Hydrologic and Physicochemical properties are the properties of water, defined by physicochemical properties such as water temperature, electrical conductivity, pH and the concentration of inorganic ions. Although it is difficult to directly identify the cause of seepage through hydrologic and physicochemical analysis, it can be used as indirect data to estimate the origin of leakage.

In this study, an experimental study of Impulse Thermography was carried out on a concrete specimen with in-placed artificial defects at different depths and dimensions. Then, all the data were processed by Pulse Phase Thermography technique by performing Fast Fourier Transformation. The results were compared with the absolute contrast method.

In Korea, inspection and precise safety diagnosis is regularly carried out to maintain and manage the main tunnel(NATM) which has been passed ten years after completion. In this study, we collected the laboratory test results of the concrete lining in the existing road and railway tunnels, and analyzed the correlation between compressive strength and unit mass of concrete. It is hoped that it will be used for efficient maintenance and management work of tunnels in the future.

Climate change has caused localized torrential rainfalls and typhoons to occur more frequently, increasing damages to both life and property. In particular, debris flows have brought damages not only in mountainous areas but also in urban centers. Many studies have been carried out with the rising concern on debris flows. These studies applied different debris flow models and conduct analyses on behaviors of debris flow and on forecasting. Given this, however, the subject of the impact force of debris flows should also be taken into consideration. Thus, this study applied RAMMS and FLO-2D, two models for the numerical analysis of debris flows used to analyze impact force. Here, the selected study areas are Umyeonsan Mountain in Seoul and Majeoksan Mountain in Chuncheon, where damages on debris flows were caused by the localized heavy rains in 2011. To identify a debris flow–triggering rainfall, we used and applied rainfalls calculated at different frequencies (30-year, 50-year, 100-year, 200-year). This study calculated and compared impact forces produced by the two models at any point in the study areas. Identifying impact forces based on the comparison of the two models will be useful in selecting materials and equipment appropriate when installing facilities in mountainous regions.

The extent damages of concrete structures due to fire occurrence are evaluated. The evaluation of fire safety is evaluated by using the inspection, non-destruction test, fracture test(concrete SEM analysis, concrete heat analysis, rebar fracture test. The criteria for determining the safety of concrete structures are presented using evaluation results.

This paper presents an image processing technique to detect carbonation region of concrete using a silhouette coefficient. From the test results, it was exhibited that the developed technique provided accurate detection of carbonation region of concrete.

In the case of the port mooring facility, jetties with piles are mainly applied in soft ground conditions. In the three-dimensional modeling for the structural analysis of jetties with piles, the boundary conditions between the pile and the ground are universally applied to the Approximate depth of pile supported method and Elastic subgrade reaction spring method. In this study, p-y curve data for the pile ground condition was generated using the LPILE program, and then the nonlinear spring considering the p-y curve as the pile and ground boundary condition was input and analyzed in the 3D modeling of jetties with piles using the MIDAS civil And the necessity of applying the Nonlinear subgrade reaction spring method by comparison with the result and the analysis result according to the existing analysis method is suggested.

This paper presents the assessment of 7-wire strand monitoring using acoustic emission technique for bridges. 7-wire strand is widely used construction materials to provide additional tensile force to bridges. PSC (PreStressed Concrete) bridge and cable-stayed bridge are representatives for such cases. However, as the bridge aging progresses recently, corrosion problems of strand are emerging. For this reason, various NDT (Non-Destructive Test) methods for cable inspection are being studied and applied to the field. One of the NDT methods, acoustic emission technique, is known as an effective technique to detect cable damage and breakage. In this study, to evaluate the applicability of acoustic emission technique to bridges, acoustic emission signals according to presence or absence of the strand were acquired and analyzed by tensile test. As a result, it is considered that the acoustic emission technique will be able to detect corrosion breakage and signs of rupture.

This study presents the investigation for relationship between local damage and structural performance of the 7-wire strand. This strand is often used additional reinforcement of bridges such as PSC (Prestressed Concrete) bridge and cable-stayed bridge. Stay cables are continuously damaged after completion and corrosion is the main cause of damage. Due to its structural characteristics, it is difficult to quantitatively evaluate the degradation cable damage. Therefore the relationship between local damages on strand and structural performance is experimentally and analytically evaluated in this study. The results can be used for the safety management of the cable supported bridges in the future.

