• Title/Summary/Keyword: Korea Land and Housing Corporation

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An Experimental Study on the Properties of Engineering and Shrinkage Cracking Reduction of Fiber Reinforced Concrete Using Recycled Fine Aggregate (섬유보강 순환잔골재 콘크리트의 공학적 특성 및 수축균열저감특성에 관한 실험적 연구)

  • Kim, Gyu-Yong;Nam, Jeong-Soo;Kim, Moo-Han;Lee, Do-Heun;Song, Ha-Young
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.4 no.3
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    • pp.82-89
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    • 2009
  • Recently, the study is progressing actively about manufacture skill of concrete for promoted recycled aggregate and concrete made into recycled aggregate in the construction production field. But, application and study about recycled fine aggregate insufficient compared to recycled coarse aggregate. So, in this study, it presents basic data for development of environmental load reduction fiber reinforcement recycled fine aggregate concrete by comparison and investigation about engineering properties and shrinkage cracking of fiber reinforcement recycled find aggregate concrete for increasing shrinkage cracking reduction and long term stability of environmental load reduction concrete used recycled fine aggregate. In the result of the study, compared to natural fine aggregate, a crack-extent increased by applying recycled fine aggregate, moreover, as a water cement ratio increased, the crack size increased, as well. In addition, it's shown that the specimen mixed with PVA and Nylon, among all kinds of fibers, showed the smallest crack size, so it's verified that the mix of fiber had an effect on decreasing crack-extent.

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Soil Chemical Property, Mortality Rates and Growth of Planting Trees from Soil Covering Depths in Coastal Reclaimed Land of Asan Area (아산지역 해안매립지의 복토높이에 따른 토양화학성, 수목 고사율 및 생장 특성)

  • Byun, Jae-Kyeong;Kim, Choon-Sig;Lim, Chae-Cheol;Jeong, Jin-Hyon
    • Korean Journal of Soil Science and Fertilizer
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    • v.44 no.3
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    • pp.502-509
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    • 2011
  • It is important to determine optimum soil covering depths for tree survival and growth because soil covering depths for establishing tree planting bases in coastal reclaimed lands are related to the costs for soil collection, transportation and land reclamation. The objectives of this study were carried out to determine optimum soil covering depths for the normal growth of planted trees in a coastal reclaimed land. The study sites were located in Asan National Industrial Complex in Pyeongtaek City, Gyeonggi-do. Four tree species (Pinus thunbergii, Chamaecyparis pisifera, Zelkova serrata, Quercus acutissima) with one hundred eighty trees of each species were planted in various depths of soil covering (no soil covering, 0.5 m, 1.5 m, 2.0 m soil covering treatments) on April 1998, and the tree growth patterns were measured on September 2000. The change of soil properties, tree mortality rate, root collar diameter and height growth were measured from each soil covering depth treatment on September 2000. Soil pH, EC, exchangeable cations ($K^+$, $Na^+$, $Ca^{2+}$, $Mg^{2+}$), anion $Cl^-$, and base saturation increased with decreased soil covering depths. The mortality rates of tree species showed decreased with increased soil covering depths. The height growth of tree species increased with increased soil covering depths. Height growth of Pinus thunbergii was significantly different between the soil covering depth below 0.5m and other three covering depths, while the growth of other species (C. pisifera, Z. serrata, Q. acutissima) was significantly higher in soil covering depths below 1.5 m than in other soil covering depth treatments. The root collar diameter growth of all tree species showed increasing trends with increased soil covering depths. It is recommended to cover the soil depths above 1.5 m to decrease mortality and to stimulate the tree growth of C. pisifera, Z. serrata and Q. acutissima, while P. thunbergii which is a salt tolerate species could be planted in the 1.0 m soil covering depth.

