• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.4
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• pp.87-92
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• 2019

In this paper, a closed hydroponics device was designed and fabricated to grow and harvest plants in a small space for safe consumption, which enables horticultural activities that are difficult to perform due to space constraints from urbanization. This device also aimed to minimize the air pollution of crops. To obtain data for the optimal growth conditions for crops in this intelligent plant-growing system, sensors were used to measure and control the growth conditions. To investigate the optimal growth conditions, blue lettuce and crown daisy were selected as representative crops. The growth rates were comparatively analyzed through four experiments for each plant. This hydroponics device was used to collect data on growth rates that are altered depending on cultivation conditions, which can then be used to study methods to control the growth rate of crops.

• International Journal of Advanced Culture Technology
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• v.10 no.1
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• pp.294-301
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• 2022

COVID-19 is a crisis with numerous casualties. The World Health Organization (WHO) has declared the use of masks as an essential safety measure during the COVID-19 pandemic. Therefore, whether or not to wear a mask is an important issue when entering and exiting public places and institutions. However, this makes face recognition a very difficult task because certain parts of the face are hidden. As a result, face identification and identity verification in the access system became difficult. In this paper, we propose a system that can detect masked face using transfer learning of Yolov5s and recognize the user using transfer learning of Facenet. Transfer learning preforms by changing the learning rate, epoch, and batch size, their results are evaluated, and the best model is selected as representative model. It has been confirmed that the proposed model is good at detecting masked face and masked face recognition.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.11 s.254
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• pp.1335-1347
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• 2006

Surface energies calculated from measured contact angles between several solutions and test samples, such as Si wafer, $Al_2O_3$, $SiO_2$, PTFE(Polytertrafluoroethylene), and DLC(Diamond Like Carbon) films, based on geometric mean method and Lewis acid base method. In order to relate roughness to adhesion force, surface roughness of test samples were scanned large area and small by AFM(Atomic Force Microscopy). Roughness was representative of test samples in large scan area and comparable with AFM tip radius in small scan area. Adhesion forces between AFM tip and test samples were matched well with order of roughness rather then surface energy. When AFM tips having different radius were used to measure adhesion force on DLCI film, sharper AFM tip was, smaller adhesion force was measured. Therefore contact area was more important factor to determine adhesion force.

• Journal of Korean Library and Information Science Society
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• v.27
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• pp.369-389
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• 1997

KDC(Korea Decimal Classification), which is representative literature classification scheme in Korea, was revised and published in 1996. The purpose of this paper is to suggest a reform measure after detecting out issues and problems associated with the KDC 4th ed. through the result of lecture. The outline of suggestions are as follows : (1) There are not all items of auxiliary tables in relative index. (2) Auxiliary table 2 (Geographic Areas) is not detailed. (3) The manual for the shake of efficient usage is nonexistent and notes are poor in content. (4) Sufficient minimax and alternatives must be setted up for efficiency usage. (5) Some parts of the main schedule are disorder and not logical.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1169-1175
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• 2008

The validation technique is classified with two methods whether to demand of additional experimental points. The method which requires additional experimental points such as RSME is actually impossible in engineering field. Therefore, the method which only use experimented points such as the cross validation technique is only available. But the cross validation not only requires considerable computational costs for generating metamodel each iterations, but also cannot measure quantitatively the fidelity of metamodel. In this research we propose a new validation technique for representative metamodels using an variance of metamodel and confidence interval information. The proposed validation technique computes confidence intervals using a variance information from the metamodel. This technique will have influence on choosing the accurate metamodel, constructing ensemble of each metamodels and advancing effectively sequential sampling technique.

• The Journal of Information Technology and Database
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• v.4 no.2
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• pp.33-45
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• 1998

Database summarization is the procedure to obtain generalized and representative descriptions expressing the content of a large amount of database at a glance. We present a top-down summary refinement procedure to discover database summaries. The procedure exploits attribute concept hierarchies that represent ISA relationships among domain concepts. It begins with the most generalized summary and proceeds to find more specialized ones by stepwise refinements. This top-down paradigm reveals at least two important advantages compared to the previous bottom-up methods. Firstly, it provides a natural way of reflecting the user's own discovery preference interactively. Secondly, it does not produce too large intermediate result that makes it hard for the bottom-up approach to be applied in practical environment. The proposed procedure can also be easily extended for distributed databases. Information content measure of a database summary is derived in order to identify more informative summaries among the discovered results.

• Journal of Korea Society of Digital Industry and Information Management
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• v.19 no.3
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• pp.25-38
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• 2023

Instrumentation and control systems measure and control various variables of nuclear facilities to operate nuclear power plants safely. A diverse protection system, a representative instrumentation and control system, generates a reactor trip and turbine trip signal by high pressure in a pressurizer and containment to satisfy the design requirements 10CFR50.62. Also, it generates an auxiliary feedwater actuation signal by low water levels in steam generators. Cybersecurity has become more critical as digital technology is gradually applied to solve problems such as performance degradation due to aging of analog equipment, increased maintenance costs, and product discontinuation. This paper analyzed possible cybersecurity threat scenarios in the diverse protection system using attack trees. Based on the analyzed cybersecurity threat scenario, we calculated the probability of attack occurrence and confirmed the cybersecurity risk in connection with the asset value.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.15 no.3
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• pp.166-171
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• 2015

In this paper, we measure the current and vibration signals of one-dimensional time series that occur in a motor and pump, respectively. These machines are representative rotary and pumping machines. We also eliminate unnecessary components such as noise by pre-processing the current and vibration signals. Then, in order to diagnose fault signals for the pump and motor, we transform from one-dimensional time series to a two-dimensional phase portrait using Takens’ embedding method. After this transformation, we review the variation in the pattern according to the fault signals.

• Nuclear Engineering and Technology
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• v.51 no.3
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• pp.683-691
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• 2019

In this paper, we propose a novel method to quantify the neural synchronization between subjects in the collaborative process through electroencephalogram (EEG) hyperscanning. We hypothesized that the neural synchronization in EEGs will increase when the communication of the operators is smooth and the teamwork is better. We quantified the EEG signal for multiple subjects using a representative EEG quantification method, and studied the changes in brain activity occurring during collaboration. The proposed method quantifies neural synchronization between subjects through bispectral analysis. We found that phase synchronization between EEGs of multi subjects increased significantly during the periods of collaborative work. Traditional methods for a human error analysis used a retrospective analysis, and most of them were analyzed for an unspecified majority. However, the proposed method is able to perform the real-time monitoring of human error and can directly analyze and evaluate specific groups.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.05a
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• pp.655-656
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• 2022

Among the analysis methods for a recommendation system, collaborative filtering is a major representative method in a recommendation system based on data analysis. A general usage method is a technique of finding a common pattern by using evaluation data of users for various items, and recommending a preferred item for a specific user. Therefore, in this paper, various algorithms were used to measure the index, and an algorithm suitable for prediction of user preference was found and presented.