• 콘크리트학회논문집
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• 제16권5호
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• pp.709-717
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• 2004

The existing AASHTO Standard Specification have some inadequacies in expressing wheel load distribution of bridge which has specific shape of curved bridge instead of straight bridge. Thus, this research presented the finite element analysis and modelling technique of prestressed concrete girder bridge having curved slab and the expression of wheel load distribution was suggested as the ratio of bending moment utilizing the result of finite element analysis of prestressed concrete girder bridge having cowed slab. The considered parameter of girder distribution expression is the curvature of slab, span length, girder space, cross beam space and number of lanes. Though the suggested girder distribution expression is generally underestimated below AASHTO Standard Specification, once the curvature of slab increases, the suggested expression gets larger than AASHTO LRFD Standard Specification.

• 한국안전학회지
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• 제30권6호
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• pp.102-109
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• 2015

In this study, on the basis of the results of the field survey and the theoretical consideration for Korean Standard Specification for concrete durability and maintenance, the following conclusions are derived. From the survey, the prediction equation of carbonation depth for the southwest region in Korea is experimentally proposed, $y_p=5.865{\sqrt{t}}$, which predicts about 60mm of the carbonation depth for the concrete structures of 100 years, a 1st class of target endurance period, under a combined deterioration environment like a marine environment. Considering that the marginal value for a carbonation depth limitation under very severely marine environment is 25mm, in accordance with the Specification, it is found that the predicting carbonation depth for the concrete cover depths, 100mm and 60mm are 63mm and 29.4mm, respectively. In conclusion, according to the equation and the Specification, it is strongly required that the reinforced concrete structures with the cover depth under 100mm have to make a protection from combined deterioration factors by any methods like a surface coating, an increment of cover depth or an application of a special concrete.

• 콘크리트학회지
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• 제11권2호
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• pp.10-27
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• 1999

• 콘크리트학회지
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• 제11권2호
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• pp.5-9
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• 1999

• 콘크리트학회지
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• 제22권1호
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• pp.26-28
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• 2010

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2006년도 정기 학술대회 논문집
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• pp.749-756
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• 2006

Because of the orthotropic elastic properties and significant two-way bending action, orthotropic plate theory may be suitable for describing the behavior of concrete filled grid bridge decks. Current AASHTO LRFD Bridge Design Specification(2004) has live load moment equations considering flexural rigidity ratio between longitudinal and transverse direction, but the Korea highway bridge design specification(2005) doesn't. The Korea highway bridge standard specification LRFD(1996) considers an orthotropic plate model with a single load to estimate live load moments in concrete filled grid bridge decks, which may not be conservative. This paper presents live load moment equations for truck and passenger car, based on orthotropic plate theory. The equations of truck model use multiple presence factor, impact factor, design truck and design tandem of the Korea highway bridge standard specification LRFD(1996). The estimated moments are verified through finite-element analyses.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 가을학술발표대회논문집
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• pp.131-132
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• 2023

In this paper, standard specification of heat curing section of cold weather concrete between Korea and China were compared. First, Korea concrete specification (KCS 14 20 40) stipulates that the application period is less than 4℃ per day or less than 0℃ per day right after pouring, but in China, the outdoor daily average temperature is less than 5℃ for five consecutive days. This is believed to be due to the difference in temperatures between Korea and China in winter. Next, in the case of Korea, KCS do not show that the concrete temperature in curing should be 5℃ or higher to prevent early frost damage and obtain the minimum required compressive strength. On the other hand, in the case of China, the specificaion does not show that the curing method is selected based on the concrete surface coefficient after considering the outdoor temperature. In addition, in Korea and China regulation, the temperature of the space during thermal curing was shown to be similar.

• 한국조경학회지
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• 제41권1호
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• pp.60-70
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• 2013

본 연구는 조경공사 표준시방서 식재공사의 분류체계, 기술방식, 품질기준의 개정시기별 변화특성을 분석하고, 국외 사례와의 비교를 통하여 개선방향을 제시하고자 하였다. 이에 본 연구의 결과 및 제언은 다음과 같다. 1. 개정을 통해 다양한 세부공종이 신설 수정되었으나 상 하위분류가 맞지 않아 시방내용이 상충되고 있으므로 비슷한 공사끼리의 재분류가 필요하다. 2. 시방서 내용을 용이하게 전달하기 위한 기술방식으로 수정이 이루어졌다. 그러나 구체성이 떨어지는 애매모호한 표현과 용어로 유지되고 있는 굴취시 뿌리분의 깊이, 지주재 강도에 관한 내용은 수정이 필요하다. 또한 표토의 채취시기, 약제 살포시기 등은 계량화될 필요가 있으며, 시방규정의 공정성을 고려하여 감독자의 지시에 따르도록 작성된 기준은 수정되어야 한다. 3. 시대적 패러다임과 사용자의 요구를 반영한 품질기준이 제 개정되었으나 구체적이지 않아 수정이 필요하며, 관련 기준들의 국외 사례를 참고하여 수목재료의 품질수준, 식재적기, 굴취시 뿌리분의 크기, 성능기준 등을 개선해야 한다. 개정을 통해 식재공사의 세부공종별 재료 및 시공방법에 대한 내용은 갖춰졌다. 그러나 구체성이 떨어지고 명확하지 않은 기준들로 시방서의 현장 활용을 저해하고 있다. 이에 표준시방서의 분류체계, 기술방식, 품질기준의 문제점 도출과 개선방향의 제시가 필요하며, 이는 향후 표준시방서 개정시 참고자료가 될 수 있다.

• 한국산업융합학회 논문집
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• 제4권4호
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• pp.419-426
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• 2001

Concrete mix proportioning is a process of selecting the right combination of many materials such as cement, fine aggregates, coarse aggregates, water, and admixtures to make concrete satisfying for specification and cost. In determining proportioning of concrete mixes, code information, specification, and the experience of experts are needed. However, all factors regarding mix proportioning factor cannot be considered. Therefore, the final acceptance depends on concrete quality control test results. The proportioning of concrete mixes and the adjustments are somewhat complicated, time-consuming, and uncertain tasks. In this paper, as a tool to predict the factor of the proportioning of concrete mixes, an artificial neural network is used. To consider the varieties of material properties, the standard mixed table of two companies of ready mixed concrete are used. The results show that neural net works is successfully applied to the prediction of concrete mix proportioning factor.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 가을학술발표대회논문집
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• pp.143-144
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• 2023

The compressive strength of concrete varies depending on various factors. Among them, based on the curing temperature, the KCS 14 20 10 Standard Specification for General Concrete calculates the nominal strength by applying the temperature correction value (Tn) based on the compressive strength of the standard cured concrete at 20±2℃ when designing the formulation strength. However, Tn is a correction value that considers only the temperature, and the correction of strength difference due to heat of hydration is not applied. Therefore, in this study, one-component and two-component concrete are mixed in the summer, structural concrete are manufactured, standard concrete specimen are manufactured, and coring is performed on the central and boundary parts of the structural concrete to calculate the correction value applied to the nominal strength by comparing the compressive strength of standard cured concrete on the 28th day of curing and the compressive strength of structural concrete on the 91st day of curing.