Estimation of Load-Settlement Curves of Embedded Piles Combining Results of End of Initial Driving and Restrike Dynamic Pile Tests (초기항타 및 재항타 동재하시험 결과를 조합한 매입말뚝의 하중-침하량 곡선 산정)

  • Seo, Mi Jeong;Park, Jong-Bae;Park, Min-Chul;Lee, Jong-Sub
    • Journal of the Korean Geotechnical Society
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    • v.36 no.7
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    • pp.15-28
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    • 2020
  • As the skin friction of an embedded pile is produced by the cement paste injected into the borehole, the skin friction cannot be evaluated by the end of initial driving test, which is conducted before the cement paste is cured. In addition, the total resistance of an embedded pile may not be properly evaluated during the restrike test if the base resistance is not fully mobilized because of the insufficient driven energy. The objective of this study is to suggest a new load-settlement curve of embedded piles by combining the results of the end of initial driving and restrike tests. Test piles are installed at fields by using the embedded pile method, and the results of the dynamic pile tests are analyzed using CAse Pile Wave Analysis Program (CAPWAP) after the end of initial driving and restrike tests are conducted. A new load transfer curve, which combines the behaviors of the pile base at the end of initial driving and of the pile shaft at the restrike, is suggested, and a new load-settlement curve is obtained. Subsequently, the resistances of the test piles are evaluated using the combined load-settlement curve, and compared with the results from the end of initial driving and restrike tests. The results showed that the resistances, which are evaluated using the combined load-settlement curve, may overcome the underestimation of the resistance because of the insufficient driven energy. In addition, the resistance resulted from the combined load-settlement curve may be more similar to that from the static load test because the suggested load transfer curve is closer to the behavior of the embedded pile compared to the results of end of initial driving and restrike tests. Therefore, this study demonstrates that the combined load-settlement curve may be effectively used for the evaluation of the bearing capacity of embedded piles.

A study on improving the bike way in the Urban river Waterfront (도시하천 수변공간 내 자전거도로 개선방안 연구)

  • Seo, Yong-Soo;Dong, Jae-Uk;Cho, Sung-Hak
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.5
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    • pp.481-489
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    • 2017
  • The study area,Cheonan Stream, is an urban river that flows through urban areas in close proximity to densely populated areas and multi-use facilities. The natural river improvement project from 2006 to 2015 improved the quality of life of local residents with the improvement of river function, the restoration of the natural ecosystem and the securement of hydrophilic space. A bike way in the constructed waterside space was built focusing on trails. This study suggests improvements appropriate for insufficient bike way function-related regulations. The problems of ramps, river crossing facilities, stairway facilities, safety facilities, signs, road markings, and parking facilities, etc.have arisen in the utilization situation and citizen consciousness survey. As an improvement, it was suggested that 12% or fewer ramps should be improved, a submerged bridge should be installed at 7 places separated by stepping bridges, and signs and road markings according to bike way-related regulations should be installed and bike parking facilities at Cheonan station and Cheonan bus terminal should be expanded. The bike way in the waterfront of ChoenanCheon(river) will increase the accessibility and utilization rate of short-distance transportation with the institutional expansion of bike use facilities and work organizations and the improvement of facilities in accordance with urban rivers and bike-related regulations. Therefore, it is expected that the development of the living space will be beneficial for the citizens due to the elimination of traffic in the city and the activation of bike traffic.

A Study on Development of Evaluation Indicator for Golf Course User's Preference (골프장 이용자 선호도 평가지표 개발)

  • Seok, Young-Han;Moon, Seok-Ki;Lee, Eun-Yeob
    • Journal of the Korean Institute of Landscape Architecture
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    • v.38 no.4
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    • pp.25-34
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    • 2010
  • This study was conducted to develop evaluation indicators to improve athletic performance and operational management of golf courses and the results of the research are as follows. Through theoretical research and a preliminary professional survey, 15 on-going evaluations of golf course composition and operational management and 55 sub-evaluation indices were rejected while 10 on-going evaluations and 52 sub-evaluation indicators were reconfigured as final for environmental-friendliness, level of member services, level of human service of game personnel, difficulties of course, management level of the course, fairness of operational management, accessibility and location characteristic, traditions and ambiance of the golf club, quality of course, and course layout. When analyzing the important decision factors in golf course user preference evaluation indicators, the following contributed in the order of higher to lower contributions: the management level of the course, excellence of the course, level of human services for personnel, course layout and environmental-friendliness. When identifying the path coefficient of golf course evaluation indicators, the curvature of a hole and the length of the course had a causal effect on the 'course layout' section. Tournament facilities and various shot values had a causal relationship with 'excellence of the course', in the order of higher to lower, and convenience of waiting and fair allocation of reservations for 'fairness of operational management'. The history of the golf course and its environmental characteristics, history and culture of the region have relatively higher causal effects on 'traditions of the golf club' and geographical conditions on 'accessibility and location characteristics', pesticide and fertilizer usage and water pollution on 'environmental-friendliness', and member benefit and kindness of employees on 'level of member services'. The kindness and expertise of the game personnel had a relatively higher causal effect on the 'level of human services of game personnel', the location of tenning area, and location of OB and hazards on 'difficulties of course', and rough conditions and obstacles management on 'management level of the course'. There is a need to complete a systematic evaluation index system for golf course user preferences through future studies for a more detailed assessment, as well as a process to verify these evaluation indicators by application to domestic and international golf courses.

