• Journal of the Korean Society of Safety
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• v.36 no.1
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• pp.18-25
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• 2021

In many developed countries, such as South Korea, efficiently maintaining the aging infrastructures is an important issue. Currently, inspectors visually inspect the infrastructure for maintenance needs, but this method is inefficient due to its high costs, long logistic times, and hazards to the inspectors. Thus, in this paper, a novel crack inspection approach for concrete bridges is proposed using integrated image processing techniques. The proposed approach consists of four steps: (1) training a deep learning model to automatically detect cracks on concrete bridges, (2) acquiring in-situ images using a drone, (3) generating orthomosaic images based on 3D modeling, and (4) detecting cracks on the orthmosaic image using the trained deep learning model. Cascade Mask R-CNN, a state-of-the-art instance segmentation deep learning model, was trained with 3235 crack images that included 2415 hard negative images. We selected the Tancheon overpass, located in Seoul, South Korea, as a testbed for the proposed approach, and we captured images of pier 34-37 and slab 34-36 using a commercial drone. Agisoft Metashape was utilized as a 3D model generation program to generate an orthomosaic of the captured images. We applied the proposed approach to four orthomosaic images that displayed the front, back, left, and right sides of pier 37. Using pixel-level precision referencing visual inspection of the captured images, we evaluated the trained Cascade Mask R-CNN's crack detection performance. At the coping of the front side of pier 37, the model obtained its best precision: 94.34%. It achieved an average precision of 72.93% for the orthomosaics of the four sides of the pier. The test results show that this proposed approach for crack detection can be a suitable alternative to the conventional visual inspection method.

• Smart Structures and Systems
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• v.32 no.5
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• pp.319-338
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• 2023

The study presents a new hybrid data-driven method by combining radial basis functions neural networks (RBF-NN) with the Jaya algorithm (JA) to provide effective structural health monitoring of arch dams. The novelty of this approach lies in that only one user-defined parameter is required and thus can increase its effectiveness and efficiency, as compared to other machine learning techniques that often require processing a large amount of training and testing model parameters and hyper-parameters, with high time-consuming. This approach seeks rapid damage detection in arch dams under dynamic conditions, to prevent potential disasters, by utilizing the RBF-NNN to seamlessly integrate the dynamic elastic modulus (DEM) and modal parameters (such as natural frequency and mode shape) as damage indicators. To determine the dynamic characteristics of the arch dam, the JA sequentially optimizes an objective function rooted in vibration-based data sets. Two case studies of hyperbolic concrete arch dams were carefully designed using finite element simulation to demonstrate the effectiveness of the RBF-NN model, in conjunction with the Jaya algorithm. The testing results demonstrated that the proposed methods could exhibit significant computational time-savings, while effectively detecting damage in arch dam structures with complex nonlinearities. Furthermore, despite training data contaminated with a high level of noise, the RBF-NN and JA fusion remained the robustness, with high accuracy.

• The Korean Journal of Community Living Science
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• v.28 no.3
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• pp.391-401
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• 2017

This study was conducted to evaluate the relationships between exposure level to pyrethroid pesticide and wearing of protective equipment in 194 Chung-nam orchard male farmers. The urinary metabolites of pyrethroid pesticides, including Cis, Trans, DBCA, and 3-PBA, were analyzed by GC/MSD. As a result of this study, the detection rate and exposure level of 3-PBA was the highest among pyrethroid metabolites discovered by orchard farmers. As a result of analyzing the actual conditions of wearing protective equipment by the subjects of this study, the rate of agricultural farmers who wore four pieces of protective equipment compared to agricultural farmers wearing a single piece of protective clothing was as high as 35.1%. Pyrethroid exposure levels were low when farmers wore more personal protective equipment (PPE). In conclusion, training with regards to pesticide hazards and protective equipment for farmers who spray pesticides will help reduce pesticide exposure levels.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.366-368
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• 2000

When faults occur in transmission lines, the classification of faults is very important. If the fault is HIF(High Impedance Fault), it cannot be detected or removed by conventional overcurrent relays (OCRs), and results in fire hazards and causes damages in electrical equipment or personal threat. The fast discrimination of fault needs to effective protection and treatment and is important problem for power system protection. This paper proposes the fault detection and discrimination algorithm for LIFs(Low Impedance Faults) and HIFs(High Impedance Faults). This algorithm uses artificial neural networks and variation of 3-phase maximum currents per period while faults. A double lines-to-ground and line-to-line faults can be detected using Neural Network. Also, the other faults can be detected using the value of variation of maximum current. Test results show that the proposed algorithms discriminate LIFs and HIFs accurately within a half cycle.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.8A
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• pp.1208-1217
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• 1999

