• International Journal of Fuzzy Logic and Intelligent Systems
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• 제15권3호
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• pp.159-165
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• 2015

The need for the recognition of music emotion has become apparent in many music information retrieval applications. In addition to the large pool of techniques that have already been developed in machine learning and data mining, various emerging applications have led to a wealth of newly proposed techniques. In the music information retrieval community, many studies and applications have concentrated on tag-based music recommendation. The limitation of music emotion tags is the ambiguity caused by a single music tag covering too many subcategories. To overcome this, multiple tags can be used simultaneously to specify music clips more precisely. In this paper, we propose a novel technique to rank the proper tag combinations based on the acoustic similarity of music clips.

• 한국소음진동공학회논문집
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• 제24권7호
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• pp.555-561
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• 2014

Acoustic Emission technique is widely applied to develop the early fault detection system, and the problem about a signal processing method for AE signal is mainly focused on. In the signal processing method, envelope analysis is a useful method to evaluate the bearing problems and wavelet transform is a powerful method to detect faults occurred on rotating machinery. However, exact method for AE signal is not developed yet for the rotating machinery diagnosis. Therefore, in this paper two methods which are processed by Hilbert transform and DET for feature extraction. In addition, we evaluate the classification performance with varying the parameter from 2 to 15 for feature selection DET, 0.01 to 1.0 for the RBF kernel function of SVR, and the proposed algorithm achieved 94 % classification of averaged accuracy with the parameter of the RBF 0.08, 12 feature selection.

• 한국정보과학회논문지:소프트웨어및응용
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• 제29권3호
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• pp.167-179
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• 2002

본 논문에서는 여러 프레임 특징으로 표현되는 분절 특징(segmental feature) 표현 방법을 제안하고, HMM 개념 위에서 음향학적 모델과 그 알고리즘을 개발하여 HMM의 약점으로 지적되는 독립관측 가정을 완화시키고자 한다. 제안된 특징 표현은 단일 프레임 특징이 음성 신호의 시간적 동적 특성 (temporal dynamics)을 제대로 표현하지 못하기 때문에, 여러 프레임을 이용하여 음성 특징을 표현하도록 한다. 분절 특징은 다항식의 회귀 함수(polynomial regression function)에 의하여 관측 벡터의 궤적으로 표현되고, 이 특징을 패턴 분류에 사용하기 위하여 음성 신호의 궤적을 효과적으로 표현하는 분절 HMM(segmental HMM)을 이용한다. SHMM은 상태에서의 관측 확률을 외적 분절 변이와 내적 분절 변이로 세분하며, 외적 분절 변이는 장기적인 변화를, 내적 분절 변이는 단기적인 변화를 나타낸다. 음향학적 모델에서 분절 특성을 고려하기 위하여 외적 분절 변이는 분절의 확률 분포로 표현하고, 내적 분절 변이는 궤적의 추정 오차로 표현하도록 SHMM을 수정한 분절 특징 HMM(SFHMM; segmental-feature HMM)을 제안한다. SFHMM에서는 분절의 관측 확률을 분절 우도와 궤적의 추정 오차의 관계로써 표현하며, 추정오차는 특정 상태에서의 분절의 우도에 대한 가중치로 고려될 수 있다. 제안된 방법의 유효성과 분절 특징의 특성을 살펴보기 위하여 TIMIT 자료를 이용하여 몇 가지 실험을 하였다. 이들 실험 결과에서, 제안된 방법이 기존의 HMM보다 매개 변수가 많더라도, 성능의 향상과 제안된 특징이 유연하고 정보를 많이 가진다는 점에서 의미가 있다고 하겠다.

• 대한의용생체공학회:의공학회지
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• 제11권2호
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• pp.289-294
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• 1990

In this paper, for acoustic source reconstruction using angular frequency propagation method, the extended Prony method is propsed which is useful due to not having the inherent property of DFT. The simulation is carried out and its improved results are shown explicitly by comparing with DFT case.

• 비파괴검사학회지
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• 제33권1호
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• pp.7-13
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• 2013

철강 생산 제품 중 강선 (steel wire rod)은 제조 과정 중 종방향으로 미세한 표면 결함이 매우 빈번하게 발생하는데 이중 깊이가 수 십 마이크로미터 이상인 결함들은 최종 생산품의 불량을 유발하는 심각한 원인이 되고 있다. 이와 같은 이유로 강선의 제조 단계에서 표면의 미세 결함의 깊이를 평가하는 방법의 개발이 절실히 요구된다. 표면 미세 결함을 평가할 수 있는 여러 가지 방법 중에서, 본 연구에서는, 전자기 음향공진법의 적용 가능성을 고찰하고자 한다. 전자기 음향 공진 (electromagnetic acoustic resonance, EMAR)은 전자기 음향 트랜스듀서 (electromagnetic acoustic transducer, EMAT)을 이용하여 시편의 공진 특성을 측정하는 방법으로서, 대상의 작은 변화에도 민감하게 반응하고 비접촉 측정이 가능하여 현장 적용에 용이하다는 장점이 있다. 전자기 음향 공진 실험을 통하여 표면 미세결함과 잔향특성의 변화를 관찰하여 깊이 약 100 마이크로미터 내외의 결함은 탐상 가능함을 확인하였다.