Major Risk Factors to Implement CM at Risk Pilot Project on the Public Sector (시공책임형 CM 발주방식 공공부문 시범사업 사례를 통한 리스크 도출)

  • Han, Jonghoon;Kim, Kyungtae;Ahn, Yonghan
    • Korean Journal of Construction Engineering and Management
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    • v.19 no.3
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    • pp.61-69
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    • 2018
  • The buildings are getting enormous and more complex as well as the requirement of the owner which wants diverse and efficient. Moreover advanced management is necessary for construction services and a new method of delivering project is now required. In order to expand the delivering method and the construction industry, we have to introduced the CM at Risk method. However, despite the fact that six years have passed already the CM at Risk regulation was introduced, the contract amount in significantly lower than that of the CM for fee, and also there is no CM at Risk project in the public sector. As a result, three pilot projects are currently underway for the LH(Korea Land & Housing Corporation) in order to set up a CM at Risk for the public sector. However, detailed regulations related to CM at Risk have not yet been implemented in Korea. Therefore, in this study, I am trying to understand the risks that could incur when practitioners participate in the three pilot projects that are currently underway and employed in the public sector wherein the CM at Risk is normally introduced. Based on the results of this study, It will be able to utilize as a basic data for future CM at Risk delivery system improvement and enactment.

The Change of Riverside Vegetation by Construction of Ecological Stream in Suwoncheon, Gyeonggi Province (경기도 수원천 생태하천 복원사업 이후 식생변화 연구)

  • Choe, Il-Hong;Han, Bong-Ho;Ki, Kyong-Seok
    • Korean Journal of Environment and Ecology
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    • v.24 no.6
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    • pp.723-734
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    • 2010
  • This study aims to analyze the change in vegetation for 10 years after the construction, targeting Suwoncheon, the first domestic ecological stream construction project. As for the section for the study, the section from Gyeonggi bridge to Youngyeon bridge, the first restoration project section, was targeted. The research districts consisted of 3 districts depending on topographical structure. Investigation check cosisted of cross-sectional topographical structure, vegetation status and the structure of herbaceous plant community. As for the cross-sectional topographical structure of the stream, the width of entire stream was 26.5~28.0m and water channel is 10~20m. The area for hydrophilic space was securing spacious riverside. Upper stream of reservoir beam was shallow and slow in reservoir area above weir. Lower stream of reservoir beam, the width of water channel was narrow and ripples were formed. Among species, 9 plants were planted and 6 species plants including Salix gracilistyla, Phragmites communis and Zoysia japonica were planted at the time of construction. In the water side, there were 2 species, such as Zoysia japonica and Trifolium repens, etc, still remained after seeding at the time of constrcution. The planted plants which were observed through this investigation, were 2 species such as Festuca arundinacea and Dactylis glomerata. Apart from the planted plants, arid climate herbaceous plant such as Setaria viridis and Artemisia princeps var. orientalis formed power and the naturalized species variously emerged in 15 species. For revetment, natural stone stacking method was condicted and Salix gracilistyla, Aceriphyllum rossii, etc were planted. But all the planted plants disappeared and now it was covered with Equisetum arvense and Humulus japonicus. It was because that the base for growth and development of the plants was not constructed at the time of restoration in a way of attaching natural stones onto the concrete base. In the water channel, various wetland species including Typha orientalis, Acorus calamus var. angustatus and Phragmites communis, etc, were planted but only Salix gracilistyla, Phragmites communis and Zizania latifolia remained. As for species of the autochthons, Persicaria thunbergii was dominant. In the lower stream of reservoir beam, Humulus japonicus formed forces. In the hydrophilic space, it was necessary to direct the landscape of in-stream vegetation in cosideration of users. For this, planting Miscanthus sacchariflorus in a community was proposed. In the upper stream of reservoir beam, suplementary screen seeding was necessary so that Zizania latifolia, Typha orientalis and Phragmites communis can fit the depth of water. In the Lower stream of reservoir beam, it was necessary to constantly manage Humulus japonicus so that the wetland autochthons species, such as Phragmites communis and Persicaria thunbergii can establish power more stably.

