• 동력기계공학회지
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• 제5권4호
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• pp.44-52
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• 2001

This paper considers a modeling and identification for the MIMO magnetic bearing system. To obtain the nominal plant transfer functions, we have experimented on the frequency response by a closed-loop identification method because the system is unstable essentially. We suggest a method of curve-fitting for obtaining the transfer function from the frequency responses by using the system's modeling structure and two controllers which are different from each other. From the frequency response results, we found the effects of coupling by opposing controllers. And using this effects and the system's modeling structure, we could obtain the transfer functions of which have the same modularized denominators.

• 비파괴검사학회지
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• 제23권6호
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• pp.559-565
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• 2003

A spectral element model-based structural damage identification method (SDIM) was derived in the previous study by using the damage-induced changes in frequency response functions. However the previous SDIM often provides poor damage identification results because the nonlinear effect of damage magnitude was not taken into account. Thus, this paper improves the previous SDIM by taking into account the nonlinear effect of damage magnitude. Accordingly an iterative solution method is used in this study to solve the nonlinear matrix equation for local damages distribution. The present SDIM is evaluated through the numerically simulated damage identification tests.

• Journal of Magnetics
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• 제20권3호
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• pp.295-301
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• 2015

We evaluated certain issues related to magnetic resonance imaging (MRI) coupled with the use of active 2.5 GHz radio frequency identification (RFID) tags for patient identification using low field (0.3 T) MRI and computed tomography (CT) scans. We also investigated the performance of the RFID reader located outside the MRI room by considering several factors. A total of ten active RFID tags were exposed to several MRI sequences and X-rays of CT scan. We found that only card type active RFID tags are suitable for patient identification purpose in MRI environment and both wristbands as well as card tags were suitable for the same in CT environment. Severe artifacts were found in the captured MRI and CT images when the area of the imaging was in proximity to the tags. No external factors affected the performance of active RFID reader stationed outside the MRI scan room.

• 한국통신학회:학술대회논문집
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• 한국통신학회 2004년도 추계종합학술대회 논문 초록집
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• pp.413-413
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• 2004

• 한국HCI학회:학술대회논문집
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• 한국HCI학회 2008년도 학술대회 1부
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• pp.190-194
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• 2008

본 논문은 지능형 서비스 로봇의 여러 기술들 중에서 기본적인 기술인 화자식별 기술에 관한 내용이다. 화자식별 기술은 화자의 음성신호를 이용하여 등록된 화자들 중에서 가장 유사한 화자를 찾아내는 것이다. 기존의 mel-frequency cepstral coefficient 를 이용한 화자식별 시스템은 무잡음 환경에서는 높은 성능을 보장하지만 잡음환경에서는 성능이 급격하게 떨어진다. 이렇게 잡음환경에서 성능이 떨어지는 요인은 등록환경과 식별환경이 다른 불일치문제 때문이다. 본 논문에서는 불일치문제를 해결하기 위해 relative autocorrelation sequence mel-frequency cepstral coefficient 를 사용하였다. 또한, 기존의 relative autocorrelation sequence mel-frequency cepstral coefficient 의 제한된 정보문제와 잔여잡음문제를 해결하기 위해 멀티스트리밍 방법과 멀티스트리밍 방법에 특정벡터 재결합 방법을 결합한 하이브리드 방법을 제한 하였다. 실험결과 제한된 방법들이 기존의 특정벡터보다 잡음환경에서 높은 화자식별 성능을 보여주었다.

• 한국해양공학회지
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• 제24권1호
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• pp.123-132
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• 2010

This paper presents a prestress-loss monitoring technique for prestressed concrete (PSC) girder structures that uses a vibration-based system identification method. First, the theoretical backgrounds of the prestress-loss monitoring technique and the system identification technique are presented. Second, vibration tests are performed on a lab-scaled PSC girder for which the modal parameter was measured for several prestress-force cases. A numerical modal analysis is performed by using an initial finite element (FE) model from the geometric, material, and boundary conditions of the lab-scaled PSC girder. Third, a vibration-based system identification is performed to update the FE model by identifying structural parameters since the natural frequency of the FE model became identical to the experimental results. Finally, the feasibility of the prestress-loss monitoring technique is evaluated for the PSC girder model by using the experimentally measured natural frequency and numerically identified natural frequency for several prestress-force cases.

