• 한국안전학회지
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• 제27권1호
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• pp.26-31
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• 2012

Wood-plastic composites represents a growing class of materials used by the residential construction industry and furniture industry. In this study, the effect of flame retardants on the flammability and mechanical properties of wood flour-high density polyethylene(HDPE) composites were studied. we were manufactured wood flour-HDPE composites by modular intermeshing co-rotating twin screw extruder with L/D ratio of 42. The flame retardant properties were used limiting oxygen index(LOI) and mechanical properties were measured by universal testing machine(UTM). The Morphological analysis of composites were analyzed by Scanning electron microscope(SEM). It was found that Ammonium polyphosphate can effectively reduce the flammability of the wood flour-HDPE composites. Marginal reduction in the mechanical properties of the composites was found with addition of flame retardants. SEM images showed that the coupling agent improved wood flour-HDPE interfacial bonding.

• Steel and Composite Structures
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• 제24권1호
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• pp.113-128
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• 2017

This paper highlights a study undertaken on the free vibration of a precast steel-concrete composite slab panel for track support. The steel-concrete composite slab track is an evolvement from the slab track, a form of ballastless track which is becoming increasingly attractive to asset owners as they seek to reduce lifecycle costs and deal with increasing rail traffic speeds. The slender nature of the slab panel due to its reduced depth of construction makes it susceptible to vibration problems. The aim of the study is driven by the need to address the limited research available to date on the dynamic behaviour of steel-concrete composite slab panels for track support. Free vibration analysis of the track slab has been carried out using ABAQUS. Both eigenfrequencies and eigenmodes have been extracted using the Lanczos method. The fundamental natural frequencies of the slab panel have been identified together with corresponding mode shapes. To investigate the sensitivity of the natural frequencies and mode shapes, parametric studies have been established, considering concrete strength and mass and steel's modulus of elasticity. This study is the world first to observe crossover phenomena that result in the inversion of the natural orders without interaction. It also reveals that replacement of the steel with aluminium or carbon fibre sheeting can only marginally reduce the natural frequencies of the slab panel.

• Steel and Composite Structures
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• 제25권4호
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• pp.427-442
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• 2017

This paper presents unprecedented damped oscillation behaviours of a precast steel-concrete composite slab panel for track support. The steel-concrete composite slab track is an innovative slab track, a form of ballastless track which is becoming increasingly attractive to asset owners as they seek to reduce lifecycle costs and deal with increasing rail traffic speeds. The slender nature of the slab panel due to its reduced depth of construction makes it susceptible to vibration problems. The aim of the study is driven by the need to address the limited research available to date on the dynamic behaviour of steel-concrete composite slab panels for track support. Free vibration analysis of the track slab has been carried out using ABAQUS. Both undamped and damped eigenfrequencies and eigenmodes have been extracted using the Lancsoz method. The fundamental natural frequencies of the slab panel have been identified together with corresponding mode shapes. To investigate the sensitivity of the natural frequencies and mode shapes, parametric studies have been established, considering concrete strength and mass and steel's modulus of elasticity. This study is the world first to observe crossover phenomena that result in the inversion of the natural orders without interaction. It also reveals that replacement of the steel with aluminium or carbon fibre sheeting can only marginally reduce the natural frequencies of the slab panel.

• 한국주거학회논문집
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• 제26권5호
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• pp.97-104
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• 2015

This paper aims to discuss the concept of resilience in floating housing, to investigate the resilient features of floating houses & to review the possibility of floating housing as a new form of resilient living, and to suggest some reference ideas for the planning and design of floating housing projects. Resilient features of the floating house can be summarized as the buoyant characteristics for natural disasters, the easy employment & potential use of renewable and nearly self-sufficient energy systems in locations subject to limited energy sources, the movability, mobility, long life, water recycle system, prefabrication and modular construction with the potential for reduced environmental impact. Additional benefits include the potential for a peaceful and comfortable atmosphere due to direct connections with nature, good relationship with neighbors, a solid social spirit of unity, and sense of security. Considering the resilient features of floating house at a time of serious climate change requires a new paradigm, and floating/amphibious/floatable housing has great possibility as a new form of resilient living.

