• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1998년도 춘계학술대회논문집; 용평리조트 타워콘도, 21-22 May 1998
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• pp.75-80
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• 1998

Statistical Energy Analysis(SEA) has been considered as a possible method for predicting responses of complex structures, especially at higher frequencies. In this paper, an SEA model of vehicle was built using 138 energy storing subsystems connected together using 1019 junctions. SEAM software program was used to build and calculate the model. To demonstrate the accuracy of the SEA model, predicted response levels were compared with measured levels. The source input levels were measured at the engine mounting parts. For the vibration levels, the agreement between the calculation results and the experimental ones was found to be good. The energy flow between connected subsystems can be presented, because the analysis method is based on the estimation of the power flow between subsystems. This paper also identifies some dominant energy flow paths from sources. It is finally presented that the SEA model can optimize the design parameters of vehicles using model parameters and energy flow paths.

• 한국자기학회지
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• 제4권2호
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• pp.142-149
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• 1994

두께가 0.30 mm, 0.27 mm인 3% 방향성 규소강판에서 표면 선긋기의 간격(39~1.22 mm)과 집합조직(texture) 방향에 대한 선긋기 각도의 변화($90^{\circ}~50^{\circ}$)에 따라 Barkhausen Noise를 측정하였다. 두께 0.27 mm의 시편에서 선긋기를 하지 않았을 때와 선긋기의 간격이 39 mm인 경우 에 대체로 Barkhausen noise envelope은 두개의 peak 현상을 보였으며, 그 현상은 $180^{\circ}$ 자구벽(domain wall)이 생성과 소멸과정을 거듭할 때 많은 activation energy가 필요함에 따른 것으로 설명할 수 있었다. 선긋기 횟수를 늘려감에 따라 즉 선긋기의 간격이 줄어듦에 따라 Barkhausen noise envelope의 크기값이 감소하였지만, 선간격 9.75 mm부터는 감소현상이 둔화되는 것으로 나타났다. 이는 선긋기 획수가 늘어남에 따라 선긋기 근처에서 $180^{\circ}$ 자구의 생성과 소멸이 쉽게 일어나기 때문에 Barkhausen Noise의 크기가 감소하는 것으로 설명할 수 있다. 이러한 현상은 0.30 mm의 시편에서도 유사하게 설명될 수 있었다. Barkhausen noise power는 선긋기 간격이 줄어듦에 따라 감소하였으며, 각도변화에 따른 결과는 $50^{\circ}$ 근처에서 가장 적은 값을 보였다.

• 전자공학회논문지
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• 제50권1호
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• pp.15-20
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• 2013

일반적으로 에너지 검파 기반 스펙트럼 감지 방식은 잡음 전력에 대한 불확실성에 취약한 것으로 알려져 있다. 이러한 문제점을 해결하기 방안 중의 하나로 이중 임계값을 사용하는 에너지 검파 기반 협력 스펙트럼 감지 방식이 제안된 바 있다. 그러나 아직까지 페이딩 채널 환경에서 이 방식에 대한 성능 분석이 수행된 바 없다. 본 논문에서는 에너지 검파 기반 스펙트럼감지 방식에 대한 이전 연구 결과를 활용하여 에너지 검파 기반 협력 스펙트럼 감지 방식에 대한 닫힌 형태의 수학적 분석 결과를 제시하고자 한다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제6권4호
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• pp.894-903
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• 2014

Insertion loss prediction of large acoustical enclosures using Statistical Energy Analysis (SEA) method is presented. The SEA model consists of three elements: sound field inside the enclosure, vibration energy of the enclosure panel, and sound field outside the enclosure. It is assumed that the space surrounding the enclosure is sufficiently large so that there is no energy flow from the outside to the wall panel or to air cavity inside the enclosure. The comparison of the predicted insertion loss to the measured data for typical large acoustical enclosures shows good agreements. It is found that if the critical frequency of the wall panel falls above the frequency region of interest, insertion loss is dominated by the sound transmission loss of the wall panel and averaged sound absorption coefficient inside the enclosure. However, if the critical frequency of the wall panel falls into the frequency region of interest, acoustic power from the sound radiation by the wall panel must be added to the acoustic power from transmission through the panel.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문집
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• pp.869-874
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• 2002

