• Journal of Power Electronics
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• v.18 no.1
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• pp.70-80
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• 2018

A novel strategy based on a zero common mode voltage pulse-width modulation (ZCMV-PWM) technique and zero-sequence circulating current (ZSCC) feedback control is proposed in this study to eliminate ZSCCs between three-level neutral point clamped (NPC) voltage source inverters, with common AC and DC buses, that are operating in parallel. First, an equivalent model of ZSCC in a three-phase three-level NPC inverter paralleled system is developed. Second, on the basis of the analysis of the excitation source of ZSCCs, i.e., the difference in common mode voltages (CMVs) between paralleled inverters, the ZCMV-PWM method is presented to reduce CMVs, and a simple electric circuit is adopted to control ZSCCs and neutral point potential. Finally, simulation and experiment are conducted to illustrate effectiveness of the proposed strategy. Results show that ZSCCs between paralleled inverters can be eliminated effectively under steady and dynamic states. Moreover, the proposed strategy exhibits the advantage of not requiring carrier synchronization. It can be utilized in inverters with different types of filter.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.4
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• pp.467-473
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• 2013

The addition of disconnect switches to a distribution feeder or the replacement of the manual switches with the automatic switches do, in general, increase reliability by decreasing the duration of the outage of many to the customers on the feeder and reducing the outage section. However, the improvement of reliability in power distribution system causes an increase of the investment cost, for example, replacement costs, labor costs, and so on. For this reason - the balance between investment and reliability improvement - many studies about the appropriate level of investment have been conducted. In this paper, we suggest the algorithm for determining the reasonable switch automation rate in the power distribution system. We evaluate the customer interruption cost and reliability for several cases - these cases relate with the switch automation rate - in the domestic metropolitan power distribution system, estimate the effectiveness of changing the manual switch to automatic switch quantitatively. These results can help the determining on the disconnect switch's automation rate.

• Journal of Power Electronics
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• v.17 no.2
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• pp.453-463
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• 2017

This paper discusses the measurement of frequency response functions for various dc-dc converters. The frequency domain identification procedure is applied to the measured frequency responses. The identified transfer functions are primarily used in developing behavioral models for dc-dc converters. Distributed power systems are based upon such converters in cascade, parallel and several other configurations. The system level analysis of a complete system becomes complex when the identified transfer functions are of high order. Therefore, a certain technique needs to be applied for order reduction of the identified transfer functions. During the process of order reduction, it has to be ensured that the system retains the dynamics of the full order system. The technique used here is based on the Hankel singular values of a system. A systematic procedure is given to retain the maximum energy states for the reduced order model. A dynamic analysis is performed for behavioral models based on full and reduced order frequency responses. The close agreement of results validates the effectiveness of the model order reduction. Stability is the key design objective for any system designer. Therefore, the measured frequency responses at the interface of the source and load are also used to predict stability of the system.

• Journal of the Korean housing association
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• v.19 no.1
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• pp.17-27
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• 2008

Recently, newly built apartments in Korea are provided various home automation (HA) systems based on information technology(IT) for residents' safer, healthier and more convenient living. However, the residents in these digital apartments are often not able to use the home automation systems effectively because of lack of their IT knowledge, attitude, or education. However, there are few researches have been done to find out the HA systems' real problems with regard to residents' aspects who use those systems everyday. The purpose of this study was to find out residents' current uses, satisfaction level and existing problems of HA systems by residents' POE. The findings of this study will give useful information to digital home construction companies to provide user-friendly digital home services for increasing users' satisfaction. One distinctive apartment equipped with home automation systems located in Seoul was selected for in-depth personal interview. The researcher developed a survey instrument and collected the data from 58 residents in January, 2007 who had been living there for more than a year. The results of the study found that critical problems were existed in several systems and they caused a lot of dissatisfaction from the residents. Also, some residents do not use several systems although they need to use them due to the burden of maintenance fee. Further detail findings and suggestions of this study were discussed.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.11a
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• pp.15-18
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• 2009

Due to its high dependency of manpower, construction work has several difficulties in terms of quality control, imbalance of supply and demand of qualified manpower, safety management for them and improvement of production. Such problems related to the management can be at some degree solved by introducing an automation facility. Since the unique environment of a construction site in the past was not structured, it is very hard to introduce a facility to automate construction work from operation of the equipment to assignment of where to work. This is a preliminary research for automation of construction work. In this study, the trend of development of a cutting-edge technology, RTLS, was researched and analyzed in order to review the possibility of utilizing RTLS in construction work and present a control mechanism for construction equipment. Although the presented mechanism is at the concept stage, which still has lots of restrictions to be solved, the application of the RTLS will be very much feasible. That is, if linkage of the study between the RTLS and the automation of construction is built, it will be expected to contribute to many fields such as cost reduction through efficient and systemic management, the reduction of construction period and precise construction as well as raising the level of the automation of domestic construction work.

