• The Transactions of the Korean Institute of Power Electronics
• /
• v.24 no.4
• /
• pp.273-278
• /
• 2019

This study proposes a method for improving the overmodulation performance of a three-phase inverter to obtain an enhanced output torque for the AC motors. In the inverter-fed AC motor drives, the output torque of the motor can be enhanced by utilizing the overmodulation region as well as the linear modulation regions of the inverter. The overmodulation method is used for this overmodulation operation of the inverter. However, the voltage gain, the ratio of the output voltage of the inverter to the reference voltage achieved by the conventional overmodulation methods becomes nonlinearly smaller than unity. Therefore, the effect of improving the output torque of the AC motors is insignificant even when the overmodulation region is utilized. In this study, we propose a method that improves the overmodulation performance of the inverter by compensating the limited amount of the reference voltage in the overmodulation operation to enhance the output torque of the AC motors. The effectiveness of the proposed method is verified through the simulations and experiments with an 800 W permanent magnet synchronous motor.

• Journal of the Korean housing association
• /
• v.24 no.6
• /
• pp.103-110
• /
• 2013

The purpose of this study is to estimate the perception of elderly residents on the residential environment improving projects and suggest the political implications. The survey include questionnaires about the importance and the satisfaction level on the project maintenance factors. The results were statistically analyzed by Importance-Performance Analysis (IPA). As the result of the study, firstly, it shows that 'the possible overkill area' on the IPA action grid includes none of factors except 'landscape' which is very similar to mean of performance score. the result of analysis means that the project is very efficient. Secondly, the policy is necessary to improve 'pedestrian passage', 'public open space' and 'transportation environment'. Considering elderly residents especially 'pedestrian passage' and 'public open space' are in need of improvement immediately. In detail 'traffic facility', building 'urban park' and 'pedestrian passage', 'paving of pedestrian passage', 'children's playground' are in need of improvement as well. The results of analysis on elderly and non-elderly residents of Yonnam project may be important foundation for future strategies for improvement.

• The KSFM Journal of Fluid Machinery
• /
• v.9 no.3 s.36
• /
• pp.29-35
• /
• 2006

There are high expectations of improving the performance of a centrifugal pump in the range of very low specific speed which has been developed recently for the use instead of a conventional positive displacement pump. However, even though elaborated studies has been done for the pump intensively, the pump performance has not increased so much. Also, it is difficult to find detailed information from published literatures for suction performance of the very low specific speed centrifugal pump. Therefore, this study is aimed to improve the pump performance more and to make clear suction performance of the very low specific speed centrifugal pump. Recircular flow stopper is installed on the pump casing wall at the region of impeller outlet to improve the pump performance and J-Groove is also installed at the inlet of the pump casing for the purpose of suppressing occurrence of cavitation as well as improving pump performance. The result suggests that the simultaneous improvement of pump performance and suction performance of the very low specific speed centrifugal pump is possible by adopting optimum configuration of the recirculation flow stopper and J-Groove.

• Proceedings of the KIPE Conference
• /
• 2000.07a
• /
• pp.641-644
• /
• 2000

Recently As the performance of the personal computer has been improving rapidly lots of research for the pc-based numerical computer actively progress in an easy repair maintenance and improving the performance with less cost. This paper presents the design using complex programmable logic device(CPLD). The CPU of Motion Controller that function as the real time control of the independent multi-axis motion the error-detect module and external I/O control made use of 80C196KC, In this paper The PC-NC effectively distributed to the load of NCK(numerical computer kernel) and have the advantage of high speed and precision.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.8 no.2
• /
• pp.280-285
• /
• 2007

This paper proposes a technique improving performance using word senses and user feedback in web information retrieval, compared with the retrieval based on ambiguous user query and index. Disambiguation using word senses is very important processing for improving performance by eliminating the irrelevant pages from the result. According to semantic categories of nouns which are used as index for retrieval, we build the word sense knowledge-base and categorize the web pages. It can improve the performance of retrieval system with user feedback deciding the query sense and information seeking behavior to web pages.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.41 no.1
• /
• pp.64-69
• /
• 2005

In spite of many efforts, in the design of high speed fishing vessel the sea-keeping performance improvement without neglection of resistance-propulsion performance by hull form itself has its limitations. In this paper, the development of sea-keeping improving appendage pitching and trim improver for high speed planing hull on behalf of the hull form of fishing vessel has been introduced. The developed appendage verified its effectiveness in the full scale test and also has been proved the better resistance performance in the model test and full scale test.

• International Journal of Advanced Culture Technology
• /
• v.7 no.4
• /
• pp.56-62
• /
• 2019

Recently, research using artificial neural networks has further expanded the field of neural network optimization and automatic structuring from improving inference accuracy. The performance of the machine learning algorithm depends on how the hyperparameters are configured. Open-source hyperparameter optimization software can be an important step forward in improving the performance of machine learning algorithms. In this paper, we review open-source hyperparameter optimization softwares.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2009.05a
• /
• pp.872-875
• /
• 2009

In a bankruptcy prediction model, the accuracy is one of crucial performance measures due to its significant economic impacts. Ensemble is one of widely used methods for improving the performance of classification and prediction models. Two popular ensemble methods, Bagging and Boosting, have been applied with great success to various machine learning problems using mostly decision trees as base classifiers. In this paper, we analyze the performance of boosted neural networks for improving the performance of traditional neural networks on bankruptcy prediction tasks. Experimental results on Korean firms indicated that the boosted neural networks showed the improved performance over traditional neural networks.

• Proceedings of the KIPE Conference
• /
• 2018.07a
• /
• pp.308-309
• /
• 2018

This paper proposes new D/A(Digital to Analog) Design method for improving accuracy in high-performance test equipment. The proposed new D/A design can improve accuracy of the equipment even with low-resolution D/A converters. The validity of proposed D/A design is verified by analysis and experiment.

• Journal of Construction Engineering and Project Management
• /
• v.5 no.1
• /
• pp.1-10
• /
• 2015

In construction, stakeholders of extended project team play a key role in the overall project performance. Successful integration of stakeholders demands for good management practices at strategic, operational and project levels. Targets and measures to improve the stakeholder performance encourage the creativity and willingness of stakeholders of extended project team to develop the better ways to achieve the project objectives. This paper presents a generic descriptive method, showing how stakeholder's ability and influence impacts on project performance in the construction sector. The findings of a series of interviews with key informants are presented and the following main conclusion is drawn: improving project performance through stakeholder's contribution and measuring their performance can strengthen the project performance. This innovative approach which redefines the process of improving the project performance in construction projects will be of interest to those who intend to manage the projects in practice as well as to those who interested in advancing theory.