Hermetic rotary compressor is one of the most important components for air conditioning system since it has a great effect on both the performance and the noise and vibration of the system. Noise and vibration of rotary compressor is occurred due to gas pulsation during compression process and unbalanced dynamic force. In order to reduce noise and vibration, It is necessary to identify sources of noise and vibration and effectively control them. Many approaches have been tried to identify noise sources of compressor. However, compressor noise source identification has proven to be difficult since the characteristics of compressor noise are complicated due to the interaction of the compressor parts and gas pulsation. In this work, Statistical Energy Analysis has been used to trace the energy flow in the compressor and identify transmission paths from the noise source to the sound field.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2007년도 공동학술대회 논문집
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• pp.297-302
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• 2007

Recently, electrical resistivity survey is used in the various fields and applied to urban area with many electrical noises. Therefor it's necessary to observe the electrical noise effect of the geological structure. The physical scale modeling was conducted for measuring the electric noise effect of the two geological models at various distances, depths and diameters of the electric noise objects. The results are as following. 1. When conductive noise object was vertical to the strike of geological structure and moved to the strike direction, the effect of conductive noise object at various separated distances to the measurement line was disappeared at a half distance measurement line length regardless of electrode arrays. 2. When conductive noise object was vertical to the strike of geological structure and moved to the strike direction, the effect of conductive noise object at various depths was disappeared at 4unit apart from the measurement line regardless of electrode arrays. 3. When conductive noise object was vertical to the strike of geological structure and moved to the strike direction, the effect of conductive noise object at various diameters was disappeared at 4unit apart from the measurement line regardless of electrode arrays.

• 한국소음진동공학회논문집
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• 제26권6_spc호
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• pp.674-679
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• 2016

According to the conventional studies on the noise and cardiovascular effect, railway noise is better associated with hypertension and adverse cardiovascular events than road traffic noise. But the underlying mechanisms remain unclear. We investigated the hypothesis that exposure to acute railway noise would the unfavorable effect of cardiovascular and autonomic system in healthy young subjects. Using a randomized, sham-controlled cross-over design, ten subjects were assigned to receive either an exposure to high speed train noise (84 dB) for 30 minutes or a control condition (non noise), separated by two days. Blood pressure, heart rate, augmentation index and heart rate variability as indices of cardiovascular and autonomic system function were measured at baseline, during, and recovery from two trials. The results show that exposure to acute railway noise significantly increased diastolic blood pressure and augmentation index, which may cause of adverse cardiovascular effects.

• 대한의용생체공학회:의공학회지
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• 제22권3호
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• pp.241-247
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• 2001

ABR(auditory brainstem response) is one of the audiometry which measures objective hearing threshold level by acquiring electric evoked potentials emanated from auditory nerve system responding to an auditory stimulation. However, the obtained potentials which are largely interfered by power line noise, have extremely low SNR, thus ensemble average algorithm is generally used. The purpose of this study was to investigate the effect of iteration number in ensemble average on the reduction of the power line noise. The power line noise was modeled to be a 60 Hz sinusoidal signal and the energy of the modeled signal was calculated when it was averaged. It was verified by simulation that the energy had the periodic zero points for each stimulation rate, and 60 Hz signal induced by the power line was applied to the developed ABR system to confirm that the period of zero energy point was the same with that of the simulation. By the properly selected iteration number, power line noise could be reduced and more reliable ABR could be acquired.

• 소음진동
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• 제7권6호
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• pp.919-929
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• 1997

Induction motors are used in many areas to transform electrical energy to mechanical energy. In the design of an induction motor, not only energy efficiency but also noise becomes an important factor. To effectively address the noise problem, it will be convenient if one can see where and how noise is generated and propagated. In this study sound radiation by an induction motor is visualized using cylindrical acoustic holography. To minimize the bias error by window effect Minimum Error Window(MEW) is used. Its performance is verified by numerical simulations. Based on these theoretical understanding, sound pressure measurement with an induction motor are performed. Not only sound radiation are visualized but sound pressure level and sound power level are also estimated. Results show that the main source is located at nearly bottom part of the motor and the total sound pressure level is 49dB, which satisfies the guideline value suggested by the KS C 4202.

• 한국통신학회논문지
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• 제42권5호
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• pp.982-984
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• 2017

시간 영역에서 펄스 레이다 신호는 송신 펄스가 존재하는 구간과 표적으로부터 반사된 수신 신호가 존재하는 구간으로 구분할 수 있으며, 수신 신호 성분은 송신 펄스에 비해 크기가 매우 작고, 표적으로 부터 반사된 성분을 제외하고는 잡음으로 구성되어 있다. 본 논문에서는 이러한 성질을 이용하여 잡음 전력에 대한 불확실성이 존재하는 환경에서 에너지 검파를 이용하여 레이다 신호를 검출하는 방안을 제시하고자 한다.