• Journal of the Korean Institute of Gas
• /
• v.27 no.2
• /
• pp.7-15
• /
• 2023

The electric submersible pump (ESP) has been operating in production wells around the world because of its high applicability and operational efficiency among artificial lift techniques. When operating an ESP in a reservoir, variables such as temperature, pressure, gas/oil ratio, and flow rate are factors that affect ESP performance. In particular, free gas in the production fluid is a major factor that reduces the life and operational efficiency of ESP. This study presents the flow loop system which can implement the performance and damage tests of ESP considering field operating conditions to quantitatively analyze the variables that affect ESP performance. The developed apparatus in an integrated system that can diagnose the failure and causes of ESP, and detect leak of tubing by linking ESP and tubing as one system. In this study, the flow conditions for stable operation of ESP were identified through single phase and two phase flow experiments related to evaluation for the performance of ESP. The results provide the basic data to develop the failure prediction and diagnosis program of ESP, and are expected to be used for real-time monitoring for optimal operating conditions and failure diagnosis for ESP operation.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.3 no.1
• /
• pp.24-33
• /
• 1999

For performance prediction and diagnostics of gas turbine engines, linear and non-linear gas path analysis are applied. In order to find optimal instrument parameters to detect the physical faults such as (outing, erosion and corrosion, non-linear gas path analysis is used. A typical industrial gas turbine engine, TB5000, is used to study the effect of physical faults on engine performance. Through comparison of RMS error between linear and non-linear gas path analysis, the optimal instrument parameters can be defined. As a result, it is found that the linear GPA has the level of error introduced by the assumption of the linear mode: can be of the same order of magnitude as the fault being soughtwhile the non-linear GPA can be solved the non-linear relationships between dependent and independent parameters using an iterative method such as the Newton-Raphson method with sufficient accuracy.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.15 no.1
• /
• pp.235-242
• /
• 2011

The control performance in active structural control system can be drastically deteriorated when the modeling errors and the uncertainties existing in the disturbances are disregarded in the designing stage. It can even throw the control system into an unstable phase, resulting in out of control against the seismic excitations. The purpose of the study is to investigate the control effectiveness of a non-linear control system called sliding mode controller(SMC) in cooperation with a Tuned Mass Damper subjected to the three seismic excitations selected from the FFT analysis. Even though the transient performance such as settling time and overshoot were deteriorated, the robustness against the system stability was appeared from SMC when the structural masses and stiffness perturbed within the range of ${\pm}30%$. SMC is a feasible technique for active structural control in cooperation with TMD against seismic disturbances, exhibiting robustness in perturbation of system stiffness and mass as well as uncertainties of the disturbances.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.10 no.2
• /
• pp.67-75
• /
• 2006

Recently sewage facilities mainly consisted of concrete structures are being deteriorated seriously by biodeterioration originated from sulfur-oxidizing bacteria. In this study, to prevent biochemical corrosion of the sewer concrete, antibiotics which prevent growth of sulfur-oxidizing bacteria were developed and antimicrobial performance of it was investigated. After that, to consider applicability of antibiotics to concrete, physical properties of concrete spread with antibiotics were investigated. As a results of the study, it was proved that the antimicrobial performance of antibiotics was available. Also compressive strength and bond strength of concrete didn't closely connected with antibiotics, and resistance to abrasion, water absorption and air permeability of concrete was improved remarkably by spraying with it.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.17 no.4
• /
• pp.66-74
• /
• 2013

In this study, corrosion potential ($E_{corr}$), corrosion rate, and polarization resistance were measured aimed at inorganic inhibitors (passive film type) and organic inhibitors (absorption type). The experiment was conducted using potentiostat for the variable molar ratio and chloride ion concentration of the components of inhibitors in an aqueous solution of saturated calcium hydroxide targeting corrosion. As a result, it was possible to ensure an anticorrosive performance of at least a 1.2 molar ratio of inorganic inhibitors. Also, the organic inhibitors ensured the prevention of the anticorrosive performance of at least about a 0.3 molar ratio. It also showed the tendency that between polarization resistance and corrosion rate, Ecorr and corrosion rate is inversely proportional to the linear. Conversely, the tendency between polarization resistance and Ecorr is proportional to the linear. Also, a distinct difference in organic and inorganic inhibitors' relationship to Ecorr, corrosion rate, and polarization resistance was not shown.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.23 no.4
• /
• pp.120-130
• /
• 2019

