• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.867-872
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• 2020

Oil storage tanks are a major structure in chemical industrial complexes. Damage to the structure due to natural disasters or poor management can cause additional damage, such as leakage of chemicals, fire, and explosion, so it is essential to understand the deformation. In this study, data on oil storage tanks were acquired using a 3D laser scanner, and various analyzes were performed for storage tank management by comparing them with design data. Modeling of the oil storage tank was performed using the data and design drawings acquired by a 3D laser scanner. An inspection of the oil storage tank was effectively performed by overlapping. In addition, cross-sectional and exploded views of the deformation were produced to generate visible data on the deformation of the facility, and it was suggested that the oil storage tank had a maximum deformation of -7.16mm through quantitative analysis. Data that can be used for additional work was obtained by producing drawings to be precisely inspected for areas with large deformation. In the future, an inspection of oil storage tanks using 3D laser scanners is quantitative and visible data on oil storage tank deformation. This will greatly improve the efficiency of facility management by rebuilding it.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.6
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• pp.206-216
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• 2020

As the number of aging railway bridges in Korea increases, maintenance costs due to aging are increasing and continuous management is becoming more important. However, while the number of old facilities to be managed increases, there is a shortage of professional personnel capable of inspecting and diagnosing these old facilities. To solve these problems, this study presents an improved model that can detect Local damage to structures using machine learning techniques of AI technology. To construct a damage detection machine learning model, an analysis model of the bridge was set by referring to the design drawing of a non-ballasted plate-girder railroad bridge. Static strain data according to the damage scenario was extracted with the analysis model, and the Local damage index based on the reliability of the bridge was presented using statistical techniques. Damage was performed in a three-step process of identifying the damage existence, the damage location, and the damage severity. In the estimation of the damage severity, a linear regression model was additionally considered to detect random damage. Finally, the random damage location was estimated and verified using a machine learning-based damage detection classification learning model and a regression model.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.4D
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• pp.397-406
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• 2012

Contributed acceptance system is causing problems with the usefulness and follow-up services and the like, other than the origin purpose which needs to be operated as rational adjustment method between the public interest and the private. Accordingly, this study has examine the problems by analyzing the present condition of practical public facilities and has the purpose on drawing the improvements by conducting consciousness survey from in substance users. The problems drawn from the analysis and the survey are location and position of the public facilities by reason of making public facilities at leftover land, the awareness and use as in-site facilities, creating street facilities without considering the use and safety of the users, follow-up service issues and the usefulness issues by creation without considering the surrounding conditions. The proposal of improvements for efficient operation by each problems are devising plans by considering location and position of the facilities for utilization and usefulness, secondly the necessity of the public relations for the improvements of the utilization of public facilities. thirdly, conducting the legal obligation by installing direction boards for its awareness of public facilities and delegating operation of facilities to public corporations such as SH, LH and inhabitants for efficient follow-up services, lastly, establishing the public facility map service which could figure out the surrounding conditions of public facilities to utilize for the contributed acceptance.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.5A
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• pp.351-360
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• 2011

Jacket-type offshore structures are always exposed to severe environmental conditions such as salt, high speed of current, wave, and wind compared with other onshore structures. In spite of the importance of maintaining the structural integrity for offshore structure, there are few cases to apply structural health monitoring (SHM) system in practice. The impedance-based SHM is a kind of local SHM techniques and to date, numerous techniques and algorithms have been proposed for local SHM of real-scale structures. However, it still requires a significant challenge for practical applications to compensate unknown environmental effects and to extract only damage features from impedance signals. In this study, the impedance-based SHM was carried out on a 1/20-scaled model of an Uldolmok current power plant structure under changes in temperature and transverse loadings. Principal component analysis (PCA) was applied using conventional damage index to eliminate principal components sensitive to environmental change. It was found that the proposed PCA-base approach is an effective tool for long-term SHM under significant environmental changes.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.6
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• pp.903-911
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• 2019

The multi-utility tunnel is one of the essential social infrastructures, but it is difficult to establish the multi-utility tunnel due to the scale of the National Land Planning and Utilization Act (2 million square meters). In this paper, we analyze the feasibility of establishing the multi-utility tunnel in the existing city in order to activate the multi-utility tunnel installation. For the feasibility analysis, the scale was classified into four categories based on related laws, and related indicators were selected and evaluated using feasibility and economic analysis. Three kinds/four kinds of suitable multi-utility tunnel for the scale of the existing city were shown, and five kinds of multi-utility tunnel were considered suitable for the new city over 2 million square meters. The results of the overall score evaluation of the tunnel type of the existing city and the open type of the new city of 2 million square meters or more, which is the obligation to install the multi-utility tunnel, do not show much difference and suggest the validity of the installation of the multi-utility tunnel in various scale of the existing city.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.6
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• pp.877-886
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• 2019

