• Journal of the Korean Institute of Intelligent Systems
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• v.20 no.2
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• pp.189-194
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• 2010

In the recommendation system that recommends services to a specific user by using the estimation value of other users for users' recommendation service, collaborative filtering methods are widely used. But such recommendation systems have problems that exact classification is not possible because a specific user is classified to already classified group in the course of clustering and inexact result can be recommended in case of big errors in users' estimation values. In this paper, in order to increase estimation accuracy, the researchers suggest a recommendation system that applies collaborative filtering after reclassifying on the basis of a specific user's classification items and then finding and correcting the estimation values of the users beyond the critical value of time. This system uses a method where a specific user is not classified to already classified group in the course of clustering but a group is reorganized on the basis of the specific user. In addition, the researchers correct estimation information by cutting off the subordinate 10% from the trimmed mean of samples and then applies weight over time to the remaining data. As the result of an experiment, the suggested method demonstrated about 14.9%'s more accurate estimation result in case of using MAE than general collaborative filtering method.

• Journal of the Society of Disaster Information
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• v.17 no.4
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• pp.864-881
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• 2021

Purpose: This study aims is to provide a total care solution preventing disaster based on Big Data and AI technology and to service safety considered by individual situations and various risk characteristics. The purpose is to suggest a method that customized comprehensive index services to prevent and respond to safety accidents for calculating the living safety index that quantitatively represent individual safety levels in relation to daily life safety. Method: In this study, we use method of mixing AHP(Analysis Hierarchy Process) and Likert Scale that extracted from consensus formation model of the expert group. We organize evaluation items that can evaluate life safety prevention services into risk indicators, vulnerability indicators, and prevention indicators. And We made up AHP hierarchical structure according to the AHP decision methodology and proposed a method to calculate relative weights between evaluation criteria through pairwise comparison of each level item. In addition, in consideration of the expansion of life safety prevention services in the future, the Likert scale is used instead of the AHP pair comparison and the weights between individual services are calculated. Result: We obtain result that is weights for life safety prevention services and reflected them in the individual risk index calculated through the artificial intelligence prediction model of life safety prevention services, so the comprehensive index was calculated. Conclusion: In order to apply the implemented model, a test environment consisting of a life safety prevention service app and platform was built, and the efficacy of the function was evaluated based on the user scenario. Through this, the life safety index presented in this study was confirmed to support the golden time for diagnosis, response and prevention of safety risks by comprehensively indication the user's current safety level.

• Journal of Digital Convergence
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• v.19 no.4
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• pp.151-157
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• 2021

Recently, IoT technology has been applied to various cloud environments, requiring accurate verification of various information generated by IoT devices. However, due to the convergence of IoT technologies and 5G technologies, accurate analysis is required as IoT information processing is rapidly processed. This paper proposes a blockchain-based multi-IoT verification model for overlay cloud environments. The proposed model multi-processes IoT information by further classifying IoT information two layers (layer and layer) into bits' blockchain to minimize the bottleneck of overlay networks while ensuring the integrity of information sent and received from embedded IoT devices within local IoT groups. Furthermore, the proposed model allows the layer to contain the weight information, allowing IoT information to be easily processed by the server. In particular, transmission and reception information between IoT devices facilitates server access by distributing IoT information from bits into blockchain to minimize bottlenecks in overlay networks and then weighting IoT information.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.2
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• pp.238-247
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• 2023

Liquefied petroleum gas (LPG) is an attractive fuel for ships considering its current technology and economic viability. However, safety guidelines for LPG-fueled ships are still under development, and there have been no cases of applying LPG propulsion systems to small and medium-sized ships in Korea. The purpose of this study was to perform an objective risk assessment for the first marine LPG engine system and propose safe operational standards. First, hazard and operability (HAZOP) analysis was used to divide the engine system into five nodes, and 58 hazards were identified. To compensate for the subjectivity of qualitative evaluation using HAZOP analysis, fuzzy set theory was used, and additional risk factors, such as detectability and sensitivity, were included to compare the relative weights of the risk factors using a fuzzy analytical hierarchy process. As a result, among the five risk factors, those with a major impact on risk were determined to be the frequency and severity. Finally, the fuzzy technique for order of preference by similarity to ideal solution (TOPSIS) was applied to select the risk rank more precisely by considering the weights of the risk factors. The risk level was divided into 47 groups, and the major hazard during the operation of the engine system was found through the analysis to be gas leakage during maintenance of the LPG supply line. The technique proposed can be applied to various facilities, such as LPG supply systems, and can be utilized as a standard procedure for risk assessment in developing safety standards for LPG-powered ships.

