• Safety and Health at Work
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• v.13 no.2
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• pp.148-154
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• 2022

Background: Bus driving is a mentally demanding activity that requires prolonged attention to ensure safety. The aim of the study was to assess mental fatigue caused by driving a public bus and to find a profile of workers at higher risk. Methods: We evaluated changes of critical flicker fusion (CFF) (index of central arousal) and heart rate variability (HRV) (index of autonomic balance) in a 6-hour driving shift on a real route, in 31 professional bus drivers, and we tested the influence of personal factors such as sleep quality, BMI, and age. Paired t-test was used to test differences of CFF and HRV between both initial and final phase of driving, while multiple linear regression tested the influence of personal variables on the indexes of mental fatigue. Results: Results showed that CFF significantly decreased after 6 hours of bus driving (41.91 Hz, sd 3.31 vs. 41.15 Hz, sd 3.15; p = 0.041), and heart rate significantly decreased in the final phase of driving, with respect to the initial phase (85 vs. 78 bpm, p = 0.027). Increasing age (beta = -0.729, p = 0.022), risk of obstructive sleep apnea syndrome (beta = -0.530, p = 0.04), and diurnal sleepiness (beta = -0.406, p = 0.017) showed a significant effect on influencing mental fatigue. Conclusion: Elderly drivers at higher risk of sleep disorders are more prone to mental fatigue, when exposed to driving activity. Monitoring indexes of central arousal and autonomic balance, coupled with the use of structured questionnaires can represent a useful strategy to detect profile of workers at higher risk of mental fatigue in such duty.

• IEIE Transactions on Smart Processing and Computing
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• v.1 no.1
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• pp.50-64
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• 2012

Quality of Service (QoS) and fairness considerations are undoubtedly essential parameters that need to be considered in the design of next generation scheduling algorithms. This work presents a novel game theoretic cross-layer design that offers optimal allocation of wireless resources to heterogeneous services in Orthogonal Frequency Division Multiple Access (OFDMA) networks. The method is based on the Axioms of the Symmetric Nash Bargaining Solution (S-NBS) concept used in cooperative game theory that provides Pareto optimality and symmetrically fair resource distribution. The proposed strategies are determined via convex optimization based on a new solution methodology and by the transformation of the subcarrier indexes by means of time-sharing. Simulation comparisons to relevant schemes in the literature show that the proposed design can be successfully employed to typify ideal resource allocation for next-generation broadband wireless systems by providing enhanced performance in terms of queuing delay, fairness provisions, QoS support, and power consumption, as well as a comparable total throughput.

• Journal of Korea Spatial Information System Society
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• v.7 no.2 s.14
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• pp.81-89
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• 2005

Declustering and parallel index structures are important research areas to improve a performance of databases. Previous researches proposed several distribution schemes for parallel R-trees, however there is no search schemes to be suitable for the index. In this paper, we propose schemes to improve the performance of range queries for distribute parallel indexes. The proposed schemes use the features that a parallel disk can read multiple nodes from various disks. The proposed schemes are verified using various implementations and performance evaluations. We propose new schemes which can read multiple nodes from multiple disks in contrast that to the previous schemes which can read a node from disk. The experimental evaluation shows that the proposed schemes give us the performance improvement by 40% from the previous researches.

• Research in Community and Public Health Nursing
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• v.24 no.4
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• pp.480-487
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• 2013

Purpose: The purpose of this study was to investigate the relationship among family functioning, empathy and aggression by high school students. Methods: This was a descriptive study. The survey participants were 467 high school students from M city. Data were collected from November 29 to December 7, 2012 and self-report questionnaires including a Family Adaptability Cohesion Evaluation Scale, Interpersonal Reactivity Indexes, and an Aggression Questionnaire. The collected data were analyzed by descriptive statistics, independent-samples t-test, ANOVA, stepwise multiple regression. Results: The majority of the subjects were 2nd graders (42.0%) and female (57.2%). 59.7% of the subjects had religion, 84.8% were living together with parents. The mean ages of their fathers and mothers were $49.90{\pm}0.20$ and $46.85{\pm}0.19$ respectively. Aggression was found to have a statistically negative correlation with family functioning and empathy. Stepwise multiple regression analysis revealed that the most powerful predictor of aggression was empathic concern. Empathic concern, family cohesiveness, perspective taking, personal distress and gender accounted for 16.7% of the variances. Conclusion: It is necessary to provide aggressiveness reduction programs for high school students that consider their family functioning and empathy.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.10
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• pp.2252-2258
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• 2013

In this paper, parallel orthogonal matching pursuit (POMP) is proposed to supplement the simultaneous orthogonal matching pursuit (S-OMP) which has been widely used as a greedy algorithm for sparse signal recovery for multiple measurement vector (MMV) problem. The process of POMP is simple but effective: (1) multiple indexes maximally correlated with the observation vector are chosen at the first iteration, (2) the conventional S-OMP process is carried out in parallel for each selected index, (3) the index set which yields the minimum residual is selected for reconstructing the original sparse signal. Empirical simulations show that POMP for MMV outperforms than the conventional S-OMP both in terms of exact recovery ratio (ERR) and mean-squared error (MSE).

