• 한국공작기계학회논문집
• /
• 제12권6호
• /
• pp.50-55
• /
• 2003

This study proposed the analysis of damage detection due to the change of the stiffness of structure by using the original and modified dynamic characteristics. The present approach allows the use of composite data which consist of eigenvalues and eigenvectors. The suggested method is applied to examples of a cantilever and 3 degree of freedom system by modifying the stiffness. The predicted damage detections are in good agreement with these from the structural reanalysis using the modified stiffness.

• Journal of Power Electronics
• /
• 제9권3호
• /
• pp.507-515
• /
• 2009

This paper proposes an autonomous decentralized control for a parallel connected uninterruptible power supply (UPS) system based on a fast power detection method using a FPGA based hardware controller for a single phase system. Each UPS unit detects only its output voltage and current without communications signal exchange and a quasi dq transformation method is applied to detect the phase and amplitude of the output voltage and the output current for the single phase system. Fast power detection can be achieved based on a quasi dq transformation, which results in a realization of very fast transient response under rapid load change. In the proposed method, the entire control system is implemented in one FPGA chip. Complicated calculations are assigned to hardware calculation logic, and the parallel processing circuit makes it possible to realize minimized calculation time. Also, an Nios II CPU core is implemented in the same FPGA chip, and the software can be applied for non-time critical calculations. Applying this control system, an autonomous decentralized UPS system with very fast transient response is realized. Feasibility and stable operation are confirmed by means of an experimental setup with three UPSs connected in parallel. Also, rapid load change is applied and excellent performance of the system is confirmed in terms of transient response and stability.

• 한국자동차공학회논문집
• /
• 제8권1호
• /
• pp.23-31
• /
• 2000

Knock and misfire, kinds of abnormal combustion, are highly undesirable effect on the internal combustion engine. So, it is important to detect these avnormal combuition and control the ignition timing etc. to avoid these mal-effect factors in real engine system. In this study, the system which detects the knock and the misfire using by spark plug is presented. This system is based on the effect of modulation breakdown voltage(BDV) between the spark gaps. The voltage drop between spark plug electrodes, when an electrical breakdown is initiated, depends on the temperature and pressure in combustion chamber. So, we can detect knock and misfire that produce changes in gas temperature and pressure (consequently, its density) using by BDV signal change which carries information about the character of combustion.

• 전기학회논문지
• /
• 제63권3호
• /
• pp.376-382
• /
• 2014

E-Actuator is an essential part of an eVGT, it receives the command from the main ECU and controls the vane. An e-Actuator failure can cause an abrupt change in engine output and it may induce an accident. Therefore, it is required to detect anomalies in the e-Actuator in real time to prevent accidents. In this paper, an e-Actuator fault detection method using on-line parameter identification is proposed. To implement on-line fault detection algorithm, many constraints are considered. The test input and sampling rate are selected considering the constraints. And new recursive system identification algorithm is proposed which reduces the memory and MCU power dramatically. The relationship between the identified parameters and real elements such as gears, spring and motor are derived. The fault detection method using the relationship is proposed. The experiments with the real broken gears show the effectiveness of the proposed algorithm. It is expected that the real time fault detection is possible and it can improve the safety of eVGT system.

• 대한기계학회논문집A
• /
• 제26권5호
• /
• pp.864-871
• /
• 2002

Acoustic emission(AE) technique has been applied to not only mechanical property testing but also on-line monitoring of the entire structure or a limit zone only. Although several AE devices have already been developed for on-line monitoring, the price of these systems is very high and it is difficult for the field to apply yet. In this study, we developed a specially designed PC-based leak detection system using A/D board. In this paper, AE technique has been applied to detect leak for heat exchanger by analyzing the characteristics of signal obtained from leak. It was confirmed that the characteristics of the signal generated by the turbulence of gas in the heat exchanger is narrow band signal having between 130-250kHz. Generally, the amplitude of leak signal is increased as the leak size increasing, but showed no significant change at frequency characteristic. Leak source location can be found by determining for the paint of highest signal amplitude by comparing with several fixed sensors. In this paper, AE results are compared with the PC-based leak detection system using A/D board.

• 대한전기학회논문지:전력기술부문A
• /
• 제48권10호
• /
• pp.1259-1263
• /
• 1999

In this paper, a method to guarantee system continuity is developed, which can be applied to discontinuity problem in the time domain of restructurable control system. This method can be summarized as input alternation using weight change considering convergence speed of system mode. Input is changed from 'system continuity guarantee input,' which is defined as a input that minimizes the change of state variables, to 'alternative controller input,' which is selected by Neil's PI/EAM[3]. AIDC aircraft model is used for simulation. By showing the waveform of system input and state variable, we can sure that this method is effective for depression of system shock like jerk.

• 한국컴퓨터정보학회논문지
• /
• 제13권5호
• /
• pp.19-26
• /
• 2008

본 논문에서는 실시간 얼굴검출을 위하여 감시카메라에서 입력된 RGB영상을 YCbCr 영상으로 변환한 후 연속된 두 영상의 차를 구하고 Glassfire 라벨링을 실시했다. 라벨링 결과 가장 넓은 구역의 면적과 Area 임계치 값을 비교하여 임계값 이상의 면적이면 동작변환으로 인식하고 영상을 추출하였다. 이렇게 추출된 동작변환 영상을 대상으로 얼굴 검출을 실시하였다. 얼굴 검출에 필요한 특징을 추출하기 위해 AdaBoost알고리즘을 사용하였다.

• 제어로봇시스템학회논문지
• /
• 제21권2호
• /
• pp.102-107
• /
• 2015

In this paper, we propose a technique of drowsiness detection using a histogram for vehicle safety. The drowsiness of vehicle drivers is often the main cause of many vehicle accidents. Therefore, the checking of eye images in order to detect the drowsiness status of a driver is very important for preventing accidents. In our suggested method, we analyse the changes of a histogram of eye region images which are acquired using a CCD camera. We develop a drowsiness detection system using this histogram change information. The experimental results show that the proposed method enhances the accuracy of detecting drowsiness to nearly 97%, and can be used to prevent accidents due to driver drowsiness.

• 대한임베디드공학회논문지
• /
• 제10권2호
• /
• pp.101-108
• /
• 2015

In this paper, a robust traffic light detection method is proposed by using vision sensor and DGPS(Difference Global Positioning System). The conventional vision-based detection methods are very sensitive to illumination change, for instance, low visibility at night time or highly reflection by bright light. To solve these limitations in visual sensor, DGPS is incorporated to determine the location and shape of traffic lights which are available from traffic light database. Furthermore the geometric relationship between traffic light and vision sensor is used to locate the traffic light in the image by using DGPS information. The empirical results show that the proposed method improves by 51% in detection rate for night time with marginal improvement in daytime environment.

• 대한의용생체공학회:학술대회논문집
• /
• 대한의용생체공학회 1997년도 추계학술대회
• /
• pp.428-431
• /
• 1997

This study is the basic research on esophageal balloon dialation with automatic detection of the pressure change in the balloon and analysis using personal computer. In conventional method, the esophageal stricture is cured by surgically. Recently, balloon dialation method has been proposed and is popularized. In balloon dialation, detecting esophageal rupture is very important. When using radiological investigation, the leak of contrast medium is very dangerous. In proposed method, the detection of esopageal rupture can be peformed by detecting and analyze the pressure change of dialation balloon. Experimental system is composed of balloon catheter, pressure pump, pressure sensor, A/D converter and PC.