• Advances in aircraft and spacecraft science
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• v.6 no.6
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• pp.529-550
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• 2019

The effect of multiple process parameters on a set of continuous response variables is, especially in experimental designs, difficult and intricate to determine. Due to the complexity in aeroacoustic and vibroacoustic studies, the often-performed simple one-factor-at-a-time method turns out to be the least effective approach. In contrast, the statistical Design of Experiments is a technique used with the objective to maximize the obtained information while keeping the experimental effort at a minimum. The presented work aims at giving insights on Design of Experiments applied to aeroacoustic and vibroacoustic problems while comparing different experimental designs and approximation models. For this purpose, an experimental rig of a ducted low-pressure fan is developed that allows gathering data of both, aerodynamic and aeroacoustic nature while analysing three independent process parameters. The experimental designs used to sample the design space are a Central Composite design and a Box-Behnken design, both used to model a response surface regression, and Latin Hypercube sampling to model an Artificial Neural network. The results indicate that Latin Hypercube sampling extracts information that is more diverse and, in combination with an Artificial Neural network, outperforms the quadratic response surface regressions. It is shown that the Latin Hypercube sampling, initially developed for computer-aided experiments, can also be used as an experimental design. To further increase the benefit of the presented approach, spectral information of every experimental test point is extracted and Artificial Neural networks are chosen for modelling the spectral information since they show to be the most universal approximators.

• Ocean and Polar Research
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• v.38 no.4
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• pp.339-345
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• 2016

Stable water vapor isotopes have been utilized as a tracer for studying atmospheric global circulations, climate change and paleoclimate with ice cores. Recently, since laser spectroscopy has been available, water vapor isotopes can be measured more precisely and continuously. Studies of water vapor isotopes have been conducted over the world, but it is the early stage in south Korea. For vapor isotopes study, a cryogenic sampling device for water vapor isotopes has been developed. The cryogenic sampling device consists of the dewar bottle, filled with extremely low temperature material and impinger connected with a vacuum pump. Impinger stays put in the dewar bottle to change the water vapor which passes through the inside of impinger into the solid phase as ice. The fact that water vapor has not sampled completely leads to isotopic fractionation in the impinger. To minimize the isotopic fractionation during sampling water vapor, we have tested the method using a serial connection with two sets of impinger device in the laboratory. We trapped 98.02% of water vapor in the first trap and the isotopic difference of the trapped water vapor between two impinger were about 20‰ and 6‰ for hydrogen and oxygen, respectively. Considering the amount of water vapor trapped in each impinger, the isotopic differences for hydrogen and oxygen were 0.33‰ and 0.06‰, respectively, which is significantly smaller than the precision of isotopic measurements. This work can conclude that there is no significant fractionation during water vapor trapping.

• Analytical Science and Technology
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• v.18 no.4
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• pp.338-343
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• 2005

In this work, sample loss of reduced sulfur compounds (RSC) was investigated with respect to bag sampling techniques. For comparison purpose, calibration slopes were obtained by analyzing standards prepared by 'within syringe dilution' (WSD) method against those made either by 'Tedlar bag dilution' (TBD) or by 'polyester aluminum bag dilution' (PBD) method. The results indicated that the recovery rate of TBD showed the mean values of about 87%, while those of PBD about 77%. Despite the fact that sample loss is inevitable, precise sampling of reduced sulfur compounds may still be possible, if one acknowledges and be prepared for such loss rates of bag sampling methods.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.7
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• pp.545-551
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• 2013

Timing recovery loop composed of the Timing Error Detector(TED), loop filter and resampler is widely used for the timing synchronization in MQASK receivers. Since TED is sensitive to the delay between the symbol period of the signal and sampling period, the output is averaged out when the symbol rate and sampling rate are quite different the recovery loop cannot work at all. This paper presents a sampling frequency discriminator (SRD), which detects the frequency offset of the sampling clock to the symbol clock of the MQASK data transmitted. Employing the SRD, the closed loop timing recovery scheme performs the frequency-aided timing acquisition and achieve the synchronization at extremely high sampling frequency offset, which can be used in variable symbol rate MQASK receivers.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.782-787
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• 2004

In the conventional sliding mode control technique, a priori knowledge of the bound of external disturbances or/and parameter uncertainties is required to assure control robustness. This, however, may not be easy to obtain in practical situation. This work presents a novel methodology, a sliding mode controller with perturbation estimator, which offers a robust control performance without a priori knowledge about the perturbations (disturbances and parameter uncertainties). The proposed technique is featured by an integrated average value of the imposed perturbation over a certain sampling period. This work also proposes two effective actuating methods of the perturbation estimator: on-off condition and filtering condition. In order to demonstrate the effectiveness of the proposed methodology, a two-link robotic system is adopted and its position control performance is evaluated. In addition, a comparative work between the conventional technique and the proposed one is undertaken.

