• International Journal of Highway Engineering
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• v.12 no.3
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• pp.27-35
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• 2010

Asphalt Plug Joint(APJ) is an buried expansion joint that enabling the smooth connection of expansion gap and road pavement by filling the gap with bituminous mixture of 20% bitumen and 80% aggregate by weight, so it secures evenness and expansion or contraction using the material's properties. Although APJ is designed to have a 6-7 year lifecycle, there are some cases where it is damaged within the first six months. This early damage cause traffic congestion due to frequent repair works, and social cost exceeding the installation cost of the joint. So, in this research, we have developed a new system of Buried Folding Lattice Joint(BFLJ) which can overcome the disadvantages of APJ, and have analyzed and compared it's performance with the conventional APJ through experiment with specimens. As a result of the experiment, APJ had crack formation on both ends of the gap plate, spreading to the surface of the expansion joint. With this result, we can conclude that the reason for early damage is the tension failure due to the concentration of strain in the asphalt mixture along the end of gap plate and the debonding along the joint section. In contrast, the newly developed BFLJ induced even transformation in the joint by applying moving stud and high performance material, and resolved APJ's disadvantage of strain concentration. Therefore, it could be seen that the newly developed BFLJ could overcome the disadvantages of APJ and prevent early damage.

• Journal of Korean Society of Steel Construction
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• v.20 no.4
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• pp.483-491
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• 2008

There has been much focus on the strong axis steel moment connections after the Northridge earthquake in 1994. However, research studieson the seismic behavior of weak axis moment connections could be hardly found despite the fact that these connection details have been frequently used as seismic details of MRF in Korea. Therefore, the objective of this research is to provide better knowledge on the seismic behavior of weak-axis steel moment connections, which can be widely applicable to many structures with similar characteristics. For this purpose, an experimental program was designed and performed with twotypes of weak-axis steel moment connections, namely the bracket type and WUF-B type, based on the survey of existing field data and literatures. Using the experimental results obtained from the quasi-static cyclic testing of these specimens, structural performances of the joints such as hysteretic curves, maximum strength capacities and the strain of reinforced bars were investigated. From the test results, the bracket-type connection was shown to have more than a 5% story drift capacity, compared with the WUF-B type connection's 4%. These specimens were also shown to have higher strength capacities than the nominal design strength. The bracket-type connection showed a slow strength degradation after maximum strength was researched. However,the WUF-B type connection showed a rapid strength degradation that caused brittle behavior.

• Journal of the Korean GEO-environmental Society
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• v.18 no.9
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• pp.19-31
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• 2017

In case of USA, the drilled shaft and the driven pile in the field showed a good correlation in the analysis of the bearing capacity between the dynamic load test and the static load test. However, in Korea, we mainly install the bored pile, which is not widely used overseas and we tried to confirm the reliability of the dynamic load test on the bored pile, because many people questioned the reliability of it. In this study, load tests were carried out on PHC bored piles in LH field (Cheonan, Incheon, Uijeongbu), and the bearing capacity of the dynamic load test (EOID 7times, Restrike 7times) and the static load test (7times) were compared and analyzed. As a result, the average of the bearing capacity of the static load test was 27% higher than that of the dynamic load test (reliability : 0.73, coefficient of variation : 0.3). And the average of the bearing capacity of the static load test (Davisson) was 27% higher than that of the bearing capacity of the dynamic load test (Davisson) (reliability : 0.73, coefficient of variation : 0.2). To reduce the difference between the bearing capacity of the dynamic load test and the static load test, we proposed modified bearing capacity of dynamic load test (base bearing capacity of EOID + skin frictional force of restrike) and difference between the bearing capacities was reduced to 9% (reliability : 0.91, coefficient of variation : 0.2). And the coefficient of variation was reduced to 0.2 and the consistency of analysis increased.

• Korean Journal of Construction Engineering and Management
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• v.22 no.5
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• pp.86-98
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• 2021

In this study, we developed a simulation model for supply chain management of Precast Concrete (PC) based construction. To this end, information on the Factory Production/Site Construction system was collected through literature review and field research, and based on this information, a simulation model was defined by describing the supply chain, entities, resources, and processes. Next, using the Arena simulation software, a simulation model for the PC supply chain was developed by setting model frameworks, data modules, flowchart modules, and animation modules. Finally, verification and validation were performed using five review methodologies such as model check, animation check, extreme value test, average value test, and actual case test to the developed model. As a result, it was found that the model adequately represented the flows and characteristics of the PC supply chain without any logical errors and provided accurate performance evaluation values for the target supply chains. It is expected that the proposed simulation model will faithfully play a role as a performance evaluation platform in the future for developing management techniques in order to optimally operate the PC supply chain.

• Journal of the Korean Geotechnical Society
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• v.35 no.8
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• pp.31-42
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• 2019

A total of 73 pile design data for prebored PHC piles was analyzed to study the current design method. Based on the design data, a ratio of skin friction to total capacity from the pile design data was about 20~53%. Such low ratio of skin friction to total capacity tends to underestimate skin friction. Considering this tendency, the current design method should be improved. Also, an average design efficiency of PHC pile capacity was 70% and an average design efficiency for bearing capacity of soil or weathered rock was 80%, which shows slightly higher value than the former. This is probably due to the fact that the allowable bearing capacity is estimated to be equal to or slightly higher than the design load. Hence, the allowable bearing capacity should be estimated to be higher than the long-term allowable compressive force of the PHC pile. In the current design method, skin friction is calculated to be about 2.2 times lower than end bearing. The current design method for prebored PHC piles applied foreign design methods without any verification of applicability to the domestic soil or rock condition. Therefore, the current design method for prebored PHC piles should be improved.

