• Journal of Korean Society of Industrial and Systems Engineering
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• v.22 no.50
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• pp.23-32
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• 1999

Reliability and maintainability allocation in the analysis of the system's design, with the objective of planning and installing the individual components in such a way that the system performance is achieved. This paper has been made to solve an important task in reliability management of manufacturing systems within the general objective being to increase productivity while maintaining costs low. Thus, the purpose of this paper is to provide an analytical approach to determine an optimal reliability and maintainability allocation, trading off among system performance and parts investment costs. Two important considerations will be addressed in this regard : (ⅰ) determine the reliability and maintainability allocation of parts which maximizes a given production index, having fixed the total cost of investments ; and (ⅱ) determine the reliability and maintainability allocation which minimizes the total cost of investments, having fixed a minimum acceptable level of productivity. The procedure proposed in this paper is able to provide to managers and designers useful indications on the reliability and maintainability characteristics of parts in series -parallel systems. And this heuristic model is a decision support tool for contractors who are involved in large scale design projects such as ship and aircraft design. Numerical examples prove that an approximate expression of the average throughput rate is sufficiently accurate to be used in a numerical optimization method.

• IEMEK Journal of Embedded Systems and Applications
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• v.15 no.4
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• pp.197-204
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• 2020

The ImageNet dataset is a large scale dataset and contains various natural scene images. In this paper, we propose a convolutional neural network (CNN)-based weighted ensemble technique for the ImageNet classification task. First, in order to fuse several models, our technique uses weights for each model, unlike the existing average-based ensemble technique. Then we propose an algorithm that automatically finds the coefficients used in later ensemble process. Our algorithm sequentially selects the model with the best performance of the validation set, and then obtains a weight that improves performance when combined with existing selected models. We applied the proposed algorithm to a total of 13 heterogeneous models, and as a result, 5 models were selected. These selected models were combined with weights, and we achieved 3.297% Top-5 error rate on the ImageNet test dataset.

• Industrial Engineering and Management Systems
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• v.11 no.4
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• pp.397-405
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• 2012

This research proposes a framework of buffer management for multi-project systems in the critical chain project management (CCPM) method, expressed in the form of max-plus linear (MPL) representation. Since time buffers are inserted in the projects for absorbing uncertainties in task durations and protecting the completion times, the proposed method provides a procedure for frequently surveying the rates of consumed buffers and the rate of elapsed times. Their relation expresses the performance of the projects which is plotted on a chart through the completed processes. The chart presents the current performance of the projects and their interaction, which alerts managers to make necessary decisions at the right time for managing each project and the entire multi-project system. The proposed framework can analyze the complex system readily, and it enables managers to make an effective decision on scheduling. The effectiveness of the framework is demonstrated through a numerical example.

• Journal of Biomedical Engineering Research
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• v.27 no.5
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• pp.237-244
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• 2006

This study proposes an approach to the performance improvement of EMG(Electromyogram) pattern recognition. MFCC(Mel-Frequency Cepstral Coefficients)'s approach is molded after the characteristics of the human hearing organ. While it supplies the most typical feature in frequency domain, it should be reorganized to detect the features in EMG signal. And the dynamic aspects of EMG are important for a task, such as a continuous prosthetic control or various time length EMG signal recognition, which have not been successfully mastered by the most approaches. Thus, this paper proposes reorganized MFCC and HMM-GMM, which is adaptable for the dynamic features of the signal. Moreover, it requires an analysis on the most suitable system setting fur EMG pattern recognition. To meet the requirement, this study balanced the recognition-rate against the error-rates produced by the various settings when loaming based on the EMG data for each motion.

• Industrial Engineering and Management Systems
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• v.4 no.1
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• pp.36-46
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• 2005

In traditional production lines, such as assembly lines, each worker is usually assigned to a fixed task, which is beneficial since it reduces the amount of training needed for workers to master their assigned tasks. However, when workers complete their tasks at different speeds, the slowest worker will determine the overall pace of the production line and limit production. To avoid this problem, the self-balancing production line was introduced. In this type of production line, each worker works dynamically, thus they can maintain balanced production. Previous research analyzing the performance of these lines has ignored the walk-back time associated with dynamic workers. U-shaped production lines have also been analyzed and policies for such lines have been proposed. However, the walk-back time cannot be ignored in practice, and research taking this factor into account is needed to enable balanced production and thus the maximum production rate. In this paper, we propose production policies for a production line with the walk-back time taken into account, and define and analyze the conditions for self-balancing. Furthermore, we have compared the performance of such a line with that of other production lines under the same conditions, and the results show the superiority of this line in certain cases.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.6
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• pp.1011-1016
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• 2020

