• 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 Journal of the Convergence on Culture Technology
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• v.9 no.6
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• pp.495-507
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• 2023

The purpose of this study is to identify the current status of legal disputes that occur while firefighters are performing their duties and to suggest efficient response measures. To investigate awareness of legal disputes, a survey was conducted on 3,500 firefighters, and the responses of 505 people who participated in the survey were analyzed. As a research method, frequency analysis and cross-analysis were conducted based on the demographic characteristics of the participants and a survey of firefighters' awareness of the law, and through this, basic statistics and status were analyzed. As a result of the analysis, it was found that firefighters feel a lot of burden, including time and material losses, as well as disadvantages and mental anxiety in the workplace when legal disputes occur while performing their duties. The need for an organizational response in the workplace as an efficient response to this was statistically confirmed. Therefore, based on the results of this study, we propose the permanent establishment and operation of a professional legal support team within each city/provincial fire department headquarters so that firefighters can concentrate on their duties free from legal disputes.

• Journal of Industrial Convergence
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• v.22 no.4
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• pp.65-73
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• 2024

The purpose of this study was to identify the effect of job resources of hospital workers on presenteeism and to verify the mediating effect of job embeddedness based on this. Participants included 301 hospital workers form hospitals located in B city. Date was collected form July 10 to August 10, 2023. The collected data were analyzed by frequency analysis, descriptive statistics, Pearson's correlation coefficient, Baron and Kenny's three-step hierarchical regression and Sovel's test method using the SPSS 26.0 program. In this study, it was found that there was a correlation between job resources, job embeddedness and presenteeism of hospital workers, job resources and job embeddedness influenced negatively on presenteeism, and it was confirmed that job embeddedness partially mediated in the relationship between job resources and presenteeism. Based on this, in order to reduce presenteeism of hospital workers. it was suggested to improve job integrity by providing sufficient job resources institutionally an administratively and providing continuous educational opportunities.

• Journal of Environmental Science International
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• v.33 no.9
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• pp.645-665
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• 2024

For volatile organic compounds (VOCs) emanating from workplaces within the Noksan national industrial complex, the emission characteristics of pollutants were identified through zone-based measurements using vehicles equipped with selective ion flow tube mass spectrometry(SIFT-MS). The average concentration of total VOCs was higher in zones 2, 4, and 5 than in zones 1, 3, and 6, and was 2.1 to 4.2 times higher than background concentrations. The average concentrations of pollutants investigated were (from highest to lowest) methyl ethyl ketone, formaldehyde, methanol, and n-hexane. However, the pollutants that should be prioritized for reduction to decrease ozone generation were (from highest to lowest) methyl ethyl ketone, n-hexane, for maldehyde, and ethylbenzene+xylene. Benzene, a substance governed by atmospheric environmental standards, exhibited a frequency distribution exceeding the stipulated limits, and concentrations exceeding 100 ppb were identified for methyl ethyl ketone, methanol, toluene, and n-hexane. In certain class 4 and 5 workplace facilities, VOC emissions and emission prevention installations were inadequately managed, necessitating the formulation of management measures for small enterprises. Also, workplaces that emit large amounts of VOCs need to upgrade to VOC-prevention installations with higher processing efficiencies. To efficiently monitor VOCs in a wide range of areas, such as the Noksan national industrial complex, it is considered appropriate to monitor workplaces that emit high concentrations of VOCs using mobile SIFT-MS in real time rather than relying on fixed monitoring methods. A specialized method targeting approximately 10 VOCs is necessary to quickly track emission sources.Furthermore, it is essential to phase in a system for the intensive management of suspected workplaces based on accumulated data from SIFT-MS in areas where high VOC concentrations are measured and to establish a cooperative system for sharing data between relevant institutions.

• Journal of the Korea Concrete Institute
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• v.21 no.2
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• pp.187-197
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• 2009

This paper presents a systematic approach for estimating fragility curves and damage probability matrices for different frequencies. Fragility curves and damage probability indicate the probabilities that a structure will sustain different degrees of damage at different ground motion levels. The seismic damages are to achieved by probabilistic evaluation because of uncertainty of earthquakes. In contrast to previous approaches, this paper presents a method that is based on nonlinear dynamic analysis of the structure using empirical data. This paper presents the probability of damage as a function of peak ground acceleration and estimates the probability of five damage levels for prestressed concrete (PSC) bridge pier subjected to given ground acceleration. At each level, 100 artificial earthquake motions were generated in terms of soil conditions, and nonlinear time domain analyses was performed for the damage states of PSC bridge pier structures. These damage states are described by displacement ductility resulting from seismic performance based on existing research results. Using the damage states and ground motion parameters, five fragility curves for PSC bridge pier with five types of dominant frequencies were constructed assuming a log-normal distribution. The effect of dominant frequences was found to be significant on fragility curves.

