• Wind and Structures
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• 제23권6호
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• pp.595-613
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• 2016

Large amplitude oscillation of steepled main cables usually presents during construction of a long-span bridge. To study this phenomenon, six typical main cables with different cross sections during construction are investigated. Two main foci have been conducted. Firstly, aerodynamic coefficients of a main cable are obtained and compared through simulation and wind tunnel test: (1) to ensure the simulation accuracy, influences of the numerical model's grid size, and the jaggy edges of main cable's cross section on main cable's aerodynamic coefficients are investigated; (2) aerodynamic coefficients of main cables at different wind attack angles are obtained based on the wind tunnel test in which the experimental model is made by rigid plastic using the 3D Printing Technology; (3) then numerical results are compared with wind tunnel test results, and they are in good agreement. Secondly, aerodynamic coefficients of the six main cables at different wind attack angles are obtained through numerical simulation. Then Den Hartog criterion is used to analyze the transverse galloping of main cables during construction. Results show all the six main cables may undergo galloping, which may be an important reason for the large amplitude oscillation of steepled main cables during construction. The flow structures around the main cables indicate that the characteristic of the airflow trajectory over a steepled main cable may play an important role in the galloping generation. Engineers should take some effective measures to control this harmful phenomenon due to the big possibility of the onset of galloping during the construction period.

• 한국건설관리학회:학술대회논문집
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• 한국건설관리학회 2007년도 정기학술발표대회 논문집
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• pp.844-847
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• 2007

전 세계적으로 환경에 대한 관심이 고조되는 가운데 각 산업에서의 환경보호를 위한 노력이 꾸준히 진행되고 있다. 건설분야에서도 환경보존 을 노력이 지속되고 있는 실정이다. 이에 본 논문에서는 친환경성, 고내구성, 가변성, 갱신성능 그리고 쾌적성 등의 종합적인 성능을 갖춤으로써 미래형 건축물의 기본요소가 될 수 있는 친환경 지능형 건축 Component system 제안을 위한 요소기술 분석에 초점을 맞추었다. 친환경 지능형 건축 Component system 개발을 위해 요구되는 성능을 파악한 후 그 성능을 구현시키기 위한 요소기술을 분석한 결과, SI주택과 Home Automation 기술이 주요 요소기술로 도출되었다. 그리고 이론 및 문헌 고찰을 통해 도출된 요소기술의 개념 및 개발동향에 대하여 대해 살펴본 후 최종적으로 이러한 기술요소의 융합을 통한 친환경 지능형 건축 Component system 을 제안하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제16권5호
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• pp.1611-1633
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• 2022

At EUROCRYPT 2019, a new block cipher algorithm called BISON was proposed by Canteaut et al. which uses a novel structure named as Whitened Swap-Or-Not (WSN). Unlike the traditional wide trail strategy, the differential and linear properties of this algorithm can be easily determined. However, the encryption speed of the BISON algorithm is quite low due to a large number of iterative rounds needed to ensure certain security margins. Commonly, denoting by n is the data block length, this design requires 3n encryption rounds. Moreover, the block size n of BISON is always odd, which is not convenient for operations performed on a byte level. In order to overcome these issues, we propose a new block cipher, named DBISON, which more efficiently employs the ideas of double layers typical to the BISON-like construction. More precisely, DBISON divides the input into two parts of size n/2 bits and performs the round computations in parallel, which leads to an increased encryption speed. In particular, the data block length n of DBISON can be even, which gives certain additional implementation benefits over BISON. Furthermore, the resistance of DBISON against differential and linear attacks is also investigated. It is shown the maximal differential probability (MDP) is 1/2^n-1 for n encryption rounds and that the maximal linear probability (MLP) is strictly less than 1/2^n-1 when (n/2+3) iterative encryption rounds are used. These estimates are very close to the ideal values when n is close to 256.

• Wind and Structures
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• 제37권6호
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• pp.399-412
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• 2023

Previous studies have shown that the integrated transfer function (ITF) is independent of turbulence characteristics and can be effectively applied to predict the buffeting response of elongated structures, assuming that the strip hypothesis is valid. However, existing research has not effectively identified the ITF through segment model vibration tests, and the influence of the 3D effect on the accuracy of the strip hypothesis and the characteristics of the ITF in wind tunnel tests has not been quantitatively studied. A segment model vibration measurement device that can change a test model's span-width ratio was designed in this study. An airfoil section and a streamlined box girder section structure were taken as the background, and their ITFs were effectively identified under different L/B (L denotes the turbulent integral scale and B denotes the structural width) and model span-width ratios. The influence laws of the 3D effect on the accuracy of the strip hypothesis and ITF identification in wind tunnel tests were systematically investigated. The results showed that L/B and the structural span-width ratio are two significant controlling factors that affect the accuracy of the strip hypothesis and ITF identification. The research provides an effective experimental method for accurately predicting the buffeting response of elongated structures based on ITFs identified through segment model vibration tests.

