• Title/Summary/Keyword: concrete composite

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Estimation of Seismic Performance and Earthquake Damage Ratio of Existing Reinforced Concrete Buildings in Japan (일본의 기존 철근콘트리트건물의 내진성능 및 지진피해율의 평가)

  • 이강석;이리형
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.13 no.1
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    • pp.63-74
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    • 2000
  • The main objective of this paper is to apply as the basic data for development of a methodology to discuss the future earthquake preparedness measures in Korea by investigating the concept and applicabilities of the Japanese Standard for Evaluation of Seismic Performance of Existing RC Buildings developed in Japan among the methodologies of all the countries of the world. This paper describes the seismic performance, Is-index, of existing RC buildings in Tokyo, Japan evaluated by the Japanese Standard, also the relationships between Is-index distribution of existing RC buildings in Tokyo and that of Shizuoka and Chiba Prefecture reported already in reference[4][5][6] are investigated. And from the comparison with Is-index to buildings damaged by earthquakes experienced in Japan, the damage ratio due to severe earthquake of 3 districts mentioned above is estimated based on the probabilistic point of view. The results of this study can be utilized to identify urgently required earthquake preparedness measures with highest priority in existing RC buildings, and the methodology to evaluate the seismic performance of existing RC buildings in Japan, statistics analysis method and the methodology to estimate earthquake damage ratio based on the probabilistic point of view shown in this study can be recommended to develop a methodology to discuss the future earthquake preparedness measures in Korea.

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A Study on the Evaluating Method the most Favorable Mixture Proportion of Blended Fine Aggregate for Effective Application of Recycled Aggregate (재생골재의 효율적인 활용을 위한 혼합잔골재의 최적배합평가방법에 관한 연구)

  • Han, Cheon-Goo;Yoon, Gi-Won;Lee, Gun-Cheol;Park, Yong-Kyu
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.2 no.1
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    • pp.113-119
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    • 2006
  • It is now established that more than two types of blended aggregate have beneficial effects on quality and supply of concrete in the long run. However, studies on blended aggregate have not widely been progressive and the evaluation method of its most favorable mixture proportion is still needed. Therefore this study investigated the most favorable mixture proportion through the physical experiment of fresh and hardened state's cement mortar, in response to three types of composite ratio, natural fine aggregate(Ns), crushed fine aggregate(Cs) and recycled fine aggregate(Rs). Test showed that increase of blending ratio of Ns and Cs improved fluidity of mot1ar. For the properties of compressive and flexural strength, mortar blending Ns and Cs properly, exhibited similar value to one using only Cs, while mortar mixing Rs showed lower strength value as less as 6% of control one. Mortar using only Rs exhibited the largest drying shrinkage value. In addition, even thought it is not a clear quantitative analysis, technical-imaging-skill presenting the most favorable mixture proportion 3-dimensionally is proposed in this research, in order to notify the proportion easily.

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Geographical research trends on tourism resources (觀光資源에 대한 地리的 硏究動向)

  • ;;Kwon, Yongwoo;Kim, Sunhee
    • Journal of the Korean Geographical Society
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    • v.29 no.2
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    • pp.202-215
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    • 1994
  • This research aims to introduce the theoretical basis of the studies of tourism resources, by review the research trends of tourism resources in the geography field. The geographical approaches to tourism resouces can be subdicided into 3 categories according to the subject. First, the classification of tourism resource types and the approach on the spatial distribution may be enumerated. This subject has been the object of the most interest and discussion to the geographers for tourism up to now. And from the viewpoint of contents, it has been developed by classifying the types of tourism resoures, which is based on the establishment of the range and standard of tourism resources and the spatial classification of types based on the distribution feature of the area. Second, the approach about cognition, preference and interpretation on the tourism resources as the background to induce tourism phenomenon and decide the tourism destination. Judging from the fact that most of this subject is starting from the behavioural study and that the right understanding and interpretation of tourism resource is the important factor to decide the preference degree of tourists, we have to have much interest about the field of tourism geoaraphy. Third, the development of tourism resources which is showing the active study recently and its influence and effect attendant upon it may be enumerated. Today, as the economic value of tourism is become important internationally, tourism resources are recognized as the important factor to induce the industrialization of tourism. And in the series of analytical studies related to it the interest has been transferred from the economic benefit analysis attendant upon tourism development including tourism resource and to the cultural, educational, environmental and psychological influence, etc. As the result of composite examination, for the geographical studies about tourism resources, the spatial scale and the contents are being subdivided and specialized. And in the side of subject and method of study, it is developing into the positive study based on the concrete data and the measuring and analytical frame.