Bridge inspection based unmanned aerial vehicle (UAV) has received considerable attention due to its several advantages such as reliability and safety as well as saving time and cost. An unmanned inspection equipment for bridge inspection is composed of UAV and imaging devices such as RGB cameras and infrared cameras. However, many challenging issues should be solved in order to apply this technology to the field. In this paper, an UAV based crack detection method is investigated. To detect the cracks, the image processing techniques with deep learning algorithm are used. To build the spatial information of aging bridge, 3D point cloud based background model is generated.

There are weaknesses of water-pipe buried at river because of difficulty like to invisible exposure by scour. These weaknesses cause flotation, deformation and damage of pipeline. Therefore, this paper presents the survey instrument applying GNSS that KISTEC has recently introduced. Also, we has verified reliability by discovering exposed water-pipe on field

It is necessary to establish countermeasures to prevent spalling in the tunnel ceiling concrete lining from being linked to lack of lining thickness, leading to additional spalling. We analyzed the effect of thinning between the ceiling part and the lining thickness on the safety of the tunnel and confirmed the structural behavior of the lining based on the measured values after practically reinforcing the inside and filling the inside of the lining.

Domestic facilities are managed in accordance with the "Special Law on the Safety and Maintenance of Facilities", and are managed through periodical inspection and safety diagnosis. In the inspection and diagnosis of such facilities, Comprehensive analysis results from exterior and non-destructive survey, and the five grade of the facility is managed. Most of the non-destructive tests are carried out in consideration of operation. In this paper, the purpose of this study is to investigate the change of compressive strength and the characteristics of the core strength in the ○○ tunnel.

Load test is performed to obtain the data to evaluate load carrying capacity and check static & dynamic characteristics of a structure by estimating the real behavior of bridge due to loading the load. The subject facility in this paper is a bridge located on the spiilway of dam and traffic is relatively less than most brige. Considering the age and operation rules of a dam, however, load test and structure programming analysis were performed to check current conditions for structure under in-depth inspection and the results of that analysis are shown.

In this study, a PTZ(Pan-Tilt-Zoom) system was developed to analyze the behavior characteristics of pipe fittings and joints using the image processing techniques. In the developed PTZ system, two cameras and lenses were installed in a pan-tilt drive to measure the strain and deformation angle of the piping components using one system. In-plane cyclic loading test was conducted to verify the validity of the method to measure the strain and deformation angle using the developed PTZ system.

The present study aims to propose a corrosion detection method using a optical fiber sensor coated with a thin iron film. To evaluate the detection accuracy using the proposed method, 2 typed iron film with thicknesses of 100, 200 nm were used to monitor the reflectivity from corroded iron film via light source injection and the measurement was conducted in air, salt water, mortar packed conditions. As a result, it was found that the thickness of iron film is more sensitive to change in the reflectivity than the variation of exposure conditions

This paper presents the surface-wave based non-destructive evaluation on crack repairing performance in concrete. Concrete specimens with different crack depths and identical compositions were prepared for surface wave transmission experiments. Cracked concrete specimens were perfectly repaired through epoxy injections, and recovery of transmission coefficients and spectral energy were confirmed in process of crack repairing. Additionally, the effectiveness and feasibility of spectral energy based assessment techniques for the evaluation of crack in concrete is also investigated.

In the shaking table test, contact displacement sensors are widely being applied to a structure for measuring the displacement responses, but difficulties may arise depending on the condition of the structure. Moreover, the test uneconomically needs temporary facilities for installing sensors and supplementary equipment for saving the displacement responses of a structure. The contact displacement sensors that are currently becoming popular in the shaking table tests are limited depending on their use environments; thus, the reality is that each equipment appears impractical considering its effectiveness and applicability. Therefore, in this study, to verify an algorithm for measuring the displacement responses of a structure using the vision-based system in the shaking table test, the various tests were conducted.

In this study, the natural frequencies of long-span truss bridges with LRB were analyzed and compared. As a result of the mode analysis, a similar mode shape was shown irrespective of whether LRB was applied or not. The natural frequency analysis using the measurement data, the natural frequencies of the first to third transverse modes could not be analyzed due to the small dynamic response, and the natural frequency of the fourth vertical mode was analyzed to be similar to the mode analysis results. As a result of comparing the natural frequency of the vertical direction mode of 18 truss bridges in the past, the bridge with LRB was analyzed to have smaller natural frequency than the bridge without LBR.

As the frequency and period of earthquakes are increasing compared to the past, interest in the safety of rescue facilities including bridges a lot of. The correlation between the statistical index and the surrounding environment was analyzed by using the seismic acceleration measurement data of the bridge.