• Proceedings of the IEEK Conference
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• 2000.07a
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• pp.466-469
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• 2000

In this paper, a watermarking technique for digital images is proposed. In our method, an image is 1-1eve1 wavelet transformed, and then the watermark of a binary stamp is embedded into the baseband. The watermark is embedded by inverting the polarities of the selected coefficient pairs. In the inverting process, we can increase perceptual image quality by finding means and differences of the selected neighboring coefficient pairs, and then adding values, which are inversely proportional to the differences, to the means. The experimental results show that the proposed method has good quality and is robust to JPEG lossy compression and various image processing operations.

• Proceedings of the KOR-BRONCHOESO Conference
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• 1978.06a
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• pp.9.1-10
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• 1978

Recently the authors have observed various wave-forms by insertion of induction coil into the scala tympani as well as attached outer device in the outside of the body in damaged hair cells of the cats. In the cochlear nerve. action potential indicated different polarities induced by examination of the bundle of the cochlear nerve fibers. Impulse wave-form as a result of excitation of cohlear nerve fibers showed bipolar wave-form such as negative 1 and positive 1. Therefore action potential showed also bipolar wave-form as above mentioned. We can obtained suitable response with above mentioned outer and inner device as an exact oscillogram.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.6 s.121
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• pp.648-655
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• 2007

In this paper, we introduce a dual coil antenna which is useful for reducing the effects of radio frequency noise in an RFID system. A dual coil antenna is composed of two identical coils that are connected in series. The noise voltages in the two coils almost disappear when they are added because the magnitudes are equal and the polarities are opposite. The noise in an RFID reader with a dual coil antenna was 15 dB lower than that with a single coil antenna.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.480-483
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• 1997

This paper describes dielectric characteristics and discharge development mechanisms of SF$_{6}$ gas stressed by very fast transient overvoltages in inhomogeneous electric field. Predischarge phenomena of SF$_{6}$ gas in non-uniform fields are statistically investigated with positive and negative very fast trannsient overvoltages. It was confirmed that all of the predischarges of the positive and negative polarities develop in a regime of stepwise leader extension. i.e, the predischarge developments leading to breakdown against very fast transient overvoltages are similar to the non-oscillating impulse voltages.ges.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.254-255
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• 2007

This paper describes underwater discharge phenomena which are less studied than gas, solid and dielectric liquid. Since discharge phenomena were affected by various factors, we investigated the effect of water resistivity in point-plane gap by impulse voltage. In discharge photograph, it is hard to discover the streamer development in positive polarity at high reisistivity. On the other hand, the streamer originated at the tip of rod and developed toward the plane with increasing voltage. It is found that the breakdown voltage of both polarities in lower resistivity are lower than that of high resistivity. High current flowing in lower resistivity before the breakdown induce more streamer and enhance the probability of breakdown.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.8
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• pp.1311-1317
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• 2008

In this paper, a fault location algorithm using wavelet transform is proposed for HVDC cable lines. The arriving instants of the first and second fault-induced backward travelling waves can be detected by using wavelet transform. The fault distance is estimated by using the time difference between the two instants of backward travelling waves and the velocity of the travelling wave. To distinguish between the backward wave from fault point and the backward wave from the remote end, polarities of backward waves are used. The proposed algorithm is verified varying with fault distances and fault resistances in underground cables of VSC(voltage source converter) HVDC system and CSC(Current Source Converter) HVDC respectively. Performance evaluations of the proposed algorithm shows that it has good ability for a fault location of HVDC cable faults.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1455-1456
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• 2007

This paper presents the experimental results on impulse breakdown characteristics under a highly non-uniform electric field in $SF_{6}/N_{2}$ gas mixtures according to a change in temperature. Test temperature ranges from $-25^{\circ}C$ to $25^{\circ}C$. The impulse predischarge breakdown developments are investigated by the measurements of current pulse and discharge luminous events. As a result, the predischarge development mechanisms for both positive and negative polarities are same. When increasing the temperature, breakdown voltage due to lightning impulse voltage is increased in negative polarity. On the other hand, when increasing the temperature, breakdown voltage due to lightning impulse voltage is not changed in positive polarity.

• Proceedings of the Korea Information Processing Society Conference
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• 2014.04a
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• pp.745-748
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• 2014

SentiWordNet is an important lexical resource supporting sentiment analysis in opinion mining applications. In this paper, we propose a novel approach to construct a Vietnamese SentiWordNet (VSWN). SentiWordNet is typically generated from WordNet in which each synset has numerical scores to indicate its opinion polarities. Many previous studies obtained these scores by applying a machine learning method to WordNet. However, Vietnamese WordNet is not available unfortunately by the time of this paper. Therefore, we propose a method to construct VSWN from a Vietnamese dictionary, not from WordNet. We show the effectiveness of the proposed method by generating a VSWN with 39,561 synsets automatically. The method is experimentally tested with 266 synsets with aspect of positivity and negativity. It attains a competitive result compared with English SentiWordNet that is 0.066 and 0.052 differences for positivity and negativity sets respectively.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.03a
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• pp.16-22
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• 2003

The focal mechanisms of the earthquakes occurred in 2001 and 2002 are analyzed to understand the regional stress and tectonics in and around Korean Peninsula. The forty -three fault plane solutions are derived using the polarities of first arrival P-waves recorded at KIGAM, Bmh and KEPRI stations. The result suggest that thrust motion with significant amount of strike slip component is dominant mode of faulting. The larger population of mechanism is characterized by WNW-ESE striking nodal planes. NE-SW direction is interpreted as dominant compressional axis orientation of stress field. These solutions are similar to those of medium size earthquakes studied previously, which is known as typical regional tectonic stress orientation in and around Korean Peninsula.

• Journal of Industrial and Engineering Chemistry
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• v.68
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• pp.282-292
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• 2018

This study aimed to compare the chemical composition of Morus nigra leaves extracts, obtained by maceration, accelerated solvent (ASE) and supercritical fluid extraction (SFE) under different extraction conditions. With regards to chemical composition, mainly phenolic acids and flavonoids were identified. HPLC-ESI-QTOF-MS allowed the identification of 13 new compounds reported in M. nigra leaves for the first time. ASE as a fast, green and innovative approach, seems to be the best choice for extracting compounds of different polarities within the shortest extraction time. The present study also highlights the potential application of M. nigra extracts as constituents of new added-value formulations.