• Journal of the Korean GEO-environmental Society
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• v.23 no.12
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• pp.33-39
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• 2022

This paper presents the long-term behavior of tunnel considering the degradation of concrete lining and surrounding soil. Tunnel is a composite structure which has supporting elements (shotcrete, lining, and rockbolt) and surrounding soils. These supporting elements and surrounding soils undergo the degradation as time goes. A proposed degradation function which has two parameters which control the residual strength and degradation shape was applied to the numerical analysis. The results showed the plastic zone was spread around tunnel due to the degradation leading to the increase in unstability of tunnel.

• The Journal of the Convergence on Culture Technology
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• v.9 no.5
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• pp.737-745
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• 2023

This paper discusses a study on developing an artificial intelligence model to detect incidents of fires in distribution switchboard using thermal images. The objective of the research is to preprocess collected thermal images into suitable data for object detection models and design a model capable of determining the occurrence of fires within distribution panels. The study utilizes thermal image data from AI-HUB's industrial complex for training. Two CNN-based deep learning object detection algorithms, namely Faster R-CNN and RetinaNet, are employed to construct models. The paper compares and analyzes these two models, ultimately proposing the optimal model for the task.

• Journal of the Earthquake Engineering Society of Korea
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• v.15 no.5
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• pp.45-54
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• 2011

This paper presents a nonlinear finite element analysis procedure for the performance assessment of deteriorated reinforced concrete bridge columns. A computer program, named RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology), was used to analyze these reinforced concrete structures. Material nonlinearity is taken into account by comprising tensile, compressive and shear models of cracked concrete and a model of reinforcing steel. Advanced deteriorated material models are developed to predict behaviors of deteriorated reinforced concrete bridge columns. The proposed numerical method for the performance of damaged reinforced concrete bridge columns is verified by comparison with reliable experimental results.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.3
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• pp.229-239
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• 2015

In light of the significant increase in the quantities of goods transported and the development of the shipping industry, the frequency of usage of port structures has increased; yet, the government's budget for the shipping & port of SOC has been reduced. Port structures require systematically effective maintenance and management trends that address their growing frequency of usage. In order to construct a productive maintenance system, it is essential to develop deterioration models of port structures that consider various characteristics, such as location, type, use, constructed level, and state of maintenance. Processes for developing such deterioration models include examining factors that cause the structures to deteriorate, collecting data on deteriorating structures, and deciding methods of estimation. The techniques used for developing the deterioration models are multiple regression analysis and Markov chain theory. Multiple regression analysis can reflect changes over time and Markov chain theory can apply status changes based on a probabilistic method. Along with these processes, the deterioration models of open-type and gravity-type wharfs were suggested.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.3
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• pp.6-21
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• 2008

We have investigated the effect of the forward and reverse ESD pulse accumulation on the development of the oxide VCSEL's electrical and optical characteristics. The forward ESD-induced degradation is complicated, showing three degradation phases with increasing ESD voltage while the reverse ESD-induced degradation is divided by a sudden distinctive change in elecorl-optical characteristics. By comparing the measured L-I-V characteristics and their derivatives with the fitted characteristics using an equivalent circuit model as well as the large signal circuit model, the development of the oxide VCSEL's electro-optical characteristics under forward and reverse ESD conditions has been fully understood.

• Journal of the Korea Concrete Institute
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• v.19 no.3
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• pp.359-366
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• 2007

Recently, analysis researches on durability are focused on chloride attack and carbonation due to increased social and engineering significance. Generally, chloride penetration and carbonation occur simultaneously except for in submerged condition and chloride behavior in carbonated concrete is evaluated to be different from that in normal concrete. Furthermore, if unavoidable crack occurs in concrete, it influences not only single attack but also coupled deterioration more severely. This is a study on analysis technique with system dynamics for chloride penetration in concrete structures exposed to coupled chloride attack and carbonation through chloride diffusion, permeation, and carbonation reaction. For the purpose, a modeling for chloride behavior considering diffusion and permeation is performed through previous models for early-aged concrete such as MCHHM (multi component hydration heat model) and MPSFM (micro pore structure formation). Then model for combined deterioration is developed considering changed characteristics such as pore distribution, saturation and dissociation of bound chloride content under carbonation. The developed model is verified through comparison with previous experimental data. Additionally, simulation for combined deterioration in cracked concrete is carried out through utilizing previously developed models for chloride penetration and carbonation in cracked concrete. From the simulated results, CCTZ (chloride-carbonation transition zone) for evaluating combined deterioration is proposed. It is numerically verified that concrete with slag has better resistance to combined deterioration than concrete with OPC in sound and cracked concrete.

• Proceedings of the Korean Reliability Society Conference
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• 2011.06a
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• pp.79-85
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• 2011

LED(Light Emitting Diode) is a powerful device used in applications as diverse as replacements for aviation lighting, automotive lighting as well as in traffic signals. This study is to propose a prediction system based on the degradation model of LED which is determined by combining scale and shape parameter. The degradation model is analysed goodness of fit test using calculated R-square, and is compared with previous models. A LED prediction system using degradation model is developed to automate estimations of degradation parameters and lifetimes.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.12
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• pp.77-83
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• 1998

Generally a moving picture suffers from motion blur, due to relative motion between moving objects and the image formation system. The purpose of this paper is to propose teh model for the motion blur and the restoration method using the regularized iterative technique. In the proposed model, the boundary effect between moving objects and background is analyzed mathematically to overcome the limit of the spatially invariant model. And we present the motion-based image segmentation technique for the object-based image restoration, which is the modified version of the conventional segmentation method. Based on the proposed model, the restoration technique removes the motion blur by using the estimated motion parameter from the result of the segmentation.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.11
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• pp.62-69
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• 1998

The general degradation model has been applied to analyze the hot carrier induced degradation of the DC and RF characteristics of RF-nMOSFET. The degradation of cut-off frequency has been severer than the degradation of bulk MOSFET drain current. The value of the degradation rate n and the degradation parameter m for RF-nMOSFET has been equal to those for bulk MOSFET. The decrease of device degradation with the increase of fingers could be explained by the large source/drain parasitic resistance and drain saturation voltage. It has been also found that the RF performance degradation could be explained by the decrease of $g_{m}$ and $C_{gd}$ and the increase of $g_{ds}$ after stress. The degradation of the DC and RF characteristics of RF-nMOSFET could be predicted by the measurement of the substrate current.t.

• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.2531-2534
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• 2000

본 연구는 전동기의 부분방전에 의해 발생되는 전자파를 측정하여 전동기의 열화상태를 진단할 수 있는 전동기 절연열화진단시스템을 설계하는 방법을 제안하고자 한다. 따라서 부분방전에 의한 전자파를 측정하는 시스템을 구성하고, 측정된 데이터를 분석하여 정량화된 특징 데이터를 추출하고 생성된 데이터를 이용한 뉴로-퍼지 진단모델설계 방법을 제시한다. 그리고 제안된 방법에 의해 설계된 진단모델을 실측데이터를 통해 진단하여 그 타당성을 입증하고자 한다. 1단계 연구로, 본 연구에서는 현장 전동기의 전자파를 On-Line으로 계측하는 시스템을 구성하여 전동기의 절연체내에서 발생하는 부분방전에 의한 전자파를 계측하여 데이터로부터 전동기의 절연열화상태를 해석하여 절연 열화와의 관계를 분석하였다.