• Korean Journal of Construction Engineering and Management
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• v.25 no.3
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• pp.3-16
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• 2024

The government announced the Housing Welfare Roadmap (November 2017), to expand the supply of public rental housing by reconstructing aged long-term public rental complexes. Also, remodeling projects for complexes with low business feasibility of reconstruction projects are recognized as an alternative to supplying public rental housing in urban area. This study analyzed influence factors by dividing them into project feasibility, architectural plan, urban & residential environment plan, and legal system groups in order to establish a plan for long-term public rental housing remodeling project. Futhermore, this work conducted the principal component analysis to get the principal component factors among the influence factors of each group, and the weight analysis to calculate weighting of them. In addition, major influence factors were derived by calculating the relative importance score (RIS) of each factor. Lastly this paper validated the major influence factors and applicability of the procedure to select 3 complexes that can be reviewed for remolding project among 33 long-term public rental housing complexes located in Seoul. The results of this study are expected to be useful when establishing a remodeling project plan for long-term public rental housing.

• Journal of KIISE:Software and Applications
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• v.29 no.6
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• pp.417-424
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• 2002

Automatic text categorization is a problem of assigning predefined categories to free text documents. In order to classify text documents, we have to extract good features from them. In previous researches, a text document is commonly represented by the frequency of each feature. But there is a difference between important and unimportant sentences in a text document. It has an effect on the importance of features in a text document. In this paper, we measure the importance of sentences in a text document using text summarizing techniques. A text document is represented by features with different weights according to the importance of each sentence. To verify the new method, we constructed Korean news group data set and experiment our method using it. We found that our new method gale a significant improvement over a basis system for our data sets.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.6B
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• pp.358-366
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• 2007

Recently, FCC(Federal Communications Commission) has considered for that unlicensed device leases licensed devices' channel to overcome shortage of communication channels. Therefore, IEEE 802.22 WRAN(Wireless Regional Area Networks) working group progresses CR (Cognitive Radio) technique that is able to sense and adopt void channels that are not being occupied by the licensed devices. Channel selection is of the utmost importance because it can affect the whole system performance in CR network. Thus, we propose a policy-based dynamic channel selection architecture for cognitive radio network to achieve an efficient communication. We propose three kinds of method for channel selection; the first one is weighted channel selection, the second one is sequential channel selection, and the last one is combined channel selection. We can obtain the optimum channel list and allocates channels dynamically using the proposed protocol.

• Journal of the Korea Convergence Society
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• v.11 no.4
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• pp.33-39
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• 2020

Interest in 5G communication security has been growing recently amid growing expectations for 5G technology with faster speed and stability than LTE. However, 5G has so far included disparate areas, so it has not yet fully supported the issues of security. This paper proposes a blockchain-based IoT management model in order to efficiently provide the authentication of users using IoT in 5G In order to efficiently fuse the authentication of IoT users with probabilistic theory and physical structure, the proposed model uses two random keys in reverse direction at different layers so that two-way authentication is achieved by the managers of layers and layers. The proposed model applied blockchain between grouped IoT devices by assigning weights to layer information of IoT information after certification of IoT users in 5G environment is stratified on a probabilistic basis. In particular, the proposed model has better functions than the existing blockchain because it divides the IoT network into layered, multi-layered networks.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.06a
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• pp.361-367
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• 2004

For assessment of tritium and radiocarbon ingestion dose to off site individuals, water, hydrogen, and carbon content of main farm produce of Korea were investigated to replace the existing data in K-DOSE60, the Offsite Dose Calculation Manual (ODCM) of Korea Hydro ＆ Nuclear Power Co. Ltd, (KHNP). Main items and weighting factors of farm produce were determined with the nationwide food intake data in 2001, 2002. Main farm produce were sampled around Kori, Wolsong, Ulchin, Younggwang nuclear power sites, Content of each produce was multiplied by weighting factor and summed up to make the weighted mean group value For grains, water, hydrogen, and carbon content was not much different from the existing data currently used in K-DOSE60, but root vegetables had 3.5 times more hydrogen, and leafy vegetables and fruits had 0.7∼1.3 times more or less water, hydrogen, and carbon contents than K-DOSE60.

• The Journal of the Korea Contents Association
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• v.17 no.6
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• pp.22-31
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• 2017

This study has begun with the perception that proper measuring system is required to grow community business in equilibrium and to grope for some developmental directions of it. First, for effective performance evaluation of community business, the study developed a performance evaluation model based on balanced score cards, and to apply validity analysis and analytic hierarchy process (AHP) by classifying. Second, the relative importance of the second indicator for each of the first aspects shows that participation of local residents and in the aspect of person interested, satisfaction of inner education in the aspect of learning and growth, shortening of work process in the aspect of inner process, and sales per head in the aspect of substantiality were high in relative importance. Third, in the result of calculation of overall weight for each aspect, participation of local residents, a business connection to the community, sales per head were ranked in the upper group. Thus, it's now necessary to have management support through fostering intermediate support organizations in community business which has been bureaucratic, and improvement of product and service through connection with outside consulting agencies and strategic alliance with the leading businesses is required.