• Journal of Navigation and Port Research
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• v.31 no.5 s.121
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• pp.421-426
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• 2007

Recently, the defect maintenance period of the new construction structure was extended from 5 years to 10 years. And according to change of realization on the quality of construction and maintenance, a development of semi-permanent method of construction is required for maintenance of blind parts of underwater structure, such as bridge, dam, harbor, etc. In this study, we proposed a floating type sector dry caisson, which is effective to the maintenance of submerged large structures. These large structures were being maintained incompletely, partly due to unskilled divers and difficult working condition. Considering the easiness of access to the maintenance area and the cost for set up the working structure, especially for the case of structure slabs close to the sea surface and harrow pile span structures, we developed and introduced a sector dry caisson instead of the full caisson structure. By doing this, it is easy to move out the caisson rapidly in emergence case. Therefore, we expect that the floating sector caisson will contribute to reduce working time and improve the quality of underwater work in future days.

• Journal of the Korea Institute of Building Construction
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• v.9 no.6
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• pp.161-168
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• 2009

In an architectural construction, underground construction is a critical path forming a major part of the total construction period and cost, and particularly in big cities, its size has been increasing every year. A basement wall currently constructed in the field needs a large functional work force, and the construction is under progress by the Euroform and Soldier system, which is disadvantageous in terms of the construction period. Therefore, in this research, non-supporting forms which are applicable to the buildings construction were developed, based on the non-supporting forms partly used in some civil engineering works. In addition, the size of a form was assumed and its economical efficiency was compared to that of the Euroform and Soldier system which is used most in construction fields, and the results were analyzed. The study results showed that the construction cost of composite non-supporting forms was higher than that of the Euroform and Soldier system by about 8%, and the construction cost of non-composite non-supporting forms were lower than that of the Euroform and Soldier system by about 9%. However, in the case of composite non-supporting forms, the amount of concrete and reinforcing rods remarkably decreased in structural construction, so it has the effect of an economical cost reduction compared to the construction cost of existing walls by about 35%

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2006.11a
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• pp.123-130
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• 2006

Recently, Korean government promotes BTL(Build-Transfer-Lease) for their public construction project to apply private sector's experience and finance initiatives. Many of public buildings and civil infrastructure projects were planned to be delivered by BTL and it helps to continue public projects under tight budget conditions. Since the characteristics of BTL projects, creative ideas for the project function, performance and its LCC (Life Cycle Cost) become more important than usual public work project. This paper introduces the systematic "VE job Plan" application techniques for BTL project and shows the process. This study shows the application of "VE job Plan" for BTL project to help decision making and value improvement. Also, Project cost was estimated by LCC (Life Cycle Cost) analysis. Technical "FAST diagram"was developed and used to find major functions of the project. So, it helps to improve performance of functions and make creative ideas. FAST diagram also help to find relationships between functions and cost. A case study (Daegu Art Gallery BTL Project) was conducted using proposed "VE job Plan. Study demonstrates how value management helps save money and increase functional performance. Researcher found that project can save cost and improve performance of functions significantly by using appropriate VE analysis process at appropriate time.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.8
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• pp.147-156
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• 2016

This study analyzed the impact of changes in the construction business on construction company insolvency according to their size using the vector error correction model. First, this study applied EDF (Expected Default Frequency), which was calculated by KMV (Kealhofer, McQuown and Vasicek) model, as a variable to indicate the insolvency of construction companies. This study set 30 construction companies listed to KOSPI/KOSDAQ for estimating the EDF by size and construction companies were divided into two groups according to their size. To examine the construction business cycles, the amount of construction orders according to the type-residential, non-residential, and civil work- was used as a variable. The serial data was retrieved from TS2000 established by the Korea Listed Companies Association (KLCA), Statistics Korea. The analysis period was between the second quarter of 2001 and fourth quarter of 2015. As a result of calculating the EDF of construction companies by size, as it is generally known, the large-sized construction companies showed lower levels of insolvency than relatively smaller-sized construction companies. On the other hand, impulse response analysis based on VECM confirmed that the level of insolvency of large-scaled companies is more sensitive to business fluctuations than relatively smaller-sized construction companies, particularly changes in the residential construction market. Hence it is a major factor affecting the changes in insolvency of large-sized construction companies.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.12
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• pp.638-643
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• 2017

The 3D laser scanner operates by measuring the distance from the sensor to the target and operates on the same principle as Electronic Distance Measuring (EDM). Recently, 3D laser scanning technology has been rapidly developed in line with the strongly increasing demand for 3D information acquisition. Therefore, it is now possible to more easily acquire geometric information of various objects existing in real space. In this study, we constructed geospatial information by using new equipment which integrated 3D laser scanner and total station, and we suggest the possibility of using new technology for geospatial information construction by comparing and analyzing with existing methods. In the study result, we demonstrated the efficiency of the geospatial information constructed by integration of 3D laser scanner and total station. The proposed method is expected to shorten the time required for data acquisition compared to the existing method using the existing total station. Furthermore, it is possible to use various methods such as cross section analysis and volume calculation using the acquired data. In the future, spatial information construction by integration of 3D laser scanner and total station will help improve work efficiency in related fields.

• Journal of Energy Engineering
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• v.21 no.2
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• pp.152-157
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• 2012

Due to the global warming and energy exhaustion, energy efficiency improvement of construction is recognized the stream of times. To improve the efficiency of the building, in order to energy saving, passive elements should be applied. Then the first step be supposed that applying the new standards about the insulation boundary. The current insulation boundary standards are not reasonable as well as does not divide the purposes. As a result, energy is being wasted and many civil complaints are also occurred. To improve these problems, applying the insulation boundary need to divide the heating and non-heating and subdivide the purpose of construction. In this study, accurate real heating and air conditioning areas are presented that work on the new insulation boundary of purposes and applicable standards. This proposed, by the real heating and air conditioning areas, insulation boundary of purposes, matching the reasonable capacity and load of equipment, by working on standards by optimal maintenance can be energy saving, to present guidelines that environment improvement of actual residents as well as energy saving be expected.

