• Journal of Korean Society of Industrial and Systems Engineering
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• v.21 no.47
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• pp.57-68
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• 1998

Work environments have been changed with the advent of new technologies, such as computer technology. However, human cognitive limits can't pace up with the change of work environment. Designing human-computer system requires knowledge and evaluation of the human cognitive processes which control information flow workload. Futhermore, under limited reaction time and/or urgent situation, human operator may the work stress, work error and resultant deleterious work environment. This paper evaluate the visual factors of major information processing factors(information density, amount of information, operational speed of speed)on operator performance of supervisory control under urgent(limited reaction time)environments which require deleterious work condition. To describe the work performance int the urgent work situations with time stress and dynamic event occurrence, a new concept of information density was introduced. For a series of experiments performed for this study, three independent variables(information amount, system proceeding speed, information density) were evaluated using five dependent variables. The result of statistical analyses indicate that the amount of information affected on all of five dependent measure. Number of failure and number of secondary task score were influenced by both amount of information and operational speed of system. However reaction time of secondary task were affected by both amount of information and information density. As a result, the deleterious factors for the performances seemed to be a scanning time to supervise each control panel. Consequently, a new display panel was suggest to reduce operator work load for scanning task showing better operator performance.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.9
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• pp.3126-3145
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• 2014

Cloud computing is a computing paradigm in which users can rent computing resources from service providers according to their requirements. A spot instance in cloud computing helps a user to obtain resources at a lower cost. However, a crucial weakness of spot instances is that the resources can be unreliable anytime due to the fluctuation of instance prices, resulting in increasing the failure time of users' job. In this paper, we propose a Genetic Algorithm (GA)-based workflow scheduling scheme that can find the optimal task size of each instance in a spot instance-based cloud computing environment without increasing users' budgets. Our scheme reduces total task execution time even if an out-of-bid situation occurs in an instance. The simulation results, based on a before-and-after GA comparison, reveal that our scheme achieves performance improvements in terms of reducing the task execution time on average by 7.06%. Additionally, the cost in our scheme is similar to that when GA is not applied. Therefore, our scheme can achieve better performance than the existing scheme, by optimizing the task size allocated to each available instance throughout the evolutionary process of GA.

• Journal of Institute of Control, Robotics and Systems
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• v.5 no.5
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• pp.614-621
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• 1999

In this paper, the analytical appproaches are presented for jointly determining the profit-miximizing configuration of the fault-tolerance real time modular cell manufacturing system. The transient(time-dependent) analysis of Markovian models is firstly applied to modular cell manufacturing system from a performability viewpoint whose modeling advantage lies in its ability to express the performance that truly matters - the user's perception of it - as well as various performance measures compositely in the context of application. The modular cells are modeled with hybrid decomposition method and then availability measures such as instantaneous availability, interval availability, expected cumulative operational time are evaluated as special cases of performability. In addition to this evaluation, sensitivity analysis of the entire manufacturing system as well as each machining cell is performed, from which the time of a major repair policy and the optimal configuration among the alternative configurations of the system can be determined. Secondly, the recovery policies from the machine failures by computing the minimal number of redundant machines and also from the task failures by computing the minimum number of tasks equipped with detection schemes of task failure and reworked upon failure detection, to meet the timing requirements are optimized. Some numerical examples are presented to demonstrate the effectiveness of the work.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.17 no.32
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• pp.243-253
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• 1994

Work environments have been changed with the advent of new technologies, such as computer technology. The newer technologies, the more changes in our work conditions. However, human cognitive limits can't keep up with the change of work environments. Mental workload has been an important factors in designing modem work environments such as human-computer interaction. Designing man-machine systems requires knowledge and evaluation of the human cognitive processes which control information flow workload. Futhermore, under an urgent situation, human operator may suffer the work stress, work error, and resultant deleterious work performance. To describe the work performance in the urgent work situations, with time stress and dynamic event occurence, a new concept of information density was introduced. For a series of experiments performed for this study, three independent variables(information amount system processing time, information density) were evaluated using such dependent variables as reaction time, number of error, and number of failure. The results of statistical anlysiss indicate that the amount of information effected on all of five dependent measure. Number of failure and number of secondary task score were effected by both amount of information and operational speed of system, but reaction time of secondary task were effected by both amount of information and information density.

