• Title/Summary/Keyword: Old concrete

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A Study on Sustainable Greenspace based on Urban Remodeling Design of an Old Apartment Building

  • Myung Sik Lee;Seung Ryeol Min
    • International Journal of High-Rise Buildings
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    • v.12 no.2
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    • pp.179-193
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    • 2023
  • It is undeniable that urban greenspace is the soul of a city. Conventional urban greenspace such as parks, community gardens, playgrounds etc. located within a city reduce the negative effects of pollution, play a major role in the survival of the urban ecosystem, and promote healthy lifestyles. Today, 55% of the world's population lives in urban areas, which is expected to increase to 68% by 2050. Projections show that urbanization and the gradual migration to urban areas combined with the fast growth of the world's population, could add another 2.5 billion people to urban areas by 2050 and almost 90% of this increase will take place in Asia(UN, 2018). As a result, many plots in the cities are and will continue to be occupied with buildings to provide residential support to the increased population. This will dangerously decrease urban greenspaces. Moreover, worldwide, food crisis, energy crisis, and social crisis is posing a great threat to the existence of mankind. Additionally, the COVID - 19 has introduced a new lifestyle where from work culture to community configuration has drastically transformed. In this scenario, residential buildings will have to serve more than just providing privacy and shelter. As urban greenspaces are being occupied by concrete residential buildings, these buildings will have to compensate for the percentage of urban green they are destroying and the issues they are imposing in the process. The goal of this thesis is to design, architecturally define and, categorize comprehensive 'sustainable Greenspace'(S.G.S) for the multi-family housing scenario. These will be different than the conventional green (veranda, rooftop green) we commonly see in residential buildings. An old, dilapidated apartment building will be the target of remodeling to fulfill the purpose of this thesis.

Experimental Study on Flexural Behavior of PSC I Girder and the Effect of External Prestressing (PSC I합성 거더의 휨 거동 및 외부 강선 보강효과에 관한 실험 연구)

  • Lee, Byeong-Ju;Park, Jae-Guen;Kim, Moon-Young;Shin, Hyun-Mock;Park, Chang-Ho
    • Journal of the Korea Concrete Institute
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    • v.19 no.6
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    • pp.755-762
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    • 2007
  • For the evaluation of the load carrying capacity of the deteriorated PSC I girder bridge in service load state and the verification of the grade to the reinforcement effect of actual bridge strengthened by external prestressing tendons, the field test using vehicles is applied widely. Because this teat was executed in elastic range, the investigation of the characteristics of behavior caused by live load is only available. And it is impossible to estimate load carrying capacity in limit state and nonlinear behavior after that a crack is appeared. In this study, the 27-year-old prestressed concrete girder bridge is used and various load tests are performed, so we evaluate the behavior characteristics of the bridge in service load state and ultimate load state, and estimate the load carrying capacity of bridge. In addition, the artificial damages are induced from cutting internal tendons, and external tendons is added to strengthen it as much as vanished internal tendons. Next we compare the damage state with the strengthening state. In case of the application of external prestressing method to PSC I girder bridge, the present experiment result may decide more exactly the load carrying capacity of actual bridge, the amount for reinforcement, and the standard of quality control etc. at reinforcement work.

Determination of Bond Strength and Fracture Energy of a Bi-material Cylinder with Peny-shaped Interface Crack by Pull-off Test (직접인장시험에 의한 원형 비부착면이 삽입된 신.구 콘크리트의 부착강도 및 파괴에너지 산정)

  • Yang, Sung-Chul;Kim, Jin-Chul;Park, Jong-Won
    • International Journal of Highway Engineering
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    • v.6 no.1 s.19
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    • pp.47-56
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    • 2004
  • To determine the pure bond strength between substrate and its overlayed concrete material, a direct pull-off test method was introduced by using a bi-material cylinder with which a penny-shaped crack was mountained at its interface. First, to evaluate the stress magnification or concentration at the interface, the energy release rates of a penny-shaped interface crack in remote tension loading on a bi-material cylinder were determined in terms of different modulus ratios and undonded area ratios(crack ratios) using a commercial finite element program. Then the energy release rates were calibrated as non-dimensional values in consideration of structural dimensions and applied forces. And to evaluate whether this new pull-off test method gives sound test results, three different sizes of unbended area ratios were incorporated along their interface in bi-material cylinders(sulphur polymer concrete + old concrete). Test results showed that all specimens were broken off at their interfaces as intended. Also the FEM analyses and test results indicated that a bi-material specimen with unbended area ratio of 0.4$\sim$0.6 is suitable for best accurate testing.