• International Journal of Knowledge Content Development & Technology
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• v.4 no.2
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• pp.25-47
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• 2014

The goal of the present study is to explore IM interruption by relating it to media choices and purposes of IM use in the workplace. Two major media choice concepts were: media richness and social influence; while four purposes of IM use were: organization work, knowledge work, socializing, and boundary spanning activities. Data (N = 283) were collected via a combination of convenience and snowball sampling of "computer-using workers" in Taiwan, based on the Standard Occupational Classification system published by the Taiwan government. Results indicated that media choice works better than purpose of IM use to explain IM interruption. Among them, social influence was the best predictor to IM interruption in the workplace. In addition, instant feedback and personalization provided by IM, and IM usage for the purposes of knowledge work and socializing, also relate to IM interruption in the workplace.

• Fibers and Polymers
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• v.6 no.4
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• pp.339-342
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• 2005

In this paper, a hand-operating method (tiled test method) of the wool-blending sample is made out, and make use of the method, the test of wool-blending bundle in different blending ratio is accomplished. According to the test data, the synthesis method of the stretch curve is worked out and the synthesis software for the typical stretch curve of wool-blending bundle is designed. Through laboratory hand-operating method, the blending fasciculus applying to fiber bundle test can be obtained in a short time. Calculation for sampling is accomplished in the article. We bring up 9 new signs to describe the characteristics of the curve behind peak for the first time: elongation behind peak (HE), elongation percentage behind peak (HEP), relative elongation rate behind peak (RHE), total break work $(W_a)$, break work behind peak (HW), break work coefficient behind peak (HWC), elongation percentage of half-load behind peak (HEL), load percentage of half-elongation behind peak (HLE), break efficiency behind peak (HEC).

• Safety and Health at Work
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• v.8 no.1
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• pp.72-76
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• 2017

Background: Workplace victimization is considered a major social stressor with significant implications for the wellbeing of employees and organizations. The aim of this study was to examine the influences of employees' personality traits and organizational politics on workplace victimization among Ghanaian employees. Methods: Using a cross-sectional design, data were collected from 631 employees selected from diverse occupations through convenience sampling. Data collection tools were standardized questionnaires that measured experiences of negative acts at work (victimization), the Big Five personality traits, and organizational politics. Results: The results from hierarchical multiple regression analysis showed that among the personality traits neuroticism and conscientiousness had significant, albeit weak relationships with victimization. Organizational politics had a significant positive relationship with workplace victimization beyond employees' personality. Conclusion: The study demonstrates that compared with personal characteristics such as personality traits, work environment factors such as organizational politics have a stronger influence on the occurrence of workplace victimization.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.11 no.18
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• pp.41-57
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• 1988

This study was carried out to furnish information for the appropriate standard work time measure and applicate system development that help for korean manufacturers. As a research methodology of the study, the questionnaire survey by sampling nine hundreds registerd corporation, was conducted to find the scientific management technique level (for especially standard work time). By crossectionally analyzing the survey results, placed primary emphasis on the study to comparison with employee scale and types of industry classify. The contents of subjective study art as follows; (1) Establish state of standard time(S. T) (2) Mainly technique for establish S. T (3) Institute level and correctness of S. T (4) Practical use of S. T (5) Performance rating and Allowance rate (6) Advantage and disadvantage to application results.

• Asia pacific journal of information systems
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• v.28 no.3
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• pp.167-182
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• 2018

The purpose of this study is to investigate the relationship between knowledge sharing and academic performance in the context of quality-assurance related work. It furthermore aims to explore the role of information technology in mediating this relationship. Quantitative method was applied to collect data from the participants using an online-based questionnaire. Convenience sampling technique was used. The responses were collected from 140 participants in a university from Saudi Arabia. The study found a strong positive relationship between knowledge sharing and individual performance. It was also found out that information technology partially mediates the relationship between knowledge sharing and individual performance. The research unearths the significant contribution made by information technology in mediating the relationship between individual-level knowledge sharing and the individual performance. This helps to understand the positive impacts on individual work performance in institutions of higher education that would be derived if individuals use various forms of IT to share knowledge. The focus of the research is the individual performance as the pertinent contribution towards positive outcomes in institutional performance.