• Korean Journal of Construction Engineering and Management
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• v.20 no.1
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• pp.3-13
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• 2019

Recently, quality problems of steel used for construction have been raised as a cause of building collapse and safety accidents. Accordingly, it becomes more important to secure quality through material management, procurement management, and construction management for construction used steels. However, the quality management for construction used steels is confined to technical production and process control. So, it does not provide a solution of various non-conforming steel products issues. Therefore, this study suggests improvements of the construction system to secure quality of the construction used steels. Through expert interviews, we identify the items for system improvement and derive the top priority items by considering utility through a structured Analytic Hierarchy Process (AHP). It also divided the respondents into enterprise and research groups to analyze differences, implications and future improvement issues and suggest a road map. It is expected that the priority items derived in this study could be useful as a basic data for making policy decisions to assure the quality of construction used steel.

• Korea Science and Art Forum
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• v.37 no.3
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• pp.135-145
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• 2019

IFC(Industry Foundation Classes) is used for information exchange in BIM-based collaboration process, and it does not secure reliability of information exchange results between fields due to structural limitations. In the end, it is a realistic problem that we have to use specialized BIM software by field, and we can not secure smooth interoperability in the process of information exchange and change. This study was conducted to find ways to secure the interoperability of BIM work between architecture and structure fields by utilizing Open Source provided by software developers to solve these problems. First, through expert survey and in-depth interview, information and improvement factors required in the process of collaboration between architecture and structure were derived. Second, in order to find a solution to the improvement factors, existing studies related to Open-API and domestic and overseas APIs were investigated and analyzed. Third, Ad-On was developed to secure interoperability by using Open API, mainly BIM S/W, which is mainly used in each field. As a result of the study, the possibility of securing interoperability through the management of the design change history between fields was confirmed by using API. It is judged that the application range of API will be expanded to the construction and maintenance field in the future. Therefore, in order to increase the usability for application diffusion, further research on interface improvement through user-centered verification is needed.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.1
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• pp.33-40
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• 2021

In recent years, many construction projects become large and complicated, and construction accidents also steadily increase, which grows interest in the safety and maintenance during construction. Many of the construction accidents are related to temporary construction and structures, but the safety evaluation and management during construction are unclear and indefinite due to the short operating period and continuous change in the formation of the temporary structure. The system support, which is one of the temporary structures to support the pouring load of concrete, was proposed to easily install and dismantle members with connection parts pre-manufactured. The use of the system support is increasing to improve the safety of the temporary structure during construction. However, the system support, which consists of multiple members, still has uncertainties in connectivity between members and supports of vertical members. Therefore, this study analyzed the structure, load, and accident cases of the system support to define the damage scenarios for member connection, support condition, and lateral displacement. The decrease rate of the critical load was analyzed according to the damage scenarios based on the defined unit structure of the system support. In addition, this study provided vulnerable members for each damage scenario, which could induce instability of the temporary structures during design, construction, and operation of the structure.

• Journal of the Korean Society of Earth Science Education
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• v.14 no.3
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• pp.248-256
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• 2021

The purpose of this study is to investigate the perception of pre-service elementary teachers on the educational approach to metaverse. Questions about metaverse were asked to 71 pre-service elementary teachers who were taking the course 'Study of Textbooks in Elementary Science II'. The results of analyzing the contents of the questions are as follows. The results and conclusions were presented through numerical analysis and static analysis based on the responses to questions presented using the university's LMS system. First, the level of understanding of the metaverse of pre-service elementary teachers is very high. Pre-service elementary teachers, as the MZ generation, are already living in a very fast IT environment that can be the basis of the metaverse, so it would have been helpful to understand the metaverse. Second, the need for the metaverse of pre-service elementary teachers is very high. There was a tendency to think that the perception of pre-service elementary teachers is because the metaverse has many factors that can provide higher quality education beyond the current educational environment. Third, in the question of applicability exploration in the 'Earth and Space' domain of Pre-service elementary teachers, there have been few cases in which instructional design was planned based on instructional design principles. Based on these results, if the possibility of metaverse application is proposed in the 'Earth and Space' domain, educational contents using virtual space that can transcend time and space will be very necessary. Based on these results, suggestions are made as follows. First, educational content incorporating the metaverse technique based on instructional design should be developed and utilized. Second, financial support should be provided so that the metaverse can be implemented in the educational environment. Third, it is necessary to provide training opportunities for teachers (including Pre-service elementary teachers) to give lectures on metaverse.

• Journal of Appropriate Technology
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• v.6 no.2
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• pp.115-125
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• 2020

Housing issues such as mushrooming slums remain as chronic in most developing countries. Due to the state's restrained capacity, the housing-vulnerable's self-help approaches have been increasingly inevitable and vital for addressing the housing issues. However, there are still two challenges: securing good quality with economic efficiency, and climate change mitigation and adaptation. This study aims at doing an architectural experiment by developing and educating the production of eco-friendly interlocking stabilized soil bricks (ISSB) by employing vernacular materials and technologies for housing-vulnerable communities in Indonesia. In collaboration with a local architectural NGO, the study features a co-creation workshop in which 40 evicted households participate in the whole process. Soil analysis, mixed design, compression tests, and economic analysis are carried out. This paper illustrates that ISSB also has a high potential as an alternative to a burned brick or a cement block. The application of ISSB to self-help housing is expected to have socioeconomic and environmental effects, thereby facilitating the housing-vulnerable's self-help approaches and contributing to addressing the housing challenges in Indonesia.