In this study, based on the correlation between traffic volume data and vertical displacement data developed in previous research using the bridge maintenance big data of 2006, the vertical displacement estimation model using the traffic volume data of Gwangan Bridge for 10 years A comparison of the performance of the developed model with the current applicability is presented. The present applicability of the developed model is analyzed that the estimated displacement is similar to the actual displacement and that the displacement estimation performance of the model based on the structured regression analysis and the principal component analysis is not significantly different from each other. In conclusion, the vertical displacement estimation model using the traffic volume data developed by this study can be effectively used for the analysis of the behavior according to the traffic load of Gwangan Bridge.

• Smart Media Journal
• /
• v.12 no.10
• /
• pp.71-84
• /
• 2023

Paralichthys olivaceus accounts for a large proportion, accounting for more than half of Korea's aquaculture industry. However, about 25-30% of the total breeding volume throughout the year occurs due to diseases, which has a very bad impact on the economic feasibility of fish farms. For the economic growth of Paralichthys olivaceus farms, it is necessary to quickly and accurately diagnose disease symptoms by automating the diagnosis of Paralichthys olivaceus diseases. In this study, we create training data using innovative data collection methods, refining data algorithms, and techniques for partitioning dataset, and compare the Paralichthys olivaceus disease symptom detection performance of four object detection deep learning models(such as YOLOv8, Swin, Vitdet, MvitV2). The experimental findings indicate that the YOLOv8 model demonstrates superiority in terms of average detection rate (mAP) and Estimated Time of Arrival (ETA). If the performance of the AI model proposed in this study is verified, Paralichthys olivaceus farms can diagnose disease symptoms in real time, and it is expected that the productivity of the farm will be greatly improved by rapid preventive measures according to the diagnosis results.

• 전자공학회논문지 IE
• /
• v.49 no.2
• /
• pp.75-81
• /
• 2012

In this paper, restoration methods were applied to restore analog medicine images with an aged image added and then blurred by noises. To restore the aged image blurred by the blurring function and added by noises, it was applied to the restoration methods which are inverse filtering and wiener filtering which are linear restoration techniques and Lucy-Richardson's algorithm which is nonlinear restoration technique. Moreover, ROC curve, a subjective evaluation method, was applied to evaluate the image quality of the restoration image. The wiener filtering using the ratio of constants acquired better image than the inverse filtering, but both of them couldn't improve ability to make a diagnosis. The restoration image applied to Lucy-Richardson algorithm was the best performance of the applied techniques and its sensitivity and specitivity were improved by 15[%] as much performance as the original aged image.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.22 no.1
• /
• pp.107-120
• /
• 2020

In a performance-based evaluation of structures in use, the current performance is assessed by summing up the weighting of the evaluation indices for each performance. In this study, to suggest a performance-based evaluation technique for NATM tunnels in use, the performance evaluation indices were derived by examining the characteristics and similarities of each index developed from previous study. The weighting of the evaluation indices was derived by calculating the relative importance of each evaluation indices from the AHP analysis. In order to develop a quantitative evaluation model, grading criteria for each performance index was derived through literature review, and performance evaluation tables for road and railway tunnels were presented. In order to verify the significance of the proposed performance evaluation model, the correlation analysis was performed between each evaluation index and the final evaluation result. In the correlation analysis, the survey data measured through precision safety diagnosis in the tunnel in use was applied. It may be said that the proposed evaluation indices, weighting, criteria and evaluation models for tunnels in use can be applied to the performance-based maintenance system of tunnels.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.14 no.6
• /
• pp.1139-1144
• /
• 2019

A calibration system for diagnosing and confirming the performance of precision measuring instruments minimizes the risk of misjudgment of calibration resulted by complying with international standard requirements in order to ensure the reliability of calibration results. This paper uses a proposed calibration system suitability assessment and a guard-band technique through an analysis of uncertainty factors when it is impossible to acquire and operate high-performance equipment at a calibration laboratory, and proposes an optimized test limit output model substituting performance standards. The proposed method provides an optimized test standard to meet the quantitative evaluation criteria of the calibration system and the probability of false acceptance risk required by international standards.