• Journal of KIISE:Information Networking
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• v.34 no.5
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• pp.405-422
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• 2007

Recently, according to the network environment, there are many researches for home network. Nowadays, in home network, the method that access control policy is managed for each home device by using ACL is popular, and EAM (Extranet access management) is applied as a solution. In addition, the research about secure OS is ongoing based on open operating system and the research of user authentication mechanisms for home network using home server is also in progress. However, these researches have some problems as follows; First, the transmission scope of expected access technology in home network is wide, so unauthenticated outside terminal can access the home network. Second, user is inconvenient because user need to set the necessary information for each device. Third, user privacy and convenience are not considered. OSGi provides a service platform for heterogeneous technologies in home network environment. Here, user access control is one of the core parts which should have no problems such as above items, but there are no concrete researches yet. Thus in this paper, we propose an access control policy management framework and access control operation based on RBAC for user access control in home network environment in which OSGi service platform is operated. First, we list the consideration which is not clearly mentioned in OSGi standard, and then we solve these above problems through new framework. In addition, we propose the effective and economical operation method which reduces the policy change frequency for user access control by using RBAC concept though limited resource of home gateway. Besides, in this paper, these proposed policies are defined separately as user-role assignment policy and permission-role assignment policy, and user decide their own policies. In conclusion, we provide the scheme to enhance the user convenience and to solve the privacy problem.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.5
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• pp.703-711
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• 2013

The effort for identifying personal information for example one's personality, based on one's handwriting has been continued in foreign countries, however, there is no research on the graphology for Korean in Korea. In the area of handwriting analysis, of course, they have made attempts to identifying people depended on expert's individual ability or judgment. For these reasons, the academic approach is needed for the graphology for Korean. In this thesis, we performed the frequency analysis, test of difference, cross tabulation analysis, factor analysis, correlation analysis, regression analysis and logistic regression analysis by using the data on the test of personality diagnosis based on 5 factors method and writing habits such as the size and slope of letters for 339 adults. It can be shown that the 5 factors method has high consistency and reliability, so we accept these 5 factors as the personalities. In cross tabulation analysis, it is found that there is significant relationship between sex and the size of letters, hometown and the margin, job and habit. The correlations between 5 factors are very high and we can find the useful relationships between 5 factors and writing habit through regression analysis and correlation analysis. It is difficult and impossible to compare the Graphology between English and Korean because there are various interpretations and structures of Korean that is much different from those of English. But it is very important to try to test and analyze the Graphology in Korean to found the basic theories at the present stage when there is no research on the graphology for Korean.

• The Journal of the Korea Contents Association
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• v.16 no.10
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• pp.483-491
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• 2016

This study aims to consider the display method of the STA information that holds aesthetic cultural distinctiveness with the capability of immediate recognition of information in the relationship between the exposed time and the degree of cognition. As an consideration on the display method of information in an efficient way according as 'information attributes', the purpose of this study is to identify the visualization attributes of the STA information and to seek out display methods accordingly. Based on the information design and cognitive psychology, the cognitive features of the STA information have been identified and four visualization attributes of the STA information have been found based on the preceding studies on the information attributes in line with the relationship between exposure frequency and the level of awareness. In terms of information recognition, a metaphor, metonymy, use of indexical image and context, rhetoric, and Mnemonic have been proposed as major display methods for 'Understandable' and 'Conciseness', which are the major visualization attributes of the STA information while humor, parody, distinctiveness, friendliness, kitsch, formative beauty and newness have been suggested as the major display methods of 'Relevance' and 'Valuable', which are the major visualization attributes from the perspective of sensitive perception of information. Based on the results of this study, I'm planning to come up with display methods and to proceed with analyzing the relationship of the degree of cognition in association with context.

• Journal of KIISE:Software and Applications
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• v.29 no.11
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• pp.837-850
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• 2002

In this paper, we propose an EEG-based response time prediction method during a yes/no cognitive decision task. In the experimental task, a subject goes through responding of visual stimulus, understanding the given problem, controlling hand motions, and hitting a key. Considering the subject's varying brain activities, we model subjects' mental states with defining CT (cut time), ST (selection time), and RP (repeated period). Based on the assumption between ST and RT in the mental model, we predict subjects' response time by detection of selection time. To recognize the subjects' selection time ST, we extract 3 types of feature from the filtered brain waves at frequency bands of $\alpha$, $\beta$, ${\gamma}$ waves in 4 electrode pairs combined by spatial relationships. From the extracted features, we construct specific rules for each subject and meta rules including common factors in all subjects. Applying the ST detection rules to 8 subjects gives 83% success rates and also shows that the subjects will hit a key in 0.73 seconds after ST detected. To validate the detection rules and parameters, we test the rules for 2 subjects among 8 and discuss about the experimental results. We expect that the proposed detection method can be a basic technology for brain-computer-interface by combining with left/right hand movement or yes/no discrimination methods.

• Journal of the Korea Society of Computer and Information
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• v.16 no.10
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• pp.147-153
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• 2011

In this paper, we present a new video management technique using forward timeline to efficiently store and delete the videos on a local server. The proposed method is based on capturing the changing preference of the videos according to recentness, frequency, and playback length of the requested videos. For this purpose, we utilize the forward timeline which represents the time area within a number of predefined intervals. The local server periodically measures time popularity and request segment of all videos. Based on the measured data, time popularity and request segment, the local server calculates the mean time popularity and mean request segment of a video using forward timeline. Using mean time popularity and mean request segment of video, we estimate the ranking and allocated storage space of a video. The ranking represents the priority of deletion when the storage area of local server is running out of space and the allocated storage space means the maximum size of storage space to be allocated to a video. In addition, we propose an efficient storage space partitioning technique in order to stably store videos and present a time based free-up storage space technique using the expected variation of video data in order for avoiding the overflow on a local server in advance. The simulation results show that the proposed method performs better than other methods in terms of hit rate and number of deletion. Therefore, our video management technique for local server provides the lowest user start-up latency and the highest bandwidth saving significantly.