• 대한기계학회논문집A
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• 제20권12호
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• pp.3767-3781
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• 1996

Generally, dynamic loads are applied to real structures. Since the analysis with the dynamic load is extremely difficult, static loads are utilized by proper conversions of the dynamic loads. The dynamic loads are usually converted ot static loads by safety foactors of experiences. However, it may increase weight and decrease reliability. In this study, a method is proposed for the conversion process. An equivalent static load is calculated ot generate a same maximum displacement. The method is verified through numerical tests on a spring-mass systems of one and multi degrees-of freedom. It has been found that the duration time of the loads and the natural frequencies of the structures are critical in the conversion process. A road arem is a self-propelled howizer is selected for the application of the proposed method. The shape of the road arm is optimized under the converted static loads.

• 방재&안전
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• 제5권1호
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• pp.93-100
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• 2015

Although many years passed since 'The Legislative bill on the support of voluntary activities of enterprises for disaster reduction'(hereinafter referred to as 'enterprise disaster reduction act') has been first enacted in 2007, BCMS is still not activated in our society. In contrast, after 911 Terror, importance of BCM is getting magnified and standardization research & institutionalization i s a lso proceeding i all over world. Lately, Disaster preventing activities is urgently needed like the sinking of 'Sewol ferry'. So the purpose of this paper is proposed for establishment of 'BCMS' and activation of the certificate system for Best-Run Business by analyzing the problem of 'enterprise disaster reduction act' and weak of activation as following. First, propel changing the policy of self-regulated participation to mandatory about the certificate system for Best-Run Business from public entity to government ministry and it is able to activate by propelling demo business of the certificate system for Best-Run Business. Second, public entity that has been given the certificate system for Best-Run Business by affiliating with Disaster Management Assessment of government management can be exempted from Disaster Management Assessment or those entity can arrange for connectivity acquisition method of 'Excellent rate'. Third, to publicize the activation of the law mentioned above, makes public entity r ecognizable by incorporating 'BCMS' into National safety management plan and establishment of National critical infrastructures security plan. Fourth, it should be reviewed to improving the related act regarding to inclusion of public organizations as well as private enterprises.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.614-615
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• 2007

There are roughly a hundred types of cables in power plants. The distribution of circuits in a nuclear plant is comprised of 20% instrument cables, 61% control cables, 13% AC power cables, 1% DC power cables, and 5% communication lines. In the nuclear power plant, medium voltage cables are generally included in the scope of systems reviewed for safety and are included in a plant's maintenance program. Medium voltage cables provide power to many critical components in plants, including feed water pumps, circulating water pumps, and condensate pumps. Among these cables, high temperature sections of cables feeding electrical power to the circulating water pump and the condenser extraction pump were found. The evaluation for these cables is performed to find the maximum allowable current and temperature. The result shows that the load current flowed about 85% of the allowable current ampacity, and the temperature of conductor at full load current did not exceed the limited temperature. Therefore, existing cables for circulating water pump and condenser extraction pump system are going to be used during design life.

• 전자통신동향분석
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• 제34권6호
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• pp.51-60
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• 2019

As a way to further expand and enable the 5G ecosystem, the $3^{rd}$ Generation Partnership Project (3GPP) is considering the development of a 5G new radio (NR)-based non-terrestrial network (NTN). These NTNs are expected to provide ubiquitous 5G services to user's equipment (especially, in Internet of Things/machine-type communications (IoT/MTC) public safety, and critical communications) by extending service coverage to areas not covered by 5G terrestrial networks. To this end, this NTN is developing scenarios to provide 5G services using spaceborne vehicles, such as geosynchronous and low-Earth orbit satellites, and airborne vehicles, such as unmanned aircraft systems, including high-altitude pseudo-satellites. In addition, various technologies are being studied to satisfy new requirements not considered in 5G NR, such as long propagation delay time, large cell coverage, large Doppler effect, and base station movement. In this paper, we present the scenarios, requirements, technical issues and solutions, and standardization planning for NR-based NTN in 3GPP.

• International Journal of Computer Science & Network Security
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• 제21권8호
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• pp.167-176
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• 2021

This is the world of computer science and innovations. In this modern era, every day new apps, webs and software are being introduced. As well as new apps and software are being introduced, similarly threats and vulnerable security matters are also increasing. Web apps are software that can be used by customers for numerous useful tasks, and because of the developer experience of good programming standards, web applications that can be used by an attacker also have multiple sides. Web applications Security is expected to protect the content of critical web and to ensure secure data transmission. Application safety must therefore be enforced across all infrastructure, including the web application itself, that supports the web applications. Many organizations currently have a type of web application protection scheme or attempt to build/develop, but the bulk of these schemes are incapable of generating value consistently and effectively, and therefore do not improve developers' attitude in building/designing stable Web applications. This article aims to analyze the attacks on the website and address security scanners of web applications to help us resolve web application security challenges.