Rapid change in network topology in high-speed VANET(: Vehicular Ad Hoc Network) is an important task for routing protocol design. Selecting the next hop relay node that affects the performance of the routing protocol is a difficult process. The disadvantages of AODV(: Ad Hoc On-Demand Distance Vector) related to VANET are end-to-end delay and packet loss. This paper proposes the AAODV (Advanced AODV) technique to reduce the number of RREQ (: Route Request) and RREP (: Route Reply) messages by modifying the AODV routing protocol and adding direction parameters and 2-step filtering. It can be seen that the proposed AAODV reduces packet loss and minimizes the effect of direction parameters, thereby increasing packet delivery rate and reducing end-to-end delay.

• Journal of Venture Innovation
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• v.5 no.1
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• pp.75-90
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• 2022

Start-up is a very important task for the development of the country as well as individuals for entrepreneurs with novel ideas, experiences, and know-how. Most of the new start-ups often have no start-up experience, and the government and universities operate start-up incubator centers so that start-up companies can grow and develop. The goal is to improve the success rate of technology-based start-ups. It supports various needs of start-up companies and supports start-up companies to succeed by enabling them to maximize their potential. The expected effect of the start-up incubator center can be said to be a contribution to the development of the national economy through the revitalization of start-ups. This study aims to consider ways to achieve performance through the efficient operation of domestic start-up incubator centers.

• Journal of Information Technology Applications and Management
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• v.30 no.3
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• pp.1-13
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• 2023

Demand forecasting is a crucial task for an online retail where has to manage daily fresh foods effectively. Failing in forecasting results loss of profitability because of incompetent inventory management. This study investigated the optimal performance of different forecasting models for a very short shelf-life product. Demand data of 13 perishable items with aging of 210 days were used for analysis. Our comparison results of four methods: Trivial Identity, Seasonal Naïve, Feed-Forward and Autoregressive Recurrent Neural Networks (DeepAR) reveals that DeepAR outperforms with the lowest MAPE. This study also suggests the managerial implications by employing coefficient of variation (CV) as demand variation indicators. Three classes: Low, Medium and High variation are introduced for classify 13 products into groups. Our analysis found that DeepAR is suitable for medium and high variations, while the low group can use any methods. With this approach, the case can gain benefit of better fill-rate performance.

• Journal of the Korean Dietetic Association
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• v.1 no.1
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• pp.66-78
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• 1995

The purposes of this study were to a) analyze the dietitian's job as a foodservice manager in employee foodservice, b) examine the performance and importance levels of management activities, c) determine factors affecting performance and importance levels of management activities. A job analysis questionnaires were developed and mailed to 65 dietitians who were members of The Korean Dietetic Association Practice Group, members with management responsibilities in employee foodservices. Completed questionnaires were received from 32 dietitians for a response rate of 49%. The questionnaire contained two parts with a total of 99 statements. Statistical data analysis was completed using the SAS programs for descriptive analysis, Wilcoxon signed ranks test, Wilcoxon rank sum test, and pearson correlation. The results of this study can be summarized as follows. 1. The average score of performance and importance levels on management activities were 3.11, 3.99 respectively. And they were significantly different(p<0.001). 2. The performance level was significantly correlated to working hours per week(r= .6598, p<.01), number of meals(r=.3934, p<.05) and foodcost(r=.5208, p<.05). 3. The importance level on management activities was significantly correlated to working hours per week(r=.6214, p<.05), number of meals(r= .4161, p<.05) and foodcost (r =.6920, p<.01).

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.11
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• pp.5497-5507
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• 2013

The purpose of this study was to investigate the effects of dark side personality traits on self-other rating agreement in leader effectiveness. Data were collected from 80 team leaders and their peers in college. Peers who conducted a team project were asked to assess performance of their team leaders on leader effectiveness, task performance, and contextual performance. The leaders were also asked to self-rate their performance on the same measures. Results indicated that there was disagreement of perceptions about personality traits between leader's self-ratings and the rating of others. First, leaders considered their own Bold, Diligent behaviors as positive influence on their leadership-related criteria, whereas peers of these leaders provided negative ratings. Also, leaders viewed Leisurely and Cautious characteristics as unrelated or negative to performance, whereas peers perceiveed these personality traits as positive to performance. Suggestions for future research were provided based on the findings.