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CPX 및 Pass-by 계측을 이용한 단독 주행 차량의 음향파워 평가 방법에 관한 연구
최태묵(Choi, T.M.),문성호(Moon, S.H.),서영국(Seo, Y.G.),김진형(Kim, J.H.),김병희(Kim, B.H.),배효준(Bae, H.J.),지우진(Ji, W.J.),조대승(Cho, D.S.) 한국소음진동공학회 2006 한국소음진동공학회 논문집 Vol.16 No.11
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.
웨이블렛 변환과 신경망 알고리즘을 이용한 회전기기 결함진단
최태묵(TAE-MUK CHOI),조대승(DAE-SEUNG CHO) 한국해양공학회 2002 韓國海洋工學會誌 Vol.16 No.5
The fault detection and diagnosis of rotating machinery widely used in plants including the ship are important for maintaining the performance of plants. Recently, the wavelet transform has been recognized an efficient method to detect a little variation of physical quantities by the synchronous localization of time and frequency domains using the translation and dilation of signals. In this paper, in order to develop efficient and reliable fault detection and diagnosis system of rotating machines, the performance of wavelet transformation to detect a little variation of machine status and neural network to diagnose the cause of machine faults are investigated and experimented.
포장노면 종류에 따른 타이어/노면 마찰 소음의 실험적 평가
김진형(Kim, J.H.),최태묵(Choi, T.M.),문성호(Moon, S.H.),서영국(Seo, Y.G.),박준석(Park, J.S.),도천수(Do, C.S.),조대승(Cho, D.S.) 한국소음진동공학회 2006 한국소음진동공학회 논문집 Vol.16 No.10
In this paper, we present noise measurement results of 8 vehicles. The measurement was done by a close proximity method attaching surface microphones on the test vehicle. For the 9 road surface types constructed at Korean highway test road, the vehicles were tested from 50 to 120 km/h at the interval of 10 km/h in normal steady state and inertia cruising conditions. Using the results, we evaluate and discuss the effect of vehicle noise generation depending on the different conditions for vehicle type, speed, road surface and loading condition, especially focused on friction noise between tyre and road surface.
김국현(Kookhyun Kim),김진형(Jin-Hyeong Kim),최태묵(Tae-Muk Choi),김윤환(Yun-Hwan Kim),조대승(Dae-Seung Cho) 한국해양공학회 2009 韓國海洋工學會誌 Vol.23 No.6
The radar cross section (RCS) of a warship is one of the most important design features in terms of her survivability in hostile environments. Ocean waves continuously changes the attitude of an objective warship to hostile radar and distorts the RCS as a result. This paper presents a dynamic RCS analysis technique and procedure that considers temporal ship motion. First, data sets are prepared for ship motions in 6 degrees of freedom, which are numerically simulated for an objective warship via frequency to time domain conversion with response amplitude operators and specified ocean wave spectra. Second, a series of RCS analysis models are transformed geometrically by referring to ship motion data sets. Finally, temporal RCS analyses are carried out with the RCS simulation code, SYSCOS. As an example, RCS analysis results are given for a virtual warship, which show that ship motions temporally change RCS values and cause RCS reduction compared with static value in terms of mean values.