• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.33 no.6
• /
• pp.2575-2582
• /
• 2013

In the delivery systems for public construction works, design-build methods such as turn-key and alternative have contributed to improving the quality of structures and developing the construction technology. However, it is pointed out that construction based on a design-build method is likely to waste a budget due to its higher contract price than construction based on a design-bid-build method. Other issues such as contract monopoly, bid rigging and deliberation irregularity in design-build. Since there are not much works have been accomplished to comparatively analyze the actual performance and effect based on delivery methods, discussing and judging the performance and effect of each deliver method with limited information could lead to an error. Thus, this study by extensively investigates the actual project cost data, ranging from contract price to the construction cost of the public construction works and comparatively analyzed the characteristics of each delivery method about cost structure and fluctuation trend. This work is expected to assist stake-holders in properly understanding delivery systems for public construction works and promoting their efficient management.

• Journal of the Korea Institute of Building Construction
• /
• v.17 no.5
• /
• pp.429-435
• /
• 2017

The aim of the research is, for normal strength range concrete mixture, to evaluate the fluidity development and robustness of the mixture depending on various water reducers. Although a usage of water reducer has been essential to make a concrete under the current conditions of worsen aggregate quality, selection of appropriate performance of water reducer is significant. Hence, in this research, regarding the normal strength range mortar, three different performance of water reducers were evaluated in aspects of securing fluidity, and robustness, rheological behaviors. Additionally, for the concrete mixture, the fluidity change was evaluated depending on unit water content for each different water reducer, and the water reducing performance with manufacturing cost was compared and analyzed. By the result of this research, it is expected to provide a case of determining appropriate kind of water reducer and to contribute on conditions of securing sufficient fluidity with stable quality and economical advantage.

• Journal of the Korea Institute of Building Construction
• /
• v.12 no.2
• /
• pp.211-219
• /
• 2012

On January 27, 2005, the central government of the Republic of Korea designated Jeju Island as an Island of World Peace based on Article 12 of the Special Act for the Jeju Free International City, and the WHO designated Safe Community Jeju in July, 2007. Whenever an industrial accident occurs on Jeju Island, reports in the media raise the question of whether Jeju is a safe city or not. But due to the characteristics of construction sites in Jeju, it is very difficult to employ workers of a certain level. For the safety of workers, it is also thought that owners should make a decisive investment to introduce an education and reward system in order to improve the consciousness level of workers. This research focuses on first-aid on construction sites. It then surveys the level of construction safety management, and suggests improvements in construction safety control and first-aid.

• Korean Journal of Construction Engineering and Management
• /
• v.8 no.5
• /
• pp.119-131
• /
• 2007

Design build (DB) is a construction project delivery system which has become one of the favored ones and the growth of DB by the public agencies has been steadily increasing. DB can be viewed as an evolutionary project delivery system, since DB project team members collaborate on work with each other, keep seeking cost effective and innovative alternatives that meet the construction needs of the project. Thus DB outperformed others in delivery speed, cost saving, and turnover quality. In Korea, DB projects likewise have steadily increased that it is needed to analyze characteristics of DB delivery system in Korea. For that purpose, this research would offer an analysis of characteristics of DB delivery system in Korea using system dynamics model with investigating the public market trend, comparing DB performance to DBB, and analyzing questionnaire survey.

• Journal of the Korean Geosynthetics Society
• /
• v.13 no.2
• /
• pp.21-29
• /
• 2014

The use of filling material based on cement paste is inefficient at field construction because it needs a lot of the charging mass. In addition, it has environmental problem according to the large amount of cement use because its strength is also larger than criterion. The excavated soil with stabilizer can be used as the filling materials when the bored pile is constructed. Therefore, this paper describes field application of solidified soil for economical efficiency and environment-friendly. The static axial load tests and the load-transfer measurements were performed to examine the axial resistant behavior of the piles. As results, the flowability, segregation and bleeding, and bond strength of filling materials was a good performance than that of the existing cement paste. But the skin friction of pile by PDA was slightly decreased than that of the existing cement paste. However, as pile filling materials, and in terms of economics and environment, the applicability of filling material is considered very effective.