Determinants of Efficiency of Specialty Construction Companies Using DEA and Tobit Regression Models (DEA와 토빗회귀 모형을 이용한 전문건설기업 효율성 결정요인 분석)

  • Jung, Dae-Woon;Son, Young-Hoon;Kim, Kyung-Rai
    • Korean Journal of Construction Engineering and Management
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    • v.25 no.2
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    • pp.45-55
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    • 2024
  • This study analyzed the efficiency determinants of specialty construction companies by industry using the DEA model and the Tobit model. The analysis targets are 394 specialty construction companies as of 2022. As a result of analysis of efficiency determinants using 12 company characteristics as independent variables, the biggest problem for specialty construction companies was overall efficiency reduction due to rising labor costs. In addition, in a situation where construction companies' loan regulations are severe, the debt ratio was found to have a positive effect on efficiency. Company size had a different impact by industry, and the number of businesses held, credit score, and total capital turnover had an effect only on some industries. This study presents results that are an advance on existing research in that it strategically analyzes factors for improving the efficiency of specialty construction companies. However, it has limitations such as limiting the analysis to only specialty construction companies subject to external audit, insufficient number of companies subject to analysis by industry, and analyzing relative efficiency in the same category for each industry.

Social Innovation and New Roles of Public Institution as a Regional Development Agency: The Preliminary Study with the Case of Urban Development Corporations (사회적 혁신과 지역발전 주체로서 공공기관의 새로운 역할 -광역단위 도시.개발공사 사례를 통한 시론적 검토-)

  • Lee, Wonho
    • Journal of the Economic Geographical Society of Korea
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    • v.16 no.2
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    • pp.310-321
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    • 2013
  • The paper aims to understand the concept of social innovation and its development stages emerging as a new regional development policy trend and to define the role of public sector for social innovation. Spatial policy issues that urban development corporations to carry out development projects for regional policy need to deal with have expanded to include crucial social issues such as poverty, quality of life and happiness. Therefore it is increasingly significant for them to take social innovation into consideration. In this context, this study formulates evaluation framework for the role of public sector in social innovation and investigates its position and limitation in social innovation practices. As a result, almost all corporations have made various efforts for promoting both public purposes of housing and land development and social contribution for the community. However, few corporations have achieved organizational capacity building and idea implementation for social innovation. Growing demand for social innovation in both spatial and regional policies tends to bring up profound challenges to public regional development agencies including urban development corporations. It is then a time to seek to carry out related researches and policy option formulation for social innovation in the near future.

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An Experimental Study on a Performance Evaluation of Internal Insulation of Buildings Over 20 Years Old (20년 이상 경과된 노후건축물의 단열재 성능평가에 관한 실험적 연구)

  • Kim, Hyun-Jin;Choi, Se-Jin
    • Journal of the Korea Institute of Building Construction
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    • v.19 no.6
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    • pp.539-547
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    • 2019
  • Recently, the international community signed a climate change agreement to prevent global warming. Yet currently, the fossil fuels have been widely used in to supply building energy for cooling and heating. The Green Building certification (G-SEED), an energy efficiency rating for new or existing buildings requires that buildings meet certain conditions. Insulation is used as a building material to reduce the energy supply to buildings and to improve the thermal insulation, and it accounts for more than 90% of the total heat resistance provided by the building surface components that meet the energy-saving design standards of new buildings. In this investigation, a performance evaluation study was conducted through an experimental study by directly extracting the foam polystyrene insulation on-site during the remodeling of a building that was in the range of 22~38 years old. Through tests, it was found that the thermal conductivity of the extrusion method insulation (XPS) was reduced by 48% and the compressive strength of XPS decreased by 36% compared to KS M 3808, which is the initial quality standard. For bead method insulation (EPS) with a thickness of 50mm, the thermal conductivity, the compressive strength, and flexural failure load were similar to the initial quality standard. Therefore, in the calculation of the primary energy requirement per unit area per year, the performance of bead method insulation can be estimated simply by considering the thickness of the insulation, while a correction factor that considers its performance deterioration should be applied when extrusion method insulation is used.