• Tunnel and Underground Space
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• v.5 no.4
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• pp.297-307
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• 1995

터널은 긴 선상구조물로서 사정조사결과와 다른 지질조건이 나타날 수 있으므로, 안전하고 합리적인 터널공사를 위해서는 시공중 지질조건에 적합한 지보설계를 실시하는 것이 필수적이다. 이를 위해서는 시공중 터널주변자반에 대한 정량적이고 공학적인 평가가 매우 중요하다. 그러나 시공중 암반을 평가하는 것은 매우 어렵고 조사자의 경험과 지식의 차이에 의해 평가정도가 크게 달라져 그 불합리성이 심화되고 있는 실정으로 터널주변암반에 대한 합리적인 평가방법이 절실히 요구되고 있다. 본 연구에서는 터널화상처리, GeoCAD, 역해석으로 구성된 평기시스템을 개발하였다. 본 시스템은 터널막장에서의 조사.시험 및 화상처리기법을 통하여 암반분류.평가를 실시하고, 터널주변 지반구조 및 굴착/지보과정의 3차원 모델링을 통하여 전방지질을 예측가능하게 하며, 터널계측자료의 역해석을 통하여 터널주변 지반의 물성을 정량적으로 평가할 수 있는 체계적이고 종합적인 평가시스템이다. 또한 이를 NATM 공법으로 시공되는 터널현장에 적용하므로써 본 시스템의 현장적용성을 검증하였으며, 이를 통해 적절한 지보공을 시공하여 터널의 안정성을 확보하고 합리적인 시공관리를 달성할 수 있었다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.3A
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• pp.181-188
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• 2009

This study presented the basic data for determining reasonable construction method and evaluating the structural safety of suspension bridges. The analytical program was developed to conduct initial shape and natural frequency analysis, construction stage analysis and reliability analysis considering construction sequences. This program was based on analysis models of suspension bridges and reliability theories used in the previous study. A construction method was established considering various construction variables such as construction order and construction direction of girder and synchronized construction of main and side span etc. The dynamic construction analysis by a construction scheme was conducted with the developed program. Benefits of the characteristic analysis by the construction scheme was presented estimating structural response of critical members respectively. Structural reliability analysis by construction stage was conducted considering aleatory uncertainties. The safety of suspension bridges by established construction method was quantitatively estimated using reliability index and failure probability. Analytical results were re-estimated considering epistemic uncertainties, and critical percentile distributions of risk at the construction stage were presented using the frequency histogram.

• Journal of the Korea Institute of Building Construction
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• v.21 no.1
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• pp.11-19
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• 2021

The aim of the research is providing a fundamental data on quality and constructability of direct tile setting method depending on various cement to sand ratio for tiling dry cement mortar. A large number of tile setting failures reported is related with the cement mortar and its construction for tiling. Because of different materials of tiles, the properties of tiling dry cement mortar, an adhesive for tiling, can influence on quality and constructability of tiling differently. Practically, the easiest way of controlling the properties of the tiling dry cement mortar is to control the proportion of cement and sand. Hence, in this research, sand to cement ratio (S/C) was controlled. Since there is no standarized method on evaluating performance of dry cement mortar for tiling, a several sensory evaluation methods were suggested and executed. According to the experiments conducted in this research, the adhesive performance of cement mortar for tiles can be different depending on the sides such as tile and substrate. Additionally, depending on S/C, finishability, initial adhesive performance, and tile shifting resistance can be changed for ceramic tile. Therefore, under the conditions of this research, about 5 of S/C can be recommended for appropriate performace of tiling dry cement mortar.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.965-968
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• 2008

This study is interested in modeling the selection of optimal repair materials in view of the qualitative evaluation. In order to architecting the evaluation model of various repair alternatives, Analytical hierarchy process techniques was applied to this study. It is composed of aesthetics, easy-to-application, economical efficiency, and environment-friendly properties in upper level. Among the qualitative evaluation items, Environment-friendly properties and execution cost included in economical efficiency is highly weighted. It was concluded that the evaluation model by this study is very useful to choose the best alternative among various repair materials.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.5C
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• pp.187-202
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• 2011

In this Application Study based on the result of the Basic Study, the field test was performed to compare the quality of Ready-mixed shotcrete with that of the existing field mix shotcrete, and the long-term durability was evaluated as tunnel supporting. The plant manufacturing system was also designed to produce standardization materials, and the prototype products were produced with that system. The All-in-one silo mixer was designed and the field construction system using the All-in-one silo mixer was proposed to be most effectively applied Ready-mixed Shotcrete in construction fields. And the application of Ready-mixed Shotcrete was confirmed that more superior to the field mix Shotcrete by evaluating the Constructability and Economics.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.4
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• pp.138-146
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• 2014

