• Industrial Engineering and Management Systems
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• v.2 no.1
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• pp.1-8
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• 2003

Among many dimensional or dimensionless amplitude parameters, kurtosis and ID Factor are said to be sensitive good parameters for machine diagnosis. In this paper, a simplified calculation method for both parameters is introduced when impact vibration arise in the observed data. Compared with the past papers' results, this new method shows a good result which fit well. This calculation method is simple enough to be executed even on a pocketsize calculator and is very practical at the factory of maintenance field. This can be installed in microcomputer chips and utilized as a tool for early stage detection of the failure.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.4
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• pp.601-611
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• 2010

Currently, a life cycle cost estimates(LCCE) is the most important factor in weapon system acquisition process. However, operation and maintenance(O&M) cost related studies are insufficient from the previous literature survey. O&M cost consists of various cost factors such a man power, maintenance and direct & indirect support costs. We have known that spare-parts cost is a key factor in the O&M cost. In this paper, we developed the spare-parts cost estimating relationships(CERs) of fixed-wing aircraft and armored vehicle weapon systems which include 4 historical cost drivers ; system acquisition cost, deterioration rate, localization rate, mission characteristic. Furthermore, we proposed the application methodologies that O&M cost estimating, total life cycle cost estimating and determination of the economic life using the spare-parts CERs.

• Proceedings of the KIEE Conference
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• 2006.07e
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• pp.51-52
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• 2006

Our company(KOWACO) has periodically performed off-line diagnostic test for 14 hydro generators (rated 11 kV over) for 15 years. In this paper, we summarized results of dissipation factor tip-up test and partial discharge test about these generators. Among these, we chose two generators and performed insulation reinforcement (cleaning and varnish painting). We compared change of insulation condition for the stator winding based upon off-line diagnostic test result before and after repair. Test result shows that insulation condition was improved after insulation reinforcement. This insulation reinforcement has a function to reduce cause of deterioration, so we can know that it extends lifetime of generator and it is a very important factor for stable operation of facilities.

• Journal of information and communication convergence engineering
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• v.21 no.3
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• pp.198-207
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• 2023

Responding to changes in artificial intelligence models and the data environment is crucial for increasing data-learning accuracy and inference stability of industrial applications. A learning model that is overfitted to specific training data leads to poor learning performance and a deterioration in flexibility. Therefore, an early stopping technique is used to stop learning at an appropriate time. However, this technique does not consider the homogeneity and independence of the data collected by heterogeneous nodes in a differential network environment, thus resulting in low learning accuracy and degradation of system performance. In this study, the generalization performance of neural networks is maximized, whereas the effect of the homogeneity of datasets is minimized by achieving an accuracy of 99.7%. This corresponds to a decrease in delay time by a factor of 2.33 and improvement in performance by a factor of 2.5 compared with the conventional method.

• Journal of Drive and Control
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• v.19 no.4
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• pp.54-61
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• 2022

This is a basic study analyzing emissions of an agricultural tractor during tillage operations. In this study, CO, THC, NOx, and PM considered as emission factor were analyzed during plow and rotary tillage operation by the tractor. Engine torque and rotational speed were measured through ECU. Engine power was calculated using engine torque and rotational speed. The emissions was calculated based on the number of units, rated power, load factor, and operating time. Results showed that the load factor was calculated almost twice, which was higher than 0.48. It was also observed that the emission of the tractor was variable for different agricultural operations because tractor loads were different based on operations. There was a difference in emissions due to differences in plow and rotary working hours. To estimate the emission of agricultural tractor based field operations in detail, it is necessary to consider TAF (Transient Adjustment Factor) and DFA (Deterioration factor). In the future, TAF and DFA will be considered to estimate emissions of the agricultural tractor. Finally, results of this study can contribute to the literature to estimate tractor emissions accurately.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.1
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• pp.35-43
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• 2012

In general, load carrying capacity, one of the load & resistance capacities in bridges, has more margins than the load carrying capacity evaluated with theoretical methods, unless there are severe damages, defects or material deterioration phenomena that can have a great impact on the behavior of bridges. However, errors have been already included in the current processes of loading tests and structural analysis for measuring load carrying capacity, thus devaluing the reliability of response adjustment factor. Therefore, this study found out the problems of existing electric resistance strain and displacement sensors in sensor suite to solve the problems with sensors and the errors in the appropriateness of structural analysis model, thereby leading to the changes into an optical fiber smart sensor with excellent performance. Besides, the study attempted to ensure the accuracy of response adjustment factor by selecting the optimal models through the interpretation of various structural analysis models.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.4
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• pp.788-794
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• 2009

