• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.58-62
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• 2001

Photovoltaic and wind power generation have an advantage of unlimited and unpolluted amount of energy resource. In conventional wind generation systems, since the blade rotates at low speed when the velocity of wind decreases their operations are possible only under limited conditions. Therefore they are in trouble of self-generation without the help of auxiliary generation devices outside. The system driven by the wind force in this paper consists of a generator, an invertor, batteries and sets for power storage with a spring. In this paper, the operation characteristics of system were analyzed through experiments for a trial product.

• Journal of Information Processing Systems
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• v.11 no.3
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• pp.354-369
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• 2015

Recently, there has been an increasing demand of high data rates services, where several multiuser multiple-input multiple-output (MU-MIMO) techniques were introduced to meet these demands. Among these techniques, vector perturbation combined with linear precoding techniques, such as zero-forcing and minimum mean-square error, have been proven to be efficient in reducing the transmit power and hence, perform close to the optimum algorithm. In this paper, we review several fixed-complexity vector perturbation techniques and investigate their performance under both perfect and imperfect channel knowledge at the transmitter. Also, we investigate the combination of block diagonalization with vector perturbation outline its merits.

• Journal of Information Processing Systems
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• v.11 no.4
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• pp.643-654
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• 2015

Face recognition under controlled settings, such as limited viewpoint and illumination change, can achieve good performance nowadays. However, real world application for face recognition is still challenging. In this paper, we propose using the combination of Affine Scale Invariant Feature Transform (SIFT) and Probabilistic Similarity for face recognition under a large viewpoint change. Affine SIFT is an extension of SIFT algorithm to detect affine invariant local descriptors. Affine SIFT generates a series of different viewpoints using affine transformation. In this way, it allows for a viewpoint difference between the gallery face and probe face. However, the human face is not planar as it contains significant 3D depth. Affine SIFT does not work well for significant change in pose. To complement this, we combined it with probabilistic similarity, which gets the log likelihood between the probe and gallery face based on sum of squared difference (SSD) distribution in an offline learning process. Our experiment results show that our framework achieves impressive better recognition accuracy than other algorithms compared on the FERET database.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.742-743
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• 2007

A maintenance plan of power system equipment reduces failure rate caused by equipment's age. To prevent unexpected failure, the maintenance is performed periodically according to the interval time. The more expansive equipment's scale is, the more the maintenance without considering costs sustains a economical loss. Hence, the maintenance's time and the cost must be considered when maintenance which is considering the reliability is implemented. In this paper, optimum maintenance interval is calculated by considering minimum maintenance cost of the equipment with the combined cycle units in Korea power systems.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.612-613
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• 2007

The line impedance is important data that are applied in all analysis fields of electric power system such as power flow, fault current, stability and relay calculation etc. Usually, the impedance can be accurately calculated in case of overhead line. However, in case of power cables or combined transmission lines, the impedance can not be accurately calculated because cable systems have the sheath, grounding wires, and earth resistances. Therefore, if there is a fault in cable system, these terms will severely be caused many errors for calculating impedance. In this paper, the line impedance is measured in a power system of underground cables, and is analyzed by a generalized circuit analysis program, EMTP(Electromagnetic Transient Program), for comparison with the measured value. These analysis results are considered to become foundation of impedance calculation for underground cables.

• Industrial Engineering and Management Systems
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• v.7 no.1
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• pp.66-77
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• 2008

The existence of Internet revolutionized the computer and communications world. With the rising demand for accessing the Internet, the mobile technology has incorporated the use of Internet in mobile phones. Wireless Application Protocol (WAP) has combined two of the widest utilized technology today: mobile phones and Internet. This study aims to assess the existing WAP pages offered by the top service providers in the Philippines through usability testing experiments. The paper also aims to identify existing problems in WAP interface by focusing on the errors committed by the users. From the usability study, it was found out that common usability problems are wrong selection of links, unclear grouping of categories, wrong feedback, and redundant links. The type of service provider used is significant in determining the performance of users while experience in accessing WAP is insignificant.

• Journal of Information Processing Systems
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• v.14 no.3
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• pp.727-739
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• 2018

This study evaluates the viewpoints of user focus incidents using microblog sentiment analysis, which has been actively researched in academia. Most existing works have adopted traditional supervised machine learning methods to analyze emotions in microblogs; however, these approaches may not be suitable in Chinese due to linguistic differences. This paper proposes a new microblog sentiment analysis method that mines associated microblog emotions based on a popular microblog through user-building combined with spectral clustering to analyze microblog content. Experimental results for a public microblog benchmark corpus show that the proposed method can improve identification accuracy and save manually labeled time compared to existing methods.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.1
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• pp.99-103
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• 2012

The electromagnetic topology and the BLT equation has been used as useful techniques to analyze coupling effects of huge devices. But in the case of systems including complex parts, applying the BLT equation can be difficult to manifest the complex parts with analytic solutions. To resolve this problem, a numerical method can be used to parts of the whole system in advance. In this paper, a microstrip line filter is analyzed using the BLT equation combined with numerical solutions. Consequently, achieved graphs from the BLT equation show good agreements with graphs obtained using a numerical method only.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.785-788
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• 2003

Many application in robotics, telecommunication, automation systems etc require powerful actuator. The powerful actuator have Speeds up to high speed and high output torque efficiencies. To accomplish a powerful actuator, these powerful motor have to be combined with gearheads of the same outer diameter. So, we have developed BLDC motor and planetary type gearheads as powerful actuator. The BLDC motor have advantages that compact structure, high efficiency, high reliability. The Planetary type gearheads have advantages that same-axle structure, high torque transmission, low noise in comparison with spur gearheads. In this study included BLDC motor and planetary type gearheads design, manufacture. This time study performed for actuator of precision mechanism.

• KSTLE International Journal
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• v.8 no.2
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• pp.26-28
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• 2007

Si(100) surfaces were topographically modified i.e. the surfaces were patterned at micro-scale using photolithography and DRIE (Deep Reactive Ion Etching) fabrication techniques. The patterned shapes included micro-pillars and microchannels. After the fabrication of the patterns, the patterned surfaces were chemically modified by coating a thin DLC film. The surfaces were then evaluated for their friction behavior at micro-scale in comparison with those of bare Si(100) flat, DLC coated Si(100) flat and uncoated patterned surfaces. Experimental results showed that the chemically treated (DLC coated) patterned surfaces exhibited the lowest values of coefficient of friction when compared to the rest of the surfaces. This indicates that a combination of both the topographical and chemical modification is very effective in reducing the friction property. Combined surface treatments such as these could be useful for tribological applications in miniaturized devices such as Micro-Electro-Mechanical-Systems (MEMS).