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Perceived Importance and Mathematical Interaction of 5-year-olds' Mothers according to Contents of Mathematics Education (만5세 유아 어머니의 수학교육내용별 중요성 인식 및 수학적 상호작용)

  • Kim, Ji Hyun;Kim, Jung Min
    • Korean Journal of Childcare and Education
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    • v.10 no.2
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    • pp.175-192
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    • 2014
  • The purpose of this study was to investigate the differences in perceived importance of mathematical education (perceived importance) and mathematical interaction of 5-year-olds' mothers according to contents of mathematical education. Second, we intended to examine whether mothers' understanding of purpose of mathematical education predicted on their perceived importance and mathematical interaction. Third, we analyzed relative influence between mothers' perceived effectiveness of concrete materials and worksheets on their perceived importance and mathematical interaction. The subjects consisted of 151 mothers of 5-year-olds lived in D city and K province in Korea. The results were as follows: First, mothers' perceived importance and mathematical interaction were higher in 'number and arithmetic'. Second, mothers' understanding of purpose of mathematical education predicted their perceived importance in all contents and mathematical interaction in 'number and arithmetic', 'geometry', and 'algebra'. Third, mothers' perceived effectiveness of concrete materials predicted better in most contents of mathematical education. Meanwhile, in 'number and operation', mothers' perceived effectiveness of worksheets did a predictive role in their importance awareness. These results were discussed in terms of necessity of a parent education program to provide practical information about contents and methods of mathematical education for their 5-year-old children.

The Experimental Study on The Compressive Strength of Mortar Using High Quality Recycled Fine Aggregate Produced by Sulphuric Water and Low Speed Wet Abraser (황산수와 저속습식마쇄기로 생산된 고품질 순환 잔골재의 모르타르 압축강도에 관한 실험적 연구)

  • Choi, Duck-Jin;Lee, Dae-Guen;Han, Sang-Il;Kim, Ha-Suk;Jun, Myong-Hun;Kim, Jin-Man
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.04a
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    • pp.485-488
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    • 2008
  • Recycled fine aggregate has low quality because it contains large amount of old mortar. So, its usage is limited to a lower value-add, such as the roadbed material etc. Also, alkaline water occurred from treatment process of the waste concrete is becoming the cause of environmental problem. Accordingly, this study is to develop on the high quality recycled fine aggregate produced by low speed wet abraser using sulphuric. We investigated the properties of compressive strength of the mortar which was manufactured using recycled fine aggregate containing calcined gypsum produced by earlier mentioned process. Test results indicate that mortar using recycled fine aggregate containing calcined gypsum has lowest compressive strength. It seems that low compressive strength is closely associated with the expansion of the specimen by excessive formation of ettringite.

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An Experimental Study on Reinforcement Method for Reuse of Onshore Wind Turbine Spread Footing Foundations (육상풍력터빈 확대기초의 재사용을 위한 보강방법에 관한 실험적 연구)

  • Song, Sung Hoon;Jeong, Youn Ju;Park, Min Su;Kim, Jeong Soo
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.41 no.1
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    • pp.1-11
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    • 2021
  • In order to reuse existing onshore turbine foundations, it is important to redesign and reinforce the existing foundations according to the upgraded tower diameter and turbine load. In the present study, a slab extension reinforcement method and structure details of an anchorage part were examined in consideration of the reuse of spread footings, which are the most widely used foundation type in onshore wind turbine foundations. Experiments were conducted to evaluate the load resistance performance of a reinforced spread footing according to structure details of an anchorage part. The results showed that (1) the strength of an anchorage part could be increased by more than 30 % by adding reinforcement bars in the anchorage part, (2) pile-sleeves attached to an anchor ring contributed to an increase in rotational stiffness by preventing shear slip behavior between the anchor ring and the concrete, and (3) slab connectors contributed to an increase in the strength and deformation capacity by preventing the separation of new and old concrete slabs.

A Study on Architecture and Urban Regeneration in Korea through the Perception of Body (몸의 지각론에 의한 유휴시설의 건축도시 재생에 관한 연구)

  • Hyung, Hyung-Chir;Joh, Hahn
    • Korean Institute of Interior Design Journal
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    • v.26 no.6
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    • pp.210-221
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    • 2017
  • First, we can define how our body perceives the external world and embodies its senses through the philosopher Merleau - Ponty. These philosophical orientations of Merleau-Ponty also appear to urban theorists such as Jane Jacobs, Gordon Cullen, and Juhani Pallasmaa. In other words, after the Second World War, people began to pay attention to human emotions and perceptions while opposing human rational thinking. Especially, they reject the abstract space of modernism and explore the everyday city space where the local character of the area lives. This place is a space where the collective memory of the group is shared over several generations. So, in this space, people's active perceptual system works actively. In the sense of this continuity of time, their ideas intersect with the concept of urban. Specifically, Jacobs criticizes massive development and proposes the development of a small block-based city with a commonality of old and new. In addition, we argue that urban space can be a visually interesting object through the continuous visual concept of urban theorist Cullen. In particular, he rediscovers the value of traditional urban space through visual experience between architecture and urban facilities. Finally, the architectural city theorist, Pallasmaa., criticizes the visual centrality of modern cities and thinks about the value of multidisciplinary space that can be experienced in architecture. This study examines the space of reproduction in detail on the perspective of the body philosophy and urban theorists. In other words, the play space inherits the natural city time, so when our body experiences this play space, we can actively sense and perceive the various senses. So we can invoke the active external actions of our bodies. Through the analysis of the size of the reconstruction space of the architectural city, various types of body senses and responses can be. Yoon Dongju Literary Museum, which renovated the old water tank of the city, can recognize the unfamiliar sense of body in everyday life through the traces and smells of water in the past and the restrained visuality. In addition, Seonyudo Park, which regenerates the waste water purification plant, can experience a phenomenal phenomenon through water space, old concrete and traces of steel. Finally, with the most recently played Seoul Road 7017 can experience interesting urban spaces in terms of a variety of plants, a human scale space creating movement, and a continuous visual.

