 것으로 예상되어진다.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.3
• /
• pp.100-109
• /
• 2019

Maintainability indicates the extent to which maintenance can be done easily and quickly. The consideration of maintainability is crucial to reduce the operation and support costs of weapon systems, but if the maintainability is evaluated after the prototype production is done and necessitates design changes, it may increase the cost and delay the schedule. The evaluation should verify whether maintenance work can be performed, and support the designers in developing a design to improve maintainability. In previous studies, the maintainability index was calculated using the graph theory at the early design phase, but evaluation accuracy appeared to be limited. Analyzing the methods of evaluating the maintainability using fuzzy logic and 3D modeling indicate that the design of a system with good maintainability should be done in an integrated manner during the whole system life cycle. This paper proposes a method to evaluate maintainability using SysML-based modeling and simulation technique and fuzzy logic. The physical design structure with maintainability attributes was modeled using SysML 'bdd' diagram, and the maintainability was represented by an AHP matrix for maintainability attributes. We then calculated the maintainability using AHP-based weighting calculation and fuzzy logic through the use of SysML 'par' diagram that incorporated MATLAB. The proposed maintainability model can be managed efficiently and consistently, and the state of system design and maintainability can be analyzed quantitatively, thereby improving design by early identifying the items with low maintainability.

• Journal of Korea Soil Environment Society
• /
• v.1 no.1
• /
• pp.89-102
• /
• 1996

An integrated model is presented to describe underground flow and mass transport, using a multicomponent multiphase approach. The comprehensive governing equation is derived considering mass and force balances of chemical species over four phases(water, oil, air, and soil) in a schematic elementary volume. Compact and systemati notations of relevant variables and equations are introduced to facilitate the inclusion of complex migration and transformation processes, and variable spatial dimensions. The resulting nonlinear system is solved by a multidimensional finite element code. The developed code with dynamic array allocation, is sufficiently flexible to work across a wide spectrum of computers, including an IBM ES 9000/900 vector facility, SP2 cluster machine, Unix workstations and PCs, for one-, two and three-dimensional problems. To reduce the computation time and storage requirements, the system equations are decoupled and solved using a banded global matrix solver, with the vector and parallel processing on the IBM 9000. To avoide the numerical oscillations of the nonlinear problems in the case of convective dominant transport, the techniques of upstream weighting, mass lumping, and elementary-wise parameter evaluation are applied. The instability and convergence criteria of the nonlinear problems are studied for the one-dimensional analogue of FEM and FDM. Modeling capacity is presented in the simulation of three dimensional composite multiphase TCE migration. Comprehesive simulation feature of the code is presented in a companion paper of this issue for the specific groundwater or flow and contamination problems.