• 한국지진공학회논문집
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• 제17권2호
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• pp.79-88
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• 2013

Steel plate concrete (SC) composite structure is now being recognized as a promising technology applicable to nuclear power plants as it is faster and suitable for modular construction. It is required to identify its dynamic characteristics prior to perform the seismic design of the SC structure. Particularly, the damping ratio of the structure is one of the critical design factors to control the dynamic response of structure. This paper compares the criteria for the damping ratios of each type of structures which are prescribed in the regulatory guide for the nuclear power plant. In order to identify the damping ratio of SC shear wall, this study made SC wall specimens and conducted experiments by cyclic lateral load tests and vibration tests with impact hammer. During the lateral loading test, SC wall specimens exhibited large ductile capacities with increasing amplitude of loading due to the confinement effects by the steel plate and the damping ratios increased until failure. The experimental results show that the damping ratios increased from about 6% to about 20% by increasing the load from the safe shutdown earthquake level to the ultimate strength level.

• Nuclear Engineering and Technology
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• 제53권3호
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• pp.741-751
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• 2021

There has been a deep interest in trying to find better-performing fuel clad motivated by the desire to decrease the likelihood of the reactor barrier failure like what happened in Fukushima in recent years. In this study, the effect of move towards accident tolerant fuel (ATF) cladding as the most attracting concept for improving reactor safety is investigated for SMART modular reactor. These reactors have less production cost, short construction time, better safety and higher power density. The SiC and FeCrAl materials are considered as the most potential candidate for ATF cladding, and the results are compared with Zircaloy cladding material from reactor physics point of view. In this paper, the calculations are performed by generating PMAX library by DRAGON lattice physics code to be used for further reactor core analysis by PARCS code. The differential and integral worth of control and safety rods, reactivity coefficient, power and temperature distributions, and boric acid concentration during the cycle are analyzed and compared from the conventional fuel cladding. The rod ejection accident (REA) is also performed to study how the power changed in response to presence of the ATF cladding in the reactor core. The key quantitative finding can be summarized as: 20 ℃ (3%) decrease in average fuel temperature, 33 pcm (3%) increase in integral rod worth and cycle length, 1.26 pcm/℃ (50%) and 1.05 pcm/℃ (16%) increase in reactivity coefficient of fuel and moderator, respectively.

• Steel and Composite Structures
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• 제4권5호
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• pp.385-402
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• 2004

Nearly 400 composite railway bridge decks of a new kind belonging to the trough type with U-shaped cross section have been constructed in Belgium over the last fifteen years. The construction of these bridge decks is rather complex with the preflexion of precambered steel girders, the prestressing of a concrete slab and the addition of a 2nd phase concrete. Until now, they have been designed with a classical computation method using a pseudo-elastic analysis with modular ratios. Globally, they perform according to the expectations but variability has been observed between the measured and the computed camber of these bridge decks just after the transfer of prestressing and also at long-term. A statistical analysis of the variability of the relative difference between the measured camber and the computed camber is made for a sample of 36 bridge decks using no less than 10 variables. The most significant variables to explain this variability at prestressing are the ratio between the maximum tensile stress reached in the steel girders during the preflexion and the yield strength and the type of steel girder. For the same sample, the long-term camber under permanent loading is computed by two methods and compared with measurements taken one or two years after the construction. The camber computed by the step-by-step method shows a better agreement with the measured camber than the camber computed by the classical method. The purpose of the paper is to report on the statistical analysis which was used to determine the most significant parameters to consider in the modeling in order to improve the prediction of the behaviour of these composite railway bridge decks.