The size of the subway entrance should be calculated according to the user's demand, but Korea has the same size for each entrance by applying a uniform value. Recently, the installation of mobile convenience facilities such as escalators, elevators, etc. is mandated by the traffic weakness promotion law, but it is inconvenient to use the existing stations because it is mainly arranged in the place where it can be installed regardless of user demand. This study aims to establish a model for estimating the size of mobile convenience facilities by predicting the use demand of each station entrance so that the location and size of mobile facilities can be reflected in the design or construction of the station. To this end, a multiple regression model was established to forecast daily demand by utilizing the demand for getting on and off by station and the building association area for each purpose around the railway station. The actual data of Dongdaemun and Jonggak Stations were used to verify the estimated model. In addition, the escalator installation scale was compared / analyzed by doorway using domestic and overseas escalator equations. As a result, it was more accurate to estimate the usage demand for a single station. Also, Jonggak Station has an up and down escalator installed at exit 1, but it was analyzed that it is appropriate to install at exit 4. This study is an advanced form of the essay model for estimating the users of the entrance and exit users of urban railway stations published in 2018. In addition, it seems to be the basis of the current escalator installation criteria.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.6
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• pp.1277-1285
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• 2015

It has been known that the conventional retaining wall system with timber lagging and H pile has several problems such as the irregular gap between H-piles, cutting or adding to standard timber, back fill over first step excavation, and especially break-down accident at the disjoint of wall system. In the practical excavation, these problems may lead to worker's accident and the inefficiency of construction economy. To solve the above problems, a new method using prefabricated retaining wall was proposed and verified. The characteristics of the new method is to replace timber wall as free-sliding steel-lagging and connector. To check its verification and application, laboratory tests such as bending strength, tensile strength, and fatigue strength were carried out. Also, a pilot test in the field and numerical simulations under various ground conditions were performed. From the researches, it is found that the prefabricated retaining wall plate can be superior to the conventional timber lagging plate in the strength. It is also found that the proposed methods can be effective in the reuse of retaining wall plate and safe in the disjoint of wall system. Finally, it is desired that the proposed method will be effective in the reduction of the imported timbers and helpful in the safety of retaining wall construction.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.5
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• pp.1797-1807
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• 2013

Dams always have the possibility of failure due to unexpected natural phenomena. In particular, dam failure can cause huge damage including damage for humans and properties when dam downstream regions are densely populated or have important national facilities. Although many studies have been conducted on the analysis of flood waves about single dam failure thus far, studies on the analysis of flood waves about the sequential failure of dams are lacking. Therefore, the purpose of this study was to calculate the peak discharge of sequential failure of dams through flood wave analysis of sequential failure of dams and this analysis techniques to predict flood wave propagation situation in downstream regions. To this end, failure flood wave analysis were conducted for Lawn Lake Dam which is a case of sequential failure of dams among actual failure cases using DAMBRK to test the suitability of the dam failure flood wave analysis model. Based on the results, flood wave analysis of sequential failure of dams were conducted for A dam in Korea assuming a virtual extreme flood to predict flood wave propagation situations and 2-dimensional flood wave analysis were conducted for major flooding points. Then, the 1, 2-dimensional flood wave analysis were compared and analyzed. The results showed goodness-of-fit values exceeding 90% and thus the accuracy of the 1-dimensional sequential failure of dams simulation could be identified. The results of this study are considered to be able to contribute to the provision of basic data for the establishment of disaster prevention measures for rivers related to sequential failure of dams.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.5 no.2
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• pp.109-120
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• 1985

This thesis is a study on multiple close range photogrammetry, and the purpose of this study is to develop the most accurate adjustment method of three dimensional object coordinates. This was achieved by comparing the standard errors of actual data to the computed values from 2 photos and multiple photos. The conventional methods for multiple photos have been analyzed by using geometric model formation. But in this study, the equation of collinearity condition which has been applied to aerial photogrammetry was derived to be a basic principle of close range photogrammetry, and the algorithm for analyzing multiple photos was developed using simultaneous bundle adjustment. The method used in this study, showed more homogeneous accuracy in coordinate and more consistent variance of error than those of conventional methods. It was found that the cases using 3, 4, and 5 photos were more accurate than using 2 photos; the accuracies were improved to 15%, 35%, and 50%, for each case. Thus this study is expected to be useful in measuring the geometry of historic monuments and other structures requiring high accuracy. Also the combined case of multiple photos is considered to be effective for the precise analysis of the objects which are difficult to measure for obstacles.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.3
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• pp.629-636
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• 2017

Urban railway are the most widely used means of transportation in the metropolitan area. It is difficult to draw out problems through the quantitative analysis technique because most of the research results show that most of the guide signs are installed with many or few guide signs. In this study, we propose a method to evaluate the information load and proper installation location at the main decision point in the transfer passageway for Suseo Station by applying Positive Guidance. As a result of analyzing the information load using this technique, it is suggested that the necessary information should be provided centered on the copper node because it provides confusion of the users by providing the same information in the transfer line. It is necessary to obtain guidance on how to remove the sign (advertising, high ceilings, etc). The study will be regarded as a key for the basis and placement of the guidelines for determining the appropriateness of the in the future urban railway station sign guide.