A study on SiJo in Dongkwang magazine (『동광』의 시조 연구)

  • Ahn, Yeong-Gil
    • Sijohaknonchong
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    • v.44
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    • pp.57-74
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    • 2016
  • This these studies on SiJo to be published Dongkwang magazine. Dongkwang magazine was published from 1926 to 1933 but in the concrete it proceeded for three years two month. It was published a little SiJo and SiJo would reflected a phenomenon of society and a character of literature. A representative characters of the Si-Jo in substance at that time was summed up three. First it described a warmth of farm village. Expecially make full use of a sensuous description expressed a landscape of farm village. Otherwise it revealed a life of austerity in farming area. Second it reflected a phenomenon of return to their home village. People who was familiar with their country loved to come back their old home. To relax their mind and body they came back home and they pursuit romantic life. Third it was a poetry of historical retrospect. Although their country was colonial situation they longed fot their country's independence. Because of this anxiety they expressed their heart by means of old sijo. Mainly using old castle, ring, historic site they revealed a hidden feelings thst they had. It was a sorrow, an eager, remembrance etc. In spite of a poor surroundings they sang hope, romance, an possibility of independence. and so SiJo reflected the phases of the times.

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The Effect of Natural Disaster Safety Education on Young Children's Safety Problem-solving Abilities and Eco-friendly Attitudes (자연재해 안전교육이 유아의 안전문제해결사고 및 환경 친화적 태도에 미치는 영향)

  • Lim, Eun Ok;Kim, Ji Eun
    • Korean Journal of Child Education & Care
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    • v.18 no.4
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    • pp.227-245
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    • 2018
  • Objective: In this study, educational activities were organized to emphasize the importance of natural disaster safety education by reflecting the recent rapid increases in natural disasters. The study focused on story-sharing, art, and game activities to effectively conduct natural disaster safety education for four-year-old children, and in doing so, aimed to improve the children's safety problem-solving abilities and eco-friendly attitude. Methods: Based on the types of natural disasters that are handled by the Ministry of Public Administration and Security and the Chungcheongbuk-do Office of Education, earthquakes, yellow dust, heat waves, floods, typhoons, bolts of lighting, fires, snowstorms, and global warming were included as the study's educational contents, and a total 20 sessions of natural disaster safety education activities were planned. For the subjects, 20 four-year-old children at K Kindergarten attached to a school were selected as an experimental group and 20 four-year-old children at N Kindergarten attached to a school were selected as a control group. Both kindergartens were located in C City, Chungcheongbuk-do. The experimental group was instructed to perform the study's education activities, whereas the control group only carried out general activities based on the Nuri Curriculum's subjects of daily life. Results: As a result, the children in the experimental group, who received the natural disaster safety education, improved their safety problem-solving abilities and eco-friendly attitude when compared to those in the control group. This outcome proved that the natural disaster safety education conducted by the present study offers educational activities that can positively affect improvements in children's safety problem-solving abilities and eco-friendly attitude. Conclusion/Implications: Therefore, the present study is likely to provide concrete information to teachers who plan to conduct natural disaster safety education in the actual early childhood education field.

Probabilistic seismic and fire assessment of an existing reinforced concrete building and retrofit design

  • Miano, Andrea;de Silva, Donatella;Compagnone, Alberto;Chiumiento, Giovanni
    • Structural Engineering and Mechanics
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    • v.74 no.4
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    • pp.481-494
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    • 2020
  • In this paper, a probability-based procedure to evaluate the performance of existing RC structures exposed to seismic and fire actions is presented. The procedure is demonstrated with reference to an existing old school building, located in Italy. The vulnerability assessment of the building highlights deficiencies under both static and seismic loads. Retrofit operations are designed to achieve the seismic safety. The idea of the work consists in assessing the performance of the existing and retrofitted building in terms of both the seismic and fire resistance. The seismic retrofit and fire resistance upgrading follow different paths, depending on the specific configuration of the building. A good seismic retrofit does not entail an improving of the fire resistance and vice versa. The goal of the current work is to study the variation of response due to the uncertainties considered in records/fire curves selection and to carry out the assessment of the studied RC structure by obtaining fragility curves under the effect of different records/temperature. The results show the fragility curves before and after retrofit operations and both in terms of seismic performance and fire resistance performance, measuring the percent improving for the different limit states.