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선형분극법을 이용한 보통포틀랜드시멘트 콘크리트의 임계염화물량
김홍삼,정해문,안태송 한국세라믹학회 2007 한국세라믹학회지 Vol.44 No.9
The results of evaluating steel corrosion in concrete containing chloride content of various levels indicated that the more chloridecontent in concrete leads to the lower potential and higher corrosion current density. However, the open circuit potential of steel variedwith time and exposure condition, and the corelation between the open circuit potential and corrosion current density was not obvious.In order to determine the critical threshold content of chloride of steel corrosion in concrete, the concept of average corrosion currentdensity was employed. The range of critical chloride content in portland cement concretes was about 1.56~1.77% (Cl, %, wt ofcement content) along with water-cement ratio, and higher water-cement ratio resulted in reduction in critical threshold chloridecontent.
빅데이터 분석 기반의 오피니언 마이닝을 이용한 정보화 사업 평가 분석
김홍삼,김종수 한국산업경영시스템학회 2018 한국산업경영시스템학회지 Vol.41 No.1
Current evaluation practices for IT projects suffer from several problems, which include the difficulty of self-explanation for the evaluation results and the improperly scaled scoring system. This study aims to develop a methodology of opinion mining to extract key factors for the causal relationship analysis and to assess the feasibility of quantifying evaluation scores from text comments using opinion mining based on big data analysis. The research has been performed on the domain of publicly procured IT proposal evaluations, which are managed by the National Procurement Service. Around 10,000 sets of comments and evaluation scores have been gathered, most of which are in the form of digital data but some in paper documents. Thus, more refined form of text has been prepared using various tools. From them, keywords for factors and polarity indicators have been extracted, and experts on this domain have selected some of them as the key factors and indicators. Also, those keywords have been grouped into into dimensions. Causal relationship between keyword or dimension factors and evaluation scores were analyzed based on the two research models-a keyword-based model and a dimension-based model, using the correlation analysis and the regression analysis. The results show that keyword factors such as planning, strategy, technology and PM mostly affects the evaluation result and that the keywords are more appropriate forms of factors for causal relationship analysis than the dimensions. Also, it can be asserted from the analysis that evaluation scores can be composed or calculated from the unstructured text comments using opinion mining, when a comprehensive dictionary of polarity for Korean language can be provided. This study may contribute to the area of big data-based evaluation methodology and opinion mining for IT proposal evaluation, leading to a more reliable and effective IT proposal evaluation method.