• 콘크리트학회논문집
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• 제26권4호
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• pp.533-543
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• 2014

최근 들어, 지하주차장과 같은 모듈화 건물에 프리캐스트 콘크리트와 현장타설 콘크리트가 함께 사용되는 복합공법의 사용이 증가하고 있다. 일반적으로 프리캐스트 콘크리트는 공장에서 선 제작되기 때문에 재료의 효율성을 극대화하기 위해 프리텐션을 도입하여 사용한다. 현행 구조기준이 긴장력이 가해진 단일 단면의 전단 강도식은 제시하지만 긴장력이 가해진 프리캐스트와 현장타설 콘크리트 합성단면의 전단강도식은 제시하지 못하고 있는 실정이다. 따라서 긴장력이 가해진 합성 부재의 전단강도 실험을 통해 긴장력이 전단강도에 미치는 영향과 합성부재의 전단강도 산정시 고려해야할 사항에 대해 알아보았다. 변수로는 콘크리트의 면적비, 긴장재의 긴장력, 전단 경간비, 그리고 전단철근비를 고려하였다. 실험 결과를 분석해보면, 전단강도는 긴장력 크기와 긴장력이 가해진 단면의 면적비가 커질수록 증가하였고 전단경간비가 증가할수록 감소하였다.

• 정보처리학회논문지A
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• 제14A권2호
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• pp.107-116
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• 2007

본 논문에서는 Reed-Muller 전개식에 의한 다치 논리 회로의 구성에 관한 한 가지 방법을 제시하였다. 먼저, Perfect Shuffle 기법과 Kronecker 곱에 의한 다치 논리함수의 입출력 상호연결에 대하여 논하였고, GF(4)의 가산회로와 승산회로를 이용하여 다치 Reed-Muller 전개식의 변환행렬과 역변환행렬을 실행하는 기본 셀을 설계하였다. 이 기본 셀들과 Perfect Shuffle과 Kronecker 곱에 의한 입출력 상호연결 방법을 이용하여 다치 Reed-Muller 전개식에 의한 다치 논리 회로를 구현하였다. 제시된 다치 Reed-Muller 전개식의 설계방법은 모듈구조를 기반으로 하여 행렬변환을 이용하므로 동일한 함수에 대하여 타 방법과 비교하여 간단하고 회로의 가산회로와 증산회로를 줄이는데 매우 효과적이다. 제안된 다치 논리회로의 설계방법은 회선경로 선택의 규칙성, 간단성, 배열의 모듈성과 병렬동작의 특징을 가진다.

• 한국멀티미디어학회논문지
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• 제11권5호
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• pp.703-709
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• 2008

컴파일러의 구성 방법론은 파싱 기법의 정립과 자동화 도구의 개발을 통해 많은 발전을 이루었으며, 이를 통해 다양한 컴파일러를 효과적으로 제작할 수 있는 환경이 마련되었다. 특히, 최근에는 임베디드/모바일 기기의 사용과 콘텐츠 산업이 활성화되고 있으며, 이에 따라 각 시스템과 콘텐츠에 적합한 컴파일러 개발 요구가 늘어나고 있다. 컴파일러의 모듈화와 자동적인 구성을 통해 이러한 수적인 요구는 해결되고 있지만, 개발도구로서의 컴파일러를 최적화하기 위해서는 경험적인 방법론의 사용과 이에 따른 매우 큰 비용이 필요하다. 본 논문에서는 LR 파서의 특징을 분석하여, 불필요한 reduce 행동을 경감할 수 있는 파싱기법을 제시한다. 개선된 파싱 기법은 파싱과정에서 lookahead/상태 정보와 도달 가능한 리덕션 골의 정보를 이용하여 연속적인 reduce를 하나의 reduce로 변환하여 효율성을 높인다. 또한, 임베디드 ANSI C컴파일러의 전단부에 적용하여 실제 모바일 콘텐츠 대한 파싱 성능을 분석하였다.