• Journal of the Korea Institute of Information Security & Cryptology
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• v.20 no.5
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• pp.23-36
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• 2010

Signcryption is a cryptographic primitive which offers authentication and confidentiality simultaneously with a cost lower than signing and encrypting the message independently. We propose a new cryptographic notion called Identity-based online/offline signcryption. The notion of online/offline scheme can be divided into two phases, the first phase is performed offline prior to the arrival of a message to be signed or encrypted and the second phase is performed online phase after knowing the message and the public key of recipient. The Online phase does not require any heavy computations such as pairings or exponents. It is particularly suitable for power-constrained devices such as smart cards. In this paper, we propose ID-based signcryption scheme and ID-based online/offline signcryption scheme where the confidentiality and authenticity are simultaneously required to enable a secure and trustable communication environment. To our best knowledge, this is the first ID-based online/offline signcryption scheme that can be proven secure in the standard model.

• Knowledge Management Research
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• v.22 no.2
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• pp.19-32
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• 2021

Bitcoin, a representative cryptocurrency, is receiving a lot of attention around the world, and the price of Bitcoin shows high volatility. High volatility is a risk factor for investors and causes social problems caused by reckless investment. Since the price of Bitcoin responds quickly to changes in the world environment, we propose to predict the price volatility of Bitcoin by utilizing news information that provides a variety of information in real-time. In other words, positive news stimulates investor sentiment and negative news weakens investor sentiment. Therefore, in this study, sentiment information of news and deep learning were applied to predict the change in Bitcoin yield. A single predictive model of logit, artificial neural network, SVM, and LSTM was built, and an integrated model was proposed as a method to improve predictive performance. As a result of comparing the performance of the prediction model built on the historical price information and the prediction model reflecting the sentiment information of the news, it was found that the integrated model based on the sentiment information of the news was the best. This study will be able to prevent reckless investment and provide useful information to investors to make wise investments through a predictive model.

• The Journal of the Korea Contents Association
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• v.21 no.6
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• pp.1-11
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• 2021

The Neis System is a system integrating administrative information that was operated in elementary and secondary schools in Korea. Currently, this system is operated by a central server method and contains school administration information and important educational information of students. Among student information, the student life record contains important information for a student to advance to a higher level institution, but problems such as information leakage or manipulation may occur due to malicious attacks. In this paper, we propose a hybrid blockchain system that combines the server and blockchain technology managed by the existing Neis system. The proposed system records the query information of the database in a block when student information is accessed. When a request for correction of student information or issuance of a certificate is received, the query of the blockchain, the information in the database, and the student's key value are checked to determine whether the information has been leaked or manipulated, and only if the data is normal, the request for revision of the record is performed. This process is more secure than the existing central server because it checks the manipulation of data through the blockchain. The proposed system was implemented on the Ethereum platform, and the query information of the blockchain was experimentally verified using smart contracts. This study contributes to enhancing the reliability of the Nice system by strengthening the security against forgery and alteration of student data by combining the existing Nice system with a block chain.

• Journal of Digital Convergence
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• v.19 no.6
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• pp.175-184
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• 2021

The purpose of this study is to investigate the effect of the strategic role of the human resources department in the manufacturing industry on organizational effectiveness through education and training satisfaction. Among the data from the 7th human capital company panel survey, data from the manufacturing industry were used and analyzed through a structural equation model. The results of this study are as follows: First, the strategic role of the HR department has a positive effect on satisfaction with education and training. Second, satisfaction with education and training and the strategic role of HR departments have a positive effect on job satisfaction among organizational effectiveness. Third, it was confirmed that education and training satisfaction has a mediating effect on the relationship between the HR department's strategic role and job satisfaction. The results of this study are expected to become the basis for expanding the authority and responsibilities of the HR department, which is an important factor in overcoming the crisis faced by SMEs as well as innovation, and redefining their role.

• Environmental and Resource Economics Review
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• v.30 no.2
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• pp.237-268
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• 2021

As variable renewable sources rapidly increase due to the Energy Transition plan, integration cost of renewable sources to the power system is rising sharply. The increase in variable renewable energy reduces the capacity factor of existing traditional power capacity, and this undermines the efficiency of the overall power supply, and demand resources are drawing attention as a solution. In this study, we analyzed how much electric vehicle demand resouces, which has great potential among other demand resources, can reduce power supply costs if it is used as a flexible resource for renewable generation. As a methodology, a stochastic form of power system optimization model that can effectively reflect the volatile characteristics of renewable generation is used to analyze the cost induced by renewable energy and the benefits offered by electric vehicle demand resources. The result shows that virtual power plant-based direct control method has higher benefits than the time-of-use tariff, and the higher the proportion of renewable energy is in the power system, the higher the benefits of electric vehicle demand resources are. The net benefit after considering commission fee for aggregators and battery wear-and-tear costs was estimated as 67% to 85% of monthly average fuel cost under virtual power plant with V2G capability, and this shows that a sufficient incentive for market participation can be offered when a rate system is applied in which these net benefits of demand resources are effectively distributed to consumers.

