• Journal of Astronomy and Space Sciences
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• v.32 no.3
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• pp.181-187
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• 2015

Storm sudden commencements (SSCs) occur due to a rapid compression of the Earth's magnetic field. This is generally believed to be caused by interplanetary (IP) shocks, but with exceptions. In this paper we explore possible causes of SSCs other than IP shocks through a statistical study of geomagnetic storms using SYM-H data provided by the World Data Center for Geomagnetism - Kyoto and by applying a superposed epoch analysis to simultaneous solar wind parameters obtained with the Advanced Composition Explorer (ACE) satellite. We select a total of 274 geomagnetic storms with minimum SYM-H of less than -30nT during 1998-2008 and regard them as SSCs if SYM-H increases by more than 10 nT over 10 minutes. Under this criterion, we found 103 geomagnetic storms with both SSC and IP shocks and 28 storms with SSC not associated with IP shocks. Storms in the former group share the property that the strength of the interplanetary magnetic field (IMF), proton density and proton velocity increase together with SYM-H, implying the action of IP shocks. During the storms in the latter group, only the proton density rises with SYM-H. We find that the density increase is associated with either high speed streams (HSSs) or interplanetary coronal mass ejections (ICMEs), and suggest that HSSs and ICMEs may be alternative contributors to SSCs.

• Industrial Engineering and Management Systems
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• v.14 no.4
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• pp.335-346
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• 2015

The electronic commerce site (EC site) has become an important marketing channel where consumers can purchase many kinds of products; their access logs, including purchase records and browsing histories, are saved in the EC sites' databases. These log data can be utilized for the purpose of web marketing. The customers who purchase many product items are good customers, whereas the other customers, who do not purchase many items, must not be good customers even if they browse many items. If the attributes of good customers and those of other customers are clarified, such information is valuable as input for making a new marketing strategy. Regarding the product items, the characteristics of good items that are bought by many users are valuable information. It is necessary to construct a method to efficiently analyze such characteristics. This paper proposes a new latent class model to analyze both purchasing and browsing histories to make latent item and user clusters. By applying the proposal, an example of data analysis on an EC site is demonstrated. Through the clusters obtained by the proposed latent class model and the classification rule by the decision tree model, new findings are extracted from the data of purchasing and browsing histories.

• Biomedical Science Letters
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• v.18 no.1
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• pp.22-28
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• 2012

The purpose of this study was to investigate the effect of soybean peptide on antioxidant enzymes, cortisol hormone and inflammatory cytokine levels. 19 high school male judo athletes participated in the experiments. They were randomly divided into two groups, one group took soybean peptide (S-peptide, n=10) 4 g a day for 4 weeks and the other group placebo (placebo group, n=9) for the same time. Blood samples were collected before intake, after 2 weeks intake and 4 weeks intake and these were analyzed for total antioxidant status (TAS), catalase (CAT), levels of cortisol hormone, tumor necrosis factor-alpha (TNF-${\alpha}$) and interleukin-6 (IL-6). As a result, the S-peptide group was significantly increased in TAS and CAT (P<0.05). The malondialdehyde (MDA) levels showed decrease after soybean peptide intake but there was no significant difference. In the levels of plasma cortisol which reflect stress status, there was significantly decreased in the S-peptide and placebo group after 4 weeks (P<0.05). There were significant decreases of TNF-${\alpha}$ and IL-6 after 4 weeks in S-peptide group (P<0.05). These results suggest that the intake of soybean peptide can activate antioxidant defenses and decrease exercise-induced oxidative stress.

• Journal of Convergence for Information Technology
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• v.10 no.8
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• pp.108-119
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• 2020

This describes the level of knowledge and attitudes about HIV and their related factors among Cambodian adolescents. A cross-sectional design was used to examine the knowledge and attitude of 463 Cambodian high school students using HIV-KQ-18 (HIV-Knowledge Questionnaire-18) and HIV/AIDS Behavior Surveillance Survey Index (measuring attitude about HIV). The majority of the adolescents had a relatively low level of overall HIV knowledge (6.70 ± 3.66 (range: 0-16)) and held a very negative attitude (1.92 ± 0.87 points (range: 0-4)) toward the disease. Using multiple regression analysis, being male (β = 0.28, p < 0.001) and using YouTube as a social network service (β = 0.33, p = 0.035) were found to be independent factors associated with higher level of HIV knowledge. Study findings suggest the importance of informing policymakers and school nurses about the need to develop a and require a culturally sensitive specific health education program on HIV for Cambodian adolescents.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.46 no.5
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• pp.71-78
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• 2009

In RFID system, the communicated data can be easily eavesdropped and tampered with by an attacker because the communication between the reader and the tag is performed in an insecure channel. Therefore, authentication is an important role in RFID applications for providing security and privacy. In 2006, Lee, Asano and Kim proposed an RFID mutual authentication protocol (the LAK protocol) which utilizes a hash function and synchronized secret information. However, Cao and Shen showed that the LAK protocol is vulnerable to replay attack, and therefore an adversary can impersonate the tag. This paper proposes a new simple two-round RFID mutual authentication (TRMA) protocol based on secure one-way hash function. As a result, the proposed TRMA protocol not only can prevent various attacks and but also provides communication efficiency since they mutually authenticate by performing two-round between RFID tag and RFID reader.

