• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.8
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• pp.3704-3712
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• 2012

Recently, antiwashout underwater concrete has been increasingly used for marine foundations of long span bridges. However, to shorten the construction period of antiwashout underwater concrete used in marine foundations, high fluidity antiwashout underwater concrete should be manufactured largely improving fluidity than the previous one. Thus, the objective of this experimental research is to suggest optimum mix proportions of high fluidity antiwashout underwater concrete. For this purpose, concrete specimens containing ground granulated blast furnace slag were manufactured according to the dosage of antiwashout admixture for unit binder contents of 550 and 600kg/$m^3$, respectively. And then, their quality performances such as slump flow, setting time, underwater segregation resistance, and ratio of compressive strength were evaluated according to the related specification of Korea Concrete Institute. It was observed from the test results that the minimum dosage of antiwashout admixture was necessary to satisfy the related specification.

• Information Systems Review
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• v.23 no.3
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• pp.159-176
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• 2021

Obviating user churn is a prominent strategy to capitalize on online games, eluding the initial investments required for the development of another. Extant literature has examined factors that may induce user churn, mainly from perspectives of motives to play and game as a virtual society. However, such works largely dismiss the service aspects of online games. Dissatisfaction of user needs constitutes a crucial aspect for user churn, especially with online services where users expect a continuous improvement in service quality via software updates. Hence, we examine the relationship between a game's quality management and its user base. With text mining and survival analysis, we identify complaint factors that act as key predictors of user churn. Additionally, we find that enjoyment-related factors are greater threats to user base than usability-related ones. Furthermore, subsequent quasi-experiment shows that improvements in the complaint factors (i.e., via game patches) curb churn and foster user retention. Our results shed light on the responsive role of developers in retaining the user base of online games. Moreover, we provide practical insights for game operators, i.e., to identify and prioritize more perilous complaint factors in planning successive game patches.

• Journal of the Korean Ceramic Society
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• v.39 no.10
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• pp.970-976
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• 2002

In this paper, the slump flow of the concrete, suspension, pH, corrosion effect, bleeding and the characteristics of coompressive strength were analyzed using antiwashout underwater admixture and antiwashout underwater agent+corrosion inhibitor mixed admixtures(1type). The results showed that there were no rare difference in physical properties but in the results of rapid corrosion tests there were lots of corrosion inhibitor ratio differences between concrete using only antiwashout underwater admixture and the corrosion inhibitor mixed(1type). In the case of only antiwashout underwater admixture 5.4%, the case corrosion inhibitor mixed(1type) 0.07%, the Antiseawater of the concrete which uses the Corrosion Inibitor Mixed(1type) appeared highly.

• Journal of the Korean Ceramic Society
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• v.39 no.10
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• pp.963-969
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• 2002

In this studies, methly celluloes was used as antiwashout admixture and when considering the physical properties and economical efficiencies of Underwater Concrete as the results of making an experiencing slump flow, flow loss, setting time, suspension and pH also compressive strength and underwater/an air compressive strength ratio according to the adding amount changes 5, 7, 9, 11 kg/$m^3$ to Underwater Concrete of melamine superplasticizer, the using amount of melamine superplasticizer in Underwater Concrete approximately represents 9 kg/$m^3$.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.878-882
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• 2008

경제성장에 따른 도시화 현상으로 경작지나 녹지와 같은 투수 지표면이 대단위 주택단지나 도로, 상업지구 등의 도시시설 및 산업화에 따른 공장시설과 같은 불투수 지표면으로 변화되어 도시의 불투수 지표면의 구성비가 증가되므로 이로 인해 침투량과 증발산량이 감소하며 지하수 유출량을 감소된다. 또한 도시유역의 조도계수의 감소로 도달시간이 단축되어 첨두홍수량이 증가하게 되는 등 도시유출특성이 변화되어 홍수피해가 빈번하게 발생하고 있다. 본 연구에서는 광주광역시 서구 상무지구를 대상으로 불투수면적비의 변화에 따라 유출모의를 실시하였다. 유출모의를 위한 대상지구의 유역 및 관로 시스템의 제원은 수치지도와 관망도를 이용하여 유역을 구분한 후 배수 관망, 유입구 제원, 맨홀 등 관로시스템 자료 및 유역의 지표면과 지하 배수시설 및 토지이용상태를 조사하여 유역의 불투수지역(Impervious area) 및 투수지역(pervious area)으로 구분하였다. 불투수면적비에 따른 유출량과 유출률, 첨두유량, 기저시간의 변화를 비교분석 하였다. 모의 값의 정확성을 판단하기 위하여 2008년에 측정한 실측자료를 통해 매개변수를 최적화를 실시하여 SWMM모형으로부터의 모의 값과 실측자료를 비교 분석 하였다.