• The Korean Journal of Community Living Science
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• v.18 no.2
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• pp.247-263
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• 2007

This study was complied to analyze the professional agricultural techniques level and to suggest a desirable direction for the professional education system for women farmer. The research was conducted by using in-field surveys and interviews. Data was gathered by questionnaire from 147 women farmer in five specialized crop regions: strawberry, cucumber, rose, apple, and oyster mushroom. The results obtained are as follows. First, the technique levels in computer usage and electronic commerce, machinery usage, pesticide and fertilizer utilization, facility automation, and eco-agricultural cultivation were low. Second, the demand for professional education, evaluated through technique level by standard management diagnosis, was recognized. Areas of concern included: cucumber (temperature control, carbonic acid gas control, grading, funds management), strawberry (light control, soil temperature control, irrigation watering, shipping), rose (temperature control, light control, funds management, cooperated management), oyster mushroom (growth cabinet sterilizer), and apple (flower bud pinching, defloration, fruit thinning, funds management). Based on the results of this study, the following are suggestions for the planning of a professional education system for women farmer. First, it needs to address formal education in marketing, machinery usage, facilities automation, and techniques in pesticide and fertilizer utilization. Second, it needs to be a multi- level program with appropriate terminology at every level which is suitable to each age and ability of women farmer. Third, it needs a more comprehensive manual developed by need analysis of women farmer and a larger lecturer pool for professional education.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1355-1360
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• 2005

In this paper, we approach the problem of image filter design automation using a kind of intrinsic evolvable hardware architecture. For the purpose of implementing the intrinsic evolution process in a common FPGA chip and evolving a complicated digital circuit system-image filter, the design automation system employs the reconfigurable circuit architecture as the reconfigurable component of the EHW. The reconfigurable circuit architecture is inspired by the Cartesian Genetic Programming and the functional level evolution. To increase the speed of the hardware evolution, the whole evolvable hardware system which consists of evolution algorithm unit, fitness value calculation unit and reconfigurable unit are implemented by a commercial FPGA chip. The Celoxica RC1000 card which is fitted with a Xilinx Virtex xcv2000E FPGA chip is employed as the experiment platform. As the result, we conclude the terms of the synthesis report of the image filter design automation system and hardware evolution speed in the Celoxica RC1000 card. The evolved image filter is also compared with the conventional image filter form the point of filtered image quality.

• Journal of Institute of Control, Robotics and Systems
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• v.4 no.1
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• pp.113-122
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• 1998

This paper presents an implementation method of Profibus interface software using FMS(Fieldbus Message Specification). The Profibus interface software is implemented on PC which is widely used as an industrial computer as well as a commercial embedded controller called IUC(Intelligent Universal Controller). In order to enable the Profibus interface software to handle many application tasks and communication services, two kinds of real-time/multi-tasking operating system, OS-9 and CTask, are utilized. We also develop an experimental model of Profibus-based automation system, and evaluate the performance of the Profibus network. Through experiments, the user layer level message latency is measured with respect to the change of message length, message generation interval and TRT(Target Rotation Time). The results of experiment are compared with those of a simulation model which comprises only the physical and data link layers of Profibus. The results of this study shows that the message latency in the user layer level occupies fairly a large part of the total message latency.

• Journal of Information Processing Systems
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• v.14 no.1
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• pp.176-190
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• 2018

This paper presents a novel convolutional neural network based multi-feature fusion learning method for non-rigid 3D model retrieval, which can investigate the useful discriminative information of the heat kernel signature (HKS) descriptor and the wave kernel signature (WKS) descriptor. At first, we compute the 2D shape distributions of the two kinds of descriptors to represent the 3D model and use them as the input to the networks. Then we construct two convolutional neural networks for the HKS distribution and the WKS distribution separately, and use the multi-feature fusion layer to connect them. The fusion layer not only can exploit more discriminative characteristics of the two descriptors, but also can complement the correlated information between the two kinds of descriptors. Furthermore, to further improve the performance of the description ability, the cross-connected layer is built to combine the low-level features with high-level features. Extensive experiments have validated the effectiveness of the designed multi-feature fusion learning method.

• IE interfaces
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• v.7 no.2
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• pp.133-144
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• 1994

The problem of productivity improvement is one of the most challenging problems facing the world economy. This paper studies an analysis of improving personal-computer(PC) company productivity through factory automation. It attempts to analyze value added productivity at the company level. The index measured will effectively help managers supervise their companys. This study justifies that the proposed approach will stimulate manager's profit-motivation by providing them with value-oriented management instead of quantity-oriented method.