• Korean Security Journal
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• no.20
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• pp.1-18
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• 2009

Recently the demand for civil protection and security guards shows rapid growth by the social development and improve the quality of life. However the supply and education system have some limitations in spite of the high demand guard-secretary. The main role of secretaries has been to accompany superiors in order to maintain their dignity or trait. However, the secretaries are required to play additional roles of safety managers such as a security manager, a protocol manager, an intelligence manager and a protective driver in order to overcome the domestic and the international safety environment and to elevate the quality of service as a competitive work. Therefore, the purpose of this article is to analyse current situation of curriculum on security guard training at the universities related to this department, and to seek an educational model for this area. For that, the following questions will be examined. First, Do the professional training organizations meet social demand for the body and security guards? Second, What kind of training has to be provide for the body and security guards? and what the qualifications of the trainers? Then, what are the differences in training courses between private organizations and universities? Is there differences in the job placement among the trainers of private organizations and universities? etc.. In summary to meet the social demand common curriculum for the body and security guard will be drawn from the analyses of diverse training organizations with different training courses in contents, training periods, educational value, and social aim. For the scholarly identity to the security and secretary studies is th following on the core curriculum, then the university curriculum is very important for that. It is need to arrange the curriculum that is actually current at College or University for the suggestions on scholarly identity and development of the security and secretary studies.

• Journal of Korea Water Resources Association
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• v.40 no.7
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• pp.503-510
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• 2007

In the area of such a nature-friendly stream improvement, it is not established yet which engineering method is suitable for stream environment, due to lack of technology. Therefore, although nature-friendly stream improvement was done with expensive engineering method, the effect has not been fully confirmed, which results from the absence of overall valuation tool of stream improvement. In this regard, it is necessary to develop and apply comprehensive and diverse valuation methods covering stream functions to the analysis of stream improvement. In this study, we collected data from years' of monitoring on the Gyeongcheon river, which is located in Sunchang-eup, Jeollabuk-do and recently underwent an nature-friendly stream improvement work. Based on the data, we developed a series of valuation methods such as stream naturalness evaluation, life cycle evaluation, amenity evaluation, and economic benefit analysis to consider the environmental function of stream from a comprehensive perspective. Stream naturalness evaluation is a quantitative analysis of how natural a stream is, and includes additional valuation items such as ecosystem and water quality for the purpose of overall valuation, unlike existing research focusing on physical elements and structural characteristics of a stream. We developed a method of stream valuation with life cycle assessment to river reorganization project. Amenity evaluation method was developed as a means to analyze residents' satisfaction with stream improvement through questionnaires. Economic benefit analysis was developed as a means to determine the attributes of environmental water supply, ecosystem, river maintenance, and water quality and predict economic benefits using contingent valuation method (CVM) and multi-attribute utility analysis (MAUA) method in order to analyze economic benefits brought in by stream improvement. It is considered that the four methods developed in this study make possible to conduct an overall and quantitative analysis of stream improvement.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.6
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• pp.83-90
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• 2017

Concrete structure for nuclear power plant is mass concrete structure with large wall depth and easily permits cracking in early age due to hydration heat and drying shrinkage. It always needs cooling water so that usually located near to sea shore. The crack on concrete surface permits rapid chloride intrusion and also causes more rapid corrosion in the steel. In the study, the effect of age and crack width on chloride diffusion is evaluated for the concrete for nuclear power plant with 6000 psi strength. For the work, various crack widths with 0.0~1.4 mm are induced and accelerated diffusion test is performed for concrete with 56 days, 180days, and 365 days. With increasing crack width over 1.0mm, diffusion coefficient is enlarged to 2.7~3.1 times and significant reduction of diffusion is evaluated due to age effect. Furthermore, apparent diffusion coefficient and surface chloride content are evaluated for the concrete with various crack width exposed to atmospheric zone with salt spraying at the age of 180 days. The results are also analyzed with those from accelerated diffusion test.

• Journal of the Korean Geotechnical Society
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• v.34 no.7
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• pp.17-27
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• 2018

Sinkholes have occurred in various places around the world and concerns about public safety have been raised in recent years. Particularly, a ground subsidence may occur due to a variety of conditions when developing underground spaces. Ground subsidence refers to the sinking of the Earth's surface caused by the loss of the soil constituting ground due to a certain artificial cause in the ground. Ground subsidence is induced by artificial causes such as the leakage of water supply/sewage pipes and groundwater disturbance, and it is different from a sinkhole, where the sinking of the Earth's surface is induced by the cavity formed due to the melting of limestone in the ground with limestone bedrock. In recent underground development in the urban areas of Korea, damages to surrounding buildings have frequently led to many difficulties with civil complaints and compensation issues, and the collapse of some buildings has resulted in the loss of lives and property. Accordingly, the central government has legislated the Special Act on Underground Safety Management, which will take effect from January 1, 2018. This law specifies an underground safety management system for securing underground safety, under which underground safety impact assessment is performed for projects involving underground excavation work that exceeds a certain size, and safety inspection is regularly performed for underground facilities and the surrounding ground. In this study, the contents of the special act on underground safety management are reviewed, and the direction of development of underground safety policy for preparing preemptive underground safety management preparation and response system is suggested.