• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.2
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• pp.87-94
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• 2023

As the latest weapon systems and electronic equipments are increasingly demanding stealth technology to improve the survivability of allies, it is necessary to implement low-observability technology that reduces the radar cross section(RCS). In order to implement this stealth technology, a method for low RCS characteristics by applying a shape design or a electromagnetic wave absorber is widely used. However, active phased array antennas have structural limitations in shape design, also when a absorber is applied to it, the performance of the antenna is degraded. Therefore, in this paper, in order to realize the low RCS characteristics of the active phased array antenna operating in the X-band, individual radiating elements suitable for applying the radio wave absorber were selected, and a 13x13 array antenna was designed and manufactured. Next, by comparing the measured results of the relative RCS and electrical performance for the manufactured antenna according to the presence and type of the absorber, it is shown that the electrical performance is maintained at an equal or higher level while obtaining the low RCS characteristics. Thereby the method proposed in this paper for implementing the low RCS characteristics was validated. Finally, it was confirmed that when the wave absorber is applied to the array antenna, the limitation of its performance deterioration can be overcome.

• Design Convergence Study
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• v.15 no.6
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• pp.195-214
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• 2016

Predictive analysis is based on a probabilistic learning algorithm called pattern recognition or machine learning. Therefore, if users want to extract more information from the data, they are required high statistical knowledge. In addition, it is difficult to find out data pattern and characteristics of the data. This study conducted statistical data analyses and visual data analyses to supplement prediction analysis's weakness. Through this study, we could find some implications that haven't been found in the previous studies. First, we could find data pattern when adjust data selection according as splitting criteria for the decision tree method. Second, we could find what type of data included in the final prediction model. We found some implications that haven't been found in the previous studies from the results of statistical and visual analyses. In statistical analysis we found relation among the multivariable and deducted prediction model to predict high box office performance. In visualization analysis we proposed visual analysis method with various interactive functions. Finally through this study we verified final prediction model and suggested analysis method extract variety of information from the data.

• Journal of Korean Tunnelling and Underground Space Association
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• v.12 no.1
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• pp.61-73
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• 2010

The cablebolt which secures a workability and stability has been used in foreign countries as one of supporting materials with rebar rockbolt especially in construction of large underground structures. However, only the rebar rockbolt has been applied up to now to all the constructions of underground structures in Korea due to an absence of recognition of cablebolt and large underground structure projects. Consequently, the research for a performance evaluation and verification of cablebolt is very limited and only the proto-type field tests have been conducted. In this study, the cone-shaped button cablebolt is developed by modifying an existing button cablebolt. To evaluate a performance and applicability of cone-shaped button cablebolt, the laboratory pull tests are conducted and bond capacity is analyzed under a various conditions. The rebar rockbolt, plane cablebolt, and bulb cablebolt which has a similar mechanical behavior with cone-shaped button cablebolt, are also tested and their bond capacities are evaluated and compared with cone-shaped button cablebolt under the same condition. The results show that the bond capacity is in the order of (cone-shaped button cablebolt$\approx$bulb cablebolt) > rockbolt > plane cablebolt. It is found that the bond capacity of cone-shaped button cablebolt developed in this study is at least equivalent with an existing high performance cablebolt developed in foreign countries, therefore the cone-shaped button cablebolt could be used as one of supporting materials for underground structures in construction field.

• Convergence Security Journal
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• v.22 no.1
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• pp.93-98
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• 2022

Information service technology continues to develop, and information service continues to expand based on the IT convergence trend. The premeter-based security model chosen by many organizations can increase the effectiveness of security technologies. However, in the premeter-based security model, it is very difficult to deny security threats that occur from within. To solve this problem, a zero trust model has been proposed. The zero trust model requires authentication for user and terminal environments, device security environment verification, and real-time monitoring and control functions. The operating environment of the information service may vary. Information security management should be able to response effectively when security threats occur in various systems at the same time. In this study, we proposed a security policy distribution system in the object reference method that can effectively distribute security policies to many systems. It was confirmed that the object reference type security policy distribution system proposed in this study can support all of the operating environments of the system constituting the information service. Since the policy distribution performance was confirmed to be similar to that of other security systems, it was verified that it was sufficiently effective. However, since this study assumed that the security threat target was predefined, additional research is needed on the identification method of the breach target for each security threat.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.1B
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• pp.11-20
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• 2008

The spillway type of small and midsize dams in Korea is almost overflow weir. To examine flood control capacity of overflow spillway, FLOW-3D was applied to Daesuho dam and analysis was focused on the discharge of dam spillway by changing weir shape. Overflow phases and discharges of linear labyrinth weir and curved labyrinth weir were compared with those of existing linear ogee weir. Hydraulic model experiment was performed to verify numerical result. Verification results showed that overflow behaviors and flow characteristics in the side channel by hydraulic model experiment and numerical simulation are well matched, and water surface elevation at side wall coincides with each other. When the reservoir elevation was increased up to design flood level, in case of the linear ogee weir the flow over the crest ran through smoothly in the side channel, whereas in cases of linear labyrinth weir and curved labyrinth weirs, the flow discharge was increased by 40 cms, and the flow over the weir crest, rotating counter-clockwise, was submerged in the side channel. The results of the water level-discharge curve revealed that labyrinth weir can increase discharge by 71% compared to the discharge of linear ogee weir at low reservoir elevation since it can have longer effective length. But as water surface elevation rises, the slope of water level-discharge curve of labyrinth weir becomes milder by submergence and nappe interference in the side channel.