• Structural Engineering and Mechanics
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• 제69권1호
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• pp.1-10
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• 2019

In the construction of flat plate slabs, which are widely used for tall buildings but have relatively low flexural stiffness, serviceability problems such as excessive deflections and cracks are of great concern. To prevent excessive deflections at service load levels, current design codes require the minimum slab thickness, but the requirement could be unconservative because it is independent on loading and elastic modulus of concrete, both of which have significant effects on slab deflections. In the present study, to investigate the effects of the construction load of shored slabs, reduced flexural stiffness and moment distribution of early-age slabs, and creep and shrinkage of concrete on immediate and time-dependent deflections, numerical analysis was performed using the previously developed numerical models. A parametric study was performed for various design and construction conditions of practical ranges, and a new minimum permissible thickness of flat plate slabs was proposed satisfying the serviceability requirement for deflection. The proposed minimum slab thickness was compared with current design code provisions and numerical analysis results, and it agreed well with the numerical analysis results.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2012년도 춘계 학술논문 발표대회
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• pp.25-27
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• 2012

The domestic construction industry recognize that review of design and construct-ability has the devastating effects. The way to take advantage of BIM for increase the possibility of discovered the design errors in advance are being discussed a lot recently. Since 2012, Public procurement published that the Turn-key project which is the more than 50 billion won in construction have to let the BIM-based design be mandatory. However, people expected the advent of BIM technology can resolve the existing design errors. But the situation is the connection of design stage and construction stage is very insufficient in domestic. Therefore, in this study understanding the types of design errors in construction phase. according the review of design errors before construction. Then can acceleration the application of BIM to improve the workability in a construction site.

• 한국안전학회지
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• 제29권2호
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• pp.38-44
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• 2014

When a cable-stayed bridge is under construction, the cable tension that changes according to the construction phase is the index indicating the proper construction management. In this study, the vibration method using the least-square estimation has been implemented to monitor changing tensions of two multi-strand cables of a cable-stayed bridge under construction. The test bridge is Hwamyung Bridge in Korea with a prestressed concrete box girder. The field tests are executed during the second tensioning stage just after the installation of the key segment. The tensions of two cables are measured before and after the tensioning and 5 days later (i.e., after finishing the tensioning of all cables). The accuracy of the estimated tensions by the vibration method has been improved by employing proper effective lengths of the cables. The measured tensions are compared with the result of the lift-off tests and design tensions. The vibration method shows very good performance in monitoring the changing tensions according to the construction phase with minimal error.

• 한국응용과학기술학회지
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• 제28권4호
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• pp.418-430
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• 2011

This study was conducted to provide an improving direction of K-EIP(Korean Eco-Industrial Park) construction project by company's voluntary participation. For this purpose, we investigated and analyzed the status of domestic eco-industrial park projects from various literatures, foreign EIP cases and FGI(Focus Group Interview). The key issues to construct a voluntary K-EIP are the lack of experts, the difficulties of commercialization financing, and so on. In this study, therefore, the programs to resolve these problems in K-EIP construction project were suggested at the level of government and corporation.

• Advances in concrete construction
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• 제9권5호
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• pp.459-467
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• 2020

Mechanical and thermal properties of composite sandwich wall panels are affected by changes in their external environment. Humidity and temperature changes induce stress on wall panels and their core connectors. Under the action of ambient temperature, temperature on the outer layer of the wall panel changes greatly, while that on the inner layer only changes slightly. As a result, stress concentration exists at the intersection of the connector and the wall blade. In this paper, temperature field and stress field distribution of UHPC-RW-RC (Ultra-High Performance Concrete - Rock Wool - Reinforced Concrete) wall panel under high temperature-sprinkling and heating-freezing conditions were investigated by using the general finite element software ABAQUS. Additionally, design of the connection between the wall panel and the main structure is proposed. Findings may serve as a scientific reference for design of high performance composite sandwich wall panels.

• Journal of Construction Engineering and Project Management
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• 제2권3호
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• pp.30-39
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• 2012

Design-build (D&B) has been broadly perceived as an effective project delivery method and become popular in the world. However, the implementation process of this innovative procurement method in Vietnam encounters difficulties due mainly to unfamiliarity and inexperience with the approach. Critical success factors (CSFs) which could be used to enhance the project execution are useful to practitioners in Vietnam if identified. A questionnaire survey was employed to identify CSFs of D&B projects in Vietnam. Parties' competence, especially financial capability, and contract documentation are the most important factors significantly affecting project success. It was also shown that the perspectives of two principal parties in D&B projects on the CSFs are statistically correlated. The identified CSFs were then validated with some various D&B projects. The execution results of CSFs' were compared with the projects' performance measured try key performance indicators (KPIs). The most important success factors of this study were also compared with other countries'. The validation and comparison results provide project participants with some useful information to perform D&B projects better. Practitioners should well perform the identified CSFs to enhance the chance of the success of D&B projects in Vietnam. The findings of this study are useful not only to Vietnamese practitioners but also to others who are concerned about D&B method and plan to employ it in Vietnam in future.