• Transactions of the KSME C: Technology and Education
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• v.5 no.2
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• pp.97-104
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• 2017

In this study, we verify the accurate numerical analysis and simplify the perforated plate of inlet and exhaust duct using porous media for the cost reduction and the efficiency improvement of thermal-fluid analysis to evaluate cooling performance of wheel-loader. The flow loss coefficient of the perforated plate is defined by the experiment result. To define analytically the flow loss coefficient of the perforated plate, we calculate the pressure drop of unit-cell and compare to experiment result. Finally, we compare the heat balance test and the simplified simulation result on the inlet and exhaust duct of wheel-loader. After this study, we verify the applicability of the simplified analysis method on the inlet and exhaust duct of wheel-loader. And, foundation which can carry out effectively the evaluation and improvement for cooling performance of wheel-loader is prepared.

• Journal of Convergence for Information Technology
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• v.9 no.11
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• pp.202-211
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• 2019

This study was conducted to identify the correlation between smartphone addiction, sleep quality, and depression in college students. The participants were 304 college students in G area. Data were collected using self-report questionnaires and data were analyzed by frequency, percent, mean, standard deviation, t-test, One way ANOVA and Pearson correlation coefficient. The results showed that there was a significant negative correlation between smartphone addiction and sleep quality, a significant positive correlation between smart addiction and depression, and a significant negative correlation between sleep quality and depression. Therefore, the results of this study can be used as a useful basic data when looking for education and program development strategies to improve and prevent smartphone addiction, sleep quality, and depression of college students. In addition, it is required to apply a systematic educational program considering this.

• Journal of the Korea Society of Computer and Information
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• v.25 no.6
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• pp.225-230
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• 2020

The purpose of this study was to present implications for empirical analysis of the structural relationship between the level of activities for senior citizens, self-efficacy, and life satisfaction and depression. In order to the survey was conducted For the elderly students who are enrolled in the Senior Citizens' Welfare Center and participating in the information service education in the G-metropolitan city. The method of data analysis was verified by the Regression and Hierarchical Regression analysis using the spss 22.0 statistical program. As a result, The level of activity for the elderly increases the level of self-efficac, The level of activity and self-efficacy of the elderly increased the level of living satisfaction of the elderly and It has been shown to lower the level of depression. Self-efficacy has been shown to have a mediating effect in the relationship between senior citizens' level of information service activities and living satisfaction and depression. Based on these analysis results, a policy measure was proposed to enhance the level of activities for senior citizens.

• Geomechanics and Engineering
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• v.16 no.6
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• pp.643-654
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• 2018

Tunnel excavation leads to a disturbance on the initial stress balance of surrounding soils, which causes convergences around the tunnel and settlements at the ground surface. Considering the effective impact of settlements on the structures at the surface, it is necessary to estimate them, especially in urban areas. In the present study, ground settlements due to the excavation of East-West Line 7 of the Tehran Metro (EWL7) and the Abuzar tunnels are evaluated and the effect of the lateral earth pressure coefficient ($K_0$) on their extension is investigated. The excavation of the tunnels was performed by TBMs (Tunnel Boring Machines). The coefficient of lateral earth pressure ($K_0$) is one of the most important geotechnical parameters for tunnel design and is greatly influenced by the geological characteristics of the surrounding soil mass along the tunnel route. The real (in-situ) settlements of the ground surface were measured experimentally using leveling methods along the studied tunnels and the results were compared with evaluated settlements obtained from both semi-empirical and numerical methods (using the finite difference software FLAC3D). The comparisons permitted to show that the adopted numerical models can effectively be used to predict settlements induced by a tunnel excavation. Then a numerical parametric study was conducted to show the influence of the $K_0$ values on the ground settlements. Numerical investigations also showed that the shapes of settlement trough of the studied tunnels, in a transverse section, are not similar because of their different diameters and depths of the tunnels.

• Journal of Convergence for Information Technology
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• v.9 no.3
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• pp.90-97
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• 2019

In order to identify relationships between oral health management behavior and subjective oral health perception and oral acid production in small and medium industry workers, an examination on oral acid production and a survey were conducted. As a result, the subjective oral health status, which is subjective oral health perception, was found to have a significant effect on oral acid production, and the worse the subjective oral health status was, the higher the oral acid production was. As the subjective oral health perception is expected to be helpful for the development of industrial oral health programs to improve oral health of workers, organizational and institutional efforts for industrial oral health education will be necessary for improvement of subjective oral health perception of workers.