• 한국노년학
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• v.29 no.1
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• pp.309-327
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• 2009

This research reviewed on the effect of elderly employment promotion project to their self-esteem and life satisfaction and got positive verification about the effectiveness of the project. The survey was conducted on 389 elderly people in Suncheon City. Some were participants on the project and others were not. SPSS Win 10.0 program was used for data analysis, and t-test, one-way ANOVA, correlation analysis, multiple regression were conducted. The results are as follows. First, elderly people who participated in the employment project had higher self-esteem and life satisfaction compare to those who did not participated in the project. Second, the job for elderly people had the most positive effect on elderly people to increase self-esteem and life satisfaction, and age, education background, income, family, and health were followed by. Third, participation on the employment for elderly was the highest correlation variable in self-esteem and life satisfaction, and health, education background, marriage status, residence type, living expense per month, economic status, and housing had significant correlations. Fourth, variables such as participation on job, education background, economic status, and age explained 32% of self-esteem, and 48% of life satisfaction. In order to increase self-esteem and life satisfaction of elderly people, we need to realize the importance of employment for elderly people, and promote projects that let elderly people to participate in job.

• Asia Marketing Journal
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• v.8 no.2
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• pp.1-26
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• 2006

In the growing field of green marketing there are various psychological influences that can lead to green purchase behavior. An understanding of these influences can lead to greater green marketing effectiveness. The purpose of this paper is to analyze the effects of several value types, environmental attitudes, and preference for product attributes on green purchase behavior. To this end, a conceptual model has been proposed and tested for empirical verification with the use of a survey. Data collected from 266 Korean respondents are analyzed using path analysis. Results provide support for the proposed model, demonstrating positive links among universalism, environmental attitudes, preference for environmental attribute, and green buying behavior. It indicates that individuals with universalism as a preferred value type are high in their environmental attitudes and finally, tend to buy green products through their preference for environmental attribute. The mediating role of preference for price is not significant between environmental attitudes and green purchase behavior. The present findings, in addition, contribute the width of understanding of various proenvironmental behaviors by focusing on green purchase behavior and surveying with a Korean sample. The implications for the practices of green marketing are discussed.

• Journal of the Korea Society of Computer and Information
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• v.28 no.10
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• pp.123-132
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• 2023

Git's commit messages manage the history of source changes during project progress or operation. By utilizing this historical data, project risks and project status can be identified, thereby reducing costs and improving time efficiency. A lot of research related to this is in progress, and among these research areas, there is research that classifies commit messages as a type of software maintenance. Among published studies, the maximum classification accuracy is reported to be 95%. In this paper, we began research with the purpose of utilizing solutions using the commit classification model, and conducted research to remove the limitation that the model with the highest accuracy among existing studies can only be applied to programs written in the JAVA language. To this end, we designed and implemented an additional step to standardize source change data into natural language using GPT. This text explains the process of extracting commit messages and source change data from Git, standardizing the source change data with GPT, and the learning process using the DistilBERT model. As a result of verification, an accuracy of 91% was measured. The proposed model was implemented and verified to ensure accuracy and to be able to classify without being dependent on a specific program. In the future, we plan to study a classification model using Bard and a management tool model helpful to the project using the proposed classification model.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.6
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• pp.138-143
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• 2023

In this study, the crack healing performance of each crack healing agent manufacturing method was analyzed by adding crack healing agents in the form of alginate gel and spore suspension inoculated with endospores of calcium carbonate-forming bacteria to mortar. In addition, by applying it to an full-scale structure in the form of a box-type culvert, we attempted to create an environment in which the developed crack healing agent can be applied not only to a laboratory environment but also to an actual field. The crack healing agent using the dry heat drying method showed crack healing performance, but in the case of the freeze drying method, many spores were killed by freeze hardening and therefore the crack healing performance was lost. As a result of SEM and XRD pattern analysis of the presumed crack healing material extracted from the crack of a full-scale structure, it was found to be calcite, one of the calcium carbonate crystals produced by microorganisms applied to the crack healing agent. In conclusion, it was found that the crack healing by microorganisms can be implemented in a real structure.

• Journal of Advanced Technology Convergence
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• v.2 no.4
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• pp.13-19
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• 2023

Following the signing of the Paris Agreement on Climate Change (UNFCCC, 2015), the world is expanding greenhouse gas reduction activities through comprehensive participation that includes not only developed countries but also developing countries. Major countries around the world are placing high expectations on the effectiveness of total carbon emissions regulation through the carbon emissions market. However, in order to obtain carbon credits, third-party verification is required based on quantitative carbon reduction data. Accordingly, in this paper, we developed an AIoT high-efficiency street light for carbon emissions and conducted a performance analysis study to measure the luminous efficiency of the lighting fixture. To obtain carbon emissions rights, we used high-efficiency LED PKG, developed our own high-voltage PFC, and developed high-efficiency lighting fixtures capable of communication. For communication, the 2.4GHz LoRa method was adopted between the lighting fixture and the gateway. Lens design was conducted through simulation of Korea Expressway Corporation's standard streetlight types A, B, and C. The performance of the streetlight was verified as being more efficient than other existing products through the measurement of luminous efficiency by an accredited rating agency, and it is expected that carbon emissions rights will be obtained by reducing electrical energy through this.