• 소음진동
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• 제9권1호
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• pp.60-69
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• 1999

In the first paper of this research$^{(1)}$. a new time series method. directional ARMAX (dARMAX) model-based approach. was proposed for rotordynamics identification. The dARMAX processes complex-valued signals, utilizing the complex modal testing theory which enables the separation of the backward and forward modes in the two-sided frequency domain and makes effective modal parameter identification possible. to account for the dynamic characteristics inherent in rotating machinery. In this second part. an evaluation of its performance characteristics based on both simulated and experimental data is presented. Numerical simulations are carried out to show that the method. a complex time series method. successfully implements the complex modal testing in the time domain. and it is superior in nature to the conventional ARMAX and the frequency-domain methods in the estimation of the modal parameters for isotropic and weakly anisotropic rotor systems. Experiments are carried out to demonstrate the applicability and the effectiveness of the dARMAX model-based approach, following the proposed fitting strategy. for the rotordynamics identification.

• 융합보안논문지
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• 제19권2호
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• pp.91-104
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• 2019

본 논문에서는 성별 인식을 위해 얼굴 영상을 효과적으로 기술하는 새로운 지역 패턴 방법 Local Prominent Directional Pattern (LPDP)를 제안한다. 제안된 LPDP 방법은 성별 인식에 중요한 얼굴 모양을 명확하게 구분하기 위해 주변 패턴이 누적된 히스토그램을 통계적으로 분석하고 패턴 변화가 크게 발생하는 픽셀을 부호화 한다. 통계적인 정보를 사용하는 얼굴 모양 구분에 중요한 뚜렷한 에지 방향 패턴 영역을 구분하는 중요한 정보를 제공 할 수 있다. 이는 뚜렷한 에지 방향 패턴이 나타나는 영역의 주변도 유사한 에지 방향 패턴이 나타내기 때문에 통계적으로 특정 방향이 히스토그램에 많이 누적될 수 있기 때문이다. 또한 통계적인 방법은 주변 영역의 정보를 많이 수용하기 때문에 잡음으로 발생하는 에지 방향 변화 오류에 강력한 장점이 있다. 제안된 방법은 기존 방법들 보다 더 강력한 성별인식에 중요한 얼굴 모양 구분 능력을 보여주면서 국소적으로 발생하는 잡음에 견고함을 보여준다. 우리는 제안된 방법의 성능을 평가하기 위해 밝기, 표정, 연령, 머리 포즈가 변화하는 성별 인식 데이터 셋에 다양한 실험을 실험 했고 기존 방법 보다 제안된 방법의 성능이 우수함을 입증했다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문초록집
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• pp.385.1-385
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• 2002

Operational Modal Analysis also known as Ambient Modal Analysis has an increasing interest in mechanical cngineering. Especially on big structures where the excitation and not less important the determination of the forces is most often a problem. In a structure like a wind turbine wing where the modes occur both close in frequency and bi-directional the Ambient excitation has big advantages. (omitted)

• Journal of Communications and Networks
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• 제11권5호
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• pp.433-444
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• 2009

The bi-directional relay channel is the natural extension of a three-terminal relay channel where node a transmits to node b with the help of a relay r to allow for two-way communication between nodes a and b. That is, in a bi-directional relay channel, a and b wish to exchange independent messages over a shared channel with the help of a relay r. The rates at which this communication may reliably take place depend on the assumptions made on the relay processing abilities. We overview information theoretic limits of the bi-directional relay channel under a variety of conditions, before focusing on half-duplex nodes in which communication takes place in a number of temporal phases (resulting in protocols), and nodes may forward messages in four manners. The relay-forwarding considered are: Amplify and forward (AF), decode and forward (DF), compress and forward (CF), and mixed forward. The last scheme is a combination of CF in one direction and DF in the other. We derive inner and outer bounds to the capacity region of the bi-directional relay channel for three temporal protocols under these four relaying schemes. The first protocol is a two phase protocol where a and b simultaneously transmit during the first phase and the relay r alone transmits during the second. The second protocol considers sequential transmissions from a and b followed by a transmission from the relay while the third protocol is a hybrid of the first two protocols and has four phases. We provide a comprehensive treatment of protocols in Gaussian noise, obtaining their respective achievable rate regions, outer bounds, and their relative performance under different SNR and relay geometries.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2018년도 춘계학술대회
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• pp.484-486
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• 2018

