• 대한기계학회논문집
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• 제16권1호
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• pp.13-21
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• 1992

본 연구에서는 구조-음향모드 연성계수를 이용하여 심각한 소음문제가 발생하 는 경우의 효과적인 소음저감 방안을 제시하고, 제작된 차실모델에 대한 소음저감 시 뮬레이션을 수행한 후 그 결과를 실험치와 비교함으로써 수립된 소음저감 방안의 신뢰 도와 유용성을 확인하였다.

• 음성과학
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• 제10권2호
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• pp.99-109
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• 2003

The purpose of this study was to analyze and compare head register with chest register of singers acoustically. Fifteen healthy tenor major students were participated. Fifteen healthy untrained adults were chosen as the control group for this study. Long term average (LTA) power spectrum using the Fast Fourier transform (FFT) algorithm and Linear predictive coding (LPC) filter response were made with /a/ sustained in both head (G4, 392 Hz) and chest registers (C3, 131 Hz). Statistical analysis was performed using the Mann-Whitney test. In the LTA power spectrum, head register of singers increased in the level of energy gain within the frequency of 2.2-3.4 kHz (p<0.01), and 7.5-8.4 kHz (p<0.01, p<0.05). Chest register of singers increased in the frequency of 2.2-3.1 kHz (p<0.01), 7.8-8.4 kHz (p<0.05) and around 9.6 kHz (p<0.01). The LTA power spectrum revealed a peak of acoustic energy around 2,500 Hz, known as the singer's formant and another peak of acoustic energy around 8,000 Hz in the singer's voice.

• 대한후두음성언어의학회지
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• 제20권1호
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• pp.52-56
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• 2009

Background and Objectives : Vocal nodule is common inflammatory vocal cord lesion which could be improved by voice rest or voice therapy. But some patients, who do not have any improvement after voice therapy, should take laryngomicorsurgery or additional long-term voice therapy. So we try to find prognostic factors which affect the results of voice therapy. Materials and Methods: There are 36 patients (response group) whose symptoms improved after initial voice therapy and 16 patients (no response group) whose symptoms did not improve at all. We compared clinical features (durations of symptoms, voice abuse, laryngopharyngeal reflux), GRBAS scale, acoustic analysis, aerodynamic analysis and voice handicap index between the two groups from January, 2006 to June, 2008. Results: Response group underwent voice therapy 4.5 times (ave.) and no response group underwent 6.7 times (ave.). No response group has longer duration of symptoms, higher GRBAS scale score, higher NIH ratio, and higher MFR than those of response group. Conclusion : This study found that the prognosis of voice therapy in patients who have longer duration of symptoms, high NIH ratio, and bad perceptional test result is not likely to be good. In those cases, we should recommend earlier surgery, voice therapy after surgery, and inform about the necessity of long-term voice rehabilitation or voice therapy in order to get favorable compliance.

• 생약학회지
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• 제44권2호
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• pp.97-103
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• 2013

Schizophrenia is a severe psychiatric disorder and characterized by positive symptom (i.e., delusions, hallucinations), negative symptom (i.e., lack of emotion, social withdrawal), and cognitive impairment. Previously, we reported that the ethanolic extract of Prunella vulgaris var. lilacina attenuated the MK-801-induced schizophrenia-like behaviors such as prepulse inhibition (PPI) deficits and cognitive impairment in mice. The aim of the present study was to investigate whether danshensu isolated from P. vulgaris var. lilacina attenuates MK-801-induced sensorimotor gating dysfunction (PPI deficits), hyperlocomotion, and memory impairment in mice. Acute administration of danshensu (1, 3, or 10 mg/kg) significantly ameliorated the MK-801-induced PPI deficits in the acoustic startle response test. We also observed that the impaired recognition memory induced by MK-801 was attenuated by danshensu (1 mg/kg) in the novel object recognition test. However, danshensu failed to reverse the MK-801-induced hyperlocomotion in the open-field test. Collectively, the present results indicate danshensu would be an active agent for treating neuropsychiatric disorders such as schizophrenia.

• 한국소음진동공학회논문집
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• 제22권6호
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• pp.550-555
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• 2012

Among the various elements affecting a customer's evaluation of automobile quality, buzz, squeak and rattle(BSR) have been considered to be major factors. In most vehicle manufacturers, the BSR problems are solved by find-fix method with the vehicle road test, mainly due to various excitation sources, complex generation mechanism and subjective response. To systematically tackle the BSR problems in early stage of the vehicle development cycle, these difficulties should be resolved. The aim of the present paper is to characterize the sound quality property of BSR noise that can be used to assess the subjective responses to BSR. The four sound metrics from Zwicker's sound quality parameter are computed for the signals recorded for eight BSR noise source regions localized by using the acoustic-field visualized results. Then, the jury test of BSR noise are performed. On the basis of the computed sound metrics and jury test result is evaluated to represent the harshness of BSR noise. It is expected that the developed BSR measuring system and sound quality properties can be used to reduce the automotive interior BSR noise in terms of subjective levels as well as objective levels.