• 한국수산과학회지
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• 제49권2호
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• pp.224-233
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• 2016

The objective of this study was to develop an artificial neural network (ANN) model for the acoustic identification of commercially important fish species in Korea. A broadband echo acquisition and processing system operating over the frequency range of 85-225 kHz was used to collect and process species-specific, time-frequency feature images from six fish species: black rockfish Sebastes schlegeli, black scraper Thamnaconus modesutus [K], chub mackerel Scomber japonicus, goldeye rockfish Sebastes thompsoni, konoshiro gizzard shad Konosirus punctatus and large yellow croaker Larimichthys crocea. An ANN classifier was developed to identify fish species acoustically on the basis of only 100 dimension time-frequency features extracted by the principal components analysis (PCA). The overall mean identification rate for the six fish species was 88.5%, with individual identification rates of 76.6% for black rockfish, 82.8% for black scraper, 93.8% for chub mackerel, 90.6% for goldeye rockfish, 96.9% for konoshiro gizzard shad and 90.6% for large yellow croaker, respectively. These results demonstrate that individual live fish in well-controlled environments can be identified accurately by the proposed ANN model.

• Structural Engineering and Mechanics
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• 제84권3호
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• pp.413-421
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• 2022

Modal parameters are the main dynamic characteristics of bridge. This study aims to propose an innovative route to estimate the modal parameters for bridges by using a parked vehicle in which mode shapes with high accuracy and spatial resolution are identified by frequency measurement. Based on the theory of dynamic modification and modal identification, the mathematical formulation between the parked mass induced frequency variation and the modal parameters of a bridge is derived. Then this mathematical formulation is extended to a parked vehicle-bridge system. The arithmetic and processes for estimating the modal parameters based on the identified frequency variation of the vehicle-bridge systems when the vehicle locates at sequentially arranged positions are presented. Finally the proposed method is applied to several simulated bridges of different types. The results indicate that it can estimate the modal parameters with high accuracy and efficiency.

• 한국수정란이식학회지
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• 제9권2호
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• pp.197-205
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• 1994

This experiment was carried out to clarify the pedigree identification from blood typing of 301 Hoisteins in National Animal Breeding Institute(N.A.B.I.). Twenty kinds of standard reagent standardized by Insternational Society for Animal Blood Group Research provied from KNC improvement center, N, L, C, F. were used as the reference reagents in this study. The highest frequency of antigenic facfors was obtained from X$_2$in blood typing of 301 Holsteins. The frequency of X$_2$ was 0.714.In A blood system, four kinds of phenogroups were observed. The gene frequencies of Al and Z' phenogroups were equally 0.027.This frequency was greatly lower than those of breeds of Southern European and Zebu cattle. In B blood Systern, nineteen kinds of blood type were appeared. The appearance frequency of Gx blood type was 0.259, whish was higher than the others. In C blood system, thirty kinds of blood type were observed. The appearance frequency of X$_2$ blood type was the highest(0.189). In F blood system, three kinds of alleles were detected. The gene frequency of F allele was higher than that of V(0.105). However, the frequency of F allele(0.327) was greatly lower than that of "- /- " allele. In S blood system, twelve kinds of blood type were appeared and showed sirnilar appearance frequencies except " - / - " allele. From the results of the pedigree identification from 8 sires and 28 progenies of them, the accuracy of pedigree identification was 92.9%.ification was 92.9%.

• 한국산학기술학회논문지
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• 제10권12호
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• pp.3608-3613
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• 2009

본 논문에서는 휴대용 단말기 적용이 가능한 mobile Radio Frequency Identification (m-RFID) system 을 위한 안테나의 설계 방법을 제안했다. 전기계 안테나와 자기계 안테나의 결합을 통하여 안테나의 휴대 단말 장착시 m-RFID 적용 방향으로 안테나의 패턴이 지향성의 특징을 나타낸다. 전기계 안테나는 PIFA 구조의 안테나를 사용하였으며, 자기계 안테나는 loop 형 안테나를 구현하였다. 목표 주파수 대역은 900 MHz 대역이며, 목표 이득은 4dBi 이상으로 설계 되었다. Ansoft 사의 HFSS 를 사용하여 시뮬레이션하였으며, 목표치 이상의 결과를 보였다. 제작된 안테나는 FR4 epoxy 기판 (h=1 mm, $\varepsilon_{\tau}=4.4$) 을 사용하여 제작되었으며, 시뮬레이션과 유사한 결과를 보였다.