• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.1479-1486
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• 2000

This paper introduces the improved moving frame acoustic holography (MFAH) method and its application. MFAH allows us to visualize the noise generated by moving noise sources by employing a vertical line array of microphones affixed to the ground. The sound field generated by moving sources is different from that of stationary ones due to the movement of the sources. Therefore the measured sound pressure by the microphone on the ground has to be processed so that it cooperates the effect of the movement. This paper discusses the effect of moving noise sources on the obtained hologram by MFAH. This assures the applicability of MFAH to the visualization of moving sources. This paper also reviews the improved MFAH that can visualize a coherent narrow band noise and a pass-by noise. The practical applicability of the improved MFAH was demonstrated by visualizing tire noise during a pass-by test.

• 한국음향학회:학술대회논문집
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• 한국음향학회 2000년도 하계학술발표대회 논문집 제19권 1호
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• pp.291-294
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• 2000

가속 주행하는 차량의 소음을 줄이기 위해서는 각 소음원의 기여도를 파악하는 것이 필요하다. 본 논문에서는, 가속 주행하는 차량의 배기 토출 소음을 ISO362에서 규정한 음압 측정 지점에서 예측하기 위하여, 시간 영역에서 근접장 배기 토출 소음을 예측할 수 있는 시뮬레이션 프로그램 'WAVE'와 움직이는 음원의 방사 모델을 이용하였다. 가속 주행중 차량의 소음원에 의한 음파의 전달은 도플러효과와 시간 지연이 발생하며, 이를 고려하여 정지된 지점에서의 소음레벨을 예측하였으며, 배기 토출 소음의 예측을 통하여 가속주행소음에 대한 기여도와 그 소음 특성을 파악할 수 있다.

• 한국음향학회지
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• 제23권4호
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• pp.309-315
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• 2004

본 연구에서는 가속주행소음 (pass-by noise) 시험을 측정할 때 차량 각 부분에서 발생하는 소음 기여율을 산정하고자, 그 선행연구로 정지 차량의 좌우 측면에서 음향 인텐시티 방법을 이용하여 근접 방사소음 특성을 연구하였다. 가속주행소음 측정구간의 엔진 회전수 대역인 2,800 rpm과 3,200 rpm으로 구분하여 시험차량 중심축 선을 기준으로 7.5m 떨어진 지점에서 음압을 측정하여 주파수별 지향특성을 해석하였다. 이 결과는 차량 소음 저감에 응용할 수 있다.

• 대한금속재료학회지
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• 제46권9호
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• pp.545-553
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• 2008

Dynamic deformation behavior of ultra-fine-grained pure coppers fabricated by equal channel angular pressing (ECAP) was investigated in this study. Dynamic torsional tests were conducted on four copper specimens using a torsional Kolsky bar, and then the test data were analyzed by their microstructures and tensile properties. The 1-pass ECAP'ed specimen consisted of fine dislocation cell structures elongated along the ECAP direction, which were changed to very fine, equiaxed subgrains of 300~400 nm in size as the pass number increased. The dynamic torsional test results indicated that maximum shear stress increased with increasing ECAP pass number. Adiabatic shear bands were not found at the gage center of the dynamically deformed torsional specimen of the 1- or 4-pass ECAP'ed specimen, while some weak bands were observed in the 8-pass ECAP'ed specimen. These findings suggested that the grain refinement according to the ECAP was very effective in strengthening of pure coppers, and that ECAP'ed coppers could be used without serious reduction in fracture resistance under dynamic torsional loading as adiabatic shear bands were hardly formed.

• 한국ITS학회 논문지
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• 제9권4호
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• pp.90-101
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• 2010

하이패스플러스카드, 지불SAM, 지불단말기, 정산시스템, OBU 등으로 이루어진 기존 하이패스플러스카드 시스템은 표준에 정의되지 않은 세부사항들로 인하여, 지역 간 사업자 간 교통수단 간 호환이 불가능하다. 이로 인해 많은 비효율적인 문제가 있음을 발견하였다. 예컨대 기존 하이패스플러스카드 사용자가 다른 사업자가 운영하는 대중교통 수단을 이용하려고 하면, 각각 그에 맞는 카드를 따로 구입하여 여러 개의 카드를 소지하고 다녀야 하는 번거로움이 있다. 또한 하이패스플러스카드 사업자가 이미 구축된 타 인프라에 기존 하이패스플러스카드 시스템을 적용하려고 하면, 그 인프라를 활용하지 못하고, 하이패스플러스카드만의 기술이 적용된 인프라를 구축해야 하는 중복투자가 발생한다. 이를 해결하고자 기존 하이패스플러스카드 시스템을 분석하여 문제점을 찾고, 기존 하이패스플러스카드 시스템을 수정하여, 하나의 카드로 전국 어디에서나 이용 가능한 전국호환 교통카드 하이패스플러스카드 시스템을 개발하였다. 그리고 이 전국호환 하이패스플러스카드 시스템에 대한 기술 및 성능을 보장하기 위해 적합성 평가를 하여 통과하였다. 또한 하이플러스카드, 금융결제원, 코레일네트웍스가 공동으로 광주광역시에서 6개월간 테스트베드를 운영함으로써, 실제 환경에 적용했을 때 나타날 수 있는 문제점을 발견하고 이를 보완하여 성공적인 결과를 거두었다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 추계학술대회논문집
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• pp.291-295
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• 2003