Being increased the errention and competition for communication business, the economical efficiency and the reliance of communication network were raised. The communication operators are sensitively reactioned to the data related communication. Especially, the trend of hazards related to communication networks and users is broadly deviede into 3 classes in the technical specificatons of foreigners. In this paper, the field data of parameters corresponding to 3 classes was statistically processed and compared to the specified values in the technical specification. The ststistical processes of field data play a role as an objective information for the service quality related to the communication network, and will be helpful for preparing the globalization of communication.

• Journal of Fisheries and Marine Sciences Education
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• v.28 no.3
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• pp.713-726
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• 2016

This study were attempted to apply the HACCP system adopted in the dried anchovy workplace to ensure the hygiene safety of dried anchovy workplace. In this study, HACCP system procedures, including HACCP team organization, determination of critical control point(CCP), establishment of critical limits, mornitering and verification etc., were established using KFDA 12 procedures. To determine whether hazards were critical elements, we evaluated the likelihood and seriousness of each hazard element. The likelihood of residual microorganism and metal piece exceeding the acceptable limit in dried anchovy products were demonstrated to be a critical hazard element. Management of the boiling(CCP-1B) and metal detection(CCP-2P) were determined to be a critical control point. The standards for acceptable residual microorganism and metal piece were set based on relevant laws and regulations, and then the limits were adapted and established for the CCP. An HACCP plan applicable to dried anchovy workplace was established.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.2
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• pp.179-186
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• 2012

The potential hazards resulting from a low-velocity impact(bird-strike, tool drop, runway debris, etc.) on aircraft structures, such as engine nacelle or leading edges has been a long-term concern to the aircraft industry. Certification authorities require that exposed aircraft components must be tested to prove their capability to withstand low-velocity impact without suffering critical damage. In most of the past research studies unloaded specimens have been used for impact tests, however, in reality it is much more likely that a composite structure is exposed to a certain stress state when it is being impacted, which can have a significant effect on the impact performance. And the radiated impact sound induced by impact is analyzed for the damage detection evaluation. In this study, an investigation was undertaken to evaluate the effect in-plane loading on the impact force and sound of composite laminates numerically.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.51 no.5
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• pp.524-534
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• 2018

This study assessed the biological and physicochemical hazards involved in establishing a hazard analysis critical control point (HACCP) for canned seasoned Broughton's ribbed ark Scapharca broughtonii and examined the critical control points (CCPs) in the field. Following the basic principles of the HACCP system, the hazard-evaluation procedures were enacted during the production of canned seasoned Broughton's ribbed ark after field investigation of a seafood product company in Korea. CCPs were determined using canned seasoned Broughton's ribbed ark with the corresponding control measures. The HACCP system was applied to each step in processing the product. The results indicated that inspection of raw materials, filling, sterilization, and alien substance detection were the most important CCPs. These results can be used to prevent and control food safety problems in the production of canned seasoned Broughton's ribbed ark.

• Environmental Engineering Research
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• v.22 no.2
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• pp.131-140
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• 2017

The use of electronic cigarettes (ECs) is recognized as a source of many pollutants, just like conventional cigarettes (CCs). The analysis of EC aerosol samples has confirmed the presence of various metallic species. Most of these metals originate from various parts of the cartomizer, e.g., solder joints, wires, and silicate beads. The metal concentration levels in EC samples were shown to be generally two to four orders of magnitude lower than those of CCs. However, the use of ECs can still pose significant human health hazards as consumers are exposed to the toxicity of those metals and many other hazardous pollutants released simultaneously via the vaping of ECs. The review also describes the detection and quantification of various metals in ECs and CCs. This review was carried out to assess the level of metal species released from ECs and to suggest proper guidelines to control consumer exposure.

• Journal of Aerospace System Engineering
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• v.11 no.1
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• pp.35-40
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• 2017

Aircraft diagnostic systems identify system failures and nip aircraft accidents in the bud by removing hazards that hinder Safety Of Flight (SOF). The necessity for diagnostic systems is increasing as aircraft manufacturing technology is modernized. Many countries have conducted studies and developed diagnostic systems. However, studies about diagnostic systems are very few in Korea. This study defines the scope of aircraft diagnostics systems and closely considers methods to ensure the Safety Of Flight (SOF) for military aircraft.