To assess the condition of stator insulation, nondestructive tests were performed on twenty five coil groups and twenty six motors. The stator windings has nominal ratings of 6.6kV and are classified into five coil groups ;one group with healthy insulation and four groups with four different types of artificial defects. After completing nondestructive tests, the AC voltage applied to the stator windings was gradually increasing until insulation failure in order to obtain the breakdown voltage. No.1, No.2 and No.6 of 6.6kV motors failed near rated voltage of 14kV, 8.7kV and 14kV, respectively. The breakdown voltage of three motors was lower that expected for good quality coils(14.2kV) in 6.6kV motors. No.3 and No.6 of 4.16kV motors failed near rated voltage of 5.6kV and 4.2kV, respectively. Almost all of failures were located in a line-end coil at the exit from the core slot. The breakdown voltages and the types of defects showed strong relation to the stator insulation tests such as in the case of AC current, dissipation factor(tan${\delta}$) and partial discharge magnitude.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.4
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• pp.85-92
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• 2002

To investigate the safety of the in-use vehicles emission against the tail-pipe emission regulation, in-use vehicles emission trend according to vehicle mileage should be known. But it is impossible to collect all vehicles emission data In order to know that. Therefore, it is necessary to establish a statistically meaningful inference method that can be used generally to estimate in-use vehicles emissions distribution according to the vehicle mileage with relatively less in-use vehicles emission data. To do this, a linear regression model that solved the problems of data normality and common variance of error was studied. As a way that can secure the data normality, In(emission) instead of emission itself was used as a sampled data. And a reciprocal of mileage was suggested as a factor to secure common variance of error. As an example, 36 data of FTP-75 test were handled in this study. As a result, using average value and standard deviation at each mileage which were inferred from a linear regression model, probability density distribution and cumulative distribution of emissions according to the vehicle mileage were obtained and it was possible to predict the deterioration factor through full useful life mileage and also possible to decide whether those in-use vehicles will meet the tail-pipe emission regulations or not.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.12
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• pp.82-90
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• 2019

This analysis demonstrates the effective removal of heat generated from a solar panel's output degradation factor solar cells (the solar panel's output deterioration factor), and solves the problems of oxidation and corrosion in existing metal heat sinks. The heat-dissipating test specimen was prepared using carbon materials; then, its thermal conductivity and its effectiveness in reducing temperatures were studied using heat transfer numerical analysis. As a result, the test specimen of the 30g/㎡ basis weight containing 80% of carbon fiber impregnated with carbon ink showed the highest thermal conductivity 6.96 W/(m K). This is because the surface that directly contacted the solar panel had almost no pores, and the conduction of heat to the panels appeared to be active. In addition, a large surface area was exposed to the atmosphere, which is considered advantageous in heat dissipation. Finally, numerical analysis confirmed the temperature reduction effectiveness of 2.18℃ in a solar panel and 1.08℃ in a solar cell, depending on the application of heat dissipating materials.

• Culinary science and hospitality research
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• v.7 no.2
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• pp.195-215
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• 2001

This study is of an analysis of the kinds of influences on the subordinate variables through the adjusting variables by the independent variables which serve as the perception factor of job stress. also This study, with taking the workers for the hotel employees who are in the room, food & beverage and cook, was carried out so as to analyze deeply and throughly the stress of work they experience in doing their job and the tension incited from this stress and the strategy used for meeting this stress to grope for raising plan for the degree of satisfaction with their job of the workers for the hotel. In order for, this study ran paralled with literature study and research study, taking 615 workers who are now working in hotel. Job stress is easily negligible in hotel business not only because it is hard to identify and measure its concrete entity on account of its intangible characteristic but also because it is impossible to check physically the relationship with each direct behavior. If job stress continue, however, it can cause neglect of duty, change of occupation, deterioration of service quality and eventually aggravate the cost of a hotel business and decrease the hotel sales. Consequently, it is highly necessary to increase job satisfaction by identifying systematically and eliminating the stress factor of hotel employees in order to accomplish particularly experience unique job stress in the course of contact since they should provide the customer with their services.