The occurrence of ductile fracture is the working limit of many metal forming processes. It is necessary to predict the criteria and to apply the condition in a process design. Over the years. the way for clarifying conditions have been studied and presented. However such a way needs lots of experiments and analysis. In this study, in order to determine the critical damage value of a used material Cu 4N, it was performed a tensile test and FEM analysis by using DEFORM 2D. For applying the obtained critical damage value it was also performed a upsetting test by using DEFORM 2D. The way of determining a critical damage value which is presented in this study will make possible to find easily it which is one of the working limit factor. And the way of determining a critical damage value will make possible to find in multi-pass drawing process.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 추계학술대회 논문집
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• pp.225-228
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• 2009

The simulated indoor pass-by noise measurement system is the tool to measure and evaluate the pass-by noise at the test laboratory, without doing measurement at the field. This measurement system can realize the precision measurement under the specific condition and overcome the limitations of the field measurement, i.e. weather conditions, repeatability, .. This measurement system is done in time domain process using the array techniques, which synchronizes the time signals. The reliability of the obtained result depends on the array shapes, which can generate the moving source effect. In this paper, the validations are checked focusing the time domain synchronization of the signals with the optimum microphone array shape.

• The Journal of Korean Physical Therapy
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• 제21권1호
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• pp.9-17
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• 2009

Purpose: The purpose of this study was to determine reliability and validity of the Postural Assessment Scale for Stroke Patients (PASS) in chronic stroke patients. Methods: A total of 43 stroke patients, who had a stroke more than 6 months previously, participated in the study. Reliability was determined by the intra-class correlation coefficient (ICC$_{3,1}$), Bland and Altman method and Cronbach's alpha by internal consistency. Validity was examined by correlation the PASS scores to the Berg Balance Scale (BBS), Trunk Control Test (TCT), and Fugl-Meyer Balance (FM-B) score. Results: The intra-rater reliability and the Absolute reliability of the PASS was good ICC$_{3,1}$=0.97 (95%CI 0.95$\sim$0.99) and excellent SEM=1.01 respectively. Cronbach's alpha value for PASS was found to be 0.94. There were significant correlations between the PASS and BBS, TCT, FM-B (r=0.65－0.96, p<0.01). Conclusion: The PASS provide reliable and valid instrument of the postural control assessment for chronic stroke patients.

• 한국소음진동공학회논문집
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• 제16권11호
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• pp.1124-1131
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• 2006

This paper presents a novel method to determine sound power level(PWL) emitted by a travelling vehicle for road traffic noise simulation. The PWL is evaluated by the equivalent sound pressure level (SPL) measured by close proximity method and the sound power correction factor derived from the maximum SPL measured by pass-by method and the propagation attenuation of vehicle noise during the pass-by measurement. Using the method, we derive the empirical formula for PWL estimation in 1/1-octave and overall frequency bands for 8 vehicles (automobile, SUV, small truck, large bus, trailer, 3 dump trucks) tested at two road surfaces (dense graded asphalt, 30mm transverse tinning concrete) of Korean highway test road. The suggested approach, if securing sufficient data to represent the acoustic characteristics of all vehicle types, has il strong merit to be able to evaluate sound power levels for any combination of vehicle categories and traffic volumes.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.421-427
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• 2006

This paper presents a novel method to determine sound power level(PWL) emitted by a travelling vehicle for road traffic noise simulation. The PWL is evaluated by the equivalent sound pressure level(SPL) measured by close proximity method and the sound power correction factor derived from the maximum SPL measured by pass-by method and the propagation attenuation of vehicle noise during the pass-by measurement. Using the method, we derive the empirical formula for PWL estimation in 1/1-octave and overall frequency bands for 8 vehicles(automobile, SUV, small truck, large bus, trailer, 3 dump trucks) tested at two road surfaces(dense graded asphalt, 30mm transverse tinning concrete) of Korean highway test road. The suggested approach, if securing sufficient data to represent the acoustic characteristics of au vehicle types, has a strong merit to be able to evaluate sound power levels for any combination of vehicle categories and traffic volumes.