• Journal of Educational Research in Mathematics
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• v.20 no.3
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• pp.413-444
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• 2010

The purpose of the present study is to develop an instrument of mathematical learning motivation and causal attribution for students and to analyze the results of the instrument. Based on the literature review, mathematical learning motivation is the cumulative effects of self-assessment and self-regulation in mathematical learning and achievement experience. Three factors of mathematical learning motivation is identified as self-regulatory efficacy, task difficulty and mathematical anxiety with 17 self-regulatory efficacy items, 9 task difficulty items and 9 mathematical anxiety items. Three factors of causal attribution for success is identified as ability/effort, luck, and other person with 6 ability/effort items, 4 luck items and 3 other person items. Also, four factors of causal attribution for failure is identified as ability, effort, luck, and other person with 3 ability items, 7 effort items, 3 luck items and 4 other person items. The instrument of mathematical learning motivation and causal attribution for success and failure was administered to 919 middle school students from eight different middle middle schools in Seoul, Gyeonggi-Do, Busan, jeolla-Do area. The correlation of three factors of mathematical learning motivation was calculated. As a result, a positive correlation between self-regulatory efficacy and task difficulty was appeared but mathematical anxiety has a negative correlation with self-regulatory efficacy and task difficulty. This study also examined the differences about mathematical learning motivation's sub-factors shown by three groups of mathematics achievement level. Students of higher achievement level showed that the degree of self-regulatory efficacy and task difficulty was higher than that of lower level group. Students of lowest achievement level showed significantly higher mathematical anxiety degree than that of middle and high group. Students that have higher degree of self-regulatory efficacy and task difficulty preference were attributed into ability/effort cause toward success of mathematics achievement. Also, Male students preferred more difficult task and higher degree of self-regulatory efficacy in mathematics learning than female students. On the contrary, Female students showed higher mathematical anxiety level than male students.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.1
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• pp.274-283
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• 2016

The study of maintenance planning is important in military weapon systems because it can improve their availability and reduce the operational and maintenance cost during the total life cycle. In maintenance planning, it is important to determine the preventive maintenance task and its optimal interval. This paper focuses on the hard time task, which is one of the preventive maintenance tasks. A hard time task removes an item or restorative action before some specified maximum age limit to prevent functional failure. The Monte-Carlo simulation model was proposed to help understand the cost effectiveness of a hard time task. In the simulation, various shape parameters of the Weibull distribution and cost ratio of corrective maintenance to preventive maintenance were assumed. Using a Monte-Carlo simulation, a quantified cost saving effect and optimal preventive maintenance interval were suggested.

• Journal of the Korean Society of Food Culture
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• v.29 no.4
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• pp.326-335
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• 2014

The purpose of this study was to investigate factors influencing sales of health functional foods by door-to-door saleswomen. A total of 450 women who worked as door-to-door salespersons in Seoul were enrolled. The survey questionnaire was composed of five parts as follows: general characteristics, factors related with door-to-door sales process, task education, competency required for door-to-door salespersons, and customer relationship beliefs. The survey was conducted in October 2011. Finally, data on 302 subjects were statistically analyzed using the SPSS 17.0 package program. Reason for sales of health functional foods (p<0.01), time required for sales promotion (p<0.001), difficulties during sales of health functional foods (p<0.05), satisfaction of task education (p<0.01), and failure of salesperson's memory as problems of task education (p<0.01) were significantly associated with sales of health functional foods. However, means of sales promotion, frequency and time of task education, and competency required for door-to-door salespersons were not significantly related with sales of health functional foods. Customer relationship beliefs did not show significant association with sales of health functional foods either. In conclusion, certain factors were associated with sales of health functional foods by door-to-door saleswomen. These results provide an understanding for sales of door-to-door health functional foods and provide basic information for preparation of task education for health functional food saleswomen and marketing.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.1
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• pp.35-57
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• 2021