• Journal of the Korean Applied Science and Technology
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• v.38 no.3
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• pp.870-882
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• 2021

Coptis chinensis has been used in the treatment of various diseases such as soothing, anti-inflammation, antimicrobial and antipyretic in oriental traditional medicine. In this study, we investigated the effect of hot water extract of Coptis chinensis(CCW) on skin barrier and inflammation-related factors in UVB and TNF-α/IFN-γ-induced HaCaT cells and evaluated its potential as a moisturizing and anti-inflammatory material. Based on result, the amount of HA (Hyaluronic acid) production and protein and mRNA expression of filaggrin were measured. In TNF-α/IFN-γ-induced HaCaT cells, CCW increased the amount of HA production in a concentration-dependent manner. In the measurement of protein and mRNA expression of filaggrin, the expression rate increased as the concentration of CCW increased. In UVB-induced HaCaT cells, CCW decreased the production of ROS and showed significant results with EGCG ((-)-epigallocatechin-3-gallate), a positive control. In addition, CCW inhibited the expression of inflammatory cytokines TNF-α, IL-1β, IL-6, and IL-8 in TNF-α/IFN-γ-induced HaCaT cells. It was confirmed that the protein and mRNA expression of COX-2, a major factor in skin inflammation, was decreased in a concentration-dependent manner. These results suggest that hot water extract from Coptis chinensis can be used as a cosmetic material having a moisturizing and anti-inflammatory effect.

• Journal of Drive and Control
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• v.17 no.4
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• pp.133-140
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• 2020

Traction performance of a tractor varies depending on soil conditions. Sinkage and slip of the driving wheel for tractor frequently occur in a reclaimed land. The objective of this study was to develop a tractor suitable for a reclaimed land. Traction performance was evaluated according to soil conditions of reclaimed land and paddy field. Field experiments were conducted at two test sites (Fields A: paddy field; and Field B: reclaimed land). The tractor load measurement system was composed of an axle rotation speed sensor, a torque meter, a six-component load cell, GPS, and a DAQ (Data Acquisition System). Soil properties including soil texture, water content, cone index, and electrical conductivity (EC) were measured. Referring to previous researches, the tractor traveling speed was set to B3 (7.05 km/h), which was frequently used in ridge plow tillage. Soil moisture contents were 33.2% and 48.6% in fields A and B, respectively. Cone index was 2.1 times higher in field A than in field B. When working in the reclaimed land, slip ratios were about 10.5% and 33.1% for fields A and B, respectively. The engine load was used almost 100% of all tractors under the two field conditions. Traction powers were 31.9 kW and 24.2 kW for fields A and B, respectively. Tractive efficiencies were 83.3% and 54.4% for fields A and B, respectively. As soil moisture increased by 16.4%, the tractive efficiency was lowered by about 28.9%. Traction performance of tractor was significantly different according to soil conditions of fields A and B. Therefore, it is necessary to improve the traction performance of tractor for smooth operations in all soil conditions including a reclaimed land by reflecting data of this study.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.2
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• pp.127-133
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• 2021

A recent study of people physically falling focused on analyzing the motions of the falls using a recurrent neural network (RNN) and a deep learning approach to get good results from detecting 2D human poses from a single color image. In this paper, we investigate a detection method for estimating the position of the head and shoulder keypoints and the acceleration of positional change using the skeletal keypoints information extracted using PoseNet from an image obtained with a low-cost 2D RGB camera, increasing the accuracy of judgments about the falls. In particular, we propose a fall detection method based on the characteristics of post-fall posture in the fall motion-analysis method. A public data set was used to extract human skeletal features, and as a result of an experiment to find a feature extraction method that can achieve high classification accuracy, the proposed method showed a 99.8% success rate in detecting falls more effectively than a conventional, primitive skeletal data-use method.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.845-856
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• 2020

This study proposes a bridge evaluation system for indivisible permit vehicles such as hydraulic cranes. The permit loads for the bridge evaluation are divided into three categories: routine permit loads, special permit 1 loads, and special permit 2 loads. Routine permit and special permit 1 vehicles are allowed to cross a bridge with normal traffic. For these two permits, the standard lane model in the Korean Highway Bridge Design Code was adopted to consider normal traffic in the same lane. Special permit 2 vehicles are assumed to cross a bridge without other traffic. Structural analyses of two prestressed-beam bridges and two steel box girder bridges were conducted for the proposed permit loads. The rating factors of the four bridges for all permit loads were calculated as sufficiently large values for the moment and shear force so that crossing the bridges can be permitted. A reliability assessment of the bridges was performed to identify the reliability levels for the permit vehicles. It was confirmed that the reliability level of the minimum required strength obtained by the load-resistance factors yields the target reliability index of the design code for the permit vehicles.

• Journal of the Korean Applied Science and Technology
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• v.37 no.6
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• pp.1496-1506
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• 2020

This study was conducted as follows in order to find out the possibility of using (Chamaecyparis obtusa) by part as a cosmetic material. Chamaecyparis obtusa was separated leaves, bark, wood, and root, and extracted with 99.9% ethanol, and the antioxidant and whitening effects of the sample were confirmed. For this, the following studies were conducted. Antioxidant evaluation was confirmed by 1 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, 2 2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS+) radical scavenging activity. To evaluate the whitening effect, mushroom tyrosinase inhibitory activity evaluation and cytotoxicity evaluation of Chamaecyparis obtusa extract through MTT assay were conducted, and cellular tyrosinase inhibition rate was measured and melanin contents was confirmed. As a result of antioxidant activity, Bark extract among Chamaecyparis obtusa parts showed the best efficacy, and bark in B16F10 melanoma cell showed tyrosinase activity inhibition and melanin contents inhibitory effects. Therefore, it was confirmed that the ethanol extract of Chamaecyparis obtusa was developed as a natural material for safe and excellent whitening functional cosmetics.