Structural safety as well as variety and aesthetics of building facade are currently gathering more attention in building construction and stone curtain wall is widely used in exterior wall. However, two main problems are existed in curtain wall construction method. One is an uniformity of construction quality and the other is a repair work of stone panels. Also, the noise and vibration occurring in construction may be cause of civil complaint. Therefore, a new method is needed to overcome these problems. This paper presents a new stone curtain wall system using under cut anchor and secondary holes that was developed in this study. Additionally, structural performance evaluation was conducted to verify the constructability and structural safety for wind pressure and seismic load. Through the evaluation of this method, improved constructability and economic efficiency were verified.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.4
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• pp.941-951
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• 2015

In the recent years, Korean construction companies have been awarded 680 billion USD in the oversea projects which lead to a successful quantitative growth. However, due to the lack of capability in the core technology and project management compared to the leading companies, in addition to low-price bidding, massive deficit projects have caused problems to the companies. In order to overcome the limitations of the lack of capabilities, the term constructability has been researched recently by developed countries to apply in the practical use. The concept of constructability must be applied for Korean companies to compete in the EPC construction projects. The term constructability is defined as the factor that affect the overall construction process of a project which is defined by the ease of construction and to secure the project quality. Therefore, this study aims to develop a constructability assessment model using the structural equation to assess the factors that affect the constructability in the design and construction stage. The purpose of using the structural equation is to analyze the direct and indirect correlation between each factor that affects the international construction projects. Total of 8 latent variables and 34 measured variables are derived through literature review, corporate reports, experts' interview and surveys. The result of the model suggests the constructability factors that are to be managed the most efficiently to reduce cost, time and improve the quality as well as a countermeasure strategy to successfully execute the target international construction projects.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 1995.03a
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• pp.213-219
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• 1995

터널굴착중 막장조사관찰은 막장의 안전성, 암질판정, 풍화 및 변질정도, 용수상태, 절리의 특성을 파악함으로써 시공의 합리성을 달성할 수 있는 매우 중요한 조사항목이다. 그러나 이러한 작업은 시공상 시간적제약을 받고, 조사자의 경험과 지식의 부족으로 암반에 대한 공학적 평가가 부족한 실정이다. 이러한 문제점을 극복하고, 지반조건변화에 능동적으로 대응한 터널시공을 위해서는 정확한 암반평가가 필수적이라 할 수 있다. (중략)

• Journal of the Korea Institute of Building Construction
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• v.10 no.1
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• pp.181-191
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• 2010

Lightweight panels are currently used in many ways, such as inner walls of the skyscrapers and residential buildings in Korea. Moreover there has been an increasing of interest in developing construction method and quality improvement as many buildings became higher, because there are more advantages like constructability, finishability, and economic efficiency, etc. than previous heavy weight concrete wall. It is necessary to analyze the characteristics and evaluate the performance of lightweight panels when selecting proper methods and materials to building characteristics and builder's demand. However, there doesn't exist systematic data with a classification of lightweight panels' type and performance. The purpose of this study is to classify domestic lightweight panels by both type of exterior board and construction method, and also to evaluate each performance by surveying user's opinion.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.2A
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• pp.93-102
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• 2010

The numerical analysis and safety assessment by construction stages were considered the essential examination particular in order to solving the unstability of long-span bridges in the middle a construction. When estimating structural response characteristics by the construction stage analysis of long-span bridges, the influence of the near-field ground motion (NFGM) would be evaluated as a critical factor for the seismic design because it indicates clearly different aspects from the existing input earthquake motion data. Therefore, this study re-examined the response aspect of long-span bridges considering NFGM characteristics based on the response spectrum result, and advanced the presented numerical analysis program by the related research for conducting the construction stage analysis and reliability assessment of long-span bridges efficiently. The excellency of various construction schemes was assessed using the time history analysis result of critical member considering NFGM characteristics. For evaluating quantitative safety level, the reliability analysis was conducted considering the influence of external uncertainties included in random variables, and presented the safety index and failure probability of the critical construction stage by NFGM characteristics. In addition, the reliability result was examined the influence of internal uncertainties using monte carlo simulation (MCS), and assessed the distribution aspect of the essential analysis result. It is expected that this study will provide the basic information for the construction safety improvement when performing seismic design of long-span bridges considering NFGM characteristics.