• Advances in concrete construction
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• 제9권1호
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• pp.33-41
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• 2020

In this study, polyethylene glycol (PEG) and polyacrylamide (PAM) have been used as self-curing agents to produce self-curing concrete (SC). Compressive strength, ultrasonic pulse velocity (UPV), bulk electrical resistivity, chloride ion penetrability, water permeability, and main microstructural characteristics were examined under different curing regimes, and compared to those of the control concrete mixture with no self-curing agents. One batch of a control mixture and one batch of a SC mixture were air-cured in the lab to act as non-water-cured samples. The water curing regimes for the control mixture included continuous water curing for 3, 7, and 28 days and periodical moist curing using wetted burlap for 3 and 7 days. Curing regimes for the SC mixtures included 3 days of water curing and periodical moist curing for 3 and 7 days. SC mixtures showed better microstructure development and durability performance than those of the air-cured control mixture. A short water curing period of 3 days significantly improved the performance of the SC mixtures similar to that of the control mixture that was water cured for 28 days. SC concrete represents a step towards sustainable construction due to its lower water demand needed for curing and hence can preserve the limited water resources in many parts of the world.

• 한국수자원학회논문집
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• 제43권4호
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• pp.325-336
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• 2010

본 연구에서는 금강유역의 물이용과 댐의 영향에 의한 하천유황의 변화를 평가하였다. 유황변화의 압력지표로서 하천수 이용률과 담수지수를 분석하였다. 유황의 정량적인 변화 분석을 위하여 유황곡선, 유황계수, 홍수 및 갈수 빈도분석과 유량변동분석법을 적용하였다. 8개 분석 대상지점의 결과는 댐 건설전의 유황과 비교할 때 댐과 물이용의 영향으로 고유량 범위에서는 감소하고, 저유량 범위에서는 증가하고 있음을 구체적인 수치로 확인하였다. 금강유역은 연평균유출량의 24%를 저류할 수 있는 139개의 댐과 저수지에 의해 유황이 조절되고 지표수의 이용률이 36%로서 이들의 지표가 유황변화의 압력요인이 되고 있다.

• 대한지리학회지
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• 제41권2호
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• pp.195-211
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• 2006

무역과 관세에 관한 일반협정의 우루과이 라운드 교섭 하에 통과된 '무역관련 지적재산권에 관한 협정'은 지적재산권을 국제통상 분야에 도입시켰을 뿐만 아니라 지적재산권의 대상을 생물다양성에까지 확장시켰다는 중요성을 가진다. 본 연구는 지리학적 관점 (장소와 스케일의 중요성)이 생물다양성과 지적재산권에 관련된 다양한 이슈들을 분석하는데 있어 얼마나 중요성을 가지며, 환경윤리학, 환경경제학, 정치경제학과 같은 다른 학문분야의 접근방법을 통합하고 보완하는지 고찰하였다. 자연, 인문현상의 지역적 차이와 다양한 스케일을 중요시하는 지리학적 관점은 개별적 이슈들로 인식되고 다루어져 왔던 생물다양성, 지적재산권, 이의 국제 통상기구에의 도입이 어떻게 임의적으로 관련지어줬는지 밝혀내는데 공헌한다.

• 한국구조물진단유지관리공학회 논문집
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• 제21권5호
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• pp.42-48
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• 2017

콘크리트 구조물이 화재 손상을 입을 경우 노출온도 및 지속시간에 따라 구조물의 심각한 성능 저하를 야기하며, 콘크리트의 재료 물성 저하를 수반한다. 화재 손상을 입은 콘크리트 구조물의 재사용여부 및 보수보강 판단을 위해서는 손상 직후 및 재양생 조건에 따른 주요 손상 부위의 면밀한 손상 평가가 필요하다. 본 연구에서는 재양생 조건에 따른 화재 손상을 입은 콘크리트의 재료물성 회복에 관한 실험적 연구를 수행하였다. 화재 손상을 입은 콘크리트 시편을 상대습도 및 재양생 기간을 달리한 재양생 조건을 적용하였으며, 충격공진기법을 도입하여 콘크리트 시편의 화재 손상 전후 및 재양생 이후의 동탄성계수를 측정하여 손상 정도를 평가하였다. 측정된 결과로부터 재양생 조건 중 높은 상대습도 조건에서 지배적으로 재료물성의 회복이 발생하였다. 추가적으로 콘크리트 시편의 동탄성계수 및 인장강도의 직접적인 비교 및 선형회귀분석을 수행하여 재양생 조건에 따른 영향을 분석하였으며, 이를 토대로 높은 습도 조건에서 동탄성계수의 회복이 인장강도에 비해 두드러지게 나타남을 확인하였다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2018년도 춘계 학술논문 발표대회
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• pp.339-340
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• 2018

Contemporary concrete structures make use of underground spaces as parking lots and other comfort facilities for efficiency purposes. As underground environmental conditions are in constant exposure to degradation factors from the environment such as groundwater, hydraulic and soil pressure, structural movement and settlement, structural defects in the form of leakage occur. Current maintenance regulations and regimes are unable to respond to this field, as degradation mechanisms in underground environments are still unclear. In this regard, this study proposes the utilization of integrated information sharing system that can provide various technical information for construction designs to prevent leakages in underground concrete structures.

