• Proceedings of the Acoustical Society of Korea Conference
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• 1996.10a
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• pp.56-60
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• 1996

본 논문에서 핵심어 검출(Keyword spotting ) 시스템에서의 채널 왜곡에 대한 보상방법등의 성능을 비교하였다. 훈련을 음성과 인식실험용 음성은 서로 다른 환경에서 수집되었으며, 특별히 인식실험용 음성으로는 전화망을 통한 음성 데이터를 이용하였다. 전화망을 통한 음성인식에서는 채널왜곡과 부가잡음에 의해서 음성신호에 왜곡이 생기므로 이들에 대한 적적한 보상이 필요하다. 본 논문에서는 채널 왜곡보상을 위한 처리방법으로 널리 사용되고 있는 global cepstral mean substraction (GCMS), local cepstral mean subtraction(LCMS) 그리고 RASTA processing을 적용하였다. 그리고 인식성능의 개선을 위해 이들 방법을 likelihood ration scorning 에 의한 후처리 과정을 적용하였다. 인식실험결과 이들 방법 모두 채널왜곡 보상을 하지 않았을 경우와 비교하여 더 좋은 인식성능을 얻을 수 있었으며, 그 중 후처리를 적용한 LCMS 방법이 가장 우수한 성능을 나타내었다.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.11b
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• pp.1145-1148
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• 2003

최근의 인터넷에서의 데이터 흐름을 보면 비대칭흐름의 경향이 있다. 비대칭흐름은 주로 하향링크의 데이터 흐름이 많은 것이 특징이며 하향링크에서 데이터흐름을 저해하는 요소인 응답(acknowledgement)을 줄여나가는 기법이 필요하다. 본 논문에서는 순방향에서의 TCP 패킷 처리율과 역방향에서의 ACK 패킷 처리율에 초점을 맞추어 수신된 패킷 순서번호를 TCP 버전별로 관찰해 보고, 실제로 처리된 패킷의 처리율로 비교 평가하였다. 시뮬레이션 결과로, 비대칭링크 유선망에서 Tahoe 버전이 Sack, NewReno보다 성능이 좋다는 것을 알 수 있었다.

• Journal of Korean Society for Geospatial Information Science
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• v.4 no.2 s.8
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• pp.137-147
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• 1996

In this paper, the performances between maximum likelihood classifier based on statistical classification and multilayer perceptrons based on neural network approaches were compared and evaluated Experimental results from both neural network method and statistical method are presented. In addition, the nature of two different approches are analyzed based on the experiments.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2000.10a
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• pp.259-265
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• 2000

This study is a fundamental research for recycling waste vinyl in asphalt concrete mixture for roadway pavement. The mixing method and proper content of waste polyethylene(PE) film were determined through preliminary mix design. This study was performed mix designs using 2 type graduations of aggregate and used two types waste PE film. The asphalt concrete mixture was satisfied with the specification of the Ministry of Construction and Transportation. Its showed that dense grade asphalt concrete mixture containing waste vinyl were higher performance in comparision to other mixtures(common dense grade mixture and gap grade mixtures). From results of this study, it was confirmed that addition of waste vinyl improved on quality of asphalt concrete mixture.

• Journal of Advanced Marine Engineering and Technology
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• v.12 no.4
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• pp.53-61
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• 1988

Speed of a diesel engine is usually controlled by the hydraulic governor which uses the centrifugal force of rotating fly balls for sensing the error speed. But for a recently developed high efficient, low speed and long stroke 2 cycle marine diesel engine, this governor doesn't work well enough because of too much changes of toraring force during one revolution of engine and too long uncontrollable time due to small numbers of cylinder. For improvement of jiggling phenomena and unstability various studies are being carried out, but they are not enough for a steep load change in a small ship's generator plant or at rough sea condition in a propulsion engine. In this paper, authors propose a new method to control a fuel before the change of angular velocity due to load change by feedforward the change of load, and find that the proposed method shows quite a good control performance in comparision to the customary PID control method by simulation using a digital computer for the various load change.

• Proceedings of the KIEE Conference
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• 2000.11b
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• pp.280-283
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• 2000

In this paper, a fault tolerant control problem is considered for a class of nonlinear system formulated in a gain scheduling form with LMI-based H-inf control technique Key benefits of this proposed scheme are demonstrated in the simulation of an electromagnetic suspension system with actuator and/or sensor failures, and the method is compared with the convensional state-feedback and output-feedback controller. It is clearly observed that the proposed control scheme shows an improved output performance in comparision with convensional methods.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.9
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• pp.62-69
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• 1996

Interpolator is a very important element in NC machines in that it controls tool path and speed. In this paper, studied were extensive interpolation characteristics of reference pulse method among various interpolation and pulse generation methods. Specifically, processing speed and path error of DDA, SPD and SFG methods were compared and analyzed against line, circle and elipse. As a result, in the point of processing speed, SPD method was found to be the best for line interpolation, SFG method for circle and ellipse, and DDA method was found to be the slowest for all paths. In the point of path error, DDA method was found to have the biggest error for all kinds of paths.

• Journal of the Korean Institute of Telematics and Electronics
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• v.24 no.1
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• pp.35-45
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• 1987

For the registration problem in which the matching of two images is made, a new algorithm using an 1-D LPC model was proposed. The proposed algorithm employed LPC coefficients as feature vector of an image. The similarity of two images was measured using an LPC distance, proposed by Itakura, between each image's feature vector. The comparision of performance with normalized correlation method and template matching method was made by a computer simulation with several real images. The results of simulation showed that the proposed algorithm was more robust to image intensity variation and computationall efficient.

• Physical Therapy Korea
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• v.6 no.1
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• pp.35-46
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• 1999

The purposes of this study were to evaluate and compare the limits of stability(LOS) at different body positioning(standing and one leg standing) in normal 20 years of age. Fourty subjects participated in the study. Subjects comprised 20 males and 20 females who without neurologic, orthopaedic impairments and balance performance impaired. The LOS was measured at Two Feet Forceplate and One Leg Forceplate with BPM(Balance Performance Monitor) Dataprint Software Version 5.3. The subjects stood 4 inches between the feet at Two Feet Forceplate and stood one legged at One Leg Forceplate. In this study applied the paired t-test and independent t-test to determine the statistical significance of results at 0.01 and 0.05 level of significance. The results of this study were as follows: 1) The anteroposterior LOS significantly increased with one legged stance(p<0.05). 2) The mediolateral LOS significantly decreased with one legged stance(p<0.01). 3) There were significant difference posterior LOS in standing and anterior LOS in one legged stance according to sexual difference(p<0.05). 4) The mediolateral LOS was not significant difference between standing and one legged stance according to sexual difference(p>0.05).

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.55 no.5
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• pp.195-201
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• 2006

Tower footing resistance and fault current division factor are important design factors for evaluation of the lightning performance of the transmission line and/or design of the grounding electrode system. The periodic measurement of those factors are also important to verify that the grounding performance of the towers has been maintained good. However, the direct measurement of those factors in operating or energized condition is very difficult because of many practical reasons, such as the difficulty of disconnecting overhead groundwires from the tower under test. With supports by GECOL (General Electricitiy Company of Libya), we had a special chance to conduct Fall-Of-Potential (FOP) test on the energized 220 kV transmission towers before and after disconnecting the overhead groundwires from the towers under test. In this paper, the FOP test results on the towers and the fault current division factors estimated from the comparision of the FOP tests with and without overhead groundwires were presented. The computer models for the FOP test simulations were also constructed to find that the simulated results agreed very well with the measured ones.