• Korean Journal of Community Nutrition
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• v.18 no.4
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• pp.312-323
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• 2013

Variables affecting bone heath of growing children were analyzed among forty nine 10-12 year old elementary students in three rural regions of north west Chungnam area. Information on age of the parents, duration of breast feeding and birth weight were collected from the guardians of the participants and nutrient intake and diet quality were assessed by average of three-day food records of participants with the help of dietitians. Bone health status was measured by calceneal broadband ultrasound attenuation (BUA) using quantitative ultrasound (QUS). Results showed that anthropometic indexes and nutrient intake levels were not different between boys and girls. However, iron intake was significantly lower in girls than in boys. Girls after menarche showed lower intake levels for thiamin, riboflavin, pyridoxine and niacin than girls before menarche. z-scores of BMI were lower than -1 and higher than +1 showed shorter breast feeding period than others but the difference was statistically non-significant. Overall, the subjects did not consume enough s of calcium, vitamin C and folic acid. Zinc intake and BMI were the most significant factors affecting BUA by the results of backward elimination in multiple regression models. Phosphorous and beta-carotene intakes showed significant negative relation with BUA. This study showed that children living in the rural area of Chungnam need extra care to keep their health and nutrient intakes especially for the nutrients known to affect growth. Tailored nutrition education needs to be more focused on the improvement of bone health status of children.

• The Korean Journal of Physiology and Pharmacology
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• v.20 no.6
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• pp.565-571
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• 2016

Paeoniflorin (PAE) is the most abundant compound in Xuebijing injection widely used to treat sepsis. We aimed to investigate effect of PAE on expression of soluble triggering receptor expressed on myeloid cells-1 (sTREM-1) in a rat model of sepsis. Wistar rats were divided into Normal, Model, and PAE groups (n=20 each). Endotoxin was administrated at 5 mg/ml/kg in Model and PAE rats to establish rat sepsis model. 1 h after endotoxin administration, PAE was administrated at 4 ml/kg in PAE group once per day for 3 days. Routine blood tests and biochemical indexes were assessed, including aspartate aminotransferase (AST) and creatine kinase-MB (CK-MB). The plasma sTREM-1 level was measured using quantitative ELISA. At the end of experiment, the small intestine, liver, kidney and lung were subjected to pathological examinations. A rat model of sepsis-induced multiple organ dysfunction syndrome (MODS) was established successfully with endotoxin administration (5 mg/ml/kg), evidenced by histo-pathological examinations, routine blood tests and biochemical indexes: platelet count decreased and white blood cell count increased (p<0.05), CK-MB and AST increased (p<0.05). PAE treatment significantly reduced the plasma levels of AST, CK-MB, and sTREM-1, compared to Model group (p<0.05). Meanwhile, sepsis-induced damages in the liver, lung, stomach and intestinal mucosa were also markedly ameliorated by PAE treatment. PAE demonstrated a significantly protective effect in a rat model of sepsis by decreasing plasma sTREM-1 level, reducing inflammation, preventing MODS and protecting organ functions.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.447-452
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• 2012

Among the various elements affecting a customer's evaluation of automobile quality, buzz, squeak and rattle (BSR) are considered to be major factors. In most vehicle manufacturers, the BSR problems are solved by find-fix method with the vehicle road test, mainly due to various excitation sources, complex generation mechanism and subjective response. The aim of this paper is to develop the integrated experimental method to systematically tackle the BSR problems in early stage of the vehicle development cycle by resolving these difficulties. To achieve this aim, the developed experimental method ought to include the following requirements: to find and fix the BSR problem for modules instead of a full vehicle in order to tackle the problem in the early stage of the vehicle development cycle; to develop the exciter system including the zig and road-input-signal reproducing algorithm; to automatically localize the source region of BSR; to develop sound quality index that can be used to assess the subjective responses to BSR. Also, the BSR sound quality indexes based on the Zwicker's sound quality parameters using a multiple regression analysis. The four sound metrics from Zwicker's sound quality parameter are computed for the signals recorded for eight BSR noise source regions localized by using the acoustic-field visualized results. Then, the jury test of BSR noise are performed for participants. On a basis of the computed sound metrics and jury test result, sound quality index is developed to represent the harsh of BSR noise. It is expected that the developed BSR detection system and sound quality indexes can be used to reduce the automotive interior BSR noise in terms of subjective levels as well as objective levels.

• The Journal of Society for e-Business Studies
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• v.22 no.4
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• pp.117-128
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• 2017

The increased national utilization of Bitcoin results in multiple complications. Therefore, there are continuous debates on the subject, the main point being how to characterize Bitcoin's asset nature. The following study bases, focusing on the function value, justifies Bitcoin's asset characterization. Using regression analysis to construct relations between gold and indexes such as CPI, DXY, and S&P500 as well as the relation between Bitcoin and the previously mentioned indexes, the question of whether gold and Bitcoin reacted in a similar fashion to the same indicators was examined. The results conclude that Bitcoin has similarities with gold, showing that it is risk averse and an investable commodity in lieu to profitability when it comes to inflation and currency value. When considered with price volatility, the main force behind the function of investment asset, categorizing Bitcoin as a high-risk financial investment asset rather than as a currency within the system would be more effective for management.

• Journal of the Korean Society for information Management
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• v.31 no.4
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• pp.49-68
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• 2014

The purpose of this study is to perform content analysis of research articles using the language network analysis method in Korea and catch the basic point of the language network analysis method. Six analytical categories are used for content analysis: types of language text, methods of keyword selection, methods of forming co-occurrence relation, methods of constructing network, network analytic tools and indexes. From the results of content analysis, this study found out various features as follows. The major types of language text are research articles and interview texts. The keywords were selected from words which are extracted from text content. To form co-occurrence relation between keywords, there use the co-occurrence count. The constructed networks are multiple-type networks rather than single-type ones. The network analytic tools such as NetMiner, UCINET/NetDraw, NodeXL, Pajek are used. The major analytic indexes are including density, centralities, sub-networks, etc. These features can be used to form the basis of the language network analysis method.