• Annual Conference on Human and Language Technology
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• 2001.10d
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• pp.267-272
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• 2001

구(phrase) 단위 또는 문장(sentence) 단위의 연어(collocation) 정보는 자연언어 처리를 위한 단일어 또는 이중어 데이터베이스를 구축할 수 있는 중요한 기초 자료가 될 뿐 아니라, 외국어 학습에서도 어휘 단계를 넘어선 학습 자료를 제공할 수 있다. 불어는 굴절 언어(inflectional language)로서 기본형 대 굴절형의 비율이 약 1:9 정도로 비교적 굴절 비율이 높은 언어다. 또한 불어 표제어 중 95% 이상을 차지하는 불어의 동사, 명사, 형용사 중 상당한 비율이 암기해야 할 목록(list)이라는 특성을 갖기 때문에 검색과 학습에 있어 오류가 지속적으로 일어나는 부분이다. 표제어의 검색의 경우 불어 굴절 현상을 지원하는 전자 사전이 개발되어 있지만 아직까지 연어 정보에서 굴절형을 지원할 수 사전 또는 데이터베이스는 개발되어 있지 않다. 본 연구의 목적은 전자 사전과 형태소 분석기를 이용하여 굴절형 처리를 지원할 수 있는 불-한 연어 데이터베이스를 구축하는데 있다. 이를 위해 부산대학교 언어정보 연구실에서 개발한 불어 형태소 분석기 Infection와 불-한 전자 사전 Franco를 사용하였으며, 지금까지 구축된 불-한 연어 정보는 94,965 개이다. 본 고에서는 두 정보를 이용하여 불어 굴절형 정보를 분석 및 생성하는 방식 및 불-한 연어 데이터베이스 구조를 살펴 본다.

• The Korean Journal of Applied Statistics
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• v.24 no.4
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• pp.647-656
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• 2011

Incidence matrix is a useful tool for presenting incomplete block designs; however, it is inadequate to use only an incidence matrix in examining whether a certain incomplete block design becomes a balanced incomplete block design or not. We can use a structural matrix as a useful tool to show whether a certain incomplete block design becomes a balanced incomplete block design or not. We propose an augmented incidence matrix and ${\lambda}$ matrix as another tools for evaluating incomplete block designs. Through the augmented incidenc matrix and ${\lambda}$ matrix, we can ascertain whether a certain incomplete block design becomes a balance incomplete block design or not.

• Journal of Korean Society for Geospatial Information Science
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• v.14 no.2 s.36
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• pp.23-32
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• 2006

This study shows that new methodology improved the problem of unaided eye test level with the digital orthophoto technique can survey more objectively and efficiently any cadastral non-coincidence than existing prior methodologies. For applying to it, we explore eligible other methodologies, and then build up the application strategy of them. New prototype system is implemented with it. Also, we say the availability of new methodology by applying to study area. As a result, we suggest cadastral non-coincidence surveying method based on point-correspondence more objective and more efficient. As a result of comparing with old method and new on same study area for making adequacy, they hardly ever has the difference of accuracy. Constantly, cadastral non-coincidence surveying method based on point-correspondence is acceptable way on the cadastral survey.

• Polymer(Korea)
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• v.26 no.5
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• pp.575-581
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• 2002

Heterogeneous ion exchange membranes were prepared by mixing polyethylene as matrix with bead and fibrous anionic ion exchangers at different mixing ratio. Generally, ion exchange capacities were increased with increasing the ratio of the fibrous ion exchanger content. The highest ion exchange capacity of the membrane was 1.86 meq/g at 30wt% IXF (ion exchange fiber) in the membrane. The water uptake, fixed ion concentration, and ion transport number of the membrane increased with increasing the content of the fibrous ion exchanger. However, the electrical resistivity of the membrane was decreased with increasing the content of the fibrous ion exchanger. The lowest electrical resistivity of 5$\Omega$/$\textrm{cm}^2$ was observed at 30 wt%of IXF.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.19 no.2
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• pp.23-30
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• 2009

Recently, rotation symmetric Boolean functions have attracted attention since they are suitable for fast evaluation and show good cryptographic properties. For example, important problems in coding theory were settled by searching the desired functions in the rotation symmetric function space. Moreover, they are applied to designing fast hashing algorithms. On the other hand, for some homogeneous rotation symmetric quadratic functions of simple structure, the exact formulas for their Hamming weights and nonlinearity were found[2,8]. Very recently, more formulations were carried out for much broader class of the functions[6]. In this paper, we make a further improvement by deriving the formula for the Hamming weight of quadratic rotation symmetric functions containing linear terms.