• Composites Research
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• 제14권1호
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• pp.1-7
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• 2001

본 연구에서는 유리 섬유 강화 열가소성 복합재료의 손상평가를 음향방출법을 이용하여 관찰하였다. 시편은 PET와 유리섬유를 7겹으로 적층시켜 만들었으며 두께는 1.7mm이다. 노치 시험편과 풍격 시험편을 제작하여 단순인장 시험과 부하-제하 시험을 수행하였다. AE 신호의 파라미터와 파괴모드간의 관계를 찾아내기 위해 충격 에너지와 노치비의 함수로 AE신호를 측정하였다. 실험견과 모재의 미소균열과 성장 때문에 저진폭 AE 신호가 나타났고, 중진폭 신호는 섬유와 모재간의 층간분리와 계면분리에 대응됐다. 또한 90dB의 고진폭 영역에서는 유리섬유의 파단과 대응되었다 층간분리와 모재의 균열과 음력집중의 영향 때문에 노치비와 충격 에너지가 증가할수록 인장강도는 감소했다. 손상영역의 비율에 따라 AE 신호는 넓은 영역의 주파수가 나타날 뿐만 아니라 신호도 증가하였다.

• 한국소음진동공학회논문집
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• 제24권3호
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• pp.171-179
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• 2014

썬루프 버페팅 현상은 차량 주행시 발생하는 주요 바람소리 문제점 중 하나이다. 버페팅 문제점을 해결하기 위해서 전산 해석을 적용한다면, 실험적 방법보다 비용을 절감할 뿐 아니라 발생 원리 또한 규명할 수 있다. 그러나 전산 해석을 이용하기 위해서는 해석 결과의 정확성이 보장되어야 실제 차량 개발에 적용할 수 있다. 이 연구에서는 해석적 방법의 정확도 향상을 위해 주요 상업용 전산해석 소프트웨어들의 썬루프 버페팅 현상 예측에 대한 벤치마크 테스트를 수행하였다. 해석 대상은 차량의 형상을 간략하게 만든 HSM(Hyundai simplified model)을 이용하였고, 정확도 비교를 위해 속도별 버페팅 현상에 대한 실험을 현대자동차 공력무향풍동에서 실차내부의 흡음재에 의한 효과를 해석적으로 고려하기 위해 음향 응답 실험을 수행하여 해석 결과 정확도 향상을 위해 각 상용 소프트웨어 제작사에 해석 전에 제공 하였다. 이 연구를 통해 대부분의 상용 소프트웨어들이 실험결과와 유사한 해석 결과를 도출하였다. 또한, 실제 차량 개발에서 적용하기 위한 해석 예측 우선순위를 서로 공유하여 추가 해석을 통해 차량 개발에 적용 가능한 보다 정밀한 해석 정확도를 얻어낼 수 있었다.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2001년도 춘계학술발표대회 논문집
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• pp.254-257
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• 2001

An intensity-based optical fiber vibration sensor is applied to detect and evaluate damages and fiber failure of composites. The optical fiber vibration sensor is constructed by placing two cleaved fiber end, one of which is cantilevered in a hollow glass tube. The movement of the cantilevered section lags behind the rest of the sensor in response to an applied vibration and the amount of light coupled between the two fibers is thereby modulated. Vibration characteristics of the optical fiber vibration sensor are investigated. Surface mounted optical fiber vibration sensor is used in tensile and indentation test. Experimental results show that the optical fiber sensor can detect damages and fiber failure of composites correctly.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집A
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• pp.547-552
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• 2001

An intensity-based optical fiber vibration sensor is applied to detect and evaluate damages and fiber failure of composites. The optical fiber vibration sensor is constructed by placing two cleaved fiber end, one of which is cantilevered in a hollow glass tube. The movement of the cantilevered section lags behind the rest of the sensor in response to an applied vibration and the amount of light coupled between the two fibers is thereby modulated. Vibration characteristics of the optical fiber vibration sensor are investigated. Surface mounted optical fiber vibration sensor is used in tensile and indentation test. Experimental results show that the optical fiber sensor can detect damages and fiber failure of composites correctly.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.72-74
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• 2014

Multilayer ceramic capacitor (MLCC) makes acoustic noise of electronic devices. Conversed piezoelectric effect of dielectric substance consists of $BaTiO_3$ causes vibration of MLCC so it must be analyzed to reduce the noise. Thus, finite element model for piezoelectric analysis of MLCC was constructed in this paper. Piezoelectric characteristics of MLCC was considered for the accurate simulation result. Displacement response for sinusoidal voltage signal was measured and simulation result was verified with test result.