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A study on Dohoe towns Kyonggi Province of the late Chosun Dynasty (朝鮮後期 京畿地方의 都會硏究)

  • ;Jang, Seung Il
    • Journal of the Korean Geographical Society
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    • v.29 no.2
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    • pp.183-200
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    • 1994
  • This research aims to introduce the theoretical basis of the studies of tourism resources, by review the research trends of tourism resources in the geography field. The geographical approaches to tourism resouces can be subdicided into 3 categories according to the subject. First, the classification of tourism resource types and the approach on the spatial distribution may be enumerated. This subject has been the object of the most interest and discussion to the geographers for tourism up to now. And from the viewpoint of contents, it has been developed by classifying the types of tourism resoures, which is based on the establishment of the range and standard of tourism resources and the spatial classification of types based on the distribution feature of the area. Second, the approach about cognition, preference and interpretation on the tourism resources as the background to induce tourism phenomenon and decide the tourism destination. Judging from the fact that most of this subject is starting from the behavioural study and that the right understanding and interpretation of tourism resource is the important factor to decide the preference degree of tourists, we have to have much interest about the field of tourism geoaraphy. Third, the development of tourism resources which is showing the active study recently and its influence and effect attendant upon it may be enumerated. Today, as the economic value of tourism is become important internationally, tourism resources are recognized as the important factor to induce the industrialization of tourism. And in the series of analytical studies related to it the interest has been transferred from the economic benefit analysis attendant upon tourism development including tourism resource and to the cultural, educational, environmental and psychological influence, etc. As the result of composite examination, for the geographical studies about tourism resources, the spatial scale and the contents are being subdivided and specialized. And in the side of subject and method of study, it is developing into the positive study based on the concrete data and the measuring and analytical frame.

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Load Distribution Factors for Two-Span Continuous I-Girder Bridges (2경간 연속 I-형교의 하중분배계수)

  • Back, Sung Yong;Shin, Gi Su
    • Journal of Korean Society of Steel Construction
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    • v.19 no.2
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    • pp.233-245
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    • 2007
  • Previous finite element studies have shown that AASHTO Standard load distribution factor (LDF) equations appear to be conservative for longer spans and larger girder spacing, but too permissible for short spans and girder spacing. AASHTO LRFD specification defines the distribution factor equation for girder spacing, span length, slab thickness, and longitudinal stiffness. However, this equation requires an iterative procedure to correctly determine the LDF value due to an initially unknown longitudinal stiffness parameter. This study presents a simplified LDF equation for interior and exterior girders of two-span continuous I-girder bridges that does not require an iterative design procedure. The finite element method was used to investigate the effect of girder spacing, span length, slab thickness, slab width, and spacing and size of bracing. The computer program, GTSTRUDL, was used to idealize the bridge superstructures as the eccentric beam model, the concrete slab by quadrilateral shell elements, steel girders by space frame members, and the composite action between these elements by rigid links. The distribution factors obtained from these analyses were compared with those from the AASHTO Standard and LRFD methods. It was observed through the parametric studies that girder spacing, span length, and slab thickness were the dominant parameters compared with others. The LRFD distribution factor for the interior girder was found to be conservative in most cases, whereas the factor for the exterior girder to be unconservative in longer spans. Furthermore, a regression analysis was performed to develop simplified LDF formulas. The formulas developed in this study produced LDF values that are always conservative to those from the finite element method and are generally smaller than the LDF values obtained from the AASHTO LRFD specification. The proposed simplified equation will assist bridge engineers in predicting the actual LDF in two-span continuous I-girder bridges.

Flexible Unit Floor Plan of Off-Site Construction Housing Considering Long-Lasting Housing Certification System (장수명주택 인증을 고려한 OSC공법 주택의 가변형 평면계획 연구)

  • Lee, Ji-Eun;Roh, Jeong-Yeol;Kwon, Soo-Hye;Kim, Seung-Mo
    • Land and Housing Review
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    • v.12 no.4
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    • pp.103-117
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    • 2021
  • With the current rapid changes in population and technology, the long-lastig housing certification system is a means of prolonging the physical and functional lifespan of a building. The certification requires differentiation between the structure and infill elements to allow for variability and ease of repairs. This works well with prefabricated houses so this study investigated the possibility of applying the long-lastig housing certification requirements to apartment construction using off-site construction (OSC) methods focused on the installation of bathrooms (plumbing and toilet) that differ from the traditional wet method. This study examined three different sized floor plans at 22 m2, 46 m2, and a combined one resulting in 69 m2. The larger 69 m2 plan utilized a removeable non-load bearing wall to increase flexibility in the layout of the floorplan. The apartments are constructed of steel reinforced concrete composite columns on a 9 m × 10.5 m grid with integrated slabs. The exterior and interior infill walls are all non-load bearing with some containing plumbing. This separation of the structure and infill walls can help meet some of the criteria in the long-lastig housing certification, particularly with the ease of repairs. Technologies that facilitate the replacement of infill elements that contain plumbing and other building services can benefit the nation by reducing carbon emissions and therefore tax incentives should be introduced to increase the adoption of the proposed construction methods.

