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황요하 한국소음진동공학회 1992 소음 진동 Vol.2 No.4
Active vibration control is presented with simulation and experiment. Dynamic Data System(DDS) method is used for system modeling and this model is combined with an forecasting control technique to derive a control equation. In the experiment, on-line digital computer monitors structural vibration and calculates control input. The control input is sent to an electromagnetic actuator which cancels the structural vibration. Experiment is performed first with a simple beam setup to demonstrate the effetiveness of this method. This method is then applied to a color laser printer to actively modify the structure. The beam experiment showed vibration reduction of over 60% with one-and two-DOF models. In the printer structure experiment, the first mode of 308 Hz was successfully controlled with a one-DOF model.
전달경로의 차이를 이용한 새로운 차량용 능동 머플러의 개발
황요하(Hwang, Yo-Ha),이종민(Lee, Jong-Min),김승종(Kim, Seung-Jong) 한국소음진동공학회 2002 한국소음진동공학회 논문집 Vol.12 No.5
A new active muffler system has been developed and its superior performance on both noise reduction and engine torque increase is demonstrated with experiment. Main characteristic of the proposed muffler system is the use of destructive interference by transmission path difference of divided exhaust pipes to reduce major exhaust noise components thereby overcoming problems of other active exhaust noise control methods. The exhaust pipe is divided into two sections and joined again downstream. One divided pipe has a sliding mechanism to vary its length, which is controlled to make half wavelength transmission path difference for the major engine rpm frequency. In this system one divided pipe is used to control major rpm frequency and its Harmonics and another pipe is used to control noise component double the frequency of rpm. An after-market tuning muffler, which has very simple internal structure and minimal back pressure, is also installed to remove remaining wideband noise. To make the system to be small enough to be practical, conventional muffler is also installed and used in low rpm range and active muffler is only employed in high rpm range. Noise reduction of the proposed system is comparable to conventional passive muffler. The engine dynamo test has proved the proposed system can recover almost all the torque lost by conventional muffler.
승용차용 능동제어식 현가시스템의 개발(2); 실차 성능실험 및 결과
황요하(Y.Hwang),홍예선(Y.S.Hong),이종민(J.Lee),배준영(J.Y.Bae) 한국자동차공학회 1993 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Test results on prototype car equipped with active suspension system is reported. Control theory is explained first. Simulation for feasibility and parameter tuning, control module test using hydraulic exciter and test run. and performance evaluation of the test car are reported successively. Emphasis was put on modification of control theory which caused many unexpected problems in actual implementation.<br/>
유한요소법을 이용한 제진강판의 동특성 해석 및 이의 실험적 검증
황요하(Y. H. Hwang),이종민(J. M. Lee),이성한(S. H. Lee),임장근(J. K. Lim) 한국자동차공학회 1996 한국 자동차공학회논문집 Vol.4 No.5
Dynamic characteristics of the vibration-damping steel sheet(VDSS) have been studied through analytical methods and experiments for years, but because of the complexity of the structure, the analytical analysis was confined to simple structures. FE analysis has been widely used in this area to overcome the conventional method's limitations. In this thesis, the effective and accurate FE analysis method is suggested on the analysis of dynamic characteristics of VDSS. First, a simple structure was analyzed by FEM and its analysis results were compared with experimental modal analysis results to decide the proper analysis conditions. In next step, using the analysis condition obtained in the first step, the complex VDSS structure was analyzed and the results were compared with experimental results to verify the correctness of the FE analysis conditions.<br/>
승용차용 능동제어식 현가시스템의 개발(2); 실차 성능실험 및 결과
황요하(Y. H. Hwang),홍예선(Y. S. Hong),이종민(J. M. Lee),배준영(J. Y. Bae) 한국자동차공학회 1994 한국 자동차공학회논문집 Vol.2 No.2
Performance test result on prototype car equipped with low-band type active suspension system is repor- ted. Control theory is explained first. Simulation for feasibility and parameter tuning, control module test using hydraulic exciter and test run, and performance evaluation of the test car on test track are reported successively. Emphasis was put on modification of control theory which caused many unexpected problems in actual implementation.<br/>
터보회전기기의 진동모니터링 및 진단을 위한 이산 은닉 마르코프 모델에 관한 연구
이종민,황요하,송창섭 한국유체기계학회 2004 한국유체기계학회 논문집 Vol.7 No.2
Condition monitoring is very important in turbo machinery because single failure could cause critical damages to its plant. So, automatic fault recognition has been one of the main research topics in condition monitoring area. We have used a relatively new fault recognition method, Hidden Markov Model(HMM), for mechanical system. It has been widely used in speech recognition, however, its application to fault recognition of mechanical signal has been very limited despite its good potential. In this paper, discrete HMM(DHMM) was used to recognize the faults of rotor system to study its fault recognition ability. We set up a rotor kit under unbalance and oil whirl conditions and sampled vibration signals of two failure conditions. DHMMs of each failure condition were trained using sampled signals. Next, we changed the setup and the rotating speed of the rotor kit. We sampled vibration signals and each DHMM was applied to these sampled data. It was found that DHMMs trained by data of one rotating speed have shown good fault recognition ability in spite of lack of training data, but DHMMs trained by data of four different rotating speeds have shown better robustness.