• 디자인학연구
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• 제19권5호
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• pp.139-150
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• 2006

지난 반세기 한국사회는 3, 4, 5공화국에 걸쳐, 28년간의 독재정권기를 거쳤다. 각기 비민주적인 집권이라는 점에서 정통성의 문제가 제기되었는데, 이에 정권은 효과적인 국민통제를 위해 민족주의를 중심으로 한 문화정책을 펼쳤다. 정권의 이데올로기를 강조하기 위해 수단으로 전통 문화를 주목하고 임의로 선별, 고안해 내었으며, '한국문화정체성', 혹은 '한국성'으로 규정해 나갔다. 미술분야의 작가들은 정권이 규정한 한국성을 중심으로 '한국적' 작품들을 생산해내었는데, 대부분 프로파간다의 역할을 수행하며, 이데올로기를 재생산하는데 많은 역할을 담당했다. 이시기 형성된 '한국적 디자인'도 예외가 아니었으며, 환경디자인, 공공건축, 그래픽 디자인, 공공디자인, 영상 영역에 이르기까지 그 범위가 광범위하게 형성되었다. 한국적 디자인은 각기 공화국 별 문화정책 방향에 발맞추어 내용과 양식을 조금씩 달리하며 발전하여 현대에 이르고 있다.

• Advances in concrete construction
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• 제11권5호
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• pp.367-374
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• 2021

The present study investigated the effect of the combined carbonation and steam curing on the physicochemical properties and CO₂ uptake of the Portland cement concrete. Four different curing regimes were adopted during the initial 10 h of curing to evaluate the potential of carbonation curing as an alternative to conventional steam curing in the precast concrete industry from environmental and practical viewpoints. Four combinations of carbonation and steam curing conditions were applied as curing regimes to the samples at an early age. The test results indicated that the samples treated with the combined carbonation and steam curing exhibited higher early strength development compared to the other samples, signifying that carbonation curing can reduce the production time of precast concrete. Furthermore, the CO₂ uptake capacity of the samples was calculated and found to be as high as 18% with respect to the mass of the paste samples. Hence, the simultaneous utilization of steam and CO₂ for the fabrication of precast concrete members has the potential to make precast concrete greener and more cost-effective.

• International Journal of Concrete Structures and Materials
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• 제10권3호
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• pp.271-295
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• 2016

In this study, an extensive literature review has been conducted on the material characterization of UHPC and its potential for large-scale field applicability. The successful production of ultra-high performance concrete (UHPC) depends on its material ingredients and mixture proportioning, which leads to denser and relatively more homogenous particle packing. A database was compiled from various research and field studies around the world on the mechanical and durability performance of UHPC. It is shown that UHPC provides a viable and long-term solution for improved sustainable construction owing to its ultrahigh strength properties, improved fatigue behavior and very low porosity, leading to excellent resistance against aggressive environments. The literature review revealed that the curing regimes and fiber dosage are the main factors that control the mechanical and durability properties of UHPC. Currently, the applications of UHPC in construction are very limited due to its higher initial cost, lack of contractor experience and the absence of widely accepted design provisions. However, sustained research progress in producing UHPC using locally available materials under normal curing conditions should reduce its material cost. Current challenges regarding the implementation of UHPC in full-scale structures are highlighted. This study strives to assist engineers, consultants, contractors and other construction industry stakeholders to better understand the unique characteristics and capabilities of UHPC, which should demystify this resilient and sustainable construction material.

• Journal of Construction Engineering and Project Management
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• 제9권2호
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• pp.1-24
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• 2019

Poor project performance has been noted as the bane in the construction industry globally. This paper sought to investigate, by way of literature, the performance patterns of construction projects in Kenya since independence (1963-2018). This was informed by reports of undesirable project performance in the industry. This descriptive study used available studies previously done in this subject area. In sum, literature is replete with evidence on a myriad of challenges facing the execution of projects. The study established that generally, the project performance is poor and has assumed a chronic trajectory spanning over five decades. On average, the findings reveal that 35-60% of projects initiated in Kenya face cost overruns while time overrun is most severe with 35-73% projects overrunning their schedule. In addition, the findings problematize the issue of plurality of performance measurement regimes in the construction industry. Here, it was observed that no singular construct exists to objectively measure the various facets that constitute the 'health' of a project. This paper has contributed to the body of knowledge by examining the performance patterns in Kenya for over fifty years while at the same time identifying the bottlenecks inherent in projects execution. Importantly, the conceptual performance efficiency framework derived in the current study presents a paradigm shift in the monitoring and evaluation of projects. To this end, an in-depth analysis is recommended on the interaction of efficiency enablers in the buildup of performance efficiency index (PEI). Similarly, a further inquiry is recommended on the integration and impact of the proposed framework in the management of projects.

• 한국해양공학회지
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• 제22권3호
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• pp.8-17
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• 2008

Wrenching climatic changes due to ecocide and global wanning are producing a natural disaster. Coastal zones have been damaged by typhoons and accompanying storm surges. Severe waves, and destruction of the environment are adding to the severity of coastal disasters. There has been an increased interest in these coastal zone problems, and associated social confusion, after the loss of life and terrible property damage caused by typhoon Maemi. Especially if storm surges coincide with high ticks, the loss of life and property damage due to high waters are even worse. Therefore, it is desirable to accurately forecast not only the timing of storm surges but also the amount water level increase. Such forecasts are very important from the view point of coastal defense. In this study, using a numerical model, storm surge was simulated to examine its fluctuation characteristics for the coastal area behind Masan Bay, Korea. In the numerical model, a moving boundary condition was incorporated to explain wave run-up. Numerically predicted inundation regimes and depths were compared with measurements from a field survey. Comparisons of the numerical results and measured data show a very good correlation. The numerical model adapted in this study is expected to be a useful tool for analysis of storm surges, and for predicting inundation regimes due to coastal flooding by severe water waves.