Flexural Strengthening Effects of RC Beam Reinforced with Pre-stressing Plate (긴장을 가한 보강 플레이트로 보강된 RC 보의 휨보강 효과)

  • Ha, Sang-Su
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.23 no.1
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    • pp.171-178
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    • 2019
  • Fiber-reinforced polymer (FRP) composites have proved to be reliable as strengthening materials. Most of existing studies used single types of FRP composites. Therefore, in this experimental study, carbon FRP sheet, aramid FRP sheet, and hybrid FRP plate including glass fibers were fabricated, and the effect of pre-stressed FRP composites on flexural strengthening of reinforced concrete (RC) beams was investigated. In total, eight RC beam specimens were fabricated, including one control beam (specimen N) without FRP composites and seven FRP-strengthened beams. The main parameters were type of FRP composite, the number of anchors used for pre-stressing, and thickness of FRP plates. As a result, the beam strengthened with pre-stressed FRP plate showed superior performance to the non-strengthened one in terms of initial strength, strength and stiffness at yielding, and ultimate strength. As the number of anchors and thickness of FRP plate (i.e., amount of FRP plates) increased, the strengthening effect increased as well. When hybrid FRP plates were pre-stressed, the strengthening effect was higher in comparison with pre-stressed single type FRP plate.

Characteristics of Compressive Strength Development of High Strength Cement Composites Depending on Its Mix Design (고강도 시멘트 복합체의 배합조건에 따른 압축강도 발현 특성)

  • Jeong, Yeon-Ung;Oh, Sung-Woo;Cho, Young-Keun;Jung, Sang-Hwa;Kim, Joo-Hyung
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.9 no.4
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    • pp.585-593
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    • 2021
  • This study investigates the compressive strength of high-strength cement composites with 64 mixture designs and 2 curing conditions. The cement composites were designed with varying water-to-binder ratios, silica fume content to cement, and binder content per unit volume of cement composite to explore compressive strength development depending on its mix design. An increase in the water-to-binder ratio decreased the compressive strength of the composites, having consistency with the trend in normal concrete. The compressive strength increased with ages at an ambient curing temperature, but it was not identified at high-temperature curing. The compressive strength development was negligible in case that silica fume content to OPC is 15%~25%, but a decrease in the con ten t below 15% reduced compressive stren gth. It was more obvious in the specimen of low water-to-binder ratio. The specimen with 840kg/m3 of binder content per unit volume had the highest compressive strength in this study, and the decrease in binder content reduced the compressive strength of high strength cement composites in low silica fume content.

A Study on the Ecological Characteristics and Changes of the Shigeru Ban Exhibition Space (시게루 반 전시공간의 생태적 특성과 변화 연구)

  • Tian, Hui;Yoon, Ji-Young
    • The Journal of the Korea Contents Association
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    • v.22 no.2
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    • pp.147-161
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    • 2022
  • This study examined changes in the ecological characteristics and design characteristics of Ban's exhibition space in three representative temporary exhibition halls and three permanent exhibition halls designed by Ban Shigeru since 2000. Through the investigation of the concepts and characteristics of ecological architecture, the design characteristics of exhibition space, the analysis framework of the design characteristics of exhibition space and the design elements of ecological architecture is obtained. The analysis results show that there are big changes between the temporary exhibition space and the permanent exhibition space in terms of building scale, space composition, function, materials and technology. On the one hand, the temporary exhibition space used recyclable materials, such as paper tubes, containers to be assembled on site into a single-layer space focused on display. The assembly method was simple and the construction period was short. After the exhibition, the exhibition space were dismantled. The materials were either transported to the next display site or recycled and reused. On the other hand, the permanent exhibition space used reinforced concrete as the main structure, and used a large amount of wood and glass materials to construct a multi-layered composite cultural space that separated the exhibition space and the leisure space. In terms of ecological characteristics, the building materials of the temporary exhibition space were recycled and no industrial wastes were generated after the demolition. The permanent exhibition hall uses eco-friendly wood for the roof and walls, so it is easy to replace and repair. Both types of exhibition halls are changing ecological architecture in a more sustainable direction by saving resources and energy through natural light and ventilation.

A Study on the Feasibility and Operational Directions for Establishing a Specialized Library for Comics and Webtoons in Cheongju City (청주시 만화·웹툰 특화도서관 신규 조성 타당성 및 운영방향에 관한 연구)

  • Younghee Noh;Seung-Jin Kwak;In-ho Chang;HyoJung Sim
    • Journal of Korean Library and Information Science Society
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    • v.54 no.4
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    • pp.55-83
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    • 2023
  • In this study, we propose the establishment of a specialized comic and webtoon library within the newly constructed library in Cheongju City. The aim is to create the library as the ultimate multi-cultural space, contributing to the enhancement of local residents' information utilization skills and future competencies. To achieve this, we conducted a foundational survey and current status analysis of a comic and webtoon specialized library, based on which we put forward a plan for its development. The research results yield the following outcomes: First, we provide concrete justifications and feasibility for the establishment of a comic and webtoon specialized library in Cheongju City. Second, we offer specific proposals for the vision, mission, roles, and functions of the comic and webtoon specialized library. Based on these research findings, if a comic and webtoon specialized library is constructed in Cheongju City, it has the potential to become a local landmark and serve as a unique cultural and tourist resource. Furthermore, by providing facilities and resources for various information services related to comic and webtoon creation and experiences, it can contribute to nurturing talents that lead the way in future industries.