• 한국지진공학회논문집
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• 제26권1호
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• pp.39-48
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• 2022

Many piping systems installed in the power plant are directly related to the safety and operation of the plant. Various dampers have been applied to the piping system to reduce the damage caused by earthquakes. In order to reduce the vibration of the piping system, this study developed a steel coil damper (SCD) with a straightforward structure but excellent damping performance. SCD reduces the vibration of the objective structure by hysteretic damping. The new SCD damper can be applied to high-temperature environments since it consists of steel members. The paper introduces a design method for the elastoplastic coil spring, which is the critical element of SCD. The practical applicability of the design procedure was validated by comparing the nonlinear force-displacement curves calculated by design equations with the results obtained from nonlinear finite element analysis and repeated loading test. It was found that the designed SCD's have a damping ratio higher than 25%. In addition, this study performed a set of seismic tests using a shaking table with an existing piping system to verify the vibration control capacity on the piping system by SCD. Test results prove that the SCD can effectively control the displacement vibration of the piping system up to 80%.

• Nuclear Engineering and Technology
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• 제55권3호
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• pp.827-838
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• 2023

Centrifugal pump is a key part of nuclear power plant systems, and its health status is critical to the safety and reliability of nuclear power plants. Therefore, fault diagnosis is required for centrifugal pump. Traditional fault diagnosis methods have difficulty extracting fault features from nonlinear and non-stationary signals, resulting in low diagnostic accuracy. In this paper, a new fault diagnosis method is proposed based on the improved particle swarm optimization (IPSO) algorithm-based variational modal decomposition (VMD) and relevance vector machine (RVM). Firstly, a simulation test bench for rotor faults is built, in which vibration displacement signals of the rotor are also collected by eddy current sensors. Then, the improved particle swarm algorithm is used to optimize the VMD to achieve adaptive decomposition of vibration displacement signals. Meanwhile, a screening criterion based on the minimum Kullback-Leibler (K-L) divergence value is established to extract the primary intrinsic modal function (IMF) component. Eventually, the factors are obtained from the primary IMF component to form a fault feature vector, and fault patterns are recognized using the RVM model. The results show that the extraction of the fault information and fault diagnosis classification have been improved, and the average accuracy could reach 97.87%.

• Smart Structures and Systems
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• 제31권5호
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• pp.501-516
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• 2023

Dynamic irregularity and acceleration of bridges subjected to high-speed trains provide crucial information for comprehensive evaluation of the health state of under-track structures. This paper proposes a novel approach for real-time estimation of vertical track dynamic irregularity and bridge acceleration using deep generative adversarial network (GAN) and vibration data from in-service train. The vehicle-body and bogie acceleration responses are correlated with the two target variables by modeling train-bridge interaction (TBI) through least squares generative adversarial network (LSGAN). To realize supervised learning required in the present task, the conventional LSGAN is modified by implementing new loss function and linear activation function. The proposed approach can offer pointwise and accurate estimates of track dynamic irregularity and bridge acceleration, allowing frequent inspection of high-speed railway (HSR) bridges in an economical way. Thanks to its applicability in scenarios of high noise level and critical resonance condition, the proposed approach has a promising prospect in engineering applications.

• International Journal of Advanced Culture Technology
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• 제11권4호
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• pp.406-416
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• 2023

Alarm system performance is a critical aspect of safety. While existing research has extensively examined the influence of acoustic attributes on alarm performance, consonance's impact remains largely uncharted territory. This study bridges this research gap by investigating the effect of consonance on alarm systems. We extend our investigation to encompass not only the sound characteristics of the alarm but also the acoustic qualities of the surrounding environment, recognizing their potential impact on alarm efficacy. Prior studies consistently link consonance to annoyance levels, resulting in a negative user experience. Thus, we explore the relationship between consonance and alarm system performance, with a particular focus on modulating annoyance as an explanatory factor. Utilizing an oddball paradigm, we categorized standard and oddball sounds into consonant and dissonant types, creating four sound combinations. Participants were asked to respond to the irregularly presented oddball sounds while ignoring the constantly presented standard sounds. Our results reveal significant differences between groups, with the Standard Consonant/Oddball Dissonant (SC/OD) group displaying notably slower response times than the Standard Dissonant/Oddball Consonant (SD/OC) group. This reaction time variation aligns with differences in annoyance levels, as the SC/OD group reports higher annoyance, suggesting that reaction time discrepancies may be linked to increased arousal due to heightened annoyance.

• 한국산업융합학회 논문집
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• 제27권3호
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• pp.701-707
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• 2024

Industry 4.0 has brought about significant changes in the roles of workers through the introduction of innovative technologies. In smart factory environments, workers are required to interact seamlessly with robots and automated systems, often utilizing equipment enhanced by Virtual Reality (VR) and Augmented Reality (AR) technologies. This study aims to systematically analyze recent research literature on monitoring the physical and mental states of workers in Industry 4.0 environments. Relevant literature was collected using the Web of Science database, employing a comprehensive keyword search strategy involving terms related to Industry 4.0 and health monitoring. The initial search yielded 1,708 documents, which were refined to 923 journal articles. The analysis was conducted using VOSviewer, a tool for visualizing bibliometric data. The study identified general trends in the publication years, countries of authors, and research fields. Keywords were clustered into four main areas: 'Industry 4.0', 'Internet of Things', 'Machine Learning', and 'Monitoring'. The findings highlight that research on health monitoring of workers in Industry 4.0 is still emerging, with most studies focusing on using wearable devices to monitor mental and physical stress and risks. This study provides a foundational overview of the current state of research on health monitoring in Industry 4.0, emphasizing the need for continued exploration in this critical area to enhance worker well-being and productivity.