Fog computing aims to provide the solution of bandwidth, network latency and energy consumption problems of cloud computing. Likewise, management of data generated by healthcare IoT devices is one of the significant applications of fog computing. Huge amount of data is being generated by healthcare IoT devices and such types of data is required to be managed efficiently, with low latency, without failure, and with minimum energy consumption and low cost. Failures of task or node can cause more latency, maximum energy consumption and high cost. Thus, a failure free, cost efficient, and energy aware management and scheduling scheme for data generated by healthcare IoT devices not only improves the performance of the system but also saves the precious lives of patients because of due to minimum latency and provision of fault tolerance. Therefore, to address all such challenges with regard to data management and fault tolerance, we have presented a Fault Tolerant Data management (FTDM) scheme for healthcare IoT in fog computing. In FTDM, the data generated by healthcare IoT devices is efficiently organized and managed through well-defined components and steps. A two way fault-tolerant mechanism i.e., task-based fault-tolerance and node-based fault-tolerance, is provided in FTDM through which failure of tasks and nodes are managed. The paper considers energy consumption, execution cost, network usage, latency, and execution time as performance evaluation parameters. The simulation results show significantly improvements which are performed using iFogSim. Further, the simulation results show that the proposed FTDM strategy reduces energy consumption 3.97%, execution cost 5.09%, network usage 25.88%, latency 44.15% and execution time 48.89% as compared with existing Greedy Knapsack Scheduling (GKS) strategy. Moreover, it is worthwhile to mention that sometimes the patients are required to be treated remotely due to non-availability of facilities or due to some infectious diseases such as COVID-19. Thus, in such circumstances, the proposed strategy is significantly efficient.

• Nuclear Engineering and Technology
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• v.49 no.2
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• pp.349-359
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• 2017

During the past 25 years, in the context of probabilistic safety assessment, efforts have been directed towards establishment of comprehensive pipe failure event databases as a foundation for exploratory research to better understand how to effectively organize a piping reliability analysis task. The focused pipe failure database development efforts have progressed well with the development of piping reliability analysis frameworks that utilize the full body of service experience data, fracture mechanics analysis insights, expert elicitation results that are rolled into an integrated and risk-informed approach to the estimation of piping reliability parameters with full recognition of the embedded uncertainties. The discussion in this paper builds on a major collection of operating experience data (more than 11,000 pipe failure records) and the associated lessons learned from data analysis and data applications spanning three decades. The piping reliability analysis lessons learned have been obtained from the derivation of pipe leak and rupture frequencies for corrosion resistant piping in a raw water environment, loss-of-coolant-accident frequencies given degradation mitigation, high-energy pipe break analysis, moderate-energy pipe break analysis, and numerous plant-specific applications of a statistical piping reliability model framework. Conclusions are presented regarding the feasibility of determining and incorporating aging effects into probabilistic safety assessment models.

• Journal of Distribution Science
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• v.18 no.8
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• pp.35-45
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• 2020

Purpose: Do close linkages among employees during service encounters always enhance customer satisfaction? Drawing on literature in social psychology, this research argues that under certain circumstances close linkages among employees undermine customer satisfaction. More specifically, this research explores a service failure context and shows that higher task interaction among employees during service encounters leads to higher perceived firm entitativity, resulting in an individual employee's service failure being detrimental to customer satisfaction with the firm. Data and research methodology: A series of experiments using scenarios across different service contexts was used in order to test hypotheses. Data was collected via Amazon Mechanical Turk and the models were tested using Hayes PROCESS. Results: The results show that interactions among employees during service result in 1) lower satisfaction with the firm and 2) lower revisit intentions in the future when there is a service failure by an individual employee. Following the main effects analysis, mediation analysis shows that the effect of employee interaction on customer satisfaction with the firm and revisit intention is mediated by perceived firm entitativity. Implications: By examining contexts where employee interaction may be detrimental to firms, this research provides novel insights on how to manage communications among service employees.