• Journal of the Korea Institute of Building Construction
• /
• v.15 no.2
• /
• pp.153-160
• /
• 2015

The marble powder is a by-product that can be freely collected during the manufacturing process of marble, such as sawing, shaping, and polishing. Disposal of this waste powder is one of the environmental problems worldwide today. Therefore, this study investigated to solve this problem by consuming the waste marble powder in high fluidity concrete, as a pore filler. For this purpose, the waste marble powder was used as a binder replacing 5%, 10%, 15%, and 20% of cement in high fluidity concrete. After mixing, slump flow test, time-to-reach the slump flow of 500mm test, O-lot test and U-box test were conducted with fresh concrete. For the hardened concrete, compressive strength was determined at the age of 28 days. According to the test results, the workability of high fluidity concrete increased with the powder of 15% replacement, and the compressive strength of high fluidity concrete also increased with the same amount of powder.

• Journal of the Korea Institute of Building Construction
• /
• v.18 no.3
• /
• pp.211-218
• /
• 2018

This study examined the reliability and revision necessity of concrete standard specifications based on the comparisons with test data obtained by using domestic artificial lightweight aggregates and the contents specified in different foreign specifications including ACI 211.2, ACI 213, ACI 301, JASS 5 and CEB-FIP. To achieve the continuous particle distribution of domestic fine lightweight aggregates, the partial addition of natural sand with the maximum size of 2.5mm was required. To control the segregation and excessive bleeding in the fresh lightweight concrete, the current limitations on the water-to-binder ratio and unit water content need to be modified using lower values. In particular, a rational mixture proportion approach of lightweight concrete needs to be established for the targeted requirements of initial slump, 28-day compressive strength, air content and dry unit weight. Ultimately, significant revision of the concrete standard specifications is required considering the characteristics of domestic artificial lightweight aggregates.

• Korean Journal of Construction Engineering and Management
• /
• v.5 no.5 s.21
• /
• pp.76-83
• /
• 2004

There is a greater importance for underground work designed and built in the urban areas when it comes to considering the cost-effectiveness and the period of construction commensurate with an increasing trend of skyscrapers. At this stage of underground work, it's extremely necessary to choose a proper earth retaining method. However, a frequent change order during construction happens in Korea where different performers design and construct separately, so there is a great possibility for the change order to affect the aspects of construction cost and period which normally define the outcome of construction work. Therefore, the study has suggested the rational retaining wall method by developing the case-based reasoning model as stool to choose a proper retaining wall method applied at the stage of selecting the earth retaining method. Applying the 'CBR Model' developed in the study to the designing and developing stages of the earth retaining work will contribute to the successful outcomes by decreasing any changes of design from implementing the earth retaining work.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.12 no.4
• /
• pp.285-294
• /
• 2010

As there are increasing number of tunneling works these days, shotcrete is used as primary supports in order to secure the stability of tunnels. The quality of shotcrete has a direct influence on tunnels, because it is a primary support which secures the stability of completed tunnels as well as the stability of tunnels under excavation. Especially in case that ordinary shotcrete is used under weak rock conditions or at water gushing sections, more shotcrete is needed and rebound ratio increases. As a result, it is hard to keep economic feasibility. In addition to it, in subway construction, there are cases of separated excavation and it may have a bad influence on construction period or quality. Therefore, in this study, we are going to evaluate the early strength of powder type accelerator.

• Journal of the Korea Institute of Building Construction
• /
• v.23 no.5
• /
• pp.583-593
• /
• 2023

For a holistic and precise assessment of safety benchmarks within a construction venture, it's paramount to delineate between the intrinsic features of the construction and its real-time, on-site performance metrics. In this study, we delved into genuine accident instances to discern the interplay between these construction attributes and on-ground performance determinants in relation to safety mishaps, employing the binomial logit analytical framework. Our scrutiny underscored that construction expenditure profoundly modulates the likelihood of fatal occurrences. Notably, variables pertinent to on-site safety protocols wielded considerable influence over both fatal mishaps and accidents implicating multiple personnel. These revelations intimate that while ascertaining the safety quotient of a construction initiative, a mere classification and recalibration based on fiscal dimensions can elucidate much. Yet, a comprehensive safety appraisal necessitates transcending quantitative indices, such as frequency of mishaps or casualty rates, to encapsulate the multifaceted interventions and strategies adopted at the construction locale.