최근 다양한 분야에서 디지털 장비의 사용이 증가함에 따라 영상 및 신호처리의 중요성이 높아지고 있다. 하지만 디지털 신호는 송수신 과정에서 많은 종류의 잡음이 발생하며 고장의 원인이 되고 있다. 이러한 이유로 여러 분야에서 잡음 제거를 전처리 과정으로서 필수적으로 행한다. 본 논문은 임펄스 잡음과 AWGN이 혼합된 잡음을 제거하기 위해 잡음 판단을 통해 잡음을 구분하여 잡음 제거를 진행한다. 그리고 잡음 종류에 따라 변형된 가우시안 필터와 방향성 유효 화소를 이용하여 처리하는 알고리즘을 제안하였다. 시뮬레이션 결과 우수한 잡음제거 특성을 나타내었으며, 객관적인 판단을 위해 기존 방법들과 비교하였다.

• 한국소음진동공학회논문집
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• 제21권6호
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• pp.521-528
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• 2011

A variety of noise control methods have been developed as an interest on noise issues increases. Among them, noise control methods using masking effect, a phenomenon to reduce the ability to notice the unwanted sound by proper sound, to implement a pleasant sound environment have been studied under the name of soundscape. We proposed a novel vector base amplitude panning(VBAP) based noise control method to apply to the building environment. The proposed method could improve the amenity inside the building to reproduce the sounds with excellent masking effect on the incoming path of noise using the control speakers, considering the direction of noise source. The directional masking sounds can be generated by using VBPA technique. To verify the performance of the proposed method, we carried out the subjective test for the degree of amenity according to direction of the masking sound. Subjective test results showed that it is possible to improve the amenity inside the building by controlling the direction of masking sound considering the human's auditory characteristic.

• 한국음향학회:학술대회논문집
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• 한국음향학회 1999년도 학술발표대회 논문집 제18권 1호
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• pp.202-205
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• 1999

• 대한의용생체공학회:의공학회지
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• 제25권1호
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• pp.83-86
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• 2004

The variation of the directional properties of an image is used to extract the iris code for human identification. In order to conserve the original information while minimizing the effect of noise, scale-space filtering is applied. Resulting binary codes have been tested on a set of 272 iris images obtained from 18 persons.

• 한국소음진동공학회논문집
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• 제24권7호
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• pp.569-574
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• 2014

In order to investigate low frequency swishing noise of wind turbines, acoustic source model using a singularity in circular motion is introduced to derive analytic solution of Lowson acoustic analogy in time domain. Results in time and frequency domains computed by the solution show apparent modulation of amplitude and frequency. The solution indicates that time histories of acoustic pressure at receiver points varied significantly according to receiver's directional location, even when the retarded time distributions are similar. However, the corresponding time-averaged spectra of sound pressure at the receiver locations where the retarded time distributions are almost same are not significantly different. It can be inferred from these results that the time-averaged sound pressure spectra which cannot take into account the detailed difference in the time-variation of wind turbine noise may not represent the sound quality of wind turbines due to its swishing. Finally, as an introduction of procedure to quantify low frequency swishing noise level, relative variation of overall sound pressure level is obtained using tonal low frequency noise model.

• 한국소음진동공학회논문집
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• 제16권1호
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• pp.81-88
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• 2006

The most recent trend on digital hearing aid is to increase the ratio of signal to noise by directivity or to develop noise reduction algorithm inside DSP IC chip. This paper designed, fabricated and tested a digital hearing aid directivity testing device in which a micro-mouse-like the stepping motor with a speaker rotates around an examinant. Both ears of the examinant were fixed with ITE hearing aids in order to respond to receiving sound. The experimental results were compared with those of a boundary element method program for verification. The diameter of the directivity testing device was 2 m and the micro-mouse was precisely controlled by PICBASIC micro processor.