• Proceedings of the Korean Radioactive Waste Society Conference
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• 2012.05a
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• pp.365-366
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• 2012

• Journal of the Korean Recycled Construction Resources Institute
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• v.1 no.1
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• pp.67-75
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• 2013

Recently, the interest is increasing about the exposed concrete, accordingly, exposed concrete is expanding the use. However, concrete structures is difficult to apply the general concrete for exposed concrete, due to complex section and compact reinforcement, increasingly. Therefore, in this paper, for application of high fluidity concrete as exposed concrete, exposed high fluidity concrete using fly ash and lime stone powder was manufactured and observed quality property(fluidity properties, mechanical properties and Surface Properties) of exposed high fluidity concrete. The experiments are based on the OPC and LSP10, was evaluated Impact on the quality of concrete according to mixing ratio of FA(0, 10, 15 and 20). As a result, fluidity properties, mechanical properties and Surface Properties of exposed high fluidity concrete were satisfied to requirement conditions, fluidity and surface finishability was improved depending on mix of fly ash and limestone powder. Through this, we utilize of basic research data for development of high fluidity concrete for exposed concrete.

• Journal of the Society of Naval Architects of Korea
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• v.35 no.3
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• pp.54-61
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• 1998

This paper presents a prediction method of natural frequencies of vertical hull girder vibration based on design sensitivity analysis in case of design modification and the variation of loading condition. The resented method premises the vibration analysis by the transfer matrix method. Governing sensitivity equation is derived from the direct differentiation of state vector and transfer matrix to parameters and its transfer over all the hull girder elements. Derivatives of natural frequencies and mode shapes are determined by two trial calculation of the governing equation. Using the derivatives, the changes of natural frequencies and mode shapes can be predicted when mass and stiffness parameter's are changed. As results, it is possible to optimize ship structure as well as to avoid troublesome calculation in hull girder vibration analysis rationally and efficiently. To verify the accuracy and efficiency of the resented method numerical results obtained by both the sensitivity analysis and the ordinary reanalysis far a real ore/bulk carrier in case of the change of mass and stiffness parameters are compared.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.13 no.1
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• pp.87-95
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• 2000

The two eigenvalues (elastic critical load and natural frequency of lateral vibration) of sinusoidally tapered bats with simply supported ends were determined by the finite element method. For the convenience of structural engineers who are engaged in the structural design or vibration analysis of tapered beam-columns, eigenvalue coefficients were expressed by simple algebraic equations. The validity of each algebraic equation was confirmed by the value of unity for each correlation coefficient. The influence of axial thrust on the lateral vibration frequency was also investigated. For this purpose, the axial thrust was increased successively and the corresponding frequency was calculated. The approximate linear relationship between the axial thrust and the square of the frequency was confirmed lot each of the tapered members.

• Journal of the Korea Concrete Institute
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• v.13 no.3
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• pp.294-300
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• 2001

The effectiveness of bottom ash on the mechanical and physical properties of Controlled Low-Strength Material(CLSM) is investigated in this study, CLSM is defined by the ACI Committee 229 as a cementitious material that is in a flowable state at the time of placement and having a specified compressive strength of 83 kgf/$\textrm{cm}^2$ or less at the age of 28 days. This study was undertaken on the use of bottom ash as a fine aggregate in CLSM. Four different levels of bottom ash with fly ash contents, 25%, 50 %, 75%, 100%, are investigated. Laboratory test results conclude that inclusion of bottom ash increases the demand for mixing water in obtaining the required flow. However, the sand was reduced because it was adjusted to maintain a constant total volume. Miかe proportions were developed for producing CLSM at three 28-day strength levels: removal with tools (less than 7 kgf/$\textrm{cm}^2$), mechanical means (less than 20 kgf/$\textrm{cm}^2$), and power equipment (less than 83 kgf/cm\`). The physical and mechanical properties supports the concept that by-product bottom ash can be successfully used in CLSM.

• 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.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2010.10a
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• pp.103-105
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• 2010

국내외 해운 환경 변화를 반영한 새로운 발전 전략의 수립이 필요한 시점에서 본 연구는 고유가와 선복과잉 상황 하에서 경제속력으로 감속운항을 위한 선박추가 투입과 환적의 경제성 효과에 대해 실제비용을 바탕으로 사례분석하고 이를 근거로 해운기업이 소유한 가용선박의 활용방안을 제시한다.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2002.11a
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• pp.141-146
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• 2002

폐가스-공기 열교환 방식의 열교환기는 각종 산업용 요ㆍ로나 보일러 등에서 배출되는 폐열을 예열공기로 회수하여 연소용공기로 사용하는 에너지 절약방법으로 현재와 같이 고유가가 지속되고, 전 세계적인 공업화에 의한 고도성장과 생활수준의 향상에 따른 에너지 수요 증가, 에너지자원의 매장량의 한계 및 지역적 편중, 산유국이 밀집되어 있는 중동지역의 불투명한 정세를 미루어 볼 매 석유수급, 고유가의 불안요인은 더욱 증가할 것으로 추정된다.(중략)

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.10a
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• pp.171-176
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• 1993

초정밀 공작기계의 구조물은 Sub-micron의 운동정밀도를 갖추어야 초정밀기계로서의 기능이 유지된다. 특히 가공기의 베드구조물은 구동요소간의 상대 위치를 정.동적으로 규정 해주는 중요한 기본구조물이므로 고강성, 고쇠감성,열안정성, 경년변화에 대한 치수의 안정성등의 성능이 요구되며, 이를위해 공간적인 형상 설계 및 구조재의 선정에 고도의 기술이 필요하다. 따라서 본 연구는 낮은 고유진동수의 특성을 갖으면서 하중의 설치높이의 변화에서도 고유진동수가 일정히 유지되고 또한 구조물의 중심변화에 대한 수평조절이 가능하면서 자동제어가 가능한 공기스프링을 초정밀 가공기의 방진시스템으로 활용방안에 대하여 연구하였다.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2003.05a
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• pp.185-190
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• 2003

산업체 등에서 사용되고 있는 가스들중에서 일반적인 가스들과는 달리 위험한 가스(heavy gas)들은 누출사고시에 이들 고유한 확산과 계층화(stratification)방식에 의해 높은 위험성을 유발시키고 있다. 이러한 가스의 누출확산사고들과 일반적인 가스누출사고들의 비교는 그 사실들을 증명해주고 있다. 이런 사실에 의해 위험한 가스확산에 대한 실험과 고유특성을 고려한 확산모델의 개발이 여러 관점에서 진행되고 있으며, 이들의 중요성은 이미 세계적으로 의미를 부여하고 있다.(중략)