• Ocean Science Journal
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• 제42권1호
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• pp.1-8
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• 2007

Acoustic volume backscattering strength data were collected and Conductivity Temperature Depth (CTD) measurements were conducted in the southern Yellow Sea in summer 2005 and 2006. The high temporal and vertical resolution acoustic data measured with a 307 kHz Acoustic Doppler Current Profiler (ADCP) and a 250 kHz acoustic Doppler profile (ADP) had dominant diel variation, which resulted from vertical migration of sound scatterers. Some scatterers congregating in the bottom layer in the daytime migrated upward at dusk, and migrated downward into the bottom layer at dawn. The migration speeds were estimated. More than 33 days data show that the diel migration varies with time. The feature of migration measured with ADCP and ADP is consistent to some extent with what is described in the study on vertical migration of zooplankton in the southern Yellow Sea with conventional net samples.

• 한국소음진동공학회논문집
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• 제22권8호
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• pp.742-747
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• 2012

A modified NDIF method using a sub-domain approach is introduced to extract highly accurate eigenvalues of two-dimensional, arbitrarily shaped acoustic cavities. The NDIF method, which was developed by the authors for the eigen-mode analysis of arbitrarily shaped acoustic cavities, has the feature that it yields highly accurate eigenvalues compared with other analytical methods or numerical methods(FEM and BEM). However, the NDIF method has the weak point that it can be applicable for only convex cavities. It was revealed that the solution of the NDIF method is very inaccurate or is not suitable for concave cavities. To overcome the weak point, the paper proposes the sub-domain method of dividing a concave domain into several convex domains. Finally, the validity of the proposed method is verified in two case studies, which indicate that eigenvalues obtained by the proposed method are more accurate compared to the exact method, the NDIF method, or FEM(ANSYS).

• 한국멀티미디어학회논문지
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• 제13권4호
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• pp.496-503
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• 2010

어휘인식 시스템은 스탠드 얼론(Standalone)으로 개발되어 지고 있으며 휴대용 단말기에서 사용하였을 경우 메모리 공간의 제약과 오디오 압축으로 인해 인식률이 낮게 나타난다. 본 연구에서는 휴대용 단말기의 성능과 인식률 향상을 위하여 음향학적 탐색과 언어적 탐색을 분리하여 어휘 인식 속도를 개선한 시스템을 제안하였다. 음향학적 탐색은 휴대용 단말기에서 수행하고 보다 복잡한 언어적 탐색은 서버에서 처리하는 시스템으로 음성신호로부터 특징벡터를 추출하여 GMM을 이용한 음소인식을 수행하고, 인식된 음소 열을 서버로 전송하여 렉시컬 트리 탐색 알고리즘을 사용하여 언어적 탐색 단계에서 어휘 인식을 수행하였다. 시스템 성능 평가 결과 어휘 종속 인식률은 98.01%, 어휘 독립 인식률은 97.71%의 인식률을 나타냈으며 인식속도는 1.58초로 나타내었다.

• The Journal of the Acoustical Society of Korea
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• 제16권2E호
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• pp.3-13
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• 1997

The Jing is a traditional Korean percussion instrument which plays a major role in Korean folk music. The distingishing feature of this instrument is its unique, long lasting low tone timbre. In this paper, we investigated the vibro-acoustic characteristics of the Jing. Our attention was focused mainly on findings out the physical variables that determine its unique sound. By understanding the way in which the Jing is manufactured, we were able to realize that the unique manufacturing and especially the tuning process by expert craftsman is responsible for the peculiar timbre the Jing produces. The experimental methods implemented to analyzer the Jing were planar acoustic holography and direct measurements by accelerometers. The results from the holographic method and the direct measurements were in good agreement. It turned out that unlike most percussion instruments which have inharmonic partials, the Jing has harmonic partials which are responsible for its unique low-tone timbre. From the holographic representations of the modes, it is clear that the antinodes are located in the center of the Jing which is coincident with the typical striking location. In addition, intensity maps were constructed so that the specific acoustic energy flow can be visualized. It was also interesting to see the the circulation of energy intensity which corresponds to the rotating mode of the Jing.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 추계학술대회 논문집
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• pp.124-129
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• 2011

An improved NDIF method is introduced to efficiently extract eigenvalues of two-dimensional, arbitrarily shaped acoustic cavities. The NDIF method, which was developed by the authors for the eigen-mode analysis of arbitrarily shaped acoustic cavities, membranes, and plates, has the feature that it yields highly accurate eigenvalues compared with other analytical methods or numerical methods (FEM and BEM). However, the NDIF method has the weak point that the system matrix of the NDIF method depends on the frequency parameter and, as a result, a final system equation doesn't take the form of an algebra eigenvalue problem. The system matrix of the improved NDIF method developed in the paper is independent of the frequency parameter and eigenvalues can be efficiently obtained by solving a typical algebraic eigenvalue problem. Finally, the validity and accuracy of the proposed method is verified in two case studies, which indicate that eigenvalues and mode shapes obtained by the proposed method are very accurate compared to the exact method, the NDIF method or FEM(ANSYS).